US20060027200A1 - Valve lifter and forming and processing method therefor - Google Patents
Valve lifter and forming and processing method therefor Download PDFInfo
- Publication number
- US20060027200A1 US20060027200A1 US11/185,810 US18581005A US2006027200A1 US 20060027200 A1 US20060027200 A1 US 20060027200A1 US 18581005 A US18581005 A US 18581005A US 2006027200 A1 US2006027200 A1 US 2006027200A1
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- United States
- Prior art keywords
- section
- valve lifter
- hole
- forming
- diameter
- Prior art date
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- Abandoned
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- 238000003672 processing method Methods 0.000 title claims abstract description 20
- 238000004381 surface treatment Methods 0.000 claims abstract description 10
- 239000010687 lubricating oil Substances 0.000 claims description 36
- 239000002335 surface treatment layer Substances 0.000 claims description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 17
- 229910052799 carbon Inorganic materials 0.000 claims description 17
- 230000002093 peripheral effect Effects 0.000 claims description 15
- 239000003921 oil Substances 0.000 claims description 13
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 238000005498 polishing Methods 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 238000010273 cold forging Methods 0.000 claims description 3
- 229910000838 Al alloy Inorganic materials 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000003754 machining Methods 0.000 description 9
- 238000002485 combustion reaction Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000003746 surface roughness Effects 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 229910000968 Chilled casting Inorganic materials 0.000 description 1
- 239000006061 abrasive grain Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000005422 blasting Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000005256 carbonitriding Methods 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000011859 microparticle Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 208000016261 weight loss Diseases 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Images
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
- F01L1/02—Valve drive
- F01L1/04—Valve drive by means of cams, camshafts, cam discs, eccentrics or the like
-
- 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
- F01L1/14—Tappets; Push rods
- F01L1/143—Tappets; Push rods for use with overhead camshafts
-
- 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
- F01L1/14—Tappets; Push rods
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01M—LUBRICATING OF MACHINES OR ENGINES IN GENERAL; LUBRICATING INTERNAL COMBUSTION ENGINES; CRANKCASE VENTILATING
- F01M1/00—Pressure lubrication
- F01M1/06—Lubricating systems characterised by the provision therein of crankshafts or connecting rods with lubricant passageways, e.g. bores
Definitions
- This invention relates to improvements in a valve lifter in an internal combustion engine, and in a forming and processing method of the valve lifter, and more particularly to improvements in a surface treatment method for a top surface of a crown section or a shim of the valve lifter with which a cam formed to a camshaft is in slidable contact.
- a high frictional resistance is produced between a boss section of a bottom surface of a crown section and a stem end of an intake valve during engine operation.
- a technique as disclosed in Japanese Patent Provisional Publication No. 2001-342810 is proposed, in which a lubricating oil supply hole is formed piercing the crown section of the valve lifter in order to positively supply lubricating oil between the boss section and the stem end.
- the lubricating oil supply hole or the air hole is formed on an outer peripheral side of the top surface of the crown section or the shim, a cam formed to a camshaft is in slidable contact with an edge defining the lubricating oil supply hole or the air hole because the cam is in slidable contact with the generally whole top surface in a diametrical direction of the crown section or the shim in order to ensure a high lift amount of the intake valve.
- a bearing pressure applied to the edge defining the lubricating oil supply hole or the air hole becomes high when the cam is in slidable contact with the edge.
- a contrivance to lower the bearing pressure is performed in such a manner that the edge defining the upper end of lubricating oil supply hole or the air hole is chamfered to form a diameter-increasing or flared section.
- a surface treatment is carried out on the top surface of the crown section or the shim so that a surface treatment layer high in hardness is formed in order to lower a sliding frictional resistance and to ensure a wear resistance.
- the surface treatment layer on the diameter-increasing section is unavoidably thin-walled since the diameter-increasing section is formed along the edge defining the opening of the upper end of the lubricating oil supply hole or the air hole after the surface treatment is carried out.
- an object of the present invention to provide improved valve lifter and forming and processing method therefor which can effectively overcome drawbacks encountered in conventional valve lifters and forming and processing methods therefor.
- An aspect of the present invention resides in a forming and processing method for a valve lifter which method comprises the steps of: (a) forming a hole in the valve lifter at a site where a cam is slidably contacted with; (b) forming a diameter-increasing section along an edge of the valve lifter, the edge defining a part of the hole and being located on a side with which the cam is slidably contacted; and (c) carrying out a surface treatment to whole of a surface of the valve lifter which surface is on the side with which the cam is slidably contacted.
- a valve lifter which comprises a crown section formed with a hole at a site where a cam is slidably contacted and having an edge of the valve lifter.
- the edge defines a part of the hole.
- a diameter-increasing section is formed along the edge.
- a skirt section is formed integral with an outer peripheral edge of the crown section.
- a surface treatment layer is formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
- a further aspect of the present invention resides in a valve lifter which comprises a crown section formed with a circular recess and an oil hole formed to communicate with the recess so as to pierce the crown section.
- a skirt section is formed integral with an outer peripheral edge of the crown section.
- a shim is accommodated in the recess and formed with a hole piercing the shim.
- a diameter-increasing section is formed along an edge defining a part of the hole.
- a surface treatment layer is formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
- FIG. 1 is a fragmentary cross-sectional view of an essential part of a first embodiment of a valve lifter according to the present invention
- FIG. 2 is a longitudinal sectional view of the valve lifter of FIG. 1 ;
- FIG. 3 is a top plan view of the valve lifter of FIG. 1 ;
- FIG. 4 is a fragmentary cross-sectional view of the essential part of a valve lifter used for an endurance test for the comparison purpose;
- FIG. 5 is a cross-sectional view of a valve operating system of an internal combustion engine to which the first embodiment of the valve lifter is applied;
- FIG. 6 is a fragmentary cross-sectional view of the essential part of a second embodiment of the valve lifter according to the present invention.
