JPH108930A - Variable valve system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make valve lifting quantity sharply adjustable by slight moving adjustment, by interposing a sub-arm, extending toward the base end of a locker member, between a rotation cam and the locker arm, and also a transmitting top, movable in the extending direction of both the arms between the sub-arm and the locker arm. SOLUTION: When the pistons 31 and 32 of a hydraulic cylinder mechanism 30 move transmitting members 16 and 26 respectively in the range of virtual line positions from the solid line positions, the positions of the respective transmitting members 16 and 26 move against sub-arms 15 and 25 and locker arms 14 and 24, to be changed, and this changes the length, from the oscillation centers of the sub-arms 15 and 25 to the engaging positions with the transmitting members 16 and 26, also the length from the oscillation centers of the locker arms 14 and 24 to the engaging positions with the transmitting tops 16 and 26. Consequently, the oscillation quantity, of the locker arms 14 and 24 to that of the sub-arms 15 and 25 due to the rotation of rotating cams 11 and 21, is changed, thereby changing the lifting quantity of valves 12 and 22 due to the locker arms 14 and 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve mechanism capable of adjusting a lift amount of a valve (an intake valve or an exhaust valve) that is opened and closed in synchronization with a crankshaft in an internal combustion engine.

[0002]

2. Description of the Related Art As one of the variable valve mechanisms, a rotary cam which is rotated in synchronization with a crankshaft of an internal combustion engine, a rocker arm which is swung by the rotation of the rotary cam and lifts a valve is provided. There is a variable mechanism for varying the rocking amount of the rocker arm caused by the rotation of the rotary cam so that the lift amount of the valve can be adjusted. For example, this is disclosed in Japanese Patent Application Laid-Open No. 7-11921.

[0003]

In the variable valve mechanism disclosed in the above-mentioned publication, the variable mechanism is swingably assembled to rotatably support the rotary cam and swings the rotary cam along the rocker arm. It has a movable support arm and a servo motor that swings this support arm, and the servo motor swings the support arm and moves the rotary cam along the rocker arm, so that the rotary cam and Since the valve lift amount is adjusted by changing the engagement position with the rocker arm, to increase the adjustment width of the valve lift amount, increase the swing amount of the support arm by the servo motor,
It is necessary to increase the amount of position movement of the rotary cam, and when it is incorporated in a cylinder head, it is disadvantageous in terms of space.
Further, since the position of the rotary cam moves, not only the structure of the mechanism for rotating the rotary cam in synchronization with the crankshaft of the internal combustion engine becomes complicated, but also reliability becomes a problem.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to address the above-described problems, and has a rotating cam that is rotated in synchronization with a crankshaft of an internal combustion engine, and a swing cam that is rotated by the rotation of the rotating cam. A rocker arm for lifting the valve, and a variable mechanism for varying a swing amount of the rocker arm by rotation of the rotary cam, wherein the variable valve mechanism capable of adjusting the lift amount of the valve, A mechanism is disposed between the rotating cam and the rocker arm, extends from the swinging end side of the rocker arm toward the base end of the rocker arm, overlaps the rocker arm by a predetermined amount at a predetermined interval, and overlaps the rotation cam by a predetermined amount. A sub-arm that is swung about a base end by rotation,
A transmission piece that is assembled between the sub arm and the rocker arm so as to be able to advance and retreat in the extending direction of the two arms and that transmits the swing of the sub arm as the rocker arm, and a driving unit that moves the transmission piece forward and backward; The configuration was provided with.

In this case, the rotating cam, the valve, the rocker arm, the sub arm, and the transmission piece may be symmetrically arranged in a pair, and a single hydraulic cylinder mechanism may be used as the driving means.

[0006]

In the variable valve mechanism according to the present invention, when the transmission piece is moved forward and backward by the drive means, the position of the transmission piece moves and changes with respect to the sub arm and the rocker arm, and changes from the swing center of the sub arm. The length from the swing center of the rocker arm to the engagement position with the transmission piece changes along with the length to the engagement position with the transmission piece, and the swing amount of the sub-arm due to the rotation of the rotation cam (the rotation cam and The swing amount of the rocker arm changes with respect to the amount determined by the shape of the sub arm and does not change due to the position movement of the transmission piece, and the lift amount of the valve by the rocker arm changes.

