JP4589286B2 - Variable valve opening characteristics internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve opening characteristic internal combustion engine, and more particularly, to a technique for realizing a reduction in the number of components and an improvement in lubricity.

  Many 4-cycle gasoline engines (hereinafter simply referred to as engines) are equipped with various valve opening characteristic variable mechanisms in order to improve output and fuel consumption, reduce harmful exhaust gas components, and the like. As a valve opening characteristic variable mechanism, there is a mechanism that switches between a low-speed cam and a high-speed cam according to the operating situation. However, in recent years, in order to realize further improvement of transient characteristics and reduction of throttle, etc. One that variably controls the phase and valve lift individually has become the mainstream. As a variable valve lift device used for variable valve lift control, a control arm or control link for variable valve lift is installed between the cam and rocker arm to change the fulcrum of the control arm or the geometry of the control link. There has been proposed one in which the valve lift is changed by making it (see Patent Documents 1 and 2).

As a variable valve lift device for a multi-cylinder engine, the inventors of the present invention supported a control shaft for operating a variable valve lift mechanism for each cylinder on a cam holder, and installed this control shaft at the end of a cylinder head. We have developed an electric actuator that is driven to rotate. In this variable valve lift device, the control shaft is supported by each cam holder via a plurality of shaft levers, and the drive side shaft lever and the control shaft are fastened by bolts, while being interposed between the cam shaft and the rocker arm. The roller link that holds the rotating roller is rotatably held on the control shaft.
JP 2004-521234 A JP 2005-248874 A

  However, when such a configuration is adopted, the shaft shaft on the drive side and the control shaft are fastened, so the control shaft and the roller link are always in pressure contact with each other, and local wear or the like occurs on the contact surface. There was a problem that made it easier to do. In addition, bolts for fastening the shaft lever on the drive side and the control shaft, processing of screw holes and seating surfaces, and non-rotating members (lock washers, etc.) are required, increasing the number of parts and processing / assembly man-hours. It was inevitable. Further, since the shaft lever at the end is cantilevered on the side surface of the cam holder, the support rigidity is lowered and the control shaft is bent, which may cause uneven valve lift among the cylinders. It was. In addition, since the roller held by the roller link always slides with the camshaft and the rocker arm, it is necessary to effectively lubricate these sliding surfaces. However, because of the structure, engine oil is supplied around the roller. It was difficult. In addition, the shaft lever needs to be increased in strength and rigidity so that it can withstand input from the electric actuator and roller link. However, if the vertical width is increased, it will approach the camshaft when it swings upward. There was a fear.

  The present invention has been made in view of the above situation, and an object thereof is to provide a variable valve opening characteristic internal combustion engine that realizes reduction in the number of components and improvement in lubricity.

The invention according to claim 1 is a camshaft that is used to drive opening and closing of a valve, a valve arm that is interposed between the camshaft and the valve, and transmits a rotational force of the camshaft to the valve; A control shaft that is pivotably supported via a plurality of shaft levers with respect to the internal combustion engine body side, and is swingably supported by the control shaft in a manner sandwiched between the shaft levers, and the rotation by the valve arm A variable valve opening characteristic internal combustion engine having a control link for changing a transmission amount of force, wherein each of the plurality of shaft levers is formed with a holding sleeve for floatingly supporting the control shaft, and the plurality of shafts Of the levers, a holding slot for the end side shaft lever that supports the end side of the control shaft. Bed has exhibited a bottomed cylindrical shape, the open end of the retaining sleeve of the end-side shaft lever, characterized in that in proximity to the control link from the end portion of the retaining sleeve of another shaft lever.

According to a second aspect of the present invention, there is provided a camshaft that is used for opening and closing a valve, and a valve operating arm that is interposed between the camshaft and the valve and transmits a rotational force of the camshaft to the valve. And a control shaft that is pivotably supported via a plurality of shaft levers with respect to the internal combustion engine body side, and is swingably supported by the control shaft so as to be sandwiched between the shaft levers. A variable valve opening characteristic internal combustion engine having a control link for changing the amount of transmission of the rotational force, wherein the plurality of shaft levers are respectively formed with holding sleeves for floatingly supporting the control shaft, and the control The link has a pair of arms spaced apart in the axial direction, and the pair of arms are connected to the control shaft. And having a rib for connecting the bottom of the up side.

