JPS62214207A - Tappet controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the interference between a piston and a valve by detecting the position of an angle adjusting member when the valve opening/closing time is controlled by varying the angle of a lever installed onto the back surface of a floating type rocker arm whose both edges are supported by a cam and a valve stem. CONSTITUTION:One edge of a rocker arm 13 is supported by a cam 11, and the other edge is supported by a valve stem 12, and the back surface is pressed by a lever 15, and then the rocker arm 13 is swung in floating. One edge of the lever 15 is supported by a pivot 19, and the other edge is supported by a lift control cam 20. The lift control cam 20 revolves in accordance with the operation state of an engine, and the valve opening/closing time and the lift quantity are controlled by adjusting the inclination angle of the lever 15. At this time, the revolution position of the cam 20 is detected, and the valve opening/closing time and the lift quantity are calculated, and the revolution position of the cam 20 is compared with the position of a piston, and the angle of the lever 15 is controlled so that the piston and the valve do not interfere each other.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a valve control device for an internal combustion engine that variably controls the lift characteristics of intake and exhaust valves according to engine operating conditions.

<Prior Art> Valve control devices for internal combustion engines that variably control the lift characteristics of intake and exhaust valves according to engine operating conditions are disclosed in, for example, Japanese Patent Laid-Open No. 60-26109 or Japanese Patent Laid-Open No. 60-2249.
As shown in Publication No. 09, there is a device in which the lift amount of the intake/exhaust valve is controlled by changing the fulcrum position of a rocker arm provided between the intake/exhaust valve and its driving cam. In this case, as the lift amount decreases, the opening timing is delayed and the closing timing is advanced, and the opening period becomes shorter.

Therefore, when this is applied to an intake valve, the lift amount and opening/closing timing of the intake valve are set to I+ in FIG. 11, for example.

It can be controlled like I2, and when the engine is at low speed and low load, it can be controlled like 12 (
By controlling the lift amount to decrease, the overlap with the exhaust valve can be reduced or reduced to O, and combustion can be improved by reducing residual gas, and gas flow can be strengthened (combustion improvement) by reducing the intake valve opening area. Riff) t? J&
Advantages such as reduction in valve train drive loss due to the reduction in the valve train drive loss can be obtained.

However, it is also true that the pump loss increases as the lift (2) decreases, canceling out the above advantages.

For this reason, as proposed by the present applicant in Japanese Patent Application No. 59-269429, a rotational phase control device is provided on the camshaft to control the rotational phase of the intake/exhaust valve drive cam according to engine operating conditions. , it is considered to be used in combination.

That is, at the same time as the lift control of the intake valve, the rotational phase of the intake valve and exhaust valve driving cams is controlled, and when the rev) ff1M is low, for example, 1 in FIG. , E, by advancing the rotational phase and reducing the effective intake stroke of the intake valve to suppress the intake air amount, the throttle by the engine throttle valve is reduced to control the load and reduce the intake negative pressure. This aims to reduce pump loss.

<Problems to be solved by the invention> However, when performing lift amount control and rotational phase control simultaneously in this way, a large lift amount is required when the engine accelerates, but when the rotational phase is on the leading side, riff 1-ff
If i was controlled to be large (IJ in FIG. 12), the opening timing of the intake valve would be extremely advanced, and there was a risk that the piston head and the valve head would interfere.

Furthermore, if interference is avoided in the design, problems such as the maximum lift amount and rotational phase control angle will be restricted, or a large recess will be required in the piston head, which will adversely affect combustion.

In view of these problems, it is an object of the present invention to make it possible to avoid the problem of interference with the piston when performing drift view control and rotational phase control at the same time.

Means for Solving the Problems> Therefore, as shown in FIG.
) and a lift amount control device (10) that controls the lift amount of the intake/exhaust valve (12) by changing the fulcrum position of the rocker arm (13) provided between the engine operating conditions. A valve control device for an internal combustion engine comprising a rotational phase control device (40) that controls a rotational phase of a driving cam (11), comprising rotational phase amount detection means (A) that detects a rotational phase amount of the cam (11). ) and a lift amount regulating means (B) for regulating the lift amount of the intake/exhaust valve (12) according to the detected rotational phase amount.

