JP4056312B2 - Valve timing control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve timing control device for an internal combustion engine that can change the opening / closing timing of an exhaust valve in accordance with the operating state of the internal combustion engine.
[0002]
[Prior art]
Conventionally, as a prior art document relating to a valve timing control device for an internal combustion engine, one disclosed in Japanese Patent Laid-Open No. 5-118232 is known. In this system, reduction of fuel consumption (improvement of fuel consumption) and NOx (nitrogen oxide) are performed without performing exhaust gas recirculation (exhaust gas recirculation) control from the outside to the internal combustion engine. ) Shows a technology for achieving both reductions in
[0003]
[Problems to be solved by the invention]
By the way, in the above-mentioned, the target residual exhaust gas amount, that is, the internal EGR amount necessary for reducing NOx in the entire load range is secured by combining the opening / closing timings of the intake valve and exhaust valve of the internal combustion engine. However, it is said that fuel consumption can be reduced above the middle load range. Here, in the above-mentioned thing, in the low load region of the internal combustion engine, combustion deterioration due to an increase in the internal EGR amount is caused, so that not only the fuel consumption cannot be reduced but also the possibility of worsening the emission is assumed. .
[0004]
Therefore, the present invention has been made to eliminate the predictability of such a problem, and is a valve timing control device for an internal combustion engine that can reduce fuel consumption without causing deterioration of combustion in a low load region of the internal combustion engine. Offering is an issue.
[0005]
[Means for Solving the Problems]
According to the valve timing control device for an internal combustion engine of claim 1, the crank angle immediately before the pressure in the combustion chamber drops and becomes negative in the combustion stroke of the internal combustion engine by the crank angle calculation means is set based on various operating parameters. The variable valve timing control mechanism is controlled by the valve timing control means so that the crank angle calculated as the crank angle and the crank angle of the exhaust valve opening timing detected by the crank angle detection means coincides with the target crank angle. As a result, the pressure in the combustion chamber in the low load region of the internal combustion engine is prevented from becoming a negative pressure, so that the pumping loss as an exhaust loss can be eliminated and the combustion in the low load region of the internal combustion engine is deteriorated. Without incurring fuel consumption.
[0006]
According to the valve timing control apparatus for an internal combustion engine of claim 2, the pressure in the combustion chamber drops during the combustion stroke of the internal combustion engine by the crank angle calculation means and once becomes negative pressure, then in the combustion stroke in the subsequent exhaust stroke. The crank angle at which the pressure recovers to near atmospheric pressure is calculated as the target crank angle based on various operating parameters, and the crank angle at the opening timing of the exhaust valve detected by the crank angle detecting means matches the target crank angle. The variable valve timing control mechanism is controlled by the valve timing control means. As a result, the exhaust valve is prevented from opening when the pressure in the combustion chamber in the low load region of the internal combustion engine is negative, so that a pumping loss as an exhaust loss can be eliminated. The fuel consumption is reduced without causing deterioration of combustion in the low load region of the internal combustion engine.
[0007]
In the valve timing control device for an internal combustion engine according to claim 3, the various operating parameters are set to at least one of the load of the internal combustion engine based on the intake air amount, the intake pressure, or the load and the engine rotational speed. Without directly detecting the pressure in the combustion chamber, it is possible to obtain an effect that the transition state can be appropriately understood by various operation parameters.
[0008]
According to the valve timing control apparatus for an internal combustion engine of claim 4, the point in time when the pressure in the combustion chamber drops and becomes negative in the combustion stroke of the internal combustion engine is detected by the combustion chamber pressure detection means, and this negative pressure is reached. The variable valve timing control mechanism is controlled by the valve timing control means so that the opening timing of the exhaust valve detected by the crank angle detection means coincides with the time point. As a result, the pressure in the combustion chamber in the low load region of the internal combustion engine is prevented from becoming a negative pressure, so that the pumping loss as an exhaust loss can be eliminated and the combustion in the low load region of the internal combustion engine is deteriorated. Without incurring fuel consumption.
[0009]
According to the valve timing control device for an internal combustion engine of claim 5, the pressure in the combustion chamber drops in the combustion stroke of the internal combustion engine by the combustion chamber pressure detection means, and once becomes negative pressure, then in the combustion stroke in the subsequent exhaust stroke. Is detected, and the variable valve timing control mechanism is controlled so that the opening timing of the exhaust valve detected by the crank angle detecting means coincides with the time when the pressure recovers to near atmospheric pressure. As a result, the exhaust valve is prevented from opening when the pressure in the combustion chamber in the low load region of the internal combustion engine is negative, so that a pumping loss as an exhaust loss can be eliminated. The fuel consumption is reduced without causing deterioration of combustion in the low load region of the internal combustion engine.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0011]
<Example 1>
FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a valve timing control device for an internal combustion engine according to a first example of an embodiment of the present invention is applied and its peripheral devices.
