JP2007205300A - Variable valve gear mechanism of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the axial position of the roller 41e of an input arm (cam hitting member) 41 in a variable valve gear mechanism 3 of an internal combustion engine 1. <P>SOLUTION: The input arm 41 comprises a roller 41e rotatably supported on a spindle 41d installed between a pair of opposed forks 41cL, 41cR and with which the outer peripheral surface of a cam lobe 17 is brought into contact. Position adjusting shims 7 for adjusting the axial position of the roller 41e are interposed between the roller 41e and the forks 41cL, 41cR. Consequently, the axial position of the roller 41e between the pair of forks 41cL, 41cR can be changed by properly setting the thickness of the positioning adjusting shims 7 disposed on both axial sides of the roller 41e. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism for varying an operating characteristic of at least one of an intake valve and an exhaust valve of an internal combustion engine.

  2. Description of the Related Art There is known a variable valve mechanism that varies operating characteristics such as valve lift and operating angle of intake valves and exhaust valves in accordance with the operating state of an internal combustion engine (see, for example, Patent Document 1).

  Such a variable valve mechanism has an intermediate drive mechanism disposed between the cam lobe of the camshaft and the valve, and this intermediate drive mechanism is an axis of the control shaft that is inserted into the central hole of the rocker shaft. The phase of the input part (cam striking member) and the swing cam (valve striking member) are relatively rotated by a slider gear driven in conjunction with the movement of the direction to change the valve lift amount. Is designed to be variable.

  By the way, when the intermediate drive mechanism is assembled to the cylinder head, it is necessary to adjust the valve lift and working angle by adjusting the initial relative position of the assembly comprising the input portion and the swing cam with respect to the slider gear. The adjustment work is cumbersome and difficult because it is necessary to disassemble the mediation drive mechanism.

  In order to facilitate such adjustment work, it is conceivable that a shim having a selected thickness is interposed between a support base on the cylinder head that supports the rocker shaft and the axially opposite of the assembly. (For example, refer to Patent Document 2).

The shim has a horseshoe shape so that it can be fitted to the rocker shaft from one position in the radial direction. In addition, in order to fix such a shim so that it cannot rotate, it is necessary to attach a holder separate from the shim to the support base and to lock the shim to the holder.
JP 2001-263015 A JP 2005-42641 A

  In the above-described conventional example, when the initial relative position of the assembly with respect to the slider gear is adjusted by selecting and assembling a shim having an appropriate thickness, the roller provided in the input section is a camshaft that is substantially stationary in the axial direction according to the adjustment amount. The position of the cam lobe is displaced in the axial direction.

  If the outer peripheral surface of the roller of the input unit comes into contact with the one end corner of the cam lobe in the axial direction along with such a position shift, an edge load acts on the roller of the input unit, It may cause uneven wear. In addition, if the assembly is rotated to change the operating characteristics of the valve with the position shifted, a moment load that impedes movement may be applied to the input section or the control shaft, which in turn opens and closes the valve. Could have a negative impact on

  An object of the present invention is to make it possible to adjust the axial position of a roller of a cam hit member in a variable valve mechanism for changing the operating characteristics of a valve of an internal combustion engine.

  Further, the present invention provides a variable valve mechanism for varying the operating characteristics of a valve of an internal combustion engine, in accordance with an initial position adjustment of an arm assembly with respect to a slider gear, The purpose is to enable correction even if the roller is displaced in the axial direction.

  The present invention is a variable valve mechanism that varies the operating characteristics of at least one of an intake valve and an exhaust valve of an internal combustion engine, and a rocker shaft fixedly supported in parallel to a camshaft on a support base on a cylinder head; A control shaft that is inserted into the central hole of the rocker shaft so as to be axially displaceable, a slider gear that is externally mounted on the rocker shaft so as to be interlocked with the control shaft, and a helical spline that is external to the slider gear; A cam hitting member that is swung by a cam lobe of the camshaft; and a valve hitting member that is externally mounted on a helical spline on the outer periphery of the slider gear and that pushes the valve. An outer peripheral surface of the cam lobe supported rotatably on a support shaft installed between opposing forks. It has a roller that contacts, between opposing this roller and the fork, position adjusting shim for adjusting the axial position of the roller is characterized in that it is interposed.