- FIG. 7A is a longitudinal sectional view of a valve lifter and a cam under a condition in which they are contacted with each other;
- FIG. 7B is a cross-sectional view taken on line A-A of FIG. 7A ;
- FIG. 8 is a longitudinal sectional view of a fourth embodiment of the valve lifter according to the present invention.
- FIG. 9 is a fragmentary enlarged view of a part around a diameter-increasing section of a valve lifter according to a conventional technique, showing a peeling phenomenon of a diamond-like carbon layer at the diameter-increasing section due to a conventional forming process.
- valve lifter 7 , 8 form part of a valve operating system of an internal combustion engine for an automotive vehicle.
- the valve operating system is shown in FIG. 5 and includes intake and exhaust valves 2 , 3 which open or close the open end portions of intake port 1 a and exhaust port 1 b which are communicated with a combustion chamber (not identified) and formed in cylinder head 1 .
- Camshafts 4 , 4 provided on intake and exhaust sides are rotatably supported through bearings (not shown) to upper end sections of cylinder head 1 .
- Driving cams 5 , 6 are formed integral with the outer peripheral surfaces of camshafts 4 , 4 .
- Valve lifters 7 , 8 are sliding members which convert rotary motion of driving cams 5 , 6 into reciprocating motion and then transfer the reciprocating motion to intake and exhaust valves 2 , 3 .
- Valve lifters 7 , 8 are slidably held in the inner walls of small diameter bores 1 c , 1 d formed in cylinder head 1 , respectively.
- Intake and exhaust valves 2 , 3 are biased in a direction to close the open end portions of intake port 1 a and exhaust port 1 b respectively by valve springs 12 , 13 each of which is elastically disposed between each spring retainer 11 provided to upper end section of each valve stem and the bottom surface of each small diameter bore 1 c , 1 d .
- Intake and exhaust valves 2 , 3 are slidably supported respectively through cylindrical valve guides 9 , 10 fixed to cylinder head 1 .
- Rotational driving force of the engine is transferred to camshafts 4 , 4 on the intake and exhaust sides from a crankshaft through a driving sprocket and a driven sprocket which are connected by a timing chain, though not shown. That is, driving cams 5 , 6 are rotated together with camshafts 4 , 4 , thereby pushing or operating intake and exhaust valves 2 , 3 in a direction to open the open end portions of intake port 1 a and exhaust port 1 b.
- Each of driving cams 5 , 6 is formed in a teardrop shape and formed of chilled casting or the like.
- Cam surfaces 5 a , 6 a formed respectively to the outer peripheral surfaces of driving cams 5 , 6 slide on crown surfaces or upper surfaces 14 a of crown sections 14 of valve lifters 7 , 8 .
- cam surfaces 5 a , 6 a are subjected to super-finishing by polishing, and thereafter subjected to a shot blasting treatment so as to have a certain surface roughness providing a smooth surface.
- valve lifter 7 is formed of an iron-based metallic material as a one-piece member and includes as the main parts crown section 14 and cylindrical skirt section 15 .
- Crown section 14 is a circular upper wall section.
- Cylindrical skirt section 15 is formed integral with an outer peripheral edge of crown section 14 .
- Crown section 14 has crown surface 14 a which is the top surface of crown section 14 and gently spherical or round. In other words, crown surface 14 a is a part of the surface of a large sphere. Crown section 14 includes boss section 14 b which is contacted with a stem end of intake valve 2 and formed in the generally cylindrical shape. Boss section 14 b is located at the central portion of a bottom surface of crown section 14 .
- lubricating oil supply hole 16 is formed at a certain position in a circumferential direction of the valve lifter and on an outer peripheral side of crown section 14 in a manner to pierce crown section 14 .
- diameter-increasing or flared section 16 a is formed at an annular portion or edge (of crown section 14 ) defining the upper open end portion of lubricating oil supply hole 16 .
- surface treatment layer 17 high in hardness is formed on the whole of crown surface 14 a by using a diamond-like carbon treatment.
- a lapping treatment is made on surface treatment layer 17 after the diamond-like carbon treatment.
- valve lifter 7 a forming and processing method for the whole of valve lifter 7 will be discussed.
- an iron-based metal as a base material is formed into a basic shape of valve lifter 7 by cold forging, the basic shape being the shape of a cylinder having a closed bottom.
- lubricating oil supply hole 16 may be formed during the above-mentioned cold forging.
- valve lifter 7 is subjected to a heat treatment such as carburizing, carbonitriding, nitriding or the like. Thereafter, polishing is made on the outer peripheral surfaces of boss section 14 b and skirt section 15 so as to adjust the outer diameters of boss section 14 b and skirt section 15 to the outer diameter of the stem end and the inner diameter of bore 1 c , 1 d in order to ensure a sliding accuracy.
- a heat treatment such as carburizing, carbonitriding, nitriding or the like.
- crown surface 14 a is subjected to super-finishing so as to have a surface roughness (according to Japanese Industrial Standard JIS B0601) of about 0.1 ⁇ m.
- outer peripheral side of crown surface 14 a is subjected to so-called R-machining (rounding machining) by lapping, barreling, shotblasting and the like so as to have the surface roughness of about 0.2 ⁇ m. It will be understood that this surface treatment may be carried out during the above-mentioned polishing.