When the transmission piece moves forward and backward, the length of the transmission arm relative to the sub-arm increases from the swing center of the sub-arm to the position where the transmission arm engages with the transmission piece. The length to the engagement position with the transmission piece decreases,
Also, when the length of the sub-arm from the swing center to the engagement position with the transmission piece decreases due to the movement of the transmission piece with respect to the sub-arm, the length of the transmission piece with respect to the rocker arm decreases from the swing center of the rocker arm to the engagement position with the transmission piece. The lever ratio (input / output displacement ratio) of the sub arm and rocker arm changes respectively in the opposite direction,
The lift amount of the valve due to the rotation of the rotary cam changes synergistically. Therefore, the swing amount of the rocker arm, that is, the lift amount of the valve can be largely changed by a slight movement of the transmission piece, which is advantageous in terms of space.

In the variable valve mechanism according to the present invention, since the position of the rotary cam is fixed, the structure of the mechanism for rotating the rotary cam in synchronization with the crankshaft of the internal combustion engine is not complicated, and the rotary cam is not rotated. The power is transmitted by a simple mechanism in which the sub-arm is swung by the rotation of the cam and the swing of the sub-arm is transmitted as the rocker arm by the transmission piece, so that the reliability is high. Further, since the moving direction of the transmission piece is the direction in which the sub arm and the rocker arm extend and the direction perpendicular to the direction in which the force is transmitted from the sub arm to the rocker arm, the transmission piece does not move unnecessarily, and the transmission piece does not move. Position holding can be performed with a small force.

In the present invention, when a rotary cam, a valve, a rocker arm, a sub-arm, and a transmission piece are symmetrically arranged in a pair and a single hydraulic cylinder mechanism is used as a driving means of the transmission piece, the mechanism may be used. Simplification is possible, and reduction in size and weight can be achieved.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a variable valve mechanism embodying the present invention. The variable valve mechanism is a pair of rotary cams known per se that are rotated in synchronization with a crankshaft (not shown) of the internal combustion engine. 11 and 21 (integrally formed on a camshaft rotatably mounted on the cylinder head 41),
Each of the valves 12 and 22 (the valve shown as a whole is an intake valve, and the partially omitted valve is an exhaust valve) is swung by the rotation of the valve spring 13,
A pair of rocker arms 14 and 24 (known as a support shaft 42,
43) and rocker arms 14, 24 by rotation of the rotary cams 11, 21.
Are provided with variable mechanisms S1 and S2 for varying the amount of swing of.

Each of the variable mechanisms S1, S2 includes a rotating cam 11,
A sub-arm 15, which is disposed between the rocker arm 21 and the rocker arms 14 and 24 and is swung by rotation of the rotary cams 11 and 21;
25, sub-arms 15, 25 and rocker arms 14, 2
The transmission piece 16, which is assembled between the four and transmits the swing of the sub-arms 15, 25 as the swing of the rocker arms 14, 24,
26, and a single hydraulic cylinder mechanism 30 as drive means for moving the transmission pieces 16, 26 forward and backward.

Each of the sub arms 15 and 25 is
The rocker arms 14 and 24 are swingably mounted to the cylinder head 41 via support shafts 44 and 45 between the rocker arms 14 and 24. 43), extending toward the base end of the rocker arms 14, 24 as the rocker arms 14, 24).
24 are polymerized at predetermined intervals at predetermined intervals.
It is engaged with the rotating cams 11 and 21 via rollers 18 and 28 rotatably assembled via 27. Further, each sub-arm 15, 25 is engaged with a well-known lost motion mechanism 50, 60 for the purpose of reducing the inertial mass of the valve train, so that the load on the valve springs 13, 23 is reduced. It is being rushed.