  According to this configuration, the axial position of the roller between the pair of forks can be changed by appropriately adjusting the thickness of the position adjusting shims disposed on both sides of the roller. Thereby, it is possible to arbitrarily adjust the axial position of the roller of the cam hit member relative to the cam lobe substantially stationary in the axial direction.

  At that time, if the axial position of the roller is set so that the outer peripheral surface of the cam hitting member is in contact with the outer peripheral surface of the cam lobe, no edge load is generated on the roller of the cam hitting member. As a result, the cam lobe and the roller of the cam hitting member are less likely to be unevenly worn, and the moment load that impedes the movement of the cam hitting member and the control shaft is eliminated, reducing the friction loss of the cam lobe. At the same time, the movement of the cam hit member is smoothed. For these reasons, it is advantageous for improving the fuel consumption and increasing the rotation speed of the internal combustion engine.

  Preferably, an initial adjustment shim for adjusting an initial relative position between the assembly and the slider gear is interposed between the assembly including the cam hitting member and the valve hitting member and the support table in the axial direction. Is done.

  According to this configuration, it is possible to adjust the initial relative position of the assembly comprising the cam hitting member and the valve hitting member with respect to the slider gear depending on the thickness of the initial adjustment shim. Is possible.

  In particular, when such initial adjustment is performed, the axial position of the cam hitting member changes in accordance with the adjustment amount. It will be displaced in the axial direction with respect to the cam lobe of the shaft. Even in such a case, if the axial position of the roller of the cam hit member is adjusted with the above-described position adjustment shim different from the shim for initial adjustment, the axial position of the roller of the cam hit member relative to the cam lobe is adjusted. It becomes possible to adjust.

  Preferably, a roller bearing is interposed between the support shaft of the cam hit member and the roller, and the position adjusting shim can receive both ends of the roller bearing in the axial direction. It is assumed.

  According to this configuration, the roller of the roller bearing rolls around the support shaft with the rotation of the roller of the cam hit member, and both axial ends of this roller come into contact with the position adjustment shim. There is no need to touch the fork.

  As a result, even if the fork is made of an uncured metal material, the roller subjected to the curing process becomes non-contact, so that wear of the fork is prevented.

  In other words, if the position adjustment shim is not used, if both ends in the axial direction of the roller come into contact with the inner surface of the fork as the roller rotates, the inner surface of the fork will wear over time. If the shim is attached, both ends of the roller in the axial direction come into contact with the inner surface of the position adjusting shim and do not come into contact with the fork, so that wear of the fork can be prevented.

  In addition, when the position adjustment shim wears over time, the position adjustment shim may be replaced with a new one. It is necessary to replace the whole, and the case where the position adjustment shim is used can be dealt with much easier and cheaper than the case where the position adjustment shim is not provided.

  Preferably, the position adjusting shim has a U-shaped notch that allows the cam hitting member to be fitted from one side in the radial direction.

  According to this configuration, the position adjustment shim can be attached to the support shaft after the variable valve mechanism is assembled to the internal combustion engine. It becomes possible to easily change the position adjustment shim.

  Preferably, the position adjusting shim is attached in such a direction that the U-shaped notch is opened toward the anti-cam lobe side.

  According to this configuration, since the roller and the support shaft are pressed to the opposite cam lobe side by the radial load input from the cam lobe, it is difficult for the position adjustment shim to come off from the support shaft to the cam lobe side. Thereby, the axial position of the roller of the cam hit member can be kept unchanged for a long time.

  According to the present invention, it is possible to adjust the axial position of the roller of the cam hit member with respect to the cam lobe substantially stationary in the axial direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 15 show an embodiment of the present invention.

  First, prior to the description of the characteristic configuration of the present invention, the configuration of a variable valve mechanism for an internal combustion engine which is a premise of the present invention will be described. Here, as shown in FIGS. 1 and 2, an example is given in which the variable valve mechanism 3 is attached to the intake valve 14 of an in-line four-cylinder DOHC engine as the internal combustion engine 1. The exhaust valve 15 can be similarly configured to be driven using the variable valve mechanism 3, but the description here is omitted for the sake of simplicity.

  The variable valve mechanism 3 can continuously change the valve lift amount and operating angle of the intake valve 14 and is disposed between the cam lobe 17 of the intake camshaft 16 and the roller rocker arm 24. Yes.

