JP2004132258A - 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 capable of controlling the opening and closing of a reciprocating valve with high accuracy in accordance with determined valve lifting amount. <P>SOLUTION: This continuously variable valve device is provided with a holding member 18 for holding an oscillation supporting point A of an oscillation lever 15 slidably along between a controlling eccentric cam 12a and a driving cam 13a on a shaft center position of a roller 8 in valve closing of a locker arm 5, and the oscillation supporting point A of the oscillation lever 15 is constantly fixed on a circular arc path on a position to regulate a valve close state during the oscillation of the oscillation lever 15, whereby the oscillation and displacement of the oscillation lever 15 can be constantly adjusted on the basis of valve closing, regardless of the valve lifting amount, and the variation of an opening and closing period of the intake valve 4 can be prevented. <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]
A gasoline engine (internal combustion engine) is equipped with a continuously variable valve operating system, in which the work of the throttle bubble (adjustment of the amount of intake air) is performed by a reciprocating valve on the intake side, that is, an intake valve, and a pump provided by the throttle bubble. Attempts have been made to reduce losses.
[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]
To this end, a control shaft formed of an eccentric body that can eccentrically move is arranged on one side of the upper side with the swing lever interposed, and a cam shaft is arranged on the intermediate part opposite to the control shaft with the swing lever interposed. 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, and the swing shaft can be opened from the input portion formed at the intermediate portion of the swing lever by the camshaft drive cam. A variable valve mechanism for inputting a necessary driving force to a valve is employed. 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]
Accordingly, an object of the present invention is to provide a continuously variable valve operating device for an internal combustion engine that can control a valve lift amount with high accuracy.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the swing fulcrum of the swing lever is moved between the eccentric body and the drive cam around a position defining the state of the reciprocating valve when the valve is closed. The swinging fulcrum of the swinging lever is positioned at a fulcrum position determined by the eccentric body by providing a holding means for swingably holding the swinging lever.
[0010]
With this configuration, even during swinging of the swing lever, the swing fulcrum of the swing lever is always fixed on a locus of an arc around the position that defines the valve-closed state. 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. .
[0011]
Therefore, the air amount can be finely adjusted, and the valve lift amount can be controlled with high accuracy.
[0012]
According to a second aspect of the present invention, in addition to the above object, one end of the reciprocating valve is swingably supported by a support member so that the swing fulcrum of the swing lever can be supported with high accuracy. A rocker arm type having a rocker arm that supports a rotatable roller that abuts on a contact surface with a portion, and a valve body that is opened and closed by swinging the other end of the rocker arm. The swing fulcrum of the swing lever is held so as to be able to swing between the eccentric body and the drive cam around the axial position of the roller when the valve is closed.
[0013]
According to a third aspect of the present invention, in addition to the above object, one end of the holding means is provided at the axial center position of the roller when the valve is closed so that the swing fulcrum of the swing lever can be supported with a simple structure. The holding lever was rotatably supported by the cylinder head, and the other end was rotatably supported by the swing fulcrum of the swing lever.
[0014]
According to a fourth aspect of the present invention, in addition to the above object, the contact surface of the rocking lever is formed by an arc surface centered on the rocking fulcrum of the rocking lever so that the valve lift can be favorably controlled. And a lift section continuously formed at a point adjacent to the base circle section.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described based on the first embodiment shown in FIGS.
[0016]
In FIG. 1, reference numeral 1 denotes a plane of a cylinder head of an internal combustion engine, for example, a multi-cylinder reciprocating gasoline engine. The cylinder head 1 is provided with a combustion chamber (not shown) for each cylinder along the longitudinal direction. An intake port and an exhaust port (both not shown) are provided for each combustion chamber. Above the cylinder head 1, a valve train is provided for each intake port and each exhaust port. Among these valve trains, a continuously variable valve train 2 which substitutes for the work of a throttle valve is mounted on a valve train on the intake side.
[0017]
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.
[0018]
2 and 6, reference numeral 4 denotes a pair of intake valves (only one set is shown: corresponding to a reciprocating valve) attached to the cylinder head 1 for each cylinder.
[0019]
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. An end portion of the rocker arm 5 arranged on the center side of the combustion chamber swings on a support member, for example, a rocker shaft 6 arranged along the direction in which the cylinders are arranged as shown in FIGS. 1, 2 and 4. It is freely supported. The end of the rocker arm 5 on the combustion chamber end side is in contact with the end of a shaft portion 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 by the swing of the rocker arm 5, and the intake port is opened and closed.
[0020]
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 which are located on both sides of the rocker arm 5 and are provided upright on the cylinder head 1 for each cylinder. The control shaft 13 located above and along the cylinder row direction is, for example, a camshaft located substantially above the swinging end of the rocker arm 5 and arranged along the cylinder row direction. 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.
[0021]
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.
[0022]
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. The swinging fulcrum A is connected to the control shaft 12 around a position defining the state when the intake valve 4 is closed from both sides by using a holding member as a holding means, for example, a pair of L-shaped holding levers 18. It is held swingably along with the camshaft 13. Specifically, for example, as shown in FIG. 6, the pair of holding levers 18 have a through hole 19 at an upper portion, and a lower portion has a shaft portion 20 protruding laterally in parallel with the axis of the through hole portion 19. 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 from the center of the through hole 19 to the center of the shaft 20 is used. 6 is only shown on one side). The through holes 19 of the holding levers 18 are rotatably inserted into the ends of the holding shafts of the swing lever 15 as shown in FIGS. 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 at the time of closing the valve. The rocker arm roller 8 can be moved around the center of the roller center.
[0023]
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.
[0024]
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.
[0025]
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.
[0026]
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 of an oppositely facing arcuate surface that follows the camshaft 13. 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.
[0027]
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.
[0028]
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.
[0029]
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 and closed at the intended opening / closing timing even when the large lift amount is controlled as indicated by X and when the small lift amount is controlled as indicated by Y. That is, no matter what valve lift amount is set, unintended opening / closing does not occur (elimination of variation).
[0030]
Therefore, the opening and closing of the intake valve 4 can be reliably controlled according to the set valve lift amount, the air amount can be finely adjusted, and the valve lift amount can be controlled with high accuracy. Moreover, when the rocking arm A of the rocking arm 15 is made movable around the axis of the rocker arm roller 8 by employing the rocker arm type intake valve 4, the rocking arm A of the rocking lever 15 is supported with high precision. And the valve lift amount can be controlled with higher accuracy. In particular, when a structure that supports the swing fulcrum A using the holding lever 18 is used, the swing fulcrum A can be supported with high accuracy with a simple structure. In addition, since the base circle section α centered on the swing fulcrum A of the swing lever 15 movably supported and the lift section β that follows the base circle section are employed, good control of the valve lift can be assured.
[0031]
FIG. 8 shows a second embodiment of the present invention.
[0032]
This embodiment is a modification of the first embodiment, and has a structure in which the upper end of the swing lever 15 and the eccentric cam 12a are brought into contact via a rotatable roller 25.
[0033]
More specifically, in the present embodiment, the roller 25 is rotatably supported around the holding shaft 17, and the outer peripheral surface of the roller 25 is brought into contact with the outer peripheral surface of the eccentric cam 12a.
[0034]
With such a structure, the contact surface pressure between the swing lever 15 and the eccentric cam 12a can be reduced, and the contact position of the swing fulcrum A of the swing lever 15 is not constant, and the rotation of the roller 25 Since it is changed by the displacement, there is an advantage that local wear is suppressed and the durability of the variable valve mechanism 10 is improved. Of course, the roller 25 may be provided on the eccentric cam 12a side.
[0035]
However, in FIG. 8, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
[0036]
Note that the present invention is not limited to the above-described embodiment, and may be implemented with various modifications without departing from the spirit of the present invention. For example, in the above-described embodiment, the structure in which the swing fulcrum of the swing lever is swingably supported using the substantially L-shaped holding lever has been described, but the swing lever is swingably supported by another structure. May be.
[0037]
【The invention's effect】
As described above, according to the first aspect of the present invention, the swing fulcrum of the swing lever is always fixed on the trajectory based on the closing time, regardless of the valve lift amount of any size. Therefore, variation in the opening / closing timing of the reciprocating valve is eliminated.
[0038]
Therefore, the reciprocating valve can be controlled to open and close accurately according to the set valve lift amount, and the valve lift amount can be controlled with high accuracy.
[0039]
According to the second aspect of the invention, in addition to the above-described effects, the swing fulcrum of the swing lever can be supported with high accuracy, and the valve lift can be controlled with high accuracy.
[0040]
According to the third aspect of the invention, in addition to the above-described effects, there is an effect that the swing fulcrum can be supported with high accuracy by a simple structure.
[0041]
According to the invention of claim 4, there is an effect that a good control of the valve lift can be performed.
[Brief description of the drawings]
FIG. 1 is a plan view showing a continuously variable valve operating device according to a first 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.
FIG. 8 is a front sectional view showing a continuously variable valve operating device according to a second embodiment of the present invention.
[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 12a Eccentric cam (eccentric body)
13a Drive cam 15 Swing lever 16 Contact surfaces 17, 18 Holding shaft, holding lever (holding means)
23 ... roller (input unit).

