US20110017161A1 - Lash adjuster - Google Patents

Lash adjuster Download PDF

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Publication number
US20110017161A1
US20110017161A1 US12/922,695 US92269509A US2011017161A1 US 20110017161 A1 US20110017161 A1 US 20110017161A1 US 92269509 A US92269509 A US 92269509A US 2011017161 A1 US2011017161 A1 US 2011017161A1
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US
United States
Prior art keywords
adjusting screw
lash adjuster
nut member
initial setting
cut
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US12/922,695
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English (en)
Inventor
Makoto Yasui
Eiji Maeno
Katsuhisa Yamaguchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTN Corp
Original Assignee
NTN Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2008083362A external-priority patent/JP2009236007A/ja
Priority claimed from JP2008211537A external-priority patent/JP2010048124A/ja
Application filed by NTN Corp filed Critical NTN Corp
Assigned to NTN CORPORATION reassignment NTN CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: YASUI, MAKOTO, MAENO, EIJI, YAMAGUCHI, KATSUHISA
Publication of US20110017161A1 publication Critical patent/US20110017161A1/en
Abandoned legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/20—Adjusting or compensating clearance
    • F01L1/22—Adjusting or compensating clearance automatically, e.g. mechanically
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F01L1/181—Centre pivot rocking arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
    • F01L1/12—Transmitting gear between valve drive and valve
    • F01L1/18—Rocking arms or levers
    • F01L1/185—Overhead end-pivot rocking arms
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L2305/00—Valve arrangements comprising rollers

Definitions

  • This invention relates to a lash adjuster mounted in a valve gear for an engine.
  • Valve gears for moving valves provided at engine intake ports or exhaust ports include ones having an arm pivotable about one end thereof and adapted to be pressed down by a cam at its mid-portion, thereby pressing down a valve stem at its other end (swing arm type valve gear), and ones having an arm pivotable its mid-portion and adapted to be pushed up by a cam at one end thereof, thereby pressing down a valve stem at its other end (rocker arm type valve gear).
  • valve gears ordinarily include a lash adjuster to absorb changes in gaps between component parts of the valve gear.
  • a typical lash adjuster for use in a swing arm type valve gear comprises a nut member inserted in a receiving hole formed in the top surface of the cylinder head, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with an internal thread formed on the inner periphery of the nut member, and a return spring biasing the adjusting screw in the direction to protrude upwardly from the nut member, thereby pivotally supporting the arm of the valve gear with the adjusting screw (Patent document 1).
  • a typical lash adjuster for use in a rocker arm type valve gear comprises a nut member inserted in a receiving hole formed in the bottom surface of the arm, which pivots as the cam rotates, an adjusting screw having an external thread on its outer periphery which is in threaded engagement with an internal thread formed on the inner periphery of the nut member, and a return spring biasing the adjusting screw in the direction to protrude downwardly from the nut member, thereby pressing the valve stem of the valve gear (Patent document 2).
  • a lash adjuster in which, in order fix the adjusting screw so as not to protrude from the nut member (initial set position), the adjusting screw is fixed in position by wax contained in the nut member (Patent document 3).
  • An object of the present invention is to provide a lash adjuster of which the lash adjuster can be repeatedly fixed in the initial set position.
  • an initial setting member is detachably disposed between the adjusting screw and the nut member so that the adjusting screw is fixed to the nut member due to frictional forces between the initial setting member and the adjusting screw and between the initial setting member and the nut member.
  • This lash adjuster may have e.g. one of the following structures:
  • the initial setting member may have e.g. one of the following structures:
  • a jig-inserting hole ( 30 ) may be formed in the operating tab portion of the initial setting member of the structure 1b) or 1c). With this arrangement, it is possible to pull out the initial setting member by inserting a jig in the jig-inserting hole, thus making it easier to release the initial set position.
