JP4988429B2 - Rush adjuster - Google Patents

Description

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

  As a valve operating device that operates a valve provided on the intake port or exhaust port of an engine, an arm type that moves the valve stem connected to the valve at the swing end of the arm that swings according to the rotation of the cam A valve operating device 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. Further, due to wear of the sliding portion of the valve operating device, a gap may be generated between the constituent members of the valve operating device (for example, between the valve and the valve seat), and compression leakage may occur due to the clearance.

  Therefore, in order to absorb the gaps between the constituent members of the valve operating device, a lash adjuster is often built into the swinging end of the arm, and the relative position between the arm and the valve stem is automatically adjusted by the lash adjuster.

  As such a lash adjuster, an accommodation hole penetrating vertically is formed at the swinging end portion of the arm, and a cylindrical nut member whose both upper and lower ends are fitted into the accommodation hole is formed at the lower end of the nut member. The flanged part is brought into contact with the lower surface of the arm, the upper end of the nut member protrudes from the upper surface of the arm, and a bottomed cylindrical cap is fixed to the upper end of the nut member to prevent the nut member from coming out of the receiving hole. A male screw that engages a flat surface formed on the outer periphery of the flange portion with a flat surface formed on the arm to prevent the nut member from rotating and engages with a female screw formed on the inner periphery of the nut member. Is provided on the outer periphery, and the screw rod is biased downward by a spring incorporated between the upper end surface of the screw rod and the bottom of the cap, and the screw rod Lash adjuster in which the lower end surface so as to abut against the valve stem is known (Patent Document 1).

  In this lash adjuster, when the valve stem is pushed down by the rotation of the cam, an axial force acts on the screw rod, but the male screw on the outer periphery of the screw rod is received by the female screw of the nut member. Is fixed. When the relative position of the arm and the valve stem changes due to thermal expansion of the valve operating device, the screw rod moves in the axial direction while rotating in the nut member according to the change in position, and the valve operating device The gap between the constituent members is adjusted.

  By the way, the arm type valve gear is formed of an aluminum alloy to reduce the weight of the arm. Further, the lash adjuster ensures the wear resistance of the portion engaged with the screw rod by screwing the nut member made of steel.

Here, the steel nut member has a greater specific gravity than the aluminum alloy arm, so if the volume of the nut member is large, the weight of the swing end of the arm increases, and when the arm swings, The arm is elastically deformed by the inertial force acting on the nut member, and the deformation may cause a deviation in the valve operation. Particularly, in the case of a sports type engine, the arm swings at a high speed in a high rotation region, so that the inertial force acting on the nut member is large, and the valve operation is likely to shift due to the deformation of the arm.
JP 2006-132426 A

  However, the lash adjuster is provided with a flange portion at the lower end of the nut member in order to receive an axial force acting on the nut member when the valve stem is pushed down by rotation of the cam. In addition, in order to attach a cap for preventing removal from the accommodation hole, the upper end of the nut member protrudes from the upper surface of the arm, and the length of the nut member is long. For this reason, this lash adjuster has a large weight of the nut member and may not be compatible with a high-speed engine.

  The problem to be solved by the present invention is to provide a lash adjuster that is small in weight and is compatible with a high-speed engine.

  In order to solve the above problems, a bottomed housing hole is opened on the lower surface of the rocking end of an aluminum alloy arm that rocks according to the rotation of the cam, and the upper side has a small diameter on the inner periphery of the housing hole. A stepped portion is provided, and a cylindrical steel nut member whose upper and lower ends are both open in the accommodation hole is fitted into the accommodation portion so that the upper end surface of the nut member is brought into contact with the stepped portion. A retaining portion for retaining from the inner periphery of the lower end of the accommodation hole, and a screw rod having a male screw on the outer periphery that engages with a female screw formed on the inner periphery of the nut member, and an upper end surface of the screw rod, The lash adjuster employs a configuration in which a screw rod is urged downward by a spring incorporated between the bottom surface of the housing hole and the lower end surface of the screw rod is brought into contact with the valve stem of the valve gear.