Claims (4)

An eccentric body capable of eccentric movement and a rotationally driven drive cam are arranged in parallel, and between the eccentric body and the drive cam, there is a swing lever extending between them, and the swing lever is An end surface of one end portion having an abutment surface for abutting on a reciprocating valve, and the other end of the swing lever receiving the eccentric displacement of the eccentric body to move the position between the eccentric body and the drive cam. An input portion for inputting a driving force to open the reciprocating valve from the drive cam at an intermediate portion of the swing lever, and when the swing support point is moved, the swing lever A region of the contact surface that comes into contact with the reciprocating valve moves from a change in the inclination angle of the reciprocating valve, and includes a variable valve mechanism that continuously varies a valve lift amount of the reciprocating valve,
The swing lever can swing a swing fulcrum of the swing lever along a position between the eccentric body and the drive cam around a position defining a state of the reciprocating valve when the valve is closed. A continuously variable valve operating device for an internal combustion engine, wherein a holding means for holding the internal combustion engine is provided. 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 means is configured to hold a swing fulcrum of the swing lever around a shaft center position of the roller when the valve is closed along a space between the eccentric body and the drive cam. 2. The continuously variable valve operating apparatus for an internal combustion engine according to claim 1, wherein: The holding means has one end rotatably supported by the cylinder head at the axial position of the roller when the valve is closed, and the other end rotatably supported by a swing fulcrum of the swing lever. 3. The continuously variable valve operating apparatus for an internal combustion engine according to claim 2, comprising a lever. The contact surface of the swing lever has a base circle section formed by an arc surface centered on the swing fulcrum of the swing lever, and a lift formed at a point adjacent to the base circle section continuously to the base circle section. 4. The continuously variable valve operating device for an internal combustion engine according to claim 1, wherein the continuously variable valve operating device is formed with a section.

Images