  • the adjusting screw may comprise a pivot member axially slidably inserted in the nut member, an externally threaded member supporting the end of the pivot member inserted in the nut member and having the external thread on an outer periphery thereof, and an elastic member disposed between the pivot member and the externally threaded member.
  • the cut-out may be formed on the outer periphery of the pivot member.
  • the cut-out may be a D-cut portion or comprise two chamfers formed on the outer periphery of the adjusting screw.
  • cut-out is formed so as to separate the external thread on the adjusting screw into a plurality of sections, a plurality of such cut-outs are formed so as be circumferentially equidistantly spaced from each other.
  • the initial setting member may further comprise a pull-out portion which can be engaged by a finger, whereby the initial setting member can be pulled out of the insertion opening with the finger. This makes it easier to release the initial set position.
  • the initial setting member is preferably made of rubber or resin because such an initial setting member is lighter in weight than one made of a metal such as iron.
  • the present invention is applicable e.g. to the following lash adjusters:
  • the adjusting screw since the adjusting screw is fixed in position using the detachable initial setting member, the adjusting screw can be repeatedly set in the initial set position.
  • initial setting is complete simply by threading the adjusting screw all the way and it is never necessary to finely adjust the turning amount of the adjusting screw.
  • initial setting is easy.
  • FIG. 1 is a front view of a valve gear including a lash adjuster according to a first embodiment of the present invention.
  • FIG. 2 is an enlarged sectional view of the lash adjuster shown in FIG. 1 , showing the state before the lash adjuster is fixed in an initial set position.
  • FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 2 .
  • FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. 2 .
  • FIG. 5 is an enlarged sectional view of the lash adjuster shown in FIG. 2 , showing the initial set position of the adjusting screw.
  • FIG. 6 is a front view of the lash adjuster when the initial set position of the adjusting screw has been released.
  • FIG. 7 is a enlarged perspective view of a modification of an initial setting member shown in FIGS. 2 to 4 .
  • FIG. 8 shows how the adjusting screw is fixed in the initial set position by the initial setting member shown in FIG. 7 .
  • FIG. 9 is an enlarged perspective view of another modification of the initial setting member shown in FIGS. 2 to 4 .
  • FIG. 10 shows how the adjusting screw is fixed in the initial set position by the initial setting member shown in FIG. 9 .
  • FIG. 11 is a front view of a valve gear including a lash adjuster according to a second embodiment of the present invention.
  • FIG. 12 is an enlarged sectional view of the lash adjuster of FIG. 11 and its surroundings.
  • FIG. 13 is a front view of a valve gear including a lash adjuster according to a third embodiment of the present invention.
  • FIG. 14 is an enlarged sectional view of the lash adjuster shown in FIG. 13 .
  • FIG. 15 is a sectional taken along line XV-XV of FIG. 14 .
  • FIG. 16 is an enlarged sectional view of the lash adjuster showing how an elastic portion of an initial setting member shown in FIG. 14 is inserted in an insertion opening.
  • FIG. 17 is an enlarged sectional view of the lash adjuster showing the state in which the elastic portion of the initial setting member shown in FIG. 14 has been pulled out of the insertion opening.
  • FIG. 18 is a perspective view of the initial setting member shown in FIG. 14 .
  • FIG. 19 is a sectional view of a modification of the lash adjuster of FIG. 14 .
  • FIG. 20 is a sectional view taken along line XX-XX of FIG. 19 .
  • FIG. 21 is an enlarged sectional view of the lash adjuster showing the state in which a elastic portion of an initial setting member shown in FIG. 19 has been pulled out of an insertion opening.
  • FIG. 22 is a front view of a valve gear including a lash adjuster according to a fourth embodiment of the present invention.
  • FIG. 23 is an enlarged sectional view of the lash adjuster shown in FIG. 22 .
  • FIG. 24 is a sectional view taken along line XXIV-XXIV of FIG. 23 .
  • FIG. 25 is an enlarged sectional view of a lash adjuster according to a fifth embodiment of the present invention.