[0012]
In FIG. 1, an intake passage 11 is connected to an internal combustion engine 10, and an air cleaner 12 for purifying intake air from the upstream side, an air flow meter 13 for detecting an intake amount (intake air amount) QA, and the intake passage 11 A throttle valve 14 for controlling the amount QA, an intake air temperature sensor 16 for detecting the intake air temperature THA through a surge tank 15 for preventing intake air pulsation, and an injector (fuel injection valve) 18 for injecting and supplying fuel to the intake port 17 It is arranged. The air-fuel mixture of the air from the intake passage 11 and the fuel from the injector 18 is a combustion chamber formed by the cylinder block 20 and the piston 21 of the internal combustion engine 10 in accordance with the opening / closing timing of the intake valve 19 from the intake port 17. 22 is introduced. The air-fuel mixture introduced into the combustion chamber 22 is combusted by spark ignition of the spark plug 23 and then discharged to the exhaust passage 26 through the exhaust port 25 according to the opening / closing timing of the exhaust valve 24.
[0013]
Here, a known variable valve timing control mechanism 30 using an electromagnetic actuator 31 whose opening / closing timing can be freely changed is connected to the exhaust valve 24 of the present embodiment. The variable valve timing control mechanism 30 is provided with a valve lift sensor 32 that detects the valve lift amount VL of the exhaust valve 24. Further, the internal combustion engine 10 is provided with a crank angle sensor 28 that detects a crank angle CA that is a rotation angle of the crankshaft 27.
[0014]
The intake air amount QA from the air flow meter 13, the intake air temperature THA from the intake air temperature sensor 16, the valve lift amount VL from the valve lift sensor 32, the crank angle CA from the crank angle sensor 28, etc. are ECU (Electronic Control Unit: electronic control). Unit) 40. The ECU 40 is a CPU as a central processing unit that executes various known arithmetic processes, a ROM that stores control programs and control maps, a RAM that stores various data, a B / U (backup) RAM, an input / output circuit, and those Is configured as a logical operation circuit including a bus line or the like for connecting the two. The ECU 40 outputs control signals such as a fuel injection amount TAU for the injector 18, an ignition timing Ig for the spark plug 23, and a valve drive signal VD for the exhaust valve 24 for the electromagnetic actuator 31.
[0015]
Next, the behavior of the pressure P in the combustion chamber 22 corresponding to the open periods of the intake valve 19 and the exhaust valve 24 of the internal combustion engine 10 according to the present embodiment will be described with reference to FIGS. 2, 3, and 4. . 2 is a characteristic diagram showing the behavior of the pressure P in the combustion chamber 22 in the low load region of the internal combustion engine 10, and FIG. 3 is an enlarged detail view of a part A in FIG. FIG. 4 is a characteristic diagram showing the behavior of the pressure P in the combustion chamber 22 in the middle and high load range of the internal combustion engine 10 for comparison.
[0016]
As shown in FIG. 4, in the middle and high load range of the internal combustion engine 10, the pressure P in the combustion chamber 22 with respect to the crank angle [° CA (Crank Angle)] that is the rotation angle of the crankshaft 27 of the internal combustion engine 10 is The behavior is as shown by the thick solid line. That is, in the middle and high load range of the internal combustion engine 10, the combustion stroke and the exhaust stroke after the TDC (Top Dead Center) among the continuous intake stroke → compression stroke → combustion stroke → exhaust stroke of the internal combustion engine 10 are performed. The pressure P in the combustion chamber 22 is lower than the atmospheric pressure and does not become negative pressure.
[0017]
In contrast, as shown in FIGS. 2 and 3, in the low load region of the internal combustion engine 10, the inside of the combustion chamber 22 with respect to the crank angle [° CA] that is the rotation angle of the crankshaft 27 of the internal combustion engine 10. The pressure P becomes a behavior as shown by a thick solid line. That is, in the low load region of the internal combustion engine 10, the pressure P in the combustion chamber 22 is higher than the atmospheric pressure in the combustion stroke after the TDC among the continuous intake stroke → compression stroke → combustion stroke → exhaust stroke of the internal combustion engine 10. There is a negative pressure period that goes down. During this negative pressure period, the exhaust valve 24 is in the open state during the open period under normal control, so that a pumping loss occurs as an exhaust loss that occurs when the burned gas is discharged to the outside. This is a factor that causes deterioration in fuel consumption.