  One end of the roller rocker arm 24 is supported by the lash adjuster 25 and the other end is in contact with the tappet 14 a at the upper end of the intake valve 14.

  The variable valve mechanism 3 includes a rocker shaft 31, a control shaft 32, an actuator 33, and a valve lift mechanism 4.

  The rocker shaft 31 is immovable in the axial direction and the circumferential direction by a large number of partition walls (corresponding to a support base) 21 provided at regular intervals on the cylinder head 12 and a cam cap 22 attached to cover the partition wall 21. It is supported to become. The rocker shaft 31 is arranged in parallel with the intake camshaft 16 and the exhaust camshaft 18, that is, along the arrangement direction of the cylinders (combustion chambers 13).

  The control shaft 32 is inserted into the center hole of the rocker shaft 31 formed of a hollow pipe so as to be axially displaceable, and is driven forward and backward in the axial direction by the actuator 33.

  The number of valve lift mechanisms 4 is the same as the number of cylinders, and is externally mounted on the rocker shaft 31 so as to correspond to each cylinder. The valve lift mechanism 4 includes an input arm 41 as a cam hitting member, two output arms 42 and 42 as a valve hitting member, and a slider gear 43.

  The input arm 41 and the two output arms 42 and 42 are referred to as an arm assembly.

  The input arm 41 has a cylindrical housing 41 a, and a helical spline 41 b that meshes with the input-side helical spline 43 a of the slider gear 43 is formed on the inner peripheral surface thereof.

  In the input arm 41, a pair of forks 41cL and 41cR projecting radially outward is provided on the outer periphery of the housing 41a, and a support shaft parallel to the rocker shaft 31 is provided between the pair of forks 41cL and 41cR. A roller 41e is rotatably supported on the support shaft 41d through a plurality of rollers 41f as roller bearings. The roller 41f is shown only in FIG.

  The output arm 42 has a cylindrical housing 42 a, and a helical spline 42 b that meshes with the output-side helical spline 43 b of the slider gear 43 is formed on the inner peripheral surface thereof. On the outer periphery of the housing 42a of the output arm 42, a nose 42c protruding outward in the radial direction is provided. The nose 42c is formed in a substantially triangular shape in a side view, and has a cam surface 42d whose one side is curved in a concave shape.

  The slider gear 43 is externally mounted on the rocker shaft 31 so as to be movable in the axial direction in conjunction with the control shaft 32, and an input arm 41 and two output arms 42 are externally mounted on the outer diameter side thereof. The slider gear 43 is formed in a cylindrical shape having a through-hole 43c in the center, and an input side helical spline 43a that meshes with the helical spline 41b of the input arm 41 is formed in the middle in the axial direction on the outer periphery. On both sides in the axial direction, output-side helical splines 43b that mesh with the helical splines 42b of the output arm 42 are formed. The output side helical spline 43b has a smaller outer diameter than the input side helical spline 43a. The input-side helical spline 43a and the output-side helical spline 43b are formed so that the inclination directions of the teeth are opposite.

  The roller 41e of the input arm 41 is elastically biased so as to be always pressed against the cam lobe 17 by a lost motion spring 26 disposed in a compressed state on the cylinder head 12. The roller 24a of the roller rocker arm 24 is pressed against either the base circle portion of the housing 42a of the output arm 42 or the cam surface 42d of the nose 42c by the valve spring 14b of the intake valve 14. Due to such a relationship, the input arm 41 is swung by the rotation of the cam lobe 17, and the intake valve 14 is lifted via the roller rocker arm 24 by the output arm 42 swung integrally with the input arm 41. It has become.

  Here, the coupling form of the slider gear 43 to the rocker shaft 31 and the control shaft 32 will be described with reference to FIGS.

  In order to connect the slider gear 43 fitted to the rocker shaft 31 to the control shaft 32 in the rocker shaft 31 so as to be able to transmit power, the slider gear 43 has an inner circumferential groove 43d with a partial arc shape in a longitudinal section. A bushing 46 is provided.

  The bush 46 is formed with a pin insertion hole (through hole) 46 a in the middle in the circumferential direction, and is connected to the control shaft 32 via a connect pin 44.

  Specifically, the distal end portion of the connect pin 44 is inserted into the pin insertion hole 46 a of the bush 46, and the distal end portion of the connect pin 44 is inserted into the pin insertion hole 32 a of the control shaft 32. An intermediate portion of the connect pin 44 is inserted into the long hole 31 a of the rocker shaft 31.