  • FIG. 26 is a sectional view taken along line XXVI-XXVI of FIG. 25 .
  • FIG. 1 shows a valve gear including the lash adjuster 1 according to the first embodiment of the present invention.
  • This valve gear includes a valve 4 provided at an intake port 3 of a cylinder head 2 of an engine, a valve stem 5 connected to the valve 4 , and a arm 7 pivotable as a cam 6 rotates.
  • the valve stem 5 extends upwardly from the valve 4 and slidably through the cylinder head 2 .
  • An annular spring retainer 8 is fixed to the outer periphery of the valve stem 5 at its upper portion.
  • a valve spring 9 is mounted between the bottom surface of the spring retainer 8 and the top surface of the cylinder head 2 . The valve spring 9 biases the valve stem 5 upwardly through the spring retainer 8 , thereby seating the valve 4 on a valve seat 10 .
  • the arm 7 has one end thereof pivotally supported by the lash adjuster 1 and the other end kept in contact with the top end of the valve stem 5 .
  • the arm 7 carries a roller 11 which is pressed by the cam 6 , which is provided over the roller 11 .
  • the cam 6 is integrally formed on a camshaft 12 which rotates in unison with the engine crankshaft (not shown).
  • the lash adjuster 1 comprises a cylindrical nut member 14 received in a receiving hole 13 formed in the top surface of the cylinder head 2 , an adjusting screw 17 having an external thread 16 on its outer periphery at its lower portion which is in threaded engagement with an internal thread 15 formed on the inner periphery of the nut member 14 , and a return spring 19 mounted between the adjusting screw 17 and a bottom portion 18 of the nut member 14 .
  • the external thread 16 and the internal thread 15 each have a pressure flank 20 that receives pressure when a load is applied that tends to push the adjusting screw 17 into the nut member 14 .
  • the pressure flank 20 has a flank angle larger than the clearance flank 21 so that the threads 16 and 15 have a serration-shaped section.
  • the pressure flanks 20 of the external thread 16 and the internal thread 15 may have a flank angle of 75°, while their clearance flanks 21 may have a flank angle of 15°.
  • the return spring 19 is a compression spring and is mounted in the nut member 15 while being axially compressed.
  • the return spring 19 has its bottom end supported on the bottom portion 18 of the nut member 14 , and applies, at its top end, an axial force to the adjusting screw 17 through a spring seat 22 that tends to push the adjusting screw 17 out of the nut member 14 , thereby biasing the adjusting screw 17 in the direction to protrude upwardly from the nut member 14 .
  • the adjusting screw 17 has a head 23 having an outer diameter larger than the inner diameter of the nut member 14 .
  • the head 23 is engaged in a recess 24 formed in the bottom surface of the art 7 at its end portion, thereby supporting the arm 7 .
  • the head 23 has a hemispherical contact surface that is in contact with the recess 24 .
  • the arm 7 is pivotable due to sliding between the head 23 and the recess 24 .
  • an initial setting member 25 formed by bending a metal wire is inserted between the bottom end surface of the head 23 and the top end surface of the nut member 14 .
  • the initial setting member 25 comprises arm portions 26 diametrically opposed to each other with the adjusting screw 17 disposed therebetween, and an operating tab portion 27 connecting together ends of the respective arm portions 26 .
  • the arm portions 26 each have a corrugated portion disposed between the bottom end surface of the head 23 and the top end surface of the nut member 14 .
  • the corrugated portions are formed by bending the wire in a corrugated shape so as to be axially elastically deformable.
  • the lash adjustor 1 is assembled into the valve gear e.g. in the following manner.
  • the lash adjuster 1 is inserted into the receiving hole 13 of the cylinder head 2 , and the arm 7 and the camshaft 12 are mounted in position.
  • the initial setting member 25 is pulled out from between the head 23 of the adjusting screw 17 and the nut member 14 , thus releasing the initial set position.