[0018]
Therefore, in this embodiment, the main point is to eliminate the pumping loss as the exhaust loss in the low load region of the internal combustion engine 10, and the variable valve timing control mechanism 30 is used to set the opening timing (valve opening timing) in the opening period of the exhaust valve 24. Used, the behavior of the pressure P in the combustion chamber 22 by the normal control as shown by a thick solid line in FIG. 3 is changed by the advance angle control or the retard angle control. That is, the “STD” position, which is the opening timing in the opening period of the exhaust valve 24 by the normal control, is shown immediately before the pressure P in the combustion chamber 22 becomes negative by the advance angle control, as shown by a thick broken line in FIG. To “S (advance)” position, or as indicated by a thick dashed line in FIG. 3, the pressure P in the combustion chamber 22 is once reduced to negative pressure by the retard angle control, and is near atmospheric pressure. Is delayed to the “T (retard)” position.
[0019]
First, based on the flowchart of FIG. 5 showing the processing procedure of the advance angle control by the variable valve timing control mechanism 30 in the ECU 40 used in the valve timing control device for an internal combustion engine according to the first example of the embodiment of the present invention. This will be described with reference to FIGS. 3 and 4 described above. This advance angle control routine is repeatedly executed by the ECU 40 every predetermined time.
[0020]
In FIG. 5, first, in step S101, the intake air amount QA [g / sec] from the air flow meter 13 is read. Next, the routine proceeds to step S102, where the intake air temperature THA [° C.] from the intake air temperature sensor 16 is read. Next, the process proceeds to step S103, and the engine speed NE [rpm] based on the crank angle CA from the crank angle sensor 28 is read. Next, the process proceeds to step S104, and the fuel injection amount TAU corresponding to the operation state at this time is calculated. Next, the process proceeds to step S105, and the ignition timing Ig corresponding to the operation state at this time is calculated.
[0021]
Next, in step S106, the pressure P in the combustion chamber 22 during the combustion stroke of the internal combustion engine 10 is calculated based on the intake air amount QA, the intake air temperature THA, the fuel injection amount TAU, and the ignition timing Ig as various operation parameters. At the same time, the pressure P in the combustion chamber 22 decreases during the combustion stroke of the internal combustion engine 10, and the crank angle immediately before becoming negative pressure, that is, when equal to the atmospheric pressure is calculated as the target crank angle TGCA. Next, the process proceeds to step S107, and it is determined whether the pressure in the combustion chamber 22 becomes negative during the combustion stroke of the internal combustion engine 10. If the determination condition of step S107 is not satisfied, that is, the pressure P in the combustion chamber 22 does not become negative during the combustion stroke of the internal combustion engine 10, that is, if the operating state of the internal combustion engine 10 is in the middle and high load range. The routine proceeds to S108 where control is performed so that the crank angle CA, which is the opening timing of the exhaust valve 24 during the opening period of the normal control, becomes the “STD” position shown in FIG. finish.
[0022]
On the other hand, when the determination condition of step S107 is satisfied, that is, when the operating state of the internal combustion engine 10 is in the low load region such that the pressure P in the combustion chamber 22 becomes negative during the combustion stroke of the internal combustion engine 10, the process proceeds to step S109. Then, the valve drive signal VD is output so that the opening timing of the exhaust valve 24 becomes the target crank angle TGCA calculated in step S106. Next, the process proceeds to step S110, and the current valve lift amount VL of the exhaust valve 24 by the valve lift sensor 32 is read. The valve lift amount VL from the valve lift sensor 32 is used to determine the opening / closing timing of the exhaust valve 24 and abnormality of the valve lift amount VL.
[0023]
Next, the process proceeds to step S111, and the current crank angle CA from the crank angle sensor 28 is read. Next, the routine proceeds to step S112, where it is determined whether the exhaust valve 24 has reached the open timing at the target crank angle TGCA. When the determination condition in step S112 is satisfied, that is, when the target crank angle TGCA calculated in step S106 matches the current crank angle CA read in step S111, the exhaust valve 24 is opened at a suitable opening timing. The routine ends without changing the valve drive signal VD.
