JP2009197681A - Lash adjuster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lash adjuster which quickly moves an adjusting screw in a protruding direction and resists the wear of pressure side flanks of male and female screws even when assembled in an engine rotating at high speed and in an engine including a constituting member of a valve gear having a heavy inertial weight. <P>SOLUTION: The lash adjuster 1 comprises a nut member 13 inserted into a receiving hole 12 opened to the top surface of a cylinder head 2, an adjusting screw 16 including on an outer periphery a male screw 15 engaged with a female screw 14 formed on an inner periphery of the nut member 13 so as to be threaded, and a return spring 18 for biasing the adjusting screw 16 in an upwardly protruding direction from the nut member 13, and rockably supports an arm 7 of a valve gear by a projecting end 21 from the nut member 13 of the adjusting screw 16, wherein the return spring 18 is formed of a plurality of coil springs 23, 24 internally and externally superposed with each other. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lash adjuster incorporated in an engine valve gear.

  As a valve operating device that operates a valve provided at the intake port or exhaust port of an engine, the central part of the arm supported so as to be swingable with one end as a fulcrum is pushed down by a cam, and the valve stem is moved at the other end of the arm. One end of the arm that is pushed down (swing arm type valve operating device) or the arm supported so as to be able to swing with the center as a fulcrum is pushed up with a cam, and the valve stem is pushed down at the other end of the arm There are known ones (rocker arm type valve operating device), a lifter body supported so as to be slidable up and down by a cam, and a valve stem pushed down by the lifter body (direct type valve operating device).

  In these valve operating apparatuses, during engine operation, gaps between the constituent members of the valve operating apparatus change due to thermal expansion differences that occur between the constituent members of the valve operating apparatus, and abnormal noise and compression leakage occur due to changes in the gaps. There is a fear. Further, even if the sliding portion of the valve operating device is worn, the gap between the constituent members of the valve operating device changes, and there is a possibility that abnormal noise is generated due to the change in the clearance.

  In order to prevent this abnormal noise and compression leakage, generally, a lash adjuster is incorporated in the valve operating device, and the lash adjuster absorbs a change in a gap between components of the valve operating device.

  As such a lash adjuster, in the above swing arm type valve gear, the nut member inserted into the accommodation hole opened on the upper surface of the cylinder head and the female screw formed on the inner periphery of the nut member are screw-engaged. An adjusting screw having a male screw on the outer periphery, and a return spring that urges the adjusting screw in a direction protruding upward from the nut member. The protruding end of the adjusting screw from the nut member holds the arm of the valve gear. There is known one that can swingably (Patent Document 1).

  In the direct valve operating apparatus, a lifter body that is slidably inserted into a guide hole formed in the cylinder head, a nut member that moves up and down integrally with the lifter body, and an inner periphery of the nut member An adjustment screw having a male screw on its outer periphery that engages with the formed female screw, and a return spring that urges the adjustment screw in a direction that protrudes downward from the nut member, from the nut member of the adjustment screw A device that presses a valve stem of a valve operating device at a protruding end is known (Patent Document 2).

  Further, in the rocker arm type valve gear, the screw member is engaged with a nut member inserted into a receiving hole opened in the lower surface of the arm that swings according to the rotation of the cam, and a female screw formed on the inner periphery of the nut member. An adjusting screw having a male screw on the outer periphery thereof, and a return spring for biasing the adjusting screw in a direction protruding downward from the nut member, and a protruding end of the adjusting screw from the nut member What presses a valve stem is known (patent document 3).

  In these lash adjusters, the male screw of the adjusting screw and the female screw of the nut member are the pressure side flank that receives pressure when a load in the direction in which the adjusting screw is pushed into the nut member (hereinafter referred to as the “pushing direction”) is applied. The flank angle is formed in a sawtooth shape larger than the flank angle of the play side flank, and when a static load in the push-in direction is applied to the adjustment screw, it is adjusted by the frictional resistance between the pressure side flank of the male screw and the female screw. When the screw is prevented from rotating and, on the other hand, when a static load in the protruding direction is applied to the adjusting screw, the adjusting screw is allowed to rotate by sliding between the play side flank of the male screw and the female screw.

  Therefore, when a load in the pushing direction is applied to the adjustment screw due to the rotation of the cam, the pressure side flank of the male screw is received by the pressure side flank of the female screw, and the axial position of the adjustment screw is fixed. Strictly speaking, a slight slip occurs between the pressure flank of the male screw and the female screw at this time, and the adjustment screw moves in the pushing direction due to the sliding, but when the cam further rotates and the load in the pushing direction is released. In addition, the adjustment screw moves in the protruding direction due to the load in the protruding direction applied from the return spring, and returns to the original position.

  In addition, when the gap between the components of the valve operating device becomes large due to thermal expansion of the valve operating device, the cam is further pushed than the adjustment screw is pushed in when the load in the pushing direction is applied by the cam. The amount of protrusion of the adjusting screw when the load in the pushing direction is released by rotation is increased. As a result, each time the cam rotates, the adjustment screw gradually moves in the protruding direction to absorb the change in the gap between the constituent members of the valve gear.