  • the adjusting screw 17 thus protrudes while rotating under the biasing force of the return spring 19 , thus pushing up the end of the arm 7 until the roller 11 contacts the cam 6 .
  • valve stem 5 rises under the biasing force of the valve spring 9 , thereby seating the valve 4 against the valve seat 10 , closing the intake port 3 .
  • the adjusting screw 17 protrudes by a larger amount when the cam 6 further rotate after the cam lobe 6 a of the cam 6 presses down the arm 7 until the load is removed, than the amount by which the adjusting screw 17 is pushed in when the arm 7 is pressed down by the cam lobe 6 a of the cam 6 .
  • the adjusting screw 17 protrudes gradually, thus preventing any gap between the base circle 6 b of the cam 6 and the roller 11 .
  • the biasing force of the valve spring 9 keeps acting on the adjusting screw 17 even while the base circle 6 b of the cam 6 faces the roller 11 .
  • the adjusting screw 17 protrudes by a smaller amount when the cam 6 further rotate after the cam lobe 6 a of the cam 6 presses down the arm 7 until the load is removed, than the amount by which the adjusting screw 17 is pushed in when the arm 7 is pressed down by the cam lobe 6 a of the cam 6 .
  • the adjusting screw 17 is pushed in gradually, allowing the valve stem 5 to rise. This prevents any gap between the contact surfaces of the valve 4 and the valve seat 10 .
  • the adjusting screw 17 protrudes from the nut member 14 under the biasing force of the return spring 19 .
  • the adjusting screw 17 can be again set in the initial set position.
  • the adjusting screw 17 can be fixed in position using the detachably inserted initial setting member 25 , the adjusting screw 17 can be repeatedly set in the initial set position.
  • the initial setting member to be disposed between the head 23 of the adjusting screw 17 and the nut member 14 is the initial setting member 25 formed by bending a metal wire material.
  • an initial setting member 28 as shown in FIGS. 7 and 8 may be used, which is formed by pressing a metal sheet material.
  • the initial setting member 28 comprises two diametrically opposed arm portions 29 , and an operating tab portion 30 connecting together two respective ends of the arm portions 29 .
  • the arm portions 29 each have a corrugated portion disposed between the bottom end surface of the head 23 and the top end surface of the nut member 14 .
  • the corrugated portions are formed by bending the sheet material in a corrugated shape so as to be axially elastically deformable.
  • the operating tab portion 30 is formed with a vertically extending jig-inserting through hole 31 .
  • the initial setting member 28 can be pulled out by inserting a jig (not shown) into the jig-inserting hole 31 .
  • an initial setting member 32 shown in FIGS. 9 and 10 may be used, which is formed by injection-molding an elastic resin.
  • the initial setting member 32 comprises two diametrically opposed arm portions 33 , and an operating tab portion 34 connecting together two respective ends of the arm portions 33 .
  • the operating tab portion 34 is formed with a vertically extending jig-inserting through hole 35 .
  • the initial setting member 32 can be pulled out by inserting a jig into the jig-inserting hole 35 .
  • FIG. 11 shows a valve gear to which the lash adjuster 41 of the second embodiment according to this invention is mounted.
  • This valve gear includes a valve 44 provided at an intake port 43 of a cylinder head 42 of an engine, a valve stem 45 connected to the valve 44 , and an arm 47 that pivots as a cam 46 rotates.
  • valve stem 45 extends upwardly from the valve 44 .
  • a spring retainer 48 is fixed to the upper portion of the valve stem 45 .
  • a valve spring 49 biases the spring retainer 48 , thereby seating the valve 44 against a valve seat 50 .
  • the arm 47 has its central portion pivotally supported by a pivot shaft 51 , and carries at one end thereof a roller 52 that is in contact with the cam 46 .
  • the lash adjuster 41 is mounted to the other end of the arm 47 .
  • the cam 46 which is provided under the arm 47 , rotates together with the engine crankshaft (not shown), thereby pivoting the arm 47 by pressing the roller 52 with its cam lobe 46 b, which protrudes from its base circle 46 a.
