JP2008215171A - Internal combustion engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine control device ensuring the amount of internal EGR required even when a load is large, and providing reduced pump loss. <P>SOLUTION: An intake air control valve 2 controlling intake air volume led to flow into a cylinder is provided in an intake pipe in the vicinity of the intake valve of an internal combustion engine provided with at least one cylinder having an intake valve and an exhaust valve. A control unit 11 includes a required intake air volume determining means 21 determining the required intake air volume, an amount of internal EGR required determining means 22 determining the amount of internal EGR required, and an intake control valve control means 23 determining the opening timing of the intake control valvae 2 based on the required intake air volume and the amount of internal EGR required. The intake control valve 2 is opened after intake valve closing timing and closed until the next intake valve closing timing, thereby controlling the intake air volume led to flow into the cylinder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device that controls the amount of intake air flowing from an intake valve into a cylinder of an internal combustion engine by opening and closing an intake control valve provided in an intake pipe near the intake valve of the internal combustion engine. is there.

  In general, in an internal combustion engine, if the internal EGR amount (the amount of burnt gas that blows back from the exhaust pipe into the cylinder or the intake pipe) is too large with respect to the intake air amount, combustion worsens, and further, misfires cause It may adversely affect fuel consumption and exhaust gas characteristics.

  Therefore, conventionally, in order to stabilize the operation state at idling (low load and low rotation), in addition to the first throttle valve that secures air supply to the internal combustion engine, an intake pipe near the intake valve of the internal combustion engine is provided. A second throttle valve is provided, the second throttle valve starts to open after an overlap period of the intake valve and the exhaust valve, and the second throttle valve is completely closed after a predetermined time has elapsed from the closing timing of the intake valve; By accumulating air in the intake pipe between the second throttle valve and the intake valve to increase the intake pipe pressure, the burnt gas remaining in the cylinder and the exhaust pipe is excessively transferred to the intake pipe side through the intake valve. There has been proposed an internal combustion engine control device that suppresses rebound (see, for example, Patent Document 1).

  In general, it is known that internal EGR contributes to fuel efficiency improvement by reducing cooling loss and NOx emission is reduced when the influence on combustion deterioration due to internal EGR is small. Further, as the required intake air amount increases as the load of the internal combustion engine increases (in a high-load operation state), the amount of internal EGR required to reduce NOx emissions and improve fuel efficiency may increase. Are known. Therefore, as the load on the internal combustion engine increases, it is desirable to increase the internal EGR amount to some extent in order to improve fuel consumption and reduce NOx emissions.

  However, in the conventional device described in Patent Document 1, the pressure in the intake pipe is increased by accumulating air in the intake pipe between the second throttle valve and the intake valve before the opening timing of the intake valve. Since the internal EGR amount is suppressed, the internal EGR amount cannot be increased in an operating state where the load of the internal combustion engine is large. Further, since the required intake amount increases as the load increases, the pressure of the intake pipe between the second throttle valve and the intake valve at the opening timing of the intake valve further increases and blows back to the intake pipe side. Since the burnt gas decreases, the amount of internal EGR decreases as the load increases.

  For example, in order to reduce the pump loss by reducing the difference between the space pressure on the combustion chamber side sandwiching the piston in the cylinder and the atmospheric pressure (space pressure on the crankshaft side sandwiching the piston), An intake control valve (for example, a throttle valve or a solenoid valve) that adjusts the amount of intake air into the cylinder is provided in the intake pipe near the intake valve, and the intake control valve starts to open before the intake valve opening timing. The intake control valve is closed when the required intake air amount flows into the downstream portion of the intake control valve from the upstream portion of the intake control valve via the intake control valve, and air is supplied during the closed period of the intake valve. It is also conceivable that air is allowed to flow into the cylinder in a short time by accumulating in the downstream portion of the engine and shortening the overlap period between the intake control valve and the intake valve.

  In this case, the intake control valve starts to open before the opening timing of the intake valve, and air is accumulated in the downstream portion of the intake control valve during the closing period of the intake valve, but the required intake amount increases as the load increases. Therefore, the amount of air accumulated in the downstream portion of the intake control valve during the intake valve closing period increases, and the pressure in the downstream portion of the intake control valve becomes higher at the opening timing of the intake valve. Similarly, the amount of internal EGR decreases as the amount of burned gas that blows back toward the intake pipe decreases and becomes higher.

  That is, in the latter case, as in the conventional device described in Patent Document 1, in a low-load operation state in which the load of the internal combustion engine is small, air is accumulated in the downstream portion of the intake control valve during the intake valve closing period. Although the combustion gas can be prevented from excessively blowing back and the pump loss can be reduced, in the high load operation state, the required internal EGR is obtained by accumulating air downstream of the intake control valve during the closed period of the intake valve. The amount (internal EGR amount during one cycle required for reducing NOx emission and improving fuel consumption) cannot be secured.

  Here, even if the load is large, if the pump loss is reduced while ensuring the required internal EGR amount, it goes without saying that the system will be excellent in reducing NOx emissions and improving fuel efficiency. Considering two points, it becomes a problem to adjust the amount of air accumulated in the downstream portion of the intake control valve during the closing period of the intake valve.

