JP2005248912A - Valve clearance-automatically adjusting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize the amount of valve lift of a valve train in which a valve clearance-automatically adjusting device utilizing buttress threads is incorporated. <P>SOLUTION: An arm support member 11 of a lash adjuster 1 serving as the valve clearance-automatically adjusting device is separated in a pivot member 9 which supports one end portion of an arm 5 of the valve train, and a male thread member 10 screwingly engaged through the buttress threads with a female thread member 12 secured to a cylinder head 6 of the valve train. When the pivot member 9 moves at the one end portion of the arm 5 in a sliding manner, the rotating force transmitted from the arm 5 to the pivot member 9 owing to the backlash or the like between the arm and the pivot member is prevented from being conveyed to the male thread member 10, so that the rotation of the male thread member 10 which is irrelevant to its original function is inhibited, thereby stabilizing the position where the pivot member 9 supports the arm 5. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an automatic valve clearance adjusting device incorporated in a valve mechanism of an internal combustion engine.

  The valve mechanism of the internal combustion engine includes a direct type that directly opens and closes the valve by a camshaft provided on the axis of the reciprocating motion, and an arm that swings with a position off the axis of the reciprocating motion of the valve as a fulcrum. It can be roughly divided into the arm type performed via Among arm types, there is a so-called swing arm type that does not have a fixed shaft that penetrates the fulcrum, supports one end of the arm with a pivot, and reciprocates the valve at the other end of the arm.

  In the above swing arm type valve mechanism, the valve clearance (clearance between the valve shaft end and the other end of the arm) is usually kept constant against variations in assembly accuracy, wear of the valve seat, thermal expansion of the cylinder head, and the like. In order to maintain, an automatic valve clearance adjustment device called a lash adjuster is incorporated on the pivot side. As this lash adjuster, in addition to the hydraulic type, one using a sawtooth screw has been proposed (for example, see Patent Documents 1 and 2).

  FIG. 5 shows an example of a swing arm type valve operating mechanism incorporating a conventional sawtooth screw type lash adjuster 51. In this valve operating mechanism, when the cam shaft 3 rotates and pushes the central portion of the arm 5 with the cam 4 from the closed state of the valve 2 shown in FIG. 5, the arm 5 swings with its one end supported by the lash adjuster 51. Then, by pushing down the valve 2 at the other end, the valve 2 is separated from the valve seat 7 attached to the cylinder head 6 and is opened. When the cam 4 moves away from the arm 5, the valve 2 is pulled back by the force of the valve spring 8 and closed again.

  The lash adjuster 51 incorporated in the valve operating mechanism includes an arm support member 52 having a pivot portion 52a for supporting one end portion of the arm 5 and a male screw portion 52b having a sawtooth screw formed on the outer peripheral surface thereof. A cylindrical female screw member 53 that is screw-coupled to the support member 52 and a spring member 54 that urges the arm support member 52 in a direction to press the arm support member 52 against one end of the arm 5 are provided, and the male screw portion 52b of the arm support member 52 and Designed so that the sawtooth screw formed on the inner periphery of the female screw member 53 is locked when it receives a pressing load from the arm 5 and generates a sliding rotation by the biasing force of the spring member 54 when the pressing load is released. Has been. The female screw member 53 is fixed to the holding hole 6 a of the cylinder head 6.

  Therefore, when the valve is opened, the arm support member 52 that has received the pushing load from the arm 5 is pushed by the backlash of the screw, and then stops by locking the sawtooth screw. When the sawtooth screw is locked, a slight sliding rotation occurs, and this sliding rotation is caused by the backlash of the screw by the urging force of the spring member 54 when the arm support member 52 is released from the pushing load when the valve is closed. It is offset by sliding and rotating only after being pushed up. As a result, the valve operating mechanism can open the valve 2 with a constant valve lift by the arm 5 being supported by the pivot portion 52a of the arm support member 52 at a constant position.

  Further, when the valve clearance increases due to wear of the shaft end of the valve 2 or thermal expansion of the cylinder head 6, the arm support member 52 pushes up one end of the arm 5 until the clearance disappears due to the above-described sliding rotation when the valve is closed. Therefore, the clearance increase is absorbed immediately. On the other hand, when the valve clearance decreases due to thermal expansion of the valve 2 or wear of the valve seat 7, the arm support member 52 is prevented from moving axially at one end of the arm 5 until it is pushed up by the backlash of the screw when the valve is closed. Therefore, the clearance is gradually screwed into the female screw member 53 by the slight sliding rotation at the time of opening the valve, so that the clearance reduction is gradually absorbed. By these operations, the valve clearance of the valve operating mechanism is automatically adjusted.

