JP2009216031A - Lash adjuster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lash adjuster capable of preventing a concentration of stress in the apex of a thread when the slant moment is applied. <P>SOLUTION: This lash adjuster is constituted by having an adjuster body 13 slidably inserted into a housing hole 12 formed at the top surface of a cylinder head 2 and a bolt member 14 supported at one end thereof in the bottom of the housing hole 12, forming the adjuster body 13 into a bottomed cylindrical shape formed at an insertion end thereof into the housing hole 12, screwing a male screw 16 formed at the outer periphery of the bolt member 14 into a female screw 15 formed at the inner periphery of the adjuster body 13 for engagement, and energizing the adjuster body 13 in a direction protruding from the housing hole 12 with a return spring 20 incorporated between the bolt member 14 and the adjuster body 13, and supporting an arm 7 of a valve gear freely to swing with a protrusion end 23 of the adjuster body 13 protruding from the housing hole 12. <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 A thing (a rocker arm type valve gear) is known.

  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).

  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 2).

  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 JP 2006-132426 A

  By the way, the lash adjuster of the swing arm type valve device or the rocker arm type valve device falls over the adjustment screw due to a deviation between the moving direction of the arm and the moving direction of the valve stem when the valve stem is pushed down by the arm. Moment acts.

  However, each lash adjuster maintains the position of the adjusting screw by the contact between the adjusting screw male screw and the nut member female screw, so that when a tilting moment acts on the adjusting screw, stress concentration occurs at the top of the screw thread. Prone to occur.

  Therefore, in each of the above lash adjusters, the male screw and the female screw are likely to wear along the top of the thread, and the friction coefficient between the pressure side flank of the male screw and the female screw may be reduced due to the wear. In this case, the amount of pushing of the adjusting screw when the load in the pushing direction by the cam is applied increases, so that the adjusting screw moves in the pushing direction each time the cam rotates, and as a result, the valve is seated impactively. There is a risk that abnormal noise may occur, and fuel consumption may decrease due to a decrease in valve lift.

  The problem to be solved by the present invention is to provide a lash adjuster in which stress concentration is unlikely to occur at the top of a thread when a falling moment is applied.

  In order to solve the above problems, in a swing arm type valve operating apparatus, an adjustment body that is slidably inserted into a receiving hole opened on the upper surface of a cylinder head, and a bolt whose one end is supported at the bottom of the receiving hole The adjustment body has a bottomed cylindrical shape with an opening at the insertion hole into the receiving hole, and a male screw formed on the outer periphery of the bolt member is screwed to a female screw formed on the inner periphery of the adjustment body. The male screw and the female screw have a sawtooth shape with a flank angle of the pressure side flank that receives pressure when a load is applied in a direction in which the adjustment body is pushed into the accommodation hole, and is larger than the flank angle of the play side flank. The return body is formed between the bolt member and the adjustment body, and the adjustment body is attached in a direction protruding from the receiving hole. And, employing the configuration so as to support the arm of the valve gear swingably end protruding from the accommodation hole of the adjusting body to the lash adjuster.

  In addition, the above-described problem adopts a configuration in which the adjustment body is slidably inserted into a bottomed cylindrical case fitted into the accommodation hole instead of slidably inserting the adjustment body into the accommodation hole. Even it can be solved.

  That is, it has a bottomed cylindrical case that is fitted into a receiving hole opened on the upper surface of the cylinder head, an adjustment body that is slidably inserted into the case, and a bolt member that is supported at one end by the bottom of the case. The adjustment body is in the shape of a bottomed cylinder with an insertion end into the case opened, and a male screw formed on the outer periphery of the bolt member is thread-engaged with a female screw formed on the inner periphery of the adjustment body, The male screw and the female screw are formed so that the flank angle of the pressure side flank that receives pressure when a load in the direction of pushing the adjust body into the case is applied is formed in a sawtooth shape larger than the flank angle of the play side flank. A return spring incorporated between the member and the adjustment body urges the adjustment body in a direction protruding from the case, and It can be an arm structure which is adapted to swingably support of the valve gear with its end protruding from the case of Sutobodi adopted the lash adjuster resolve.

