US20110036314A1 - Lash adjuster - Google Patents
Lash adjuster Download PDFInfo
- Publication number
- US20110036314A1 US20110036314A1 US12/921,587 US92158709A US2011036314A1 US 20110036314 A1 US20110036314 A1 US 20110036314A1 US 92158709 A US92158709 A US 92158709A US 2011036314 A1 US2011036314 A1 US 2011036314A1
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- United States
- Prior art keywords
- case
- lash adjuster
- mounting hole
- adjusting screw
- rotation
- 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
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Classifications
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- 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
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- 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
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- 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.
- One known valve gear for moving a valve provided at an intake port or an exhaust port of an engine includes an arm pivotable about one end thereof and adapted to be pressed down at its mid-portion by a cam, thereby pressing down the valve stem at its other end.
- valve gear While the engine is running, due to differences in thermal expansion between component parts of the valve gear, gaps between component parts of the valve gear may change, thereby producing noise or causing pressure leakage. When sliding parts of the valve gear become worn too, gaps between component parts of the valve gear change, thus producing noise or causing pressure leakage.
- a typical valve gear includes a lash adjuster to eliminate gaps between component parts of the valve gear.
- such a lash adjuster comprises a cylindrical case having a bottom and received in a mounting hole formed in the top surface of the cylinder head, an adjusting screw having an external thread on the outer periphery thereof which is in threaded engagement with an internal thread formed on the inner periphery of the case, and a return spring biasing the adjusting screw in the direction to protrude upwardly from the case, thereby pivotally supporting the arm of the valve gear at the protruding end of the adjusting screw protruding from the case (Patent documents 1 and 2).
- the return spring is a compression coil spring that applies an axial force to the adjusting screw that tends to push the adjusting screw out of the case.
- the return spring is a torsion spring that applies torque to the adjusting screw that tends to push the adjusting screw out of the case.
- the adjusting screw axially moves in the case while rotating relative to the case, thereby absorbing the change in gaps between component parts of the valve gear.
- Patent document 1 JP Patent Publication 2005-273510A
- Patent document 2 JP Patent Publication 64-34407A
- the case may rotate relative to the mounting hole under the force that acts between the thread surfaces of the adjusting screw and the case. If the case rotates, the adjusting screw is pushed into the case, reducing the valve lift. Rotation of the case would also quicken wear of the mounting hole.
- An object of the present invention is to prevent rotation of the case when a load is applied to the adjusting screw that tends to push in the adjusting screw.
- the lash adjuster is provided with an anti-rotation means for preventing rotation of the case.
- the anti-rotation means may comprise an anti-rotation protrusion provided on the bottom of the case, and a fitting port formed in an inner bottom surface of the mounting hole, in which the anti-rotation protrusion is fitted.
- the anti-rotation protrusion may be a protrusion having a D-cut portion on an outer periphery thereof, a protrusion having two chamfers on an outer periphery thereof, a protrusion in the shape of a regular polygonal column, or a protrusion offset from an axis of the case.
- the fitting port may be one end of an air vent hole extending from the inner bottom surface of the mounting hole to outside.
- a through hole may be formed to extend vertically through the bottom of the case, with a bottom end thereof open to a free end of the anti-rotation protrusion.
- the anti-rotation means may be a friction ensuring means for ensuring frictional resistance between the bottom of the case and the inner surface of the mounting hole, thereby preventing rotation of the case.
- the friction ensuring means comprises an oil film expelling groove formed in an outer bottom surface of the case.
- the friction ensuring means may comprise a satin-finished surface formed on the outer bottom surface of the case.
- the outer bottom surface of the case may be satin-finished by electric discharge machining or laser machining. But preferably, it is satin-finished by shot peening, because shot peening hardens the outer bottom surface of the case, thereby increasing its wear resistance.
- the friction ensuring means may comprise a tapered outer peripheral surface formed on the bottom of the case and having a downwardly decreasing diameter, and a tapered inner peripheral surface formed on the mounting hole and having a downwardly decreasing diameter, with the tapered outer peripheral surface engaged in the tapered inner peripheral surface.
- the friction ensuring means may comprise a recess formed in the outer bottom surface of the case except its peripheral edge.
- frictional resistance produced between the outer bottom surface of the case and the inner bottom surface of the mounting hole concentrates on the radially outer side, so that it is possible to ensure sufficient frictional resistance for preventing rotation of the case.
- a similar recess may be formed in the inner bottom surface of the mounting hole except its peripheral edge as the friction ensuring means.
- the friction ensuring means may comprise a small-diameter inner peripheral portion formed on the mounting hole, the bottom of the case being press-fitted in the small-diameter inner peripheral portion.
- the friction ensuring means may comprise a sheet made of rubber or an elastomer and disposed between an outer bottom surface of the case and the inner bottom surface of the mounting hole.
- the friction ensuring means may comprise a seat made of iron and forming the inner bottom surface of the mounting hole.
- the friction ensuring means may comprise a sleeve made of iron and forming the mounting hole.
- the return spring may be a compression coil spring that applies an axial force to the adjusting screw that tends to push the adjusting screw out of the case.
- the return spring may be a torsion spring that applies torque to the adjusting screw that tends to push the adjusting screw out of the case.
- the torsion spring may be one of a torsion coil spring, a spiral spring and a volute spring.
- the external thread and the internal thread are triangular threads, trapezoidal threads or serration-shaped threads.
- the lash adjuster according to this invention is provided with an anti-rotation means for preventing rotation of the case, the case is less likely to rotate when a load is applied to the adjusting screw that tends to push in the adjusting screw. This prevents reduction in the valve lift due to rotation of the case.
- the lash adjuster thus stably performs its function. Also, it is possible to prevent wear of the inner surface of the mounting hole.
- 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 of FIG. 1 and its surrounding area.
- FIG. 3 is a sectional view taken along line III-III of FIG. 2 .
- FIG. 4 is an enlarged view of a different anti-rotation protrusion from that of FIG. 2 .
- FIG. 5 is a sectional view taken along line V-V of FIG. 4 .
- FIG. 6 is an enlarged view of a still different anti-rotation protrusion from that of FIG. 2 .
- FIG. 7 is a sectional view taken along line VII-VII of FIG. 6 .
- FIG. 8 is an enlarged sectional view of a further different anti-rotation protrusion from that of FIG. 2 .
- FIG. 9 is a sectional view taken along line IX-IX of FIG. 8 .
- FIG. 10 is an enlarged sectional view of a lash adjuster according to a second embodiment of the present invention.
- FIG. 11 is an enlarged sectional view of a modification of the return spring shown in FIG. 10 .
- FIG. 12 is an enlarged sectional view of another modification of the return spring shown in FIG. 10 .
- FIG. 13 is a sectional view taken along line XIII-XIII of FIG. 12 .
- FIG. 14 is an enlarged sectional view of still another modification of the return spring shown in FIG. 10 .
- FIG. 15 is an enlarged sectional view of a lash adjuster according to a third embodiment of the present invention.
- FIG. 16 is a sectional view taken along line XVI-XVI of FIG. 15 .
- FIG. 17 is an enlarged sectional view of a modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 18 is an enlarged sectional view of another modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 19 is an enlarged sectional view of still another modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 20 is an enlarged sectional view of a further modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 21 is an enlarged sectional view of a still further modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 22 is an enlarged sectional view of still another modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 23 is an enlarged sectional view of still another modification of the means of ensuring friction shown in FIG. 15 .
- FIG. 1 shows a valve gear including a lash adjuster 1 according to a 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 , a lash adjuster 1 mounted in a mounting hole 6 formed in the top surface of the cylinder head 2 , and an arm 7 supported by the lash adjuster 1 so as to be pivotable about the lash adjuster 1 .
- 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 against a valve seat 10 by its biasing force.
- the arm 7 has one end thereof supported by the lash adjuster 1 and the other end in contact with the top end of the valve stem 5 . At its mid-portion, the arm 7 carries a roller 11 which is in contact with a cam 12 provided over the roller 11 .
- the lash adjuster 1 comprises a cylindrical case 13 having a bottom and inserted in the mounting hole 6 , an adjusting screw 16 having an external thread 15 on its outer periphery at its lower portion which is threaded engagement with an internal thread formed on the inner periphery of the case 13 , and a return spring 18 mounted between the adjusting screw 16 and the bottom 17 of the case 13 .
