JP2013096338A - Rocker arm with valve clearance automatic adjusting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve followability during high-speed rotation by reducing the weight of an arm end, and to simplify handling during assembling in a rocker arm having a lash adjuster function part in one end, which automatically adjusts valve clearance by axially moving an adjust screw while rotating it by a load of torsion torque of a torsion coil spring.SOLUTION: In the end of the arm 3 swingable around a rocker shaft 2, the torsion coil spring 26, and the adjust screw 24 automatically adjusting the valve clearance by axially moving while rotating by the torsion torque from the torsion coil spring 26, are arranged. A screw hole 21, with which the adjust screw 24 is screw-engaged, is directly formed in the one end of the arm 3 to reduce weight by thinning the arm end, thereby improving the followability. A straight hole 22 is formed on the upper side of the screw hole 21, and the torsion coil spring 26 is housed in the straight hole 22, thereby simplifying the handling during the arm assembling.

Description

  The present invention relates to a rocker arm having a function of automatically adjusting a valve clearance of an arm type valve gear in an internal combustion engine.

  As 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, an arm is swingably supported around a rocker shaft provided above the engine. An arm type is known in which one end of an arm is pushed up by rotation of a cam and a valve stem is pushed down at the other end of the arm to open the valve.

  In the above-mentioned arm type valve gear, if the valve clearance is formed due to mechanical and thermal influences, the valve lift will change and the valve cannot be opened and closed accurately. Has been done.

  As a device for automatically correcting the valve clearance, there is an oil supply type lash adjuster. However, since the oil supply type lash adjuster uses engine oil as a working fluid, the oil supply type lash adjuster is easily affected by a change in hydraulic pressure due to the engine speed, contamination contained in the oil, or bubbles. In addition, the structure is complicated, requiring a lot of man-hours for manufacturing and assembly, which is disadvantageous in terms of cost.

  In order to solve such a problem, the inventor of the present invention disclosed in Patent Document 1 an arm type valve that incorporates a mechanical lash adjuster in the end of the arm and automatically corrects the valve clearance by the lash adjuster. A device has already been proposed.

  Here, in the lash adjuster described in Patent Document 1, a serrated female screw is formed on the inner periphery of a cylindrical body, and the serrated male screw formed on the outer periphery of the adjusting screw is screw-engaged with the female screw. Then, the torsion torque of the torsion coil spring is applied to the adjusting screw, and the adjusting screw is moved in a direction protruding from the opening end of the body while rotating.

  In addition, in the arm type valve operating apparatus described in Patent Document 1, a fitting hole penetrating vertically is provided at the end of an arm that can swing around a rocker shaft, and the inside of the fitting hole is formed from below. In the state where the body of the lash adjuster is inserted and the flange provided at the lower end of the body is in contact with the lower surface of the end of the arm, the wave spring is formed at the upper end protruding upward from the upper end opening of the fitting hole. And a retaining ring is attached on the wave spring to prevent the lash adjuster from being pulled out.

  By the way, in the above lash adjuster in which the female screw of the body and the male screw of the adjustment screw have a sawtooth shape, the elastic force of the compression coil spring is applied to the adjustment screw, so that the adjustment screw rotates and moves in the axial direction. However, in this case, backlash occurs between the pressure side flank on the opposite side of the adjusting screw in the screw engaging part of the female screw and the male screw, and the adjusting screw is loaded with the pressing force from the cam. Every time it is done, it will move backward by the amount corresponding to backlash. For this reason, if the thread surface is worn, the backlash increases, and a desired valve lift amount may not be obtained.

  However, in the lash adjuster described in Patent Document 1, a torsion torque is applied to the adjustment screw using a torsion coil spring. Therefore, in the screw engaging portion of the male screw and the female screw, the adjustment screw is moved in the direction of travel. A backlash occurs between a certain play-side flank, and even if the pressure from the cam is applied to the adjustment screw, the adjustment screw does not move backward. For this reason, even if a thread surface wears, it has the characteristic that a desired valve lift amount can be obtained reliably.

JP 2011-127533 A

  By the way, in the above-mentioned arm type valve gear, since the internal thread in which the male screw of the adjusting screw is screw-engaged is formed on the inner periphery of the cylindrical body inserted into the fitting hole of the arm, the weight of the arm end portion However, the followability due to the high-speed rotation of the cam is poor, and there are points to be improved in improving the followability.

  In addition, since the torsion coil spring that applies torsional torque to the adjusting screw is exposed on the end of the arm, the torsion coil spring having relatively low strength is attached to the engine when the arm is assembled to the arm type valve gear. It is difficult to handle because it may be deformed by coming into contact with other surrounding parts and structures, or may fall off, and there are still points to be improved in terms of facilitating the handling.