On the other hand, when the gap between the components of the valve operating device becomes small, the cam rotates further than the amount of pushing of the adjusting screw when the load in the pushing direction is applied by the cam. The protruding amount of the adjusting screw when released is reduced. As a result, each time the cam rotates, the adjustment screw gradually moves in the push-in direction to absorb the change in the gap between the constituent members of the valve gear.
JP 2005-273510 A Japanese Patent No. 3641355 JP 2006-132426 A

  By the way, when the lash adjuster is installed in an engine that rotates at high speed, such as a motorcycle, the load cycle of the load by the cam is short, so after the load in the pushing direction by the cam is released, the cam further rotates and the load is loaded. Until then, the adjustment screw protrudes too little, and as a result, the movement of the adjustment screw in the protruding direction is delayed, resulting in a gap between the components of the valve gear.

  In addition, when the lash adjuster is installed in an engine that has a large inertia weight of the components of the valve gear, such as trucks and buses, the load in the pushing direction applied to the adjustment screw also increases, so the load from the cam is applied. When the adjustment screw is pushed in excessively, the movement of the adjustment screw in the protruding direction is delayed, and a gap may be generated between the constituent members of the valve gear.

  In addition, each of the above lash adjusters wears the pressure side flank of the male screw and the female screw because an impact load acts between the pressure side flank of the male screw and the female screw when a load in the pushing direction by the cam is applied to the adjusting screw. It's easy to do. When the pressure side flank of the male screw and female screw wears, the friction coefficient between the pressure side flank decreases, so the amount of adjustment screw being pushed when a load in the pushing direction is applied by the cam becomes excessive. The movement in the protruding direction of the valve is delayed, and there is a possibility that a gap is generated between the constituent members of the valve gear.

  In order to solve these problems, the inventors of the present invention studied to increase the load in the protruding direction applied from the return spring to the adjustment screw. However, each of the lash adjusters described above has a single coil for the return spring. Since it is made of a spring, if the spring constant of the return spring is increased, the size of the return spring will be excessive and will not enter the nut member. For this reason, it is difficult to increase the load in the protruding direction applied to the adjustment screw.

  The problem to be solved by the present invention is that the adjustment screw quickly moves in the protruding direction even when incorporated in an engine that rotates at high speed or when incorporated in an engine having a large inertial weight of the components of the valve gear. Another object of the present invention is to provide a lash adjuster in which the pressure side flank of the male screw and the female screw is not easily worn.

  In order to solve the above-mentioned problems, the return spring is constituted by a plurality of coil springs that overlap inside and outside. In this case, if each coil spring has a different natural frequency, it is possible to prevent resonance of the return spring.

  In addition, the above problem can be solved by urging the arm in a direction away from the protruding end of the adjusting screw with a second return spring provided so as to surround the protruding portion of the adjusting screw from the nut member. can do. In this case, if the natural frequency of the return spring is different from the natural frequency of the second return spring, resonance between the return spring and the second return spring can be prevented.

  The lash adjuster of the present invention comprising a plurality of coil springs in which the return spring overlaps inside and outside has a larger number of coil springs for biasing the adjustment screw than the lash adjuster in which the return spring is a single coil spring. Therefore, the load in the protruding direction applied to the adjustment screw is large. Therefore, even when this lash adjuster is incorporated in an engine that rotates at high speed, or when it is incorporated in an engine in which the inertia weight of the components of the valve gear is large, the adjust screw moves quickly in the protruding direction. In addition, the impact load acting on the pressure side flank between the male screw and the female screw is mitigated by the larger load in the protruding direction that is applied to the adjustment screw from the return spring than the lash adjuster in which the return spring is a single coil spring. Therefore, the pressure side flank of the male screw and the female screw is not easily worn.

  The lash adjuster according to the present invention, wherein the arm is urged in a direction away from the protruding end of the adjusting screw by a second return spring provided so as to surround the protruding portion of the adjusting screw from the nut member. When the load in the pushing direction is released, the urging force of the second return spring separates the arm from the protruding end of the adjusting screw, and the rotational resistance of the adjusting screw is reduced. Therefore, even when this lash adjuster is incorporated in an engine that rotates at high speed, or when it is incorporated in an engine in which the inertia weight of the components of the valve gear is large, the adjust screw moves quickly in the protruding direction. Further, the impact load acting between the pressure side flank of the male screw and the female screw is reduced by the amount corresponding to the urging force of the second return spring, compared to the lash adjuster without the second return spring. The flank is hard to wear.

  Also, the lash adjuster of the present invention in which the valve stem is urged in a direction away from the protruding end of the adjusting screw with a second return spring provided so as to surround the protruding portion from the nut member of the adjusting screw. When the load in the pushing direction by the cam is released, the valve stem and the protruding end of the adjusting screw are separated by the urging force of the second return spring, and the rotational resistance of the adjusting screw is reduced. Therefore, even when this lash adjuster is incorporated in an engine that rotates at high speed, or when it is incorporated in an engine in which the inertia weight of the components of the valve gear is large, the adjust screw moves quickly in the protruding direction. Further, the impact load acting between the pressure side flank of the male screw and the female screw is reduced by the amount corresponding to the urging force of the second return spring, compared to the lash adjuster without the second return spring. The flank is hard to wear.

  FIG. 1 shows a valve gear incorporating a lash adjuster 1 according to a first embodiment of the present invention. This valve operating apparatus has a valve 4 provided in an intake port 3 of an engine cylinder head 2, a valve stem 5 connected to the valve 4, and an arm 7 that swings in response to rotation of a cam 6. .