  The slider gear 43 assembled in this way operates as follows.

  The control shaft 32 is movable in the axial direction with respect to the rocker shaft 31 within the range of the axial length of the long hole 31 a of the rocker shaft 31. Further, the slider gear 43 is fixed in the axial position with respect to the control shaft 32 by the engagement between the inner circumferential groove 43 d and the bush 46.

  Therefore, when the control shaft 32 is moved in the axial direction by driving the actuator 33, the operation is transmitted to the slider gear 43 via the connect pin 44 and the bush 46. As a result, the slider gear 43 moves in the axial direction in conjunction with the control shaft 32.

  In addition, since the bush 46 is movable in the circumferential direction in the inner circumferential groove 43d of the slider gear 43, the slider gear 43 is rotatable with respect to the control shaft 32 within the range. Thus, when the control shaft 32 is moved in the axial direction, the slider gear 43 rotates with respect to the control shaft 32 while moving in the axial direction.

  When the torque of the intake camshaft 16 is transmitted to the input arm 41, the torque is transmitted from the input arm 41 to the output arm 42 via the slider gear 43. At this time, the slider gear 43 is connected to the rocker shaft. Swing around 31.

  In such a valve lift mechanism 4, the slider gear 43 is moved in the axial direction together with the control shaft 32, and the relative position in the axial direction between the slider gear 43 and the arm assembly (input arm 41 and output arm 42) is changed. As a result, torsional forces in opposite directions are applied to the input arm 41 and the output arm 42. As a result, the input arm 41 and the output arm 42 rotate relative to each other, and the relative phase difference between the roller 41e of the input arm 41 and the nose 42c of the output arm 42 is changed.

  In the variable valve mechanism 3, the valve lift mechanism 4 for each cylinder is fixed to a common control shaft 32, so that all cylinders are moved along with the axial movement of the control shaft 32. The lift amount of the intake valve 14 is simultaneously changed.

  Next, the operation of the variable valve mechanism 3 will be described.

  As shown in FIG. 9A, when the base circle portion of the cam lobe 17 is in contact with the roller 41 e of the input arm 41, the roller 24 a of the roller rocker arm 24 is in contact with the base circle portion of the housing 42 a of the output arm 42. It is in a contact state. Therefore, the intake valve 14 is maintained in a state where the lift amount is “0” (a state where the intake port 12a is closed).

  When the roller 41e of the input arm 41 is pushed down through the lift portion of the cam lobe 17 with the clockwise rotation of the intake camshaft 16, the input arm 41 is counterclockwise with respect to the rocker shaft 31 as shown in FIG. It rotates in the turning direction (arrow A direction). As a result, the output arm 42 and the slider gear 43 rotate together.

  As a result, the cam surface 42d formed on the nose 42c of the output arm 42 contacts the roller 24a of the roller rocker arm 24, and the roller 24a is pushed down by the pressing of the cam surface 42d.

  As shown in FIG. 9B, when the roller 24a of the roller rocker arm 24 is pressed by the cam surface 42d, the roller rocker arm 24 swings around the contact portion with the lash adjuster 25, and the intake valve 14 is opened.

  In a state where the control shaft 32 moves to the maximum in the direction away from the actuator 33 (the direction of arrow F in FIG. 3), the roller 41e of the input arm 41 and the nose 42c of the output arm 42 around the axis of the rocker shaft 31 The relative phase difference of becomes the maximum.

  Thereby, when the cam lobe 17 pushes down the roller 41e to the maximum, the displacement difference of the roller 24a of the roller rocker arm 24 becomes the largest, and the intake valve 14 is opened and closed with the maximum valve lift amount and operating angle.

  As shown in FIG. 10A, when the base circle portion of the cam lobe 17 is in contact with the roller 41e of the input arm 41, the contact position between the output arm 42 and the roller 24a is maximized from the cam surface 42d. In a remote location. When the roller 41e of the input arm 41 is pushed down by the lift portion of the cam lobe 17 due to the rotation of the intake camshaft 16, the input arm 41 and the output arm 42 rotate together.