  Here, as shown in Japanese Examined Patent Publication No. Sho 62-33401, when a screw hole is formed at the end of the arm, and the male screw on the outer periphery of the screw rod is screw-engaged with the female screw on the inner periphery of the screw hole. Although it is possible to reduce the weight of the end of the arm, in the valve clearance adjusting device described in the above publication, since the adjustment screw is pressed in the axial direction by a leaf spring provided on the arm, Even the ease of handling when assembling the arm cannot be improved.

  An object of the present invention is to provide a rocker arm having at one end a lash adjuster function portion that automatically adjusts a valve clearance by rotating an adjusting screw in an axial direction while rotating an adjustment screw by a torsional torque load of a torsion coil spring. It is intended to improve the followability at high-speed rotation by reducing the weight and to facilitate the handling at the time of assembly to the valve gear.

  In order to solve the above problems, in the present invention, one end is pushed up by rotation of the cam and swings around the rocker shaft, and the valve stem is pushed down at the other end to open the valve. A screw hole that opens at the lower surface of the end portion, and a straight hole that opens at the upper surface of the end portion of the arm above the screw hole. A male screw formed on the outer periphery of the adjusting screw is screw-engaged with a female screw formed on the inner periphery of the screw hole, a torsion coil spring is incorporated in the straight hole, and an upper end portion of the torsion coil spring is connected to the arm, The lower end is connected to the upper part of the adjusting screw, and the adjusting screw is applied with a torsional torque in the direction of moving from the lower end opening of the screw hole while the adjusting screw rotates. Than it was adopted with the structure load to.

  As described above, by forming the screw hole into which the male screw of the adjusting screw is screw-engaged at one end of the arm, it is possible to reduce the weight of the one end of the arm, and by the high-speed rotation of the cam. A rocker arm with good followability can be obtained.

  Also, by incorporating the torsion coil spring into the straight hole formed at the end of the arm, the torsion coil spring contacts other parts around the engine when the rocker arm is assembled to the valve gear. This eliminates the need for easy handling when assembling the arm.

  Here, when the inner diameter of the straight hole formed on the upper side of the screw hole is larger than the inner diameter of the screw hole, the screw hole can be processed by a tap, and the screw hole can be easily formed.

  Also, if the outer diameter of the torsion coil spring is smaller than the inner diameter of the straight hole and larger than the inner diameter of the screw hole, the torsion coil spring should be installed in the straight hole when assembling the lash adjuster function that automatically adjusts backlash. By dropping from above, the torsion coil spring is received at the step portion formed at the boundary position between the straight hole and the screw hole, so that assembly can be facilitated.

  Furthermore, a square winding part is provided at each of the upper and lower ends of the torsion coil spring, and the upper winding part is fitted to the rectangular tube part at the lower end part of the cap member fixed in the upper opening end part of the straight hole. By fitting the lower winding part to the square shaft part provided on the upper part of the adjustment screw, the connection of the torsion coil spring to the arm and the adjustment screw can be made a connection by fitting. It can be easily connected to the arm and the adjusting screw.

  In the rocker arm according to the present invention, when the winding direction of the torsion coil spring is reversed with respect to the winding direction of the male screw formed on the outer periphery of the adjustment screw, when the torsion coil spring is twisted, the upper and lower winding portions Is tightly wound around the rectangular tube portion of the cap member and the angular shaft portion of the adjusting screw, and a torsional torque can be reliably applied to the adjusting screw.

  In addition, the torsion coil spring reduces the diameter of the cylindrical coil portion at the center due to the torsion applied. For this reason, the gap between the outer diameter of the torsion coil spring and the inner diameter surface of the straight hole can be set small in a no-load state before the twist is applied. Thus, when the torsion coil spring is inserted into the straight hole, the torsion coil spring is prevented from being tilted by being guided by the inner diameter surface of the straight hole, and the lower winding portion is connected to the angular shaft portion of the adjustment screw. While being able to make it fit reliably, the square cylinder part of a cap can be reliably fitted to an upper winding part, and automation of an assembly can be enabled.

  Here, the following assembly method can be employed for assembling the lash adjuster function unit. That is, with the adjustment screw screwed in from the lower end opening of the screw hole, and the adjustment screw screwed in to the deepest position, the torsion coil spring is inserted from the upper opening of the straight hole, and the lower winding part is adjusted. The screw is fitted to the square shaft portion, the square tube portion of the cap member is fitted to the upper winding portion of the torsion coil spring, the cap member is rotated, and a torsional force of a predetermined magnitude is applied to the torsion coil spring. In the state, the cap member is press-fitted into the upper opening of the straight hole.