[0024]
On the other hand, if the determination condition in step S112 is not satisfied, that is, if the target crank angle TGCA calculated in step S106 does not match the current crank angle CA read in step S111, the process proceeds to step S113, and the target crank angle It is determined whether the current crank angle CA, which is the opening timing of the exhaust valve 24, is earlier than the TGCA. When the determination condition in step S113 is satisfied, that is, when the current crank angle CA, which is the opening timing of the exhaust valve 24, is earlier than the target crank angle TGCA, the process proceeds to step S114, and the valve drive signal VD is set to the retard side. Only the crank angle is changed, and this routine ends.
[0025]
On the other hand, when the determination condition of step S113 is not satisfied, that is, when the current crank angle CA, which is the opening timing of the exhaust valve 24, is later than the target crank angle TGCA, the routine proceeds to step S115, and the valve drive signal VD advances. The predetermined crank angle is changed to the corner side, and this routine is finished. Through the above-described advance angle control routine, the crank angle CA, which is the opening timing of the exhaust valve 24 during the opening period, is matched with the “S” position shown in FIG. 3, that is, the target crank angle TGCA.
[0026]
As described above, the valve timing control device for the internal combustion engine of the present embodiment is based on the variable valve timing control mechanism 30 that can change the opening / closing timing of the exhaust valve 24 of the internal combustion engine 10 and the rotation angle of the crankshaft 27 of the internal combustion engine 10. A crank angle sensor 28 serving as a crank angle detecting means for detecting a certain crank angle CA, and the crank angle immediately before the pressure P in the combustion chamber 22 drops and becomes negative pressure during the combustion stroke of the internal combustion engine 10 are used as various operating parameters. The crank angle calculating means achieved by the ECU 40 that calculates the target crank angle TGCA based on the target crank angle CA, and the crank angle CA of the opening timing of the exhaust valve 24 detected by the crank angle sensor 28 is calculated by the crank angle calculating means. Achieved by the ECU 40 that controls the variable valve timing control mechanism 30 to match the angle TGCA It is those comprising a valve timing control means. Further, the valve timing control apparatus for an internal combustion engine according to the present embodiment uses various operating parameters as the load of the internal combustion engine 10 and the engine speed NE based on the intake air amount QA.
[0027]
That is, the pressure P in the combustion chamber 22 decreases during the combustion stroke of the internal combustion engine 10 and the crank angle immediately before becoming negative pressure is set as the target crank angle TGCA, and the load of the internal combustion engine 10 based on the intake air amount QA and the engine speed NE. The variable valve timing control mechanism 30 is controlled so that the crank angle CA at the opening timing of the exhaust valve 24 coincides with the target crank angle TGCA. As a result, the pressure P in the combustion chamber 22 in the low load region of the internal combustion engine 10 does not become a negative pressure, and the pumping loss as an exhaust loss can be eliminated. Therefore, the combustion deterioration in the low load region of the internal combustion engine The fuel consumption can be reduced without incurring.
[0028]
Next, FIG. 6 is a flowchart showing the processing procedure of the retard control by the variable valve timing control mechanism 30 in the ECU 40 used in the valve timing control device for an internal combustion engine according to the first example of the embodiment of the invention. This will be described with reference to FIG. This retard angle control routine is repeatedly executed by the ECU 40 every predetermined time.
[0029]
In FIG. 6, Step S201 to Step S205, Step S207, Step S208, Step S210 to Step S215 correspond to Step S101 to Step S105, Step S107, Step S108, Step S110 to Step S115 in the above-described embodiment. Therefore, detailed description thereof is omitted.
[0030]
In step S206, the pressure P in the combustion chamber 22 during the combustion stroke of the internal combustion engine 10 is calculated based on the intake air amount QA, the intake air temperature THA, the fuel injection amount TAU, and the ignition timing Ig as various operating parameters. In the combustion stroke of the engine 10, the pressure P in the combustion chamber 22 drops and once becomes negative, and then the crank angle when the pressure P in the combustion chamber 22 recovers to near atmospheric pressure in the subsequent exhaust stroke is the target crank angle. Calculated as the angle TGCA. Next, the process proceeds to step S209, and the valve drive signal VD is output so that the opening timing of the exhaust valve 24 becomes the target crank angle TGCA calculated in step S206. Through the above-described retard control routine, the crank angle CA, which is the opening timing of the exhaust valve 24 during the opening period, is matched with the “T” position shown in FIG. 3, that is, the target crank angle TGCA.