The first point is to suppress the air flowing into the downstream portion of the intake control valve during the closing period of the intake valve and increase the amount of burned gas that blows back to the downstream portion of the intake control valve after the opening timing of the intake valve. The required internal EGR amount is ensured.
The second point is that the intake air at the opening timing of the intake valve is caused by the air accumulated in the downstream portion of the intake control valve during the closing period of the intake valve and the already burned gas blown back to the downstream portion of the intake control valve after the opening timing of the intake valve. By increasing the pressure in the downstream of the control valve, the pump loss is reduced by reducing the difference between the space pressure on the combustion chamber side that sandwiches the piston in the cylinder and the atmospheric pressure (space pressure on the crankshaft side that sandwiches the piston). It is to reduce.

Japanese Patent Laid-Open No. 10-288055

  In the conventional internal combustion engine control device, in the case of Patent Document 1, the pressure in the intake pipe is increased by accumulating air in the intake pipe between the second throttle valve and the intake valve before the opening timing of the intake valve. Since the internal EGR amount is suppressed, the internal EGR amount cannot be increased in a high-load operation state, and the required intake air amount increases as the load increases. There is a problem that the pressure of the intake pipe between the throttle valve and the intake valve of No. 2 increases and the amount of burnt gas that blows back to the intake pipe decreases, and the amount of internal EGR that should be increased decreases as the load increases. .

  In addition, an intake control valve that adjusts the amount of intake air into the cylinder is provided in an intake pipe near the intake valve of the internal combustion engine, and the intake control valve starts to open before the opening timing of the intake valve. It is conceivable to store air in the downstream part of the intake control valve at the same time, but since the required intake amount increases as the load increases, the amount of air stored in the downstream part of the intake control valve increases during the intake valve closing period. Since the pressure in the downstream portion of the intake control valve becomes higher at the opening timing of the intake valve, as in the case of Patent Document 1, the amount of burnt gas that blows back to the intake pipe side decreases, and the internal EGR amount increases as the load increases. There was a problem that there was less.

  Further, in the conventional internal combustion engine control device, the air flowing into the downstream portion of the intake control valve during the closing period of the intake valve is suppressed, and the burned gas that blows back to the downstream portion of the intake control valve after the opening timing of the intake valve is reduced. Ensuring the required internal EGR amount by increasing the amount of air, the air accumulated in the downstream portion of the intake control valve during the closing period of the intake valve, and the burned gas blown back to the downstream portion of the intake control valve after the intake valve is opened Accordingly, by increasing the pressure in the downstream portion of the intake control valve at the opening timing of the intake valve, the difference between the space pressure on the combustion chamber side across the piston in the cylinder and the atmospheric pressure is reduced, and the pump loss is reduced. There is a problem that it is impossible to adjust the amount of air accumulated in the downstream portion of the intake control valve during the intake valve closing period.

  The present invention has been made to solve the above-mentioned problems. Even when the load is large, the required internal EGR amount is ensured and the pump loss is reduced, thereby improving fuel consumption and reducing NOx emissions. An object of the present invention is to obtain an internal combustion engine control device excellent in the above.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus for controlling an internal combustion engine having one or more cylinders having an intake valve and an exhaust valve, and various sensors for detecting an operating state of the internal combustion engine, An intake control valve that is provided in a nearby intake pipe and controls the amount of intake air flowing into the cylinder, and a control unit that controls the opening and closing of the intake control valve according to the operating state, the control unit according to the operating state Based on the required intake air amount determining means for determining the required required intake air amount, the required internal EGR amount determining means for determining the required internal EGR amount required in accordance with the operating state, and the required intake air amount and the required internal EGR amount Intake control valve control means for determining the opening timing of the intake control valve, and the intake control valve control means is configured to change the intake control valve after the closing timing of the intake valve according to the opening timing of the intake control valve. Open, is intended to close the intake control valve in until the next closing timing of the intake valve.

  According to the present invention, even when the load is large, the required internal EGR amount of the internal combustion engine can be ensured and the pump loss can be reduced, thereby improving the fuel efficiency and reducing the NOx emission amount.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
1 is a block diagram showing an internal combustion engine control apparatus according to Embodiment 1 of the present invention, and typically shows a sectional configuration corresponding to one cylinder 1 of the internal combustion engine together with peripheral elements.

  In FIG. 1, an internal combustion engine includes a cylinder 1, a solenoid valve (intake control valve) 2 that adjusts an intake amount into the cylinder 1, a fuel injection valve 3 that adjusts a fuel injection amount and fuel injection timing, and a cylinder 1. An intake valve 4 for adjusting the amount of intake air flowing into the cylinder and the intake timing, an exhaust valve 5 for adjusting the amount of exhaust gas discharged from the cylinder 1 and the exhaust timing, and an air-fuel mixture in the cylinder 1 for burning. And a spark plug 6 for generating sparks.

  The intake pipe 16 on the downstream side of the solenoid valve 2 is provided with a solenoid valve downstream portion 2a, and the intake pipe on the upstream side of the solenoid valve 2 is provided with a surge tank 7 for temporarily storing air. The surge tank 7 constitutes an intake system for a plurality of cylinders (for example, 4 cylinders), and communicates with the cylinder 1 via the solenoid valve 2 and the intake valve 4.

  The upstream side of the surge tank 7 communicates with the atmosphere, and the pressure of the air stored in the surge tank 7 is atmospheric pressure. An air flow sensor 8 that detects the amount of intake air flowing into the surge tank 7 is provided in the intake pipe upstream of the surge tank 7.

