JP2004132257A - Continuously variable valve device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuously variable valve device for an internal combustion engine controlling the valve lifting amount with high accuracy while increasing a speed of the rotation of an engine. <P>SOLUTION: This continuously variable valve device has holding levers 18 for each of cylinders in a state of being vertically extended to a position adjacent to an oscillation lever 15, an upper end part of the holding lever 18 is supported rotatably on an oscillation supporting point A of an oscillation lever 15, and its lower end part is rotatably supported at a position to regulate a valve close state of an intake valve 4. Each oscillation lever 15 is held by the holding lever 18 in each cylinder in a state that the oscillation supporting point A is slidable along between an eccentric cam 12a and a driving cam 13a on the position to regulate the valve close state of the intake valve 4. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a continuously variable valve apparatus for an internal combustion engine that can continuously vary a valve lift amount of a reciprocating valve by using movement of a swing fulcrum of a swing lever.
[0002]
[Prior art]
In a gasoline engine (internal combustion engine), a continuously variable valve train is mounted, and the work of the throttle bubble (adjustment of the amount of intake air) is performed by a reciprocating valve on the intake side provided in the cylinder head, that is, an intake valve. Attempts have been made to reduce pump loss caused by throttle bubbles.
[0003]
Conventionally, a structure using a swing lever having a swing fulcrum at an upper end and a contact surface at the lower end which abuts on an intake valve has been proposed for this continuously variable valve operating device.
[0004]
For this, a control shaft formed of an eccentric body capable of eccentricity is arranged on one upper side sandwiching the swing lever from the swing direction, and a camshaft is provided at an intermediate portion opposite to the control shaft sandwiching the swing lever. And an input part formed at the intermediate portion of the swing lever by a camshaft drive cam so that the swing fulcrum of the swing lever can be moved between the control shaft and the camshaft by using the eccentric displacement of the control shaft. A variable valve mechanism for inputting a driving force required for opening the valve is adopted. That is, when the swing fulcrum of the swing lever is swung by the eccentric displacement of the control shaft, the swing lever is tilted, and the area of the contact surface that contacts the intake valve moves. A base circular section and a lift section that determines the valve lift of the intake valve are formed in series on the contact surface of the swing lever along the space between the control shaft and the drive cam, and the intake valve is in contact with the base section. By moving the area of the base circle section and the lift section that are in contact with each other, the valve lift of the intake valve is continuously varied. The work of adjusting the intake air amount performed by the throttle valve is performed on behalf of the continuously variable valve lift amount (for example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-7-63023 (FIGS. 6 to 8)
[0006]
[Problems to be solved by the invention]
However, even when the eccentric cam is fixed at a certain position, the swing fulcrum moves during the movement period of the swing lever. Therefore, it is necessary to maintain the valve closed state by the movement of the swing lever and the shape of the roller contact surface.
[0007]
For this reason, there has been a problem that high machining accuracy is required for each part.
[0008]
For this reason, the swing fulcrum of the swing lever of each cylinder is connected by one common holding shaft, and the end of the holding shaft is swingably supported at the front and rear portions of the cylinder head so as not to be shaken. Conceivable. However, since the length of the holding shaft is long, the rigidity of the torsion or bending at the swing fulcrum of the swing lever is reduced, which may hinder high engine rotation.
[0009]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a continuously variable valve train for an internal combustion engine in which high-precision control of the valve lift is performed while increasing the engine speed.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is characterized in that a holding lever is disposed at an upper portion of a cylinder head so as to extend vertically in a position adjacent to a swing lever for each cylinder, and an upper end portion of the holding lever is provided. Is rotatably supported at the pivot point of the pivot lever, and the lower end is pivotally supported at a position defining the closed state of the reciprocating valve. The lever is pivotally held by each holding lever between the eccentric body and the drive cam around a position defining the state of the reciprocating valve when the swinging fulcrum is closed. .
[0011]
With this configuration, during the swing of the swing lever, the swing fulcrum of the swing lever is always fixed on the locus of an arc around the position that defines the valve closing state by the holding lever. For this reason, no matter what the valve lift amount is set, since the swing lever always adjusts the swing displacement based on the closing time, the variation in the opening / closing timing of the reciprocating valve is eliminated. . In addition, since the swing levers are held independently for each cylinder by holding levers arranged adjacent to each other, each of them operates with high support strength.