  However, in this case, since the contact position between the output arm 42 and the roller 24a is farthest from the cam surface 42d, the output arm until the pressing of the roller 24a of the roller rocker arm 24 by the cam surface 42d is started. The amount of rotation 42 becomes larger than that in the operating state shown in FIG. Further, when the roller 41e of the input arm 41 is pushed down through the lift portion of the cam lobe 17, the range of the cam surface 42d that comes into contact with the roller 24a is reduced to only a part of the base end side of the nose 42c. For this reason, the rocking amount of the roller rocker arm 24 corresponding to the pressing down of the roller 41e by the lift portion of the cam lobe 17 becomes small.

  As shown in FIG. 10B, the intake valve 14 is opened with a smaller valve lift amount due to the small swing amount of the roller rocker arm 24.

  Further, when the control shaft 32 is moved to the maximum in the direction approaching the actuator 33 (the arrow R direction in FIG. 3), the relative phase difference between the roller 41e and the nose 42c around the axis of the rocker shaft 31 is minimum. Become.

  As a result, the displacement amount of the roller 24a when the cam lobe 17 pushes the roller 41e down to the maximum is minimized, and the intake valve 14 is opened and closed with the minimum valve lift amount and operating angle.

  Here, the configuration of the embodiment to which the feature of the present invention is applied will be described with reference to FIGS.

  In short, the initial adjustment shims 5 and 5 are interposed between the support base composed of the partition wall 21 and the cam cap 22 and the arm assembly (the input arm 41 and the two output arms 42 and 42) in the axial direction. Position adjusting shims 7 and 7 are interposed between the rollers 41e of the input arm 41 and the pair of forks 41cL and 41cR facing each other in the axial direction.

  Specifically, first, the initial adjustment shim 5 will be described.

  In the first place, the variable valve mechanism 3 described above changes the valve lift amount by changing the relative position in the circumferential direction between the arm assembly (the input arm 41 and the two output arms 42 and 42) of the valve lift mechanism 4 and the slider gear 43. The valve operating angle is changed. At the initial assembly stage, the valve lift amount and the valve operating angle for each cylinder must be set to predetermined initial values.

  In order to adjust the initial values of the valve lift amount and the valve working angle, the arm assembly and the arm assembly are disposed by interposing an initial adjustment shim 5 as described below between each partition wall 21 and the arm assembly in the axial direction. This can be done by appropriately changing the initial relative position of the slider gear 43.

  As shown in FIGS. 11 and 12, the initial adjustment shim 5 is formed in a substantially L shape in side view by integrally forming a mounting piece 5b in a substantially orthogonal posture on a plate-like piece 5a.

  The plate-like piece 5a is appropriately set in thickness and is provided with a U-shaped notch 5c to form a bifurcated shape. The U-shaped notch 5c of the plate-shaped piece 5a is fitted into the rocker shaft 31 from one position in the radial direction, and the size of the opening and depth of the U-shaped notch 5c is the rocker shaft. It is formed corresponding to the outer diameter size of 31.

  The attachment piece 5b is for attaching and fixing to the cam cap 22, and a long hole 5d along the extending direction is provided so as to penetrate in the thickness direction. By attaching a fastening member such as a bolt 6 to the screw hole 22a of the cam cap 22 through the long hole 5d, the attachment piece 5b is fixedly attached to the cam cap 22. Further, the long hole 5d is useful for allowing fine adjustment of the relative position of the attachment piece 5b when attaching the attachment piece 5b to the cam cap 22.

  In the valve lift mechanism 4 for each cylinder, the thickness of the plate-like piece 5a of the initial adjustment shim 5 arranged on the left side of FIG. 12 and the plate-like piece of the initial adjustment shim 5 arranged on the right side of FIG. If the thickness of 5a is changed appropriately, the relative axial position and the relative circumferential position of the arm assembly and the slider gear 43 both change, so that the relative relationship between the input arm 41 and the output arm 42 of the arm assembly is changed. The phase difference is adjusted.

  Incidentally, as an example, if the plate-like piece 5a of the initial adjustment shim 5 arranged on the left side of FIG. 12 is thin and the plate-like piece 5a of the initial adjustment shim 5 arranged on the right side of FIG. Adjustable to the large lift side, conversely, the plate-like piece 5a of the initial adjustment shim 5 arranged on the left side of FIG. 12 is thick and the plate-like piece 5a of the initial adjustment shim 5 arranged on the right side of FIG. If the thickness is made thinner, it can be adjusted to the small lift side.