  A crankshaft 9a is provided below the cylinder 1, and a crank angle sensor 10 that generates a crank angle detection signal (engine speed) is provided in the vicinity of the crankshaft 9a. The cylinder 1 is provided with a piston 9b that is connected to the crankshaft 9a and reciprocates within the cylinder 1. An in-cylinder space (combustion space) 1a is formed in the cylinder 1 opposite to the crankshaft 9a with respect to the piston 9b. A water temperature sensor 18 that generates a water temperature detection signal of the cooling water temperature of the internal combustion engine is provided outside the cylinder 1.

  Various sensors such as an air flow sensor 8, a crank angle sensor 10, a water temperature sensor 18 and an accelerator sensor (not shown) are electrically connected to the control unit 11, and various detection signals (intake air) indicating the operating state of the internal combustion engine. An amount detection signal, a crank angle detection signal, a water temperature detection signal, an accelerator depression amount, and the like) are input to the control unit 11. The solenoid valve 2 is electrically connected to the control unit 11 and is driven by a solenoid valve control signal from the control unit 11.

  The control unit 11 requests the required intake air amount map having the value of the intake air amount (required intake air amount) with the accelerator depression amount and the engine rotational speed as parameters, and the required intake air amount, the engine rotational speed, and the water temperature as parameters. A required internal EGR amount map having a value of the internal EGR amount (required internal EGR amount) and a solenoid valve control map for driving the solenoid valve 2 are provided.

  The solenoid valve control map in the control unit 11 includes values of the opening timing and closing timing of the solenoid valve 2 with the required intake air amount, the required internal EGR amount and the engine speed as parameters, and the opening speed and closing of the solenoid valve 2. Speed value. It is assumed that the required internal EGR amount in each operation region of the internal combustion engine is obtained in advance by an actual machine test or the like.

FIG. 2 is a functional block diagram showing a specific configuration of the control unit 11.
In FIG. 2, the control unit 11 is connected to required intake air amount determining means 21 and required internal EGR amount determining means 22 connected to various sensors 20, and required intake air amount determining means 21 and required internal EGR amount determining means 22. And an intake control valve control means 23.

Various sensors 20 for detecting the operating state of the internal combustion engine include the air flow sensor 8, the crank angle sensor 10, the water temperature sensor 18 and the like in FIG.
The required intake air amount determining means 21 includes a required intake air amount map, determines the required intake air amount required according to the operating state from the various sensors 20, and inputs it to the intake control valve control means 23.
The required internal EGR amount determining means 22 includes a required internal EGR amount map, determines the required internal EGR amount required according to the operation state from the various sensors 20, and inputs it to the intake control valve control means 23.

The intake control valve control means 23 includes a solenoid valve control map. Based on the required intake air amount from the required intake air amount determination means 21 and the required internal EGR amount from the required internal EGR amount determination means 22, the solenoid valve ( The opening timing of the intake control valve 2) is determined.
Specifically, the intake control valve control means 23 opens the intake control valve 2 after the closing timing of the intake valve 4 in accordance with the opening timing of the solenoid valve 2, and performs intake by the next closing timing of the intake valve 4. The opening time is determined so that the control valve 2 is closed.

3 is an enlarged view showing a specific configuration of the solenoid valve 2. FIG. 3 (a) is a side sectional view of the solenoid valve 2, and FIG. 3 (b) is taken along line AA 'in FIG. 3 (a). It is sectional drawing.
In FIG. 3, the solenoid valve 2 includes a plunger 12, an exciting coil 13 and a spring 14 that drive the plunger 12, a bracket 15 that guides the plunger 12, and a valve seat 17 that is provided inside the intake pipe 16. Has been.

In the above configuration, when a voltage is applied to the exciting coil 13 to generate an electromagnetic force, the plunger 12 is drawn toward the bracket 15 against the urging force of the spring 14, and the solenoid valve 2 is opened.
On the other hand, when the voltage application to the exciting coil 13 is released, the plunger 12 moves to the opposite side of the bracket 15 by the urging force of the spring 14 and comes into contact with the valve seat 17 again, and the solenoid valve 2 is closed.

  Further, by changing the value of the current conducted to the exciting coil 13, the lift amount of the plunger 12 changes, and the opening area S (one-dot chain line frame) between the plunger 12 and the valve seat 17 is adjusted. Further, when the solenoid valve 2 is closed, the air in the intake pipe 16 does not flow into the solenoid valve downstream portion 2a.

  In the solenoid valve 2, as described above, the lift amount of the plunger 12 and the rate of change of the lift amount (the opening speed and the closing speed of the solenoid valve 2) change by changing the current value that is conducted to the exciting coil 13. . Further, by changing the voltage application timing and the voltage release timing to the exciting coil 13, the opening timing, closing timing and opening period of the solenoid valve 2 can be changed.

Next, the operation of the internal combustion engine control apparatus according to Embodiment 1 of the present invention shown in FIGS. 1 and 3 will be described.
First, the crank angle detection signal from the crank angle sensor 10, the intake air amount detection signal from the air flow sensor 8, the accelerator depression amount from the accelerator sensor, and the water temperature detection signal from the water temperature sensor 18 are input to the control unit 11. Is done.

