JP2009108801A - Rush adjuster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an adjust screw in a rush adjuster from coming off from a nut member due to a biasing force of a return spring. <P>SOLUTION: A rush adjuster includes a nut member 13 inserted into an accommodating hole 16 opening to the top face of a cylinder head 2, an adjust screw 14 having a male thread 18 at its outer circumference engaged with the female thread 17 formed at the inner circumference of the nut member 13 and a return spring 15 for biasing the adjust screw 14 in an upwardly protruding direction from the nut member 13, and rockingly supports an arm 6 of a valve gear with the adjust screw 14, wherein the male thread 18 and the female thread 17 are engaged with each other at the length of one pitch or longer when the adjust screw 14 is projected until the return spring 15 is restored to a natural length. <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 devices), a valve lifter supported so as to be slidable up and down by a cam, and a valve stem pushed down by the valve lifter (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 gap.

  In order to prevent this abnormal noise and compression leakage, a lash adjuster is often incorporated in the valve operating device, and the lash adjuster often absorbs a change in the gap between the 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 adjustment screw having a male screw on its outer periphery, and a return spring that urges the adjustment screw in a direction protruding upward from the nut member, and the adjustment screw supports the arm of the valve gear so that it can swing. Is known (Patent Document 1).

  Further, 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 fixed to the lifter body, and an inner periphery of the nut member. An adjusting screw having a male screw on its outer periphery that engages with the female screw, and a return spring that urges the adjusting screw in a direction protruding downward from the nut member, and the valve stem of the valve operating device with the adjusting screw. 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 that urges the adjusting screw in a direction protruding downward from the nut member, and pressing the valve stem of the valve operating device with the adjusting screw. Known (Patent Document 3).
JP 2005-273510 A JP 2003-227318 A JP 2006-132426 A

  By the way, when the lash adjuster is subjected to vibration when the camshaft or the arm is removed from the valve gear during engine assembly, the lash adjuster protrudes by the urging force of the return spring and falls off the nut member. There was a fear. When the adjusting screw falls off, parts (such as return springs and spring seats) incorporated in the nut member often fall off together with the adjusting screw, and it is complicated to collect and reassemble these parts.

  Similarly, during engine maintenance, when the camshaft or arm is removed from the valve gear, the adjustment screw may protrude due to the biasing force of the return spring and fall off the nut member. However, the adjustment screw may fall off due to the urging force of the return spring.

  The problem to be solved by the present invention is to prevent the adjustment screw of the lash adjuster from falling off the nut member due to the urging force of the return spring.

  In order to solve the above problem, the male screw and the female screw are engaged with each other with a length of at least one pitch when the adjustment screw is projected until the return spring is restored to its natural length.

This lash adjuster can have the following configuration.
1) The male screw and the female screw are multi-threaded screws.
2) The male screw and the female screw are formed such that the flank angle of the pressure-side flank that receives pressure when a force in the direction of pushing the adjusting screw into the nut member is larger than the flank angle of the play-side flank.
3) The return spring is a coil spring.

  In the lash adjuster according to the present invention, even when the adjustment screw protrudes until the return spring is restored to the natural length, the male screw of the adjustment screw and the female screw of the nut member are screw-engaged with a length of at least one pitch. Therefore, it is possible to prevent the adjustment screw from falling off the nut member due to the urging force of the return spring.

  FIG. 1 shows a valve gear incorporating a lash adjuster 1 according to a first embodiment of the present invention. This valve operating apparatus includes 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 6 that is swingably supported by a lash adjuster 1. Have.

  The valve stem 5 extends upward from the valve 4 and slidably penetrates the cylinder head 2. An annular spring retainer 7 is fixed to the upper outer periphery of the valve stem 5, and a valve spring 8 is incorporated between the lower surface of the spring retainer 7 and the upper surface of the cylinder head 2. The valve spring 8 urges the spring retainer 7 upward, and the valve 4 is seated on the valve seat 9 by the urging force.

  One end of the arm 6 is supported by the lash adjuster 1 so as to be swingable, and the other end is in contact with the upper end of the valve stem 5. A cam 11 fixed to the camshaft 10 is provided above the arm 6. In the cam 11, when the cam shaft 10 rotates, a cam crest portion 11 b raised with respect to the base circle 11 a presses the roller 12 provided at the center of the arm 6 to push down the arm 6.

  The lash adjuster 1 includes a nut member 13, an adjustment screw 14, and a return spring 15. The nut member 13 is inserted into the accommodation hole 16 opened on the upper surface of the cylinder head 2.