  • the lash adjuster 41 comprises a tubular nut member 54 inserted in a mounting hole 53 formed in the bottom surface of the arm 47 , an adjusting screw 57 having an external thread 56 on its outer periphery at its upper portion which is in threaded engagement with an internal thread 55 formed on the inner periphery of the nut member 54 , and a return spring 59 mounted between the adjusting screw 57 and the inner bottom surface 58 of the mounting hole 53 .
  • the external thread 56 and the internal thread 55 each have a pressure flank 60 that receives pressure when a load is applied that tends to push the adjusting screw 57 into the nut member 54 .
  • the pressure flank 60 has a flank angle larger than the clearance flank 61 so that the threads 56 and 55 have a serration-shaped section.
  • the return spring 59 is a compression coil spring having its top end supported by the inner bottom surface 58 of the mounting hole 53 and applies, at its bottom end, an axial force to the adjusting screw 57 through a spring seat 62 that tends to push the adjusting screw 57 out of the nut member 54 , thereby biasing the adjusting screw 57 in the direction to protrude downwardly from the nut member 54 .
  • the adjusting screw 57 has a head 63 having an outer diameter larger than the inner diameter of the nut member 54 .
  • the head 63 presses the top end of the valve stem 45 .
  • the same initial setting member 25 as used in the first embodiment is inserted between the top end surface of the head 63 and the bottom end surface of the nut member 54 .
  • the initial setting member 25 comprises the diametrically opposed arm portions 26 and the operating tab 27 connecting together two respective ends of the arm portions 26 .
  • the adjusting screw 57 can be fixed in position using the detachably inserted initial setting member 25 , the adjusting screw 57 can be repeatedly set in the initial set position. Since initial setting is complete simply by threading the adjusting screw 57 into the nut member 54 , initial setting is easy. Also, since it is not necessary to form through holes for inserting a set pin in the adjusting screw 57 and the nut member 54 , its manufacturing cost is low.
  • FIG. 13 shows the lash adjuster 71 of the third embodiment. Elements corresponding to those of the first embodiment are denoted by identical numerals and their description is omitted.
  • the adjusting screw 17 has a hemispherical protruding end 72 protruding from the nut member 14 .
  • the protruding end 72 is fitted in a recess 24 formed in the bottom surface of the arm 7 and supports the arm 7 .
  • the arm 7 pivotable as the protruding end 72 slides in the recess 24 .
  • an axial groove 73 is formed in the outer periphery of the adjusting screw 17 to extend across the external thread 16 from its top to bottom ends.
  • the axial groove 73 thus separates the external thread 16 into a plurality of sections.
  • the axial groove 73 has a U-shaped section, and defines an insertion opening 74 between the adjusting screw 17 and the nut member 14 .
  • An initial setting member 75 is detachably inserted in the insertion opening 74 .
  • the initial setting member 75 comprises an elastic portion 76 inserted in the insertion opening 74 , a ring-shaped pull-out portion 77 , and a connecting portion 78 connecting the pull-out portion 77 to the elastic portion 76 .
  • the initial setting member 75 is integrally formed from resin or rubber.
  • the elastic portion 76 is a bifurcated member having arms extending in the direction opposite to the direction in which the elastic portion 76 is inserted.
  • the elastic portion 76 is thus elastically compressed between the inner surface of the axial groove 73 and the pressure flank 20 of the internal thread, thereby producing elastic restoring force, which in turn produces frictional forces between the elastic portion 76 and the adjusting screw 17 and between the elastic portion 76 and the nut member 14 .
  • These frictional forces prevent rotation of the adjusting screw 17 , thus keeping the adjusting screw 17 from protruding from the nut member 14 .
  • the elastic portion 76 has a stopper 79 adapted to abut the top end of the nut member 14 when the elastic portion 76 is inserted into the insertion opening 74 .