The control unit 11 calculates the required intake air amount from the accelerator depression amount and the engine rotational speed calculated from the crank angle detection signal using the required intake air amount map.
Further, the control unit 11 calculates a water temperature from the water temperature detection signal, and calculates a required internal EGR amount from the calculated required intake air amount, water temperature, and engine speed using a required internal EGR amount map.

  Further, the control unit 11 calculates the opening timing, closing timing, opening speed, and closing speed of the solenoid valve 2 from the calculated required intake air amount, required internal EGR amount, and engine rotation speed using a solenoid valve control map. Then, a solenoid valve control signal for the solenoid valve 2 is output to adjust the amount of intake air flowing into the cylinder 1.

  Thereafter, the control unit 11 calculates the intake air amount flowing into the cylinder 1 using the intake air amount flowing into the surge tank 7 detected from the air flow sensor 8 and the engine rotational speed, and the request calculated as described above. After comparing with the intake air amount, the solenoid valve control signal to the solenoid valve 2 is output again to adjust the intake air amount flowing into the cylinder 1.

Next, referring to FIGS. 4 and 5, the change in the opening area of the solenoid valve 2 and the change in the pressure in the solenoid valve downstream portion 2a in the low load operation state (such as idling) in the first embodiment of the present invention will be described. To do.
First, the change in the opening area of the solenoid valve 2 in the low load operation state will be described with reference to FIG.

FIG. 4 is an explanatory diagram showing the relationship between the opening area S of the solenoid valve 2 and the crank angle θ. The horizontal axis is the crank angle θ, and the vertical axis is the opening area S of the solenoid valve 2.
In FIG. 4, the opening / closing characteristic A (thick line) of the solenoid valve 2 in the low load operation state, the opening timing IVO (one-dot chain line) of the intake valve 4, and the closing timing IVC (one-dot chain line) of the intake valve 4; The closing timing EVC (one-dot chain line) of the exhaust valve 5 and the intake TDC (one-dot chain line) are shown. The intake TDC (one-dot chain line) indicates the time when the piston 9b is located at the top dead center (TDC) in the intake stroke.

In FIG. 4, the open / close characteristic B (thin line) of the solenoid valve 2 is higher than the open / close characteristic A (thick line) in the low-load operation state (the opening timing of the solenoid valve 2 is advanced more than the one-dot chain line IVO). Open / close characteristics in case of control on the side).
Further, the opening / closing characteristic C (broken line) of the solenoid valve 2 controls the higher load operation state than the opening / closing characteristic B (thin line) (the opening timing of the solenoid valve 2 is controlled on the retard side with respect to the opening timing of the intake valve 4). Open / close characteristics in case). The open / close characteristics B and C will be described later.

  In the low-load operation state, as shown by the opening / closing characteristic A (thick line) in FIG. 4, the solenoid valve 2 is opened before the opening timing IVO (one-dot chain line) of the intake valve 4 to the solenoid valve downstream portion 2a. When the required intake air amount flows in, the solenoid valve 2 is closed. At this time, the opening timing of the solenoid valve 2 is set so that the required intake air amount flows into the solenoid valve downstream portion 2a before the opening timing IVO of the intake valve 4.

Next, with reference to FIG. 4 and FIG. 5, a change in pressure in the solenoid valve downstream portion 2a when the opening area of the solenoid valve 2 changes will be described.
FIG. 5 is an explanatory diagram showing the relationship between the pressure P of the solenoid valve downstream portion 2a and the crank angle θ, the horizontal axis is the crank angle θ, and the vertical axis is the pressure P of the solenoid valve downstream portion 2a. Note that the atmospheric pressure (broken line) in FIG. 5 corresponds to the pressure value at the fully open (maximum value) (broken line) in the opening area S of the solenoid valve 2 in FIG.

In FIG. 5, a pressure characteristic P_a (thick line) indicates a change in pressure in the solenoid valve downstream portion 2a when the solenoid valve 2 is opened and closed according to the opening / closing characteristic A (thick line in FIG. 4) in the low load operation state.
A point P_a1 on the pressure characteristic P_a indicates a pressure value of the solenoid valve downstream portion 2a at the opening timing of the solenoid valve 2 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic A (thick line in FIG. 4). A point P_a2 on the pressure characteristic P_a indicates the pressure value of the solenoid valve downstream portion 2a at the closing timing of the solenoid valve 2 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic A.

A point P_a3 on the pressure characteristic P_a indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing IVO (one-dot chain line) of the intake valve 4 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic A. Further, a point P_a4 on the pressure characteristic P_a indicates a pressure value of the solenoid valve downstream portion 2a in the intake TDC (one-dot chain line) when the solenoid valve 2 is opened / closed according to the opening / closing characteristic A.
The pressure characteristics P_b and P_c (corresponding to the open / close characteristics B and C in FIG. 4) indicated by thin lines and broken lines will be described later.

  In FIG. 5, when the solenoid valve 2 is opened and closed according to the opening / closing characteristic A (thick line in FIG. 4), during the period from the closing timing IVC of the intake valve 4 to the opening timing of the solenoid valve 2 in the previous cycle, the solenoid valve 2 Since both the intake valve 4 and the intake valve 4 are closed, the pressure P of the solenoid valve downstream portion 2a remains the pressure value at the point P_a1.

  Subsequently, during the period from the opening timing of the solenoid valve 2 to the closing timing of the solenoid valve 2, air flows into the solenoid valve downstream portion 2a, so that the pressure P of the solenoid valve downstream portion 2a is changed from the point P_a1 to the point P_a2. Change to pressure value.

