JP2008240626A - Valve train of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a lubricating state between a cam lobe and a cam-follower further suitable, in a variable valve train using a rocking cam. <P>SOLUTION: This variable valve train has the rocking cam 6, a curved surface tappet 18 interposed between the rocking cam 6 and a valve 20, and oil feeding mechanisms 22, 23 and 24, and changes a radius of curvature to a negative from a positive and again to the positive from the negative as a sliding surface 6b with the curved surface tappet 18 of the rocking cam 6 goes away from a base circle. The oil feeding mechanisms 22, 23 and 24 supply lubricating oil between the rocking cam 6 and the curved surface tappet 18 in a predetermined period before a PV value between the rocking cam 6 and the curved surface tapped 18 becomes maximum. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lubrication mechanism for a variable valve mechanism, and more particularly to a lubrication mechanism for a variable mechanism capable of continuously expanding and reducing the lift amount and operating angle of a valve using a swing cam.

In order to continuously expand and reduce the lift amount and operating angle of a valve, for example, as disclosed in Patent Document 1, a variable valve mechanism using a swing cam instead of a conventional rotary cam is known. Yes.
JP 2004-204822 A

  By the way, in general, the lubrication between the cam lobe and the cam follower is performed by a method of dripping lubricating oil from a delivery pipe provided on the upper part of the cylinder head. Since the direction is reversed and the cam lobe sliding surface jumps upward, the method of dripping from above hinders entrainment of the lubricating oil, and there is a problem that sufficient lubrication cannot be achieved.

  Moreover, the appearance form of the peak of the PV value (P: surface pressure, V: sliding speed) is different between the valve system using the swing cam and the conventional valve system using the normal rotating cam. Specifically, in the case of a rotating cam, a peak appears only once after the end of the positive valve lift acceleration period during the valve opening operation, whereas in the case of a swing cam, after the end of the ramp period of the cam, Peaks appear at two locations after the end of the positive acceleration interval. For this reason, when using a swing cam, it is necessary to make the lubrication state between the cam lobe and the cam follower more suitable than when using a conventional rotating cam.

  However, Patent Document 1 does not describe any lubrication between the cam lobe and the cam follower.

  Therefore, an object of the present invention is to make the lubrication state between the cam lobe and the cam follower more suitable in a variable valve mechanism using a swing cam.

  The valve operating mechanism of the internal combustion engine of the present invention includes a swing cam, a curved tappet interposed between the swing cam and the valve, and an oil supply mechanism for supplying lubricating oil to the swing cam and the curved tappet. In the variable valve mechanism, the radius of curvature changes from positive to negative and from negative to positive again as the sliding surface of the rocking cam with the tappet moves away from the base circle. Supplies lubricating oil between the swing cam and the curved tappet before the PV value between the swing cam and the curved tappet is maximized.

  According to the present invention, since the lubricating oil can be reliably supplied between the cam lobe and the cam follower before the PV value reaches the maximum value, the lubrication state can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram of a swing cam drive portion of a valve mechanism that can variably control the lift amount and operating angle of a valve used in this embodiment, and is attached to a cylinder head (not shown). Provided. FIG. 2 is a schematic diagram (seen from the engine front side) of the intake valve driving portion of the valve operating mechanism.

  The lift amount here means the maximum lift amount. Further, the variable control of the lift amount means that the maximum lift amount is variably controlled, and excludes the lift amount change when opening and closing in synchronization with the rotation of the crankshaft.

  The valve operating mechanism includes a lift / working angle variable mechanism 13 that changes the lift / working angle of the intake valve 20 and a phase variable mechanism 12 that advances or retards the phase of the center angle of the lift (phase with respect to the crankshaft). And are combined.

  The lift / operating angle variable mechanism 13 has been previously proposed by the applicant of the present invention and is known together with the phase variable mechanism 12 in Japanese Patent Application Laid-Open No. 2002-89303 and Japanese Patent Application Laid-Open No. 2002-89341. Only the outline will be described.

  The variable lift / operating angle mechanism 13 includes a hollow drive shaft (oscillation shaft) 1 rotatably supported by a cam bracket (not shown) above the cylinder head, and a drive fixed to the drive shaft 1 by press fitting or the like. An eccentric cam 2 as a cam, a control shaft 7 rotatably supported by the same cam bracket at a position above the drive shaft 1 and arranged in parallel with the drive shaft 1, and an eccentric cam portion 8 of the control shaft 7 And a valve follower 19 as a curved tappet that abuts against the upper end of each intake valve 20 and is swingable about a pivot 21 as a fulcrum. A valve driving rocker arm (hereinafter simply referred to as a rocker arm) 17 provided, and a swing cam 6 that opens and closes the intake valve 20 via the rocker arm 17 are provided. The variable valve rocker arm 4 has one end portion connected to the upper end portion of the link arm 3 as a ring-shaped link via a connecting pin 10 and the other end portion connected to a connecting pin 9. And connected to the upper end of the link member 5 as a rod-shaped link. The lower end portion of the link member 5 is connected to the swing cam 6 via a connecting pin 11.

