Lash adjuster

Abstract

The object is to prevent the adjusting screw from being pushed in while rotating when a load is applied to the adjusting screw that tends to push in the adjusting screw. In a lash adjuster comprising a cylindrical housing 12 inserted in a receiving hole 11 formed in the top surface of a cylinder head 2 and having an internal thread 13 on the inner periphery thereof, an adjusting screw 15 having an external thread 14 on the outer periphery thereof and in threaded engagement with the internal thread 13 on the housing 12 , and a return spring 17 biasing the adjusting screw 15 in a direction to protrude upwardly from the housing 12 , the adjusting screw 15 having a protruding end 19 protruding from the housing 12 and supporting an arm 7 , the surface of the protruding end 19 of the adjusting screw 15 is made of a material that does not react with oil additives of oil containing organic molybdenum.

1 . A lash adjuster comprising a cylindrical housing ( 12 ) adapted to be inserted in a receiving hole ( 11 ) formed in a top surface of a cylinder head ( 2 ) and having an internal thread ( 13 ) on an inner periphery thereof, an adjusting screw ( 15 ) having an external thread ( 14 ) on an outer periphery thereof and in threaded engagement with the internal thread ( 13 ) on the housing ( 12 ), and a return spring ( 17 ) biasing the adjusting screw ( 15 ) in a direction to protrude upwardly from the housing ( 12 ), said adjusting screw ( 15 ) having a protruding end ( 19 ) protruding from the housing ( 12 ) and adapted to support an arm ( 7 ) of a valve gear,
 characterized in that the surface of the protruding end ( 19 ) of the adjusting screw ( 15 ) is made of a material that does not react with oil additives of oil containing organic molybdenum.   
     
     
         2 . The lash adjuster of  claim 1  wherein the adjusting screw ( 15 ) is made of a non-ferrous metal that does not react with oil additives of oil containing organic molybdenum. 
     
     
         3 . The lash adjuster of  claim 1  wherein the adjusting screw ( 15 ) is made of iron, and wherein the protruding end ( 19 ) of the adjusting screw ( 15 ) is coated with a nonreactive film ( 22 ) selected from ceramic film, carbon film, oxide film, diamond-like carbon film, titanium nitride film and chromium nitride film. 
     
     
         4 . The lash adjuster of  claim 1  wherein the adjusting screw ( 15 ) is made of iron, and wherein a nitride compound layer is formed on the protruding end ( 19 ) of the adjusting screw ( 15 ). 
     
     
         5 . The lash adjuster of  claim 1  wherein the adjusting screw ( 15 ) is made of iron, and wherein nickel-phosphorus plating is provided on the protruding end ( 19 ) of the adjusting screw ( 15 ). 
     
     
         6 . The lash adjuster of  claim 5  wherein the nickel-phosphorus plating is dispersion plating comprising a plating layer in which hard particulates are dispersed. 
     
     
         7 . The lash adjuster of  claim 5  wherein the nickel-phosphorus plating is dispersion plating comprising a plating layer in which PTFE is dispersed. 
     
     
         8 . A lash adjuster comprising a cylindrical housing ( 12 ) adapted to be inserted in a receiving hole ( 11 ) formed in a top surface of a cylinder head ( 2 ) and having an internal thread ( 13 ) on an inner periphery thereof, an adjusting screw ( 15 ) having an external thread ( 14 ) on an outer periphery thereof and in threaded engagement with the internal thread ( 13 ) on the housing ( 12 ), a return spring ( 17 ) biasing the adjusting screw ( 15 ) in a direction to protrude upwardly from the housing ( 12 ), and an arm ( 7 ) having a recess ( 20 ) in which a protruding end ( 19 ) of the adjusting screw ( 15 ) protruding from the housing ( 12 ) is received, whereby the arm ( 7 ) is supported by the protruding end ( 19 ) of the adjusting screw ( 15 ),
 characterized in that the arm ( 7 ) is made of iron and the inner surface of the recess ( 20 ) of the arm ( 7 ) is made of a material that does not react with oil additives of oil containing organic molybdenum.   
     