  The valve stem 5 extends upward from the valve 4 and slidably penetrates the cylinder head 2. An annular spring retainer 8 is fixed to the upper outer periphery of the valve stem 5, and a valve spring 9 is incorporated between the lower surface of the spring retainer 8 and the upper surface of the cylinder head 2. The valve spring 9 urges the valve stem 5 upward via the spring retainer 8, and the valve 4 is seated on the valve seat 10 by the urging force.

  One end of the arm 7 is supported by the lash adjuster 1, and the other end is in contact with the upper end of the valve stem 5. A roller 11 is attached to the central portion of the arm 7, and the roller 11 is in contact with a cam 6 provided above the arm 7.

  As shown in FIG. 2, the lash adjuster 1 is screwed into a cylindrical nut member 13 inserted into a receiving hole 12 opened on the upper surface of the cylinder head 2 and a female screw 14 formed on the inner periphery of the nut member 13. The adjustment screw 16 has a male screw 15 to be fitted on the outer periphery of the lower portion, and a return spring 18 incorporated between the adjustment screw 16 and the bottom portion 17 of the nut member 13.

  The male screw 15 and the female screw 14 are formed in a sawtooth shape having an asymmetric cross section along the axis, and a pressure side flank 19 that receives pressure when a load in a direction of pushing the adjusting screw 16 into the nut member 13 is applied. Is larger than the flank angle of the play side flank 20.

  The adjustment screw 16 has a protruding end 21 from the nut member 13 formed in a hemispherical shape, and the protruding end 21 is fitted in a recess 22 formed on the lower surface of the end of the arm 7. Here, the projecting end 21 is slidably in contact with the inner surface of the recess 22 of the arm 7 and supports the arm 7 so as to be swingable by the sliding.

  The return spring 18 includes two coil springs 23 and 24 that are overlapped on the inside and outside. The coil springs 23 and 24 are both supported at the lower end by the bottom portion 17 and the upper end presses the adjusting screw 16 via the spring seat 25, and the adjusting screw 16 protrudes upward from the nut member 13 by the pressing. Energized in the direction.

  The spring seat 25 has a spherical contact surface 26 that contacts the insertion end of the adjusting screw 16 into the nut member 13, and the contact surface 26 is in point contact at the rotation center of the adjusting screw 16. Further, the spring seat 25 is fitted to the upper end inner periphery of the inner coil spring 23, and the large diameter column portion 27 fitted to the upper end inner periphery of the outer coil spring 24, and extending downward from the large diameter column portion 27. The small-diameter column portion 28 and the large-diameter column portion 27 position the inner coil spring 23 and the outer coil spring 24 coaxially.

  In the two coil springs 23 and 24, the winding directions of the coils are opposite to each other, and the coil springs 23 and 24 are not entangled with each other. Further, the two coil springs 23 and 24 have different natural frequencies, thereby preventing the return spring 18 from resonating.

  Next, an operation example of the lash adjuster 1 will be described.

  When the cam 6 is rotated by the operation of the engine and the cam crest 6a of the cam 6 pushes down the arm 7, the valve 4 is separated from the valve seat 10 and the intake port 3 is opened. At this time, a load in the pushing direction is applied to the adjusting screw 16, but the pressure side flank 19 of the male screw 15 is received by the pressure side flank 19 of the female screw 14, and the axial position of the adjusting screw 16 is fixed.

  When the cam 6 further rotates and the cam crest 6a passes the position of the roller 11, the valve stem 5 is raised by the urging force of the valve spring 9, the valve 4 is seated on the valve seat 10, and the intake port 3 is close.

  Strictly speaking, when the cam crest 6a of the cam 6 pushes down the arm 7, a slight slip occurs between the pressure side flank 19 and 19 of the male screw 15 and the female screw 14, and the adjustment screw 16 moves in the pushing direction by the slip. However, when the cam crest 6a passes the position of the roller 11 and the load in the pushing direction is released, the adjustment screw 16 moves in the protruding direction by the load in the protruding direction loaded from the return spring 18, Return to the original position.

  During engine operation, when a difference in thermal expansion occurs between the components of the valve operating device such as the cylinder head 2, the valve stem 5, and the arm 7, and the distance between the cam 6 and the arm 7 increases, The amount of protrusion of the adjusting screw 16 when the cam 6 rotates and the load in the pushing direction is released is larger than the amount of pushing of the adjusting screw 16 when the cam crest 6a pushes down the arm 7. As a result, each time the cam 6 rotates, the adjustment screw 16 gradually moves in the protruding direction, so that no gap is generated between the base circle 6 b of the cam 6 and the roller 11.

  On the contrary, when the contact surface of the valve 4 and the valve seat 10 is worn, the biasing force of the valve spring 9 acts on the adjustment screw 16 even when the base circle 6b of the cam 6 is at the position of the roller 11. The amount of protrusion of the adjusting screw 16 when the cam 6 rotates and the load in the pushing direction is released is smaller than the amount of pushing of the adjusting screw 16 when the cam crest 6a of the cam 6 pushes down the arm 7. As a result, each time the cam 6 rotates, the adjustment screw 16 gradually moves in the pushing direction and the valve stem 5 rises, so that no gap is generated between the contact surfaces of the valve 4 and the valve seat 10.