  As shown in FIG. 2, two female threads 17 formed on the inner periphery of the nut member 13 are screw-engaged with two male threads 18 formed on the outer periphery of the adjusting screw 14. The male screw 18 and the female screw 17 are formed in a sawtooth shape having an asymmetric cross section along the axis, and the pressure side flank 19 that receives pressure when a force in the direction of pushing the adjusting screw 14 into the nut member 13 is applied. The flank angle is larger than the flank angle of the play side flank 20.

  A bottom member 21 is fixed to the lower end of the nut member 13. The return spring 15 is incorporated between the adjustment screw 14 and the bottom member 21, and biases the adjustment screw 14 in a direction of protruding upward from the nut member 13 via the spring seat 22. The return spring 15 is a coil spring, and the natural length of the return spring 15 is that when the adjustment screw 14 protrudes from the nut member 13 and the return spring 15 is restored to the natural length as shown in FIG. The length is set so that the screw engages with a length of at least one pitch.

  The adjusting screw 14 has a projecting end 23 from the nut member 13 in a hemispherical shape, and the projecting end 23 is fitted into a recess 24 formed on the lower surface of the arm 6 as shown in FIG. 6 is supported in a swingable manner.

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

  When the camshaft 10 is rotated by the operation of the engine and the cam crest 11b of the cam 11 pushes down the arm 6, the valve 4 is separated from the valve seat 9 and the intake port 3 is opened. At this time, a force in the pushing direction acts on the adjusting screw 14, but the pressure side flank 19 of the male screw 18 is received by the pressure side flank 19 of the female screw 17, so that the axial position of the adjusting screw 14 is fixed.

  Further, when the camshaft 10 rotates and the cam crest 11b passes the position of the roller 12, the valve stem 5 is raised by the urging force of the valve spring 8, the valve 4 is seated on the valve seat 9, and the intake port Close 3

  Strictly speaking, when the cam crest portion 11b of the cam 11 pushes down the arm 6, a slight slip occurs between the pressure side flank 19 of the male screw 18 and the pressure side flank 19 of the female screw 17, but the cam crest portion 11b Since the load in the pushing direction acting on the adjustment screw 14 is released after the position of the roller 12 passes through the position of the roller 12 again, the position of the adjustment screw 14 is restored by the urging force of the return spring 15. Return to.

  Further, 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 6 during engine operation, and the distance between the cam 11 and the arm 6 increases, the return Since the adjusting screw 14 moves in the protruding direction while being rotated by the urging force of the spring 15, there is no gap between the base circle 11 a of the cam 11 and the roller 12.

  On the contrary, when the contact surface of the valve 4 and the valve seat 9 is worn, the urging force of the valve spring 8 is applied to the adjusting screw 14 as a pushing load even when the base circle 11a of the cam 11 is at the position of the roller 12. In order to continue, the minute slip generated between the pressure side flank 19 of the male screw 18 and the pressure side flank 19 of the female screw 17 generated when the cam crest 11b passes the position of the roller 12 is accumulated, and the adjusting screw 14 is pushed in. Move slowly to. As a result, the valve stem 5 is raised, so that no gap is generated between the contact surfaces of the valve 4 and the valve seat 9.

  In the lash adjuster 1, when vibration is applied to the adjustment screw 14 with the camshaft 10 removed from the valve gear during assembly of the engine, the adjustment screw 14 protrudes due to the urging force of the return spring 15. Even if the return spring 15 protrudes until it is elastically restored to its natural length, the screw engagement between the male screw 18 and the female screw 17 is maintained, so that the adjusting screw 14 does not fall off the nut member 13.

  Also, when the camshaft 10 and the arm 6 are removed from the valve gear for maintenance of the engine, the adjustment screw 14 may protrude due to the urging force of the return spring 15. Since the screw engagement of the female screw 17 is maintained, the adjustment screw 14 does not fall off the nut member 13. Similarly, the adjustment screw 14 does not fall off from the nut member 13 when the lash adjuster 1 is transported before being assembled to the valve gear.

  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 includes a lifter body 39, a nut member 40, an adjustment screw 41, and a return spring 42. The lifter body 39 is inserted into a guide hole 43 formed in the cylinder head 32 so as to be slidable up and down. The lifter body 39 includes a cylindrical portion 39a and an end plate 39b that closes the upper end of the cylindrical portion 39a.