  • a through hole 80 is formed in the bottom 18 of the nut member 14 that extends vertically through the bottom 18 .
  • an oil discharge hole 81 is formed in the inner bottom surface of the mounting hole 13 which communicates with the through hole 80 .
  • the lash adjuster 71 is mounted to the valve gear e.g. as follows.
  • the adjusting screw 17 is fixed in the initial set position by inserting the initial setting member 75 in the insertion opening 74 .
  • the lash adjuster 71 is inserted into the mounting hole 13 , and the arm 7 and the camshaft 12 are mounted in position.
  • the initial setting member 75 is pulled out of the insertion opening 74 by engaging a finger or a tool with the pull-out portion 77 .
  • this lash adjuster 71 it is possible to fix the adjusting screw 75 in the initial set position at any desired height by screwing the adjusting screw 17 to the desired height, and then inserting the initial setting member 75 into the insertion opening 74 .
  • the adjusting screw 17 can be fixed in the initial set position at any desired height according to the kind of the valve lifter used.
  • the initial setting member 75 is made of resin or rubber, the initial setting member 75 is lighter in weight than a similar initial setting member made of a metal such as iron.
  • the initial setting member 75 is preferably made of resin because it is more easily recyclable.
  • the elastic portion 76 of the initial set member 75 is bifurcated. But as shown in FIGS. 19 to 21 , the elastic portion 76 may be spherically shaped. In FIGS. 19 to 21 , the spherical elastic portion 76 is sized such that it is elastically compressed when inserted into the insertion opening 74 .
  • FIG. 15 only one axial groove 73 may be formed. But as shown in FIG. 20 , a plurality of circumferentially equidistantly spaced axial grooves 73 may be formed. With this arrangement, since the external thread 16 and the internal thread 15 axially symmetrically contact each other, the adjusting screw 17 is less likely to incline while the engine is running. Also, if the adjusting screw 17 is formed by forging, forging can be done with higher accuracy.
  • the axial groove 73 is formed in the outer periphery of the adjusting screw 17 .
  • such an axial groove may be formed in the inner periphery of the nut member 14 instead of in the outer periphery of the adjusting screw 17 .
  • such axial grooves may be formed both in the outer periphery of the adjusting screw 17 and in the inner periphery of the nut member 14 .
  • the cut-out defining the insertion opening 74 is the axial groove 73 .
  • the insertion opening may be defined by a D-cut portion or two chamfers formed on the outer periphery of the adjusting screw 17 .
  • the D-cut portion is a cut-out on the outer surface of the adjusting screw 17 extending along a plane parallel to a plane including the axis of the adjusting screw 17 .
  • the two chamfers are two flat surfaces formed by cutting out the outer periphery of the adjusting screw 17 so as to extend parallel to a plane including the axis of the adjusting screw 17 .
  • a compression coil spring is used as the return spring 19 for biasing the adjusting screw 17 .
  • a torsion coil spring may be used instead of a compression coil spring.
  • the external thread 16 and the internal thread 15 may be trapezoidal threads or triangular threads.
  • FIGS. 22 and 24 show the lash adjuster 91 of the fourth embodiment according to this invention. Elements corresponding to those of the second embodiment are denoted by identical numerals and their description is omitted.
  • the return spring 59 is a torsion coil spring having its top end engaged in a through hole 92 formed in the inner bottom surface of the mounting hole 53 slit and rotationally fixed in position, and its bottom end engaged in an engaging hole 93 formed in the adjusting screw 57 , thereby applying torque to the adjusting screw 57 that tends to push the adjusting screw 57 downwardly out of the nut member 54 by its torsional deformation.
  • the adjusting screw 57 is thus biased by this torque in the direction to protrude downwardly from the nut member 54 .
  • the protruding portion of the adjusting screw 57 protruding from the nut member 54 is in abutment with the top end of the valve stem 45 , thereby pressing the valve stem 45 .
  • the external thread 56 and the internal thread 55 are vertically symmetrical triangular threads.