  Since the lash adjuster 1 is composed of two coil springs 23 and 24 with the return spring 18 overlapping inside and outside, the return spring 18 urges the adjustment screw 16 as compared with the lash adjuster composed of a single coil spring. The number of coil springs is large, and the load in the protruding direction applied to the adjustment screw 16 is large. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 16 from when the load applied by the cam 6 is released until the cam 6 is further rotated and loaded is applied. The adjusting screw 16 can be quickly moved in the protruding direction.

  Further, the lash adjuster 1 has a large protruding load applied from the return spring 18 to the adjustment screw 16, so that the lash adjuster 1 can be used even when the lash adjuster 1 is incorporated in an engine having a large inertia weight of a valve operating device such as a truck or a bus. The pushing amount of the adjusting screw 16 when a load is applied by the cam 6 is suppressed, and the adjusting screw 16 moves quickly in the protruding direction.

  In addition, the lash adjuster 1 has a larger load in the protruding direction applied from the return spring 18 to the adjustment screw 16 than the lash adjuster in which the return spring 18 is a single coil spring. Since the impact load acting between the side flank 19 and 19 is relieved, the pressure side flank 19 of the male screw 15 and the female screw 14 is not easily worn.

  FIG. 3 shows a valve gear incorporating a lash adjuster 31 according to a second embodiment of the present invention. Similar to the first embodiment, this valve operating apparatus has a valve 34 provided in the intake port 33 of the cylinder head 32 and a valve stem 35 connected to the valve 34. The valve stem 35 extends upward from the valve 34, and a spring retainer 36 is fixed to the upper portion of the valve stem 35. The spring retainer 36 is biased upward by a valve spring 37, and the valve 34 is seated on the valve seat 38 by the biasing force.

  The lash adjuster 31 is formed on a guide hole 39 formed in the cylinder head 32 so as to be slidable up and down, a nut member 41 that moves up and down integrally with the lifter body 40, and an inner periphery of the nut member 41. The adjusting screw 44 has a male screw 43 that is engaged with the female screw 42 on the outer periphery thereof, and a return spring 45 that biases the adjusting screw 44.

  The lifter body 40 includes a cylindrical portion 46 and an end plate 47 provided at the upper end of the cylindrical portion 46. A hard shim 48 is fixed to the upper surface of the end plate 47, and a cam 49 is in contact with the shim 48. The nut member 41 is integrally formed at the center of the end plate 47, and the upper end of the nut member 41 is closed with a shim 48.

  As shown in FIG. 4, the male screw 43 and the female screw 42 are formed in a sawtooth shape having an asymmetrical cross section along the axis, and when a load in the direction of pushing the adjusting screw 44 into the nut member 41 is applied. The flank angle of the pressure side flank 50 that receives pressure is larger than the flank angle of the play side flank 51.

  The return spring 45 is composed of two coil springs 52 and 53 that overlap inside and outside. The upper ends of the coil springs 52 and 53 are both supported by a shim 48 and the lower end presses the adjusting screw 44 via the spring seat 54, and the adjusting screw 44 protrudes downward from the nut member 41 by the pressing. Energized in the direction. The protruding end of the adjustment screw 44 from the nut member 41 presses the upper end of the valve stem 35.

  The spring seat 54 has a spherical contact surface 56 that contacts a recess 55 formed at the insertion end of the adjustment screw 44 into the nut member 41, and the contact surface 56 makes point contact at the rotation center of the adjustment screw 44. ing. The spring seat 54 is fitted to the inner periphery of the lower end of the inner coil spring 53 and the large-diameter column portion 57 that fits to the inner periphery of the lower end of the outer coil spring 52. The small-diameter column part 58 and the large-diameter column part 57 position the inner coil spring 53 and the outer coil spring 52 coaxially.

  In the two coil springs 52 and 53, the winding directions of the coils are opposite to each other, and the coil springs 52 and 53 are not entangled with each other. Also, the two coil springs 52 and 53 have different natural frequencies, thereby preventing the return spring 45 from resonating.

  In the lash adjuster 31, when the cam crest 49a of the cam 49 pushes down the lifter body 40 and a load in the pushing direction is applied to the adjusting screw 44, the pressure side flank 50 of the male screw 43 is 42, the axial position of the adjusting screw 44 relative to the nut member 41 is fixed. At this time, strictly speaking, slight slip occurs between the pressure side flank 50, 50 of the male screw 43 and the female screw 42, and the adjustment screw 44 moves in the pushing direction due to the sliding, but the cam 49 further rotates to push in the pushing direction. When the load is released, the adjustment screw 44 is moved in the protruding direction by the load in the protruding direction applied from the return spring 45 and returns to the original position.

  The lash adjuster 31 is composed of two coil springs 52 and 53 with the return spring 45 overlapping inside and outside, so that the return spring 45 biases the adjustment screw 44 as compared with the lash adjuster composed of a single coil spring. The number of coil springs is large, and the load in the protruding direction applied to the adjustment screw 44 is large. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 44 from when the load by the cam 49 is released until the cam 49 is further rotated and the load is applied. The adjustment screw 44 can be quickly moved in the protruding direction.

  Further, the lash adjuster 31 has a large protruding load applied from the return spring 45 to the adjustment screw 44, so that the lash adjuster 31 can be used even when the lash adjuster 31 is incorporated in an engine having a large inertia weight of a valve operating device such as a truck or a bus. The pushing amount of the adjusting screw 44 when the load by the cam 49 is applied is suppressed, and the adjusting screw 44 moves quickly in the protruding direction.