[0031]
As described above, the valve timing control device for the internal combustion engine of the present embodiment is based on the variable valve timing control mechanism 30 that can change the opening / closing timing of the exhaust valve 24 of the internal combustion engine 10 and the rotation angle of the crankshaft 27 of the internal combustion engine 10. Crank angle sensor 28 serving as a crank angle detection means for detecting a certain crank angle CA, and the pressure P in the combustion chamber 22 drops during the combustion stroke of the internal combustion engine 10 and once becomes negative pressure, then burns in the subsequent exhaust stroke. The crank angle calculation means achieved by the ECU 40 that calculates the crank angle when the pressure P in the chamber 22 recovers to near atmospheric pressure as the target crank angle TGCA based on various operating parameters, and the crank angle sensor 28 detect the crank angle. The crank angle CA at the opening timing of the exhaust valve 24 is equal to the target crank angle TGCA calculated by the crank angle calculating means. Those comprising a valve timing control means is achieved by ECU40 for controlling the variable valve timing control mechanism 30 so as to. Further, the valve timing control apparatus for an internal combustion engine according to the present embodiment uses various operating parameters as the load of the internal combustion engine 10 and the engine speed NE based on the intake air amount QA.
[0032]
That is, after the pressure P in the combustion chamber 22 drops during the combustion stroke of the internal combustion engine 10 and once becomes negative, the crank angle when the pressure P in the combustion chamber 22 recovers to near atmospheric pressure in the subsequent exhaust stroke. Is calculated as the target crank angle TGCA based on the load of the internal combustion engine 10 and the engine speed NE based on the intake air amount QA, and variable valve timing control is performed so that the crank angle CA of the opening timing of the exhaust valve 24 coincides with the target crank angle TGCA. The mechanism 30 is controlled. As a result, the exhaust valve 24 is not opened during the period in which the pressure P in the combustion chamber 22 in the low load region of the internal combustion engine 10 is negative, and the pumping loss as an exhaust loss can be eliminated. The fuel consumption can be reduced without causing deterioration of combustion in the low load region of the internal combustion engine.
[0033]
<Example 2>
FIG. 7 is a schematic configuration diagram showing an internal combustion engine to which the valve timing control device for an internal combustion engine according to a second example of the embodiment of the present invention is applied and its peripheral devices. In the figure, components having the same configuration or corresponding parts as those in the first embodiment are given the same reference numerals and symbols, and only the differences will be described.
[0034]
In this embodiment, as shown in FIG. 7, an in-cylinder pressure sensor 29 is disposed on the side wall of the cylinder block 20 of the internal combustion engine 10 so as to face the combustion chamber 22. On the other hand, as shown in FIG. 1 of the first embodiment described above. The air flow meter 13 and the intake air temperature sensor 16 are removed from the intake passage 11. That is, in the present embodiment, the pressure P in the combustion chamber 22 can be directly detected by the in-cylinder pressure sensor 29, and therefore the pressure P in the combustion chamber 22 is determined based on the intake air amount QA from the air flow meter 13 and the intake air temperature sensor. Therefore, it is not necessary to calculate from the operation parameters such as the intake air temperature THA from 16.
[0035]
Next, FIG. 8 is a flowchart showing a processing procedure of the advance angle control by the variable valve timing control mechanism 30 in the ECU 40 used in the valve timing control apparatus for an internal combustion engine according to the second example of the embodiment of the invention. This will be described with reference to FIG. This advance angle control routine is repeatedly executed by the ECU 40 every predetermined time.
[0036]
In FIG. 8, first, in step S301, the current crank angle CA from the crank angle sensor 28 is read. Next, the routine proceeds to step S302, where the crank angle CA read in step S301 is the opening timing in the opening period of the exhaust valve 24 by the normal control of the exhaust valve 24, the "STD" position shown in FIG. It is determined whether it is before. When the determination condition in step S302 is not satisfied, that is, when the exhaust valve 24 is later than the opening timing by the normal control, the process proceeds to step S303, the exhaust valve 24 is opened, and this routine is finished.
[0037]
On the other hand, when the determination condition of step S302 is satisfied, that is, before the opening timing by the normal control of the exhaust valve 24, the routine proceeds to step S304, where the in-cylinder pressure (pressure in the combustion chamber 22) P from the in-cylinder pressure sensor 29 is reached. Is read. Next, the process proceeds to step S305, where it is determined whether the in-cylinder pressure P read in step S304 is equal to or lower than a reference pressure Pth (see FIG. 3). Here, the reference pressure Pth is set in consideration of a response delay of the variable valve timing control mechanism 30 and the like. When the determination condition of step S305 is not satisfied, that is, when the in-cylinder pressure P exceeds the reference pressure Pth and is still large, the process returns to step S301 and the same processing is repeatedly executed.