  As will be described later, the drive shaft 1 is driven by a crankshaft of an engine via a timing chain or a timing belt.

  The eccentric cam 2 has a circular outer peripheral surface, and the center of the outer peripheral surface is offset from the shaft center of the drive shaft 1 by a predetermined amount, and the annular portion 3a of the link arm 3 is rotatable on the outer peripheral surface. Is fitted.

  The variable valve rocker arm 4 has a substantially central portion through which the eccentric cam portion 8 is rotatable. The eccentric cam portion 8 is eccentric from the axial center of the control shaft 7, and accordingly, the rocking center of the variable valve rocker arm 4 changes according to the angular position of the control shaft 7.

  The oscillating cam 6 is rotatably supported on the outer periphery of the drive shaft 1 via a sleeve-like member 25 described later, and near the end extending in the direction perpendicular to the axial direction of the drive shaft 1. As described above, the lower end portion of the link member 5 is connected via the connecting pin 11. On the lower surface of the swing cam 6, a base circle surface 6c that forms a concentric arc with the drive shaft 1, and a cam lobe as a sliding surface extending from the base circle surface 6c to the end portion in a predetermined curve. The base surface 6c and the cam lobe slide surface 6b are in contact with the curved cam follower 18 according to the swing position of the swing cam 6. It has become.

  That is, the base circle surface 6c is a section where the lift amount becomes zero as a base circle section. When the swing cam 6 swings and the cam lobe sliding surface 6b contacts the cam follower 18, the rocker arm 17 pivots 21. As a fulcrum, the intake valve 20 gradually lifts. A slight ramp section is provided between the base circle section and the lift section.

  As shown in FIG. 1, the control shaft 7 is configured to rotate within a predetermined angle range by a lift / operation angle control hydraulic actuator 14 provided at one end. The hydraulic pressure supply to the lift / operating angle control hydraulic actuator 14 is controlled based on a control signal from an engine control unit (not shown).

  The operation of the lift / operating angle variable mechanism 13 will be described. When the drive shaft 1 rotates, the link arm 3 moves up and down by the cam action of the eccentric cam 2, and accordingly, the variable valve rocker arm 4 swings around the control shaft 7 as a swing shaft. The swing of the variable valve rocker arm 4 is transmitted to the swing cam 6 via the link member 5, and the swing cam 6 swings. Due to the cam action of the swing cam 6, the cam follower 18 is pressed, the rocker arm 17 is tilted, and the intake valve 20 is lifted.

  Here, when the angle of the control shaft 7 is changed via the lift / operating angle control hydraulic actuator 14, the swing center position of the variable valve rocker arm 4 is changed, and as a result, the initial swing position of the swing cam 6. Changes.

  For example, if the eccentric cam portion 8 is positioned upward, the variable valve rocker arm 4 is positioned upward as a whole, and the connecting pin 11 is relatively lifted upward. That is, the initial swing position of the swing cam 6 is inclined in a direction in which the cam lobe sliding surface 6 b is separated from the cam follower 18. Therefore, when the swing cam 6 swings with the rotation of the drive shaft 1, the base circle surface 6c continues to contact the cam follower 18 for a long time, and the period during which the cam lobe sliding surface 6b contacts the cam follower 18 is short. For this reason, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle of the cam is also reduced.

  Conversely, assuming that the eccentric cam portion 8 is positioned downward, the variable valve rocker arm 4 is positioned downward as a whole, and the end portion of the swing cam 6 is pushed downward relatively. Become. That is, the initial swing position of the swing cam 6 is inclined in a direction in which the cam lobe sliding surface 6 b approaches the cam follower 18. Therefore, when the swing cam 6 swings as the drive shaft 1 rotates, the portion that contacts the cam follower 18 immediately shifts from the base circle surface 6c to the cam lobe sliding surface 6b. For this reason, the lift amount is increased as a whole, and the operating angle is also increased.

  Since the initial position of the eccentric cam portion 8 can be continuously changed, the valve lift characteristic is continuously changed accordingly. That is, the lift and the operating angle can be expanded and contracted simultaneously and continuously. In this embodiment, as the lift / operating angle changes, the intermediate angle does not change and the opening timing and closing timing of the intake valve 20 change substantially symmetrically.

  As shown in FIG. 1, the phase variable mechanism 12 relatively rotates the sprocket 15 provided at the front end portion of the drive shaft 1 and the sprocket 15 and the drive shaft 1 within a predetermined angle range. And a phase control actuator 16. The sprocket 15 rotates in synchronization with the crankshaft via a timing chain or timing belt (not shown). The phase control actuator 16 is controlled based on a control signal from an engine control unit (not shown). The control of the phase control actuator 16 causes the sprocket 15 and the drive shaft 1 to rotate relative to each other so that the lift center angle is retarded. That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The phase variable mechanism 12 can have various configurations such as those using a hydraulic or electromagnetic actuator.