  Further, during the period from the closing timing of the solenoid valve 2 to the opening timing IVO (one-dot chain line) of the intake valve 4, both the solenoid valve 2 and the intake valve 4 are closed, so that the pressure of the solenoid valve downstream portion 2a P remains the pressure value at the point P_a2 and does not change (pressure value at the point P_a3 = pressure value at the point P_a2).

  Further, in the period from the opening timing IVO (one-dot chain line) of the intake valve 4 to the intake TDC (one-dot chain line), both the intake valve 4 and the exhaust valve 5 are opened, and the exhaust pipe internal pressure is atmospheric pressure (> Therefore, the already burned gas in the cylinder 1 blows back to the solenoid valve downstream portion 2a via the intake valve 4.

  At this time, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_a3 to the pressure value at the point P_a4 due to the blow-back of the already burned gas. During the opening period of the intake valve 4, the solenoid valve downstream portion 2a and the cylinder space 1a are electrically connected, so the pressure in the cylinder space 1a at the intake TDC (one-dot chain line) is also the pressure value at the point P_a4. It becomes.

  Thereby, when the piston 9b descends from the intake TDC (one-dot chain line), the difference between the pressure in the cylinder internal space 1a and the atmospheric pressure (the pressure in the space on the crankshaft 9a side across the piston 9b) is reduced. , Pump loss can be reduced. Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a.

By the way, according to the pressure characteristic P_a (thick line) in FIG. 5 based on the opening / closing characteristic A in FIG. 4, the atmospheric pressure is reached at the intake TDC (one-dot chain line) as indicated by the pressure value at the point P_a4.
Further, since the required intake air amount is reduced on the lower load side than in the case of the open / close characteristic A (thick line in FIG. 4), the intake air flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is the open / close characteristic. The amount of gas remaining in the solenoid valve downstream portion 2a at the closing timing IVC (one-dot chain line) of the intake valve 4 is also smaller than in the case of A.

  In this case, the pressure P of the solenoid valve downstream portion 2a at the closing timing IVC and the opening timing IVO of the intake valve 4 is lower than that in the case of the opening / closing characteristic A. The burnt gas that blows back to the valve downstream portion 2a does not decrease, and the required internal EGR amount can be ensured.

  However, since the required intake air amount increases on the higher load side than in the case of the opening / closing characteristic A, the intake air amount flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is larger than in the case of the opening / closing characteristic A. Thus, the amount of gas remaining in the solenoid valve downstream portion 2a at the closing timing IVC of the intake valve 4 also increases.

  In this case, the pressure P of the solenoid valve downstream portion 2a at the closing timing IVC and the opening timing IVO of the intake valve 4 is higher than that in the case of the opening / closing characteristic A. The burnt gas that blows back to the valve downstream portion 2a is reduced, and the required internal EGR amount cannot be secured.

Therefore, it is desirable to retard the opening timing IVO of the intake valve 4 more than the case of the opening / closing characteristic A as the required intake air amount and the required internal EGR amount increase compared to the case of the opening / closing characteristic A. .
As a result, the amount of intake air flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 can be reduced, and an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 can be suppressed. The burnt gas that can be blown back to the valve downstream portion 2a can be increased.

  4 and 5, the solenoid valve 2 is on the higher load side than when the solenoid valve 2 is opened and closed (when the solenoid valve 2 is opened and closed according to the opening and closing characteristic A in FIG. 4). The change in the opening area S of the solenoid valve 2 and the change in the pressure P in the downstream portion 2a of the solenoid valve when the opening timing is controlled on the more advanced side than the opening timing IVO of the intake valve 4 will be described. .

  First, a change in the opening area S of the solenoid valve 2 in the high load operation state will be described with reference to FIG. As described above, the open / close characteristic B (thin line) in FIG. 4 is on the higher load side than the open / close characteristic A (thick line), and the opening timing of the solenoid valve 2 is set higher than the opening timing IVO of the intake valve 4. The open / close characteristics of the solenoid valve 2 when controlling on the advance side are shown.

In the open / close characteristic B, the opening timing of the solenoid valve 2 is retarded with respect to the open / close characteristic A as the load of the internal combustion engine increases and the required intake air amount and the required EGR amount increase.
The reason for retarding the opening timing of the solenoid valve 2 is that the period from the opening timing of the solenoid valve 2 to the opening timing IVO of the intake valve 4 is shortened so that the solenoid valve downstream portion 2a is closed during the closing period of the intake valve 4. This is to limit the amount of intake air flowing into the.
Thereby, the rise of the pressure P of the solenoid valve downstream part 2a during the closing period of the intake valve 4 can be suppressed.

Next, a change in the pressure P of the solenoid valve downstream portion 2a when the solenoid valve 2 is opened and closed according to the opening / closing characteristics B (thin line in FIG. 4) in the high load operation state will be described with reference to FIG.
In FIG. 5, a pressure characteristic P_b (thin line) indicates a change in pressure of the solenoid valve downstream portion 2 a when the solenoid valve 2 is opened and closed according to the opening and closing characteristic B.