Each of the transmission pieces 16, 26 includes a sub-arm 15,
25 and rocker arms 14, 24, both arms 15, 2
5, 14, and 24, which are assembled so as to be able to advance and retreat in the extending direction, and are pivotally connected to the respective pistons 31 and 32 of the hydraulic cylinder mechanism 30 via pins 19 and 29 at the base end. The pistons 31 and 32 move forward and backward between the sub-arms 15 and 25 and the rocker arms 14 and 24 by axial movement.

The hydraulic cylinder mechanism 30 includes a piston 3
Cylinder 33 accommodating 1, 32 slidably in the axial direction
And springs 35 that urge the pistons 31 and 32 toward the illustrated position. The hydraulic pressure supplied through an oil passage 49 provided in the cylinder head 41 and the spring force of the springs 34 and 35 provide Each piston 31, 3
2 is controlled. The oil pressure supplied through the oil passage 49 is output by an output detection sensor (not shown) for detecting a change in the output of the internal combustion engine, a position detection sensor (not shown) for detecting the moving position of the transmission pieces 16 and 26, When the two sub-arms 15 and 25 are not swung by the two rotation cams 11 and 21 based on a detection signal from a rotation angle detection sensor (not shown) that detects the rotation angle of the rotation cams 11 and 21 (for example, FIG. (When both valves 12 and 22 are closed as in the state shown in FIG. 3), feedback control is performed by a hydraulic control device (not shown), and both valves 12 and 22 are changed according to the output change of the internal combustion engine. , 22 are optimally controlled.

In the variable valve mechanism of the present embodiment constructed as described above, the two pistons 31, 32 of the hydraulic cylinder mechanism 30 move the transmission pieces 16, 26 from the solid line position in FIG. When moving forward and backward, each transmission piece 1
6 and 26 are moved relative to the sub-arms 15 and 25 and the rocker arms 14 and 24 and changed.
The length from the swing center of the rocker arms 5 and 25 (the center of the support shafts 44 and 45) to the engagement position with the transmission pieces 16 and 26 changes, and the swing center of the rocker arms 14 and 24 (the support shafts 42 and 45).
The length of the sub-arms 15 and 25 due to the rotation of the rotary cams 11 and 21 (the rotary cams 11 and 21 and the sub-arms 15 and 25) changes in length from the center of the rotation arm 43 to the engagement position with the transmission pieces 16 and 26. The swing amount of the rocker arms 14 and 24 changes with respect to the amount which does not change due to the position movement of the transmission pieces 16 and 26). Lift amount L1 indicated by a solid line in FIG.
(The lift amount when both transmission pieces 16 and 26 are at the solid line position in FIG. 1 and the lift amount shown in FIG. 2 is the maximum lift amount). Quantity L
2 (the lift amount when both transmission pieces 16 and 26 are at the imaginary line position in FIG. 1 and the lift amount shown in FIG. 3 is the maximum lift amount).

When the transmission pieces 16 and 26 move forward and backward, the transmission pieces 16 and 26 move from the swing center of the sub-arms 15 and 25 to the engagement position with the transmission pieces 16 and 26 due to the movement of the transmission pieces 16 and 26 with respect to the sub-arms 15 and 25. When the transmission pieces 16 and 26 move with respect to the rocker arms 14 and 24, the transmission pieces 1 move from the swing center of the rocker arms 14 and 24 when the transmission pieces 1 and 26 move.
The length of the transmission pieces 16, 26 relative to the sub-arms 15, 25 is reduced by the movement of the transmission pieces 16, 26 with respect to the sub-arms 15, 25.
When the length to the engagement position with the transmission piece is reduced,
The movement of the rocker arms 14 and 24 with respect to the rocker arms 14 and 24 increases the length from the rocking center of the rocker arms 14 and 24 to the engagement position with the transmission pieces 16 and 26.
The lever ratio (input / output displacement ratio) of the rocker arm 25 and the rocker arms 14 and 24 changes in the opposite direction.
The lift amounts of the valves 12 and 22 caused by the rotation of the rotation of the motors 21 and 21 change synergistically. Therefore, the swing amount of the rocker arms 14, 24, that is, the lift amount of the valves 12, 22 can be largely changed by a slight movement of the transmission pieces 16, 26, which is advantageous in terms of space.