  Further, the lash adjuster 31 has a larger pressure in the protruding direction that is applied from the return spring 45 to the adjustment screw 44 than the lash adjuster in which the return spring 45 is a single coil spring. Since the impact load acting between the side flank 50 and 50 is reduced, the pressure side flank 50 of the male screw 43 and the female screw 42 is not easily worn.

  In this embodiment, the nut member 41 and the lifter body 40 are integrally formed. However, the nut member 41 may be formed separately from the lifter body 40 and the nut member 41 may be fixed to the lifter body 40. In short, the nut member 41 may be moved up and down integrally with the lifter body 40 when the lifter body 40 is moved up and down.

  FIG. 5 shows a valve gear incorporating a lash adjuster 61 according to a third embodiment of the present invention. This valve operating apparatus has a valve 64 provided in an intake port 63 of a cylinder head 62 of the engine, a valve stem 65 connected to the valve 64, and an arm 67 that swings according to the rotation of a cam 66. . The valve stem 65 extends upward from the valve 64, and a spring retainer 68 is fixed to the upper portion of the valve stem 65. The spring retainer 68 is biased upward by a valve spring 69, and the valve 64 is seated on the valve seat 70 by the biasing force.

  The arm 67 is supported at the center by a fulcrum shaft 71 so as to be swingable. A roller 72 that contacts the cam 66 is attached to one end of the arm 67, and a lash adjuster 61 is incorporated into the other end of the arm 67.

  As shown in FIG. 6, the lash adjuster 61 includes a nut member 73, an adjustment screw 74, and a return spring 75. The nut member 73 is inserted into a receiving hole 76 that vertically penetrates the arm 67, and a female screw 77 formed on the inner periphery of the nut member 73 is engaged with a male screw 78 formed on the outer periphery of the adjusting screw 74. is doing.

  The male screw 78 and the female screw 77 are formed in a sawtooth shape having an asymmetric cross section along the axis, and a pressure side flank 79 that receives pressure when a load in a direction of pushing the adjusting screw 74 into the nut member 73 is applied. Is larger than the flank angle of the play side flank 80.

  The upper end of the nut member 73 protrudes from the upper surface of the arm 67, and a bottomed cylindrical cap 81 is fitted and fixed to the protruding portion. The cap 81 is locked to the upper edge of the accommodation hole 76 to prevent the nut member 73 from dropping downward from the accommodation hole 76. On the other hand, a flange 82 that contacts the lower surface of the arm 67 is formed at the lower end of the nut member 73, and the upward force acting on the nut member 73 is received by the flange 82.

  The return spring 75 includes two coil springs 83 and 84 that are overlapped inside and outside. The coil springs 83 and 84 are both supported at the upper end by the cap 81, and the lower end presses the adjustment screw 74 via the spring seat 85, and the adjustment screw 74 protrudes downward from the nut member 73 by the pressing. Energized in the direction. The protruding end of the adjusting screw 74 from the nut member 73 presses the upper end of the valve stem 65.

  The spring seat 85 has a spherical contact surface 86 that comes into contact with the insertion end of the adjustment screw 74 into the nut member 73, and the contact surface 86 is in point contact at the rotation center of the adjustment screw 74. Further, the spring seat 85 is fitted to the inner periphery of the lower end of the inner coil spring 83 and the large diameter column portion 87 fitted to the inner periphery of the lower end of the outer coil spring 84 and extending upward from the larger diameter column portion 87. The inner diameter coil spring 83 and the outer diameter coil spring 84 are coaxially positioned by the small diameter column section 88 and the large diameter column section 87.

  In the two coil springs 83 and 84, the winding directions of the coils are opposite to each other, and the coil springs 83 and 84 are not entangled with each other. Also, the two coil springs 83 and 84 have different natural frequencies, thereby preventing the return spring 75 from resonating.

  In the lash adjuster 61, when the cam crest 66a of the cam 66 pushes up the end of the arm 67 and a load in the pushing direction is applied to the adjusting screw 74, as in the first embodiment, the pressure side flank of the male screw 78 is applied. 79 is received by the pressure side flank 79 of the female screw 77, and the axial position of the adjusting screw 74 with respect to the nut member 73 is fixed. At this time, strictly speaking, a slight slip occurs between the pressure side flank 79 and 79 of the male screw 78 and the female screw 77, and the adjustment screw 74 moves in the pushing direction due to the sliding, but the cam 66 further rotates and pushes in the pushing direction. When the load is released, the adjustment screw 74 is moved in the protruding direction by the load in the protruding direction loaded from the return spring 75 and returns to the original position.

  Since the lash adjuster 61 is composed of two coil springs 83 and 84 with the return spring 75 overlapping inside and outside, the return spring 75 biases the adjustment screw 74 as compared with the lash adjuster composed of a single coil spring. The number of coil springs is large, and the load in the protruding direction applied to the adjustment screw 74 is large. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 74 from when the load by the cam 66 is released until the cam 66 is further rotated and loaded is applied. The adjustment screw 74 can be quickly moved in the protruding direction.

  The lash adjuster 61 has a large protruding load applied from the return spring 75 to the adjustment screw 74. Therefore, even when the lash adjuster 61 is incorporated in an engine having a large inertia weight of a component of a valve operating device such as a truck or a bus. The pushing amount of the adjusting screw 74 when the load by the cam 66 is applied is suppressed, and the adjusting screw 74 moves quickly in the protruding direction.

