JPH07229409A - Valve timing control device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a valve timing control device capable of suppressing the occurrence of deviation from the set value of the operation timing of an engine valve in a high rotation range. The phase difference of the intake valve camshaft 231 with respect to the crankshaft 213 is determined by the control device 26 from the output pulse of the first magnetic sensor 215 to the second magnetic sensor 236.
It is determined based on the time until the output pulse of. When the internal combustion engine rotational speed becomes higher than the threshold rotational speed, feedback control is stopped or the target phase difference is set to the maximum retardation value or less to mechanically operate the variable valve timing actuator (VVT) 233. The lower limit of the retard angle is fixed to suppress the decrease in the output due to the variation in the valve timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device for an internal combustion engine, and more particularly to a valve timing control device capable of preventing deviation of valve timing in a high speed range.

[0002]

2. Description of the Related Art A valve timing control device is known which can control the opening / closing timing of an engine valve according to the operating state of an internal combustion engine to increase the output or improve the fuel consumption. In order to accurately execute the valve timing control, it is necessary to measure the phase difference between the crankshaft and the camshaft that drives the engine valve. However, pulse signal generating means is provided for each of the crankshaft and the camshaft, and between the two pulses. Has been proposed (see Japanese Patent Application Laid-Open No. 59-105911).

Further, in an internal combustion engine equipped with a valve timing control device, it is common to set the opening timing of the intake valve to the retard side in order to increase intake efficiency and output in a high engine speed range. (Japanese Patent Laid-Open No. 60-27714)
See the bulletin).

[0004]

However, when the phase difference measuring method according to the above proposal is applied, the error in time measurement becomes large as the rotational speed of the internal combustion engine increases, and the retard amount does not match the set value. There is a risk. FIG. 1 is an explanatory view of a conventional phase difference measuring method, in which an upper part shows a crankshaft pulse and a lower part shows a camshaft pulse.

That is, assuming that the elapsed time tc from the fall of the crankshaft pulse to the fall of the next crankshaft pulse and the time t from the fall of the crankshaft pulse to the fall of the camshaft, the phase angle Δθ is Can be found at. Δθ = (t / tc) × 360 ° The rotation angle per unit time increases as the rotation speed increases, so the error in the phase difference increases as the rotation speed increases even if the error during time measurement is constant. .

Further, the vibration of the internal combustion engine becomes larger as the rotation speed becomes higher except the resonance point, so that the error in pulse detection becomes larger, and the error in the phase difference becomes larger as the rotation speed becomes higher. As the phase difference error increases, the deviation of the operation timing of the engine valve from the set value also increases, and the torque fluctuation and the output fluctuation also increase.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a valve timing control device capable of suppressing the occurrence of deviation from the set value of the operation timing of an engine valve in a high rotation range. To aim.

[0008]

A valve timing control device according to a first aspect of the present invention includes a rotational phase difference detecting means for detecting a rotational phase difference of a camshaft with respect to a crankshaft, and a target corresponding to an operating state of an internal combustion engine. A target rotational phase difference determining means for determining the rotational phase difference, and a camshaft for the crankshaft based on the target rotational phase difference determined by the target rotational phase difference determining means and the rotational phase difference detected by the rotational phase difference detecting means. Intake valve opening timing changing means for controlling the rotational phase difference of the intake valve and changing the opening timing of the intake valve, and changing the intake valve opening timing when the internal combustion engine rotational speed is equal to or higher than a predetermined threshold rotational speed. The most retarded rotational phase that stops the control of the rotational phase difference by the means and sets the rotational phase difference to the most retarded angle determined by the intake valve opening timing changing means With the setting means.

A valve timing control device according to a second aspect of the present invention determines a rotational phase difference detecting means for detecting a rotational phase difference of a camshaft with respect to a crankshaft, and a target rotational phase difference corresponding to an operating state of an internal combustion engine. Controlling the rotational phase difference of the camshaft with respect to the crankshaft based on the target rotational phase difference determining means, and the target rotational phase difference determined by the target rotational phase difference determining means and the rotational phase difference detected by the rotational phase difference detecting means. Intake valve opening timing changing means for changing the opening timing of the intake valve,
The target rotational phase difference determining means determines the target rotational phase from the most retarded angle value in the target rotational phase difference determined corresponding to the operating state when the internal combustion engine rotational speed is equal to or higher than a predetermined threshold rotational speed. Is also set to a value on the retard side.