- diameter-increasing or flared section 16 a is formed on the annular portion or edge defining the upper open end portion of lubricating oil supply hole 16 , in such a manner that its round surface (in section or a vertical plane containing the axis of lubricating oil supply hole 16 ) has a radius of curvature R within a range of from about 0.05 to 0.2 mm. Additionally, the surface of diameter-increasing section 16 a is subjected to finishing machining so as to have the surface roughness of about 0.2 ⁇ m. This diameter-increasing section 16 a may be formed during the above polishing.
- valve lifter 7 is rinsed and then put into an oven for diamond-like carbon treatment.
- the diamond-like carbon treatment is carried out on the whole of crown surface 14 a so as to form surface treatment layer or diamond-like carbon layer 17 high in hardness on the whole of crown surface 14 a .
- This diamond-like carbon treatment is carried out not only on the whole of crown surface 14 a but also on the inside surface of lubricating oil supply hole 16 through the surface of diameter-increasing section 16 a of lubricating oil supply hole 16 .
- surface treatment layer 17 is formed on the whole of crown surface 14 a by carrying out the diamond-like carbon treatment after diameter-increasing section 16 a having the round surface is formed at the annular portion or edge defining the upper open end portion of lubricating oil supply hole 16 , surface treatment layer 17 formed on diameter-increasing section 16 a is prevented from decreasing in thickness. As a result, surface treatment layer 17 on diameter-increasing section 16 a is prevented from peeling-off even if sliding movement of cam surface 5 a is continued, so that a wear resistance of diameter-increasing section 16 a is improved.
- the minute recesses are so formed that its total area becomes about 5 to 30% of the whole area of crown surface 14 a by lapping after surface treatment layer 17 high in hardness is formed on crown surface 14 a by the diamond-like carbon treatment.
- a frictional resistance between crown surface 14 a and cam surface 5 a can be reduced.
- a sufficient amount of lubricating oil is always retained in a plurality of minute recesses so that an oil film can be formed between crown surface 14 a and cam surface 5 a when cam surface 5 a is slid on valve lifter 7 . Consequently, the wear resistance of valve lifter 7 is improved, while the frictional resistance between crown surface 14 a of valve lifter 7 and cam surface 5 a of cam 5 can be further lowered.
- FIG. 6 illustrates a second embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that diameter-increasing section 16 a at the annular portion or edge defining the upper open end portion of lubricating oil supply hole 16 is formed tapered or having a frustoconical surface in place of the round surface.
- tapered diameter-increasing section 16 a of the second embodiment is shaped into a reversed frustum of a cone having a generally flat surface which is straight in section.
- the diamond-like carbon treatment is carried out on crown surface 14 a and the surface of the above tapered diameter-increasing section 16 a after tapered diameter-increasing section 16 a is formed.
- diameter-increasing section 16 a is formed tapered or frustoconical, its forming and machining is facilitated as compared with those in the first embodiment in which diameter-increasing section 16 a is formed round in section.
- FIGS. 7A and 7B illustrate a third embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that crown surface 14 a of crown section 14 of valve lifter 7 is spherically shaped having a large radius of curvature in section. On this spherical crown surface 14 a , surface treatment layer 17 high in hardness is formed by the diamond-like carbon treatment.
- cam surface 5 a is contacted with surface treatment layer 17 in the condition of forming a contact point P, a sliding resistance between them is lowered.
- the normal at the point P can approach an axis X by adjusting an inclination of cam 5 or inclination of the axis of camshaft 4 as shown in FIG. 7B , a sliding resistance between valve lifter 7 and the inner wall of small diameter bores 1 c can be lowered.
- FIG. 8 illustrates a fourth embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that the main body of valve lifter 7 is formed of an aluminum alloy for weight-reduction, in which circular recess 19 is formed at the upper surface of crown section 14 , disk-shaped shim 20 being accommodated in circular recess 19 .
- Oil groove 19 a is annularly formed at a certain position of the outer peripheral side of circular recess 19 .
- oil hole 19 b through which lubricating oil flows is formed at a certain position in a circumferential direction of oil groove 19 a so as to communicate with oil groove 19 a and pierce the upper wall of crown section 14 .
- Shim 20 is formed of an iron-based metal.
- Lubricating oil supply hole 16 is formed at a certain position of shim 20 which position corresponds to oil hole 19 b communicating with oil groove 19 a so as to pierce shim 20 .
- diameter-increasing section 16 a having the round surface is formed at the annular portion or edge defining the upper open end portion of lubricating oil supply hole 16 .
- surface treatment layer 17 is formed by the diamond-like carbon treatment.
- This surface treatment layer 17 is formed by the diamond-like carbon treatment after lubricating oil supply hole 16 and diameter-increasing section 16 a are formed in certain machining processes.
- Surface treatment layer 17 is formed extending from diameter-increasing section 16 a to the inside of lubricating oil supply hole 16 .
- pierced lubricating oil supply hole 16 of valve lifter may be used as an air hole.
- the principle of the present invention may be applied to a valve lifter on the side of an exhaust valve.
- the diamond-like carbon treatment has been described as being carried out at least after diameter-increasing section 16 a is formed, the forming and machining process is not limited to that described above.
Abstract
A forming and processing method for a valve lifter. The forming and processing method includes the steps of: (a) forming a hole in the valve lifter at a site where a cam is slidably contacted with; (b) forming a diameter-increasing section along an edge of the valve lifter, the edge defining a part of the hole and being located on a side with which the cam is slidably contacted; and (c) carrying out a surface treatment to whole of a surface of the valve lifter which surface is on the side with which the cam is slidably contacted.