  Further, the lash adjuster 61 has a larger load in the protruding direction applied from the return spring 75 to the adjustment screw 74 than the lash adjuster in which the return spring 75 is a single coil spring. Since the impact load acting between the side flank 79 and 79 is relieved, the pressure side flank 79 of the male screw 78 and the female screw 77 is hardly worn.

  7 and 8 show a valve gear incorporating a lash adjuster 91 according to a fourth embodiment of the present invention. Portions corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The lash adjuster 91 includes a nut member 13, an adjustment screw 16, a return spring 92, and a second return spring 93.

  The return spring 92 is composed of a single coil spring. The return spring 92 has a lower end supported by the bottom portion 17 and an upper end pressing the adjustment screw 16 via the spring seat 94, and the adjustment screw 16 protrudes upward from the nut member 13 by the pressing. Energized.

  The second return spring 93 is also a coil spring, and is provided so as to surround a protruding portion of the adjustment screw 16 from the nut member 13. The second return spring 93 is supported at the lower end by the upper end surface of the nut member 13, and the upper end presses the lower surface of the arm 7, and the arm 7 is separated from the protruding end 21 of the adjusting screw 16 by the pressing. Energized in the direction.

  The return spring 92 and the second return spring 93 have different natural frequencies, thereby preventing resonance between the return spring 92 and the second return spring 93.

  When the load in the pushing direction by the cam 6 is released, the lash adjuster 91 separates the arm 7 from the protruding end 21 of the adjusting screw 16 by the urging force of the second return spring 93, and the rotational resistance of the adjusting screw 16. Becomes smaller. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 16 from when the load applied by the cam 6 is released until the cam 6 is further rotated and loaded is applied. The adjusting screw 16 can be quickly moved in the protruding direction.

  Further, the lash adjuster 91 has a cam camshaft that is incorporated into an engine having a large inertia weight of a component of a valve operating device, such as a truck or a bus, as compared with a case where the lash adjuster 91 is incorporated into an engine having a small inertia weight of a component of a valve operating device. The amount by which the adjusting screw 16 is pushed when the load by the load 6 is applied increases. However, the load of the adjusting screw 16 after the load by the cam 6 is released and until the load is further applied by the rotation of the cam 6 is increased. Since the protruding amount is also increased, the adjusting screw 16 moves quickly in the protruding direction.

  Further, the lash adjuster 91 has an impact acting between the pressure side flank 19, 19 of the male screw 15 and the female screw 14 by an amount corresponding to the urging force of the second return spring 93 than the lash adjuster without the second return spring 93. Since the load is relaxed, the pressure side flank 19 of the male screw 15 and the female screw 14 is not easily worn.

  Further, the lash adjuster 91 is configured so that when the load in the pushing direction by the cam 6 is released, the concave portion 22 of the arm 7 and the protruding end 21 of the adjustment screw 16 are separated by the urging force of the second return spring 93. 2 The recessed portion 22 of the arm 7 and the protruding end 21 of the adjusting screw 16 are less likely to wear than the lash adjuster without the return spring 93.

  Further, since the lash adjuster 91 supports the lower end of the second return spring 93 by the upper end of the nut member 13, it is possible to prevent the nut member 13 from floating from the bottom of the accommodation hole 12 during engine operation. .

  In this embodiment, the arm 7 is biased by the second return spring 93 supported by the upper end of the nut member 13, but as shown in FIG. 9, the second return spring 95 supported by the upper surface of the cylinder head 2 is used. The arm 7 may be biased. In short, it is only necessary to urge the arm 7 in a direction away from the protruding end 21 of the adjusting screw 16 with a second return spring provided so as to surround the protruding portion of the adjusting screw 16 from the nut member 13.

  In this embodiment, a return spring 92 made of a single coil spring is used as a return spring for urging the adjustment screw 16 in a direction protruding upward from the nut member 13, but instead of the return spring 92, You may use the return spring (For example, the return spring 18 of 1st Embodiment) which consists of several coil springs which overlap inside and outside.

  FIG. 10 shows a valve gear incorporating a lash adjuster 101 according to the fifth embodiment of the present invention. Portions corresponding to the second embodiment are denoted by the same reference numerals and description thereof is omitted.

  The lash adjuster 101 includes a lifter body 40, a nut member 41, an adjustment screw 44, a return spring 102, and a second return spring 103.

  The return spring 102 is composed of a single coil spring. The return spring 102 is supported at its upper end by a shim 48, and its lower end presses the adjustment screw 44 via the spring seat 104, and the adjustment screw 44 is biased in a direction protruding downward from the nut member 41 by the pressing. is doing.

  The second return spring 103 is also a coil spring, and is provided so as to surround the protruding portion of the adjustment screw 44 from the nut member 41. The upper end of the second return spring 103 is supported by the lower end surface of the nut member 41, and the lower end presses the upper surface of the spring retainer 36, and the valve stem 35 is separated from the protruding end of the adjustment screw 44 by the pressing. It is energizing in the direction to do.

  The return spring 102 and the second return spring 103 have different natural frequencies, thereby preventing resonance between the return spring 102 and the second return spring 103.

  When the load in the pushing direction by the cam 49 is released, the lash adjuster 101 separates the valve stem 35 from the protruding end of the adjustment screw 44 by the urging force of the second return spring 103, and the rotational resistance of the adjustment screw 44. Becomes smaller. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 44 from when the load by the cam 49 is released until the cam 49 is further rotated and the load is applied. The adjustment screw 44 can be quickly moved in the protruding direction.