[0010]

In the valve timing control device according to the first aspect of the invention, the valve timing feedback control is stopped when the rotational speed becomes equal to or higher than the threshold rotational speed,
The actuator is fixed to the mechanical retard lower limit value. First
In the valve timing control device according to the invention of
If the number of revolutions exceeds the threshold number of revolutions, the target phase difference of valve timing feedback control is set to a value on the retard side of the maximum retard value, and the actuator is fixed to the mechanical retard lower limit value. It

[0011]

2 is a block diagram of a valve timing control device according to the present invention, in which a cylinder 211 of an internal combustion engine 2 is provided with a piston 211 slidably up and down, and an upper portion of the piston 211 is provided with a combustion chamber 22. Has become. Piston 211
Is connected to the crankshaft 213 via the connecting rod 212.

A magnetic body 214 is attached to the crankshaft 213.
Is embedded and a reference pulse is output from the first magnetic sensor 215 arranged close to the crankshaft 213. A timing pulley 216 is installed at the tip of the crankshaft 213. An intake pipe 221 and an exhaust pipe 222 are connected to the combustion chamber 22,
A throttle valve 223 for adjusting the amount of intake air is installed upstream of the intake pipe 221. The opening of the throttle valve 223 is detected by the opening sensor 224.

An intake valve 23 is provided at a connection port between the combustion chamber 22 and the intake pipe 221, and a fuel injection valve 22 is provided immediately upstream of the intake valve 23.
5 is installed. An exhaust valve 24 is installed at the connection port between the combustion chamber 22 and the exhaust pipe 222. The intake valve 23 and the exhaust valve 24 are driven by cams (not shown) attached to the cam shafts 231 and 241.

Timing pulleys 232 and 242 are installed at the tips of the camshafts 231 and 241, and are driven via a timing pulley 216 and a timing belt 217 installed on the crankshaft. Further, a variable valve timing actuator (hereinafter referred to as VV) is provided between the intake valve cam shaft 231 and the timing pulley 232.
Write T. ) 233 is installed and the crankshaft 21
It is possible to change the rotation phase of the intake valve cam shaft 231 with respect to the No. 3 ratio.

The VVT 233 is supplied from a hydraulic pressure source (not shown).
The opening of the control valve 234 is driven by the supplied hydraulic pressure.
The rotation phase is controlled by controlling the
When the engine stops, the intake valve cam shaft 231 is driven by the spring force.
The rotation phase of the _LMechanical stop structure
Has become. In addition, the intake valve camshaft 231 is magnetic.
A second body 235, which has an embedded body and is placed in close proximity
Of the intake valve camshaft 231 from the magnetic sensor 236 of
A pulse is output for each rotation.

A distributor 25 is attached to the internal combustion engine 2 so that one pulse is generated by the first rotation speed sensor 251 every two rotations of the internal combustion engine, and the second rotation speed sensor 252 causes a 30 ° cam angle of the internal combustion engine. One pulse is output for each. The valve timing controller 26 is a microcomputer system, and the bus 26
1, the CPU 262, the memory 263, the input interface 264, and the output interface 265.
Composed of.

A first magnetic sensor 215, an opening sensor 224, a second magnetic sensor 236, a first rotation speed sensor 251, and a second rotation speed sensor 252 are connected to the input interface 264, and their respective detection signals are detected. Are taken into the valve timing controller 26. The output interface 265 includes a fuel injection valve 225 and a control valve 23.
4 are connected and controlled based on the calculation result of the valve timing control device 26.

FIG. 3 is a flow chart of a first valve timing control routine executed by the valve timing control device 26, which is executed every predetermined crank angle. In step 31, the internal combustion engine rotational speed Ne is read based on the output of the rotational speed sensor 252, and in step 32, it is determined whether the internal combustion engine rotational speed Ne is equal to or higher than a predetermined threshold rotational speed N _U (for example, 5000 rpm). judge.