In the above configuration, the rotational phase amount is detected by the rotational phase amount detection means, and the lift amount is regulated by the lift amount regulating means based on this, so that interference with the piston can be avoided. The advantages of lift amount control and rotational phase control can be maximized.

<Example> An embodiment of the present invention will be described below.

The intake valve and exhaust valve are each driven by a cam attached to the same camshaft via a rocker arm, but the lift amount (and opening) of the intake valve is controlled by a lift amount control device as shown in Figures 2 to 4. period) is variable.

Referring to FIGS. 2 to 4, the lift amount control device 1° will be described. A rocker arm 13 is provided with both ends abutting a cam 11 and a stem end of an intake valve 12, and the rocker arm 13 is formed to curve. The rear surface 13a is brought into fulcrum contact with a lever 15 which is supported at one end so as to be swingable by a hydraulic pivot 19, which will be described later. Also, lever 1
5 is a shirt protruding from both side walls of the rocker arm 13) 1
3b is held in the concave groove 15a via the holding member 14, and between the spring seat 15b formed on the lever 15 and the holding member 14, there is a small spring constant that biases the rocker arm 13 downward. A spring 16 is interposed.

The hydraulic pivot 19 includes an outer cylinder 19a that is slidably inserted into a mounting hole 18a formed in a bracket 18 attached to the cylinder head, and an inner cylinder 19b that is fitted into the outer cylinder 19a. , and a check valve 19d is provided in a hydraulic chamber 19c formed between the two. and,
The intake valve 1 of the lever 15 is located at the hemispherical lower end of the outer cylinder 19a.
It fits into a concave portion 15c on the upper surface of one end on the second stem end side, and supports the lever 15 in a freely swinging manner. Then, hydraulic pressure is supplied from a hydraulic pressure supply passage 18b formed inside the valve 18 to the hydraulic chamber 19c through the inside of the inner cylinder 19b and the check valve 19d to keep the valve clearance constant.

Further, a lift control cam 20 rotatably attached to the bracket 18 as described later is attached to the cam l of the lever 15.
The lever 15 is engaged with the upper surface of the other end on the l side to regulate the swinging 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 of different heights so as to change the lift amount of the intake valve 12 in stages, and has a control shaft 23 (described later) in the center. It has a hole 20g through which it is inserted. Further, the cylindrical portion 20h formed to protrude from both ends of the lift control cam 20 is fastened to the lower arcuate groove 18C formed in the bracket 18 with bolts 21 on the bracket 18, as shown in FIGS. 3 and 4. A pair of caps 2
It is held freely rotatably between the upper arcuate groove 22a formed in the upper circular groove 22a.

Then, one control shaft 23 is inserted into the hole 20g formed by penetrating the center of the lift control cam 20 provided in several cylinders in a loose fit state, and the control shaft 23 is inserted into both side portions of each lift control cam 20. A set screw 2 screws one end of each fitted torsion coil spring 24 into the outer peripheral surface of the control shaft 23.
3a, and the other end of the coil spring 24 is fitted into a hole 20i formed in the end surface of the cylindrical portion 20h of the lift control cam 20 to be locked therein.

One end of the control shaft 23 is connected via a joint 25 to a drive shaft 26a of a stellar pin 2 motor 26. The stamping motor 26 is driven by a control circuit 27 based on engine operating conditions such as the engine rotational speed N and throttle valve opening α, and rotates the control shaft 23 to a predetermined rotation position. .

29 is a valve spring.

Therefore, when the lift control cam 20 is in contact with the lever 15 with the cam surface 20a having the largest lift amount,
The lever 15 is pushed down to the cam 11 side the most. For this reason, the lower surface of the lever 15, which is in fulcrum contact with the back surface 13a of the rocker arm 13, also lowers, and the fulcrum contact point A moves toward the cam 11 while being transmitted to the intake valve 12.
is large, and the opening time is early and the closing time is late.

On the other hand, when the lift control cam 20 is rotated so that, for example, the cam surface 20e with the smallest lift amount comes into contact with the lever 15, the end of the lever 15 on the cam 11 side becomes a concave portion 15c.
The lower surface of the lever 15 also retreats upward by swinging with the lever 15 as a fulcrum.