Description
- This invention relates to improvements in a valve lifter in an internal combustion engine, and in a forming and processing method of the valve lifter, and more particularly to improvements in a surface treatment method for a top surface of a crown section or a shim of the valve lifter with which a cam formed to a camshaft is in slidable contact.
- In a directly driven type valve lifter of an internal combustion engine, a high frictional resistance is produced between a boss section of a bottom surface of a crown section and a stem end of an intake valve during engine operation. In view of this, a technique as disclosed in Japanese Patent Provisional Publication No. 2001-342810 is proposed, in which a lubricating oil supply hole is formed piercing the crown section of the valve lifter in order to positively supply lubricating oil between the boss section and the stem end.
- Additionally, regarding a shim installed to fit in a recess formed at a top surface of the crown section of the valve lifter, some techniques are proposed in which an air hole for blowing air into between a bottom surface of the recess and a bottom surface of the shim is formed piercing the shim. Air is blown through the air hole when the shim is detached from the recess in order to exchange the shim.
- Although the lubricating oil supply hole or the air hole is formed on an outer peripheral side of the top surface of the crown section or the shim, a cam formed to a camshaft is in slidable contact with an edge defining the lubricating oil supply hole or the air hole because the cam is in slidable contact with the generally whole top surface in a diametrical direction of the crown section or the shim in order to ensure a high lift amount of the intake valve. Hence, there is a fear that a bearing pressure applied to the edge defining the lubricating oil supply hole or the air hole becomes high when the cam is in slidable contact with the edge.
- Therefore, a contrivance to lower the bearing pressure is performed in such a manner that the edge defining the upper end of lubricating oil supply hole or the air hole is chamfered to form a diameter-increasing or flared section.
- Moreover, in view of the fact that the cam heavily slides and rotates on the top surface of the crown section or the shim, a surface treatment is carried out on the top surface of the crown section or the shim so that a surface treatment layer high in hardness is formed in order to lower a sliding frictional resistance and to ensure a wear resistance.
- However, regarding the above-mentioned conventional technique in which the surface treatment layer high in hardness is formed on the top surface of the crown section or the shim, the surface treatment layer on the diameter-increasing section is unavoidably thin-walled since the diameter-increasing section is formed along the edge defining the opening of the upper end of the lubricating oil supply hole or the air hole after the surface treatment is carried out.
- Accordingly, as shown in
FIG. 9 , there is a fear thatsurface treatment layer 23 is partly peeled off from diameter-increasingsection 22 a of lubricatingoil supply hole 22 under a condition in which the cam is continuously slidable contact with the top surface of disk-shaped shim 21 installed to fit in the recess formed at the top surface of the crown section. - Consequently, wear is liable to occur originating at
peeled part 24 ofsurface treatment layer 23 so as to unavoidably lower durability of the valve lifter. - It is, therefore, an object of the present invention to provide improved valve lifter and forming and processing method therefor which can effectively overcome drawbacks encountered in conventional valve lifters and forming and processing methods therefor.
- An aspect of the present invention resides in a forming and processing method for a valve lifter which method comprises the steps of: (a) forming a hole in the valve lifter at a site where a cam is slidably contacted with; (b) forming a diameter-increasing section along an edge of the valve lifter, the edge defining a part of the hole and being located on a side with which the cam is slidably contacted; and (c) carrying out a surface treatment to whole of a surface of the valve lifter which surface is on the side with which the cam is slidably contacted.
- Another aspect of the present invention resides in a valve lifter which comprises a crown section formed with a hole at a site where a cam is slidably contacted and having an edge of the valve lifter. The edge defines a part of the hole. A diameter-increasing section is formed along the edge. A skirt section is formed integral with an outer peripheral edge of the crown section. A surface treatment layer is formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
- A further aspect of the present invention resides in a valve lifter which comprises a crown section formed with a circular recess and an oil hole formed to communicate with the recess so as to pierce the crown section. A skirt section is formed integral with an outer peripheral edge of the crown section. A shim is accommodated in the recess and formed with a hole piercing the shim. A diameter-increasing section is formed along an edge defining a part of the hole. A surface treatment layer is formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
- The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.