[0038]
On the other hand, when the determination condition of step S305 is satisfied, that is, when the in-cylinder pressure P becomes smaller than the reference pressure Pth, the routine proceeds to step S306, where the valve drive signal VD is output to open the exhaust valve 24, and this routine is performed. Exit. By the above-described advance angle control routine, the crank angle CA, which is the opening timing of the exhaust valve 24 during the opening period, is matched with the “S” position shown in FIG.
[0039]
As described above, the valve timing control device for the internal combustion engine of the present embodiment is based on the variable valve timing control mechanism 30 that can change the opening / closing timing of the exhaust valve 24 of the internal combustion engine 10 and the rotation angle of the crankshaft 27 of the internal combustion engine 10. A crank angle sensor 28 as a crank angle detecting means for detecting a certain crank angle CA, an in-cylinder pressure sensor 29 as a combustion chamber pressure detecting means for directly detecting the pressure in the combustion chamber 22 of the internal combustion engine 10 as an in-cylinder pressure P, The in-cylinder pressure P decreases during the combustion stroke of the internal combustion engine 10 and a negative pressure is detected by the in-cylinder pressure sensor 29, and the variable valve timing control mechanism 30 is controlled so that the opening timing of the exhaust valve 24 coincides with this time. The valve timing control means achieved by the ECU 40 is provided.
[0040]
That is, when the pressure P in the combustion chamber 22 decreases during the combustion stroke of the internal combustion engine 10 and becomes negative, the in-cylinder pressure sensor 29 detects the time, and the opening timing of the exhaust valve 24 coincides with this negative pressure. Thus, the variable valve timing control mechanism 30 is controlled. As a result, the pressure P in the combustion chamber 22 in the low load region of the internal combustion engine 10 does not become a negative pressure, and the pumping loss as an exhaust loss can be eliminated. Therefore, the combustion deterioration in the low load region of the internal combustion engine The fuel consumption can be reduced without incurring.
[0041]
Next, a flowchart of FIG. 9 showing the processing procedure of the retard control by the variable valve timing control mechanism 30 in the ECU 40 used in the valve timing control apparatus for an internal combustion engine according to the second example of the embodiment of the present invention. This will be described with reference to FIG. This retard angle control routine is repeatedly executed by the ECU 40 every predetermined time.
[0042]
In FIG. 9, first, in step S401, the current crank angle CA from the crank angle sensor 28 is read. Next, the process proceeds to step S402, and it is determined whether the internal combustion engine 10 is in the combustion stroke from the crank angle CA read in step S401. When the determination condition of step S402 is not satisfied, that is, when the internal combustion engine 10 is in the exhaust stroke, the routine proceeds to step S403, the exhaust valve 24 is opened, and this routine is terminated.
[0043]
On the other hand, when the determination condition of step S402 is satisfied, that is, when the internal combustion engine 10 is in the combustion stroke, the routine proceeds to step S404, where the in-cylinder pressure (pressure in the combustion chamber 22) P from the in-cylinder pressure sensor 29 is read. Next, the process proceeds to step S405, and it is determined whether the in-cylinder pressure P read in step S404 is, for example, equal to or lower than the atmospheric pressure as the reference pressure. If the determination condition in step S405 is not satisfied, that is, if the in-cylinder pressure P exceeds the atmospheric pressure and is still large, the process returns to step S401, and the same processing is repeatedly executed.
[0044]
On the other hand, when the determination condition in step S405 is satisfied, that is, when the in-cylinder pressure P becomes smaller than the atmospheric pressure, the exhaust valve 24 is opened after the BDC (Bottom Dead Center) shown in FIG. In step S406, the current crank angle CA from the crank angle sensor 28 is read. Next, the process proceeds to step S407, and it is determined whether the internal combustion engine 10 is in the exhaust stroke from the crank angle CA read in step S406. When the determination condition of step S407 is not satisfied, that is, when the internal combustion engine 10 is still in the combustion stroke, the process returns to step S406, and the same processing is repeatedly executed.
[0045]
When the determination condition of step S407 is satisfied, that is, when the internal combustion engine 10 is in the exhaust stroke, the routine proceeds to step S408, where the in-cylinder pressure P from the in-cylinder pressure sensor 29 is read. Next, the process proceeds to step S409, and it is determined whether the in-cylinder pressure P is equal to or higher than the atmospheric pressure. When the determination condition of step S409 is not satisfied, that is, when the in-cylinder pressure P is less than the atmospheric pressure, the process returns to step S408, and the same processing is repeatedly executed.