  Above the lifter body 39, a cam 45 fixed to the cam shaft 44 is provided. In the cam 45, when the cam shaft 44 rotates, a cam peak portion 45b raised with respect to the base circle 45a presses the upper surface of the end plate 39b to push down the lifter body 39.

  As shown in FIG. 4, the nut member 40 is fixed to the lower surface of the end plate 39 b with a retaining ring 46, and two female screws 47 formed on the inner periphery of the nut member 40 are formed on the outer periphery of the adjustment screw 41. The two male threads 48 formed are threadedly engaged. In the male screw 48 and the female screw 47, the flank angle of the pressure-side flank 49 that receives pressure when a force in the direction of pushing the adjusting screw 41 into the nut member 40 is larger than the flank angle of the play-side flank 50.

  The return spring 42 is incorporated between the adjustment screw 41 and the end plate 39b, and urges the adjustment screw 41 in a direction protruding downward from the nut member 40. The return spring 42 is a coil spring, and the natural length of the return spring 42 is that when the adjustment screw 41 is protruded from the nut member 40 and the return spring 42 is restored to the natural length as shown in FIG. The length is set so that the screw engages with a length of at least one pitch.

  The protruding end of the adjustment screw 41 from the nut member 40 presses the upper end of the valve stem 35 as shown in FIG.

  As in the first embodiment, the lash adjuster 31 projects the adjustment screw 41 by the urging force of the return spring 42 when vibration is applied with the camshaft 44 removed from the valve gear during engine assembly or maintenance. However, at this time, even if the return spring 42 protrudes until it is elastically restored to its natural length, the screw engagement between the male screw 48 and the female screw 47 is maintained, so that the adjustment screw 41 does not fall off from the nut member 40.

  Further, even when the lash adjuster 31 is extracted from the guide hole 43, the adjustment screw 41 may protrude due to the urging force of the return spring 42. In this case, the screw engagement between the male screw 48 and the female screw 47 is maintained. Therefore, the adjusting screw 41 does not fall off from the nut member 40.

  FIG. 5 shows a valve gear incorporating a lash adjuster 51 according to a third embodiment of the present invention. This valve operating apparatus includes a valve 54 provided in an intake port 53 of a cylinder head 52 of an engine, a valve stem 55 connected to the valve 54, and an arm 57 supported so as to be swingable about a fulcrum shaft 56. And have.

  The valve stem 55 extends upward from the valve 54, and a spring retainer 58 is fixed to the upper portion of the valve stem 55. The spring retainer 58 is urged upward by a valve spring 59, and the valve 54 is seated on the valve seat 60 by the urging force.

  The center of the arm 57 is supported by a fulcrum shaft 56 so as to be swingable. A roller 61 is attached to one end of the arm 57, and a lash adjuster 51 is incorporated in the other end. A cam 63 fixed to the camshaft 62 is provided below the arm 57. The cam 63 is configured such that when the cam shaft 62 rotates, a cam crest 63b raised with respect to the base circle 63a presses the roller 61 to swing the arm 57.

  As shown in FIG. 6, the lash adjuster 51 includes a nut member 64, an adjustment screw 65, and a return spring 66. The nut member 64 is inserted into a receiving hole 67 penetrating the arm 57 in the vertical direction, and two female screws 68 formed on the inner periphery of the nut member 64 are formed on the two screws formed on the outer periphery of the adjusting screw 65. The male screw 69 is engaged with the screw.

  The upper end of the nut member 64 protrudes from the upper surface of the arm 57, and a bottomed cylindrical cap 70 is fitted and fixed to the protruding portion. The cap 70 is locked to the upper edge of the receiving hole 67 to prevent the nut member 64 from dropping downward from the receiving hole 67. On the other hand, a flange 71 that abuts the lower surface of the arm 57 is formed at the lower end of the nut member 64, and the upward force acting on the nut member 64 is received by the flange 71.

  In the male screw 69 and the female screw 68, the flank angle of the pressure side flank 72 that receives pressure when a force in the direction of pushing the adjusting screw 65 into the nut member 64 is larger than the flank angle of the play side flank 73.

  The return spring 66 is incorporated between the cap 70 and the adjustment screw 65, and urges the adjustment screw 65 in a direction protruding downward from the nut member 64. The return spring 66 is a coil spring, and the natural length of the return spring 66 is that when the adjust screw 65 protrudes from the nut member 64 and the return spring 66 is restored to the natural length as shown in FIG. The length is set so that the screw engages with a length of at least one pitch.