  The lift / operating angle variable mechanism 13 and the phase variable mechanism 12 are controlled by a control unit (not shown) as control means in accordance with the operating state such as the vehicle speed and the engine speed.

  Next, the swing cam 6 and the rocker arm 17 will be described with reference to FIG.

  The profile of the cam lobe sliding surface 6b of the swing cam 6 is a part of the cam lobe sliding surface 6b as shown in FIG. 2, specifically, at the beginning of the valve opening operation of the intake valve 20 (hereinafter referred to as a valve event). A portion in contact with a cam follower 18 described later has a shape recessed toward the inner peripheral side of the swing cam 6. Hereinafter, the recessed portion is referred to as a “concave portion”, the curvature radius of the recess portion is negative, and the curvature radius of other portions is positive.

  The rocker arm 17 has a pivot 21 on the opposite side of the rocking shaft 6a of the rocking cam 6 from the cam lobe sliding surface 6b, and a substantially hemispherical valve follower 19 in contact with the upper end of the intake valve 20 on the lower surface. . The swing shaft 6 a is located between the pivot 21 and the intake valve 20. This is to obtain an effect of increasing the lift amount by providing a so-called rocker ratio.

  The cam follower 18 provided on the upper surface is a so-called slip type in which the contact portion with the cam lobe sliding surface 6b moves as the swing angle of the swing cam 6 changes. The curvature here is the reciprocal of the radius of curvature. That is, “large curvature” means that the radius of curvature is small.

  Next, a support structure between the drive shaft 1 and the swing cam 6 and a support structure of the drive shaft 1 to the engine will be described with reference to FIGS.

  3 (a) and 3 (b) are diagrams schematically showing a cross section of the swing cam 6 viewed from the engine front side, and FIGS. 3 (a) and 3 (b) are both cam lobe sliding surfaces. 6b is a view showing the inside of the valve lift where the cam follower 18 comes into contact. FIG. 3A shows the most advanced angle state when the phase variable mechanism 12 is used, and FIG. 3B similarly shows the most retarded angle state. Represents the case. In addition, the drive shaft 1 shall rotate clockwise in the figure.

  Also, the profile of the cam lobe sliding surface 6b is shown so that it becomes clear that the radius of curvature changes from positive to negative and then positive again from the start of lift, and the actual profile of the cam lobe sliding surface 6b is It is not limited to the same thing.

  The drive shaft 1 is a hollow circular tube through which lubricating oil flows. As a method of supplying the lubricating oil to the inside of the drive shaft 1, a method of supplying the lubricant from the end portion of the drive shaft 1 with an open end, or an oil hole as an oil supply mechanism in a portion supported by a bearing described later. There is a method of providing and supplying from a supply path provided in the bearing.

  The swing cam 6 is provided with a cam oil hole 22 that communicates the outer peripheral side of the cam lobe sliding surface 6b with the inner peripheral side of the swing coaxial, and the drive shaft 1 has an inner peripheral side and an outer peripheral side of the drive shaft 1. A drive shaft oil hole 23 that communicates is provided, and the sleeve-like member 25 has a sleeve oil hole 24 that communicates the inner peripheral side and the outer peripheral side of the sleeve-like member 25 with respect to the rotary shaft of the drive shaft 1. It is provided so that it may open to the lower side of the side where this is disposed.

  The sleeve oil hole 24 is longer in the circumferential direction than the drive shaft oil hole 23 and the cam oil hole 22.

  Therefore, only when the positions of the drive shaft oil hole 23, the sleeve oil hole 24, and the cam oil hole 22 coincide with each other and the three oil holes 22, 23, 24 communicate with each other, the lubricating oil in the drive shaft 1 slides on the cam lobe. It is supplied to the surface 6b.

  Instead of making the sleeve oil holes 24 longer in the circumferential direction, a plurality of sleeve oil holes 24 may be provided in the circumferential direction.

  FIG. 4 is a cross-sectional view of the swing cam 6 and the drive shaft 1 as viewed from the cylinder row direction.

  In FIG. 4, 25 is a sleeve-like member, 26 is a collar member, 27 is a lower drive shaft bearing, and 28 is a lower control shaft bearing. The sleeve-like member 25 is fixedly supported by a lower drive shaft bearing 27 and a lower control shaft bearing 28 via a collar member 26. The drive shaft 1 is freely rotatable with respect to the sleeve-like member 25.

  The lower control shaft bearing 28 also serves as the upper bearing of the drive shaft 1. For example, as shown in FIG. 5, the drive shaft 1 is supported by the upper surface of the lower drive shaft bearing 27 and the lower surface of the lower control shaft bearing 28, and the upper surface of the lower control shaft bearing 28 and the lower surface of the upper control shaft bearing 29. And the control shaft 7 is supported.

  By adopting such a bearing structure, the rigidity of the bearing portion can be increased as compared to providing separate bearings for the bearing for the control shaft 7 and the drive shaft 1. That is, when provided separately, the bearing for the control shaft 7 needs to be arched so as to straddle the drive shaft 1 in order to avoid interference with the drive shaft 1. However, when the bearing is shared as in the present embodiment, since the upper drive bearing 28 is provided under the control shaft 7, the rigidity is increased.