  In the pressure characteristic P_b, a point P_b1 indicates the pressure value of the solenoid valve downstream portion 2a when the solenoid valve 2 is opened and closed when the solenoid valve 2 is opened and closed according to the opening and closing characteristic B. Point P_b2 indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing IVO of the intake valve 4 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic B. Point P_b3 indicates the solenoid valve according to the opening / closing characteristic B. 2 shows the pressure value of the solenoid valve downstream portion 2a in the intake TDC when 2 is opened and closed.

  In FIG. 5, when the solenoid valve 2 is opened and closed according to the opening / closing characteristic B (thin line in FIG. 4) on the higher load side than the opening / closing characteristic A (thick line in FIG. 4), the closing timing of the intake valve 4 in the previous cycle Since both the solenoid valve 2 and the intake valve 4 are closed during the period from IVC to the opening timing of the solenoid valve 2, the pressure P of the solenoid valve downstream portion 2a is the pressure value at the point P_b1 on the pressure characteristic P_b. It remains unchanged.

Subsequently, during the period from the opening timing of the solenoid valve 2 to the opening timing IVO of the intake valve 4, air flows into the solenoid valve downstream portion 2a, so that the pressure P of the solenoid valve downstream portion 2a is the pressure value at the point P_b1. To the pressure value at point P_b2.
In addition, during the period from the opening timing IVO of the intake valve 4 to the intake TDC, both the intake valve 4 and the exhaust valve 5 are open, and the exhaust pipe internal pressure becomes atmospheric pressure (> pressure value at point P_b2). The burnt gas blows back to the solenoid valve downstream portion 2a through the intake valve 4.

Further, since the solenoid valve 2 is opened during the period from the opening timing IVO of the intake valve 4 to the intake TDC, air continues to flow into the solenoid valve downstream portion 2a.
As described above, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_b2 to the pressure value at the point P_b3. That is, the pressure value at the point P_b3 depends on the amount of intake air that flows into the solenoid valve downstream portion 2a and the amount of burned gas that blows back to the solenoid valve downstream portion 2a during the period up to the intake TDC.

  By the way, as the opening timing of the solenoid valve 2 is delayed with respect to the opening timing of the solenoid valve 2 in the opening / closing characteristic A (thick line in FIG. 4), from the opening timing of the solenoid valve 2 to the opening timing IVO of the intake valve 4. And the intake air amount flowing into the solenoid valve downstream portion 2a by the opening timing IVO of the intake valve 4 decreases. As a result, an increase in the pressure value at the point P_b2 is suppressed, so that the amount of burned gas that blows back to the solenoid valve downstream portion 2a increases, and the amount of internal EGR in the cylinder 1 increases.

  Therefore, in the opening / closing characteristic B (inner thin line in FIG. 4), the amount of burnt gas blown back to the solenoid valve downstream portion 2a and the amount of intake air flowing into the solenoid valve downstream portion 2a during the open period of the solenoid valve 2 The opening timing of the solenoid valve 2 is retarded as the load increases and the required intake air amount and the required internal EGR amount increase so that the pressure value of P_b3 becomes atmospheric pressure and the required internal EGR amount can be secured. Let

In the open period of the intake valve 4, the solenoid valve downstream portion 2a and the in-cylinder space 1a are electrically connected, so the pressure in the in-cylinder space 1a at the intake TDC is also the pressure value at the point P_b3.
This reduces the difference between the pressure in the cylinder internal space 1a and the atmospheric pressure (the pressure in the space on the crankshaft 9a side across the piston 9b) when the piston 9b descends from the intake TDC, as in the case of low load. In this way, pump loss can be reduced.
Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a.

Further, when the solenoid valve 2 is opened and closed according to the opening / closing characteristic B, the load of the internal combustion engine is increased and the required intake air amount and the required internal EGR amount are increased. As time increases, the opening timing of the solenoid valve 2 eventually becomes equal to the opening timing IVO of the intake valve 4.
Thereafter, when the load further increases, the opening timing of the solenoid valve 2 is controlled as follows.

  Next, when the solenoid valve 2 is operated at a higher load than when the solenoid valve 2 is opened and closed according to the opening / closing characteristic B in FIG. 4, the solenoid valve 2 is controlled on the retard side with respect to the opening timing IVO of the intake valve 4. The change of the opening area S of the solenoid valve 2 and the change of the pressure P of the solenoid valve downstream portion 2a due to this will be described.

  First, a change in the opening area S of the solenoid valve 2 in a higher load operation state will be described with reference to FIG. As described above, the open / close characteristic C (broken line) in FIG. 4 is a higher load operation state than the open / close characteristic B, and the opening timing of the solenoid valve 2 is later than the opening timing IVO of the intake valve 4. The opening / closing characteristics of the solenoid valve 2 in the case of controlling on the corner side are shown.

  The reason why the opening timing of the solenoid valve 2 is retarded from the opening timing IVO of the intake valve 4 as in the opening / closing characteristic C is that the amount of intake air flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is limited. This is not to suppress an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4. This is because, when the opening timing of the solenoid valve 2 is on the retard side with respect to the opening timing IVO of the intake valve 4, no matter what timing the opening timing of the solenoid valve 2 is, by the opening timing IVO of the intake valve 4 This is because the amount of intake air flowing into the solenoid valve downstream portion 2a is “0”, and the pressure P of the solenoid valve downstream portion 2a at the opening timing IVO of the intake valve 4 does not change.

