Lash adjuster

Abstract

A lash adjuster is provided of which an adjusting screw can be repeatedly fixed in position. The lash adjuster includes a nut member 14 having an internal thread 15 on an inner periphery thereof, an adjusting screw 17 having a external thread 16 on the outer periphery thereof which is in threaded engagement with the internal thread 15, and a return spring 19 biasing the adjusting screw 17 in the direction to protrude from the nut member 14, wherein the lash adjuster further includes an initial setting member 25 detachably disposed between the adjusting screw 17 and the nut member 14, and wherein the adjusting screw 17 is fixed to the nut member 14 due to frictional forces between the initial setting member 25 and the adjusting screw 17 and between the initial setting member 25 and the nut member 14.

1 . A lash adjuster comprising a nut member ( 14 ) having an internal thread ( 15 ) on an inner periphery thereof, an adjusting screw ( 17 ) having a external thread ( 16 ) on an outer periphery thereof which is in threaded engagement with the internal thread ( 15 ), and a return spring ( 19 ) biasing the adjusting screw ( 17 ) in a direction to protrude from the nut member ( 14 ),
 characterized in that the lash adjuster further comprises an initial setting member ( 25 ,  75 ) detachably disposed between the adjusting screw ( 17 ) and the nut member ( 14 ), wherein the adjusting screw ( 17 ) is fixed to the nut member ( 14 ) due to frictional forces between the initial setting member ( 25 ,  75 ) and the adjusting screw ( 17 ) and between the initial setting member ( 25 ,  75 ) and the nut member ( 14 ).   
     
     
         2 . The lash adjuster of  claim 1  wherein said adjusting screw ( 17 ) has a head ( 23 ) protruding from the nut member ( 14 ) and having a larger outer diameter than an inner diameter of the nut member ( 14 ), and wherein said initial setting member ( 25 ) comprises a pair of arm portions ( 26 ) disposed between the head ( 23 ) of the adjusting screw ( 17 ) and the nut member ( 14 ), and a operating tab portion ( 27 ) connecting together ends of the respective arm portions ( 26 ), said arm portions ( 26 ) being elastically compressible between the head ( 23 ) of the adjusting screw ( 17 ) and the nut member ( 14 ). 
     
     
         3 . The lash adjuster of  claim 2  wherein said initial setting member ( 25 ) is formed by bending a metal wire, and wherein said arm portions ( 26 ) are formed by bending the metal wire into a corrugated shape and have elasticity. 
     
     
         4 . The lash adjuster of  claim 2  wherein said initial setting member ( 28 ) is formed by pressing a metal sheet, and wherein said arm portions ( 29 ) are formed by bending the metal sheet into a corrugated shape and have elasticity. 
     
     
         5 . The lash adjuster of  claim 2  wherein said initial setting member ( 32 ) is formed by injection-molding an elastic resin. 
     
     
         6 . The lash adjuster of  claim 4  wherein the operating tab portion ( 30 ) is formed with a jig-inserting hole ( 31 ) for inserting a jig. 
     
     
         7 . The lash adjuster of  claim 1  wherein a cutout ( 73 ) is formed in at least one of the outer periphery of the adjusting screw ( 17 ) and the inner periphery of the nut member ( 14 ) that defines an insertion opening ( 74 ), and wherein the initial setting member ( 75 ) is inserted in the insertion opening ( 74 ) in an elastically compressed state. 
     
     
         8 . The lash adjuster of  claim 7  wherein the adjusting screw ( 17 ) comprises a pivot member ( 17 A) axially slidably inserted in the nut member ( 14 ), an externally threaded member ( 17 B) supporting an end of the pivot member ( 17 A) inserted in the nut member ( 14 ) and having said external thread ( 16 ) on an outer periphery thereof, and an elastic member ( 17 C) disposed between the pivot member ( 17 A) and the externally threaded member ( 17 B), and wherein said cut-out ( 102 ) is formed on an outer periphery of the pivot member ( 17 A). 
     
     
         9 . The lash adjuster of  claim 7  wherein said cut-out is a D-cut portion ( 102 ) formed on the outer periphery of the adjusting screw ( 57 ). 
     
     
         10 . The lash adjuster of  claim 7  wherein said cut-out comprises two chamfers formed on the outer periphery of the adjusting screw ( 17 ). 
     
     
         11 . The lash adjuster of  claim 7  wherein there are a plurality of said cut-outs ( 73 ), each cut-out ( 73 ) separating the external thread ( 16 ) on the outer periphery of the adjusting screw ( 17 ) into a plurality of sections, and wherein said plurality of cut-outs ( 73 ) being circumferentially equidistantly spaced from each other. 
     
     
         12 . The lash adjuster of  claim 7  wherein the initial setting member ( 75 ) further comprises a pull-out portion ( 77 ) which can be engaged by a finger, whereby the initial setting member ( 75 ) can be pulled out of the insertion opening ( 74 ) with the finger. 
     
     
         13 . The lash adjuster of  claim 7  wherein said initial setting member ( 75 ) is made of rubber or resin. 
     
     
         14 . The lash adjuster of  claim 1  wherein the nut member ( 14 ) is inserted in a mounting hole ( 13 ) formed in a top surface of a cylinder head ( 2 ), and wherein the adjusting screw ( 17 ) pivotally supports an arm ( 7 ) of a valve gear. 
     
     
         15 . The lash adjuster of  claim 1  wherein the nut member ( 54 ) is inserted in a mounting hole ( 53 ) formed in a bottom surface of an arm ( 47 ) that pivots as a cam ( 46 ) rotates, and wherein the adjusting screw ( 57 ) presses a valve stem of a valve gear. 
     
     
         16 . The lash adjuster of  claim 5  wherein the operating tab portion ( 30 ) is formed with a jig-inserting hole ( 31 ) for inserting a jig. 
     
     
         17 . The lash adjuster of  claim 8  wherein said cut-out is a D-cut portion ( 102 ) formed on the outer periphery of the adjusting screw ( 57 ). 
     
     
         18 . The lash adjuster of  claim 8  wherein said cut-out comprises two chamfers formed on the outer periphery of the adjusting screw ( 17 ). 
     
     
         19 . The lash adjuster of  claim 8  wherein there are a plurality of said cut-outs ( 73 ), each cut-out ( 73 ) separating the external thread ( 16 ) on the outer periphery of the adjusting screw ( 17 ) into a plurality of sections, and wherein said plurality of cut-outs ( 73 ) being circumferentially equidistantly spaced from each other.