- the external thread 15 and the internal thread 14 each have a pressure flank that receives pressure when a load is applied that tends to push the adjusting screw 16 into the case 13 .
- the pressure flank 19 has a flank angle larger than the clearance flank 20 so that the threads 15 and 14 have a serration-shaped section.
- the return spring 18 is a compression coil spring having its bottom end supported by the bottom 17 of the case 13 and applies, at its top end, an axial force to the adjusting screw 16 through a spring seat 21 that tends to push the adjusting screw 16 upwardly out of the case 13 .
- the adjusting screw 16 has a protruding end 22 protruding from the case 13 and fitted in a recess 23 formed in the bottom surface of the arm 7 at its end, thus supporting the arm 7 so as to be pivotable about the protruding end 22 .
- An air vent hole 25 is formed in the cylinder head 2 to extend from an inner bottom surface 24 of the mounting hole 6 to outside.
- an anti-rotation protrusion 27 is formed on the bottom 17 of the case 13 which is fitted in a fitting port 26 formed in the inner bottom surface 24 of the mounting hole 6 .
- the fitting port 26 constitutes one end of the air vent hole 25 .
- the anti-rotation protrusion 27 has a D-cut portion 28 on its outer periphery which engages a D-cut portion 29 formed on the inner periphery of the fitting port 26 , thereby rotationally fixing the case 13 in position.
- the D-cut portion 28 is formed by cutting the outer periphery of the protrusion 27 along a plane parallel to a plane including the axis of the case 13 .
- the case 13 is made of iron to ensure strength of the internal thread 14 .
- the fitting port 26 which has the D-cut portion 29 on its inner periphery, and the air vent hole 25 , which has the fitting port 26 at one end, can be formed when forming the cylinder head 2 by die-casting aluminum.
- a through hole 30 extends vertically through the bottom 17 of the case 13 with its bottom open to the bottom end surface of the anti-rotation protrusion 27 .
- valve stem 5 rises under the biasing force of the valve spring 9 , so that the valve 4 is seated on the valve seat 10 , closing the intake port 3 .
- the adjusting screw 16 protrudes by a larger amount when the cam 12 further rotate after the cam lobe 12 a of the cam 12 presses down the arm 7 until the load is removed, than the amount by which the adjusting screw 16 is pushed in when the arm 7 is pressed down by the cam lobe 12 a of the cam 12 .
- the adjusting screw 16 protrudes gradually, thus preventing any gap between the base circle 12 b of the cam 12 and the roller 11 .
- the biasing force of the valve spring 9 keeps acting on the adjusting screw 16 even while the base circle 12 b of the cam 12 faces the roller 11 .
- the adjusting screw 16 protrudes by a smaller amount when the cam 12 further rotates after the cam lobe 12 a of the cam 12 presses down the arm 7 until the load is removed, than the amount by which the adjusting screw 16 is pushed in when the arm 7 is pressed down by the cam lobe 12 a of the cam 12 .
- the cam 12 rotates once, the adjusting screw 16 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 lash adjuster 1 when the lash adjuster 1 is inserted into the mounting hole 6 , air between the bottom 17 of the case 13 and the inner bottom surface 24 of the mounting hole 6 is discharged through the air vent hole 25 , so that the interior of the mounting hole 6 is kept at the atmospheric pressure, which prevents reaction force from acting on the bottom 17 of the case.
- the lash adjuster can be mounted easily in the cylinder head 2 . Since one end of the air vent passage 25 is used as the fitting port 26 , there is no need to form the fitting port 26 separately from the air vent hole 25 , which makes easier to form the cylinder head 2 .
- the anti-rotation protrusion 27 provided on the bottom 17 of the case 13 is the anti-rotation protrusion 27 having the D-cut portion 28 on the outer periphery.
- an anti-rotation protrusion 32 having two chamfers 31 may be used instead of this anti-rotation protrusion 27 .
- the anti-rotation protrusion 32 can be fitted in the fitting port 33 even when the case 13 is rotated by 180°, the lash adjuster 1 can be more easily mounted in the cylinder head 2 .
- the two chamfers 31 are two flat surfaces that are parallel to a plane including the axis of the case 13 .
- an anti-rotation protrusion 35 in the shape of a regular polygonal column (such as a regular hexagonal column) 35 may be used instead of the anti-rotation protrusion 27 .
- an anti-rotation protrusion 35 in the shape of a regular polygonal column such as a regular hexagonal column
- the anti-rotation protrusion 35 can be fitted in the fitting port 36 at a plurality of different angular positions of the case 13 , the lash adjuster 1 can be further easily mounted in the cylinder head 2 .
- the anti-rotation protrusion 27 may also be replaced by an anti-rotation protrusion 37 which is offset from the axis of case 13 .
- This anti-rotation protrusion 37 is engaged in a fitting port 38 which is offset from the axis of the mounting hole 6 to prevent rotation of the case 13 .
- FIG. 10 shows a lash adjuster 41 according to the second embodiment of the present invention.
- this lash adjuster 41 includes the same anti-rotation protrusion 27 as in the first embodiment, i.e. the one having the D-cut portion 28 on the outer periphery.
- elements corresponding to those of the first embodiment are denoted by identical numerals and their description is omitted.
- the adjusting screw 16 comprises a pivot member 16 A axially slidably inserted in the case 13 , an externally threaded member 16 B supporting the end of the pivot member 16 A inserted in the case 13 and having the external thread 15 on the outer periphery, and a disc spring 16 C disposed between the pivot member 16 A and the externally threaded member 16 B.
- the return spring 18 is a torsion coil spring having its bottom end engaged in an engaging hole 42 formed in the bottom 17 of the case 13 , and its top end engaged in an engaging hole 43 formed in the externally threaded member 16 B. Due to its torsional deformation, the return spring 18 applies torque to the externally threaded member 16 B in the direction to push the pivot member 16 A out of the case 13 .
- the anti-rotation protrusion 27 On the bottom 17 of the case 13 , the anti-rotation protrusion 27 having the D-cut portion 28 on the outer periphery. The anti-rotation protrusion 27 is engaged in the fitting port 26 formed in the inner bottom surface 24 of the mounting hole 6 .
- the return spring 18 is a torsion coil spring
- the return spring 18 may be a cylindrically wound one as shown in FIG. 10 , or a conically wound one as shown in FIG. 11 .
- the return spring 18 may be a torsion spring other than a torsion coil spring.
- the return spring 18 shown in FIGS. 12 and 13 is a volute spring formed by helically winding a thin sheet material.
- This return spring 18 has its radially outer end rotationally fixed to the bottom 17 of the case 13 , and its radially inner end fitted in a slit formed in a protrusion 44 at the end of the externally threaded member 16 B inserted in the case 13 . Due to its torsional deformation, the return spring 18 applies torque to the externally threaded member 16 B in the direction to push the pivot member 16 A out of the case 13 .
- the external thread 15 on the outer periphery of the externally threaded member 16 B and the internal thread 14 on the inner periphery of the case 13 are vertically symmetrical trapezoidal threads.
- the return spring 18 shown in FIG. 14 is a spiral spring formed by spirally winding a thin sheet material.
- This return spring 18 has its radially outer end rotationally fixed to the bottom 17 of the case 13 , and its radially inner end fitted in a slit formed in a protrusion 45 at the end of the externally threaded member 16 B inserted in the case 13 . Due to its torsional deformation, the return spring 18 applies torque to the externally threaded member 16 B in the direction to push the pivot member 16 A out of the case 13 .
- the external thread 15 on the outer periphery of the externally threaded member 16 B and the internal thread 14 on the inner periphery of the case 13 are vertically symmetrical triangular threads.
- the bottom 17 of the case 13 may be integral with the case body as shown. But the bottom 17 of the case 13 may be formed separately from the case body and fixed to the bottom of case body.
- FIGS. 15 and 16 show a lash adjuster 51 according to the third embodiment of the present invention.
- the outer bottom surface 52 of the case 13 is in contact with the inner bottom surface 24 of the mounting hole 6 so as to support an axial load applied to the case 13 on the inner bottom surface 24 of the mounting hole 6 .
- a plurality of linear oil film expelling grooves 53 are formed on the outer bottom surface 52 of the case 13 .
- the oil film expelling grooves 53 are formed in the outer bottom surface 52 of the case 13 .