The rocker arm 13 on the lower surface of the lever 15 serves as a fulcrum for transmitting the lift of the cam 11 to the intake valve 12.
is in contact with the rocker arm 13 at the base circle, and the initial position of the fulcrum is at the cam surface 20a with the large lift amount.
The right side in Fig. 2 compared to when the lever 15 is in contact with the
That is, after the lift, the fulcrum moves away from the direction in which it moves. As a result, the lift amount is small, and the opening timing is late and the closing timing is early.

In this manner, by rotating the lift control cam 20 and bringing any of the cam surfaces 20a to 20e into contact with the lever 15, the lift amount characteristics of the intake valve 12 can be changed in stages.

Here, the lift control cam 20 is rotated via a control shaft 23 and a torsion coil spring 24 by driving a stamping motor 26 .

Now, at the timing when the control shaft 23 rotates, in the cylinder where the intake valve 12 is being lifted, the contact fulcrum between the rocker arm 13 and the lever 15 is moving toward the cam 11, and a large reaction force of the valve spring 29 is generated. is the rocker arm 13.
It acts on the lift control cam 20 via the lever 15. For this reason, the lift control cam 20 remains fixed and twists the torsion coil springs 24 on both sides of the lift control cam 20 while twisting the control shaft 24.
Only 3 rotates. Next, after the cam 11 rotates and the intake valve 12 closes, the contact fulcrum between the rocker arm 13 and the lever 15 is positioned approximately above the intake valve 12, and the reaction force of the valve spring 29 disappears. Therefore, the only force acting on the lift control cam 20 is the weak force of the spring 16 attached between the rocker arm 13 and the lever 15. Therefore, the torque stored in the recoil spring 24 during the lift of the intake valve 12 can overcome the weak force of the spring 16 and rotate the lift control cam 20.

Next, a rotational phase control device 40 for controlling the rotational phase of the intake valve and exhaust valve driving cams will be explained with reference to FIGS. 5 and 6.

That is, as shown in FIG. 5, in addition to the intake valve driving cam 11,
A timing pulley 38 is connected to one end of a camshaft 37 forming an exhaust valve driving cam (not shown), and this timing pulley 38 is interlocked with an engine crankshaft (not shown) via a toothed timing belt 39. . And a connecting part (fixed part) between the timing pulley 38 and the camshaft 37
A rotational phase control device 4 that controls the rotational phase of the cam 11, etc.
0 is included.

The rotational phase control device 40 includes an annular piston 42 that freely slides and reciprocates within an annular cylinder 38A formed within a timing block 113 to define a hydraulic chamber 41 within the cylinder 38A; 42 and slides along the camshaft 37 against the biasing force of the coil spring 43 due to the reciprocating motion of the piston 42, and the camshaft 37 whose movement is restricted via the coil spring 43. It has a stopper member 45 fixed to the end face with a bolt 50. As shown in FIG. 6, the slider 44 has a torsion spline 44A formed on the inner surface of its hollow part, and has a flange 44B at one end on which the piston 42 comes into contact, and a cylinder 38A at the other end. A protrusion 44C is formed to be slidably supported in a groove 38B formed in the inner wall.

Further, as shown in FIG. 6, a torsion spline 37A is formed at one end of the camshaft 37, and this torsion spline 37A meshes with a torsion spline 44A of the slider 44.

46 in Fig. 5 indicates the inside of the camshaft 37 and the timing pulley 3.
One end of this hydraulic passage 46 communicates with the hydraulic chamber 41, and the other end communicates with an external hydraulic pressure supply passage 47. This hydraulic supply passage 4
The other end of 7 branches into two in the middle, one passage 47A is connected to an oil pump 48, and the other passage 47B is connected to a hydraulic control valve 49.
are connected to each other. This hydraulic control valve 49 is of an electromagnetic type and controls the hydraulic pressure supplied from the oil pump 48 to the hydraulic chamber 41 in accordance with an electric signal.

Therefore, the hydraulic pressure to the hydraulic chamber 41 is controlled by the hydraulic control valve 49, and the slider 44 is positioned in the axial direction according to this hydraulic pressure. Then, the torsion spline 37A corresponds to the position of the slider 44.

When 44A slides in the axial direction, the camshaft 37 rotates by a predetermined amount, thereby controlling the rotational phase of the cam 11 and the like.