According to a third aspect of the present invention, there is provided a camshaft that is used for opening and closing a valve, and a valve operating arm that is interposed between the camshaft and the valve and transmits a rotational force of the camshaft to the valve. And a control shaft that is pivotably supported via a plurality of shaft levers with respect to the internal combustion engine body side, and is swingably supported by the control shaft so as to be sandwiched between the shaft levers. A variable valve opening characteristic internal combustion engine comprising a control link for changing the amount of transmission of the rotational force, wherein the plurality of shaft levers are each formed with a holding sleeve for floatingly supporting the control shaft, At least one of the shaft levers has a lower edge extending downward .

According to the first aspect of the present invention, since the control shaft freely rotates, the press contact portion between the control shaft and the roller link changes according to the operating state of the engine, and local wear on the contact surface is suppressed. In addition, the control shaft is held so as not to move in the axial direction by the bottomed cylindrical holding sleeve of the end side shaft lever, so a bolt or screw hole for fastening the driving side shaft lever and the control shaft In addition, the processing of the seating surface and the non-rotating member are not necessary, and the manufacturing cost and the number of assembly steps can be reduced. Further, the control shaft holding length by the end side shaft lever is increased, the control shaft is less likely to be bent due to a decrease in holding rigidity, and unevenness of valve lift between cylinders is suppressed. According to the second aspect of the present invention, the engine oil scattered in the cam chamber is collected in the recess defined by the rib and the arm, and then supplied to the roller or the like by the swinging of the roller link. The sliding surface between the roller and the camshaft or the rocker arm is effectively lubricated. According to the invention of claim 3 , the strength and rigidity of the shaft lever can be improved while preventing interference with the camshaft.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a main part of an upper part of an engine according to the embodiment, FIG. 2 is a perspective view showing a main part of the VLC mechanism according to the embodiment, and FIG. 3 is a main part fracture III in FIG. 4 is a perspective view showing a connection state between the drive lever and the control shaft, FIG. 5 is a perspective view showing a connection state between the front shaft lever and the control shaft, and FIG. 6 is a middle shaft. FIG. 7 is a perspective view showing a connection state between the lever and the control shaft, FIG. 7 is a longitudinal sectional view showing a connection portion between the middle shaft lever and the middle cam holder, and FIG. 8 is a perspective view showing a roller link. In the embodiment, for the convenience of explanation, the lower left in FIG.

<< Configuration of Embodiment >>
<Overall configuration>
An engine (variable valve opening characteristic type internal combustion engine) E shown in FIG. 1 is a four-cycle in-line four-cylinder gasoline engine for automobiles, and the cylinder head 1 includes two cylinders as shown in FIGS. A DOHC 4-valve type valve operating mechanism is provided for driving the exhaust valve 2 and the intake valve 3 respectively by the exhaust camshaft 4 and the intake camshaft 5. An exhaust rocker arm 6 is interposed between the exhaust valve 2 and the exhaust camshaft 4, and an intake rocker arm 7 is interposed between the intake valve 3 and the intake camshaft 5. The exhaust valve 2 and the intake valve 3 are always urged in the closing direction by the valve springs 9 and 10.

  Five cam holders (support members) 11 to 15 are fastened to the upper surface of the cylinder head 1, and the cam shafts 4 and 5 and the rocker arms 6 and 7 are rotatably supported by the cam holders 11 to 15. In the present embodiment, among the cam holders 11 to 15, the right end one is referred to as the front cam holder 11, the left end one as the rear cam holder 15, and the other three as middle cam holders 12 to 14, respectively. A flat plate-like upper plate 18 is fastened to the upper surfaces of the cam holders 11 to 15, and the valve mechanism is covered with the upper plate 18 and the head cover 19.

  The engine E of the present embodiment includes a variable valve timing control (VTC) mechanism 41 that variably controls the angle phase of the exhaust camshaft 4 and a VLC (variable control of the lift amount of the exhaust valve 2) as a valve opening characteristic variable mechanism. Variable valve Lift Control) mechanism 20 is mounted.