- the outer bottom surface 52 of the case 13 may be satin-finished. With this arrangement, compared to an arrangement in which the outer bottom surface 52 is flat and smooth, the outer bottom surface 52 has a higher friction coefficient, so that it is possible to ensure sufficient frictional resistance between the outer bottom surface 52 and the inner bottom surface 24 .
- the outer bottom surface 52 of the case 13 may be satin-finished by electric discharge machining or laser machining. But preferably, it is satin-finished by shot peening, because shot peening hardens the outer bottom surface 52 of the case 13 , thereby increasing its wear resistance, which in turn makes it possible to maintain frictional resistance between the outer bottom surface 52 and the inner bottom surface 24 over an extended period of time.
- the bottom 17 of the case 13 may have a tapered outer peripheral surface 55 having a downwardly decreasing diameter and engaged in a tapered inner peripheral surface 54 formed on the mounting hole 6 and having a downwardly decreasing diameter so as to support an axial load applied to the case 13 on the tapered inner peripheral surface 54 .
- a recess 56 may be formed in the outer bottom surface 52 of the case 13 except its peripheral edge so that only the peripheral edge of the outer bottom surface 52 of the case 13 contacts the inner bottom surface 24 of the mounting hole 6 .
- a recess may be formed in the inner bottom surface 24 of the mounting hole 6 except its peripheral edge so that only the peripheral edge of the inner bottom surface 24 of the mounting hole 6 contacts the outer inner bottom surface 52 of the case 13 .
- the bottom 17 of the case 13 may be press-fitted (i.e. fitted with an interference) into a small-diameter inner peripheral portion 57 formed on the mounting hole 6 and having a smaller diameter than the outer diameter of the bottom 17 of the case 13 .
- the case 13 Since the case 13 is fitted without interference at its portion above the bottom 17 , it is possible to minimize the possibility of deformation of the internal thread 14 when the case is press-fitted.
- a large-diameter outer peripheral portion (not shown) may be formed on the bottom 17 of the case 13 which is press-fitted in the mounting hole 6 . But with this arrangement, since the entire step of inserting the case 13 into the mounting hole 6 comprises press fitting, it is difficult to insert the case into the mounting hole.
- a sheet 58 made of rubber or an elastomer may be disposed between the outer bottom surface 52 of the case 13 and the inner bottom surface 24 of the mounting hole 6 so as to support an axial load applied to the case 13 on the sheet 58 .
- the frictional resistance between the outer bottom surface 52 and the inner bottom surface 24 is higher than when the outer bottom surface 52 is in direct contact with the inner bottom surface 24 , so that it is possible to ensure sufficient frictional resistance for preventing rotation of the case 13 .
- a seat 59 made of iron may be mounted in the mounting hole 6 so that the seat 59 forms the inner bottom surface 24 of the mounting hole 6 , and supports an axial load applied to the case 13 thereon.
- the inner bottom surface 24 of the mounting hole 6 is made of iron, even if the cylinder head is made of aluminum, the inner bottom surface 24 of the mounting hole 6 is less likely to become worn. This minimizes reduction with time in friction coefficient of the inner bottom surface 24 , and thus ensures sufficient frictional resistance between the bottom 17 of the case 13 and the inner surface of the mounting hole 6 .
- a cylindrical iron sleeve 61 having a bottom and formed with the amounting hole 6 may be press-fitted in a base hole 60 formed in the top surface of the cylinder head 2 so as to support an axial load applied to the case 13 on the sleeve 61 .
- the inner surface of the mounting hole 6 is made of iron, even if the cylinder head 2 is made of aluminum, the inner surface of the mounting hole 6 is less likely to become worn. This ensures sufficient frictional resistance between the bottom 17 of the case 13 and the inner surface of the mounting hole 6 . Also, there is no difference in shrinkage between the sleeve 61 and the case 13 , even when the ambient temperature rises, the case 13 remains strongly engaged in the mounting hole 6 .
Abstract
The object is to prevent rotation of the case when a load is applied to the adjusting screw that tends to push in the adjusting screw.
The lash adjuster includes a cylindrical case 13 having a bottom 17 and received in a mounting hole 6 formed in a top surface of a cylinder head 2, the case 13 having an internal thread 14 on an inner periphery thereof, an adjusting screw 16 having an external thread 15 on an outer periphery thereof which is in threaded engagement with the internal thread 14 of the case 13, and a return spring 18 disposed between the adjusting screw 16 and the bottom 17 of the case 13 and biasing the adjusting screw 16 in a direction to protrude upwardly from the case 13, the adjusting screw 16 having a protruding end 22 protruding from the case 13 and configured to pivotally support an arm 7 of a valve gear, wherein an anti-rotation protrusion 27 is provided on the bottom 17 of the case 13 which is fitted in a fitting port 26 formed in an inner bottom surface 24 of the mounting hole 6, thereby preventing rotation of the case 13.
Description
- This invention relates to a lash adjuster mounted in a valve gear for an engine.
- One known valve gear for moving a valve provided at an intake port or an exhaust port of an engine includes an arm pivotable about one end thereof and adapted to be pressed down at its mid-portion by a cam, thereby pressing down the valve stem at its other end.
- With this valve gear, while the engine is running, due to differences in thermal expansion between component parts of the valve gear, gaps between component parts of the valve gear may change, thereby producing noise or causing pressure leakage. When sliding parts of the valve gear become worn too, gaps between component parts of the valve gear change, thus producing noise or causing pressure leakage.
- In order to prevent such noise and pressure leakage, a typical valve gear includes a lash adjuster to eliminate gaps between component parts of the valve gear.
- Typically, such a lash adjuster comprises a cylindrical case having a bottom and received in a mounting hole formed in the top surface of the cylinder head, an adjusting screw having an external thread on the outer periphery thereof which is in threaded engagement with an internal thread formed on the inner periphery of the case, and a return spring biasing the adjusting screw in the direction to protrude upwardly from the case, thereby pivotally supporting the arm of the valve gear at the protruding end of the adjusting screw protruding from the case (
Patent documents 1 and 2). - In the arrangement of
Patent document 1, the return spring is a compression coil spring that applies an axial force to the adjusting screw that tends to push the adjusting screw out of the case. In the arrangement ofPatent document 2, the return spring is a torsion spring that applies torque to the adjusting screw that tends to push the adjusting screw out of the case. - With these lash adjusters, when the cam rotates and a load is applied to the adjusting screw that tends to push in the adjusting screw, the external thread of the adjusting screw is supported by the internal thread of the case, so that the adjusting screw is axially fixed in position.
- If the relative position between the arm and the cylinder head changes due e.g. to thermal expansion of the valve gear, according to the change in relative position, the adjusting screw axially moves in the case while rotating relative to the case, thereby absorbing the change in gaps between component parts of the valve gear.
- Patent document 1: JP Patent Publication 2005-273510A
Patent document 2: JP Patent Publication 64-34407A - With these adjusters, since the outer periphery of the case and the inner periphery of the mounting hole are both cylindrical surfaces, when a force in the rotational direction is applied to the case, the case rotates relative to the mounting hole. Particularly while the engine is running and the temperature of the valve gear is high, the case tends to easily rotate relative to the case, because in this state, a gap forms between fitting surfaces of the case and the mounting hole due to a difference in thermal expansion between the cylinder head and the case.
- Thus, with these lash adjusters, when the cam rotates and a load is applied to the adjusting screw that tends to push in the adjusting screw, the case may rotate relative to the mounting hole under the force that acts between the thread surfaces of the adjusting screw and the case. If the case rotates, the adjusting screw is pushed into the case, reducing the valve lift. Rotation of the case would also quicken wear of the mounting hole.
- An object of the present invention is to prevent rotation of the case when a load is applied to the adjusting screw that tends to push in the adjusting screw.
- In order to achieve this object, the lash adjuster is provided with an anti-rotation means for preventing rotation of the case.
- The anti-rotation means may comprise an anti-rotation protrusion provided on the bottom of the case, and a fitting port formed in an inner bottom surface of the mounting hole, in which the anti-rotation protrusion is fitted. With this arrangement, the case is prevented from rotating due to engagement of the anti-rotation protrusion in the fitting port.
- The anti-rotation protrusion may be a protrusion having a D-cut portion on an outer periphery thereof, a protrusion having two chamfers on an outer periphery thereof, a protrusion in the shape of a regular polygonal column, or a protrusion offset from an axis of the case.