  • an axial groove 95 is formed in the outer periphery of the adjusting screw 57 to extend across the external thread 56 from its top to bottom ends. The axial groove 95 thus separates the external thread 56 into a plurality of sections.
  • Another axial groove 96 is formed in the inner periphery of the nut member 54 to extend across the internal thread 55 from its top to bottom ends, thus separating the internal thread 55 into a plurality of sections.
  • the axial groves 95 and 96 have a U-shaped section, and radially align with each other, defining an insertion opening 97 between the adjusting screw 57 and the nut member 54 .
  • the same initial setting member 75 as used in the third embodiment is detachably inserted in the insertion opening 97 .
  • the elastic portion 76 of the initial setting member 75 is elastically compressed between the inner surface of the axial groove 95 and the inner surface of the axial groove 96 , thus producing radial elastic restoring force.
  • frictional forces are produced between the elastic portion 76 and the adjusting screw 57 and between the elastic portion 76 and the nut member 54 . These frictional forces keep the adjusting screw 57 in the initial set position.
  • the nut member 54 is open at both ends.
  • engine oil flowing into the mounting hole 53 through the through hole 92 flows into the gap between the external thread 56 and the internal thread 55 , and is discharged through the bottom end of the nut member 54 .
  • the lash adjuster 91 is mounted to the valve gear e.g. as follows.
  • the adjusting screw 57 is fixed in the initial set position by inserting the initial setting member 75 in the insertion opening 97 . Then as shown in FIG. 22 , the arm 47 and the cam 46 are mounted to the valve gear. In this state, the initial setting member 75 is pulled out of the insertion opening 97 . This releases the initial set position of the adjusting screw 57 , and the adjusting screw 57 protrudes from the mounting hole while rotating under the torque of the return spring 59 , thus pressing the top end of the valve stem 45 .
  • this lash adjuster 91 it is possible to fix the adjusting screw 75 in the initial set position at any desired height per pitch of the external thread 56 by screwing the adjusting screw 57 to the desired height until the axial grooves 95 and 96 are radially aligned with each other, and then inserting the initial setting member 75 into the insertion opening 97 .
  • the adjusting screw 57 can be fixed in the initial set position at any desired height according to the kind of the valve lifter used.
  • the axial grooves 95 and 96 are formed in the outer periphery of the adjusting screw 57 and in the inner periphery of the nut member 54 , respectively. But only one of them is sufficient. A plurality of circumferentially equidistantly spaced axial grooves 95 and 96 may be formed. With this arrangement, since the external thread 56 and the internal thread 55 axially symmetrically contact each other, the adjusting screw 57 is less likely to incline while the engine is running.
  • the axial grooves 95 and 96 which have a U-shaped section, are formed in the outer periphery of the adjusting screw 57 and the inner periphery of the nut member 54 , respectively.
  • a D-cut portion or two chamfers may be formed on the outer periphery of the adjusting screw 57 .
  • the external thread 56 and the internal thread 55 may be trapezoidal threads.
  • FIGS. 25 and 26 show the lash adjuster 101 of the fifth embodiment according to this invention. Elements corresponding to those of the fifth embodiment are denoted by identical numerals and their description is omitted.
  • 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 the end of the pivot member 17 A inserted in the nut member 14 and having an external thread 16 on its outer periphery, and a spring washer 17 C disposed between the pivot member 17 A and the externally threaded member 17 B.
  • the spring washer 17 C may be e.g. a disk spring washer or a wave washer.
  • a D-cut portion 102 is formed on the outer periphery of the pivot member 17 A to extend from its portion protruding from the nut member 14 to its end inserted in the nut member 14 . As shown in FIG. 26 , the D-cut portion 102 defines an insertion opening 74 between the pivot member 17 A and the nut member 14 .
  • the return spring 19 applies an axial force to the externally threaded member 17 B through a spring seat 22 that tends to push the pivot member 17 A out of the nut member 14 .