<VLC mechanism>
As shown in FIGS. 1 to 3, the VLC mechanism 20 includes an electric actuator 21 installed on the left side of the cylinder head 1, and a drive lever (end portion side) having a base end attached to a shaft 21 a of the electric actuator 21. (Shaft lever) 22, a hollow control shaft 23 held / driven by the drive lever 22, a front shaft lever (end-side shaft lever) 24 for swingingly supporting the control shaft 23 on the front cam holder 11, A middle shaft lever 25 that swingably supports the control shaft 23 on the middle cam holders 12 to 14, a roller link (control link) 26 in which the control shaft 23 is loosely fitted at its base end, and a roller at the tip of the roller link 26 A robot that is rotatably supported via a shaft 27. And La 28, and a spring unit 29 to constantly urge the roller 28 into the exhaust camshaft 4 side as the primary component.

  As shown in FIG. 4, a bottomed cylindrical holding sleeve 22a is formed on the swing end side of the drive lever 22, and the left end of the control shaft 23 is loosely fitted / locked to the holding sleeve 22a. . Further, as shown in FIG. 5, a bottomed cylindrical holding sleeve 24a is also formed on the swing end side of the front shaft lever 24, and the right end of the control shaft 23 is loosely fitted / engaged with the holding sleeve 24a. Has been. In the present embodiment, engine oil for lubrication is supplied from the drive lever 22 into the hollow portion of the control shaft 23, and this engine oil is used as the front shaft lever 24, the middle shaft lever 25, the roller link 26, and the control shaft 23. To the mating surface.

  As shown in FIG. 6, a cylindrical holding sleeve 25a is formed on the rocking end side of the middle shaft lever 25, and the control shaft 23 is loosely fitted to the holding sleeve 25a. The middle shaft lever 25 has a pair of left and right arms 25b and 25c that sandwich the middle cam holders 12 to 14, and the middle cam holders 12 to 12 are supported by support pins 31 that are fitted on the base ends of the arms 25b and 25c. 14.

  As shown in FIG. 6, the lower edges of the arms 25 b and 25 c are extended downward to ensure sufficient strength and rigidity while preventing interference with the camshaft 4. Further, as shown in FIG. 7, since the left and right end surfaces of the support pin 31 are locked by flanges 4a and 4b formed on the camshaft 4, it is necessary to use a retaining ring or the like for preventing the support pin from coming off. In addition, the support pins 31 do not protrude to the left and right of the arms 25b and 25c, and the space can be reduced. In the roller link 26 of this embodiment, in order to improve the strength of the roller link 26 while preventing interference with the middle cam holders 12 to 14, an inner corner portion is formed at the connecting portion between the holding sleeve 25a and the arms 25b and 25c. The curvature r1 is set to be small, and the curvature r2 at the outer corner is set to be large.

  As shown in FIG. 8, the roller link 26 includes a pair of left and right arms 26a and 26b, and a reinforcing rib 26c that connects the arms 26a and 26b at the lower part on the base end side (that is, the control shaft 23 side). Is formed. The roller link 26 has a recess 26d for collecting engine oil scattered in the cam chamber by the arms 26a, 26b and the rib 26c.

  The middle shaft lever 25 (that is, the control shaft 23) is swiveled steplessly between a position indicated by a solid line (minimum lift position) and a position indicated by a broken line (maximum lift position) in FIG. The roller link 26 swings around the minimum lift point P1 when the control shaft 23 is at the minimum lift position, and swings around the maximum lift point P2 when the control shaft 23 is at the maximum lift position. . On the end surfaces of the middle cam holders 12 to 14 (FIG. 9 shows the middle cam holder 13), an upper stopper portion 13a for restricting the counterclockwise rotation of the middle shaft lever 25 and the middle shaft lever 25 are provided. A lower stopper portion 13b that restricts clockwise rotation is formed. That is, in the present embodiment, the rotation range of the middle shaft lever 25 is regulated by forming the stopper portions 13a and 13b in the middle cam holder 13 instead of installing an independent stopper member. Since the middle shaft lever 25 rotates only between the minimum lift position and the maximum lift position, wear or the like due to contact with the holding sleeve 25a or the stopper portions 13a and 13b does not occur during normal operation. When the middle shaft lever 25 overruns from the minimum lift position or the maximum lift position for some reason, the holding sleeve 25a is locked to the upper stopper portion 13a or the lower stopper portion 13b.