[0012]
Therefore, it is possible to control the valve lift amount with high accuracy while increasing the rotation speed of the engine.
[0013]
In addition to the above objects, the invention according to claim 2 has a simple structure, and one end of the reciprocating valve is supported by a support member so that the swing fulcrum of the swing lever is held with high rigidity and high accuracy. A rocker arm type that has a rocker arm that is swingably supported and that supports a rotatable roller in contact with an abutting surface at an intermediate portion, and a valve body that is opened and closed by swinging the other end of the rocker arm. The lower end of the holding lever is rotatably supported by the holding portion formed on the cylinder head at the axial center position of the roller when the valve is closed, and the upper end rotates at the swing fulcrum of the swing lever. The configuration uses a movably supported lever member.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on one embodiment shown in FIGS.
[0015]
1 in FIG. 1 shows a plane of a cylinder head of an internal combustion engine, for example, a reciprocating gasoline engine in which a plurality of cylinders are arranged in series. In the cylinder head 1, combustion chambers (not shown) are arranged in the longitudinal direction according to the arrangement of the cylinders. An intake port and an exhaust port (both not shown) are provided for each combustion chamber. In the upper part of the cylinder head 1, a valve train is provided for each intake port and each exhaust port, and the continuously variable valve train 2 acting on behalf of a throttle valve is provided to the valve train on the intake side. Is assembled.
[0016]
FIG. 2 shows a configuration of the continuously variable valve operating device 2 along the line AA in FIG. 1, FIG. 3 shows a cross-sectional view along the line BB in FIG. 1, and FIG. FIG. 6 shows a side view along the line C, and FIG. 6 shows an exploded view of the continuously variable valve train 2.
[0017]
2 and FIG. 6 shows a pair of intake valves (only one set is shown in FIG. 2 and FIG. 6) attached to the cylinder head 1 for each cylinder (for each combustion chamber). ).
[0018]
A rocker arm type valve structure using a rocker arm 5 is used for the intake valve 4 constituting the valve train. More specifically, the rocker arm 5 is formed of, for example, a substantially plate-shaped member extending in a direction perpendicular to the direction in which the cylinders are arranged. The end of the rocker arm 5 arranged on the center side of the combustion chamber is disposed above the cylinder head 1 along a support member, for example, a direction in which the cylinders are arranged as shown in FIGS. The rocker shaft 6 is swingably supported. The end of the opposite end of the combustion chamber is in contact with the end of a shaft 7a extending from a pair of umbrella-shaped valve bodies 7 reciprocally assembled to the intake port. The valve element 7 is urged by a valve spring (not shown) in the closing direction, here, upward, so as to always return to the closed state. A rocker arm roller 8 (corresponding to a roller) is rotatably mounted at the center of the intermediate portion of the rocker arm 5 in a direction in which the axis is parallel to the rocking axis of the rocker arm 5. Thus, when the rocker arm roller 8 is pressed from above, the rocker arm 5 swings and the valve body 7 in the closed state is opened. That is, the intake valve 4 has a structure in which the valve body 7 reciprocates due to the swing of the rocker arm 5, and the intake port is opened and closed.
[0019]
Reference numeral 10 denotes a variable valve mechanism constituting the continuously variable valve apparatus 2. The variable valve mechanism 10 is mounted immediately above the intake valve 4 for each cylinder as shown in FIGS. Each of these variable valve mechanisms 10 has the same structure. One of the structures will be described. Reference numeral 11 denotes a pair of wall-shaped holders (corresponding to the holding portion of the present application), which are located on both sides of the rocker arm 5 and erected above the cylinder head 1 for each cylinder. For example, a control shaft 13 disposed above the rocking fulcrum of the rocker arm 5 and disposed along the cylinder row direction, for example, disposed substantially above the rocking end of the rocker arm 5 and disposed along the cylinder row direction Camshaft. The holder 11 is fastened by, for example, a bolt member 11a (fastener) screwed into the cylinder head 1 from above. The camshaft 13 is in line with the control shaft 12. These shafts 12 and 13 rotatably pass through the respective holders 12 arranged for each cylinder. That is, the shafts 12 and 13 are rotatably supported by the holder 11. The rocker shaft 6 is also supported through the holder 11. The control shaft 12 is connected to a control drive source, for example, a control motor 14. Thus, the control shaft 12 is rotated by a desired amount of displacement by the operation of the control motor 14 (both clockwise and counterclockwise). The camshaft 13 is connected to a crankshaft (not shown) attached to a cylinder block (a part to be combined with the cylinder head 1) via a timing gear, a timing chain, and a crank gear (all not shown). is there. As a result, the camshaft 13 is driven to rotate (clockwise) by the crank output.