  Similarly, in the rocker arm type valve gear, the above-mentioned problem is that an adjustment body that is slidably inserted into a receiving hole opened in a lower surface of an arm that swings according to rotation of a cam, and a bottom of the receiving hole. A bolt member supported at one end thereof, and the adjustment body has a bottomed cylindrical shape whose opening end into the receiving hole opens, and an outer periphery of the bolt member is formed on a female screw formed on an inner periphery of the adjustment body. The male screw and the female screw are engaged with each other, and the male screw and the female screw have the flank angle of the pressure side flank that receives pressure when a load in the direction of pushing the adjustment body into the receiving hole is applied, and the flank of the play side flank. It is formed in a sawtooth shape larger than the corner, and the adjustment body is protruded from the receiving hole by a return spring incorporated between the bolt member and the adjustment body. That is biased in a direction, by employing the configuration which is adapted to press the valve stem of the valve gear with its end protruding from the accommodation hole of the adjusting body in the lash adjuster, can be solved.

  In addition, the above-described problem adopts a configuration in which the adjustment body is slidably inserted into a bottomed cylindrical case fitted into the accommodation hole instead of slidably inserting the adjustment body into the accommodation hole. Even it can be solved.

  That is, a bottomed cylindrical case fitted in a receiving hole opened in the lower surface of the arm that swings according to the rotation of the cam, an adjustment body slidably inserted into the case, and one end at the bottom of the case The adjustment body is formed in a bottomed cylindrical shape with an opening at the insertion end into the case, and a female screw formed on the inner periphery of the adjustment body is formed on the outer periphery of the bolt member. The male screw is engaged with the screw, and the male screw and the female screw have a larger flank angle of the pressure side flank that receives pressure when a load is applied in a direction of pushing the adjustment body into the case than the flank angle of the play side flank. A direction in which the adjustment body protrudes from the case with a return spring formed in a sawtooth shape and incorporated between the bolt member and the adjustment body Biases, can be solved by adopting the configuration which is adapted to press the valve stem of the valve gear with its end protruding from the case of the adjusting body to the lash adjuster.

Each of the lash adjusters can have the following configuration.
1) Of the pressure side flank of the male screw and the pressure side flank of the female screw, at least one pressure side flank is a matte surface having a surface roughness of Ra 0.4 or more.
2) The axial clearance between the male screw and the female screw is set in the range of 0.2 to 0.4 mm.

  The lash adjuster of the present invention having an adjustment body slidably inserted into a receiving hole opened in the upper surface of the cylinder head and a bolt member supported at one end by the bottom of the receiving hole has a tilting moment on the adjusting body. When acting, the tilting moment is received by the inner periphery of the receiving hole, so that the tilting moment is unlikely to act on the female screw of the adjustment body and the male screw of the bolt member, and stress concentration is unlikely to occur at the top of the thread. Therefore, in this lash adjuster, the male screw and the female screw are not easily worn, and the friction coefficient between the pressure side flank of the male screw and the female screw is not easily lowered.

  The present invention includes a bottomed cylindrical case that is fitted into an accommodation hole that is opened in the upper surface of the cylinder head, an adjustment body that is slidably inserted into the case, and a bolt member that is supported at one end by the bottom of the case. In the lash adjuster, when a falling moment is applied to the adjustment body, the falling moment is received by the inner circumference of the case, so the falling moment is unlikely to act on the female screw of the adjustment body and the male screw of the bolt member. Stress concentration is unlikely to occur. Therefore, this lash adjuster is less likely to wear the pressure side flank and can prevent a decrease in the friction coefficient between the pressure side flank of the male screw and the female screw. In addition, the lash adjuster can ensure durability by using a metal (such as iron) that has higher wear resistance than the material (such as aluminum alloy) of the cylinder head as the material of the case.

  Further, the present invention includes an adjustment body that is slidably inserted into a receiving hole opened in a lower surface of an arm that swings according to rotation of the cam, and a bolt member that is supported at one end by the bottom of the receiving hole. The lash adjuster receives the falling moment at the inner periphery of the receiving hole when a falling moment is applied to the adjustment body, so the falling moment is unlikely to act on the female screw of the adjustment body and the male screw of the bolt member. Stress concentration is unlikely to occur. Therefore, this lash adjuster is less likely to wear the pressure side flank and can prevent a decrease in the friction coefficient between the pressure side flank of the male screw and the female screw.