- The fitting port may be one end of an air vent hole extending from the inner bottom surface of the mounting hole to outside. With this arrangement, when the lash adjuster is inserted into the mounting hole, air between the bottom of the case and the inner bottom surface of the mounting hole is discharged through the air vent hole, so that the interior of the mounting hole is kept at the atmospheric pressure, which prevents reaction force from acting on the bottom of the case. Thus, the lash adjuster can be mounted easily in the cylinder head. Since one end of the air vent passage is used as the fitting port, there is no need to form the fitting port separately from the air vent hole, which makes easier to form the cylinder head.
- A through hole may be formed to extend vertically through the bottom of the case, with a bottom end thereof open to a free end of the anti-rotation protrusion. With this arrangement, since engine oil flowing into the case through between the external thread of the adjusting screw and the internal thread of the case is discharged through the through hole and then the air vent hole, soot and other contaminants mixed into engine oil is less likely to get stuck between the external thread of the adjusting screw and the internal thread of the case, which makes the external thread and the internal thread less likely to become worn.
- The anti-rotation means may be a friction ensuring means for ensuring frictional resistance between the bottom of the case and the inner surface of the mounting hole, thereby preventing rotation of the case.
- The friction ensuring means comprises an oil film expelling groove formed in an outer bottom surface of the case. With this arrangement, engine oil present between the outer bottom surface of the case and the inner bottom surface of the mounting hole is released into the oil film expelling grooves. This prevents formation of oil film between the outer bottom surface of the case and the inner bottom surface of the mounting hole due to the squeezing effect, which in turn ensures sufficient frictional resistance between the outer bottom surface of the case and the inner bottom surface of the mounting hole.
- The friction ensuring means may comprise a satin-finished surface formed on the outer bottom surface of the case. With this arrangement, compared to an arrangement in which the outer bottom surface of the case is flat and smooth, the outer bottom surface of the case has a higher friction coefficient, so that it is possible to ensure sufficient frictional resistance between the outer bottom surface of the case and the inner bottom surface of the mounting hole. The outer bottom surface of the case may be satin-finished by electric discharge machining or laser machining. But preferably, it is satin-finished by shot peening, because shot peening hardens the outer bottom surface of the case, thereby increasing its wear resistance.
- The friction ensuring means may comprise a tapered outer peripheral surface formed on the bottom of the case and having a downwardly decreasing diameter, and a tapered inner peripheral surface formed on the mounting hole and having a downwardly decreasing diameter, with the tapered outer peripheral surface engaged in the tapered inner peripheral surface. With this arrangement, high surface pressure is produced between the tapered outer peripheral surface and the tapered inner peripheral surface due to the wedge effect, which ensures sufficient frictional resistance between the tapered outer peripheral surface and the tapered inner peripheral surface.
- The friction ensuring means may comprise a recess formed in the outer bottom surface of the case except its peripheral edge. With this arrangement, frictional resistance produced between the outer bottom surface of the case and the inner bottom surface of the mounting hole concentrates on the radially outer side, so that it is possible to ensure sufficient frictional resistance for preventing rotation of the case. Alternatively, a similar recess may be formed in the inner bottom surface of the mounting hole except its peripheral edge as the friction ensuring means.
- The friction ensuring means may comprise a small-diameter inner peripheral portion formed on the mounting hole, the bottom of the case being press-fitted in the small-diameter inner peripheral portion. With this arrangement, high surface pressure is produced between the bottom of the case and the small-diameter inner peripheral portion due to press fitting, which ensures sufficient frictional resistance between the bottom of the case and the inner surface of the mounting hole.
- The friction ensuring means may comprise a sheet made of rubber or an elastomer and disposed between an outer bottom surface of the case and the inner bottom surface of the mounting hole. With this arrangement, the frictional resistance between the outer bottom surface of the case and the inner bottom surface of the mounting hole is higher than when the outer bottom surface of the case is in direct contact with the inner bottom surface of the mounting hole, so that it is possible to ensure sufficient frictional resistance for preventing rotation of the case.
- The friction ensuring means may comprise a seat made of iron and forming the inner bottom surface of the mounting hole. With this arrangement, since the inner bottom surface of the mounting hole is less likely to become worn, even if the cylinder head is made of aluminum, it is possible to minimize reduction with time in friction coefficient of the inner bottom surface of the mounting hole, thus ensuring sufficient frictional resistance between the bottom of the case and the inner surface of the mounting hole.
- The friction ensuring means may comprise a sleeve made of iron and forming the mounting hole. With this arrangement, since the inner surface of the mounting hole is less likely to become worn, even if the cylinder head is made of aluminum, it is possible to minimize reduction with time in friction coefficient of the inner surface of the mounting hole, thus ensuring sufficient frictional resistance between the bottom of the case and the inner surface of the mounting hole.
- The return spring may be a compression coil spring that applies an axial force to the adjusting screw that tends to push the adjusting screw out of the case. Alternatively, the return spring may be a torsion spring that applies torque to the adjusting screw that tends to push the adjusting screw out of the case. The torsion spring may be one of a torsion coil spring, a spiral spring and a volute spring.
- The external thread and the internal thread are triangular threads, trapezoidal threads or serration-shaped threads.
- Since the lash adjuster according to this invention is provided with an anti-rotation means for preventing rotation of the case, the case is less likely to rotate when a load is applied to the adjusting screw that tends to push in the adjusting screw. This prevents reduction in the valve lift due to rotation of the case. The lash adjuster thus stably performs its function. Also, it is possible to prevent wear of the inner surface of the mounting hole.
-
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 ofFIG. 1 and its surrounding area. -
FIG. 3 is a sectional view taken along line III-III ofFIG. 2 . -
FIG. 4 is an enlarged view of a different anti-rotation protrusion from that ofFIG. 2 . -
FIG. 5 is a sectional view taken along line V-V ofFIG. 4 . -
FIG. 6 is an enlarged view of a still different anti-rotation protrusion from that ofFIG. 2 . -
FIG. 7 is a sectional view taken along line VII-VII ofFIG. 6 . -
FIG. 8 is an enlarged sectional view of a further different anti-rotation protrusion from that ofFIG. 2 . -
FIG. 9 is a sectional view taken along line IX-IX ofFIG. 8 . -
FIG. 10 is an enlarged sectional view of a lash adjuster according to a second embodiment of the present invention. -
FIG. 11 is an enlarged sectional view of a modification of the return spring shown inFIG. 10 . -
FIG. 12 is an enlarged sectional view of another modification of the return spring shown inFIG. 10 . -
FIG. 13 is a sectional view taken along line XIII-XIII ofFIG. 12 . -
FIG. 14 is an enlarged sectional view of still another modification of the return spring shown inFIG. 10 . -
FIG. 15 is an enlarged sectional view of a lash adjuster according to a third embodiment of the present invention. -
FIG. 16 is a sectional view taken along line XVI-XVI ofFIG. 15 . -
FIG. 17 is an enlarged sectional view of a modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 18 is an enlarged sectional view of another modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 19 is an enlarged sectional view of still another modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 20 is an enlarged sectional view of a further modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 21 is an enlarged sectional view of a still further modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 22 is an enlarged sectional view of still another modification of the means of ensuring friction shown inFIG. 15 . -
FIG. 23 is an enlarged sectional view of still another modification of the means of ensuring friction shown inFIG. 15 . -
- 1. Lash adjuster
- 2. Cylinder head