  However, during the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2, the burnt gas is only blown back to the solenoid valve downstream portion 2a, but after the opening timing of the solenoid valve 2 is reached. The burned gas not only blows back into the solenoid valve downstream portion 2a, but also air flows.

Therefore, even when the opening timing of the solenoid valve 2 is more retarded than the opening timing IVO of the intake valve 4, the more the opening timing of the solenoid valve 2 is retarded, the more the solenoid valve 2 moves from the opening timing IVO of the intake valve 4. Therefore, the amount of burnt gas that blows back to the solenoid valve downstream portion 2a increases and the internal EGR amount increases.
That is, the reason for delaying the opening timing of the solenoid valve 2 from the opening timing IVO of the intake valve 4 is that the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2 is lengthened. This is to increase the amount of burnt gas that blows back into the chamber.

  Here, a change in the pressure P of the solenoid valve downstream portion 2a when the solenoid valve 2 is opened and closed according to the opening / closing characteristic C (broken line in FIG. 4) will be described with reference to FIG. In FIG. 5, a pressure characteristic P_c (broken line) is a pressure change in the solenoid valve downstream portion 2a when the solenoid valve 2 is opened / closed according to the opening / closing characteristic C (broken line in FIG. 4).

  In the pressure characteristic P_c, a point P_c1 indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing IVO of the intake valve 4 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic C, and the point P_c2 Therefore, when the solenoid valve 2 is opened and closed, the pressure value of the solenoid valve downstream portion 2a at the opening timing of the solenoid valve 2 is shown, and the point P_c3 indicates the solenoid valve in the intake TDC when the solenoid valve 2 is opened and closed according to the opening and closing characteristics C The pressure value of the downstream part 2a is shown.

  When the solenoid valve 2 is opened / closed according to the opening / closing characteristic C, the solenoid valve 2 and the intake valve 4 are both closed during the period from the closing timing IVC of the intake valve 4 to the opening timing IVO in the previous cycle. The pressure P of the solenoid valve downstream portion 2a remains unchanged at the pressure value at the point P_c1.

  Subsequently, in the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2, both the intake valve 4 and the exhaust valve 5 are opened, and the exhaust pipe internal pressure is atmospheric pressure (> the pressure value at the point P_c1). Therefore, the burnt gas blows back to the solenoid valve downstream portion 2a through the intake valve 4. Thereby, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_c1 to the pressure value at the point P_c2.

  In the period from the opening timing of the solenoid valve 2 to the intake TDC, air flows into the solenoid valve downstream portion 2a. Further, during the period from the opening timing of the solenoid valve 2 to the intake TDC, both the intake valve 4 and the exhaust valve 5 are opened, and the exhaust pipe internal pressure becomes atmospheric pressure (> pressure value at the point P_c2). The burnt gas blows back to the solenoid valve downstream portion 2a through the intake valve 4.

  As described above, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_c2 to the pressure value at the point P_c3. That is, the pressure value at the point P_c3 depends on the amount of intake air that flows into the solenoid valve downstream portion 2a and the amount of burned gas that blows back to the solenoid valve downstream portion 2a during the period up to the intake TDC.

  By the way, as the opening timing of the solenoid valve 2 is retarded with respect to the opening timing IVO of the intake valve 4, the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2 becomes longer. The amount of burnt gas that blows back to the solenoid valve downstream portion 2a increases.

  Therefore, in the open / close characteristic C, the pressure value at the point P_c3 is large due to the amount of burned gas that blows back to the solenoid valve downstream portion 2a and the amount of intake air that flows into the solenoid valve downstream portion 2a during the opening period of the solenoid valve 2. The opening timing of the solenoid valve 2 is retarded as the load increases and the required intake air amount and the required internal EGR amount increase so that the required internal EGR amount can be secured.

Since the solenoid valve downstream portion 2a and the in-cylinder space 1a are in conduction during the opening period of the intake valve 4, the pressure in the in-cylinder space 1a at the intake TDC is also the pressure value at the point P_c3.
This reduces the difference between the pressure in the cylinder internal space 1a and the atmospheric pressure (the pressure in the space on the crankshaft 9a side across the piston 9b) when the piston 9b descends from the intake TDC, as in the case of low load. In this way, pump loss can be reduced.
Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a.

  By the way, in general, the closing timing EVC of the exhaust valve 5 is set to the retard side with respect to the intake TDC. Therefore, if the opening timing of the solenoid valve 2 is set to the retard side with respect to the intake TDC, the solenoid valve downstream. The amount of already burned gas blown back to the part 2a becomes larger. However, when the opening timing of the solenoid valve 2 is set to be retarded from the intake TDC, since the opening area S of the solenoid valve 2 is not yet large in the first half of the intake stroke, the intake resistance at the solenoid valve 2 increases. In addition, the fuel consumption of the internal combustion engine may be adversely affected.

  Further, as the load of the internal combustion engine becomes larger (high load operation state), the required intake air amount increases and the pressure value at the point P_c1 on the pressure characteristic P_c increases, so even if the intake valve 4 and the exhaust valve 5 are over Even if the opening timing of the solenoid valve 2 is set after the end of the lap period, the required internal EGR amount cannot be secured if the load becomes very large.

  For the above reasons, in the first embodiment of the present invention, the opening timing of the solenoid valve 2 is retarded only to the intake TDC. Therefore, in the operation region where the load is very large, the required internal EGR amount May not be able to be secured.