  A bottomed cylindrical case that is fitted into a receiving hole that opens in the lower surface of the arm that swings according to the rotation of the cam, an adjustment body that is slidably inserted into the case, and one end supported by the bottom of the case. The lash adjuster of the present invention having a bolt member also receives the falling moment at the inner periphery of the case when a falling moment is applied to the adjustment body, so that the falling moment acts on the female screw of the adjustment body and the male screw of the bolt member. It is difficult to cause stress concentration at the top of the thread. Therefore, this lash adjuster is less likely to wear the pressure side flank and can prevent a decrease in the friction coefficient between the pressure side flank of the male screw and the female screw. Further, this lash adjuster can ensure durability by adopting a metal (such as iron) that has higher wear resistance than the arm material (such as an aluminum alloy) as the material of the case.

  Of the pressure-side flank of the male screw and the pressure-side flank of the female screw, at least one of the pressure-side flank has a surface roughness of Ra0.4 or more is used for a long time. Even when the pressure side flank of the flank and female thread is worn, the unevenness height of the matte surface of the pressure side flank is large compared to the amount of wear, and the surface of the pressure side flank is difficult to be smooth. Therefore, it is possible to more effectively prevent a reduction in the friction coefficient between the pressure side flank of the male screw and the female screw.

  In addition, in the case where the axial clearance between the male screw and the female screw is set in a range of 0.2 to 0.4 mm, the engine stops at a high temperature, and then the engine cools between the constituent members of the valve gear. When a contraction difference occurs, the contraction difference can be absorbed by the axial gap between the male screw and the female screw. Therefore, when the engine is restarted, there is no compression leakage due to the contraction difference between the constituent members of the valve gear.

  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 includes an adjustment body 13 that is slidably inserted into a receiving hole 12 that opens on the upper surface of the cylinder head 2, and a bolt member 14 that is supported at one end at the bottom of the receiving hole 12. And have.

  The adjustment body 13 is formed in a bottomed cylindrical shape having an insertion end into the accommodation hole 12, and a female screw 15 is formed on the inner periphery thereof. The outer periphery of the adjustment body 13 is in sliding contact with the inner periphery of the accommodation hole 12, and the adjustment body 13 is held coaxially with respect to the accommodation hole 12 by the sliding contact.

  On the other hand, on the outer periphery of the bolt member 14, a male screw 16 that engages with the female screw 15 of the adjustment body 13 is formed. Further, a flange portion 17 that fits the inner periphery of the accommodation hole 12 is formed at the insertion end of the bolt member 14 into the accommodation hole 12, and the male screw 16 is inserted into the accommodation hole 12 by the fitting of the flange portion 17. On the other hand, it is held coaxially.

  The male screw 16 and the female screw 15 have a sawtooth shape in which the flank angle of the pressure-side flank 18 that receives pressure when a load in the direction of pushing the adjustment body 13 into the receiving hole 12 is applied is larger than the flank angle of the play-side flank 19. Is formed. As the male screw 16 and the female screw 15, for example, those having a flank angle of the pressure side flank 18 of 75 ° and a flank angle of the play side flank 19 of 15 ° can be employed.

  The pressure-side flank 18 of the male screw 16 is a matte surface having a surface roughness Ra of 0.4 or more by performing shot peening. The satin can be formed by shot peening using a medium with acute-angle grains. When the bolt member 14 is subjected to heat treatment (for example, carburizing treatment or nitriding treatment), shot peening is performed before the heat treatment. Can be formed. The surface roughness Ra is based on JIS0601 (product geometric characteristic specification (GPS) -surface property: contour curve method-terminology, definition and surface property parameter).

  An axial gap t (see FIG. 3) is provided between the male screw 16 and the female screw 15, and the axial gap t is set in a range of 0.2 to 0.4 mm.

  A return spring 20 is incorporated between the adjustment body 13 and the bolt member 14. One end of the return spring 20 is supported by the bolt member 14 via the spring seat 21, and the other end presses the adjustment body 13, and the adjustment body 13 is biased in a direction protruding from the accommodation hole 12 by the pressing. is doing. In the spring seat 21, a contact surface 22 with respect to the bolt member 14 is formed in a spherical shape in order to reduce friction with the bolt member 14.