  The collar member 26 may be interposed between the swing cam 6 and the drive shaft 1 together with the sleeve-like member 25. In this case, the collar member 26 needs to be provided with an oil hole at the same position as the sleeve-like member 25.

  The minimum oil film thickness, the PV value, and the valve lift amount during the valve event of the valve mechanism using the swing cam 6 as described above will be described with reference to FIG. FIG. 6 is a diagram showing an example of the relationship between the above-described values at a predetermined lift amount and operating angle and the rotation angle of the drive shaft 1. For comparison, each value of a valve operating mechanism using a conventional rotating cam is also shown. In the figure, a solid line A indicates a case where the swing cam 6 is used, and a broken line B indicates a case where the rotating cam is used.

  Assuming that the drive shaft angle when the ramp section of the swing cam 6 before opening the valve (referred to as an up-ramp section) ends and immediately before the valve lift starts is θ1, the minimum oil film thickness is maximum immediately after the drive shaft angle θ1. Value.

  On the other hand, when the rotary cam is used, the maximum value is obtained at the initial stage of the valve lift, but the maximum value is smaller and the drive shaft angle at which the maximum value is reached is slower than when the swing cam 6 is used.

  This minimum oil film thickness is a value determined by the surface pressure and the oil film entrainment speed. Since the valve lift is not started immediately after the drive shaft angle θ1, the surface pressure is low. That is, when the minimum oil film thickness reaches the maximum value, the oil film entrainment speed increases.

  Note that the variation in the minimum oil film thickness is substantially symmetric with respect to the drive shaft angle that is the maximum lift amount, and therefore takes a peak value immediately before the start of the ramp section during the valve closing operation. However, the peak value is smaller than the maximum value because the surface pressure is lower during the valve closing operation.

  Further, in the vicinity of the drive shaft angle θ1, the radius of curvature of the portion of the swing cam 6 that contacts the cam follower 18 switches from positive to negative.

  The PV value takes peak values (maximum values) at two locations of the drive shaft angles θ2 and θ3 during the valve opening operation. The drive shaft angle θ2 substantially matches the drive shaft angle at which the positive valve acceleration ends, and the drive shaft angle θ3 switches the radius of curvature of the portion of the rocking cam 6 that contacts the cam follower 18 from negative to positive. It almost coincides with the drive shaft angle near the portion.

  Although the surface pressure P is low, the PV value at the drive shaft angle θ2 is large because the sliding speed V is large. On the other hand, the PV value at the drive shaft angle θ3 is large because the surface pressure P is large although the sliding speed V is small. Similar to the change in the minimum oil film thickness, the change in the PV value is substantially symmetrical with respect to the drive shaft angle that is the maximum lift amount, and therefore takes two peak values even during the valve closing operation. On the other hand, when the rotating cam is used, the peak of the PV value is only once from the start of the valve opening operation until the valve is closed.

  In FIG. 6, the first peak value of the PV value is larger than the second peak value, but the present invention is not limited to this, and the second peak value may be larger.

  Next, the positional relationship among the cam oil hole 22, the drive shaft oil hole 23, and the sleeve oil hole 24 will be described.

  The sleeve oil hole 24 is arranged so that the outer peripheral side open end coincides with the cam oil hole 22 and the inner peripheral side open end coincides with the outer peripheral side open end of the drive shaft oil hole 23 at the drive angle θ1.

  The open end of the cam oil hole 22 on the cam lobe sliding surface side opens near the position where the radius of curvature of the cam lobe sliding surface 6b switches from positive to negative, that is, near the position where the up-ramp section ends.

  With such a configuration, when the drive shaft angle becomes θ1, the cam oil hole 22 and the drive shaft oil hole 23 communicate with each other, and from the inside of the drive shaft 1 through the drive shaft oil hole 23 and the cam oil hole 22. Lubricating oil is supplied to the contact portion between the cam lobe sliding surface 6 b and the cam follower 18.

  The drive shaft angle θ1, that is, the vicinity of the end of the up-ramp section, is a position where the minimum oil film thickness is maximum, and is also a position where the PV value starts to rise sharply. Thus, the lubricity between the swing cam 6 and the cam follower 18 can be ensured.

  Further, the vicinity of the position where the radius of curvature of the cam lobe sliding surface 6b is switched from positive to negative is the position where the cam follower 18 comes into contact when the PV value starts to rise. The lubricity between the swing cam 6 and the cam follower 18 when the value is reached can be ensured. Furthermore, since the surface pressure when contacting the cam follower 18 is low at the position where the radius of curvature switches from positive to negative, the durability of the swing cam 6 can be improved even if the oil hole 22 penetrating the swing cam 6 is provided. There is no loss.

  By the way, the variable valve mechanism of the present embodiment can change the lift amount, the operating angle, and the phase by operating the lift / operating angle variable mechanism 13 or the phase variable mechanism 12.