     
         9 . The lash adjuster of  claim 8  wherein the recess ( 20 ) of the arm ( 7 ) is coated with a nonreactive film ( 22 ) selected from ceramic film, carbon film, oxide film, diamond-like carbon film, titanium nitride film and chromium nitride film. 
     
     
         10 . The lash adjuster of  claim 8  wherein a nitride compound layer is formed on the inner surface of the recess ( 20 ) of the arm ( 7 ). 
     
     
         11 . The lash adjuster of  claim 8  wherein nickel-phosphorus plating is provided on the recess ( 20 ) of the arm ( 7 ). 
     
     
         12 . The lash adjuster of  claim 11  wherein the nickel-phosphorus plating is dispersion plating comprising a plating layer in which hard particulates are dispersed. 
     
     
         13 . The lash adjuster of  claim 11  wherein the nickel-phosphorus plating is dispersion plating comprising a plating layer in which PTFE is dispersed. 
     
     
         14 . A lash adjuster comprising a cylindrical housing ( 12 ) adapted to be inserted in a receiving hole ( 11 ) formed in a top surface of a cylinder head ( 2 ) and having an internal thread ( 13 ) on an inner periphery thereof, an adjusting screw ( 15 ) having an external thread ( 14 ) on an outer periphery thereof and in threaded engagement with the internal thread ( 13 ) on the housing ( 12 ), a return spring ( 17 ) biasing the adjusting screw ( 15 ) in a direction to protrude upwardly from the housing ( 12 ), and an arm ( 7 ) having a recess ( 62 ) in which a protruding end ( 61 ) of the adjusting screw ( 15 ) protruding from the housing ( 12 ) is received, wherein the protruding end ( 61 ) of the adjusting screw ( 15 ) is hemispherical in shape and is in contact with the recess ( 62 ) of the arm ( 7 ) at its radially outer portion,
 characterized in that as taken along a plane containing an axis (L) of the adjusting screw ( 15 ), the recess ( 62 ) of the arm ( 7 ) has a section whose radius of curvature (A 2 ) is larger than the radius of curvature (A 1 ) of the protruding end ( 61 ) of the adjusting screw ( 15 ), whereby the protruding end ( 61 ) possesses the wedging effect.   
     
     
         15 . The lash adjuster of  claim 14  wherein the recess ( 62 ) of the arm ( 7 ) has an arcuate section as taken along a plane containing the axis (L) of the adjusting screw ( 15 ), and has centers of arc that are offset from the axis (L) of the adjusting screw ( 15 ) such that a radius of arc (A 2 ) of the recess ( 62 ) intersects the axis (L) of the adjusting screw ( 15 ), and wherein the protruding end ( 61 ) of the adjusting screw ( 15 ) has an arcuate section having a center located on the axis (L) of the adjusting screw ( 15 ), as taken along a plane containing the axis (L) of the adjusting screw ( 15 ). 
     
     
         16 . The lash adjuster of  claim 14  wherein a cutout ( 63 ) is formed in the inner surface of the recess ( 62 ) of the arm ( 7 ) at its central portion. 
     
     
         17 . The lash adjuster of  claim 14  wherein the recess ( 72 ) of the arm ( 7 ) has an arcuate section having a center located on the axis (L) of the adjusting screw ( 15 ), as taken along a plane containing the axis (L) of the adjusting screw ( 15 ), and wherein the protruding end ( 71 ) of the adjusting screw ( 15 ) has an arcuate section as taken along a plane containing the axis (L) of the adjusting screw ( 15 ), and has centers of arc that are offset from the axis (L) of the adjusting screw such that a radius of arc (B 1 ) of the protruding end ( 71 ) is separate from the axis (L) of the adjusting screw ( 15 ). 
     
     
         18 . The lash adjuster of  claim 17  wherein a cutout ( 63 ) is formed in the inner surface of the recess ( 72 ) of the arm ( 7 ) at its central portion. 
     