  The adjustment body 13 has a protruding end 23 from the accommodation hole 12 in a hemispherical shape, and the protruding end 23 is fitted in a recess 24 formed on the lower surface of the end of the arm 7. Here, the projecting end 23 slidably contacts the inner surface of the recess 24 of the arm 7 and supports the arm 7 so as to be swingable by the sliding.

  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 adjustment body 13, but the pressure side flank 18 of the male screw 16 is received by the pressure side flank 18 of the female screw 15, and the axial position of the adjustment body 13 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 18, 18 of the male screw 16 and the female screw 15, and the adjustment body 13 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 push-in direction is released, the adjustment body 13 moves in the protruding direction by the load in the protruding direction loaded from the return spring 20, 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 body 13 when the cam 6 rotates and the load in the pushing direction is released is larger than the amount of pushing of the adjusting body 13 when the cam crest 6a pushes down the arm 7. As a result, each time the cam 6 rotates, the adjustment body 13 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 body 13 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 body 13 when the cam 6 rotates and the load in the pushing direction is released is smaller than the amount of pushing of the adjusting body 13 when the cam crest 6a of the cam 6 pushes down the arm 7. As a result, every time the cam 6 rotates, the adjustment body 13 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.

  When the lash adjuster 1 pushes down the valve stem 5 with the arm 7, a tilting moment may act on the adjustment body 13 due to a shift between the moving direction of the arm 7 and the moving direction of the valve stem 5. Since the falling moment is received by the inner periphery of the receiving hole 12, the falling moment is unlikely to act on the female screw 15 of the adjustment body 13 and the male screw 16 of the bolt member 14, and stress concentration is unlikely to occur at the top of the screw thread. Therefore, in the lash adjuster 1, the male screw 16 and the female screw 15 are less likely to wear, and the friction coefficient between the pressure side flank 18, 18 of the male screw 16 and the female screw 15 is less likely to occur.

  Further, the lash adjuster 1 has a large uneven height of the matte surface of the pressure side flank 18 even when the pressure side flank 18 of the male screw 16 is worn due to long-term use. The surface of the pressure side flank 18 is difficult to be smooth. Therefore, the lash adjuster 1 can effectively prevent the friction coefficient between the pressure side flank 18, 18 of the male screw 16 and the female screw 15 from being lowered.

  Further, in this lash adjuster 1, since the axial clearance between the male screw 16 and the female screw 15 is 0.2 mm or more, the engine stops at a high temperature, and then the engine cools and contracts between the components of the valve gear. When a difference occurs, the contraction difference can be absorbed by the axial gap between the male screw 16 and the female screw 15. Therefore, when the engine is restarted, a gap due to a contraction difference between the constituent members of the valve operating device does not occur between the valve 4 and the valve seat 10, and compression leakage does not occur.

  The bottomed cylindrical adjustment body 13 may be integrally formed of a sintered alloy or the like, but as shown in FIG. 2, a cap member 13b is fixed to one end of a cylindrical nut member 13a having both ends opened. Forming the internal thread 15 is easy. In this case, the cap member 13b can be fixed, for example, by press fitting or welding to the nut member 13a.

  Further, the adjustment body 13 may be formed with an oil passage (not shown) through which engine oil splashed on the cylinder head 2 is introduced into the adjustment body 13.

  In this embodiment, of the pressure side flank 18 of the male screw 16 and the female screw 15, the pressure side flank 18 of the male screw 16 is a matte surface, but the pressure side flank 18 of the female screw 15 is replaced with the pressure side flank 18 of the male screw 16. It is good also as a satin with surface roughness Ra0.4 or more. Even in this case, the unevenness height of the matte surface of the pressure side flank 18 of the female screw 15 is larger than the wear amount of the pressure side flank 18 due to long-term use, and therefore the pressure side flank 18 of the male screw 16 and the female screw 15. , 18 can be effectively prevented from lowering the friction coefficient. Further, both the pressure side flank 18, 18 of the male screw 16 and the female screw 15 may be satin having a surface roughness of Ra 0.4 or more.