- 6. Mounting hole
- 7. Arm
- 13. Case
- 14. Internal thread
- 15. External thread
- 16. Adjusting screw
- 17. Bottom
- 18. Return spring
- 22. Protruding end
- 24. Inner bottom surface
- 25. Air vent hole
- 26. Fitting port
- 27. Anti-rotation protrusion
- 28. D-cut portion
- 30. Through hole
- 31. Two chamfers
- 32, 35, 37. Anti-rotation protrusion
- 41, 51. Lash adjuster
- 52. Outer bottom surface
- 53. Oil film expelling groove
- 54. Tapered inner peripheral surface
- 55. Tapered outer peripheral surface
- 56. Recess
- 57. Small-diameter inner peripheral portion
- 58. Sheet
- 59. Seat
- 61. Sleeve
-
FIG. 1 shows a valve gear including alash adjuster 1 according to a first embodiment of the present invention. This valve gear includes avalve 4 provided at anintake port 3 of acylinder head 2 of an engine, avalve stem 5 connected to thevalve 4, alash adjuster 1 mounted in a mountinghole 6 formed in the top surface of thecylinder head 2, and anarm 7 supported by thelash adjuster 1 so as to be pivotable about thelash adjuster 1. - The
valve stem 5 extends upwardly from thevalve 4 and slidably through thecylinder head 2. Anannular spring retainer 8 is fixed to the outer periphery of thevalve stem 5 at its upper portion. Avalve spring 9 is mounted between the bottom surface of thespring retainer 8 and the top surface of thecylinder head 2. Thevalve spring 9 biases thevalve stem 5 upwardly through thespring retainer 8, thereby seating thevalve 4 against avalve seat 10 by its biasing force. - The
arm 7 has one end thereof supported by thelash adjuster 1 and the other end in contact with the top end of thevalve stem 5. At its mid-portion, thearm 7 carries aroller 11 which is in contact with acam 12 provided over theroller 11. - As shown in
FIG. 2 , thelash adjuster 1 comprises acylindrical case 13 having a bottom and inserted in the mountinghole 6, an adjustingscrew 16 having anexternal thread 15 on its outer periphery at its lower portion which is threaded engagement with an internal thread formed on the inner periphery of thecase 13, and areturn spring 18 mounted between the adjustingscrew 16 and the bottom 17 of thecase 13. - The
external thread 15 and theinternal thread 14 each have a pressure flank that receives pressure when a load is applied that tends to push the adjustingscrew 16 into thecase 13. Thepressure flank 19 has a flank angle larger than theclearance flank 20 so that thethreads - The
return spring 18 is a compression coil spring having its bottom end supported by the bottom 17 of thecase 13 and applies, at its top end, an axial force to the adjustingscrew 16 through aspring seat 21 that tends to push the adjustingscrew 16 upwardly out of thecase 13. - As shown in
FIG. 1 , the adjustingscrew 16 has aprotruding end 22 protruding from thecase 13 and fitted in arecess 23 formed in the bottom surface of thearm 7 at its end, thus supporting thearm 7 so as to be pivotable about the protrudingend 22. Anair vent hole 25 is formed in thecylinder head 2 to extend from aninner bottom surface 24 of the mountinghole 6 to outside. When thelash adjuster 1 is inserted into the mountinghole 6, air between thecase 13 and theinner bottom surface 24 of the mountinghole 6 is discharged through theair vent hole 25. - As shown in
FIG. 2 , ananti-rotation protrusion 27 is formed on the bottom 17 of thecase 13 which is fitted in afitting port 26 formed in theinner bottom surface 24 of the mountinghole 6. Thefitting port 26 constitutes one end of theair vent hole 25. Theanti-rotation protrusion 27 has a D-cutportion 28 on its outer periphery which engages a D-cutportion 29 formed on the inner periphery of thefitting port 26, thereby rotationally fixing thecase 13 in position. The D-cutportion 28 is formed by cutting the outer periphery of theprotrusion 27 along a plane parallel to a plane including the axis of thecase 13. - The
case 13 is made of iron to ensure strength of theinternal thread 14. Thefitting port 26, which has the D-cutportion 29 on its inner periphery, and theair vent hole 25, which has thefitting port 26 at one end, can be formed when forming thecylinder head 2 by die-casting aluminum. - As shown in
FIG. 2 , a throughhole 30 extends vertically through the bottom 17 of thecase 13 with its bottom open to the bottom end surface of theanti-rotation protrusion 27. Thus, engine oil flowing into thecase 13 from its top end surface through the gap between theexternal thread 15 and theinternal thread 14 is discharged from thecase 13 through the throughhole 30 and then theair vent hole 25. - Now the operation of the
lash adjuster 1 is described. - While the engine is running, as the
cam 12 rotates and thecam lobe 12 a of thecam 12 presses thearm 7, thevalve 4 separates from thevalve seat 10, opening theintake port 3. At this time, a load is applied to the adjustingscrew 16 that tends to push in the adjusting screw. But since thepressure flank 19 of theexternal thread 15 is supported by thepressure flank 19 of theinternal thread 14 in this state, the adjustingscrew 16 is axially fixed in position. Also, torque is applied between the pressure flanks 19 of theexternal thread 15 and theinternal thread 14. But thecase 13 never rotates due to engagement between theanti-rotation protrusion 27 and thefitting port 26. - As the
cam 12 further rotates and thecam lobe 12 a moves past theroller 11, thevalve stem 5 rises under the biasing force of thevalve spring 9, so that thevalve 4 is seated on thevalve seat 10, closing theintake port 3. - Strictly speaking, when the
arm 7 is pressed down by thecam lobe 12 a of thecam 12, slight slip occurs between the pressure flanks 19 of theexternal thread 15 and theinternal thread 14, thus pushing in the adjustingscrew 16. But once thecam lobe 12 a moves past theroller 11 and the load that tends to push in the adjusting screw is removed, the adjustingscrew 16 returns to the original position under the load from thereturn spring 18 which tends to push out the adjusting screw. - While the engine is running, if the distance between the
cam 12 and thearm 7 increases due to thermal expansion differences between component parts of the valve gear such as thecylinder head 2,valve stem 5 andarm 7, the adjustingscrew 16 protrudes by a larger amount when thecam 12 further rotate after thecam lobe 12 a of thecam 12 presses down thearm 7 until the load is removed, than the amount by which the adjustingscrew 16 is pushed in when thearm 7 is pressed down by thecam lobe 12 a of thecam 12. As a result, every time thecam 12 rotates once, the adjustingscrew 16 protrudes gradually, thus preventing any gap between thebase circle 12 b of thecam 12 and theroller 11. - Conversely, if the contact surfaces of the
valve 4 and thevalve seat 10 become worn, the biasing force of thevalve spring 9 keeps acting on the adjustingscrew 16 even while thebase circle 12 b of thecam 12 faces theroller 11. Thus, the adjustingscrew 16 protrudes by a smaller amount when thecam 12 further rotates after thecam lobe 12 a of thecam 12 presses down thearm 7 until the load is removed, than the amount by which the adjustingscrew 16 is pushed in when thearm 7 is pressed down by thecam lobe 12 a of thecam 12. As a result, every time thecam 12 rotates once, the adjustingscrew 16 is pushed in gradually, allowing thevalve stem 5 to rise. This prevents any gap between the contact surfaces of thevalve 4 and thevalve seat 10. - With this lash
adjuster 1, since thecase 13 is rotationally fixed in position by the engagement between theanti-rotation protrusion 27 and thefitting port 26, when a load is applied to the adjustingscrew 16 that tends to push in the adjusting screw, thecase 13 never rotates. This prevents reduction in the valve lift due to rotation of thecase 13. The lash adjuster thus stably performs its function. Also, the inner surface of the mountinghole 6 never becomes worn. - With this lash
adjuster 1, when thelash adjuster 1 is inserted into the mountinghole 6, air between the bottom 17 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 is discharged through theair vent hole 25, so that the interior of the mountinghole 6 is kept at the atmospheric pressure, which prevents reaction force from acting on the bottom 17 of the case. Thus, the lash adjuster can be mounted easily in thecylinder head 2. Since one end of theair vent passage 25 is used as thefitting port 26, there is no need to form thefitting port 26 separately from theair vent hole 25, which makes easier to form thecylinder head 2. - With this lash
adjuster 1, since engine oil flowing into the case through between theexternal thread 15 of the adjustingscrew 16 and theinternal thread 14 of thecase 13 is discharged through the throughhole 30 and then theair vent hole 25, soot and other contaminants mixed into engine oil is less likely to get stuck between theexternal thread 15 of the adjustingscrew 16 and theinternal thread 14 of thecase 13, which makes theexternal thread 15 and theinternal thread 14 less likely to become worn. - In this embodiment, the