  By performing such adjustment using the initial adjustment shim 5 for each cylinder, the initial values of the valve lift amount and valve operating angle by the valve lift mechanism 4 disposed in all the cylinders can be made uniform. .

  Moreover, since the initial adjustment shim 5 can be attached and detached from one position in the radial direction of the rocker shaft 31 with the valve lift mechanism 4 assembled to the partition wall 21, a large number of initial thicknesses of the plate-like pieces 5a differ in advance. The adjustment shim 5 is prepared, and an optimum initial adjustment shim 5 can be selected from among the adjustment shims 5 and can be easily attached.

  Next, the position adjustment shim 7 will be described.

  When the above-described initial adjustment is performed, the roller 41e of the input arm 41 is displaced in the axial direction with respect to the cam lobe 17 of the intake camshaft 16 that is substantially stationary in the axial direction in accordance with the adjustment amount.

  Incidentally, for example, as shown in FIG. 13, when the internal combustion engine 1 is viewed in plan, the thickness X1 of the initial adjustment shim 5 on the left side in the drawing is increased, and the thickness X2 of the initial adjustment shim 5 on the right side in the drawing is set. When the thickness is reduced, the arm assembly is generally displaced to the right in the drawing, so that the axial center position P of the roller 41e of the input arm 41 is relative to the axial center position O of the cam lobe 17 of the intake camshaft 16. , The dimension Z is offset to the right side in the figure.

  If such a displacement causes the outer peripheral surface of the roller 41e of the input arm 41 to come into contact with one corner of the cam lobe 17 in the axial direction, an edge load is applied to the roller 41e of the input arm 41. Both of which can cause uneven wear. In addition, if the arm assembly is rotated to change the operating characteristics of the intake valve 14 with the position shifted, there is a risk that a load that impedes movement is applied to the input arm 41 or the control shaft 32. As a result, the opening / closing operation of the intake valve 14 may be adversely affected.

  In order to solve such a problem, in this embodiment, in the state shown in FIG. 13, a position adjusting shim 7 having an appropriate thickness is interposed between the pair of forks 41cL, 41cR and the roller 41e. Like to do.

  As shown in FIGS. 11 and 15, the position adjusting shim 7 is a substantially C-shaped plate as viewed from the side, and has a U-shaped notch 7a and a knob-shaped protrusion 7b. is doing.

  This position adjusting shim 7 has a U-shaped notch 7a fitted into the support shaft 41d from one radial direction, and the size of the opening and depth of the U-shaped notch 7a is supported. It is set corresponding to the outer diameter size of the shaft 41d. The knob-like protrusion 7b is intended to make it easier for an operator to hold and remove the position adjusting shim 7 between the pair of forks 41cL and 41cR and the roller 41e. To help.

  Then, when attaching the position adjusting shim 7, as shown in FIG. 15, the U-shaped notch 7a is opened toward the anti-cam lobe 17 side. By doing so, the roller 41e and the support shaft 41d are pressed toward the anti-cam lobe 17 side by the radial load input from the cam lobe 17, so that the position adjustment shim 7 is not easily detached from the support shaft 41d toward the cam lobe 17 side. As a result, the axial position of the roller 41e of the input arm 41 can be kept unchanged for a long time.

  Incidentally, in FIG. 12, if the position adjusting shim 7 on the left side in the figure is thin and the position adjusting shim 7 on the right side in the figure is thickened, the roller 41e can be displaced to the left side in the figure. If the middle left position adjusting shim 7 is thick and the right side position adjusting shim 7 is thin, the roller 41e can be displaced to the right side in the figure.

  Next, a procedure for adjusting the axial position of the roller 41e of the input arm 41 using the position adjusting shim 7 will be described.

  Specifically, an example in which correction is performed from the state shown in FIG. 13 as described above, that is, the state where the roller 41e is displaced is given. In the state shown in FIG. 13, the axial center position P of the roller 41 e of the input arm 41 is offset by the dimension Z on the right side in the figure with respect to the axial center position O of the cam lobe 17 of the intake camshaft 16.

  In order to correct such misalignment, as shown in FIG. 14, the thickness Y1 of the position adjusting shim 7 on the left side in the figure is reduced, and the thickness Y2 of the position adjusting shim 7 on the right side in the figure is increased. Accordingly, it is necessary to displace the roller 41e so as to be shifted to the left side in the drawing between the pair of forks 41cL and 41cR.