  FIG. 4 shows a lash adjuster 31 according to the second 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 31 includes a bottomed cylindrical case 32 that is fitted into the receiving hole 12 that opens on the upper surface of the cylinder head 2, an adjustment body 13 that is slidably inserted into the case 32, and a bottom 33 of the case 32. Is supported by the bolt member 14.

  The case 32 is formed of a metal that is more excellent in wear resistance than the material of the cylinder head 2. Here, when the material of the cylinder head 2 is an aluminum alloy, the material of the case 32 may be, for example, iron.

  The adjust body 13 is formed in a bottomed cylindrical shape with an opening end into the case 32 opened, and an internal thread 15 is formed on the inner periphery thereof. The outer periphery of the adjustment body 13 is in sliding contact with the inner periphery of the case 32, and the adjustment body 13 is held coaxially with respect to the case 32 by the sliding contact.

  On the other hand, on the outer periphery of the bolt member 14, a male screw 16 that engages with the female screw 15 of the adjustment body 13 is formed. Further, a flange portion 17 that is fitted to the inner periphery of the case 32 is formed at an insertion end of the bolt member 14 into the case 32, and the male screw 16 is coaxial with the case 32 by the fitting of the flange portion 17. Is held in.

  The male screw 16 and the female screw 15 are formed in a sawtooth shape in which the flank angle of the pressure side flank 18 that receives pressure when a load in the direction of pushing the adjustment body 13 into the case 32 is applied is larger than the flank angle of the play side flank 19. Has been.

  The adjustment body 13 is urged in a direction protruding from the case 32 by a return spring 20 incorporated between the adjustment body 13 and the bolt member 14, and the arm 7 is swingably supported by the protruding end 23 from the case 32. is doing.

  As in the first embodiment, when the lash adjuster 31 pushes down the valve stem 5 with the arm 7, a tilting moment is exerted on the adjustment body 13 due to a shift between the moving direction of the arm 7 and the moving direction of the valve stem 5. However, since the falling moment is received by the inner circumference of the case 32, the falling moment is unlikely to act on the female screw 15 of the adjustment body 13 and the male screw 16 of the bolt member 14, and stress concentration is concentrated on the top of the thread. Hard to occur. Therefore, in the lash adjuster 31, the pressure side flank 18 of the male screw 16 and the female screw 15 is not easily worn, and the friction coefficient between the pressure side flank 18, 18 of the male screw 16 and the female screw 15 does not easily decrease.

  In addition, the lash adjuster 31 supports the outer periphery of the adjustment body 13 in a slidable manner by a case 32 made of a metal having higher wear resistance than the material of the cylinder head 2. It is more durable than a lash adjuster (for example, the lash adjuster 1 of the first embodiment) that slidably supports the outer periphery of the adjustment body 13 and can exhibit stable performance over a long period of time.

  FIG. 5 shows a valve gear incorporating a lash adjuster 41 according to a third embodiment of the present invention. This valve operating apparatus has a valve 44 provided at an intake port 43 of an engine cylinder head 42, a valve stem 45 connected to the valve 44, and an arm 47 that swings in response to rotation of a cam 46. . The valve stem 45 extends upward from the valve 44, and a spring retainer 48 is fixed to the upper portion of the valve stem 45. The spring retainer 48 is biased upward by a valve spring 49, and the valve 44 is seated on the valve seat 50 by the biasing force.

  The center of the arm 47 is supported by a fulcrum shaft 51 so as to be swingable. A roller 52 that comes into contact with the cam 46 is attached to one end of the arm 47 so that the arm 47 swings according to the rotation of the cam 46. A lash adjuster 41 is incorporated in the other end of the arm 47.

  As shown in FIG. 6, the lash adjuster 41 includes an adjustment body 54 that is slidably inserted into a receiving hole 53 that opens on the lower surface of the arm 47, and a bolt member 55 that is supported at one end at the bottom of the receiving hole 53. Have

  The adjustment body 54 is formed in a bottomed cylindrical shape whose opening end into the accommodation hole 53 is open, and a female screw 56 is formed on the inner periphery thereof. The outer periphery of the adjustment body 54 is in sliding contact with the inner periphery of the accommodation hole 53, and the adjustment body 54 is held coaxially with respect to the accommodation hole 53 by the sliding contact.