[0046]
On the other hand, when the determination condition of step S409 is satisfied, that is, when the in-cylinder pressure P becomes larger than the atmospheric pressure, the routine proceeds to step S410, where the valve drive signal VD is output to open the exhaust valve 24, and this routine is executed. finish. The crank angle CA, which is the opening timing of the exhaust valve 24 during the opening period, is matched with the “T” position shown in FIG.
[0047]
As described above, the valve timing control device for the internal combustion engine of the present embodiment is based on the variable valve timing control mechanism 30 that can change the opening / closing timing of the exhaust valve 24 of the internal combustion engine 10 and the rotation angle of the crankshaft 27 of the internal combustion engine 10. A crank angle sensor 28 as a crank angle detecting means for detecting a certain crank angle CA, an in-cylinder pressure sensor 29 as a combustion chamber pressure detecting means for directly detecting the pressure in the combustion chamber 22 of the internal combustion engine 10 as an in-cylinder pressure P, The in-cylinder pressure P decreases during the combustion stroke of the internal combustion engine 10 and once becomes negative pressure, and then the time point when the pressure P in the combustion chamber 22 recovers to near atmospheric pressure in the subsequent exhaust stroke is detected by the in-cylinder pressure sensor 29. Valve timing achieved by the ECU 40 that controls the variable valve timing control mechanism 30 so that the opening timing of the exhaust valve 24 coincides with this time. It is intended to and a control means.
[0048]
That is, after the pressure P in the combustion chamber 22 drops during the combustion stroke of the internal combustion engine 10 and once becomes negative pressure, the point in time when the pressure P in the combustion chamber 22 recovers to near atmospheric pressure in the subsequent exhaust stroke The variable valve timing control mechanism 30 is controlled so that the opening timing of the exhaust valve 24 coincides with the time point detected by the sensor 29 and recovered to near atmospheric pressure. As a result, the exhaust valve 24 is not opened during the period in which the pressure P in the combustion chamber 22 in the low load region of the internal combustion engine 10 is negative, and the pumping loss as an exhaust loss can be eliminated. The fuel consumption can be reduced without causing deterioration of combustion in the low load region of the internal combustion engine.
[0049]
Here, the effect of reducing the fuel consumption by the above embodiment will be described with reference to the characteristic diagram of FIG. 10 showing the relationship between the opening timing of the exhaust valve 24 during the opening period and the fuel consumption [g / min]. In order to obtain this characteristic diagram, specifically, the internal combustion engine 10 has a total displacement of 1.5 [l], in-line four cylinders, a compression ratio ε = 10.5, and operating conditions of 1000 [rpm], 0 ( No load) [Nm], and oil water temperature 80 [° C.].
[0050]
As shown in FIG. 10, according to the advance angle control for advancing the opening timing of the open period by the normal control for the exhaust valve 24, the crank angle [° CA] at this time is set to the best advance value (see “ It was found that the fuel consumption can be reduced by 2 [%] by setting to the “S” position) than in the “STD” position, which is the opening timing of the open period by the normal control. Further, as shown in FIG. 10, according to the retard angle control for retarding the opening timing of the open period by the normal control for the exhaust valve 24, the crank angle [° CA] at this time is set to the best retard angle value (see FIG. 3). It was found that the fuel consumption can be reduced by 5 [%] by setting to the “T” position shown in the figure, compared with the “STD” position, which is the opening timing of the open period by the normal control.
[0051]
In the above embodiment, for the sake of convenience, the control for the exhaust valve of one cylinder constituting the internal combustion engine has been described. However, the present invention is not limited to this, and the internal combustion engine includes a plurality of cylinders. Therefore, the same effect can be expected by performing the same control on the exhaust valve of each cylinder.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an internal combustion engine and its peripheral devices to which a valve timing control device for an internal combustion engine according to a first example of an embodiment of the invention is applied.
FIG. 2 is a characteristic diagram showing a pressure change in a combustion chamber in a low load region of the internal combustion engine to which the valve timing control device for an internal combustion engine according to the first example of the embodiment of the present invention is applied.
FIG. 3 is an enlarged detail view of part A in FIG.
FIG. 4 is a characteristic diagram showing a change in pressure in the combustion chamber in a medium and high load region of the internal combustion engine to which the valve timing control device for an internal combustion engine according to the first example of the embodiment of the present invention is applied.