When a negative determination is made, the routine proceeds to step 33, where the output pulse θc of the first magnetic sensor 214, the output pulse θi of the second magnetic sensor 236 and the opening TA of the throttle valve 223 detected by the throttle sensor 224.
Read. In step 34, based on the time tc between the output pulses θc of the two first magnetic sensors 214 and the time t between the output pulse θc of the first magnetic sensor 215 and the output pulse θi of the second magnetic sensor 236. Then, the phase difference Δθ of the camshaft 231 with respect to the crankshaft 212 is calculated.

That is, the above calculation can be expressed by the following equation. Δθ = f (θc, θi) In step 35, the target phase difference Dθ is determined from the internal combustion engine speed Ne and the opening degree TA of the throttle valve 223 based on the following equation. Dθ = g (Ne, TA) FIG. 4 is a map for determining the target phase difference Dθ, where the horizontal axis is the internal combustion engine speed Ne, the vertical axis is the throttle valve opening TA, and the parameter is the target phase difference. It is Dθ.

It should be noted that it is possible to use the intake air flow rate GN measured by an intake air flow rate sensor (not shown) instead of the throttle valve opening degree TA to determine the target phase difference Dθ. In step 36, the target phase difference Dθ and the phase difference Δθ
Then, the opening degree command signal α for the control valve 234 is determined. α = h (Dθ, Δθ) In step 37, the opening instruction signal α is output, the opening instruction signal α just output is stored as α _b , and this routine ends.

If a positive determination is made in step 32, that is, if it is appropriate to consider that the internal combustion engine rotation speed Ne is equal to or greater than the threshold rotation speed N _U and the calculation error of the phase difference Δθ is large, feedback is performed. In order to stop the control, the routine proceeds to step 38, the opening degree instruction signal α is set to zero, and the routine proceeds to step 37. As described above, when the control valve 234 is fully closed and the supply of hydraulic pressure is stopped, the VVT 233 is fixed to the mechanical retard angle lower limit position α _L.

Therefore, the feedback control of the phase difference is stopped, the valve timing is disturbed due to the error associated with the determination of the phase difference, and the output of the internal combustion engine is prevented from decreasing. According to the above-described valve timing control routine, when the internal combustion engine speed Ne suddenly changes, it is inevitable that the retard angle amount and the internal combustion engine torque suddenly change and an impact occurs.

FIG. 5 shows the addition of the function of suppressing the occurrence of impact.
Of the second valve timing control routine
Is also executed at every predetermined crank angle.
It In step 501, the internal combustion engine speed Ne is read,
In step 502, it is determined whether the flag XNE is "1".
judge. If a negative decision is made, proceed to step 503.
Only the rotation speed Ne is the threshold rotation speed N _UIs it above
To judge.

If an affirmative decision is made in step 503, the routine proceeds to step 504, where the flag XNE is set to "1". That is, the fact that the flag XNE is "1" means that the number of revolutions N
e is in a state of being equal to or higher than the threshold rotation speed N _U. Next, the routine proceeds to step 505, where feedback cancellation processing is executed.

If the affirmative judgment is made in step 502 and the negative judgment is made in step 503, step 5 is executed.
In 06, it is determined whether the rotation speed Ne is equal to or lower than the return rotation speed N _R. It should be noted that the return rotational speed N _R gives a hysteresis characteristic for preventing frequent repetition of suspension of feedback control due to fluctuations in the internal combustion engine rotational speed Ne, and is slightly smaller than the threshold rotational speed N _U. It is set to a value (for example, 4800 rpm).

When a negative determination is made in step 506, the process proceeds to step 505, and the feedback stopped state is continued. When the affirmative determination is made in step 506, step 50
7, the flag XNE is set to "0". That is, the fact that the flag XNE is "0" means that the rotation speed Ne is in the state of the return rotation speed N _R or less.

Next, in step 508, feedback control processing is executed. In step 509, it is determined whether or not the return flag XVVTL is "1". If a negative determination is made, it is determined that the return to the feedback control has not been completed, and the feedback return processing of step 510 is executed. If an affirmative decision is made in step 509, the return flag XVVTL is set to step 51 in step 511.
At 2, the stop flag XVVTH is reset.

Then, in step 513, the opening command signal α of the control valve 234 is output and this routine is ended. Figure 6
Is a detailed flowchart of the feedback cancellation process executed in step 505. In step 5051, it is determined whether or not the cancellation flag XVVTH is "1". If a negative determination is made, the process proceeds to step 5052.