  On the other hand, a male screw 57 is formed on the outer periphery of the bolt member 55 to engage with the female screw 56 of the adjustment body 54. Further, a flange portion 58 that fits the inner periphery of the accommodation hole 53 is formed at the insertion end of the bolt member 55 into the accommodation hole 53, and the male screw 57 is inserted into the accommodation hole 53 by the fitting of the flange portion 58. On the other hand, it is held coaxially.

  The male screw 57 and the female screw 56 have a sawtooth shape in which the flank angle of the pressure side flank 59 that receives pressure when a load in the direction of pushing the adjustment body 54 into the receiving hole 53 is applied is larger than the flank angle of the play side flank 60. Is formed.

  The pressure-side flank 59 of the male screw 57 is a matte surface having a surface roughness of Ra 0.4 or more by performing shot peening. An axial gap is provided between the male screw 57 and the female screw 56, and the axial gap is set in a range of 0.2 to 0.4 mm.

  A return spring 61 is incorporated between the adjustment body 54 and the bolt member 55. One end of the return spring 61 is supported by the bolt member 55 via the spring seat 62, and the other end presses the adjustment body 54, and the adjustment body 54 is biased in a direction protruding from the accommodation hole 53 by the pressing. is doing. The protruding end of the adjustment body 54 from the accommodation hole 53 presses the upper end of the valve stem 45.

  As in the first embodiment, the lash adjuster 41 is configured such that when the cam peak portion 46a of the cam 46 pushes up the end of the arm 47 and a load in the pushing direction is applied to the adjustment body 54, the pressure side flank of the male screw 57 is applied. 59 is received by the pressure side flank 59 of the female screw 56, and the axial position of the adjustment body 54 is fixed. Strictly, at this time, slight slip occurs between the pressure side flank 59, 59 of the male screw 57 and the female screw 56, and the adjustment body 54 moves in the pushing direction by the slip, but the cam 46 further rotates to push in the pushing direction. When the load is released, the adjustment body 54 moves in the protruding direction by the load in the protruding direction loaded from the return spring 61 and returns to the original position.

  When the lash adjuster 41 pushes down the valve stem 45 with the arm 47, a tilting moment may act on the adjustment body 54 due to a shift between the moving direction of the arm 47 and the moving direction of the valve stem 45. Since the falling moment is received by the inner periphery of the receiving hole 53, the falling moment is unlikely to act on the female screw 56 of the adjustment body 54 and the male screw 57 of the bolt member 55, and stress concentration is unlikely to occur at the top of the screw thread. Therefore, in the lash adjuster 41, the pressure-side flank 59 of the male screw 57 and the female screw 56 is not easily worn, and the friction coefficient between the pressure-side flanks 59 and 59 of the male screw 57 and the female screw 56 is hardly reduced.

  In addition, the lash adjuster 41 has a large uneven height on the matte surface of the pressure side flank 59 even when the pressure side flank 59 of the male screw 57 is worn due to long-term use. The surface of the pressure side flank 59 is difficult to be smooth. Therefore, the lash adjuster 41 can effectively prevent the friction coefficient between the pressure side flanks 59 and 59 of the male screw 57 and the female screw 56 from being lowered.

  Further, the lash adjuster 41 has an axial clearance between the male screw 57 and the female screw 56 of 0.2 mm or more, so that the engine stops at a high temperature, and then the engine cools and contracts between the components of the valve gear. When the difference occurs, the contraction difference can be absorbed by the axial gap between the male screw 57 and the female screw 56. Therefore, when the engine is restarted, a gap due to a contraction difference between the constituent members of the valve operating device does not occur between the valve 44 and the valve seat 50, and compression leakage does not occur.

  As in the first embodiment, the bottomed cylindrical adjustment body 54 may be integrally formed of a sintered alloy or the like. However, as shown in FIG. 6, at one end of a cylindrical nut member 54a having both ends opened. When the cap member 54b is fixed and formed, the internal thread 56 can be easily formed. In this case, the cap member 54b can be fixed, for example, by press fitting or welding to the nut member 54a.