-
FIG. 1 is a fragmentary cross-sectional view of an essential part of a first embodiment of a valve lifter according to the present invention; -
FIG. 2 is a longitudinal sectional view of the valve lifter ofFIG. 1 ; -
FIG. 3 is a top plan view of the valve lifter ofFIG. 1 ; -
FIG. 4 is a fragmentary cross-sectional view of the essential part of a valve lifter used for an endurance test for the comparison purpose; -
FIG. 5 is a cross-sectional view of a valve operating system of an internal combustion engine to which the first embodiment of the valve lifter is applied; -
FIG. 6 is a fragmentary cross-sectional view of the essential part of a second embodiment of the valve lifter according to the present invention; -
FIG. 7A is a longitudinal sectional view of a valve lifter and a cam under a condition in which they are contacted with each other; -
FIG. 7B is a cross-sectional view taken on line A-A ofFIG. 7A ; -
FIG. 8 is a longitudinal sectional view of a fourth embodiment of the valve lifter according to the present invention; and -
FIG. 9 is a fragmentary enlarged view of a part around a diameter-increasing section of a valve lifter according to a conventional technique, showing a peeling phenomenon of a diamond-like carbon layer at the diameter-increasing section due to a conventional forming process. - Referring now to FIGS. 1 to 3 and 5, a first embodiment of a valve lifter according to the present invention is illustrated by
reference numerals lifter - The valve operating system is shown in
FIG. 5 and includes intake andexhaust valves intake port 1 a andexhaust port 1 b which are communicated with a combustion chamber (not identified) and formed in cylinder head 1. Camshafts 4, 4 provided on intake and exhaust sides are rotatably supported through bearings (not shown) to upper end sections of cylinder head 1.Driving cams camshafts Valve lifters driving cams exhaust valves Valve lifters small diameter bores - Intake and
exhaust valves intake port 1 a andexhaust port 1 b respectively byvalve springs spring retainer 11 provided to upper end section of each valve stem and the bottom surface of each small diameter bore 1 c, 1 d. Intake andexhaust valves cylindrical valve guides - Rotational driving force of the engine is transferred to
camshafts cams camshafts exhaust valves intake port 1 a andexhaust port 1 b. - Each of driving
cams Cam surfaces driving cams upper surfaces 14 a ofcrown sections 14 ofvalve lifters cam surfaces - Regarding
valve lifters side valve lifter 7 as a matter of convenience. As illustrated inFIGS. 2 and 3 ,valve lifter 7 is formed of an iron-based metallic material as a one-piece member and includes as the mainparts crown section 14 andcylindrical skirt section 15.Crown section 14 is a circular upper wall section.Cylindrical skirt section 15 is formed integral with an outer peripheral edge ofcrown section 14. -
Crown section 14 hascrown surface 14 a which is the top surface ofcrown section 14 and gently spherical or round. In other words,crown surface 14 a is a part of the surface of a large sphere.Crown section 14 includesboss section 14 b which is contacted with a stem end ofintake valve 2 and formed in the generally cylindrical shape.Boss section 14 b is located at the central portion of a bottom surface ofcrown section 14. In order to introduce lubricating oil adhering oncrown surface 14 a into the inside ofvalve lifter 7 throughcam surface 5 a ofdriving cam 5, lubricatingoil supply hole 16 is formed at a certain position in a circumferential direction of the valve lifter and on an outer peripheral side ofcrown section 14 in a manner to piercecrown section 14. In addition, diameter-increasing or flaredsection 16 a (chamfered section) is formed at an annular portion or edge (of crown section 14) defining the upper open end portion of lubricatingoil supply hole 16. - Additionally,
surface treatment layer 17 high in hardness is formed on the whole ofcrown surface 14 a by using a diamond-like carbon treatment. A lapping treatment is made onsurface treatment layer 17 after the diamond-like carbon treatment. - Hereinafter, a forming and processing method for the whole of
valve lifter 7 will be discussed. - First, an iron-based metal as a base material is formed into a basic shape of
valve lifter 7 by cold forging, the basic shape being the shape of a cylinder having a closed bottom. - Then, surface machining is made on the top and bottom surfaces of
crown section 14 and the inner and outer peripheral surfaces ofskirt section 15. Additionally, machining for forming a hole is carried out at a certain position on the outer peripheral side ofcrown surface 14 a ofcrown section 14 so as to form lubricatingoil supply hole 16. It will be understood that lubricatingoil supply hole 16 may be formed during the above-mentioned cold forging. - Subsequently,
valve lifter 7 is subjected to a heat treatment such as carburizing, carbonitriding, nitriding or the like. Thereafter, polishing is made on the outer peripheral surfaces ofboss section 14 b andskirt section 15 so as to adjust the outer diameters ofboss section 14 b andskirt section 15 to the outer diameter of the stem end and the inner diameter ofbore - Subsequently, the whole of
crown surface 14 a is subjected to super-finishing so as to have a surface roughness (according to Japanese Industrial Standard JIS B0601) of about 0.1 μm. Additionally, the outer peripheral side ofcrown surface 14 a is subjected to so-called R-machining (rounding machining) by lapping, barreling, shotblasting and the like so as to have the surface roughness of about 0.2 μm. It will be understood that this surface treatment may be carried out during the above-mentioned polishing. At this time, diameter-increasing or flaredsection 16 a is formed on the annular portion or edge defining the upper open end portion of lubricatingoil supply hole 16, in such a manner that its round surface (in section or a vertical plane containing the axis of lubricating oil supply hole 16) has a radius of curvature R within a range of from about 0.05 to 0.2 mm. Additionally, the surface of diameter-increasingsection 16 a is subjected to finishing machining so as to have the surface roughness of about 0.2 μm. This diameter-increasingsection 16 a may be formed during the above polishing. - Thereafter,
valve lifter 7 is rinsed and then put into an oven for diamond-like carbon treatment. Then, the diamond-like carbon treatment is carried out on the whole ofcrown surface 14 a so as to form surface treatment layer or diamond-like carbon layer 17 high in hardness on the whole ofcrown surface 14 a. This diamond-like carbon treatment is carried out not only on the whole ofcrown surface 14 a but also on the inside surface of lubricatingoil supply hole 16 through the surface of diameter-increasingsection 16 a of lubricatingoil supply hole 16. - Subsequently, brush-lapping is carried out on the surface of
surface treatment layer 17, using diamond abrasive grains and a brush, in order to remove a certain amount of microparticles or molecules from the surface ofsurface treatment layer 17. With this, a plurality of minute recesses are formed atsurface treatment layer 17 such that the total area of the minute recesses is about 5 to 30% of the whole area ofcrown surface 14 a. It will be understood that this surface machining may be replaced with barreling, shotblasting or the like. - For evaluating the durability of the annular portion or edge defining the upper open end portion of lubricating