     
         19 . The lash adjuster of  claim 14  wherein the recess ( 82 ) of the arm ( 7 ) has an arcuate section as taken along a plane containing the axis (L) of the adjusting screw ( 15 ), and has centers of arc that are offset from the axis (L) of the adjusting screw ( 15 ) such that a radius of arc (C 2 ) of the recess ( 82 ) intersects the axis (L) of the adjusting screw ( 15 ), and wherein the protruding end ( 81 ) of the adjusting screw ( 15 ) has an arcuate section as taken along a plane containing the axis (L) of the adjusting screw ( 15 ), and has centers of arc that are offset from the axis (L) of the adjusting screw such that a radius of arc (C 1 ) of the protruding end ( 81 ) is separate from the axis (L) of the adjusting screw ( 15 ). 
     
     
         20 . The lash adjuster of  claim 19  wherein a cutout ( 63 ) is formed in the inner surface of the recess ( 82 ) of the arm ( 7 ) at its central portion. 
     
     
         21 . A lash adjuster comprising a cylindrical housing ( 12 ) adapted to be inserted in a receiving hole ( 11 ) formed in a top surface of a cylinder head ( 2 ) and having an internal thread ( 13 ) on an inner periphery thereof, an adjusting screw ( 15 ) having an external thread ( 14 ) on an outer periphery thereof and in threaded engagement with the internal thread ( 13 ) on the housing ( 12 ), and a return spring ( 17 ) biasing the adjusting screw ( 15 ) in a direction to protrude upwardly from the housing ( 12 ), said adjusting screw ( 15 ) having a hemispherical protruding end ( 91 ) protruding from the housing ( 12 ) and adapted to pivotally support an arm ( 7 ) of a valve gear,
 characterized in that a recessed surface ( 93 ) or a flat surface is formed on the protruding end ( 91 ) of the adjusting screw ( 15 ) at its central portion, the recessed surface ( 93 ) or the flat surface having a diameter (D 1 ) which is half or more than half the diameter (D 2 ) of the protruding end ( 91 ) of the adjusting screw ( 15 ).   
     
     
         22 - 24 . (canceled) 
     
     
         25 . A lash adjuster of  claim 21  wherein the adjusting screw comprises a pivot member ( 15 A) axially slidably inserted in the housing ( 12 ), an externally threaded member ( 15 B) supporting an end of the pivot member ( 15 A) inserted in the housing ( 12 ) and having said external thread ( 14 ) on its outer periphery, and an elastic member ( 15 C) disposed between the pivot member ( 15 A) and the externally threaded member ( 15 B). 
     
     
         26 . A lash adjuster of  claim 1  wherein the adjusting screw comprises a pivot member ( 15 A) axially slidably inserted in the housing ( 12 ), an externally threaded member ( 15 B) supporting an end of the pivot member ( 15 A) inserted in the housing ( 12 ) and having said external thread ( 14 ) on its outer periphery, and an elastic member ( 15 C) disposed between the pivot member ( 15 A) and the externally threaded member ( 15 B). 
     
     
         27 . A lash adjuster of  claim 8  wherein the adjusting screw comprises a pivot member ( 15 A) axially slidably inserted in the housing ( 12 ), an externally threaded member ( 15 B) supporting an end of the pivot member ( 15 A) inserted in the housing ( 12 ) and having said external thread ( 14 ) on its outer periphery, and an elastic member ( 15 C) disposed between the pivot member ( 15 A) and the externally threaded member ( 15 B). 
     
     
         28 . A lash adjuster of  claim 14  wherein the adjusting screw comprises a pivot member ( 15 A) axially slidably inserted in the housing ( 12 ), an externally threaded member ( 15 B) supporting an end of the pivot member ( 15 A) inserted in the housing ( 12 ) and having said external thread ( 14 ) on its outer periphery, and an elastic member ( 15 C) disposed between the pivot member ( 15 A) and the externally threaded member ( 15 B).