In step 5052, the opening degree command signal α is decreased by a predetermined amount Δα to gradually close the control valve 234. In step 5053, it is determined whether or not the opening degree command signal α is less than or equal to zero, and if a positive determination is made, step 50
Proceed to 54. In step 5054, the opening command signal α is set to the lower limit value of zero, and in step 5055 the stop flag X is set.
VVTH is set to "1", and this processing ends.

If the affirmative decision is made in step 5053, or if the affirmative decision is made in step 5051, this process is ended directly. FIG. 7 is a detailed flowchart of the feedback control processing executed in step 508, which is the same as the processing from step 33 to step 36 of the first valve timing control routine.

That is, at step 5081, the output pulse θc of the first magnetic sensor 215, the output pulse θi of the second magnetic sensor 236 and the opening TA of the throttle valve 223 detected by the throttle sensor 224 are read. In step 5082, the time tc between the output pulses θc of the two first magnetic sensors 215 and the first magnetic sensor 21.
5 from the output pulse θc of the second magnetic sensor 236 to the crankshaft 2 based on the time t.
The phase difference Δθ of the camshaft 231 with reference to 12 is calculated.

In step 5083, the target phase difference Dθ is determined from the internal combustion engine speed Ne and the opening TA of the throttle valve 223 based on the following equation. Dθ = g (Ne, TA) In step 5084, the opening command signal α for the control valve 234 is determined from the target phase difference Dθ and the phase difference Δθ, and this process ends.

Α = h (Dθ, Δθ) FIG. 8 is a detailed flowchart of the feedback restoration process in step 510. In step 5101, the opening command signal α is equal to or _larger than the opening command signal α _b at the time of the previous execution. It is determined whether or not, and if an affirmative determination is made, the flow proceeds to step 5102, where α 1 = α _b + Δα is replaced, and this processing ends.

By this processing, the control valve 234 gradually opens from the fully closed state, and suppresses the occurrence of impact when shifting to the feedback control. When a negative determination is made in step 5101, it is considered that the return to the feedback is completed, the flag XVVTL is set to "1", and this processing is ended. FIG. 9 is a control explanatory diagram of the second valve timing control routine, in which the vertical axis represents the internal combustion engine speed Ne, the control valve opening α and the internal combustion engine torque, and the horizontal axis represents time.

That is, when the rotation speed Ne becomes equal to or higher than the threshold rotation speed N _{U at} time t ₁ , the control valve opening α is gradually closed at a constant speed and is fully closed at time t ₂ . When the rotation speed Ne becomes equal to or lower than the return rotation speed N _{R at} time t ₃ , the control valve opening α gradually opens at a constant speed and returns to the feedback control at time t ₄ . Therefore, the internal combustion engine torque also changes smoothly.

FIG. 10 is a flow chart of a third valve timing control routine executed by the valve timing control device according to the second aspect of the present invention. The first point is that the feedback control is continued even if the rotation speed Ne becomes high. Different from the first invention. Therefore, it differs from the first valve timing control routine in the following two points. Steps 32 and 38 are deleted from the first valve timing control routine, and constant feedback control is performed.

Further, in order to prevent the valve timing from becoming unstable when the rotation speed Ne becomes high, the target phase difference Dθ when the rotation speed Ne becomes high is set to be equal to or lower than the mechanical lower limit value. . Therefore, the setting of the function g (Ne, TA) that determines the target phase difference Dθ is different.

FIG. 11 is an example of a setting map of a function for determining the target phase difference Dθ, where (a) shows the setting in the first valve timing control routine and (b) shows the setting in the third valve timing control routine. Show settings. That is, when the rotation speed Ne is equal to or higher than the threshold rotation speed N _U (5000 rpm), the target phase difference Dθ is determined as a negative value.

The target phase difference Dθ is set to a value smaller than the setting in the first valve timing control routine as it approaches the threshold rotational speed N _U so that the target phase difference Dθ changes smoothly. FIG. 12 is a control explanatory diagram of the valve timing control device according to the second aspect of the present invention, in which the vertical axis indicates the target phase difference D.
θ and the torque of the internal combustion engine are represented by the rotation speed Ne on the horizontal axis.