This lash adjuster can have the following configuration.
1) A convex portion is formed on the inner periphery of the lower end of the accommodation hole by caulking the lower end edge of the accommodation hole, and the retaining portion is constituted by the convex portion.
2) The retaining portion is constituted by a retaining ring attached to the inner periphery of the lower end of the accommodation hole.

When the configuration 1) is added, the following configuration can be further added.
1) A plurality of concave portions are formed in the outer periphery of the lower end of the nut member at intervals in the circumferential direction, and the nut member is prevented from rotating by allowing the convex portions to enter the concave portions.
2) A plurality of convex portions are formed on the outer periphery of the nut member at intervals in the circumferential direction, and a concave portion that fits into the convex portion is formed on the inner periphery of the accommodation hole, and the convex portion and the concave portion are fitted. To prevent the nut member from rotating.

  In addition, a plurality of convex portions are formed on the upper end surface of the nut member at intervals in the circumferential direction, a concave portion that fits the convex portion is formed in the stepped portion, and the convex portion and the concave portion are fitted to each other. The nut member can also be prevented from rotating.

  In the lash adjuster according to the present invention, the upper end surface of the nut member is brought into contact with the inner peripheral step portion of the accommodation hole, and the step portion receives the axial force acting on the nut member. There is no need to provide a flange portion. Further, since the nut member is prevented from coming off by the retaining portion provided on the inner periphery of the lower end of the accommodation hole, it is not necessary to project the upper end of the nut member from the upper surface of the arm, and the length of the nut member is short. Therefore, this lash adjuster has a small weight of the nut member and can be used for a high-speed engine.

  FIG. 1 shows a valve gear incorporating a lash adjuster 1 according to a first embodiment of the present invention. This valve operating apparatus has 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 7 that swings in response to rotation of a cam 6. .

  The valve stem 5 extends upward from the valve 4 and slidably penetrates the cylinder head 2. An annular spring retainer 8 is fixed to the upper outer periphery of the valve stem 5, and a valve spring 9 is incorporated between the lower surface of the spring retainer 8 and the upper surface of the cylinder head 2. The valve spring 9 urges the valve stem 5 upward via the spring retainer 8, and the valve 4 is seated on the valve seat 10 by the urging force.

  The arm 7 is made of an aluminum alloy, and a central portion 7B is supported by a support shaft 11, and can swing around the support shaft 11. A roller 12 that contacts the cam 6 is attached to one swinging end 7A of the arm 7, and the lash adjuster 1 is incorporated into the other swinging end 7C.

  The cam 6 is fixed to the camshaft 13, and when the camshaft 13 rotates, the cam crest 6 b raised with respect to the base circle 6 a pushes up the swinging end 7 </ b> A of the arm 7 via the roller 12, The other swinging end 7C of the arm 7 is lowered.

  A bottomed accommodation hole 14 is opened on the lower surface of the swing end portion 7 </ b> C of the arm 7, and the lash adjuster 1 is incorporated in the accommodation hole 14. As shown in FIG. 2, the lash adjuster 1 includes a nut member 15, a screw rod 16, a spring 17, and a spring seat 18.

  The nut member 15 is made of a steel material, is fitted into the accommodation hole 14, and is formed in a cylindrical shape whose both upper and lower ends are open. The upper end surface of the nut member 15 is in contact with a step portion 19 having a small diameter on the upper side formed in the inner periphery of the accommodation hole 14. Further, a convex portion 20 is formed on the inner periphery of the lower end of the accommodation hole 14 by caulking the lower edge of the accommodation hole 14, and the nut member 15 is prevented from coming off by the convex portion 20. Further, as shown in FIG. 3 and FIG. 4, the convex portion 20 enters a concave portion 21 formed at a circumferential interval in the outer periphery of the lower end of the nut member 15, thereby preventing the nut member 15 from rotating. Has been.