  • this lash adjuster 101 as in the third embodiment, it is possible to fix the adjusting screw 17 in the initial set position at any desired height by screwing the adjusting screw 17 to the desired height and inserting the initial setting member 75 into the insertion opening 74 in this state. Also, since the adjusting screw 17 is fixed in the initial set position using the detachable initial setting member 75 , the adjusting screw 17 can be repeatedly fixed in the initial set position.
  • the cut-out for defining the insertion opening 74 is the D-cut portion 102 .
  • the insertion opening 74 may be defined by two chamfers or an axial groove.
  • a cut-out may be formed on the inner periphery of the nut member 14 that extends downwardly from its top end.
  • the spring washer 17 C is used as an elastic member to be disposed between the pivot member 17 A and the externally threaded member 17 B.
  • the spring washer 17 C may be replaced by a different elastic member (such as a compression coil spring).

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Valve-Gear Or Valve Arrangements (AREA)
US12/922,695 2008-03-27 2009-03-18 Lash adjuster Abandoned US20110017161A1 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP2008-083362 2008-03-27
JP2008083362A JP2009236007A (ja) 2008-03-27 2008-03-27 ラッシュアジャスタ
JP2008-211537 2008-08-20
JP2008211537A JP2010048124A (ja) 2008-08-20 2008-08-20 ラッシュアジャスタ
PCT/JP2009/055249 WO2009119398A1 (ja) 2008-03-27 2009-03-18 ラッシュアジャスタ

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100263613A1 (en) * 2007-12-07 2010-10-21 Makoto Yasui Lash adjuster
US20120227695A1 (en) * 2009-12-18 2012-09-13 Masashi Bokura Arm type valve lifter
US20160210871A1 (en) * 2015-01-19 2016-07-21 The Boeing Company Instructional Assessment System for a Vehicle
US11008901B1 (en) 2019-11-22 2021-05-18 Caterpillar Inc. Rocker arm assembly with air venting
US11454139B2 (en) * 2016-07-19 2022-09-27 Eaton Intelligent Power Limited Method for valvetrain lash adjustment with extra lost motion stroke and high stiffness lost motion spring

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US3791355A (en) * 1972-02-24 1974-02-12 Johnson Products Inc Mechanical lash adjuster for overhead cam engines

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JPH07650Y2 (ja) * 1987-10-13 1995-01-11 エヌティエヌ株式会社 ラッシュアジャスタ装置
JP3794836B2 (ja) 1998-10-05 2006-07-12 Ｎｔｎ株式会社 バルブリフタ
JP4215663B2 (ja) 2004-03-08 2009-01-28 Ｎｔｎ株式会社 バルブクリアランス自動調整装置
JP2007092668A (ja) 2005-09-29 2007-04-12 Ntn Corp アーム式動弁装置
WO2009041364A1 (ja) * 2007-09-26 2009-04-02 Ntn Corporation ラッシュアジャスタ

Patent Citations (1)

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Publication number Priority date Publication date Assignee Title
US3791355A (en) * 1972-02-24 1974-02-12 Johnson Products Inc Mechanical lash adjuster for overhead cam engines

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20100263613A1 (en) * 2007-12-07 2010-10-21 Makoto Yasui Lash adjuster
US20120227695A1 (en) * 2009-12-18 2012-09-13 Masashi Bokura Arm type valve lifter
US20160210871A1 (en) * 2015-01-19 2016-07-21 The Boeing Company Instructional Assessment System for a Vehicle
US11454139B2 (en) * 2016-07-19 2022-09-27 Eaton Intelligent Power Limited Method for valvetrain lash adjustment with extra lost motion stroke and high stiffness lost motion spring
US11008901B1 (en) 2019-11-22 2021-05-18 Caterpillar Inc. Rocker arm assembly with air venting

Also Published As

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DE112009000725T5 (de) 2011-02-24
WO2009119398A1 (ja) 2009-10-01

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