In the variable valve mechanism according to the present embodiment, since the positions of the rotary cams 11 and 21 are fixed, the structure of the mechanism for rotating the rotary cams 11 and 21 in synchronization with the crankshaft of the internal combustion engine is as follows. The sub-arms 15 and 25 are swung by the rotation of the rotary cams 11 and 21, and the swing of the sub-arms 15 and 25 is transmitted by the transmission piece 1.
Since the force is transmitted by a simple mechanism such as the rocker arms 14 and 24 being rocked by the rockers 6 and 26, the reliability is high. Further, the moving direction of the transmission pieces 16 and 26 is determined by the sub-arms 15 and 25 and the rocker arm arms 14 and 25.
24, which is perpendicular to the direction of force transmission from the sub-arms 15, 25 to the rocker arms 14, 24, the transmission pieces 16, 26 do not move unnecessarily. The positions of the substrates 16 and 26 can be held with a small force.

In the variable valve mechanism of the present embodiment, the moving direction of the transmission pieces 16 and 26 is
5 and the rocker arms 14 and 24 in the extending direction.
The movement position is controlled by the hydraulic pressure feedback-controlled by the hydraulic control device and the spring force of each of the springs 34 and 35 when the transmission pieces 16 and 26 are not oscillated. The driving force of the hydraulic cylinder mechanism 30 may be small, and the movement of each of the transmission pieces 16 and 26 can be performed smoothly.

In the variable valve mechanism of the present embodiment, the rotary cams 11 and 21, valves 12 and 22, rocker arms 14 and 24, sub-arms 15 and 25, transmission piece 16,
26 are arranged symmetrically, and a single hydraulic cylinder mechanism 30 is employed as a driving means of the transmission pieces 16 and 26. Therefore, the variable valve mechanism can be simplified, and the size and weight can be reduced. be able to.

In the above embodiment, the two transmission pieces 16, 26 are moved by the single hydraulic cylinder mechanism 30, but each transmission piece 16, 26 is moved by each driving means (a motor other than the hydraulic cylinder mechanism, etc.). It is also possible to implement the present invention in such a way that each of them is moved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a main part showing an embodiment of a variable valve mechanism according to the present invention.

FIG. 2 is an operation explanatory diagram in a state where the transmission piece shown in FIG. 1 is at a solid line position.

FIG. 3 is an operation explanatory diagram in a state where the transmission piece shown in FIG. 1 is at a virtual line position.

4 is a characteristic diagram showing a relationship between a rotation amount of a rotary cam and a valve lift amount in a state where a transmission piece is at a solid line position and a virtual line position in FIG.

[Explanation of symbols]

11, 21 ... rotating cam, 12, 22 ... valve, 13, 2
3 ... valve spring, 14, 24 ... rocker arm, 1
5, 25: sub arm, 16, 26: transmission piece, 30: hydraulic cylinder mechanism (drive means), 31, 32: piston,
33 ... cylinder, 34, 35 ... spring, S1, S2
... variable mechanism.

Claims (2)

[Claims] A rotating cam that rotates in synchronization with a crankshaft of an internal combustion engine; a rocker arm that is swung by the rotation of the rotating cam to lift a valve; and the rocker arm swings due to rotation of the rotating cam. A variable valve mechanism having a variable mechanism for varying the amount of movement, the lift amount of the valve being adjustable, wherein the variable mechanism is disposed between the rotating cam and the rocker arm, and the rocker arm swinging end side. A base arm extending toward the base end of the rocker arm with a predetermined amount overlapping at a predetermined interval on the rocker arm and swinging about the base end by rotation of the rotary cam, and between the sub arm and the rocker arm The sub-arm swings as the rocker arm swings and is mounted so as to be able to advance and retreat in the extending direction of these two arms. A variable valve mechanism, comprising: a transmission piece that reaches; and driving means for moving the transmission piece forward and backward. 2. The rotary cam, a valve, a rocker arm,
2. The variable valve mechanism according to claim 1, wherein a pair of sub-arms and transmission pieces are symmetrically arranged, and a single hydraulic cylinder mechanism is employed as the driving means.