  If the thicknesses Y1, Y2 of the left and right position adjusting shims 7 are determined according to the offset dimension Z, the offset dimension Z can be made zero, and the axial center position of the roller 41e of the input arm 41 can be reduced. P can be made to coincide with the axial center position O of the cam lobe 17 of the intake camshaft 16.

  Thus, after adjusting the variation between cylinders of the valve lift mechanism 4 for each cylinder in the variable valve mechanism 3, the axial position of the roller 41e of the input arm 41 of the valve lift mechanism 4 for each cylinder and the intake camshaft 16 are adjusted. The positional deviation of the cam lobe 17 from the axial position can be corrected.

  By correcting the positional deviation in this way, the outer peripheral surface of the roller 41e of the input arm 41 can be brought into contact with the outer peripheral surface of the cam lobe 17, so that no edge load occurs on the roller 41e of the input arm 41. Therefore, the cam lobe 17 and the roller 41e of the input arm 41 are less likely to be unevenly worn, and the input arm 41 and the control shaft 32 are not subjected to a moment load that impedes movement, and the friction loss of the cam lobe 17 is reduced. In addition to being reduced, the movement of the input arm 41 is facilitated. For these reasons, it is advantageous for improving the fuel consumption and increasing the rotation speed of the internal combustion engine.

  Further, if the position adjusting shim 7 is interposed between the pair of forks 41cL, 41cR and the roller 41e, the following effects can be obtained.

  That is, as in the above-described embodiment, when a plurality of rollers 41f are interposed between the support shaft 41d and the roller 41e in the input arm 41, if the position adjustment shim 7 is eliminated, the roller 41e is rotated. Accordingly, both ends of the roller 41f in the axial direction come into contact with the inner surfaces of the forks 41cL and 41cR, so that the inner surfaces of the forks 41cL and 41cR wear with time. If the position adjusting shim 7 is attached, the rollers 41f Since both ends in the axial direction are in contact with the inner surface of the position adjusting shim 7 and are not in contact with the forks 41cL and 41cR, wear of the forks 41cL and 41cR can be prevented.

  When the position adjustment shim 7 is worn over time, the position adjustment shim 7 may be replaced with a new one. However, when the position adjustment shim 7 is not used, the forks 41cL and 41cR are worn over time. Accordingly, it is necessary to replace the entire input arm 41, and the present invention using the position adjustment shim 7 can deal with it much more easily and cheaply than the case where the position adjustment shim 7 is not used.

  Incidentally, when the input arm 41 is manufactured by sintering and molding an appropriate metal powder, if the entire input arm 41 is cured by an appropriate heat treatment, thermal distortion occurs in the helical spline 41b provided on the inner periphery thereof. In consideration of the decrease in shape accuracy and dimensional accuracy, heat treatment is often not performed. On the other hand, the roller 41f is generally cured by an appropriate heat treatment. For these reasons, it is preferable to prevent the forks 41cL and 41cR from being worn by making the relatively hard rollers 41f non-contact with the relatively soft forks 41cL and 41cR.

  By the way, in this embodiment, since the position adjusting shim 7 has a C-shape, it is considered that the roller 41f cannot be received at the open portion, and thus it is considered that the wear of the forks 41cL and 41cR cannot be prevented. There is no problem for the following reasons.

  In other words, when the roller 41e of the input arm 41 is pressed by the cam lobe 17 of the intake camshaft 16, the roller 41e is configured to roll and support via the roller 41f. Therefore, the roller 41e and the support shaft 41d are generally used. On the other hand, the radial load from the cam lobe 17 acts on the angle θ range as shown in FIG.

  The angle θ that becomes the load load range is generally about 60 to 90 degrees, and a predetermined number of rollers 41f located in the load load range bear the radial load. Therefore, even if the roller 41f that bears the radial load is displaced in the axial direction, both ends in the axial direction come into sliding contact with the forks 41cL and 41cR, but the forks 41cL and 41cR wear due to the axial load at that time. The range is an area corresponding to the load application area.

  For such a situation, the C-shaped position adjusting shim 7 is mounted on the support shaft 41d in the state shown in FIG. The axial load from the roller 41f located can be received. From this, it becomes possible to reliably prevent the forks 41cL and 41cR from being worn by the rollers 41f located in the load-loading zone.