  A male screw 22 is formed on the outer periphery of the screw rod 16, and the male screw 22 is engaged with a female screw 23 formed on the inner periphery of the nut member 15. The male screw 22 and the female screw 23 are formed in a sawtooth shape having an asymmetric cross section along the axis, and pressure side flank 24 that receives pressure when a force in a direction of pushing the screw rod 16 into the nut member 15 is applied. Is larger than the flank angle of the play side flank 25. An oil film exclusion groove 26 is formed in the pressure side flank 24 of the screw rod 16 along the thread. The male screw 22 and the oil film exclusion groove 26 can be formed simultaneously, for example, by rolling.

  As shown in FIG. 2, the spring 17 is incorporated between the upper end surface of the screw rod 16 and the bottom surface 27 of the accommodation hole 14, and biases the screw rod 16 downward via the spring seat 18. The lower end surface of the screw rod 16 is in contact with the upper end surface of the valve stem 5.

  Next, an operation example of the lash adjuster 1 will be described.

  When the camshaft 13 rotates and the cam 6 pushes up the swing end portion 7A of the arm 7, the other swing end portion 7C of the arm 7 descends, the screw rod 16 pushes down the valve stem 5, and the valve 4 The intake port 3 opens away from the valve seat 10. At this time, axial force acts on the screw rod 16, but the pressure side flank 24 of the male screw 22 is received by the pressure side flank 24 of the female screw 23, so that the axial position of the screw rod 16 is fixed.

  Further, when the camshaft 13 rotates and the cam crest 6b passes the position of the roller 12, the valve stem 5 is raised by the urging force of the valve spring 9, the valve 4 comes into contact with the valve seat 10, and the intake port 3 closes.

  Further, during the operation of the engine, due to the difference in thermal expansion that occurs between the components of the valve operating device such as the cylinder head 2, the valve stem 5, and the arm 7, the swing end 7C of the arm 7 and the upper end surface of the valve stem 5 When the distance between them increases, the screw rod 16 gradually moves downward by the urging force of the spring 17, so that no gap is generated between the lower end surface of the screw rod 16 and the upper end surface of the valve stem 5.

  On the contrary, when the contact surface between the valve 4 and the valve seat 10 is worn and the distance between the swinging end portion 7C of the arm 7 and the upper end surface of the valve stem 5 is reduced, the base circle 6a of the cam 6 is Even when in contact with the roller 12, no gap is generated between the lower end surface of the screw rod 16 and the upper end surface of the valve stem 5. Therefore, when the cam crest 6b of the cam 6 passes the position of the roller 12, a slight slip occurs between the male screw 22 and the female screw 23, the slip is accumulated, and the screw rod 16 gradually moves upward. In addition, there is no gap between the contact surfaces of the valve 4 and the valve seat 10.

  The lash adjuster 1 receives the axial force acting on the nut member 15 at the inner peripheral step portion 19 of the accommodation hole 14 when the valve stem 5 is pushed down by the rotation of the cam 6. There is no need to provide the abutting flange portion at the lower end of the nut member 15. Further, since the nut member 15 is prevented from coming off by the convex portion 20 provided at the inner periphery of the lower end of the accommodation hole 14, it is not necessary to project the upper end of the nut member 15 from the upper surface of the arm 7, and the length of the nut member 15. Is short. Therefore, the lash adjuster 1 has a smaller weight than the nut member 15 provided with a flange portion at the lower end of the nut member 15 and can be used for a high-speed engine.

  In the lash adjuster 1, the lubricating oil existing between the pressure side flanks 24, 24 is oil film when the pressure side flank 24 of the female screw 23 of the nut member 15 receives the pressure side flank 24 of the male screw 22 of the screw rod 16. Since it escapes into the exclusion groove 26, an oil film due to the squeeze effect is hardly formed between the pressure side flank 24, 24. Therefore, the axial force acting on the screw rod 16 can be quickly received by the female screw 23 of the nut member 15 even at a low temperature when the viscosity of the lubricating oil is large.

  FIG. 5 shows a lash adjuster 31 according to the second embodiment of the present invention. Hereinafter, parts corresponding to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The nut member 32 fitted in the accommodation hole 14 is made of a steel material, and is formed in a cylindrical shape in which both upper and lower ends are open. The upper end surface of the nut member 32 is in contact with a step portion 33 having a small diameter on the upper side formed in the inner periphery of the accommodation hole 14. Further, as shown in FIGS. 6 to 8, a plurality of convex portions 34 are formed on the upper end surface of the nut member 32 at intervals in the circumferential direction, and the convex portions 34 are formed on the stepped portion 33. The nut member 32 is prevented from rotating by fitting into the recessed portion 35 formed by the fitting.