[0020]
Immediately above the rocker arm roller 8, as shown in FIGS. 2 and 6, for example, a swing lever 15 having a substantially L-shape is arranged. The swinging lever 15 has a lower portion extending in the lateral direction (the swinging fulcrum to the swinging end) along the rocker arm roller 8 as a short side, passes between the control shaft 12 and the crankshaft 13, and extends therebetween. A plate-like component having an upper portion extending upward as a longitudinal side is used. The lower end surface on the short side is in contact with the outer peripheral surface of the rocker arm roller 8. This short side lower end surface is used as a contact surface 16 for the rocker arm roller 8.
[0021]
The upper end of the swing lever 15 is adjacent to the control shaft 12, and the middle portion is adjacent to the camshaft 13. A holding shaft 17 formed of, for example, a short shaft member is fixed to the upper end of the swing lever 15 so as to penetrate in the cylinder row direction. The holding shaft 17 forms a swing fulcrum A at the upper end of the swing lever 15. This swing fulcrum A is, for example, using a pair of holding levers 18 arranged at a position adjacent to the swing lever 15 and has a radius centered on a position defining the state when the intake valve 4 is closed from both sides, It is swingably held between the control shaft 12 and the camshaft 13. Specifically, each of the pair of holding levers 18 is configured by an L-shaped lever member disposed between the swing lever 15 and each holder 11. Each of the holding levers 18 has a through hole 19 at an upper part as shown in FIG. 6, for example, and has a shaft part 20 projecting to the side parallel to the axis of the through hole part 19 at a lower part. An L-shaped lever member having a length from the swing fulcrum A to the center of the rocker arm roller 8 when the valve is closed is used from the center of the hole 19 to the center of the shaft 20 (FIG. 6 shows only one side). Not shown). The through holes 19 of the holding levers 18 are rotatably fitted to the ends of the holding shafts 17 of the swing lever 15 as shown in FIGS. Further, each shaft portion 20 is rotatably inserted into a support hole 21 formed at a lower portion of each holder 11 in accordance with the center position of the rocker arm roller 8 when the valve is closed, and closes the swing fulcrum A. The rocker arm roller 8 at the time can be moved around the center of the roller center.
[0022]
The outer peripheral surface of the upper end portion of the swing lever 15 is formed in a flat circular shape, and the contact surface 22 is formed on the outer peripheral surface. A cam surface (outer peripheral surface) of a plate-shaped eccentric cam 12a (corresponding to an eccentric body) provided eccentrically to the control shaft 12 is in contact with the contact surface 22 of the swing lever 15 from the lateral direction. Thus, when the eccentric cam 12a is eccentrically displaced, the swing fulcrum A of the swing lever 14 moves around the axis of the rocker arm roller 8 following the movement of the eccentric cam 12a.
[0023]
A roller 23 is provided on an intermediate portion of the swing lever 14 (the swing fulcrum A to the contact surface 16) on a side portion adjacent to the camshaft 13 so as to partially protrude. A cam surface (outer peripheral surface) of a drive cam 13a formed on the camshaft 13 and formed, for example, in a substantially triangular shape is brought into contact with the outer peripheral surface of the roller 23 from above. Thus, the rollers 23 are periodically pressed as the camshaft 13 rotates. Thus, the driving force required to open the intake valve 4 is input to the swing lever 14 from the driving cam 13a by using the roller 23 as an input unit.