oil supply hole 16 on whichsurface treatment layer 17 is formed, endurance tests were conducted in such a defining the upper open end portion of lubricatingoil supply hole 16 for 100 hours under a condition in which the engine was operated at high speeds. The endurance tests were conducted on a valve lifter (7) of a type wherein lubricatingoil supply hole 16 had diameter-increasingsection 16 a whose surface was rounded as shown inFIG. 1 and on a valve lifter (7) of a type wherein lubricatingoil supply hole 16 had no diameter-increasingsection 16 a as shown inFIG. 4 . Regarding the valve lifter of the type wherein lubricatingoil supply hole 16 has diameter-increasingsection 16 a, the radius of curvature R (in section) of the round surface of diameter-increasingsection 16 a was varied. - As a result of the tests, with respect to the valve lifter of the type wherein lubricating
oil supply hole 16 had no diameter-increasingsection 16 a, wear was made at the surface ofcrown surface 14 a ofcrown section 14 due to, for example, increasing in bearing pressure. - On the other hand, with respect to the valve lifter of the type wherein lubricating
oil supply hole 16 had diameter-increasingsection 16 a, little wear was made. Particularly with respect to one having the round surface whose radius of curvature R was within a range of from 0.05 to 0.2 mm, no wear was made. In view of this, it is preferable that the round surface of diameter-increasingsection 16 a has a radius of curvature R within a range of from 0.05 to 0.2 mm. With this, the surface treatment layer or film becomes difficult to be peeled off while the bearing pressure can be lowered. - In the first embodiment, since
surface treatment layer 17 is formed on the whole ofcrown surface 14 a by carrying out the diamond-like carbon treatment after diameter-increasingsection 16 a having the round surface is formed at the annular portion or edge defining the upper open end portion of lubricatingoil supply hole 16,surface treatment layer 17 formed on diameter-increasingsection 16 a is prevented from decreasing in thickness. As a result,surface treatment layer 17 on diameter-increasingsection 16 a is prevented from peeling-off even if sliding movement ofcam surface 5 a is continued, so that a wear resistance of diameter-increasingsection 16 a is improved. - Further, since the diamond-like carbon treatment is carried out in an area extending from the whole of
crown surface 14 to the inside of lubricatingoil supply hole 16, peeling-off ofsurface treatment layer 17 is sufficiently inhibited even if a shearing force fromcam 5 is applied tosurface treatment layer 17. Further, in the first embodiment, since diameter-increasingsection 16 a is so formed as to have the round surface, i.e., so formed as to have no angular sections, generation of high bearing pressure is suppressed when cam surface 5 a is being slid onvalve lifter 7. - Further, in the first embodiment, the minute recesses are so formed that its total area becomes about 5 to 30% of the whole area of
crown surface 14 a by lapping aftersurface treatment layer 17 high in hardness is formed oncrown surface 14 a by the diamond-like carbon treatment. With the minute recesses, a frictional resistance betweencrown surface 14 a and cam surface 5 a can be reduced. Accordingly, a sufficient amount of lubricating oil is always retained in a plurality of minute recesses so that an oil film can be formed betweencrown surface 14 a and cam surface 5 a when cam surface 5 a is slid onvalve lifter 7. Consequently, the wear resistance ofvalve lifter 7 is improved, while the frictional resistance betweencrown surface 14 a ofvalve lifter 7 and cam surface 5 a ofcam 5 can be further lowered. -
FIG. 6 illustrates a second embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that diameter-increasingsection 16 a at the annular portion or edge defining the upper open end portion of lubricatingoil supply hole 16 is formed tapered or having a frustoconical surface in place of the round surface. - Namely, tapered diameter-increasing
section 16 a of the second embodiment is shaped into a reversed frustum of a cone having a generally flat surface which is straight in section. The diamond-like carbon treatment is carried out oncrown surface 14 a and the surface of the above tapered diameter-increasingsection 16 a after tapered diameter-increasingsection 16 a is formed. - Therefore, according to the second embodiment, effects as same as those in first embodiment are obtained. Besides, since diameter-increasing
section 16 a is formed tapered or frustoconical, its forming and machining is facilitated as compared with those in the first embodiment in which diameter-increasingsection 16 a is formed round in section. -
FIGS. 7A and 7B illustrate a third embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that crownsurface 14 a ofcrown section 14 ofvalve lifter 7 is spherically shaped having a large radius of curvature in section. On thisspherical crown surface 14 a,surface treatment layer 17 high in hardness is formed by the diamond-like carbon treatment. - Therefore, according to the third embodiment, since
cam surface 5 a is contacted withsurface treatment layer 17 in the condition of forming a contact point P, a sliding resistance between them is lowered. Besides, since the normal at the point P can approach an axis X by adjusting an inclination ofcam 5 or inclination of the axis ofcamshaft 4 as shown inFIG. 7B , a sliding resistance betweenvalve lifter 7 and the inner wall of small diameter bores 1 c can be lowered. -
FIG. 8 illustrates a fourth embodiment of the valve lifter according to the present invention, which is similar to the first embodiment with the exception that the main body ofvalve lifter 7 is formed of an aluminum alloy for weight-reduction, in whichcircular recess 19 is formed at the upper surface ofcrown section 14, disk-shapedshim 20 being accommodated incircular recess 19. -
Oil groove 19 a is annularly formed at a certain position of the outer peripheral side ofcircular recess 19. Besides,oil hole 19 b through which lubricating oil flows is formed at a certain position in a circumferential direction ofoil groove 19 a so as to communicate withoil groove 19 a and pierce the upper wall ofcrown section 14.Shim 20 is formed of an iron-based metal. Lubricatingoil supply hole 16 is formed at a certain position ofshim 20 which position corresponds tooil hole 19 b communicating withoil groove 19 a so as to pierceshim 20. Besides, diameter-increasingsection 16 a having the round surface is formed at the annular portion or edge defining the upper open end portion of lubricatingoil supply hole 16. Moreover, at the top surface ofshim 20 on whichcam 5 is to be slid,surface treatment layer 17 is formed by the diamond-like carbon treatment. Thissurface treatment layer 17 is formed by the diamond-like carbon treatment after lubricatingoil supply hole 16 and diameter-increasingsection 16 a are formed in certain machining processes.Surface treatment layer 17 is formed extending from diameter-increasingsection 16 a to the inside of lubricatingoil supply hole 16. - Therefore, according to the fourth embodiment, since
surface treatment layer 17 is formed after lubricatingoil supply hole 16 and diameter-increasingsection 16 a are formed, effects as same as those in the first embodiment can be obtained. - The entire contents of Japanese Patent Applications P2004-226230 (filed Aug. 3, 2004) are incorporated herein by reference.