  For example, when the lift amount is reduced by the lift / operating angle variable mechanism 13, as shown in FIG. 9A, the central angle does not change and the operating angle becomes small, so the valve lift start timing is delayed. Further, according to the phase variable mechanism 12, the valve lift start timing can be advanced or retarded independently of the operating angle.

  For this reason, the value corresponding to the drive shaft angles θ1 to θ3 described above and the drive shaft angle at which the cam oil hole 22 and the drive shaft oil hole 23 coincide with each other change. FIG. 9A is a diagram showing a change in operating angle and lift amount by the lift / operating angle variable mechanism 13, and FIG. 9B is an enlarged view of a valve lift starting portion in FIG. 9A. .

  Incidentally, as described above, the circumferential length of the sleeve oil hole 24 is longer than that of the cam oil hole 22 and the drive shaft oil hole 23. For example, as shown in FIGS. If the circumferential length of 24 is set to be long enough for the three oil holes to communicate in the vicinity of the end of the up-ramp section in any of the most advanced angle, the most retarded angle, the maximum operating angle, and the minimum operating angle, Alternatively, at least in the most advanced angle state, the most retarded angle state, the maximum operating angle state, and the minimum operating angle state, the cam oil hole 22, the drive shaft oil hole 23, and the sleeve oil hole 24 are communicated with each other. If a plurality of sleeve oil holes 24 are provided in the direction, even if the drive shaft angle at which the cam oil hole 22 and the drive shaft oil hole 23 coincide as shown in FIG. Lubricating oil can be supplied near the end of the section.

  When the variable control by the lift / working angle variable mechanism 13 and the phase variable mechanism 12 is not performed, the circumferential length of the sleeve oil hole 24 may be equal to that of the drive shaft oil hole 23 and the cam oil hole 22. .

  Further, the sleeve-like member 25 may not be interposed between the swing cam 6 and the drive shaft 1. In this case, in order to cope with a change in the center angle by the lift / operation angle variable mechanism 13 or the phase variable mechanism 12, the drive shaft oil holes 23 may be elongated in the circumferential direction, or a plurality of them may be provided in the circumferential direction. Good.

  Further, in the present embodiment, the rocker arm 17 is interposed between the swing cam 6 and the intake valve 20, but even a so-called direct acting type is applicable if the tappet (valve lifter) is curved. .

  As described above, according to the present embodiment, the following effects can be obtained.

  The rocking arm 6 includes a rocking cam 6 and a rocker arm having a curved tappet. The sliding surface 6b of the cam lobe of the rocking cam 6 has a radius of curvature that changes from positive to negative as the distance from the base circle increases. Since the lubricating oil is supplied between the swing cam 6 and the cam follower 18 before the PV value between the swing cam 6 and the cam follower 18 reaches the maximum, the most necessary lubrication is required. The lubricating oil can be reliably supplied before reaching the maximum PV value. In addition to supplying the lubricating oil at a predetermined timing as in this embodiment, the lubricating oil may be continuously supplied during a period before the maximum PV value is reached.

  Since the lubricating oil is supplied in a predetermined section during the period from when the intake valve 20 starts to lift until the PV value becomes maximum, an oil film is easily formed between the swing cam 6 and the cam follower 18 by the start of the lift. Lubricating oil can be supplied in this state.

  By setting the predetermined section in the vicinity of the timing when the up-ramp section of the intake valve 20 ends, that is, in the vicinity of the position where the minimum oil film thickness becomes maximum and the PV value starts to rise sharply, the PV value Before reaching the peak, the lubricating oil can be supplied to the position where the minimum oil film thickness is maximized, thereby ensuring lubricity.

  An oil passage provided in the drive shaft 1 and a cam oil hole 22 are provided, and lubricating oil is supplied from the cam oil hole 22 between the swing cam 6 and the cam follower 18, so that the direction of motion is reversed after the peak lift. Even in the downward lift section in which the cam lobe jumps upward, the lubrication between the swing cam and the cam follower 18 can be ensured without hindering the entrainment of lubricating oil as in the case of dripping from above the swing cam. it can.

  Since the cam lobe side open end of the cam oil hole 22 opens near the position where the curvature radius of the cam lobe changes from positive to negative, it is the time when the PV value starts to rise and the minimum oil film thickness becomes the maximum value. Lubricating oil can be supplied and lubricity can be ensured.

  The swing cam 6 is a separate member from the drive shaft 1 and is swingably attached to the drive shaft 1. The drive shaft 1 is provided with a shaft oil hole 23, and the cam oil hole 22 and the drive shaft oil are provided. Since the lubricating oil is supplied by communicating with the hole 23, it is possible to prevent a decrease in hydraulic pressure due to the constant supply of the lubricating oil.