  However, in the lash adjuster 51, when the pivot portion 52a of the arm support member 52 slides with one end portion of the arm 5 as the arm 5 swings, the arm support member 52 is not affected by the play between the two. The arm 5 may be rotated by receiving a rotational force. The rotation of the arm support member 52 is likely to occur particularly when the pushing load from the arm 5 is released. This is because when the arm support member 52 is not receiving a pressing load from the arm 5, the arm support member 52 can rotate relatively freely within the range of play with the female screw member 53.

Thus, when the arm support member 52 rotates regardless of its original function, the position where the pivot portion 52a supports the arm 5 becomes unstable, the valve lift amount of the valve mechanism becomes unstable, and the performance of the internal combustion engine deteriorates. May cause.
US Pat. No. 4,981,117 Japanese Utility Model Publication No. 4-44407

  An object of the present invention is to stabilize the valve lift amount of a valve mechanism incorporating a valve clearance automatic adjusting device using a sawtooth screw.

  As one means for solving the above-described problems, the present invention is incorporated in a valve operating mechanism that opens and closes a valve by swinging an arm that supports one end, and a pivot that supports one end of the arm. And an arm support member having a male screw portion screwed to the inner surface of the fixing member, and a spring member biasing the arm support member in a direction to press the arm support member against one end portion of the arm, the male screw portion of the arm support member, A valve clearance in which a female screw portion of the fixing member is locked when a pressing load is received from the arm, and a sawtooth screw is formed that causes a sliding rotation by the biasing force of the spring member when the pressing load is released. In the automatic adjustment device, the arm support member is divided into a pivot member having the pivot portion and a male screw member having the male screw portion. Than it is.

  That is, the arm support member is divided into a pivot member that supports one end of the arm of the valve mechanism and a male screw member that is screw-coupled to the inner surface of the fixed member, and the pivot member slides on one end of the arm. The rotation force received from the arm is absorbed by the slip between the pivot member and the male screw member and is not transmitted to the male screw member, thereby preventing the rotation of the male screw member unrelated to the original function, Stabilized the position of supporting the arm.

  In the above configuration, at least one of the contact surfaces of the pivot member and the male screw member is a convex spherical surface, thereby preventing uneven wear due to contact between the pivot member and the male screw member. The durability of can be improved. Here, if one contact surface is a convex spherical surface and the other is a concave spherical surface having the same radius of curvature as the convex spherical surface, the surface pressure between the contact surfaces of both members is reduced, and the durability of each member is improved. Further improve.

  Further, in the present invention, as another means for solving the above-mentioned problem, in the automatic valve clearance adjusting device, a configuration in which a low friction material is interposed between the pivot portion and one end portion of the arm is adopted. .

  That is, by interposing a low friction material between the pivot portion and one end portion of the arm and reducing the coefficient of friction between them, the rotational force received from the arm by the pivot portion is reduced, and the arm support member by this rotational force This makes it difficult to cause rotation and stabilizes the arm support position of the pivot portion. Here, if a hard carbon film is employed as the low friction material, the durability of the pivot portion can be improved.

  As described above, the valve clearance automatic adjusting device of the present invention divides the arm support member that supports one end of the arm of the valve operating mechanism into the pivot member and the male screw member, and the rotational force that the pivot member receives from the arm is reduced. Since the male screw member is not transmitted to the male screw member, the male screw member does not rotate regardless of its original function, and the arm support position of the pivot member is stable.

  In addition, instead of dividing the arm support member, even if a low friction material is interposed between the pivot portion and one end portion of the arm, the rotational force received by the pivot portion from the arm becomes small. The rotation of the member is less likely to occur, and the arm support position of the pivot portion is stabilized.

  Therefore, the valve operating mechanism incorporating any one of the above valve clearance automatic adjusting devices can always obtain a stable valve lift.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a swing arm type valve operating mechanism incorporating a lash adjuster 1 as a valve clearance automatic adjusting device of the first embodiment. The basic configuration and operation of this valve operating mechanism are the same as those shown in FIG. That is, in this valve operating mechanism, when the camshaft 3 rotates from the closed state of the valve 2 shown in FIG. 1 and pushes the central portion of the arm 5 with the cam 4, the arm 5 is supported at one end by the lash adjuster 1. By swinging and depressing the valve 2 at the other end, the valve 2 is separated from the valve seat 7 attached to the cylinder head 6 and is opened. When the cam 4 moves away from the arm 5, the valve 2 is pulled back by the force of the valve spring 8 and closed again.

  As shown in FIG. 2, the lash adjuster 1 incorporated in this valve operating mechanism is a male screw member in which a pivot member 9 that supports one end of the arm 5 and a sawtooth male screw portion 10a formed on the outer peripheral surface. 10, a cylindrical female screw member 12 that is screw-coupled to the male screw member 10, and a spring member 13 that biases the arm support member 11 in a direction in which the arm support member 11 is pressed against one end of the arm 5. Yes. A stopper 14 for retaining the pivot member 9 is fitted on the outer periphery of the upper end portion of the female screw member 12, and a bottom lid 15 for supporting the lower end of the spring member 13 is fitted on the outer periphery of the lower end portion. The female screw member 12 is embedded and fixed in the holding hole 6 a of the cylinder head 6.