  In the assembly method as described above, the free length of the torsion coil spring is set so that the lower winding portion is fitted to the angular shaft portion of the adjustment screw screwed to the deepest position in the screw hole. By setting the length of the upper portion to be located above the upper end surface of the arm, it is possible to reliably apply a torsional force due to the rotation of the cap member, and to facilitate the assembly.

  When the cap member is attached by press fitting, a cylindrical portion is provided on the cap member. At this time, by forming a notch portion that opens at the upper end surface of the cylindrical portion, it is not necessary to manage the press-fitting allowance with high accuracy, making it easy to process and obtaining a stable pressure input. Can do. Further, if an outward flange is provided at the upper end of the cylindrical portion, the press-fitting amount can be managed by the contact of the flange with the upper end surface of the arm.

  In the present invention, as described above, the screw hole into which the male screw of the adjustment screw is screw-engaged is formed directly at one end of the arm, so that the end of the arm can be thinned and the weight can be reduced. In addition, a rocker arm having good followability by high-speed rotation of the cam can be obtained.

  Further, by incorporating the torsion coil spring into a straight hole formed at one end of the arm, the torsion coil spring comes into contact with other parts around the engine when the rocker arm is assembled to the valve gear. There is no problem, and handling can be facilitated.

Longitudinal sectional view of an arm type valve gear adopting a rocker arm according to the present invention Sectional drawing which expands and shows the incorporating part of the lash adjuster function part of FIG. Plan view of FIG. Sectional view along line IV-IV in FIG. Sectional view along line VV in FIG. Sectional drawing which shows the state in the middle of assembly of a lash adjuster function part

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an arm type valve gear. In this arm type valve operating apparatus, a rocker shaft 2 disposed on the upper side of the cylinder head 1 supports the central portion in the length direction of the arm 3 and pushes up one end of the arm 3 by the rotation of the cam 4 to lock the rocker shaft. The arm 3 is swung around 2 and the valve stem 5 is pushed down at the other end of the arm 3 to open the valve 6.

  Here, the valve stem 5 has a spring retainer 7 at the upper end, and the valve stem 5 is attached in a direction in which the lower end valve 6 is in close contact with the valve seat 9 by the pressing force of the valve spring 8 loaded on the spring retainer 7. It is energized.

  1 shows the OHV engine in which one end of the arm 3 is pushed up by the rotation of the cam 4 via the tappet 10 and the push rod 11, but the one end of the arm 3 is pushed up directly by the cam 4. It may be an OHC engine.

  As shown in FIG. 2, a mechanical lash adjuster function unit 20 that automatically adjusts the valve clearance is provided in one end of the arm 3.

  The lash adjuster function unit 20 is formed with a screw hole 21 opened at one end of the arm 3 at one end of the arm 3 and a straight hole 22 opened at the upper surface of one end of the arm 3 above the arm 3. A male screw 25 on the outer periphery of the adjustment screw 24 is screw-engaged with a female screw 23 formed on the inner periphery, and a torsion torque of a torsion coil spring 26 incorporated in the straight hole 22 is applied to the adjustment screw 24 to adjust the screw. The adjusting screw 24 is urged in a direction of moving downward from the lower end opening of the screw hole 21 while rotating 24, and a spherical portion 27 provided at the lower end of the adjusting screw 24 is formed on the upper surface of the push rod 11. The spherical seat 28 is pressed against.

  Here, the female screw 23 formed on the inner periphery of the screw hole 21 and the male screw 25 formed on the outer periphery of the adjusting screw 24 have the flank angle of the pressure side flank 29 that receives the pushing force from the cam 4 as the play side flank 30. The sawtooth screw has a larger lead angle than the flank angle, and is provided with a lead angle that moves in the axial direction while the adjusting screw 24 is rotated by the torsion torque of the torsion coil spring 26.

  The female screw 23 and the male screw 25 are not limited to serrated screws, and may be trapezoidal screws or triangular screws.

  An inner diameter of the straight hole 22 is larger than an inner diameter of the screw hole 21, and a step surface 31 is provided at a boundary position between the straight hole 22 and the screw hole 21.

  In order to apply the torsion torque of the torsion coil spring 26 to the adjustment screw 24, it is necessary to connect the upper end portion of the torsion coil spring 26 to the arm 3 and connect the lower end portion to the adjustment screw 24. Therefore, in the embodiment, as shown in FIGS. 2, 4 and 5, square winding portions 32a and 32b are provided at both upper and lower ends of the torsion coil spring 26, and the upper winding portion 32a is formed as a straight hole. 22 is fitted into a rectangular tube portion 34 at the lower end of the cap member 33 attached to the open end portion of the opening 22, and the lower winding portion 32 b is fitted into a rectangular shaft portion 35 provided at the upper end portion of the adjusting screw 24. .

