JP2006328971A - Lash adjuster in valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a lowering in the function due to the intrusion of FM oil used for an engine, in a lash adjuster for automatically adjusting valve clearance of a swing arm type valve gear and a rocker arm type valve gear. <P>SOLUTION: A saw-toothed female screw 13 is formed on the inner periphery of a blocking-up end part of a cylindrical housing 11, and a male screw 15 formed on one end part outer periphery of an adjusting rod 14 is engaged by a screw with its female screw 13. The adjusting rod 14 is energized in the direction for separating from the blocking-up end by incorporating an elastic member 17 into the blocking-up end part of the housing 11. A seal ring 32 is installed in a seal groove 31 formed on the other end part outer periphery of the adjusting rod 14, and mutual sliding surfaces of the housing 11 and the adjusting rod 14 are sealed, to prevent the FM oil used for the engine from intruding between screw engaging parts of the female screw 13 and the male screw 15 from between the sliding surfaces. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lash adjuster that automatically adjusts the valve clearance of a valve gear in an internal combustion engine.

  In a valve operating device that opens and closes an intake valve or an exhaust valve (hereinafter simply referred to as a valve) by rotation of a cam, valve clearance is automatically adjusted by incorporating a lash adjuster.

  Here, as the valve operating device, there are a swing arm type valve operating device, a rocker arm type valve operating device, and a direct type valve operating device. Among these valve gears, a lash adjuster shown in FIG. 6 is conventionally known as a lash adjuster incorporated in a swing arm type valve gear.

  In the lash adjuster, a female screw 51 is formed on the inner periphery of the closed end portion of the cylindrical housing 50, and a male screw 53 formed on the outer periphery of the rear end portion of the adjusting rod 52 is thread-engaged with the female screw 51. The rod 52 is urged in a direction away from the closed end of the housing 50 by an elastic member 54 incorporated in the closed end portion of the housing 50, and the female screw 51 and the male screw 53 are respectively pushed into the adjusting rod 52. The flank angle of the pressure side flank 55 that receives the load is serrated larger than the flank angle of the play side flank 56.

  The lash adjuster is assembled in a support hole 9 formed in the cylinder head B, and is assembled so that one end of the swing arm 2 is swingably supported by a spherical portion 57 formed at the tip of the adjustment rod 52. Is done. When the swing arm 2 is pushed down by the rotation of the cam 1 provided on the swing arm 2 in the assembled state, the swing arm 2 swings around the spherical portion 57 and the valve stem 4 is valved at the other end. The spring 6 is pushed down against the elasticity.

  In general, when an axial compressive load is applied to a screw, the self-supporting friction coefficient μs (μs = tan α cos θ, where the friction coefficient μ between screw surfaces is determined by the screw specifications regardless of the magnitude of the axial load. , Α: lead angle, θ: flank angle), the screw is self-supporting without causing sliding rotation. On the contrary, if the friction coefficient μ between the screw faces is smaller than the self-supporting friction coefficient, the screw causes sliding rotation and is pushed in.

  In the conventional lash adjuster, the self-supporting friction coefficient μs of the pressure side flank 55 that receives the pushing load applied to the adjusting rod among the two flank of the serrated screw is smaller than the friction coefficient μ between the screw faces, and the play side flank The self-supporting friction coefficient μs of 56 is designed to be larger than the friction coefficient μ between the thread surfaces.

  As a result, when the lash adjuster is incorporated into the internal combustion engine, a valve clearance is generated between the upper end of the valve stem 4 and the other end of the swing arm 2 when the valve 7 is closed due to thermal expansion of the cylinder head B or the like. As a result, the adjusting rod 52 moves in the axial direction while rotating along the play-side flank 56 by the pressing force of the elastic member 54, and the other end of the swing arm 2 is moved downward by pushing up one end of the swing arm 2. The valve clearance is absorbed by swinging to move.

  Further, when the adjusting rod 52 receives a pressing force by the swing arm 2, the adjusting rod 52 moves backward until the axial screw gap formed in the screw engaging portion of the female screw 51 and the male screw 53 is filled, and further the pressing force is applied. Then, the adjustment rod 52 is prevented from moving backward while receiving the pushing force by the pressure side flank 55 pressed against each other.

  On the other hand, when a pushing force is applied from the valve stem 4 to the swing arm 2 due to wear of the valve seat 8 or the like, the adjusting rod 52 gradually moves due to the fluctuating axial load applied from the cam 1 via the swing arm 2. When the base circle 1a of the cam 1 comes into contact with the swing arm 2 by being pushed in, compression leakage due to the valve 7 not being completely closed is prevented. At this time, the adjusting rod 52 is further pushed in from the position where the minimum value of the fluctuating load in the axial direction becomes 0, and does not retreat further.