  In this embodiment, of the pressure side flank 59 of the male screw 57 and the female screw 56, the pressure side flank 59 of the male screw 57 is a matte surface, but the pressure side flank 59 of the female screw 56 is replaced with the pressure side flank 59 of the male screw 57. It is good also as a satin with surface roughness Ra0.4 or more. Further, both the pressure side flank 59, 59 of the male screw 57 and the female screw 56 may be satin having a surface roughness of Ra 0.4 or more.

  FIG. 7 shows a lash adjuster 71 according to the fourth 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 71 has one end at a bottomed cylindrical case 72 that is fitted into a receiving hole 53 that opens on the lower surface of the arm 47, an adjustment body 54 that is slidably inserted into the case 72, and a bottom 73 of the case 72. And a supported bolt member 55.

  The case 72 is made of a metal that is more excellent in wear resistance than the material of the arm 47. Here, when the material of the arm 47 is an aluminum alloy, the material of the case 72 may be, for example, iron.

  The adjust body 54 is formed in a bottomed cylindrical shape with an opening end into the case 72 opened, and an internal thread 56 is formed on the inner periphery thereof. Further, the outer periphery of the adjustment body 54 is in sliding contact with the inner periphery of the case 72, and the adjustment body 54 is held coaxially with respect to the case 72 by the sliding contact.

  On the other hand, a male screw 57 is formed on the outer periphery of the bolt member 55 to engage with the female screw 56 of the adjustment body 54. Further, a flange portion 58 that fits the inner periphery of the case 72 is formed at the insertion end of the bolt member 55 into the case 72, and the male screw 57 is coaxial with the case 72 by the fitting of the flange portion 58. Is held in.

  The male screw 57 and the female screw 56 are formed in a sawtooth shape in which the flank angle of the pressure side flank 59 that receives pressure when a load in the direction of pushing the adjustment body 54 into the case 72 is applied is larger than the flank angle of the play side flank 60. Has been.

  The adjustment body 54 is urged in a direction protruding from the case 72 by a return spring 61 incorporated between the adjustment body 54 and the bolt member 55, and presses the upper end of the valve stem 45 with the protruding end from the case 72. Yes.

  When the lash adjuster 71 pushes down the valve stem 45 with the arm 47, there is a case where a fall moment acts on the adjustment body 54 due to a deviation between the moving direction of the arm 47 and the moving direction of the valve stem 45. Since the falling moment is received by the inner periphery of the case 72, the falling moment is unlikely to act on the female screw 56 of the adjustment body 54 and the male screw 57 of the bolt member 55, and stress concentration is unlikely to occur at the top of the screw thread. Therefore, in the lash adjuster 71, the pressure side flank 59 of the male screw 57 and the female screw 56 is not easily worn, and the friction coefficient between the pressure side flank 59, 59 of the male screw 57 and the female screw 56 is not easily reduced.

  In addition, the lash adjuster 71 supports the outer periphery of the adjustment body 54 in a slidable manner by a case 72 made of a metal having a higher wear resistance than the material of the arm 47, so that the adjustment is performed on the inner periphery of the accommodation hole 53. The lash adjuster that slidably supports the outer periphery of the body 54 (for example, the lash adjuster 41 of the third embodiment) is superior in durability and can exhibit stable performance over a long period of time.

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. Enlarged cross-sectional view of the male and female threads in FIG. The expanded sectional view which shows the lash adjuster of 2nd Embodiment of this invention 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. The expanded sectional view which shows the lash adjuster of 4th Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 2 Cylinder head 7 Arm 12 Accommodating hole 13 Adjustment body 14 Bolt member 15 Female screw 16 Male screw 18 Pressure side flank 19 Play side flank 20 Return spring 23 Protruding end 31 Rush adjuster 32 Case 33 Bottom 41 Rush adjuster 45 Valve stem 46 Cam 47 Arm 53 Receiving hole 54 Adjust body 55 Bolt member 56 Female screw 57 Male screw 59 Pressure side flank 60 Play side flank 61 Return spring 71 Rush adjuster 72 Case 73 Bottom t Axial clearance

Claims (6)