anti-rotation protrusion 27 provided on the bottom 17 of thecase 13 is theanti-rotation protrusion 27 having the D-cutportion 28 on the outer periphery. But instead of thisanti-rotation protrusion 27, as shown inFIGS. 4 and 5 , ananti-rotation protrusion 32 having twochamfers 31 may be used. By engaging the twochamfers 31 with twochamfers 34 formed on the inner periphery of thefitting port 33, it is possible to prevent rotation of thecase 13. With this arrangement, theanti-rotation protrusion 32 can be fitted in thefitting port 33 even when thecase 13 is rotated by 180°, thelash adjuster 1 can be more easily mounted in thecylinder head 2. The twochamfers 31 are two flat surfaces that are parallel to a plane including the axis of thecase 13. - Also, instead of the
anti-rotation protrusion 27, as shown inFIGS. 6 and 7 , ananti-rotation protrusion 35 in the shape of a regular polygonal column (such as a regular hexagonal column) 35 may be used. By engaging thisanti-rotation protrusion 35 in afitting port 36 in the shape of a regular polygonal column, it is possible to prevent rotation of thecase 13. With this arrangement, theanti-rotation protrusion 35 can be fitted in thefitting port 36 at a plurality of different angular positions of thecase 13, thelash adjuster 1 can be further easily mounted in thecylinder head 2. - As shown in
FIGS. 8 and 9 , theanti-rotation protrusion 27 may also be replaced by ananti-rotation protrusion 37 which is offset from the axis ofcase 13. Thisanti-rotation protrusion 37 is engaged in afitting port 38 which is offset from the axis of the mountinghole 6 to prevent rotation of thecase 13. -
FIG. 10 shows alash adjuster 41 according to the second embodiment of the present invention. As theanti-rotation protrusion 27 on the bottom 17 of thecase 13, this lashadjuster 41 includes thesame anti-rotation protrusion 27 as in the first embodiment, i.e. the one having the D-cutportion 28 on the outer periphery. Below, elements corresponding to those of the first embodiment are denoted by identical numerals and their description is omitted. - The adjusting
screw 16 comprises apivot member 16A axially slidably inserted in thecase 13, an externally threadedmember 16B supporting the end of thepivot member 16A inserted in thecase 13 and having theexternal thread 15 on the outer periphery, and adisc spring 16C disposed between thepivot member 16A and the externally threadedmember 16B. - The
return spring 18 is a torsion coil spring having its bottom end engaged in an engaginghole 42 formed in the bottom 17 of thecase 13, and its top end engaged in an engaginghole 43 formed in the externally threadedmember 16B. Due to its torsional deformation, thereturn spring 18 applies torque to the externally threadedmember 16B in the direction to push thepivot member 16A out of thecase 13. - On the bottom 17 of the
case 13, theanti-rotation protrusion 27 having the D-cutportion 28 on the outer periphery. Theanti-rotation protrusion 27 is engaged in thefitting port 26 formed in theinner bottom surface 24 of the mountinghole 6. - With this lash
adjuster 41, as with the first embodiment, since the rotation of thecase 13 is prevented by the engagement of theanti-rotation protrusion 27 in thefitting port 26, it is possible to prevent reduction in the valve lift due to rotation of thecase 13, so that the lash adjuster can stably perform its function. - With this lash
adjuster 41, when the engine stops at a high temperature and the engine cools down later, thus producing differences in shrinkage between component parts of the valve lifter, thedisc spring 16C between the externally threadedmember 16B and thepivot member 16A is compressed, thus absorbing the differences in shrinkage. Thus, when the engine is restarted, no gap is produced between thevalve 4 and thevalve seat 10 due to the shrinkage differences between component parts of the valve lifter, which prevents pressure leakage. - If the
return spring 18 is a torsion coil spring, thereturn spring 18 may be a cylindrically wound one as shown inFIG. 10 , or a conically wound one as shown inFIG. 11 . - As shown in
FIGS. 12 to 14 , thereturn spring 18 may be a torsion spring other than a torsion coil spring. - The
return spring 18 shown inFIGS. 12 and 13 is a volute spring formed by helically winding a thin sheet material. Thisreturn spring 18 has its radially outer end rotationally fixed to the bottom 17 of thecase 13, and its radially inner end fitted in a slit formed in aprotrusion 44 at the end of the externally threadedmember 16B inserted in thecase 13. Due to its torsional deformation, thereturn spring 18 applies torque to the externally threadedmember 16B in the direction to push thepivot member 16A out of thecase 13. Theexternal thread 15 on the outer periphery of the externally threadedmember 16B and theinternal thread 14 on the inner periphery of thecase 13 are vertically symmetrical trapezoidal threads. - The
return spring 18 shown inFIG. 14 is a spiral spring formed by spirally winding a thin sheet material. Thisreturn spring 18 has its radially outer end rotationally fixed to the bottom 17 of thecase 13, and its radially inner end fitted in a slit formed in aprotrusion 45 at the end of the externally threadedmember 16B inserted in thecase 13. Due to its torsional deformation, thereturn spring 18 applies torque to the externally threadedmember 16B in the direction to push thepivot member 16A out of thecase 13. Theexternal thread 15 on the outer periphery of the externally threadedmember 16B and theinternal thread 14 on the inner periphery of thecase 13 are vertically symmetrical triangular threads. - In the above embodiments, the bottom 17 of the
case 13 may be integral with the case body as shown. But the bottom 17 of thecase 13 may be formed separately from the case body and fixed to the bottom of case body. -
FIGS. 15 and 16 show alash adjuster 51 according to the third embodiment of the present invention. - In this embodiment, the
outer bottom surface 52 of thecase 13 is in contact with theinner bottom surface 24 of the mountinghole 6 so as to support an axial load applied to thecase 13 on theinner bottom surface 24 of the mountinghole 6. A plurality of linear oilfilm expelling grooves 53 are formed on theouter bottom surface 52 of thecase 13. - With this lash
adjuster 51, although torque is produced between the pressure flanks 19 of theexternal thread 15 and theinternal thread 14 when a load is applied to the adjustingscrew 16 that tends to push in the adjusting screw, the frictional resistance between theouter bottom surface 52 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 prevents rotation of thecase 13. - When a load is applied to the adjusting
screw 16 from thearm 7 that tends to push in the adjusting screw, engine oil present between theouter bottom surface 52 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 is released into the oilfilm expelling grooves 53. This prevents formation of oil film between theouter bottom surface 52 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 due to the squeezing effect, which in turn ensures sufficient frictional resistance between theouter bottom surface 52 and theinner bottom surface 24. - In this embodiment, in order to ensure sufficient frictional resistance between the bottom 17 of the
case 13 and the inner surface of the mountinghole 6, the oilfilm expelling grooves 53 are formed in theouter bottom surface 52 of thecase 13. But instead, as shown inFIG. 17 , theouter bottom surface 52 of thecase 13 may be satin-finished. With this arrangement, compared to an arrangement in which theouter bottom surface 52 is flat and smooth, theouter bottom surface 52 has a higher friction coefficient, so that it is possible to ensure sufficient frictional resistance between theouter bottom surface 52 and theinner bottom surface 24. - When a load is applied to the adjusting
screw 16 from thearm 7 that tends to push in the adjusting screw, engine oil present between theouter bottom surface 52 and theinner bottom surface 24 is released into recesses and protrusions of the satin-finished surface. This prevents formation of oil film between theouter bottom surface 52 and theinner bottom surface 24 due to the squeezing effect, which in turn ensures sufficient frictional resistance between theouter bottom surface 52 and theinner bottom surface 24. - The
outer bottom surface 52 of thecase 13 may be satin-finished by electric discharge machining or laser machining. But preferably, it is satin-finished by shot peening, because shot peening hardens theouter bottom surface 52 of thecase 13, thereby increasing its wear resistance, which in turn makes it possible to maintain frictional resistance between theouter bottom surface 52 and theinner bottom surface 24 over an extended period of time. - As shown in
FIG. 18 , the bottom 17 of thecase 13 may have a tapered outerperipheral surface 55 having a downwardly decreasing diameter and engaged in a tapered innerperipheral surface 54 formed on the mountinghole 6 and having a downwardly decreasing diameter so as to support an axial load applied to thecase 13 on the tapered innerperipheral surface 54. - With this arrangement, when a load is applied to the adjusting
screw 16 from thearm 7 that tends to push in the adjusting screw, high surface pressure is produced between the tapered outerperipheral surface 55 and the tapered innerperipheral surface 54 due to the wedge effect, which ensures sufficient frictional resistance between the tapered outerperipheral surface 55 and the tapered innerperipheral surface 54. - As shown in