  In recent years, an engine oil containing organic molybdenum (friction modifier oil, hereinafter referred to as FM oil) has been generally used in automobile engines for the purpose of reducing friction and reducing direct contact between sliding parts. When FM oil is used, a reaction film having a very low friction coefficient is generated at the sliding portion, and the sliding resistance of each portion is reduced.

Typical examples of organic molybdenum mixed in FM oil include MoDTC (molybdenum dithiocarbamate) and MoDTP (molybdenum dithiophosphate), which generate a reaction film containing MoS ₂ (molybdenum disulfide) on the friction surface. It is known to reduce the coefficient of friction.

By the way, it has been experimentally confirmed that the friction coefficient in the sliding portion under lubrication with oil not containing organic molybdenum (hereinafter referred to as non-FM oil) is about 0.1 to 0.15. For example, the lead angle α = 11.5 °, the flank angle θ ₁ = 75 ° of the pressure side flank, and the flank angle θ ₂ = 15 ° of the play side flank of the adjusting rod incorporated in the lash adjuster of FIG. As a result, the self-supporting friction coefficient μs of the pressure side flank is smaller than 0.1 and the self-supporting friction coefficient μs of the play-side flank is larger than 0.15, thereby realizing the function of the lash adjuster under non-FM oil lubrication. it can.

  However, in the engine in which the lash adjuster is incorporated, when the FM oil is used, the friction coefficient μ between the screw surfaces may be extremely reduced to about 0.04, and the friction coefficient μ If it is less than the flank self-supporting friction coefficient μs, the pressure-side flank 55 may slip. If the slip on the pressure side flank 55 is excessive, the adjustment rod 52 is pushed when an axial load is applied to the lash adjuster, causing a valve lift loss and the valve 7 seating in an impact, causing abnormal noise. May occur.

  An object of the present invention is to provide a lash adjuster that can always exhibit a stable function even when engine oil such as FM oil that affects the friction coefficient of a screw surface is used in the engine. .

  In order to solve the above problems, a cylindrical housing having a closed end and having an internal thread formed on the inner periphery of the closed end, and a male screw engaged with the female screw of the housing on the outer periphery of the end The adjustment rod is formed with the other end facing the outside from the open end of the housing and an elastic member that urges the adjustment rod in a direction away from the closed end of the housing. The female screw and the male screw are loaded on the adjustment rod. In a lash adjuster in a valve operating device in which the flank angle of the pressure side flank receiving the axial pushing load is larger than the flank angle of the play side flank, the space between the sliding surface of the housing and the adjusting rod is sealed. The structure which provided the sealing means and enclosed the lubricant inside is employ | adopted.

  Here, the sealing means may incorporate a seal ring such as an O-ring between the sliding surfaces of the housing and the adjusting rod, or one end of the elastically deformable boot is fixed to the outer periphery of the opening end of the housing. Then, the other end may be fixed to the other end facing the outside of the housing of the adjusting rod.

  In the second invention, a cylindrical housing having a closed end and having an internal thread formed on the inner periphery of the closed end, and a male screw engaged with the female screw of the housing are formed on the outer periphery. An adjustment screw, a slide rod that is slidably inserted into the housing and has one end abutting the adjustment screw and the other end facing the outside of the housing, and the adjustment screw in a direction away from the closed end of the housing. The male screw formed on the outer periphery of the female screw and the adjusting screw is a serrated screw whose flank angle of the pressure side flank receiving the pushing load from the slide rod is larger than the flank angle of the play side flank. The lash adjuster is provided with a sealing means for sealing between the sliding surface of the housing and the slide rod. Adopts a configuration encapsulating lubricant therein.

  Here, the sealing means may incorporate a seal ring such as an O-ring between the sliding surfaces of the housing and the slide rod, or one end of the elastically deformable boot is fixed to the outer periphery of the opening end of the housing. Then, the other end may be fixed to the other end facing the outside of the housing of the slide rod.

  As in the first aspect of the invention, the engine oil that affects the friction coefficient of the screw surface such as FM oil is used for the engine by sealing between the sliding surface of the housing and the adjusting rod by the sealing means. Even in this case, it is possible to prevent the engine oil from entering between the threaded portions of the housing internal thread and the external thread of the adjusting rod, thereby suppressing the deterioration of the function of the lash adjuster and stabilizing the function. Can be planned.

  In addition, even when soot is mixed in engine oil and there is a concern about wear of a valve or the like including a lash adjuster, soot can be prevented from entering the housing and durability of the lash adjuster can be maintained. .