  The pivot member 9 includes a pivot portion 9a that is slidably fitted into the recess 5a at one end of the arm 5, and a barrel portion 9b that is slidably fitted into the straight portion 12a on the inner periphery of the female screw member 12.

  The male screw member 10 is urged by a spring member 13 inserted into the hole 10b from the lower end side, and abuts the lower end plane of the pivot member body 9b at the upper end plane.

  The sawtooth screw formed on the male screw portion 10a of the male screw member 10 and the female screw portion 12b of the female screw member 12 has a flank angle on the pressure side flank surface that receives a pressing load transmitted from the arm 5 via the pivot member 9. It is formed larger than the flank angle of the sliding-side flank surface that receives the biasing force of the spring member 13, and locks when receiving a pressing load from the arm 5, and slips due to the biasing force of the spring member 13 when the pressing load is released. Rotation is generated.

  The lash adjuster 1 has the above-described configuration, and supports the arm 5 of the valve operating mechanism and adjusts the valve clearance by the same mechanism as the conventional one described above.

  That is, when the valve operating mechanism performs a valve opening operation, a pushing load is transmitted from one end of the arm 5 to the male screw member 10 via the pivot member 9. The male screw member 10 that has received the indentation load is pushed in as much as the backlash of the screw, contacts the female screw member 12 between the pressure side flank surfaces and slightly slides and rotates, and then locks and stops by the frictional force between the screw surfaces. . The pivot member 9 supports one end of the arm 5 in this state until the valve opening operation is completed.

  When the operation of the valve mechanism moves from opening to closing, the male screw member 10 released from the pushing load from the arm 5 is pushed up by the backlash of the screw by the urging force of the spring member 13, and the female screw member 12 and After contact between the sliding flank surfaces, it slides and rotates by an amount that cancels out the sliding rotation at the time of opening the valve, and pushes up the pivot member 9 to the position at the start of valve opening. Thereby, the pivot member 9 can always support the arm 5 at a fixed position.

  Further, when the valve clearance increases, the pivot member 9 pushes up one end of the arm 5 due to the sliding rotation of the male screw member 10 when the valve is closed to absorb the increased clearance, and when the valve clearance decreases, the male screw The member 10 does not slide and rotate when the valve is closed, but is gradually screwed into the female screw member 12 by a slight sliding rotation when the valve is opened, and the pivot member 9 is pushed into the female screw member 12 to absorb the clearance reduction. It has become.

  Furthermore, since the arm support member 11 is divided into the pivot member 9 and the male screw member 10, even if the pivot portion 9 a of the pivot member 9 slides with one end portion of the arm 5, The rotational force is absorbed by the slip between the pivot member 9 and the male screw member 10 and is not transmitted to the male screw member 10, so that the male screw member 10 does not rotate regardless of the original function described above.

  Therefore, in this lash adjuster 1, the arm 5 supporting position of the pivot member 9 is more stable than before, and the valve lift amount of the valve operating mechanism can be stabilized.

  FIG. 3 shows a modification of the contact surface shape of the pivot member and the male screw member. 3A is an example in which only the lower end surface of the pivot member 9 is a convex spherical surface, FIG. 3B is an example in which only the upper end surface of the male screw member 10 is a convex spherical surface, and FIG. 3C is a pivot member. 9 is an example in which both the lower end surface and the upper end surface of the male screw member 10 are convex spherical surfaces. FIG. 3D shows an example in which the lower end surface of the pivot member 9 is a convex spherical surface, and a concave spherical surface having the same radius of curvature as the convex spherical surface is formed on the upper end of the male screw member 10. In the example of FIG. 3 (e), the upper end surface of the male screw member 10 is a convex spherical surface and the lower end surface of the pivot member 9 is a concave spherical surface, contrary to the example of FIG. 3 (d). Although the shape of the bottom cover 15 and the method of attaching to the female screw member 12 are different from the example shown in FIGS. 1 and 2, the function of supporting the screw member 13 is the same.

  If each of these modifications is adopted, even if the pivot member 9 is slightly inclined due to a shift in the direction of the pushing load transmitted from the arm 5 to the pivot member 9 and the axial direction of the pivot member 9, the pivot member 9 and the male screw Since the member 10 does not come into contact with each other, uneven wear of the members 9 and 10 can be prevented, and durability can be improved. In particular, in the example of FIGS. 3D and 3E, the surface pressure between the contact surfaces of the members 9 and 10 is low, and the durability is excellent.