  A sleeve-like member 25 having a sleeve oil hole 24 is interposed between the swing cam 6 and the drive shaft 1, and the sleeve oil hole 24, the drive shaft oil hole 23, and the cam oil hole 22 communicate with each other so that the lubricating oil is obtained. Therefore, even if the cam oil hole 22 and the drive shaft oil hole 1 coincide with each other at a position different from the position of the sleeve oil hole 24, the lubricating oil is not supplied, so that the lubricating oil is supplied only at a desired timing. Can be supplied.

  Even if the opening / closing timing of the intake valve 20 is either the most advanced angle or the most retarded angle, the sleeve oil hole 24 is circumferentially arranged so that the cam oil hole 22, the drive shaft oil hole 23, and the sleeve oil hole 24 communicate with each other. Since it is long in the direction or formed in plural, the lubricating oil can be supplied at a desired timing even when the center angle of the lift of the intake valve 20 is changed by the phase variable mechanism 12.

  The sleeve-like member 25 is fixed by a collar member 26, and the lower control shaft bearing 28 of the control shaft 7 is shared for fixing the collar member 26. Therefore, the rigidity of the bearing portion is increased, and thereby the load acting during engine operation is increased. Can prevent the control shaft 7 from falling down.

  Unlike the valve lifter, the rocker arm 17 cannot form a hole for storing the lubricating oil, but since the lubricating oil is supplied from the sliding surface 6b of the cam lobe, the lubricity can be ensured.

  A second embodiment will be described with reference to FIG. FIG. 7 is a diagram corresponding to FIG. 3A of the first embodiment.

  The basic configuration of this embodiment is the same as that of the first embodiment, but the position of the open end of the cam oil hole 22 on the cam lobe sliding surface side, the drive shaft oil hole 23, the sleeve oil hole 24, and the cam oil. The drive shaft angle with which the hole 22 communicates is different.

  As shown in FIG. 7, the open end on the cam lobe sliding surface side opens to a position where the radius of curvature of the cam lobe sliding surface 6b is switched from negative to positive, and the three oil holes 22, 23, 24 communicate with each other. This is done when the drive shaft angle is θ3 in FIG.

  When the portion where the radius of curvature switches from negative to positive comes into contact with the cam follower 18, the PV value becomes the second peak, and therefore, by supplying lubricating oil here, between the swing cam 6 and the cam follower 18. The lubricity can be ensured.

  Further, the acceleration characteristics of the intake valve 20 are examined based on the profile of the cam lobe sliding surface 6b, and when the positive acceleration section (the acceleration in the valve opening direction is positive) ends (drive shaft angle θ2 in FIG. 6). Alternatively, the cam lobe sliding surface side open end may be provided on the cam lobe sliding surface 6b in the vicinity of the position in contact with the cam follower 18. According to this, lubricating oil can be supplied at the first peak of the PV value.

  As described above, in this embodiment, as in the first embodiment, even in the valve operating mechanism using the swing cam 6, the lubricating oil can be reliably supplied between the swing cam 6 and the cam follower 18. Can be secured.

  A third embodiment will be described with reference to FIG. FIG. 8 is a diagram schematically showing a cross section of the swing cam 6 viewed from the engine front side. For simplicity, FIG. 8 shows a case where there is no change in the lift amount, the operating angle, and the central angle by the lift / operating angle variable mechanism 13 and the phase variable mechanism 12.

  In the present embodiment, as shown in FIG. 8, two cam oil holes 22, two drive shaft oil holes 23, and two sleeve oil holes 24 (cam oil holes 22a, 22b, drive shaft oil holes 23a, 23b, sleeve oil It is different from the first embodiment in that the holes 24a and 24b are provided.

  The cam oil sliding surface side open end of the cam oil hole 22a is provided in the vicinity of a portion where the radius of curvature of the cam lobe sliding surface 6b changes from positive to negative, and the cam oil sliding surface side open end of the cam oil hole 22b is cam lobe. It is provided in the vicinity of a portion where the radius of curvature of the sliding surface 6b changes from negative to positive.

  The sleeve oil hole 24a is arranged so that the portion where the radius of curvature of the cam lobe sliding surface 6b is switched from positive to negative communicates with the cam oil hole 22a when contacting the cam follower 18, and the drive shaft oil hole 23a is sleeve oil. The hole 24a and the cam oil hole 22a are arranged so as to communicate with the sleeve oil hole 24a when they communicate with each other.

  On the other hand, the sleeve oil hole 24b is arranged so that the portion where the radius of curvature of the cam lobe sliding surface 6b switches from negative to positive communicates with the cam oil hole 22b when contacting the cam follower 18, and the drive shaft oil hole 23b is The sleeve oil hole 24b and the cam oil hole 22b are arranged so as to communicate with the sleeve oil hole 24b when they communicate with each other.

  With the above configuration, the lubricating oil can be supplied between the swing cam 6 and the cam follower 18 at both the drive shaft angles θ1 and θ3 in FIG. Further, when one is in communication, the other is not in communication, so that lubricating oil is not supplied from two locations at the same time. Thereby, the fall of oil pressure can be prevented.