  When engine oil that affects the wear coefficient of the thread surface such as FM oil is used for the engine by sealing between the sliding surface of the housing and the slide rod by the sealing means as in the second invention However, as in the first invention, the engine oil can be prevented from entering between the screw engaging portions of the housing internal thread and the external screw of the adjusting screw, and the function of the lash adjuster can be suppressed. Can be stabilized.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a swing arm type valve gear, and a roller 3 that contacts the cam 1 is rotatably supported on a swing arm 2 provided below the cam 1. One end of the swing arm 2 is swingably supported by a lash adjuster A supported by the cylinder head B, and the other end of the swing arm 2 faces the upper end of the valve stem 4.

  The valve stem 4 has a spring retainer 5 at the upper end, and the valve stem 4 is urged in the direction in which the lower end valve 7 is in close contact with the valve seat 8 by the elastic force of the valve spring 6 applied to the spring retainer 5. At the same time, the swing arm 2 is urged by the valve stem 4 in the direction in which the roller 3 contacts the cam 1.

  As shown in FIG. 2, the lash adjuster A has a cylindrical housing 11. One end of the housing 11 is closed by attaching a cap 12, and a female screw 13 is formed on the inner periphery of the closed end.

  An adjusting rod 14 is incorporated in the housing 11. The adjusting rod 14 has a male screw 15 that is engaged with the female screw 13 of the housing 11 on the outer periphery of one end portion, and a spherical protrusion 16 that swingably supports one end portion of the swing arm 2 is provided on the other end portion. It has been. The adjusting rod 14 is urged in a direction away from the closed end of the housing 11 by an elastic member 17 incorporated in the closed end of the housing 11, and the adjusting rod 14 passes through the other end opening of the housing 11. A stopper ring 18 for stopping is attached.

  The internal thread 13 formed on the housing 11 and the external thread 15 formed on the adjusting rod 14 have a sawtooth shape in which the flank angle of the pressure side flank 19 that receives the pushing force applied to the adjusting rod 14 is larger than the flank angle of the play side flank 20. The saw-toothed screw is provided with a lead angle that moves in the axial direction while the adjusting rod 14 is rotated by the pressing of the elastic member 17.

  The sliding surface between the housing 11 and the adjusting rod 14 is sealed by a sealing means 30. Here, as the sealing means 30, a seal groove 31 is formed on the outer periphery of the portion of the adjusting rod 14 located in the housing 11, and a seal ring 32 formed of an O-ring fitted in the seal groove 31 is used as the inner diameter surface of the housing 11. In elastic contact.

  Alternatively, a seal groove may be formed on the inner diameter surface of the housing 11, and a seal ring may be fitted into the seal groove to be brought into elastic contact with the outer diameter surface of the adjustment rod.

  As shown in FIG. 1, the lash adjuster A configured as described above is inserted into a support hole 9 formed in the cylinder head B and swings by a spherical protrusion 16 formed at the other end of the adjustment rod 14. The arm 2 is assembled to support one end of the arm 2 in a swingable manner.

  In the assembly to the valve operating apparatus as described above, the lash adjuster A automatically adjusts the change in the valve clearance generated in the valve operating apparatus due to the thermal expansion of the cylinder head B, the wear of the valve seat 8, and the like. To do. Since the adjustment of the valve clearance is the same as that of the conventional lash adjuster, description thereof is omitted.

  Note that, in a steady operation state where adjustment of the valve clearance is not necessary, the adjusting rod 14 hardly rotates and is formed between the screw engaging portions of the female screw 13 of the housing 11 and the male screw 15 of the adjusting rod 14. Repeated axial displacement within the screw gap.

  In the lash adjuster A shown in FIG. 2, since the seal ring 32 is incorporated between the sliding surfaces of the housing 11 and the adjusting rod 14 and the sliding surfaces are sealed, the engine has screw surfaces such as FM oil. Even when engine oil that affects the coefficient of friction is used, the engine oil does not enter between the screw engaging portions of the female screw 13 of the housing 11 and the male screw 15 of the adjusting rod 14, Since the friction coefficient does not change, it is possible to maintain a stable function.

  FIG. 3 shows another example of the sealing means 30 for sealing between the sliding surfaces of the housing 11 and the adjusting rod 14. In this example, one end of an elastically deformable boot 33 is fixed to the outer periphery of a stopper ring 18 attached to the opening end of the housing 11, and the other end of the boot 33 is formed at the other end of the adjusting rod 14. The spherical protrusion 16 is fixed to the neck 16a. Note that the stopper ring 18 may be omitted, and the boot 33 may be directly fixed to the opening end of the housing 11.

  Also in the sealing means 30, engine oil can be prevented from entering between the screw engaging portions of the female screw 13 of the housing 11 and the male screw 15 of the adjusting rod 14.

  FIG. 4 shows another example of the lash adjuster A. In this example, the adjustment rod 14 of the lash adjuster A shown in FIG. 2 is separated into an adjustment screw 21 that is screw-engaged with the female screw 13 and a slide rod 22 that has a spherical protrusion 16, and is formed at one end of the slide rod 22. The spherical surface 23 is brought into point contact with the adjusting screw 21. Since other configurations are the same as those of the lash adjuster shown in FIG. 2, the same components are denoted by the same reference numerals and description thereof is omitted.

