JPH063128B2 - Valve drive controller for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a valve operating system for an internal combustion engine.

<Prior Art> As a conventional valve operating system for an internal combustion engine, two cylinders are provided for each cylinder.
One intake valve is provided, and the lift amount and opening period of each of the two intake valves are controlled to be increased or decreased according to the engine operating conditions. And the lift amount and the opening period are increased on the high rotation and high load side (Japanese Patent Laid-Open No. 58-25537).
issue).

<Problems to be Solved by the Invention> However, in such a conventional valve operating system for an internal combustion engine, the lift amount of the intake valve and the lift amount of the intake valve are kept constant while the opening phases of the intake valve and the exhaust valve are kept constant. Since only the open period was controlled, it was not always the optimum control, and it was seen from the viewpoint of achieving stability at low and medium speeds and low and medium loads, and achieving high torque output at high speeds and high loads. I still had a problem.

In view of such a point, the present invention has an object to optimally control the valve opening phases of the intake valve and the exhaust valve according to the engine operating conditions.

<Means for Solving Problems> Therefore, according to the present invention, one cylinder is provided with at least two intake valves and one exhaust valve, and the lift amount and open period of each of the two intake valves are set to the engine. In an internal combustion engine equipped with a lift amount control device that controls increase / decrease according to operating conditions, the phase between the drive cam shafts of the intake valve and the exhaust valve and its drive system is controlled to allow intake at low and medium speeds and low and medium loads. A phase control device for delaying the valve opening phase of the valve and the exhaust valve and advancing the valve opening phase of the intake valve and the exhaust valve at the time of high rotation and high load is provided.

<Operation> In the above configuration, by delaying the opening phase of the exhaust valve and the intake valve during low and medium speed low and medium load, the closing timing of the exhaust valve is delayed from the top dead center to increase the residual gas, NO
_x can be reduced. Further, the swirl can be strengthened by delaying the opening timing of the intake valve and increasing the negative pressure at the start of intake. In addition, it is possible to reduce the pump loss by delaying the closing timing of the intake valve from the bottom dead center and discharging what has once been sucked.

On the other hand, at high rotation speed and high load, the opening phase of the exhaust valve and the intake valve is advanced to return to the normal state, thereby reducing residual gas and improving combustion, achieving high charging efficiency and high torque output. Obtainable.

<Example> An example of the present invention will be described below with reference to the drawings.

Referring to FIG. 3, the combustion chamber 1 of each cylinder is provided with two main and sub intake ports 2 and 3 and one exhaust port 4.
Further, two main and sub intake valves 5, 6 and one exhaust valve 7 are provided. The intake valves 5 and 6 and the exhaust valve 7 are driven by respective cams mounted on the same cam shaft.

Here, with respect to the intake valves 5 and 6, the lift amount and the open period are made variable by the lift amount control device 10 as shown in FIGS.

The lift amount control device 10 for the intake valve 5 will be described as a representative.
A rocker arm 13 is provided with both ends abutting against the cam 11 and the stem end of the intake valve 5, and a curved rear surface 13a of the rocker arm 13 is swingably supported at one end by a hydraulic pivot 19 described later. It is in fulcrum contact with the lever 15 that has been pressed. The lever 15 holds a shaft 13b protruding from both side walls of the rocker arm 13 in a groove 15a via a holding member 14, and between the spring seat 15b formed on the lever 15 and the holding member 14. A spring 16 having a small spring constant is interposed to bias the rocker arm 13 downward.

The hydraulic pivot 19 includes an outer cylinder 19a slidably fitted in a mounting hole 18a formed in a bracket 18 mounted on the cylinder head, and an inner cylinder 19b fitted in the outer cylinder 19a. A check valve 19d is provided in a hydraulic chamber 19c formed between the two. The hemispherical lower end of the outer cylinder 19a is fitted into the recess 15c on the upper surface of the one end of the lever 15 on the side of the intake valve 5 stem end, and the lever 15 is swingably supported. Then, from the hydraulic pressure supply passage 18b formed inside the bracket 18 to the inside of the inner cylinder 19b and the check valve 19b.
Hydraulic pressure is supplied to the hydraulic chamber 19c via d to keep the valve clearance constant.

A lift control cam 20 rotatably attached to the bracket 18 is engaged with the upper surface of the other end of the lever 15 on the cam 11 side to regulate the swing position of the lever 15. .