  An adjustment body (13) slidably inserted into a receiving hole (12) opened in the upper surface of the cylinder head (2), and a bolt member (14) supported at one end by the bottom of the receiving hole (12) The adjustment body (13) has a bottomed cylindrical shape with the insertion end into the receiving hole (12) opened, and the bolt is attached to the female screw (15) formed on the inner periphery of the adjustment body (13). The male screw (16) formed on the outer periphery of the member (14) is screw-engaged, and the male screw (16) and the female screw (15) are loaded in a direction to push the adjustment body (13) into the accommodation hole (12). The flank angle of the pressure side flank (18) that receives pressure when a load is applied is formed in a sawtooth shape larger than the flank angle of the play side flank (19), and the bolt member (14) and the adjustment body (13 The adjustment body (13) is urged in a direction protruding from the accommodation hole (12) by a return spring (20) incorporated between the adjustment body (13) and the protruding end of the adjustment body (13) from the accommodation hole (12). A lash adjuster configured to support the arm (7) of the valve gear so as to be swingable in (23).   A bottomed cylindrical case (32) fitted in a receiving hole (12) opened in the upper surface of the cylinder head (2), an adjustment body (13) slidably inserted in the case (32), and the case A bolt member (14) supported at one end by a bottom (33) of (32), and the adjustment body (13) is formed in a bottomed cylindrical shape having an opening end into the case (32), A male screw (16) formed on the outer periphery of the bolt member (14) is screw-engaged with a female screw (15) formed on the inner periphery of the adjustment body (13), and the male screw (16) and the female screw (15) are engaged. The flank angle of the pressure-side flank (18) that receives pressure when a load in the direction of pushing the adjust body (13) into the case (32) is applied is larger than the flank angle of the play-side flank (19) A return spring (20) formed in a tooth shape and incorporated between the bolt member (14) and the adjustment body (13) urges the adjustment body (13) in a direction protruding from the case (32). A lash adjuster in which the arm (7) of the valve gear is swingably supported by the protruding end (23) of the adjustment body (13) from the case (32).   An adjustment body (54) slidably inserted into a receiving hole (53) opened in the lower surface of an arm (47) that swings in response to rotation of the cam (46), and a bottom of the receiving hole (53) A bolt member (55) supported at one end, and the adjustment body (54) has a bottomed cylindrical shape having an insertion end into the accommodation hole (53), and an inner periphery of the adjustment body (54) A male screw (57) formed on the outer periphery of the bolt member (55) is screw-engaged with the female screw (56) formed on the inner screw (56), and the male screw (57) and the female screw (56) connect the adjustment body (54). The flank angle of the pressure flank (59) that receives pressure when a load in the direction of pushing into the housing hole (53) is applied is formed in a sawtooth shape larger than the flank angle of the play flank (60), Bolt member (55) A return spring (61) assembled with the adjustment body (54) urges the adjustment body (54) in a direction protruding from the accommodation hole (53), and the accommodation hole ( 53) A lash adjuster configured to press the valve stem (45) of the valve operating device at the protruding end from 53).   A bottomed cylindrical case (72) fitted in a receiving hole (53) opened in the lower surface of the arm (47) that swings according to the rotation of the cam (46), and slidable in the case (72) It has an inserted adjustment body (54) and a bolt member (55) supported at one end by the bottom (73) of the case (72), and the adjustment body (54) is inserted into the case (72). A bottomed cylindrical shape having an open end, and a male screw (57) formed on the outer periphery of the bolt member (55) is screw-engaged with a female screw (56) formed on the inner periphery of the adjustment body (54), The male screw (57) and the female screw (56) allow the flank angle of the pressure-side flank (59), which receives pressure when a load in the direction of pushing the adjustment body (54) into the case (72) is applied. Side flank (6 ) Of the adjustment body (54) from the case (72) by a return spring (61) formed in a sawtooth shape larger than the flank angle of) and assembled between the bolt member (55) and the adjustment body (54). A lash adjuster that is urged in the protruding direction and presses the valve stem (45) of the valve gear with the protruding end of the adjustment body (54) from the case (72).   Of the pressure side flank (18) of the male screw (16) and the pressure side flank (18) of the female screw (15), at least one pressure side flank (18) The lash adjuster according to any one of claims 1 to 4.   The lash adjuster according to any one of claims 1 to 5, wherein an axial clearance (t) between the male screw (16) and the female screw (15) is set in a range of 0.2 to 0.4 mm.

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