  For example, the cam oil hole 22a, the drive shaft oil hole 23a, and the sleeve oil hole 24a are made larger in diameter than the cam oil hole 22b, the drive shaft oil hole 23b, and the sleeve oil hole 24b. The amount of lubricating oil supplied from 22a is set to be larger than the amount of lubricating oil supplied from the cam oil hole 22b. As a result, more lubricating oil is supplied at the driving shaft angle at which the PV value becomes larger among the two peaks of the PV value, so that the amount of lubricating oil supplied according to the PV value is obtained and the lubricity is ensured. And the lubricating oil can be used efficiently.

  Further, one of the two oil holes 22 in FIG. 8 may be provided with a cam oil hole 22 that opens in a portion that contacts the cam follower 18 when the positive acceleration of the intake valve 20 is finished. 22 may be provided as a third oil hole 22 in addition to the two oil holes 22 in FIG.

  When the lift amount, the operating angle, and the center angle are changed by the lift / operating angle variable mechanism 13 and the phase variable mechanism 12, the sleeve oil holes 24a and 24b may be elongated in the circumferential direction as in the first embodiment. In this case, the oil holes 22a to 24a communicating at the drive shaft angle θ1 and the oil holes 22b to 24b communicating at the drive shaft angle θ3 are shifted in the axial direction of the drive shaft 1. Thereby, the fall of the oil_pressure | hydraulic by supplying lubricating oil from two places simultaneously can be prevented.

  As described above, in the present embodiment, in addition to the same effects as those of the first embodiment, the swing cam 6 and the cam follower are further applied during a predetermined period before the PV value between the swing cam 6 and the cam follower 18 becomes maximum. Since there is an opportunity to supply the lubricating oil twice with 18, the lubricity at the peak of the PV value that is twice during the valve lift is secured while preventing the hydraulic pressure from being lowered by always supplying it. be able to.

  In addition, it is also possible to make the opportunity of lubricating oil supply 3 times or more by providing three or more each oil holes 22-24.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

It is a figure showing the variable valve mechanism of 1st Embodiment. It is the figure which looked at the variable valve mechanism from the engine front side. (A), (b) is sectional drawing seen from the engine front side of the rocking cam (1st Embodiment). It is sectional drawing seen from the engine side in the vicinity of a rocking cam. It is a figure showing the bearing part of a sleeve-shaped member and a collar member. It is a figure showing the relationship between a drive shaft angle, minimum oil film thickness, PV value, and valve lift amount. It is sectional drawing seen from the engine front side of the rocking cam (2nd Embodiment). (A), (b) is sectional drawing seen from the engine front side of the rocking cam (3rd Embodiment). (A), (b) is a figure showing the change of the operating angle and valve lift amount by a lift and an operating angle variable mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control shaft 2 Eccentric cam 3 Link arm 4 Variable valve rocker arm 5 Link member 6 Oscillating cam 7 Control shaft 8 Eccentric cam part 12 Phase variable mechanism 13 Lift / operating angle variable mechanism 14 Hydraulic actuator for lift / operating angle control DESCRIPTION OF SYMBOLS 15 Sprocket 16 Phase control actuator 17 Valve drive rocker arm 18 Cam follower 19 Valve follower 20 Intake valve 21 Pivot 22 Cam oil hole 23 Drive shaft oil hole 24 Sleeve oil hole 25 Sleeve-like member 26 Color member

Claims (20)