FIG. 19 , arecess 56 may be formed in theouter bottom surface 52 of thecase 13 except its peripheral edge so that only the peripheral edge of theouter bottom surface 52 of thecase 13 contacts theinner bottom surface 24 of the mountinghole 6. - With this arrangement, when a load is applied to the adjusting
screw 16 from thearm 7 that tends to push in the adjustingscrew 16, frictional resistance produced between theouter bottom surface 52 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 concentrates on the radially outer side, so that it is possible to ensure sufficient frictional resistance for preventing rotation of thecase 13. - Similarly, a recess (not shown) may be formed in the
inner bottom surface 24 of the mountinghole 6 except its peripheral edge so that only the peripheral edge of theinner bottom surface 24 of the mountinghole 6 contacts the outerinner bottom surface 52 of thecase 13. With this arrangement too, frictional resistance produced between theouter bottom surface 52 of the case and theinner bottom surface 24 of the mountinghole 6 concentrates on the radially outer side, so that it is possible to ensure sufficient frictional resistance for preventing rotation of thecase 13. - As shown in
FIG. 20 , the bottom 17 of thecase 13 may be press-fitted (i.e. fitted with an interference) into a small-diameter innerperipheral portion 57 formed on the mountinghole 6 and having a smaller diameter than the outer diameter of the bottom 17 of thecase 13. - With this arrangement, high surface pressure is produced between the bottom 17 and the small-diameter inner
peripheral portion 57 due to press fitting, which ensures sufficient frictional resistance between the bottom 17 of thecase 13 and the inner surface of the mountinghole 6. - Since the
case 13 is fitted without interference at its portion above the bottom 17, it is possible to minimize the possibility of deformation of theinternal thread 14 when the case is press-fitted. In order to minimize deformation of theinternal thread 14 when the case is press-fitted, a large-diameter outer peripheral portion (not shown) may be formed on the bottom 17 of thecase 13 which is press-fitted in the mountinghole 6. But with this arrangement, since the entire step of inserting thecase 13 into the mountinghole 6 comprises press fitting, it is difficult to insert the case into the mounting hole. On the other hand, by inserting the bottom 17 of thecase 13 into the small-diameter innerperipheral portion 57, only the last stage of the step of inserting thecase 17 into the mountinghole 6 is press fitting, so that the case can be more easily inserted into the mounting hole. - As shown in
FIG. 21 , asheet 58 made of rubber or an elastomer may be disposed between theouter bottom surface 52 of thecase 13 and theinner bottom surface 24 of the mountinghole 6 so as to support an axial load applied to thecase 13 on thesheet 58. - With this arrangement, the frictional resistance between the
outer bottom surface 52 and theinner bottom surface 24 is higher than when theouter bottom surface 52 is in direct contact with theinner bottom surface 24, so that it is possible to ensure sufficient frictional resistance for preventing rotation of thecase 13. - As shown in
FIG. 22 , aseat 59 made of iron may be mounted in the mountinghole 6 so that theseat 59 forms theinner bottom surface 24 of the mountinghole 6, and supports an axial load applied to thecase 13 thereon. - With this arrangement, since the
inner bottom surface 24 of the mountinghole 6 is made of iron, even if the cylinder head is made of aluminum, theinner bottom surface 24 of the mountinghole 6 is less likely to become worn. This minimizes reduction with time in friction coefficient of theinner bottom surface 24, and thus ensures sufficient frictional resistance between the bottom 17 of thecase 13 and the inner surface of the mountinghole 6. - As shown in
FIG. 23 , acylindrical iron sleeve 61 having a bottom and formed with the amountinghole 6 may be press-fitted in abase hole 60 formed in the top surface of thecylinder head 2 so as to support an axial load applied to thecase 13 on thesleeve 61. - With this arrangement, since the inner surface of the mounting
hole 6 is made of iron, even if thecylinder head 2 is made of aluminum, the inner surface of the mountinghole 6 is less likely to become worn. This ensures sufficient frictional resistance between the bottom 17 of thecase 13 and the inner surface of the mountinghole 6. Also, there is no difference in shrinkage between thesleeve 61 and thecase 13, even when the ambient temperature rises, thecase 13 remains strongly engaged in the mountinghole 6.
Claims (22)
1. A lash adjuster comprising a cylindrical case (13) having a bottom (17) and received in a mounting hole (6) formed in a top surface of a cylinder head (2), said case (13) having an internal thread (14) on an inner periphery thereof, an adjusting screw (16) having an external thread (15) on an outer periphery thereof which is in threaded engagement with the internal thread (14) of the case (13), and a return spring (18) disposed between the adjusting screw (16) and the bottom (17) of the case (13) and biasing the adjusting screw (16) in a direction to protrude upwardly from the case (13), said adjusting screw (16) having a protruding end (22) protruding from the case (13) and configured to pivotally support an arm (7) of a valve gear, characterized in that the lash adjuster further comprises an anti-rotation part arranged to prevent rotation of the case (13).
2. The lash adjuster of claim 1 wherein said anti-rotation part comprises an anti-rotation protrusion (27) provided on the bottom (17) of the case (13), and a fitting port (26) formed in an inner bottom surface (24) of the mounting hole (6), said anti-rotation protrusion (27) being fitted in the fitting port (26).
3. The lash adjuster of claim 2 wherein said anti-rotation protrusion is a protrusion (27) having a D-cut portion (28) on an outer periphery thereof.
4. The lash adjuster of claim 2 wherein said anti-rotation protrusion is a protrusion (32) having two chamfers (31) on an outer periphery thereof.
5. The lash adjuster of claim 2 wherein said anti-rotation protrusion is a protrusion (35) in the shape of a regular polygonal column.
6. The lash adjuster of claim 2 wherein said anti-rotation protrusion is a protrusion (37) offset from an axis of the case (13).
7. The lash adjuster of claim 2 wherein said fitting port (26) is one end of an air vent hole (25) extending from the inner bottom surface (24) of the mounting hole (6) to outside.
8. The lash adjuster of claim 7 wherein a through hole (30) extends vertically through the bottom (17) of the case(13), with a bottom end thereof open to a free end of the anti-rotation protrusion (27).
9. The lash adjuster of claim 1 wherein said anti-rotation part is a friction ensuring part configured to ensure frictional resistance between the bottom (17) of the case (13) and the inner surface of the mounting hole (6), thereby preventing rotation of the case (13).
10. The lash adjuster of claim 9 wherein said friction ensuring part comprises an oil film expelling groove (53) formed in an outer bottom surface (52) of the case (13).
11. The lash adjuster of claim 9 wherein said friction ensuring part comprises a satin-finished surface formed on an outer bottom surface (52) of the case (13).
12. The lash adjuster of claim 11 wherein said satin-finished surface is formed by shot peening.
13. The lash adjuster of claim 9 wherein said friction ensuring part comprises a tapered outer peripheral surface (55) formed on the bottom (17) of the case (13) and having a downwardly decreasing diameter, and a tapered inner peripheral surface (54) formed on the mounting hole (6) and having a downwardly decreasing diameter, said tapered outer peripheral surface (55) being engaged in the tapered inner peripheral surface (54).
14. The lash adjuster of claim 9 wherein said friction ensuring part comprises a recess (56) formed in an outer bottom surface (52) of the case (13) except its peripheral edge, or a recess formed in an inner bottom surface (24) of the mounting hole (6) except its peripheral edge.
15. The lash adjuster of claim 9 wherein said friction ensuring part comprises a small-diameter inner peripheral portion (57) formed on the mounting hole (6), said bottom (17) of the case (13) being press-fitted in the small-diameter inner peripheral portion (57).
16. The lash adjuster of claim 9 wherein said friction ensuring part comprises a sheet (58) made of rubber or an elastomer and disposed between an outer bottom surface (52) of the case (13) and an inner bottom surface (24) of the mounting hole (6).
17. The lash adjuster of claim 9 wherein said friction ensuring part comprises a seat (59) made of iron and forming an inner bottom surface (24) of the mounting hole (6).
18. The lash adjuster of claim 9 wherein said friction ensuring part comprises a sleeve (61) made of iron and forming the mounting hole (6).
19. The lash adjuster of claim 1 wherein said return spring (18) is a compression coil spring that applies an axial force to the adjusting screw (16) that tends to push the adjusting screw (16) out of the case (13).