That is, when the rotation speed Ne is high, the target phase difference Dθ is set to the retard side as shown by the solid line (a),
Since the actual phase difference Δθ fluctuates within the range indicated by the broken line, when the rotational speed Ne becomes N ₁ or more, the torque may decrease as indicated by the broken line (b). Therefore, the rotation speed Ne is N
_In the range of ₁ or more, the target phase difference Dθ is gradually decreased and fixed to a negative constant value at the threshold rotation speed N _U or more, and VVT
By setting 233 to the mechanical retardation lower limit position, variations in valve timing due to phase difference detection are eliminated and a decrease in torque is suppressed.

[0042]

According to the valve timing control device of the first aspect of the invention, the feedback control of the valve timing is stopped and the actuator is operated when the rotation speed becomes a high speed rotation above a predetermined threshold rotation speed. By fixing the retard angle lower limit value, it becomes possible to eliminate the variation in valve timing due to the detection of the phase difference and suppress the decrease in torque.

With the valve timing control device according to the second aspect of the present invention, the target phase difference of the feedback control of the valve timing is retarded to the maximum when the rotational speed becomes a high-speed rotation above a predetermined threshold rotational speed. By setting the value smaller than the value, the actuator can be fixed to the lower limit of the retard angle to eliminate the variation in valve timing due to the detection of the phase difference and suppress the decrease in torque.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a conventional phase difference measuring method.

FIG. 2 is a block diagram of a valve timing control device according to the present invention.

FIG. 3 is a flowchart of a first valve timing control routine.

FIG. 4 is a map for determining a target phase difference.

FIG. 5 is a flowchart of a second valve timing control routine.

FIG. 6 is a detailed flowchart of a feedback cancellation process.

FIG. 7 is a detailed flowchart of feedback control processing.

FIG. 8 is a detailed flowchart of a feedback return process.

FIG. 9 is a control explanatory diagram of a second valve timing control routine.

FIG. 10 is a flowchart of a third valve timing control routine.

FIG. 11 is an example of a setting table of a function that determines a target phase difference.

FIG. 12 is a control explanatory view of the valve timing control device according to the second invention.

[Explanation of symbols]

 2 ... Internal combustion engine 213 ... Crank shaft 215 ... First magnetic sensor 224 ... Throttle valve opening sensor 231 ... Cam shaft 233 ... VVT 234 ... Control valve 236 ... Second magnetic sensor 251 ... First rotational speed sensor 252 ... Second rotation speed sensor 26 ... Control device

Claims (2)

[Claims] 1. A rotational phase difference detecting means for detecting a rotational phase difference of a camshaft with respect to a crankshaft, a target rotational phase difference determining means for determining a target rotational phase difference corresponding to an operating state of an internal combustion engine, and the target. Based on the target rotational phase difference determined by the rotational phase difference determining means and the rotational phase difference detected by the rotational phase difference detecting means, the rotational phase difference of the camshaft with respect to the crankshaft is controlled to open the intake valve. A valve timing control device comprising: an intake valve opening timing changing means for changing the rotation position of the intake valve opening timing changing means when the internal combustion engine rotation speed is equal to or higher than a predetermined threshold rotation speed. The most retarded rotation position for stopping the control of the phase difference and setting the rotation phase difference to the most retarded angle determined by the intake valve opening timing changing means. A valve timing control device having a phase difference setting means. 2. A rotational phase difference detecting means for detecting a rotational phase difference of a camshaft with respect to a crankshaft, a target rotational phase difference determining means for determining a target rotational phase difference corresponding to an operating state of an internal combustion engine, and the target. Based on the target rotational phase difference determined by the rotational phase difference determining means and the rotational phase difference detected by the rotational phase difference detecting means, the rotational phase difference of the camshaft with respect to the crankshaft is controlled to open the intake valve. In a valve timing control device comprising: intake valve opening timing changing means for changing, the target rotation phase difference determining means determines the target rotation phase when the internal combustion engine rotation speed is equal to or higher than a predetermined threshold rotation speed. Is the valve timing that is set to a value on the retard side of the maximum retard value in the target rotational phase difference that is determined according to the operating state. Control device.