The lift control cam 20 has a polygonal shape and has a plurality of substantially flat cam surfaces 20a to 20e having different heights so as to change the lift amount of the intake valve 5 in a stepwise manner. It has a hole 20g for inserting. In addition, a cylindrical portion 20h formed by projecting from both ends of the lift control cam 20
Is a lower circular arc groove 18c formed in the bracket 18 and an upper circular arc groove 22 formed in a pair of caps 22 fastened on the bracket 18 with bolts 21 as shown in FIGS.
It is held rotatably between a and a.

Then, one control shaft 23 is inserted in a clearance fit state into a hole 20g formed through the central portion of the lift control cam 20 provided in several cylinders, and the control shaft 23 is provided on both sides of each lift control cam 20. One end of each of the twisted coil springs 24 inserted is locked to a stop screw 23a screwed onto the outer peripheral surface of the control shaft 23, and the other end of the coil spring 24 is lifted by the lift control cam 20.
It is fitted and locked in a hole 20i formed in the end surface of the cylindrical portion 20h.

One end of the control shaft 23 is connected to the stepping motor via a joint 25.
It is connected to a drive shaft 26a of 26. In this way, the control shaft 23 is rotated by the stepping motor 26 to a predetermined rotation position.

29 is a valve spring.

Therefore, when the lift control cam 20 is in contact with the lever 15 on the cam surface 20a having the largest lift amount,
15 is in the most depressed state toward the cam 11 side. Therefore, the lever that is in fulcrum contact with the back surface 13a of the rocker arm 13
The lower surface of 15 is also lowered, and the fulcrum contact point A is transmitted to the intake valve 5 while moving to the cam 11 side, the lift amount is large and the valve opening timing is early and the valve closing timing is large as shown by [large] in FIG. Has slow characteristics.

On the other hand, when the lift control cam 20 is rotated so as to contact the lever 15 with the cam surface 20e having the smallest lift amount, the end of the lever 15 on the cam 11 side is swung with the recess 15c as a fulcrum. Ascends, and the lower surface of the lever 15 also retracts upward.

The lower surface of the lever 15 serves as a fulcrum for the rocker arm 13 to transmit to the lift intake valve 5 of the cam 11, but the initial position of the fulcrum when the cam 11 is in contact with the rocker arm 13 in the base circle has a large lift amount. Compared to when the lever 15 is in contact with the cam surface 20a, the lever 15 moves to the right in FIG. 4, that is, to the side away from the direction in which the fulcrum moves after lifting. As a result,
As shown by [minimum] in FIG. 7, the lift amount is small, and the valve opening timing is delayed and the valve closing timing is advanced.

In this way, the lift control cam 20 is rotated to rotate the cam surface 20.
The lift characteristic of the intake valve 5 can be changed stepwise by bringing one of a to 20e into contact with the lever 15.

Here, the rotation of the lift control cam 20 is performed by driving the stepping motor 26 via the control shaft 23 and the torsion coil spring 24.

Now, at the timing when the control shaft 23 rotates, in the cylinder in which the intake valve 5 is being lifted, the rocker arm 13 and the lever 15
The contact fulcrum with and moves to the cam 11 side, and a large reaction force of the valve spring 29 acts on the lift control cam 20 via the rocker arm 13 and the lever 15. Therefore, while the lift control cam 20 remains fixed, only the control shaft 23 rotates while twisting the torsion coil springs 24 on both sides thereof. Next, after the cam 11 rotates and the intake valve 5 closes, the rocker arm 13
Since the contact fulcrum between the lever 15 and the lever 15 is located substantially above the intake valve 5 and the reaction force of the valve spring 29 disappears, the force acting on the lift control cam 20 is the same as the rocker arm 13
There is only a weak force of the spring 16 mounted between the lever and the lever 15. Therefore, during the lift of the intake valve 5, the torque stored in the torsion coil spring 24 is
The lift control cam 20 can be rotated by overcoming the weak force of 16.

Next, the phase control device 40 for controlling the valve opening phase (rotational phase of each drive cam) of the intake valves 5, 6 and the exhaust valve 7 will be described.

That is, as shown in FIG. 1, a timing pulley 38 is connected to one end of a cam shaft 37 having cams 11 (not shown) for driving the intake valve 6 and the exhaust valve 7 in addition to the cam 11 for driving the intake valve 5. The timing pulley 38 is interlocked with an unillustrated engine crankshaft via a timing belt 39 with teeth. Then, a phase controller 40 for controlling the rotational phase of the cam 11 and the like is incorporated in the connecting portion (fixing portion) between the timing pulley 38 and the cam shaft 37.