[0024]
That is, when the swing fulcrum A of the swing lever 15 is moved by the eccentric displacement of the control shaft 12 while the swing lever 15 is swinging by the drive cam 13a, the tilt angle of the swing lever 15 changes, and the rocker arm roller The structure is such that the area of the abutment surface 16 that abuts on the surface 8 moves.
[0025]
On the control shaft 12 side of the contact surface 16, a base circle section corresponding to the base circle of the drive cam 13a is formed. The base circle section is formed on an arc surface having a base circle radius with a value obtained by subtracting the roller radius from the distance between the rocking fulcrum A and the center of the rocker arm roller around the rocking fulcrum A. On the opposite side of the camshaft 13, there is formed a lift section formed by an arc surface facing in the opposite direction. The lift section is formed by a circular arc for determining a valve lift amount of the intake valve 4 set in advance, and when the tilt angle of the swing lever 15 changes, the lift section between the base circle section where the rocker arm roller 8 moves and the lift section. By changing the ratio, the valve lift of the intake valve 4 can be continuously varied.
[0026]
That is, while the swing lever 15 is being swung by the drive cam 13a, the control motor 14 causes the eccentric cam 13a to be pivotally displaced so as to give the largest movement amount as shown in FIG. The swing fulcrum A of the lever 15 moves to the point farthest from the control shaft 12 around the axis of the rocker arm roller 8 when the valve is closed. Then, the swinging lever 15 is displaced in a direction in which the roller 23 serving as an input portion and the driving cam 13a come into contact with each other with the supporting point as a fulcrum. As a result, the rocker arm roller 8 crosses the area defined by the swing fulcrum of the swing lever 15, that is, the narrowest base circle section and the longest lift section as shown in FIG. 5A. Thus, control for ensuring the maximum valve lift is performed.
[0027]
When the eccentric cam 13a is rotated and displaced by the control motor 14 such that the eccentric cam 13a has the smallest movement amount as shown in FIG. 5B during the swing of the swing lever 15, the swing of the swing lever 15 is achieved. The fulcrum A moves about the axis of the rocker arm roller 8 when the valve is closed to the point closest to the control shaft 12. Then, the swing lever 15 is displaced in a tilting direction with the point where the roller 23 serving as the input portion and the drive cam 13a abut as a fulcrum. As a result, the rocker arm roller 8 crosses the area defined by the swing fulcrum of the swing lever 15, that is, the longest base circle section and the shortest lift section as shown in FIG. 5B. As a result, control for ensuring the minimum valve lift is performed. That is, the movement of the swing fulcrum A continuously controls the maximum valve lift amount to the minimum valve lift amount.
[0028]
As described above, during the swing of the swing lever 15, the swing fulcrum of the swing lever 15 is always fixed on the locus of an arc centered on the position that defines the valve closing state. The intake valve 4 can be reliably opened / closed at the intended opening / closing timing regardless of the large lift amount control indicated by X and the small lift amount control also indicated by Y. In addition, since each swing lever 15 is independently held for each cylinder by a holding lever 18 disposed adjacently, a shaft portion (holding shaft 17) from the swing fulcrum A to the end of the holding lever is held. Since they can be kept short, the rocking operation can be performed under a state where a high supporting strength is secured.
[0029]
Therefore, the opening and closing of the intake valve 4 can be controlled with high accuracy according to the set valve lift amount without hindering the engine from rotating at a high speed. In addition, the rocker arm type intake valve 4 is adopted, and the swing fulcrum A of the swing lever 15 can be freely moved around the axis of the rocker arm roller 8 by the holding lever 18, so that the swing can be performed with a simple structure. The swing fulcrum A of the lever 15 can be held with high rigidity and high accuracy. In addition, the structure in which the holding lever 18 adjacent to the swing lever 15 connects the swing fulcrum A of the swing lever 15 and the axis of the rocker arm roller 8 has a swing fulcrum that is not affected by peripheral components. A can be arranged at a position as low as possible, and there is an advantage that the total height of the engine can be suppressed.
[0030]
The present invention is not limited to the above-described embodiment, and may be implemented with various modifications without departing from the gist of the present invention. For example, in one embodiment, the structure in which the swing fulcrum of the swing lever is swingably supported from both sides by using a substantially L-shaped holding lever is described, but the swing lever is swingably swingable by another structure. A supporting structure may be used.