  Here, in order to fix the cap member 33 to the arm 3, a cylindrical portion 36 is provided in the cap member 33, and the cylindrical portion 36 is press-fitted into the upper opening end of the straight hole 22. Further, in order to restrict the press-fitting amount, an outward flange 37 is provided at the upper end of the cylindrical portion 36, and the outward flange 37 is abutted against the upper surface of one end portion of the arm 3.

  As shown in FIGS. 2 and 3, if the notch 38 extending from the outer periphery of the outward flange 37 to the upper part of the cylindrical portion 36 is formed, it is not necessary to manage the press-fitting allowance with high accuracy, and stable pressure input is possible. Can be obtained.

  As shown in FIG. 6, the torsion coil spring 26 has an outer diameter smaller than the inner diameter of the straight hole 22 and larger than the inner diameter of the screw hole 21. The winding direction of the torsion coil spring 26 is reverse to the winding direction of the male screw 25 formed on the outer periphery of the adjusting screw 24.

  Further, the free length L of the torsion coil spring 26 is such that the adjustment screw 24 screwed into the screw hole 21 is screwed to the deepest position, and the lower winding portion 32b is fitted to the upper angular shaft portion 35. In this state, the upper part is set to a length that is located above the upper surface of one end of the arm 3. Here, the adjustment screw 24 is screwed to the deepest position. The adjustment screw 24 is screwed to a position where the flange 39 provided at the lower end of the adjustment screw 24 abuts the lower surface of one end of the arm 3. It means the state that was.

  When assembling the lash adjuster function portion 20 having the above-described configuration, the adjustment screw 24 is screwed from the lower end opening of the screw hole 21, and the flange 39 provided at the lower end portion of the adjustment screw 24 is as shown in FIG. In a state of being screwed to the deepest position where it abuts the lower surface of one end of the arm 3, the torsion coil spring 26 is inserted from the upper opening of the straight hole 22, and the lower winding portion 32 b is inserted into the angular axis of the adjusting screw 24. The torsion coil spring 26 is fitted to the upper winding part 32 a of the torsion coil spring 26, the square tube part 34 of the cap member 33 is fitted, the cap member 33 is rotated, and the torsion coil spring 26 has a predetermined amount of torsional force. In such a state, the cap member 33 is press-fitted into the upper opening of the straight hole 22.

  In the assembly as described above, the free length L of the torsion coil spring 26 is such that the lower winding portion 32b is fitted to the angular shaft portion 35 of the adjusting screw 24 screwed to the innermost position in the screw hole 21. In this state, the length of the upper portion is located above the upper surface of the one end of the arm 3, so that the rectangular tube portion 34 of the cap member 33 can be easily fitted to the upper winding portion 32 a of the torsion coil spring 26. The torsion coil spring 26 can be reliably loaded with a torsional force by the rotation of the cap member 33.

  The assembly of the lash adjuster function unit 20 is not limited to the above method. For example, with the adjustment screw 24 screwed in a predetermined amount, the lower winding portion 32b of the torsion coil spring 26 is fitted to the upper angular shaft portion 35, and the rectangular tube portion 34 of the cap member 33 of the upper winding portion 32a. And the adjustment screw 24 may be screwed in a state where the cap member 33 is press-fitted into the upper opening of the straight hole 22 to apply a torsional force to the torsion coil spring 26.

  The arm 3 is assembled to the valve gear after the lash adjuster function unit 20 is assembled. At the time of the assembling, the arm 3 is assembled by holding the adjusting screw 24 in the pushed state, and after the assembling, the pushing and holding of the adjusting screw 24 is released. As a result of the release, the adjusting screw 24 descends while rotating due to the torsional torque load of the torsion coil spring 26, and the spherical portion 27 at the lower end presses the spherical seat 28 formed on the upper surface of the push rod 11, thereby reducing the valve clearance. The state is adjusted automatically.

  In assembling the arm 3 to the valve gear as described above, the torsion coil spring 26 that applies torsional torque to the adjusting screw 24 is housed in the straight hole 22, so that contact with other parts is not possible. And easy to handle.

  In an operation state in which the engine is driven in the assembled state of the arm 3 incorporating the lash adjuster function unit 20 and the valve 6 is opened and closed by the rotation of the cam 4, the valve stem 5 and the arm 3 are separated by thermal expansion of the cylinder head 1. When the valve clearance is generated between the end portions, the adjustment screw 24 moves downward along the pressure side flank 29 due to the torsion torque applied to the adjustment screw 24 from the torsion coil spring 26.