The phase control device 40 slidably reciprocates in an annular cylinder 38A formed in the timing pulley 38 to define a hydraulic chamber 41 in the cylinder 38A.
And a slider 44 that abuts against the piston 42 and slides along the cam shaft 37 against the biasing force of the coil spring 43 due to the reciprocating motion of the piston 42, and the movement of the slider 44 is restricted via the coil spring 43. It has a stopper member 45 fixed to the end surface of the cam shaft 37 with a bolt 50.
As shown in FIG. 2, the slider 44 has a twisted spline 44A formed on the inner surface of its hollow portion, a flange portion 44B with which the piston 42 abuts, and a cylinder 38A at the other end. Protrusions 44C slidably supported in a single groove 38B formed on the inner wall are formed. As shown in FIG. 2, a twist spline 37A is formed at one end of the cam shaft 37. The twist spline 37A is a twist spline of the slider 44.
It is designed to mesh with 44A.

In FIG. 1, reference numeral 46 denotes a hydraulic passage formed in the cam shaft 37 and the timing pulley 38. One end of the hydraulic passage 46 communicates with the hydraulic chamber 41, and the other end communicates with an external hydraulic supply passage 47. is doing. The other end of the hydraulic pressure supply passage 47 is branched into two on the way, and one passage 47A is connected to the oil pump 48.
The other passage 47B communicates with the hydraulic control valve 49. The hydraulic control valve 49 is electromagnetically actuated and controls the hydraulic pressure supplied from the oil pump 48 to the hydraulic chamber 41 in response to an electric signal.

Therefore, the hydraulic control valve 49 controls the hydraulic pressure to the hydraulic chamber 41, and the slider 44 is axially positioned according to the hydraulic pressure. Then, the torsion splines 37A and 44A slide in the axial direction corresponding to the position of the slider 44, whereby the cam shaft 37 rotates by a predetermined amount, thereby controlling the rotational phase of the cam 11 and the like.

Next, control according to the engine operating conditions of the lift amount control device 10 and the phase control device 40 will be described.

In FIG. 1, reference numeral 60 denotes a control circuit, which receives signals from a rotation speed sensor 61 for detecting an engine speed N and a throttle sensor 62 for detecting a throttle opening α, and based on these signals, a stepping motor 26 , 26 'and hydraulic control valve 49
Control the operation of. Reference numeral 26 'is a stepping motor for controlling the lift amount of the intake valve 6.

This control is performed according to the flow chart of FIG. 8, and the engine speed N is detected based on the signal from the speed sensor 61 in step 1 (denoted as S1 in the drawing; the same applies hereinafter), and the throttle sensor 62 detects the engine speed N. The throttle opening α is detected based on the signal Next, on the basis of N and α detected in step 2, a search is made for where in a predetermined area of ~ on a map where N is the horizontal axis and α is the vertical axis as shown in FIG. Then, in step 3, the stepping motor 26, based on the control mode corresponding to each area,
The lift amount of the intake valves 5, 6 is controlled via 26 ', and the opening phase of the intake valves 5, 6 and exhaust valve 7 is controlled via the hydraulic control valve 49.

Here, in the map of FIG. 9, except for the idle area, the lift amount control of the intake valves 5 and 6 is divided by broken lines [large-small], [small-small], [small-small]. Medium-
Intake valves 5 and 6 are divided into four areas, Medium and Large.
Further, the valve opening phase control of the exhaust valve 7 is divided into two areas of [delay] and [advance] so as to be divided by a hatched line, and is divided into areas of ~ by these.

Explaining the control mode for each area, as shown in FIG. 10, in each area, that is, at the time of idling, the lift amounts of the intake valves 5 and 6 are both controlled to a minimum, and the intake valves 5 and 6 and the exhaust valve are controlled. The valve opening phase of 7 is advanced.

In this state, since the lift amount is small, the friction of the valve train is reduced. In addition, the exhaust valve 7 opens considerably earlier than the end of the explosion stroke (bottom dead center), and the valve closing timing becomes earlier, so that it is almost the same as the end of the exhaust stroke (top dead center).
Although the residual gas decreases and combustion decreases, it is canceled by the fact that the exhaust valve 7 opens earlier and the exhaust temperature rises.

Area, that is, at low rotation and low load, as shown in FIG. 11, the lift amount of the intake valve 5 is controlled to be large and the lift amount of the intake valve 6 is controlled to be minimum, and the intake valves 5, 6 and the exhaust valve are controlled. 7 delays the valve opening phase.

In this way, the intake air is mainly introduced from one intake valve 5 to form a swirl in the combustion chamber 1 to improve the combustibility.
Further, by delaying the closing timing of the exhaust valve 7 to make it later than the top dead center, the residual gas is increased and NO _X is reduced. Further, the swirl is further strengthened by delaying the opening timing of the intake valves 5 and 6 to increase the negative pressure at the start of intake. Further, by delaying the closing timing of the intake valves 5 and 6 so as to be considerably later than the bottom dead center, the intake air that has been once sucked is discharged in the compression stroke, and the pump loss is reduced.

During medium rotation and medium load, it is divided into areas
12, the lift amounts of the intake valves 5 and 6 are both controlled to be small, and the opening phases of the intake valves 5 and 6 and the exhaust valve 7 are delayed. In the area of the 13th
As shown in the figure, the lift amounts of the intake valves 5 and 6 are both controlled to the inside, and the opening phase of the intake valves 5 and 6 and the exhaust valve 7 is delayed. 14, the lift amounts of the intake valves 5 and 6 are both controlled to be large, and the opening phases of the intake valves 5 and 6 and the exhaust valve 7 are delayed.

During high rotation and high load, it is divided into areas.

Area, that is, at low rotation and high load, both the lift amounts of the intake valves 5 and 6 are controlled to be small and the opening phases of the intake valves 5 and 6 and the exhaust valve 7 are advanced as shown in FIG. . 16, that is, at the time of high load in the middle rotation, as shown in FIG. 16, the lift amounts of the intake valves 5 and 6 are both controlled to the inside, and the opening phases of the intake valves 5 and 6 and the exhaust valve 7 are advanced. . In this area, that is, at the time of high rotation, as shown in FIG. 17, both the lift amounts of the intake valves 5 and 6 are controlled to be large, and the opening phases of the intake valves 5 and 6 and the exhaust valve 7 are advanced.

In this way, at the time of high rotation and high load, the lift amount of the intake valves 5, 6 is controlled to an optimum one according to the engine speed to obtain high charging efficiency and high torque output, while the intake valves 5, 5 are obtained.
The opening phase of 6 and the exhaust valve 7 is returned to the advanced side, in other words, returned to the normal state, and the swirl is reduced.

<Effects of the Invention> As described above, according to the present invention, the valve opening phases of the intake valve and the exhaust valve can be appropriately controlled according to the engine speed and the load, and the stability at low and medium speeds and low and medium loads can be achieved. The effect that the high torque output at the time of high rotation and at the time of high load is greatly improved can be obtained.

[Brief description of drawings]

1 is a sectional view of a phase control device showing an embodiment of the present invention, FIG. 2 is an exploded perspective view of a slider and a cam shaft end portion in FIG. 1, and FIG. 3 is a schematic view of a combustion chamber. 4 is a sectional view of the lift amount control device, FIG. 5 is a plan view of FIG. 4, FIG. 6 is a perspective view of a portion of the lift control cam, and FIG. 7 is a diagram showing the lift characteristics of the intake valve. FIG. 8 is a flow chart showing the contents of control, FIG. 9 is a diagram showing the mode of control corresponding to the area of engine operating conditions, and FIGS. 10 to 17 show the operating characteristics of the intake valve and exhaust valve in each area. It is a diagram. 5, 6 ... intake valve, 7 ... exhaust valve, 10 ... lift amount control device,
11 ... Cam, 13 ... Rocker arm, 15 ... Lever, 20 ... Lift control cam, 23 ... Control axis, 24 ... Torsion coil spring, 26
… Stepping motor, 37… Cam shaft, 37A… Torsional spline, 38… Timing pulley, 40… Phase control device, 41…
Hydraulic chamber, 44 ... Slider, 44A ... Torsional spline 49 ... Hydraulic control valve, 60 ... Control circuit, 61 ... Rotation speed sensor, 62 ... Throttle sensor

Claims (1)

[Claims] 1. A cylinder having at least two intake valves and one
In an internal combustion engine having two exhaust valves and a lift amount control device for increasing / decreasing the lift amount and open period of each of the two intake valves according to engine operating conditions, a camshaft for driving the intake valve and the exhaust valve Control the phase between the intake valve and the drive system to delay the opening phase of the intake valve and the exhaust valve at low and medium speed and low and medium load, and to control the opening phase of the intake valve and exhaust valve at high speed and high load. A valve control device for an internal combustion engine, comprising a phase control device for advancing.