  FIG. 4 shows a second embodiment. A lash adjuster 16 as an automatic valve clearance adjusting device of this embodiment includes an arm support member 17 integrally formed with a pivot portion 17a for supporting one end of the arm 5 and a male screw portion 17b having a sawtooth screw on the outer peripheral surface. And an internal thread member 18 in which an internal thread portion 18a that is screw-coupled with the external thread portion 17b of the arm support member 17 is formed on the inner periphery of the upper half. In the arm support member 17, the lower end surface of the male screw portion 17b is urged by the spring member 19, and the pivot portion 17a is coated with a hard carbon film 20 called DLC (Diamond Like Carbon). The bottom lid 21 that supports the spring member 19 is fitted into the inner periphery of the lower end of the female screw member 18. The configuration and basic functions of the other parts are the same as those in the first embodiment.

  In this embodiment, since the hard carbon film 20 as a low friction material is coated on the pivot portion 17a of the arm support member 17, the friction coefficient between the pivot portion 17a and one end portion of the arm 5 is considerably smaller than that of the prior art. . For this reason, the rotational force received from the arm 5 when the pivot portion 17a slides on the arm 5 is small, and the arm support member 17 is unlikely to rotate unrelated to the original function. Therefore, as in the first embodiment, the arm 5 support position of the pivot portion 17a is stable, and the valve lift amount of the valve operating mechanism can be stabilized. On the other hand, since the arm support member 17 is rotated smoothly by its original function, the valve clearance can be adjusted more quickly and more reliably than before.

  In addition, covering the pivot portion 17a of the arm support member 17 with the hard carbon film 20 having higher hardness than the material steel and excellent wear resistance also leads to improvement in durability of the arm support member 17.

  In the example of FIG. 4, the hard carbon film 20 is coated on the pivot portion 17a. However, the hard carbon film 20 may be coated on the concave portion 5a at one end of the arm 5 serving as the counterpart side. In addition to the hard carbon film, hard chrome plating or the like can be employed as a low friction material that is interposed between the pivot portion and one end of the arm.

Front sectional view of the valve mechanism incorporating the lash adjuster of the first embodiment Front sectional view showing the lash adjuster of FIG. 1 in an enlarged manner a, b, c, d, and e are front sectional views showing modifications of the contact surface shape of the pivot member and male screw member of the lash adjuster in FIG. Front sectional view of the lash adjuster of the second embodiment Front sectional view of a valve mechanism incorporating a conventional lash adjuster

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 5 Arm 5a Recessed part 6 Cylinder head 6a Holding hole 9 Pivot member 9a Pivot part 9b Body part 10 Male thread member 10a Male thread part 11 Arm support member 12 Female thread member 12a Straight part 12b Female thread part 13 Spring member 16 Rush adjuster 17 Arm support Member 17a Pivot 17b Male thread 18 Female thread 18a Female thread 19 Spring member 20 Hard carbon film

Claims (5)

  An arm support member that is incorporated in a valve operating mechanism that opens and closes a valve by swinging an arm that is supported at one end, and that has a pivot portion that supports one end of the arm and a male screw that is screwed to the inner surface of the fixing member. And a spring member that urges the arm support member in a direction in which the arm support member is pressed against one end of the arm, and when the male screw portion of the arm support member and the female screw portion of the fixing member receive a pressing load from the arm. In the valve clearance automatic adjusting device formed with a sawtooth screw that is locked and generates sliding rotation by the biasing force of the spring member when the pushing load is released, the arm support member is pivoted with the pivot portion. An automatic valve clearance adjusting device, wherein the device is divided into a member and a male screw member having the male screw portion.   2. The valve clearance automatic adjusting device according to claim 1, wherein at least one of the contact surfaces of the pivot member and the male screw member is a convex spherical surface.   3. The valve according to claim 2, wherein one of the contact surfaces of the pivot member and the male screw member is a convex spherical surface, and the other is a concave spherical surface having the same radius of curvature as the convex spherical surface. Clearance automatic adjustment device.   An arm support member incorporated in a valve operating mechanism that opens and closes a valve by swinging an arm supported at one end, and having a pivot portion that supports the one end of the arm and a male screw that is screwed to the inner surface of the fixing member And a spring member that urges the arm support member in a direction in which the arm support member is pressed against one end of the arm, and when the male screw portion of the arm support member and the female screw portion of the fixing member receive a pressing load from the arm. In a valve clearance automatic adjusting device formed with a sawtooth screw that is locked and generates a sliding rotation due to the urging force of the spring member when the pushing load is released, between the pivot portion and one end portion of the arm. An automatic valve clearance adjusting device characterized by interposing a low friction material.   5. The automatic valve clearance adjusting device according to claim 4, wherein the low friction material is a hard carbon film.

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