  As shown in FIG. 9, the roller 28 is sandwiched between the arms 26 a and 26 b of the roller link 26, and the upper surface thereof is in rolling contact with the cam lobe 4 d of the exhaust camshaft 4. The roller shaft 27 is in rolling contact with a circular arc surface 6 a formed on the exhaust rocker arm 6. In addition, the circular arc surface 6a has a center P3 obliquely above and below the minimum lift point P1.

<< Operation of Embodiment >>
When the engine E of the automobile is started, an engine ECU (not shown) sets a target lift amount of the exhaust valve 2 based on various operation information such as a depression amount of a throttle pedal by a driver and a cooling water temperature, and the VLC mechanism 20 A drive current is output to the electric actuator 21. Then, the drive lever 22 attached to the shaft 21a of the electric actuator 21 rotates and the control shaft 23 is driven to turn in either the forward or reverse direction.

  When obtaining a combustion state that increases the amount of internal EGR that can be compressed and ignited, the engine ECU rotates the middle shaft lever 25 to the minimum lift position and rolls the roller link 25 around the minimum lift point P1, as shown in FIG. Oscillate. As a result, even when the roller 28 is pushed down by the cam lobe 4d, the roller shaft 27 rolls along the arc surface 6a as shown by an arrow in FIG. 2 lift amount) is minimized. In the normal combustion state, the engine ECU turns the control shaft 23 to the maximum lift position and the roller link 26 swings the roller link 25 around the maximum lift point P2, as shown in FIG. Like that. Thereby, when the roller 27 is pushed down by the cam lobe 4d, the roller shaft 26 hardly rolls along the arc surface 6a, so that the lift amount of the exhaust valve 2 is maximized.

  During operation of the engine E, the drive lever 22, the front shaft lever 24, the middle shaft lever 25, and the roller link 26 are constantly swung with respect to the control shaft 23. However, since the control shaft 23 is fitted to each of the levers 24 to 25 and the roller link 26 in a floating state, the control shaft 23 rotates relatively freely and engine oil is supplied to each fitting surface. In combination, there is no local wear or the like on the sliding surface with these. In the case of this embodiment, the control shaft 23 is locked in the axial direction by the holding sleeve 22a of the drive lever 22 and the holding sleeve 24a of the front shaft lever 24, so that locking means such as bolts are unnecessary. Thus, the number of parts and the number of processing / assembly processes can be reduced.

  In this embodiment, as shown in FIG. 12, the distance L1 from the opening end of the holding sleeve 22a of the drive lever 22 to the end of the roller link 26 and the opening end of the holding sleeve 24a of the front shaft lever 24 The distance L2 to the end of the roller link 26 is set much smaller than the distance L3 from the end of each middle shaft lever 25 to the end of the roller link 26. As a result, in this embodiment, the holding rigidity at both ends of the control shaft 23 is improved, the control shaft 23 is less likely to bend, and the unevenness of the valve lift among the cylinders is suppressed.

  On the other hand, in the present embodiment, as shown in FIG. 11, when the control shaft 23 turns to the maximum lift position, the base end of the roller link 26 comes to be positioned below, and the engine oil scattered in the cam chamber becomes the roller. It is collected in the recess 26 d of the link 26. Then, as shown in FIG. 10, when the control shaft 23 turns to the minimum lift position, the base end of the roller link 26 comes to be positioned upward, and the engine oil collected in the recess 26 d of the roller link 26. Is dropped / supplied to the roller 28 or the like. Thereby, lubrication between the roller 28 and the cam lobe 4d or the arc surface 6a is effectively performed without providing a complicated oil supply mechanism.

  On the other hand, in this embodiment, as shown in FIG. 13, since the roller link 26 moves slightly toward the control shaft 23, the initial setting of the tappet clearance can be made smaller than that of a normal engine, The seating noise and seating load can be reduced and the effective compression ratio can be improved without causing the exhaust valve 2 to be pushed up.