Note that the hydraulic control valve 49 is controlled by the control circuit 52 based on engine operating conditions such as the engine speed N and the throttle valve opening degree α.

As shown in FIG. 5, the configuration according to the present invention is such that the iron bar piece 61 is fixed to the belt cover 55 so as to move relative to the end face of the slider 44 as the slider 44 moves. A position sensor 60 is provided. Of course, this position sensor 60 is provided with a cylindrical coil inside.

The signal from the position sensor 60 is then input to the control circuit 27 of the lift amount control device 10 as shown in FIG.

In this control circuit 27, the operation of the stepping motor 26 is controlled according to the flowchart shown in FIG.

To explain the flowchart in Fig. 7, in step 1 (indicated by Sl in the figure, the same applies hereinafter), engine operating conditions such as engine speed N and throttle valve opening α are detected, and in step 2, engine operating conditions such as engine speed N and throttle valve opening α are detected. The optimum lift amount is set by searching based on the engine operating conditions.

Next, in step 3, the amount of rotational phase is read based on the signal from the position sensor 60, and in step 4, the maximum allowable lift i is set by searching based on the amount of rotational phase read.

Next, in step 5, the set lift i is compared with the allowable maximum lift amount, and if the set lift amount exceeds the allowable maximum lift (ffl), the process proceeds to step 6, where the set lift amount is changed to the allowable maximum lift amount. This part of step 5.6 is not clear)! It corresponds to a regulatory measure.

After that, in step 7, the stepping motor 26 is operated to select the cam surfaces 20a to 20e corresponding to the set lift amount.
to drive.

As a result, at low speeds and low loads, by reducing the lift amount of the intake valve and advancing the rotational phase of the intake valve and exhaust valve driving cams, as shown in Figure 8, the pump loss is reduced and combustion is improved. etc.

Furthermore, during acceleration, as shown in FIG. 9, the lift amount of the intake valve is increased to improve the filling efficiency. At this time,
If the amount of lift is increased when the amount of rotational phase of the cam is controlled to be large, the opening timing of the intake valve will advance greatly, making it easier to interfere with the piston. Then, the lift amount is changed from (a) to (b) in Fig. 9 to avoid interference with the piston.

Incidentally, FIG. 10 shows the lift characteristics at high speed and high load.

<Effects of the Invention> As explained above, according to the present invention, the amount of rotational phase is detected and the amount of lift is regulated to avoid interference with the piston, so the maximum lift amount and rotational phase control angle are set small in advance. Also, there is no need to form a large recess in the piston head, and the advantages of lift amount control and rotational phase control can be maximized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a sectional view showing an embodiment of the lift amount control device, FIG. 3 is a plan view of FIG. 2, and FIG. FIG. 5 is a sectional view showing an embodiment of the rotational phase control device; FIG. 6 is an exploded perspective view of the slider and cam shaft end in FIG. 5; FIG. 7 is a perspective view of the lift control cam part; A flowchart showing the control contents of the control circuit in FIG. 3, FIGS. 8 to 10 are lift characteristic diagrams in the same embodiment, and FIGS. 11 and 12 are lift characteristic diagrams in the conventional example. 10... Lift amount control device 11... Cam 1
2...Intake valve 13...Rocker arm 15...
Lever 20... Lift control cam 23... Control shaft 24... Torsion coil spring 26...
・Stepping motor 27...control circuit 37...
・Cam shaft 37A...Tear spline 38...
・Timing pulley 40...Rotation phase control device
41... Hydraulic chamber 44... Slider 44A...
・Torsion spline 49... Hydraulic control valve 52...
Control circuit 60...Position sensor patent applicant Nissan Motor Co., Ltd. agent Patent attorney Fujio SasashimaFigure 2Figure 6Figure 7

Claims (1)

[Claims] A lift amount control device that controls the lift amount of the intake/exhaust valve by changing the fulcrum position of a rocker arm provided between the intake/exhaust valve and its driving cam according to the engine operating conditions, and a rotational phase control device for controlling the rotational phase of an intake/exhaust valve driving cam; a rotational phase amount detection means for detecting the rotational phase amount of the cam; Suction and absorption depending on the amount of phase.
1. A valve control device for an internal combustion engine, comprising: lift amount regulating means for regulating the lift amount of an exhaust valve.