  In addition, the lash adjuster 101 has a cam camshaft that is incorporated into an engine having a large inertial weight of a component of a valve operating device, such as a truck or a bus, as compared with a case of being incorporated into an engine having a small inertial weight of a component of a valve operating device. The amount by which the adjustment screw 44 is pushed when the load by 49 is applied increases, but the adjustment screw 44 is not yet loaded until the load is applied by the rotation of the cam 49 after the load by the cam 49 is released. The protruding amount also increases, and the adjustment screw 44 moves quickly in the protruding direction.

  Further, this lash adjuster 101 reduces the impact load acting between the pressure side flank of the male screw 43 and the female screw 42 by an amount corresponding to the urging force of the second return spring 103 than the lash adjuster without the second return spring 103. Therefore, the pressure side flank of the male screw 43 and the female screw 42 is not easily worn.

  Further, the lash adjuster 101 separates the valve stem 35 and the protruding end of the adjustment screw 44 by the biasing force of the second return spring 103 when the load in the pushing direction by the cam 49 is released. The valve stem 35 and the protruding end of the adjustment screw 44 are less likely to wear than the lash adjuster without 103.

  In this embodiment, the return spring 102 made of a single coil spring is used as a return spring that urges the adjustment screw 44 in a direction protruding downward from the nut member 41. You may use the return spring (for example, return spring 45 of 2nd Embodiment) which consists of a plurality of coil springs which overlap.

  FIG. 11 shows a valve gear incorporating a lash adjuster 111 according to the sixth embodiment of the present invention. Portions corresponding to the third embodiment are denoted by the same reference numerals and description thereof is omitted.

  The lash adjuster 111 includes a nut member 73, an adjustment screw 74, a return spring 112, and a second return spring 113.

  The return spring 112 is a single coil spring. The return spring 112 has an upper end supported by the cap 81 and a lower end pressing the adjustment screw 74 via the spring seat 114, and the adjustment screw 74 protrudes downward from the nut member 73 by the pressing. Energized.

  The second return spring 113 is also a coil spring, and is provided so as to surround a protruding portion of the adjustment screw 74 from the nut member 73. The second return spring 113 has an upper end supported by the lower end surface of the nut member 73 and a lower end pressing the upper surface of the spring retainer 68, and the valve stem 65 is separated from the protruding end of the adjustment screw 74 by the pressing. It is energizing in the direction to do.

  The return spring 112 and the second return spring 113 have different natural frequencies, thereby preventing resonance between the return spring 112 and the second return spring 113.

  When the load in the pushing direction by the cam 66 is released, the lash adjuster 111 separates the valve stem 65 from the protruding end of the adjustment screw 74 by the urging force of the second return spring 113, and the rotational resistance of the adjustment screw 74 is reduced. Becomes smaller. Therefore, even when incorporated in an engine that rotates at high speed, such as a motorcycle, the amount of protrusion of the adjusting screw 74 from when the load by the cam 66 is released until the cam 66 is further rotated and loaded is applied. The adjustment screw 74 can be quickly moved in the protruding direction.

  In addition, the lash adjuster 111 has a cam camshaft that is incorporated into an engine having a large inertia weight of a component of a valve operating device such as a truck or a bus, as compared with a case where the lash adjuster 111 is incorporated into an engine having a small inertia weight of a component of a valve operating device. The amount by which the adjustment screw 74 is pushed when a load is applied is increased. However, the adjustment screw 74 is not rotated until the cam 66 is further rotated and the load is applied after the load by the cam 66 is released. Since the protruding amount is also increased, the adjustment screw 74 moves quickly in the protruding direction.

  Further, the lash adjuster 111 reduces the impact load acting between the pressure side flank of the male screw 78 and the female screw 77 by an amount corresponding to the urging force of the second return spring 113 than the lash adjuster without the second return spring 113. Therefore, the pressure side flank of the male screw 78 and the female screw 77 is not easily worn.

  In addition, the lash adjuster 111 separates the valve stem 65 from the protruding end of the adjustment screw 74 by the urging force of the second return spring 113 when the load in the pushing direction by the cam 66 is released. The valve stem 65 and the protruding end of the adjustment screw 74 are less likely to wear than the lash adjuster without the 113.

  In this embodiment, the return spring 112 made of a single coil spring is used as a return spring that urges the adjusting screw 74 in a direction protruding downward from the nut member 73. A return spring composed of a plurality of overlapping coil springs (for example, the return spring 75 of the third embodiment) may be used.