  At this time, since the adjusting screw 24 is in contact with the push rod 11 and is non-movable support, one end of the arm 3 is lifted, and the arm 3 swings to the center of the rocker shaft 2 and the valve clearance. To absorb.

  Further, when the adjusting screw 24 receives a pushing force from the valve stem 5 via the arm 3, the pushing force is supported by the pressure side flank 29 that is pressed against each other, and the adjusting screw 24 is immersed in the screw hole 21 while rotating. It is prevented from moving in the direction.

  On the other hand, when the distance between the cam 4 and the lower end of the adjusting screw 24 is reduced due to wear of the valve seat 9 or the like, the adjusting screw 24 is gradually pushed in by the axially varying load applied from the push rod 11 and rotates. It moves in the direction (upward direction) to be immersed in the screw hole 21 and prevents the valve 6 from being incompletely closed when the valve 4 is closed when the base circle 4a of the cam 4 contacts the tappet 10. At this time, the adjusting screw 24 is pushed to a position where the minimum value of the fluctuating load in the axial direction becomes 0, and does not move back further.

  The arm 3 incorporating the lash adjuster function unit 20 that automatically adjusts the valve clearance swings around the rocker shaft 2 as the cam 4 rotates. At this time, at one end of the arm 3, the screw hole 21 into which the male screw 25 of the adjustment screw 24 is screw-engaged is directly formed in the arm 3 and is thin. Swing motions follow the rotation well.

2 Rocker shaft 3 Arm 4 Cam 21 Screw hole 22 Straight hole 23 Female screw 24 Adjust screw 25 Male screw 26 Torsion coil spring 31 Step surface 32a Winding portion 32b Winding portion 33 Cap member 34 Square tube portion 35 Square shaft portion 36 Cylindrical portion 37 Outward flange 38 Notch

Claims (9)

  One end is pushed up by the rotation of the cam and swings around the rocker shaft, and the other end has a swingable arm that pushes down the valve stem to open the valve. Provided at the end with a screw hole that opens on the bottom surface of the end and a straight hole that opens on the top surface of the end of the arm above the screw hole, and the adjustment screw is attached to the female screw formed on the inner periphery of the screw hole. A male screw formed on the outer periphery is screw-engaged, a torsion coil spring is incorporated in the straight hole, an upper end portion of the torsion coil spring is connected to an arm, and a lower end portion is connected to an upper portion of the adjustment screw. A valve with an automatic valve clearance adjustment function that applies torsional torque to the adjusting screw in the direction of moving from the lower end opening of the screw hole while the screw rotates. Kaamu.   The rocker arm with a valve clearance automatic adjustment function according to claim 1, wherein an inner diameter of the straight hole is larger than an inner diameter of the screw hole.   The rocker arm with a valve clearance automatic adjustment function according to claim 2, wherein the outer diameter of the torsion coil spring is smaller than the inner diameter of the straight hole and larger than the inner diameter of the screw hole.   A square winding part is provided at each of the upper and lower ends of the torsion coil spring, and the upper winding part is fitted to the square tube part at the lower end part of the cap member fixed in the upper opening end part of the straight hole. The valve clearance automatic adjustment according to any one of claims 1 to 3, wherein the connection is made to the arm, and the lower winding portion is fitted to a square shaft portion provided on the upper part of the adjusting screw to be connected to the adjusting screw. Rocker arm with function.   The rocker arm with a valve clearance automatic adjustment function according to any one of claims 1 to 4, wherein a winding direction of the torsion coil spring is reversely wound with respect to a winding direction of a male screw formed on an outer periphery of an adjustment screw.   The free length of the torsion coil spring is such that the upper part is located above the upper surface of the end of the arm in a state where the lower winding part is fitted to the angular shaft part of the adjusting screw most pushed into the screw hole. The rocker arm with a valve clearance automatic adjustment function according to claim 4 or 5, wherein the rocker arm has a length.   The rocker arm with a valve clearance automatic adjustment function according to any one of claims 4 to 6, wherein a cylindrical portion is provided on an upper portion of the cap member, and the cylindrical portion is press-fitted into an opening end portion of the straight hole.   The rocker arm with a valve clearance automatic adjustment function according to claim 7, wherein the cylindrical portion has a cutout portion opened at an upper end surface of the cylindrical portion.   The rocker arm with a valve clearance automatic adjustment function according to claim 7 or 8, wherein the cylindrical portion has an outward flange at an upper end.

Images