  Moreover, if the roller 41f located in the open portion of the position adjusting shim 7 among the rollers 41f located in the area other than the load-loading area is displaced in the axial direction, it is not received by the position adjusting shim 7, Although it may abut against the forks 41cL and 41cR, it can be said that the forks 41cL and 41cR are less likely to be worn because the axial load by these rollers 41f is slight.

  As for the initial adjustment shim 5 and the position adjustment shim 7 described above, for example, resin molding using a material obtained by press-molding a band-shaped metal plate or a material obtained by mixing an appropriate engineering plastic or an appropriate reinforcing fiber. Product. However, for the position adjusting shim 7, it is preferable to select a hard material or a material excellent in self-lubricity in consideration of wear resistance.

It is a top view showing typically an internal-combustion engine provided with a variable valve mechanism concerning the present invention. It is an arrow view of the (2)-(2) line cross section of FIG. It is a perspective view of the variable valve mechanism of FIG. It is a disassembled perspective view of the valve lift mechanism of FIG. It is a perspective view which decomposes | disassembles and shows the slider gear and rocker shaft of the valve lift mechanism of FIG. It is a perspective view which fractures | ruptures and shows the upper half of the valve lift mechanism of FIG. FIG. 5 is a cross-sectional view showing a connecting portion of a slider gear to the rocker shaft and control shaft of FIG. 4. FIG. 8 is a cross-sectional view taken along line (8)-(8) in FIG. 7. FIG. 3 is a side view used for explaining the operation when the relative phase difference between the input arm and the output arm in FIG. 2 is maximized. FIG. 3 is a side view used for explaining the operation when the relative phase difference between the input arm and the output arm in FIG. 2 is minimized. It is a perspective view which shows the state which isolate | separated each shim in the valve lift mechanism of FIG. It is an arrow view of the (12)-(12) line cross section of FIG. It is a figure which shows the state which the roller of the input arm shifted in the axial direction by the initial adjustment in FIG. It is a figure which shows the state which correct | amended the axial direction position shift of the roller of the input arm shown in FIG. 13 with the position adjustment shim. It is a figure which shows the state which looked at the input arm single-piece | unit in FIG. 12 from the side surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 12 Cylinder head 14 Intake valve 16 Intake camshaft 17 Cam rib 21 Partition (support stand)
22 Cam cap (support)
3 Variable valve mechanism 31 Rocker shaft 32 Control shaft 4 Valve lift mechanism 41 Input arm (cam hitting member)
42 Output arm (valve striking member)
43 Slider gear 5 Initial adjustment shim 7 Position adjustment shim 7a U-shaped notch

Claims (5)

A variable valve mechanism that varies the operating characteristics of at least one of an intake valve and an exhaust valve of an internal combustion engine,
A rocker shaft fixed and supported in parallel to the camshaft on a support base on the cylinder head, a control shaft inserted through the central hole of the rocker shaft so as to be axially displaceable, and interlocked with the control shaft. An externally mounted slider gear, a cam hitting member which is externally mounted on a helical spline on the outer periphery of the slider gear, and which is swung by a cam lobe on the camshaft; an externally mounted helical spline on the outer periphery of the slider gear; Including a valve striking member that pushes,
The cam hit member includes a roller rotatably supported by a support shaft installed between a pair of opposing forks, and an outer peripheral surface of the cam lobe is in contact with the roller and the fork. A variable valve mechanism for an internal combustion engine, wherein a position adjusting shim for adjusting the axial position of the roller is interposed therebetween.   2. An initial adjustment shim for adjusting an initial relative position between the assembly and the slider gear between axially opposing the assembly including the cam hitting member and the valve hitting member and the support base according to claim 1. A variable valve mechanism for an internal combustion engine, characterized by being interposed.   3. The roller bearing according to claim 1 or 2, wherein a roller bearing is interposed between the support shaft of the cam hit member and the roller, and the position adjusting shim receives both axial ends of the roller of the roller bearing. A variable valve mechanism for an internal combustion engine characterized in that   4. The internal combustion engine according to claim 1, wherein the position adjusting shim has a U-shaped notch that allows the cam hitting member to be fitted from one position in the radial direction. Variable valve mechanism.   5. The variable valve mechanism for an internal combustion engine according to claim 4, wherein the position adjusting shim is attached in such a direction that the U-shaped notch is opened toward the anti-cam lobe side.

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