- Although the invention has been described above by reference to certain embodiments and examples of the invention, the invention is not limited to the embodiments and examples described above. Modifications and variations of the embodiments and examples described above will occur to those skilled in the art, in light of the above teachings. For example, pierced lubricating
oil supply hole 16 of valve lifter may be used as an air hole. The principle of the present invention may be applied to a valve lifter on the side of an exhaust valve. Further, although the diamond-like carbon treatment has been described as being carried out at least after diameter-increasingsection 16 a is formed, the forming and machining process is not limited to that described above. - The scope of the invention is defined with reference to the following claims.
Claims (20)
1. A forming and processing method for a valve lifter, comprising the steps of:
forming a hole in the valve lifter at a site where a cam is slidably contacted with;
forming a diameter-increasing section along an edge of the valve lifter, the edge defining a part of the hole and being located on a side with which the cam is slidably contacted; and
carrying out a surface treatment to whole of a surface of the valve lifter which surface is on the side with which the cam is slidably contacted.
2. A forming and processing method as claimed in claim 1 , wherein the surface treatment is carried out in an area extending from the whole of the surface with which the cam is slidably contacted to inside of the hole through the diameter-increasing section formed along the annular edge of the valve lifter.
3. A forming and processing method as claimed in claims 1, wherein the diameter-increasing section is formed to have a round surface in section.
4. A forming and processing method as claimed in claim 3 , wherein the round surface of the diameter-increasing section has a radius of curvature within a range of from 0.05 to 0.2 mm in section.
5. A forming and processing method as claimed in claim 1 , wherein the diameter-increasing section is formed tapered.
6. A forming and processing method as claimed in claim 1 , wherein the surface treatment is a diamond-like carbon treatment.
7. A forming and processing method as claimed in claim 6 , wherein a lapping treatment is carried out after the diamond-like carbon treatment.
8. A forming and processing method as claimed in claim 1 , wherein a crown surface of the valve lifter is spherically formed.
9. A forming and processing method as claimed in claim 1 , wherein forming the hole is carried out after carrying out a surface processing of a crown section and inner and outer peripheral surface of a skirt section of the valve lifter.
10. A forming and processing method as claimed in claim 1 , wherein the hole is a lubricating oil supply hole and formed during cold forging of the valve lifter.
11. A forming and processing method as claimed in claim 1 , wherein the diameter-increasing section is formed after a heat treatment and a surface polishing which are carried out after the hole is formed.
12. A forming and processing method as claimed in claim 1 , the surface treatment is carried out after rinsing the valve lifter carried out after the diameter-increasing section is formed.
13. A valve lifter, comprising:
a crown section formed with a hole at a site where a cam is slidably contacted and having an edge of the valve lifter, the edge defining a part of the hole, a diameter-increasing section being formed along the edge;
a skirt section formed integral with an outer peripheral edge of the crown section; and
a surface treatment layer formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
14. A valve lifter as claimed in claim 13 , wherein the crown section and the skirt section are formed of an iron-based metal.
15. A valve lifter as claimed in claim 14 , wherein a minute recess is formed on the surface treatment layer.
16. A valve lifter, comprising:
a crown section formed with a circular recess and an oil hole formed to communicate with the recess so as to pierce the crown section;
a skirt section formed integral with an outer peripheral edge of the crown section;
a shim accommodated in the recess and formed with a hole piercing the shim, a diameter-increasing section being formed along an edge defining a part of the hole; and
a surface treatment layer formed on whole of a surface with which the cam is slidably contacted and on an area extending from the diameter-increasing section to inside of the hole.
17. A valve lifter as claimed in claim 16 , wherein a minute recess is formed at the surface treatment layer.
18. A valve lifter as claimed in claim 16 , wherein the crown section and the skirt section are formed of an aluminum alloy, and the shim is formed of an iron-based metal.
19. A valve lifter as claimed in claim 16 , an annular oil groove is formed to communicate with inside of the recess, wherein the oil hole is formed to communicate with a first position of the oil groove so as to pierce the crown section, wherein the hole in the shim is formed at a second position corresponding to the oil groove.