  The protruding end of the adjusting screw 65 from the nut member 64 presses the upper end of the valve stem 55 as shown in FIG.

  In the lash adjuster 51, when vibration is applied with the arm 57 removed from the valve gear during engine assembly or maintenance, the adjust screw 65 protrudes by the urging force of the return spring 66, as in the first embodiment. However, at this time, even if the return spring 66 protrudes until it is elastically restored to its natural length, the screw engagement between the male screw 69 and the female screw 68 is maintained, so that the adjusting screw 65 does not fall off the nut member 64. Further, the adjustment screw 65 does not fall off from the nut member 64 when the lash adjuster 51 is transported before being assembled to the valve gear.

The front view which shows the valve operating apparatus incorporating the lash adjuster of 1st Embodiment of this invention FIG. 1 is an enlarged cross-sectional view showing a state in which the adjustment screw protrudes until the return spring of the lash adjuster shown in FIG. 1 is restored to its natural length. 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 showing a state in which the adjustment screw protrudes until the return spring of the lash adjuster shown in FIG. 3 is restored to its natural length. 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 showing a state where the adjustment screw protrudes until the return spring of the lash adjuster shown in FIG. 5 is restored to its natural length.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 2 Cylinder head 6 Arm 13 Nut member 14 Adjustment screw 15 Return spring 16 Housing hole 17 Female screw 18 Male screw 19 Pressure side flank 20 Play side flank 31 Rush adjuster 32 Cylinder head 35 Valve stem 39 Lifter body 40 Nut member 41 Adjust screw 42 Return spring 43 Guide hole 47 Female screw 48 Male screw 49 Pressure side flank 50 Play side flank 51 Rush adjuster 55 Valve stem 57 Arm 63 Cam 64 Nut member 65 Adjust screw 66 Return spring 67 Housing hole 68 Female screw 69 Male screw 72 Pressure side flank 73 Play side Frank

Claims (6)

  A nut member (13) to be inserted into the accommodation hole (16) opened in the upper surface of the cylinder head (2), and a male screw (17) that engages with a female screw (17) formed on the inner periphery of the nut member (13). 18) an adjustment screw (14) having an outer periphery, and a return spring (15) for biasing the adjustment screw (14) in a direction protruding upward from the nut member (13). 14) In the lash adjuster (1) that supports the arm (6) of the valve gear so as to be swingable in 14), when the adjustment screw (14) is protruded until the return spring (15) is restored to its natural length. The lash adjuster characterized in that the male screw (18) and the female screw (17) are screw-engaged with a length of at least one pitch.   A lifter body (39) that is slidably inserted into a guide hole (43) formed in the cylinder head (32), a nut member (40) fixed to the lifter body (39), and a nut member (40 ) And an adjust screw (41) having a male screw (48) on its outer periphery that engages with a female screw (47) formed on the inner periphery, and the adjust screw (41) projecting downward from the nut member (40). In the lash adjuster (31) having a return spring (42) biased in the direction and pressing the valve stem (35) of the valve operating device with the adjustment screw (41), the return spring (42) has a natural length. When the adjustment screw (41) is protruded until it is restored to the minimum, the male screw (48) and the female screw (47) are at least Lash adjuster is characterized in that so as to threadingly engage with one pitch or more in length.   A nut member (64) inserted into a receiving hole (67) opened in the lower surface of the arm (57) that swings according to the rotation of the cam (63), and formed on the inner periphery of the nut member (64) An adjustment screw (65) having a male screw (69) that engages with the female screw (68) on the outer periphery, and a return spring that urges the adjustment screw (65) in a direction protruding downward from the nut member (64) ( 66), and the adjust screw (65) presses the valve stem (55) of the valve gear with the adjust screw (65) until the return spring (66) is restored to its natural length. 65), the male screw (69) and the female screw (68) are screw-engaged with a length of at least one pitch. Lash adjuster to.   The lash adjuster according to any one of claims 1 to 3, wherein the male screw (18) and the female screw (17) are multi-threaded screws.   The male screw (18) and the female screw (17) are configured such that the flank angle of the pressure side flank (19) that receives pressure when the force in the direction of pushing the adjusting screw (14) into the nut member (13) is applied is the play side. The lash adjuster according to any one of claims 1 to 4, wherein the lash adjuster is formed larger than a flank angle of the flank (20).   The lash adjuster according to any one of claims 1 to 5, wherein the return spring (15) is a coil spring.

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