The front view which shows the valve operating apparatus incorporating the lash adjuster of 1st Embodiment of this invention 1 is an enlarged cross-sectional view near the lash adjuster in FIG. The front view which shows the valve operating apparatus incorporating the lash adjuster of 2nd Embodiment of this invention. Fig. 3 is an enlarged cross-sectional view near the return spring. Front view showing a valve gear incorporating a lash adjuster according to a third embodiment of the present invention. Fig. 5 is an enlarged cross-sectional view near the lash adjuster. Front view showing a valve gear incorporating a lash adjuster according to a fourth embodiment of the present invention. FIG. 7 is an enlarged sectional view near the lash adjuster. FIG. 8 is an enlarged sectional view in the vicinity of a lash adjuster showing a modification of the second return spring of FIG. Front view showing a valve gear incorporating a lash adjuster according to a fifth embodiment of the present invention. Front view showing a valve gear incorporating a lash adjuster according to a sixth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 2 Cylinder head 7 Arm 12 Accommodating hole 13 Nut member 14 Female screw 15 Male screw 16 Adjustment screw 18 Return spring 21 Projection end 23, 24 Coil spring 31 Rush adjuster 32 Cylinder head 35 Valve stem 39 Guide hole 40 Lifter body 41 Nut member 42 Female screw 43 Male screw 44 Adjust screw 45 Return spring 52, 53 Coil spring 61 Rush adjuster 65 Valve stem 66 Cam 67 Arm 73 Nut member 74 Adjust screw 75 Return spring 76 Housing hole 77 Female screw 78 Male screw 83, 84 Coil spring 91 Rush adjuster 92 Return Spring 93 Second return spring 101 Rush adjuster 102 Return spring 103 Second Rita Down spring 111 lash adjuster 112 return spring 113 second return spring

Claims (8)

  A nut member (13) to be inserted into the accommodation hole (12) opened on the upper surface of the cylinder head (2), and a male screw (14) that engages with a female screw (14) formed on the inner periphery of the nut member (13). 15) an adjustment screw (16) having an outer periphery, and a return spring (18) for urging the adjustment screw (16) in a direction protruding upward from the nut member (13), the adjustment screw (16) ) In the lash adjuster (1) that supports the arm (7) of the valve gear so as to be swingable by the projecting end (21) from the nut member (13), a plurality of the return springs (18) overlap with each other. Rush adjuster characterized by comprising coil springs (23, 24).   A lifter body (40) slidably inserted into a guide hole (39) formed in the cylinder head (32), a nut member (41) that moves up and down integrally with the lifter body (40), and the nut member An adjustment screw (44) having a male screw (43) that engages with a female screw (42) formed on the inner periphery of (41) on the outer periphery, and the adjustment screw (44) protruding downward from the nut member (41) A lash adjuster (31) for pressing the valve stem (35) of the valve gear with a protruding end from the nut member (41) of the adjusting screw (44). And the return spring (45) comprises a plurality of coil springs (52, 53) overlapping inward and outward. Yasuta.   A nut member (73) inserted into a receiving hole (76) opened in the lower surface of the arm (67) that swings according to the rotation of the cam (66), and formed on the inner periphery of the nut member (73) An adjustment screw (74) having a male screw (78) on the outer periphery thereof that engages with the female screw (77), and a return spring (75) that urges the adjustment screw (74) in a direction that protrudes downward from the nut member (73). In the lash adjuster (61) that presses the valve stem (65) of the valve gear with the protruding end from the nut member (73) of the adjustment screw (74), the return spring (75) A lash adjuster characterized by comprising a plurality of coil springs (83, 84) which overlap inside and outside.   The lash adjuster according to any one of claims 1 to 3, wherein the natural frequencies of the plurality of coil springs (23, 24) are different from each other.   A nut member (13) to be inserted into the accommodation hole (12) opened on the upper surface of the cylinder head (2), and a male screw (14) that engages with a female screw (14) formed on the inner periphery of the nut member (13). 15) an adjustment screw (16) having an outer periphery thereof, and a return spring (92) for urging the adjustment screw (16) in a direction protruding upward from the nut member (13), the adjustment screw (16) ) In the lash adjuster (91) that supports the arm (7) of the valve gear so as to be swingable by the projecting end (21) from the nut member (13), from the nut member (13) of the adjustment screw (16). A second return spring (93) provided so as to surround the protruding portion of the adjusting screw (16) separates the arm (7) from the protruding end (21) of the adjusting screw (16). Lash adjuster characterized by being biased in a direction to.   A lifter body (40) slidably inserted into a guide hole (39) formed in the cylinder head (32), a nut member (41) that moves up and down integrally with the lifter body (40), and the nut member An adjustment screw (44) having a male screw (43) that engages with a female screw (42) formed on the inner periphery of (41) on the outer periphery, and the adjustment screw (44) protruding downward from the nut member (41) A lash adjuster (101) for pressing the valve stem (35) of the valve gear with a protruding end from the nut member (41) of the adjusting screw (44). The second return spring (1) provided so as to surround the protruding portion of the adjustment screw (44) from the nut member (41). 3), lash adjuster, characterized in that said valve stem (35) and urged in a direction away from the protruding end of the adjusting screw (44).   A nut member (73) inserted into a receiving hole (76) opened in the lower surface of the arm (67) that swings according to the rotation of the cam (66), and formed on the inner periphery of the nut member (73) An adjustment screw (74) having a male screw (78) engaged with the female screw (77) on the outer periphery, and a return spring (112) for urging the adjustment screw (74) in a direction protruding downward from the nut member (73) In a lash adjuster (111) that presses the valve stem (65) of the valve gear with the protruding end of the adjust screw (74) from the nut member (73), the nut of the adjust screw (74) A second return spring (113) provided so as to surround the projecting portion from the member (73), and the valve stem (65) is connected to the adjustment screw. Lash adjuster characterized by being biased in a direction away from the protruding end (74).   The lash adjuster according to any one of claims 5 to 7, wherein a natural frequency of the return spring (92) is different from a natural frequency of the second return spring (93).

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