A swing cam;
A curved tappet interposed between the swing cam and the valve;
An oil supply mechanism for supplying lubricating oil to the swing cam and the curved surface tappet;
With
In the variable valve mechanism in which the radius of curvature changes from positive to negative and from negative to positive again as the sliding surface of the swing cam with the tappet moves away from the base circle,
The internal combustion engine, wherein the oil supply mechanism supplies lubricating oil between the swing cam and the curved tappet before the PV value between the swing cam and the curved tappet is maximized. Valve mechanism.   2. The valve for an internal combustion engine according to claim 1, wherein the oil supply mechanism supplies lubricating oil in a predetermined section during a period from when the valve starts to lift until the PV value becomes maximum. mechanism.   The valve operating mechanism for an internal combustion engine according to claim 2, wherein the predetermined section is in the vicinity of the end timing of the up-ramp section.   4. The valve operating mechanism for an internal combustion engine according to claim 2, wherein the predetermined section is in the vicinity of a time when the acceleration of the valve changes from positive to negative.   The valve operating mechanism for an internal combustion engine according to any one of claims 2 to 4, wherein the predetermined section is in the vicinity of a time when the PV value becomes maximum.   When the maximum value of the PV value is the second maximum value from the start of the lift, the oil supply mechanism is configured so that the swing cam and the curved surface tappet are in the vicinity of the time when the first maximum value is obtained from the lift start. 6. A valve operating mechanism for an internal combustion engine according to claim 5, wherein lubricating oil is supplied between them.   When the maximum value of the PV value is the first maximum value from the start of the lift, the oil supply mechanism is configured such that the swing cam, the curved surface tappet, 6. A valve operating mechanism for an internal combustion engine according to claim 5, wherein lubricating oil is supplied between the two. The oil supply mechanism is
An oil passage provided in the swing shaft of the swing cam;
A cam oil hole penetrating the cam lobe of the rocking cam and communicating the outside of the rocking cam and the inside of the rocking shaft;
With
The valve operating mechanism for an internal combustion engine according to any one of claims 1 to 7, wherein lubricating oil is supplied between the swing cam and the curved tappet from the cam oil hole.   9. The valve operating mechanism for an internal combustion engine according to claim 8, wherein the cam lobe side open end of the cam oil hole opens near a position where the radius of curvature of the cam lobe changes from positive to negative.   9. The valve operating mechanism for an internal combustion engine according to claim 8, wherein the cam lobe side open end of the cam oil hole opens near a position where the radius of curvature of the cam lobe changes from negative to positive. The swing cam is a separate member from the swing shaft, and is swingably attached to the swing shaft.
The rocking shaft is provided with a shaft oil hole that communicates the inside and the outside of the rocking shaft.
The valve operating mechanism for an internal combustion engine according to any one of claims 1 to 10, wherein lubricating oil is supplied by the cam oil hole and the shaft oil hole communicating with each other. A phase variable mechanism that advances and retards the opening and closing timing of the valve by changing the phase of the swing cam and the swing shaft;
Regardless of whether the valve is opened or closed at the most advanced angle or the most retarded angle, the shaft oil hole is arranged in the circumferential direction so that the cam oil hole communicates with the shaft oil hole during the predetermined period. 12. The valve operating mechanism for an internal combustion engine according to claim 11, wherein the valve operating mechanism is long. A phase variable mechanism that advances and retards the opening and closing timing of the valve by changing the phase of the swing cam and the swing shaft;
Regardless of whether the valve is opened or closed at the most advanced angle or the most retarded angle, the shaft oil hole is arranged in the circumferential direction so that the cam oil hole communicates with the shaft oil hole during the predetermined period. 12. The valve operating mechanism for an internal combustion engine according to claim 11, wherein a plurality of valve operating mechanisms are provided. A lift amount / operating angle variable mechanism capable of continuously enlarging / reducing the lift amount and operating angle of the valve,
The shaft oil hole is elongated in the circumferential direction so that the cam oil hole and the shaft oil hole communicate with each other during the predetermined period regardless of whether the lift amount and operating angle of the valve are maximum or minimum. The valve operating mechanism for an internal combustion engine according to any one of claims 11 to 13, wherein the valve operating mechanism is formed. A lift amount / operating angle variable mechanism capable of continuously enlarging / reducing the lift amount and operating angle of the valve,
A plurality of shaft oil holes are provided in the circumferential direction so that the cam oil hole and the shaft oil hole communicate with each other during the predetermined period regardless of whether the lift amount and operating angle of the valve are maximum or minimum. The valve operating mechanism for an internal combustion engine according to any one of claims 11 to 13, wherein the valve operating mechanism is provided. A longitudinal notch or an oil hole is provided between the swing cam and the swing shaft, and a sleeve-like member that does not rotate with respect to the swing shaft and the swing cam is interposed.
The internal combustion engine according to any one of claims 11 to 15, wherein lubricating oil is supplied by the cutout or oil hole in the longitudinal direction communicating with the shaft oil hole and the cam oil hole. Valve mechanism of the engine.   The cam oil hole, the shaft oil hole, and the longitudinal notch or oil hole communicate with each other during the predetermined period regardless of whether the valve is opened or closed at the most advanced angle or the most retarded angle. The valve operating mechanism for an internal combustion engine according to claim 16, wherein the longitudinal notch or oil hole is formed long in the circumferential direction.   The cam oil hole, the shaft oil hole, and the longitudinal notch or oil hole communicate with each other during the predetermined period regardless of whether the valve is opened or closed at the most advanced angle or the most retarded angle. The valve operating mechanism for an internal combustion engine according to claim 16, wherein a plurality of the longitudinal notches or oil holes are provided in the circumferential direction. The pivot shaft rotating in conjunction with the engine;
A control shaft extending substantially parallel to the swing shaft;
A drive cam that is eccentrically fitted on the outer periphery of the swing shaft and is rotatably fitted;
A ring-shaped link rotatably fitted on the drive cam;
A swing arm having one end connected to the ring-shaped link and swinging around the control shaft in conjunction with rotation of the swing shaft;
A rod-shaped link having one end connected to the other end of the swing arm;
The swing cam connected to the other end of the rod-shaped link to open and close the valve;
With
The sleeve-like member is fixed by a collar member interposed between the swing cam and the swing shaft,
19. The valve operating mechanism for an internal combustion engine according to claim 11, wherein a bearing of the control shaft is shared for fixing the collar member.   20. The valve operating mechanism for an internal combustion engine according to claim 1, wherein the curved tappet is a cam follower portion of a rocker arm interposed between the valve and the swing cam. .