  As shown in FIG. 5, a circumferential groove 36 is formed in the inner periphery of the lower end of the accommodation hole 14, and the nut member 32 is prevented from coming off by a retaining ring 37 attached to the circumferential groove 36. .

  Similarly to the first embodiment, the lash adjuster 31 receives the axial force acting on the nut member 32 when the valve stem 5 is pushed down by the step portion 33 on the inner periphery of the accommodation hole 14. There is no need to provide a flange at the lower end. Further, since the nut member 32 is prevented from coming off by the retaining ring 37 provided on the inner periphery of the lower end of the accommodation hole 14, it is not necessary to project the upper end of the nut member 32 from the upper surface of the arm 7, and the length of the nut member 32 Is short. Therefore, the lash adjuster 31 has a small weight of the nut member 32 and can be used for a high-speed engine.

  FIG. 9 shows a lash adjuster 41 according to the third embodiment of the present invention. Hereinafter, parts corresponding to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The nut member 42 fitted in the accommodation hole 14 is made of a steel material, and is formed in a cylindrical shape whose upper and lower ends are both open. The upper end surface of the nut member 42 is in contact with a stepped portion 43 formed on the inner periphery of the accommodation hole 14 and having a small diameter on the upper side. Further, as shown in FIG. 10, a plurality of convex portions 44 are formed on the upper end surface of the nut member 42 at intervals in the circumferential direction, and the convex portions 44 are concave portions formed in the stepped portion 43. 45, and the nut member 42 is prevented from rotating by the fitting.

  A convex portion 46 is formed on the inner periphery of the lower end of the accommodation hole 14 by caulking the lower edge of the accommodation hole 14, and the nut member 42 is prevented from coming off by the convex portion 46. Moreover, the convex part 46 has entered into the concave part 47 formed in the outer periphery of the lower end of the nut member 42 at intervals in the circumferential direction, whereby the nut member 42 is prevented from rotating.

  Similarly to the first embodiment, the lash adjuster 41 receives the axial force acting on the nut member 42 when the valve stem 5 is pushed down by the step portion 43 on the inner periphery of the accommodation hole 14. There is no need to provide a flange at the lower end. Further, since the nut member 42 is prevented from coming off by the convex portion 46 provided on the inner periphery of the lower end of the accommodation hole 14, it is not necessary to project the upper end of the nut member 42 from the upper surface of the arm 7, and the length of the nut member 42. Is short. Therefore, the lash adjuster 41 has a small weight of the nut member 42 and can be used for a high-speed engine.

  Further, when compared with the lash adjuster 1 of the first embodiment, the lash adjuster 41 is prevented from rotating with respect to the accommodation hole 14 at the upper and lower ends of the nut member 42, so that the convex portion 46 formed by caulking The acting load is small and it is more durable.

  FIG. 11 shows a lash adjuster 51 according to the fourth embodiment of the present invention. Hereinafter, parts corresponding to those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  The nut member 52 fitted in the accommodation hole 14 is made of a steel material, and is formed in a cylindrical shape whose upper and lower ends are both open. The upper end surface of the nut member 52 is in contact with the step portion 19 formed on the inner periphery of the accommodation hole 14. Further, as shown in FIG. 12, a plurality of convex portions 53 are formed on the outer periphery of the nut member 52 at intervals in the circumferential direction, and the convex portions 53 are formed on the inner periphery of the accommodation hole 14. And the nut member 52 is prevented from rotating by the fitting.

  A convex portion 55 is formed on the inner periphery of the lower end of the accommodation hole 14 by caulking the lower end edge of the accommodation hole 14, and the nut member 52 is prevented from coming off by the convex portion 55.