20. A valve lifter as claimed in claim 16 , wherein the hole is an air hole through which air flows.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2004-226230 | 2004-08-03 | ||
JP2004226230A JP2006046123A (en) | 2004-08-03 | 2004-08-03 | Surface treatment method of valve lifter |
Publications (1)
Publication Number | Publication Date |
---|---|
US20060027200A1 true US20060027200A1 (en) | 2006-02-09 |
Family
ID=35721709
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/185,810 Abandoned US20060027200A1 (en) | 2004-08-03 | 2005-07-21 | Valve lifter and forming and processing method therefor |
Country Status (5)
Country | Link |
---|---|
US (1) | US20060027200A1 (en) |
JP (1) | JP2006046123A (en) |
KR (1) | KR20060049014A (en) |
CN (1) | CN1734064A (en) |
DE (1) | DE102005036253B4 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US20080115752A1 (en) * | 2006-11-22 | 2008-05-22 | Hitachi, Ltd. | Engine valve lifter mechanism of internal combustion engine |
US20090283063A1 (en) * | 2008-05-19 | 2009-11-19 | Gm Global Technology Operations, Inc. | Wear Resistant Camshaft and Follower Material |
US20120073534A1 (en) * | 2010-09-28 | 2012-03-29 | Hitachi Automotive Systems, Ltd. | Valve lifter for internal combustion engine |
US20120255508A1 (en) * | 2011-04-08 | 2012-10-11 | Hitachi Automotive Systems, Ltd. | Valve Lifter of Internal Combustion Engine and Method of Fabricating the Valve Lifter |
WO2014057005A1 (en) * | 2012-10-10 | 2014-04-17 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for the surface treatment of coatings of hard carbon that are formed on substrates |
US20140245609A1 (en) * | 2009-04-23 | 2014-09-04 | Sumitomo Heavy Industries, Ltd. | Method of manufacturing regenerative refrigerator |
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Publication number | Priority date | Publication date | Assignee | Title |
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JP4293370B2 (en) * | 2005-02-02 | 2009-07-08 | 株式会社リケン | Valve lifter |
WO2011078533A2 (en) * | 2009-12-21 | 2011-06-30 | 두산인프라코어 주식회사 | Cam follower of which the structure is improved such that the limit load can be increased |
JP6001365B2 (en) * | 2012-07-20 | 2016-10-05 | 日立オートモティブシステムズ株式会社 | Valve lifter for internal combustion engine and method for manufacturing the valve lifter |
CN103302447B (en) * | 2013-03-19 | 2016-02-24 | 北京航星机器制造有限公司 | A kind of method of vacuum heat deep hole processing and deep hole hole-distance detecting device |
JP2013144988A (en) * | 2013-03-21 | 2013-07-25 | Hitachi Automotive Systems Ltd | Valve lifter for internal combustion engine |
CN107084013A (en) * | 2017-06-21 | 2017-08-22 | 浙江春风动力股份有限公司 | Engine and its cam assembly |
JP6793218B2 (en) * | 2019-04-18 | 2020-12-02 | 株式会社リケン | Sliding member |
CN110899783B (en) * | 2019-12-04 | 2021-02-26 | 湖北三江航天红阳机电有限公司 | Method for processing arc thin-wall aluminum alloy opening frame |
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DE1221846B (en) * | 1963-07-13 | 1966-07-28 | Volkswagenwerk Ag | Valve lash adjuster for internal combustion engines |
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- 2004-08-03 JP JP2004226230A patent/JP2006046123A/en active Pending
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2005
- 2005-07-21 US US11/185,810 patent/US20060027200A1/en not_active Abandoned
- 2005-08-02 DE DE102005036253A patent/DE102005036253B4/en not_active Expired - Fee Related
- 2005-08-02 KR KR1020050070453A patent/KR20060049014A/en not_active Application Discontinuation
- 2005-08-03 CN CNA2005100910188A patent/CN1734064A/en active Pending
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US5743224A (en) * | 1993-09-14 | 1998-04-28 | Unisia Jecs Corporation | Valve lifter surface and processing method thereof |
US5749341A (en) * | 1996-04-23 | 1998-05-12 | Unisia Jecs Corporation | Valve lifter for internal combustion engines |
US6237441B1 (en) * | 1998-03-19 | 2001-05-29 | Sumitomo Electric Industries, Ltd. | Combination of shim and cam |
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Publication number | Priority date | Publication date | Assignee | Title |
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US20080115752A1 (en) * | 2006-11-22 | 2008-05-22 | Hitachi, Ltd. | Engine valve lifter mechanism of internal combustion engine |
US7827946B2 (en) | 2006-11-22 | 2010-11-09 | Hitachi, Ltd. | Engine valve lifter mechanism of internal combustion engine |
US20090283063A1 (en) * | 2008-05-19 | 2009-11-19 | Gm Global Technology Operations, Inc. | Wear Resistant Camshaft and Follower Material |
US8109247B2 (en) * | 2008-05-19 | 2012-02-07 | GM Global Technology Operations LLC | Wear resistant camshaft and follower material |
US20140245609A1 (en) * | 2009-04-23 | 2014-09-04 | Sumitomo Heavy Industries, Ltd. | Method of manufacturing regenerative refrigerator |
US20120073534A1 (en) * | 2010-09-28 | 2012-03-29 | Hitachi Automotive Systems, Ltd. | Valve lifter for internal combustion engine |
US20120255508A1 (en) * | 2011-04-08 | 2012-10-11 | Hitachi Automotive Systems, Ltd. | Valve Lifter of Internal Combustion Engine and Method of Fabricating the Valve Lifter |
WO2014057005A1 (en) * | 2012-10-10 | 2014-04-17 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Method for the surface treatment of coatings of hard carbon that are formed on substrates |
Also Published As
Publication number | Publication date |
---|---|
KR20060049014A (en) | 2006-05-18 |
DE102005036253A1 (en) | 2006-02-23 |
JP2006046123A (en) | 2006-02-16 |
CN1734064A (en) | 2006-02-15 |
DE102005036253B4 (en) | 2008-02-28 |
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