[0031]
【The invention's effect】
As described above, according to the first aspect of the present invention, regardless of the valve lift amount, the swing fulcrum of the swing lever is always held by the holding lever for each cylinder when the valve is closed. Since it is fixed on the reference trajectory, variations in the opening / closing timing of the reciprocating valve are eliminated. Moreover, since the swing levers are held independently of each other by holding levers arranged adjacent to each other, the portion from the swing fulcrum to the holding lever can be kept short, and both swing levers have high support strength. Can be swung under the condition of securing.
[0032]
Therefore, the opening and closing of the reciprocating valve can be controlled with high accuracy according to the set valve lift amount without hindering the engine from rotating at a high speed.
[0033]
According to the second aspect of the present invention, in addition to the above effects, the swing fulcrum of the swing lever can be held with high rigidity and high accuracy with a simple structure. In addition, the swing fulcrum can be arranged at a position as low as possible without being affected by the surrounding components, so that the overall height of the engine is suppressed and the engine can be made more compact.
[Brief description of the drawings]
FIG. 1 is a plan view showing a continuously variable valve train according to an embodiment of the present invention.
FIG. 2 is a side sectional view taken along the line AA in FIG.
FIG. 3 is a front sectional view taken along line BB in FIG. 1;
FIG. 4 is a side view taken along the line CC in FIG. 1;
FIG. 5A is a side view showing a state of a movable valve mechanism during maximum lift control.
(B) is a side view showing the state of the movable valve mechanism at the time of minimum lift control.
FIG. 6 is an exploded perspective view showing the structure of the continuously variable valve operating device.
FIG. 7 is a diagram showing control of a valve lift amount performed by the apparatus.
[Explanation of symbols]
4: Intake valve (reciprocating valve)
5 Rocker arm 6 Rocker shaft (support member)
7. Valve 8 Rocker arm roller (roller)
10: Variable valve mechanism 11: Wall-shaped holder (holding part)
12a: Eccentric cam (eccentric body)
13a Drive cam 15 Swing lever 16 Contact surface 17 Holding shaft 18 Holding lever 23 Roller (input unit).

Claims (2)

On an upper part of a cylinder head having a plurality of cylinders arranged in series and a reciprocating valve for each cylinder, an eccentric body capable of eccentric movement in a direction in which the cylinders are arranged and a drive cam driven to rotate are arranged in parallel with each other. A swinging lever is provided between the body and the drive cam, the swinging lever extending between and between the cylinders and between the two, and each swinging lever is provided at the lower end thereof with the reciprocating valve. An eccentric displacement of the eccentric body at an upper end thereof, and a swing fulcrum at which a position moves between the eccentric body and the drive cam at an upper end portion. An input section for inputting a driving force for opening the reciprocating valve from a driving cam, and when the oscillating fulcrum is moved, a contact surface that comes into contact with the reciprocating valve from a change in the inclination angle of the oscillating lever. Area moves to continuously vary the valve lift of the reciprocating valve Equipped with a cell variable valve mechanism,
In the upper part of the cylinder head, each cylinder is disposed so as to extend in the vertical direction at a position adjacent to the swing lever, and the upper end is rotatably supported at the swing fulcrum of the swing lever, and the lower end is Is provided with a holding lever rotatably supported at a position defining a state of the reciprocating valve at the time of closing the valve,
For each cylinder, each holding lever swings the swing fulcrum between the eccentric body and the drive cam around a position that defines the state of the reciprocating valve at the time of closing. A continuously variable valve operating device for an internal combustion engine, which is movably held. The reciprocating valve has a rocker arm having one end swingably supported by a support member and a rotatable roller abutting on the abutment surface at an intermediate portion, and a rocker arm swinging at the other end of the rocker arm. It is configured with a rocker arm type having a valve body that is opened and closed,
The holding lever is rotatably supported by a holding portion formed in the cylinder head at a shaft center position of the roller when the valve is closed at a lower end portion, and is rotatable at a swing fulcrum of the swing lever at an upper end portion. 2. The continuously variable valve operating device for an internal combustion engine according to claim 1, wherein the continuously variable valve operating device is constituted by a lever member supported by the lever.

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