20. The lash adjuster of claim 1 wherein said return spring (18) is a torsion spring that applies torque to the adjusting screw (16) that tends to push the adjusting screw (16) out of the case (13).
21. The lash adjuster of claim 20 wherein said torsion spring is one of a torsion coil spring, a spiral spring and a volute spring.
22. The lash adjuster of claim 1 wherein said external thread (15) and the internal thread (14) are triangular threads, trapezoidal threads or serration-shaped threads.
Applications Claiming Priority (9)
Application Number | Priority Date | Filing Date | Title |
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JP2008-0759502008 | 2008-03-24 | ||
JP2008075950 | 2008-03-24 | ||
JP2008-1109912008 | 2008-04-22 | ||
JP2008110991 | 2008-04-22 | ||
JP2008257362A JP2009281376A (en) | 2008-04-22 | 2008-10-02 | Lash adjuster |
JP2008257342A JP2009257305A (en) | 2008-03-24 | 2008-10-02 | Lash adjuster |
JP2008-2573422008 | 2008-10-02 | ||
JP2008-2573622008 | 2008-10-02 | ||
PCT/JP2009/055002 WO2009119362A1 (en) | 2008-03-24 | 2009-03-16 | Lash adjuster |
Publications (1)
Publication Number | Publication Date |
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US20110036314A1 true US20110036314A1 (en) | 2011-02-17 |
Family
ID=43587836
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/921,587 Abandoned US20110036314A1 (en) | 2008-03-24 | 2009-03-16 | Lash adjuster |
Country Status (2)
Country | Link |
---|---|
US (1) | US20110036314A1 (en) |
DE (1) | DE112009000693T5 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100263613A1 (en) * | 2007-12-07 | 2010-10-21 | Makoto Yasui | Lash adjuster |
US20100263614A1 (en) * | 2007-12-25 | 2010-10-21 | Makoto Yasui | Lash adjuster |
US20140190450A1 (en) * | 2013-01-10 | 2014-07-10 | Suzuki Motor Corporation | Cylinder head of engine |
US20150007790A1 (en) * | 2013-07-04 | 2015-01-08 | Mttek Co., Ltd. | Variable-angle vortex generator |
US20150068485A1 (en) * | 2014-11-18 | 2015-03-12 | Caterpillar Inc. | Cylinder head having wear resistant laser peened portions |
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US3584611A (en) * | 1969-07-25 | 1971-06-15 | Lloyd E Miller Jr | Temperature compensating valve lifter for internal combustion engine |
US3791355A (en) * | 1972-02-24 | 1974-02-12 | Johnson Products Inc | Mechanical lash adjuster for overhead cam engines |
US4463714A (en) * | 1981-10-08 | 1984-08-07 | Nissan Motor Company, Limited | Hydraulic lifter |
US4981117A (en) * | 1987-12-19 | 1991-01-01 | Gkn Technology Limited | Automatic clearance adjuster |
US20030075131A1 (en) * | 2000-02-02 | 2003-04-24 | Gill Peter John | Automatic valve clearance adjuster |
US6655333B2 (en) * | 2000-12-11 | 2003-12-02 | Ina Walzlager Schaeffler Ohg | Valve train of an internal combustion engine comprising one or more switchable support elements |
US20040182340A1 (en) * | 2003-03-19 | 2004-09-23 | Eaton Corporation | Dual valve lift and valve deactivation |
US20040211380A1 (en) * | 2002-06-12 | 2004-10-28 | Eiji Maeno | Lash adjuster for valve actuator |
JP2006132426A (en) * | 2004-11-05 | 2006-05-25 | Ntn Corp | Arm type valve gear |
US7146953B2 (en) * | 2000-11-14 | 2006-12-12 | Fev Motorentechnik Gmbh | Mechanical valve play compensation element for a valve drive on a piston combustion engine |
US20080083382A1 (en) * | 2006-10-06 | 2008-04-10 | Ford Global Technologies, Llc | Pushrod engine with multiple independent lash adjusters for each pushrod |
US20100126453A1 (en) * | 2007-05-14 | 2010-05-27 | Eiji Maeno | Lash adjuster for swing arm type valve gear |
US7954468B2 (en) * | 2006-12-28 | 2011-06-07 | Nittan Valve Co., Ltd. | Mechanical adjuster |
US8136493B2 (en) * | 2007-04-18 | 2012-03-20 | Ntn Corporation | Lash adjuster |
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JPS6434407A (en) | 1987-07-30 | 1989-02-03 | Toray Industries | Porous membrane of polytetrafluoroethylene-base resin and production thereof |
JP4204501B2 (en) | 2004-03-24 | 2009-01-07 | Ntn株式会社 | Automatic valve clearance adjustment device |
-
2009
- 2009-03-16 DE DE112009000693T patent/DE112009000693T5/en not_active Withdrawn
- 2009-03-16 US US12/921,587 patent/US20110036314A1/en not_active Abandoned
Patent Citations (15)
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---|---|---|---|---|
US3584611A (en) * | 1969-07-25 | 1971-06-15 | Lloyd E Miller Jr | Temperature compensating valve lifter for internal combustion engine |
US3791355A (en) * | 1972-02-24 | 1974-02-12 | Johnson Products Inc | Mechanical lash adjuster for overhead cam engines |
US4463714A (en) * | 1981-10-08 | 1984-08-07 | Nissan Motor Company, Limited | Hydraulic lifter |
US4981117A (en) * | 1987-12-19 | 1991-01-01 | Gkn Technology Limited | Automatic clearance adjuster |
US20030075131A1 (en) * | 2000-02-02 | 2003-04-24 | Gill Peter John | Automatic valve clearance adjuster |
US7146953B2 (en) * | 2000-11-14 | 2006-12-12 | Fev Motorentechnik Gmbh | Mechanical valve play compensation element for a valve drive on a piston combustion engine |
US6655333B2 (en) * | 2000-12-11 | 2003-12-02 | Ina Walzlager Schaeffler Ohg | Valve train of an internal combustion engine comprising one or more switchable support elements |
US20040211380A1 (en) * | 2002-06-12 | 2004-10-28 | Eiji Maeno | Lash adjuster for valve actuator |
US20040182340A1 (en) * | 2003-03-19 | 2004-09-23 | Eaton Corporation | Dual valve lift and valve deactivation |
JP2006132426A (en) * | 2004-11-05 | 2006-05-25 | Ntn Corp | Arm type valve gear |
US20080083382A1 (en) * | 2006-10-06 | 2008-04-10 | Ford Global Technologies, Llc | Pushrod engine with multiple independent lash adjusters for each pushrod |
US20080283011A1 (en) * | 2006-10-06 | 2008-11-20 | Ford Global Technologies, Llc | Pushrod engine with multiple independent lash adjusters for each pushrod |
US7954468B2 (en) * | 2006-12-28 | 2011-06-07 | Nittan Valve Co., Ltd. | Mechanical adjuster |
US8136493B2 (en) * | 2007-04-18 | 2012-03-20 | Ntn Corporation | Lash adjuster |
US20100126453A1 (en) * | 2007-05-14 | 2010-05-27 | Eiji Maeno | Lash adjuster for swing arm type valve gear |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100263613A1 (en) * | 2007-12-07 | 2010-10-21 | Makoto Yasui | Lash adjuster |
US20100263614A1 (en) * | 2007-12-25 | 2010-10-21 | Makoto Yasui | Lash adjuster |
US20140190450A1 (en) * | 2013-01-10 | 2014-07-10 | Suzuki Motor Corporation | Cylinder head of engine |
US9709000B2 (en) * | 2013-01-10 | 2017-07-18 | Suzuki Motor Corporation | Cylinder head of engine |
US20150007790A1 (en) * | 2013-07-04 | 2015-01-08 | Mttek Co., Ltd. | Variable-angle vortex generator |
US8960146B2 (en) * | 2013-07-04 | 2015-02-24 | Mttek Co., Ltd. | Variable-angle vortex generator |
US20150068485A1 (en) * | 2014-11-18 | 2015-03-12 | Caterpillar Inc. | Cylinder head having wear resistant laser peened portions |
Also Published As
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DE112009000693T5 (en) | 2011-03-24 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: NTN CORPORATION, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YASUI, MAKOTO;MAENO, EIJI;YAMAGUCHI, KATSUHISA;SIGNING DATES FROM 20100817 TO 20100819;REEL/FRAME:024959/0277 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |