JP2008267143A - Lash adjuster - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lash adjuster superior in durability, which causes little retention of abrasion powder between contact surfaces of a female screw and a male screw. <P>SOLUTION: This lash adjuster 1 has: a cylindrical housing 14 having the opening upper end; a screw rod 15 having on the outer periphery the male screw 17 engaging by a screw with the female screw 18 formed on the inner periphery of its housing 14; and a return spring 16 energizing its screw rod 15 in the direction for projecting from the housing 14, and is constituted so that the female screw 18 and the male screw 17 are formed so that a flank angle of a pressure side flank 19 for receiving pressure when force in the direction for pushing the screw rod 15 in the housing 14 acts on them, becomes larger than a flank angle of a play side flank 20, and that a rocking fulcrum of an arm 6 of a valve gear is held by the projecting end 27 from the housing 14 of the screw rod 15. A lubricating oil discharge hole 25 communicating with the inside and outside of the housing 14, is formed on the lower end of the housing 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lash adjuster incorporated in an engine valve gear.

  As a valve operating device for operating a valve provided at an intake port or an exhaust port of an engine, a valve operating device in which a valve stem connected to the valve is pushed and moved by an arm that swings according to the rotation of a cam is often used. .

  In such a valve operating apparatus, when the valve operating apparatus thermally expands due to a temperature rise during engine operation, a difference in thermal expansion that occurs between the structural members of the valve operating apparatus causes a difference (for example, between an arm and a valve) A gap occurs between the stems), and the gap may cause abnormal noise or a deviation in valve opening / closing timing. In addition, due to wear of the sliding portion of the valve operating device, a gap is generated between the constituent members of the valve operating device (for example, between the valve and the valve seat), and abnormal noise or the like may occur due to the clearance.

  Therefore, in order to absorb the gaps between the components of the valve gear, the arm swing fulcrum is often supported by a lash adjuster, and the position of the arm swing fulcrum is automatically adjusted by the lash adjuster.

  As such a lash adjuster, a cylindrical housing whose upper end is open and whose lower end is closed, a screw rod having a male screw on the outer periphery that engages with a female screw formed on the inner periphery of the housing, and the screw rod A return spring that biases in a direction projecting from the housing (hereinafter referred to as a “projection direction”) and that supports the swing fulcrum of the arm at the projecting end of the screw rod from the housing is known. (Patent Document 1).

  The male screw on the outer periphery of the screw rod of this lash adjuster and the female screw on the inner periphery of the housing are the flank of the pressure side flank that receives pressure when a force in the direction of pushing the screw rod into the housing (hereinafter referred to as “pushing direction”) is applied. The angle is formed larger than the flank angle of the play side flank.

Also, this lash adjuster allows the pressure-side flank of the male screw on the outer periphery of the screw rod to be received by the pressure-side flank of the female screw on the inner periphery of the housing when the force in the pushing direction acts on the screw rod due to the rotation of the cam. The axial position of is fixed. Also, when the relative position of the arm and valve stem changes due to thermal expansion of the valve operating device, etc., the screw rod moves in the axial direction while rotating in the housing according to the change in position, and the valve operating device Absorb gaps between components.
JP 2005-248912 A

  However, in this lash adjuster, since the lower end of the housing is closed, the lubricating oil tends to stay in the housing. For this reason, there is a problem that the wear powder due to the contact between the female screw and the male screw stays between the contact surfaces of the female screw and the male screw, and the wear powder promotes the wear of the female screw and the male screw, thereby reducing the life of the lash adjuster.

  The problem to be solved by the present invention is to provide a lash adjuster that is less likely to retain abrasion powder between the contact surfaces of a female screw and a male screw, and that is excellent in durability.

  In order to solve the above problems, a lubricating oil discharge hole that communicates the inside and outside of the housing is formed at the lower end of the housing.

In this lash adjuster, it is preferable to form a lubricating oil introduction hole from the outer periphery to the inner periphery of the housing, and to open the lubricating oil introduction hole into the female screw, and it is preferable to add the following configuration.
1) A circumferential groove communicating with the lubricating oil introduction hole is formed on the outer periphery of the housing.
2) The flow area of the lubricating oil supplied from the lubricating oil introduction hole into the housing, the flow area of the lubricating oil discharged from the gap between the female screw and the male screw at the upper end of the housing, and the lubricating oil discharge hole Make it smaller than the total flow passage area of the lubricating oil.

  In the lash adjuster of the present invention, the lubricating oil in the housing is discharged from the lubricating oil discharge hole at the lower end of the housing, and the wear powder due to the contact between the female screw and the male screw is discharged together with the lubricating oil. Wear powder hardly stays between the surfaces, and wear is not easily accelerated by the wear powder.

  In addition, a lubricating oil introduction hole that extends from the outer periphery to the inner periphery of the housing, and the lubricating oil introduction hole is opened in the female screw, is supplied by supplying the lubricating oil into the housing from the lubricating oil introduction hole. The abrasion powder between the contact surfaces of the female screw and the male screw can be discharged more effectively.

  Further, the outer periphery of the housing formed with a circumferential groove communicating with the lubricating oil introduction hole includes a position of the lubricating oil supply hole for supplying the lubricating oil to the lubricating oil introducing hole, and a position of the lubricating oil introducing hole. The lash adjuster can be easily installed.

  In addition, the flow area of the lubricating oil supplied into the housing from the lubricating oil introduction hole, the flow area of the lubricating oil discharged from the gap between the female screw and the male screw at the upper end of the housing, and the lubricating oil discharge hole Since the pressure of the lubricating oil in the gap between the female screw and the male screw does not easily increase when the lubricating oil passage area is smaller than the total flow passage area, the axial force acting on the screw rod can be quickly received by the housing.

  FIG. 1 shows a valve gear incorporating a lash adjuster 1 according to an embodiment of the present invention. This valve operating apparatus includes a valve 4 provided in an intake port 3 of an engine cylinder head 2, a valve stem 5 connected to the valve 4, and an arm 6 that is swingably supported by a lash adjuster 1. Have.

  The valve stem 5 extends upward from the valve 4 and slidably penetrates the cylinder head 2. An annular spring retainer 7 is fixed to the upper outer periphery of the valve stem 5, and a valve spring 8 is incorporated between the lower surface of the spring retainer 7 and the upper surface of the cylinder head 2. The valve spring 8 urges the valve stem 5 upward via the spring retainer 7, and the valve 4 is seated on the valve seat 9 by the urging force.

  One end of the arm 6 is supported by the lash adjuster 1, and the other end is in contact with the upper end of the valve stem 5. A roller 10 is attached to the central portion of the arm 6, and the roller 10 is in contact with a cam 11 provided above the arm 6. The cam 11 is fixed to the outer periphery of the camshaft 12, and when the camshaft 12 rotates, the cam crest portion 11 b raised with respect to the base circle 11 a pushes down the arm 6 via the roller 10.

  The lash adjuster 1 is accommodated in an accommodation hole 13 formed in the upper surface of the cylinder head 2. The lash adjuster 1 includes a cylindrical housing 14 whose upper end is open, a screw rod 15 inserted into the housing 14, and a return spring 16.

  As shown in FIG. 2, a male screw 17 is formed on the lower outer periphery of the screw rod 15, and the male screw 17 is engaged with a female screw 18 formed on the inner periphery of the housing 14. The female screw 18 and the male screw 17 are formed in a sawtooth shape having an asymmetric cross section along the axis, and the pressure side flank 19 that receives pressure when a force in the direction of pushing the screw rod 15 into the housing 14 is applied. The flank angle is larger than the flank angle of the play side flank 20.

  A circumferential groove 22 is formed on the outer periphery of the housing 14 so as to communicate with the lubricating oil supply hole 21 that opens to the inner periphery of the accommodation hole 13. The circumferential groove 22 is a lubricant that extends from the outer periphery of the housing 14 to the inner periphery. It communicates with the introduction hole 23. The lubricating oil introduction hole 23 opens to the female screw 18 on the inner periphery of the housing 14, and the lubricating oil supplied from the lubricating oil supply hole 21 passes through the circumferential groove 22 and the lubricating oil introduction hole 23 in this order, and the female screw. 18 is supplied to the gap between the male screw 17 and the male screw 17.

  A bottom 24 is provided at the lower end of the housing 14. The bottom 24 is formed with a lubricating oil discharge hole 25 communicating with the inside and outside of the housing 14. The lubricating oil supplied from the lubricating oil introduction hole 23 into the housing 14 is supplied to the lubricating oil discharge hole 25 and the accommodation hole 13. Are discharged through the through-holes 26 formed in the bottom surface in order. The lubricating oil supplied from the lubricating oil introduction hole 23 into the housing 14 is also discharged from the gap between the female screw 18 and the male screw 17 at the upper end of the housing 14.

  The lubricating oil introduction hole 23 is formed so that the flow area is smaller than the total of the flow area of the gap between the female screw 18 and the male screw 17 and the flow area of the lubricating oil discharge hole 25.

  The return spring 16 is incorporated between the screw rod 15 and the bottom 24 of the housing 14, and urges the screw rod 15 to protrude from the housing 14. The screw rod 15 has a hemispherical projecting end 27 from the housing 14, and the projecting end 27 fits into a recess 28 formed on the lower surface of the arm 6 as shown in FIG. The arm 6 is supported so as to be able to oscillate, with 28 as a fulcrum.

  In this valve operating apparatus, when the cam shaft 12 rotates and the cam crest 11b of the cam 11 pushes down the arm 6, the valve 4 is separated from the valve seat 9 and the intake port 3 is opened. At this time, a force in the pushing direction acts on the screw rod 15, but the pressure side flank 19 of the male screw 17 is received by the pressure side flank 19 of the female screw 18, so that the axial position of the screw rod 15 is fixed.

  Further, when the camshaft 12 rotates and the cam crest 11b passes the position of the roller 10, the valve stem 5 is raised by the urging force of the valve spring 8, the valve 4 is seated on the valve seat 9, and the intake port Close 3

  Further, when a difference in thermal expansion occurs between the components of the valve operating device such as the cylinder head 2, the valve stem 5, and the arm 6 during engine operation, and the distance between the cam 11 and the arm 6 increases, Since the rod 15 moves in the protruding direction while being rotated by the urging force of the return spring 16, no gap is formed between the base circle 11 a of the cam 11 and the roller 10, and the valve 4 is impactably seated on the valve seat 9. Things are prevented.

  Further, when the contact surface between the valve 4 and the valve seat 9 is worn, the screw rod 15 moves in the pushing direction while rotating by the urging force of the valve spring 8, and the valve stem 5 rises. There is no gap between the contact surfaces of the sheet 9.

  Further, during the operation of the engine, an oil pump (not shown) is operated to supply the lubricating oil from the lubricating oil supply hole 21, and the lubricating oil passes through the circumferential groove 22 and the lubricating oil introducing hole 23 in order. 14 is supplied to lubricate between the internal thread 18 and the external thread 17.

  In the lash adjuster 1, the lubricating oil in the housing 14 is discharged from the lubricating oil discharge hole 25, and wear powder due to the contact between the female screw 18 and the male screw 17 is discharged together with the lubricating oil. Therefore, the wear powder due to the contact between the female screw 18 and the male screw 17 is unlikely to stay between the contact surfaces of the female screw 18 and the male screw 17, and the wear is not easily accelerated by the wear powder.

  Further, since the circumferential adjuster 22 is formed on the outer periphery of the housing 14, the lash adjuster 1 has a position of the lubricating oil supply hole 21 and the position of the lubricating oil introduction hole 23 when the housing 14 is inserted into the receiving hole 13. There is no need to match the position, and the installation work of the lash adjuster 1 is simple.

  Further, in the lash adjuster 1, the flow area of the lubricating oil supplied from the lubricating oil introduction hole 23 into the housing 14 has a flow path of the lubricating oil discharged from the gap between the female screw 18 and the male screw 17 at the upper end of the housing 14. Since it is smaller than the sum of the area and the flow passage area of the lubricating oil discharged from the lubricating oil discharge hole 25, the pressure of the lubricating oil in the gap between the female screw 18 and the male screw 17 is difficult to increase. Therefore, when the cam 11 rotates, the axial force acting on the screw rod 15 can be quickly received by the housing 14, and the screw rod 15 moves in the pushing direction even at a low temperature when the viscosity of the lubricating oil is large. Can be prevented.

  In the above embodiment, by supplying the lubricating oil into the housing 14 from the lubricating oil introduction hole 23, the abrasion powder between the contact surfaces of the female screw 18 and the male screw 17 can be discharged more effectively. However, the lubricating oil introduction hole 23 is not essential, and the lubricating oil may be supplied into the housing 14 from the gap between the female screw 18 and the male screw 17 at the upper end of the housing 14.

The front view which shows the valve operating apparatus incorporating the lash adjuster of embodiment of this invention Enlarged sectional view of the lash adjuster shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 6 Arm 14 Housing 15 Screw rod 16 Return spring 17 Male thread 18 Female thread 19 Pressure side flank 20 Play side flank 22 Circumferential groove 23 Lubricating oil introduction hole 25 Lubricating oil discharge hole 27 Projection end

Claims (4)

  A cylindrical housing (14) whose upper end is open, a screw rod (15) having a male screw (17) on its outer periphery that engages with a female screw (18) formed on the inner periphery of the housing (14), and A return spring (16) for urging the screw rod (15) in a direction protruding from the housing (14), and the female screw (18) and the male screw (17) (14) The flank angle of the pressure flank (19) that receives pressure when a force in the direction of pushing in is applied is greater than the flank angle of the play flank (20), and the screw rod ( 15) on the lash adjuster (1) adapted to support the swing fulcrum of the arm (6) of the valve gear by the projecting end (27) from the housing (14). There are, at the lower end of the housing (14), a lash adjuster, characterized in that the formation of the housing (14) lubricant discharge hole communicating the inside and outside of (25).   The lash adjuster according to claim 1, wherein a lubricating oil introduction hole (23) extending from an outer periphery to an inner periphery of the housing (14) is formed, and the lubricating oil introduction hole (23) is opened in the female screw (18).   The lash adjuster according to claim 2, wherein a circumferential groove (22) communicating with the lubricating oil introduction hole (23) is formed on an outer periphery of the housing (14).   The flow path area of the lubricating oil supplied from the lubricating oil introduction hole (23) into the housing (14) is set so that the lubricating oil discharged from the gap between the female screw (18) and the male screw (17) at the upper end of the housing (14) The lash adjuster according to claim 2 or 3, wherein the lash adjuster is smaller than a total of the flow path area and the flow path area of the lubricating oil discharged from the lubricating oil discharge hole (25).

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