FIG. 5 is a flowchart showing a processing procedure of advance angle control by a variable valve timing control mechanism in an ECU used in the valve timing control device for an internal combustion engine according to the first example of the embodiment of the present invention; is there.
FIG. 6 is a flowchart showing a processing procedure of retardation control by a variable valve timing control mechanism in the ECU used in the valve timing control device for an internal combustion engine according to the first example of the embodiment of the present invention; is there.
FIG. 7 is a schematic configuration diagram showing an internal combustion engine to which the valve timing control device for an internal combustion engine according to a second example of the embodiment of the present invention is applied and its peripheral devices.
FIG. 8 is a flowchart showing a processing procedure of the advance angle control by the variable valve timing control mechanism in the ECU used in the valve timing control device for an internal combustion engine according to the second example of the embodiment of the invention. is there.
FIG. 9 is a flowchart showing a processing procedure of retardation control by a variable valve timing control mechanism in the ECU used in the valve timing control device for an internal combustion engine according to the second example of the embodiment of the invention. is there.
FIG. 10 is a fuel consumption amount by the advance control and retard control of the exhaust valve opening timing in the valve timing control device for an internal combustion engine according to the first to second examples of the embodiment of the present invention; It is a characteristic view which shows the reduction effect of.
[Explanation of symbols]
10 Internal combustion engine
13 Air flow meter
22 Combustion chamber
24 Exhaust valve
27 Crankshaft
28 Crank angle sensor
29 In-cylinder pressure sensor
30 Variable valve timing control mechanism
40 ECU (Electronic Control Unit)

Claims (5)

A variable valve timing control mechanism capable of changing the opening and closing timing of the exhaust valve of the internal combustion engine;
Crank angle detecting means for detecting a crank angle which is a rotation angle of a crankshaft of the internal combustion engine;
A crank angle calculation means for calculating a crank angle immediately before the pressure in the combustion chamber drops and becomes negative pressure in the combustion stroke of the internal combustion engine as a target crank angle based on various operating parameters;
Valve timing control means for controlling the variable valve timing control mechanism so that the crank angle at the opening timing of the exhaust valve detected by the crank angle detection means matches the target crank angle calculated by the crank angle calculation means; A valve timing control device for an internal combustion engine, comprising: A variable valve timing control mechanism capable of changing the opening and closing timing of the exhaust valve of the internal combustion engine;
Crank angle detecting means for detecting a crank angle which is a rotation angle of a crankshaft of the internal combustion engine;
Based on various operating parameters, the crank angle when the pressure in the combustion chamber drops during the combustion stroke of the internal combustion engine and once becomes negative pressure, and then the pressure in the combustion chamber recovers to near atmospheric pressure in the subsequent exhaust stroke. A crank angle calculating means for calculating the crank angle;
Valve timing control means for controlling the variable valve timing control mechanism so that the crank angle at the opening timing of the exhaust valve detected by the crank angle detection means matches the target crank angle calculated by the crank angle calculation means; A valve timing control device for an internal combustion engine, comprising: 3. The internal combustion engine according to claim 1, wherein the various operation parameters are at least one of a load of the internal combustion engine based on an intake air amount and an intake pressure, or the load and an engine speed. 4. Valve timing control device for engines. A variable valve timing control mechanism capable of changing the opening and closing timing of the exhaust valve of the internal combustion engine;
Crank angle detecting means for detecting a crank angle which is a rotation angle of a crankshaft of the internal combustion engine;
Combustion chamber pressure detection means for directly detecting the pressure in the combustion chamber of the internal combustion engine;
The time when the pressure in the combustion chamber drops and becomes negative in the combustion stroke of the internal combustion engine is detected by the combustion chamber pressure detecting means, and the variable valve timing control is performed so that the opening timing of the exhaust valve coincides with this time. A valve timing control device for an internal combustion engine, comprising: valve timing control means for controlling the mechanism. A variable valve timing control mechanism capable of changing the opening and closing timing of the exhaust valve of the internal combustion engine;
Crank angle detecting means for detecting a crank angle which is a rotation angle of a crankshaft of the internal combustion engine;
Combustion chamber pressure detection means for directly detecting the pressure in the combustion chamber of the internal combustion engine;
The combustion chamber pressure detection means detects when the pressure in the combustion chamber drops during the combustion stroke of the internal combustion engine and once becomes negative pressure, and then the pressure in the combustion chamber recovers to near atmospheric pressure in the subsequent exhaust stroke. And a valve timing control means for controlling the variable valve timing control mechanism so that the opening timing of the exhaust valve coincides with this timing.

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