  Also in the lash adjuster A described above, the engine oil enters between the screw engaging portions of the female screw 13 of the housing 11 and the male screw 15 of the adjusting screw 21 by the seal ring 32 incorporated between the sliding surface of the slide rod 22 and the housing 11. Can be prevented.

  Instead of the seal ring 32, a space between the sliding surfaces of the housing 11 and the slide rod 22 may be sealed by attaching a boot 33 shown in FIG.

  1 shows a swing arm type valve operating apparatus, and the lash adjuster A shown in FIGS. 2 to 4 is incorporated in the valve operating apparatus. However, the rocker arm type valve operating apparatus shown in FIG. The lash adjuster A shown in FIG. 4 can be applied.

  Here, in the rocker arm type valve gear, the roller 42 at one end of the rocker arm 41 supported so as to be swingable about the shaft 40 is brought into contact with the cam 43, and the rotation of the cam 43 causes the shaft 40 to be centered. The rocker arm 41 is swung, and the valve stem 4 is pushed down at the other end of the rocker arm 41.

  When the lash adjuster A shown in FIGS. 2 to 4 is employed in the above rocker arm type valve gear, a mounting hole 44 is formed in the other end of the rocker arm 41 so as to penetrate vertically, and the housing 11 is placed in the mounting hole 44. Press fit. At this time, the housing 11 is press-fitted into the mounting hole 44 with the closed end of one end facing upward, and the housing 11 is prevented from rotating, and the spherical protrusion 16 at the other end of the adjusting rod 14 or the spherical protrusion at the other end of the slide rod 22. The part 16 is brought into contact with the upper end of the valve stem 4 or through a seat plate.

Longitudinal front view of a swing arm type valve gear incorporating a lash adjuster according to the present invention Enlarged sectional view of the lash adjuster shown in FIG. Sectional drawing which shows the other example of a sealing device Sectional drawing which shows other embodiment of the lash adjuster which concerns on this invention Sectional drawing of the rocker arm type valve gear incorporating the lash adjuster according to the present invention Longitudinal front view of a swing arm type valve gear incorporating a conventional lash adjuster

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Housing 13 Female screw 14 Adjustment rod 15 Male screw 17 Elastic member 19 Pressure side flank 20 Play side flank 21 Adjustment screw 22 Slide rod 30 Sealing means 31 Seal groove 32 Seal ring 33 Boot

Claims (6)

  A cylindrical housing having a closed end and having an internal thread formed on the inner periphery of the closed end, a male screw engaged with the female screw of the housing is formed on the outer periphery of one end, and the other end of the housing is An adjustment rod that faces the outside from the open end and an elastic member that urges the adjustment rod in a direction away from the closed end of the housing, and receives the axial pushing load applied to the adjustment rod by the female screw and the male screw. In a lash adjuster in a valve operating device in which the flank angle of the pressure side flank is larger than the flank angle of the idle side flank, a sealing means for sealing between the sliding surface of the housing and the adjusting rod is provided and lubricated inside. A lash adjuster in a valve operating device characterized in that an agent is enclosed.   The lash adjuster in the valve operating apparatus according to claim 1, wherein the sealing means comprises a seal ring incorporated between sliding surfaces of the housing and the adjusting rod.   2. The sealing means according to claim 1, comprising an elastically deformable boot having one end fixed to the outer periphery of the opening end of the housing and the other end fixed to the other end facing the outside of the housing of the adjusting rod. Rush adjuster in valve gear.   A cylindrical housing having a closed end and having a female screw formed on the inner periphery of the closed end, an adjustment screw having a male screw threadedly engaged with the female screw of the housing, and an inside of the housing A slide rod that is slidably inserted and has one end abutting on the adjustment screw and the other end facing the outside of the housing, and an elastic member that urges the adjustment screw in a direction away from the closed end of the housing, In the lash adjuster in the valve operating apparatus, the male screw formed on the outer periphery of the female screw and the adjusting screw is a saw-tooth screw in which the flank angle of the pressure side flank receiving the pushing load from the slide rod is larger than the flank angle of the play side flank. A sealing means for sealing between the sliding surface of the housing and the slide rod is provided. Lash adjuster in a valve operating device for.   The lash adjuster in the valve operating apparatus according to claim 4, wherein the sealing means comprises a seal ring incorporated between the sliding surfaces of the housing and the slide rod.   5. The sealing means according to claim 4, wherein the sealing means comprises an elastically deformable boot having one end fixed to the outer periphery of the opening end of the housing and the other end fixed to the other end facing the outside of the housing of the slide rod. Rush adjuster in valve gear.

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