  Similarly to the first embodiment, the lash adjuster 51 receives the axial force acting on the nut member 52 when the valve stem 5 is pushed down by the step portion 19 on the inner periphery of the accommodation hole 14. There is no need to provide a flange at the lower end. Further, since the nut member 52 is prevented from coming off by the convex portion 55 provided on the inner periphery of the lower end of the accommodation hole 14, there is no need to project the upper end of the nut member 52 from the upper surface of the arm 7, and the length of the nut member 52. Is short. Therefore, the lash adjuster 51 has a small weight of the nut member 52 and can correspond to a high-speed engine.

The front view which shows the valve operating apparatus incorporating the lash adjuster of 1st Embodiment of this invention Enlarged sectional view of the lash adjuster shown in FIG. Sectional view along line III-III in FIG. The perspective view which shows the state which extracted the nut member shown in FIG. 2 from the accommodation hole The expanded sectional view which shows the lash adjuster of 2nd Embodiment of this invention Fig. 5 is an enlarged cross-sectional view near the upper end of the nut member. Sectional drawing along the VII-VII line of FIG. The perspective view which shows the state which extracted the nut member shown in FIG. 5 from the accommodation hole The expanded sectional view which shows the lash adjuster of 3rd Embodiment of this invention The perspective view which shows the state which extracted the nut member shown in FIG. 9 from the accommodation hole The expanded sectional view which shows the lash adjuster of 4th Embodiment of this invention Sectional drawing along the XII-XII line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rush adjuster 5 Valve stem 6 Cam 7 Arm 7C Oscillating end part 14 Accommodating hole 15 Nut member 16 Screw rod 17 Spring 19 Step part 20 Convex part 21 Concave part 22 Male screw 23 Female screw 27 Bottom face 31 Rush adjuster 32 Nut member 33 Step part 34 Convex part 35 Concave part 37 Retaining ring 41 Rush adjuster 42 Nut member 43 Step part 44 Convex part 45 Concave part 46 Convex part 47 Concave part 51 Rush adjuster 52 Nut member 53 Convex part 54 Concave part 55 Convex part

Claims (4)

A bottomed receiving hole (14) is opened on the lower surface of the swing end (7C) of the aluminum alloy arm (7) that swings according to the rotation of the cam (6). A step portion (19) having a small diameter on the inner periphery is provided, and a cylindrical steel nut member (15) whose upper and lower ends are both open is fitted in the accommodation hole (14), and a nut member (15 ) Is brought into contact with the stepped portion (19), and a retaining portion (20) for retaining the nut member (15) from the accommodating hole (14) is provided on the inner periphery of the lower end of the accommodating hole (14). A screw rod (16) having a male screw (22) on the outer periphery thereof that is engaged with a female screw (23) formed on the inner periphery of the nut member (15), and an upper end surface of the screw rod (16); A spring (17) incorporated between the bottom surface (27) of the receiving hole (14) Urges the Cru rod (16) downward, and the lower end surface of the screw rod (16) so as to abut against the valve stem (5) of the valve gear,
A lash adjuster in which a convex portion (20) is formed on the inner periphery of the lower end of the accommodating hole (14) by caulking the lower end edge of the accommodating hole, and the retaining portion is constituted by the convex portion (20). A plurality of recesses (21) are formed on the outer periphery of the lower end of the nut member (15) at intervals in the circumferential direction, and the protrusions (20) are inserted into the recesses (21), whereby the nut member (15 The lash adjuster according to claim 1 , wherein A plurality of convex portions (53) are formed on the outer periphery of the nut member (52) at intervals in the circumferential direction, and a concave portion (54) fitted to the convex portion (53) is formed in the accommodating hole (14). The lash adjuster according to claim 1 , wherein the nut member (52) is prevented from rotating by being formed on a circumference and fitting the convex portion (53) and the concave portion (54). A plurality of convex portions (34) are formed on the upper end surface of the nut member (32) at intervals in the circumferential direction, and a concave portion (35) fitted to the convex portion (34) is formed in the stepped portion (33). The lash adjuster according to claim 1 , wherein the lash adjuster is formed and the nut member (32) is prevented from rotating by fitting the convex portion (34) and the concave portion (35).

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