  Although the description of the specific embodiment is finished as described above, the present invention can be widely modified without being limited to the above-described embodiment and modifications. For example, the above embodiment and the modification are applied to an in-line four-cylinder DOHC gasoline engine that variably controls only the lift amount on the exhaust valve side, but the lift amount on the intake valve side is also variably controlled, Of course, it can be applied to V-type engines, SOHC engines, diesel engines, and the like. In addition, the shape of each shaft lever, roller link, and the like, and the specific configuration of the valve opening characteristic variable mechanism can be changed as appropriate without departing from the gist of the present invention.

It is a principal part perspective view which shows the upper part of the engine which concerns on embodiment. It is a perspective view which shows the principal part of the VLC mechanism which concerns on embodiment. It is a principal part fracture III arrow directional view in FIG. It is a perspective view which shows the connection state of a drive lever and a control shaft. It is a perspective view which shows the connection state of a front shaft lever and a control shaft. It is a perspective view which shows the connection state of a middle shaft lever and a control shaft. It is a longitudinal cross-sectional view which shows the connection part of a middle shaft lever and a middle cam holder. It is a perspective view which shows a roller link. It is a figure which shows the operating range of a VLC mechanism. It is operation | movement explanatory drawing of a VLC mechanism. It is operation | movement explanatory drawing of a VLC mechanism. It is a figure which shows the position of each shaft lever and roller link on a control shaft. It is a figure which shows the motion of the roller link at the time of a driving | operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder head 2 Exhaust valve 4 Exhaust cam shaft 6 Exhaust rocker arm 11 Front cam holder 12-14 Middle cam holder 15 Rear cam holder 20 VLC mechanism 21 Electric actuator 22 Drive lever (end side shaft lever)
22a Holding sleeve 23 Control shaft 24 Front shaft lever (end side shaft lever)
24a Holding sleeve 25 Middle shaft lever 25a Holding sleeve 26 Roller link (control link)
26a arm 26b arm 26c rib 28 roller E engine

Claims (3)

A camshaft for opening and closing the valve;
A valve arm that is interposed between the camshaft and the valve and transmits a rotational force of the camshaft to the valve;
A control shaft that is pivotally supported via a plurality of shaft levers with respect to the internal combustion engine body side;
A variable valve opening characteristic internal combustion engine comprising a control link that is swingably supported by the control shaft in a manner sandwiched between the shaft levers and that changes a transmission amount of the rotational force by the valve arm,
Each of the plurality of shaft levers is formed with a holding sleeve for floatingly supporting the control shaft ,
Of the plurality of shaft levers, the holding sleeve of the end side shaft lever that supports the end side of the control shaft has a bottomed cylindrical shape,
The valve opening characteristic variable type internal combustion engine, wherein the opening end of the holding sleeve of the end side shaft lever is closer to the control link than the end of the holding sleeve of the other shaft lever . A camshaft for opening and closing the valve;
A valve arm that is interposed between the camshaft and the valve and transmits a rotational force of the camshaft to the valve;
A control shaft that is pivotally supported via a plurality of shaft levers with respect to the internal combustion engine body side;
A control link that is swingably supported by the control shaft so as to be sandwiched between the shaft levers and changes the amount of transmission of the rotational force by the valve arm;
A variable valve opening characteristic internal combustion engine comprising:
Each of the plurality of shaft levers is formed with a holding sleeve for floatingly supporting the control shaft,
The variable valve opening characteristic internal combustion engine , wherein the control link has a pair of arms spaced apart in the axial direction and a rib connecting the pair of arms at a lower portion on the control shaft side . A camshaft for opening and closing the valve;
A valve arm that is interposed between the camshaft and the valve and transmits a rotational force of the camshaft to the valve;
A control shaft that is pivotally supported via a plurality of shaft levers with respect to the internal combustion engine body side;
A control link that is swingably supported by the control shaft so as to be sandwiched between the shaft levers and changes the amount of transmission of the rotational force by the valve arm;
A variable valve opening characteristic internal combustion engine comprising:
Each of the plurality of shaft levers is formed with a holding sleeve for floatingly supporting the control shaft,
At least one of the plurality of shaft levers has a variable valve opening characteristic internal combustion engine characterized in that a lower edge thereof extends downward .

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