  Next, the relationship between the load and the internal EGR in the internal combustion engine control apparatus according to Embodiment 1 of the present invention will be described with reference to the explanatory diagram of FIG. FIG. 6 shows the relationship between the load of the internal combustion engine and the internal EGR amount secured in the cylinder 1 at the closing timing IVC of the intake valve 4, where the horizontal axis is the load and the vertical axis is the internal EGR amount.

  In FIG. 6, the internal EGR amount characteristic J (two-dot chain line) by the conventional device (see the above-mentioned Patent Document 1) with respect to the required internal EGR amount H (thick line) and the internal EGR amount characteristic according to the first embodiment of the present invention. K (broken line) is shown in contrast. The internal EGR amount characteristic L (one-dot chain line) in FIG. 6 is related to the second embodiment described later.

In FIG. 6, in the case of internal EGR amount characteristic K (broken line) according to Embodiment 1 of the present invention, the internal EGR amount increases as the load increases, and the internal EGR amount increases from a region where the load increases to some extent. Decrease.
On the other hand, in the case of the internal EGR amount characteristic J (two-dot chain line) by the conventional apparatus, the internal EGR amount decreases as the load increases, and the difference from the required internal EGR amount H increases.

As described above, according to the internal EGR amount characteristic K (broken line) according to Embodiment 1 of the present invention, the internal EGR amount characteristic J (two-dot chain line) of the conventional device (Patent Document 1) even in the high load operation region. As compared with the case of the above, a larger amount of internal EGR can be secured.
Further, when considering the pump loss, also in the internal combustion engine control apparatus according to the first embodiment of the present invention, the pressure in the cylinder internal space 1a at the intake TDC is atmospheric pressure, and according to the required intake air amount, Since the throttle valve is closed when it flows into the downstream portion of the throttle valve via the throttle valve from the upstream portion of the throttle valve, the pump loss can be reduced as in the conventional device (Patent Document 1).

  In general, the required internal EGR amount when the load on the internal combustion engine is the same is smaller when the internal combustion engine is cold than when the internal combustion engine is warm. However, the opening timing of the solenoid valve 2 when the internal combustion engine is cold is warmed. It is possible to cope with this by reducing the amount of internal EGR which is advanced from the time of the machine and blows back to the solenoid downstream portion 2a when the machine is cold.

  Note that the solenoid valve control map in the intake control valve control means 23 of the control unit 11 shows the opening timing, closing timing, and opening speed of the solenoid valve 2 in accordance with the required intake air amount and the required internal EGR amount for each engine speed. The closing speed is set, and these set values are obtained from each engine rotation speed and an actual machine test according to the above contents.

  As described above, the internal combustion engine control apparatus according to Embodiment 1 of the present invention includes at least one cylinder 1 having the intake valve 4 and the exhaust valve 5, and various sensors (air flow sensors) for detecting the operating state of the internal combustion engine. 8, a crank angle sensor 10, a water temperature sensor 18, etc.), an intake control valve (solenoid valve 2) that is provided in the intake pipe 16 in the vicinity of the intake valve 4 and controls the amount of intake air flowing into the cylinder 1, and the operating state And a control unit 11 for controlling opening and closing of the solenoid valve 2 according to the above.

  The control unit 11 includes a required intake air amount determining unit 21 that determines a required intake air amount that is required according to the operating state from the various sensors 20, and a required internal EGR amount that is required according to the operating state. An intake control valve control means 23 for determining the opening timing of the solenoid valve 2 based on the required intake air amount and the required internal EGR amount. The intake control valve control means 23 includes the opening timing of the solenoid valve 2. Accordingly, the solenoid valve 2 is opened after the closing timing of the intake valve 4, and the solenoid valve 2 is closed by the next closing timing of the intake valve 4.

Therefore, according to the first embodiment of the present invention, by determining the opening timing of the solenoid valve 2 according to the required intake air amount and the required internal EGR amount, the required internal EGR amount is ensured even in a high load operation state. , Pump loss can be reduced.
As a result, it is possible to provide an internal combustion engine control device that achieves improved fuel efficiency and reduced NOx emissions.

Further, the intake control valve control means 23 retards the opening timing of the solenoid valve 2 as the required intake air amount increases, and retards the opening timing of the solenoid valve 2 as the required internal EGR amount increases.
Specifically, as the load increases and the required intake air amount and the required internal EGR amount increase, the opening timing of the solenoid valve 2 is retarded from the low load operation state, so that the solenoid valve 2 opens from the opening timing to IVO. To shorten the period.
Thereby, the rise of the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 can be suppressed, and the amount of burned gas blown back to the solenoid valve downstream portion 2a can be increased.

If the required internal EGR amount cannot be ensured even if the load further increases and the opening timing of the solenoid valve 2 is retarded to the opening timing IVO of the intake valve 4, the opening timing of the solenoid valve 2 is reached. Is delayed from the opening timing IVO of the intake valve 4, and the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2 is set longer.
As a result, an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is suppressed, and in the period from the opening timing IVO of the intake valve 4 to the opening timing of the solenoid valve 2, the downstream portion of the solenoid valve Since the burnt gas only blows back to 2a, the amount of burnt gas blown back to the solenoid valve downstream portion 2a can be further increased.

Further, the required internal EGR amount can be ensured by the already burned gas blown back to the solenoid valve downstream portion 2a, and in the intake TDC, the solenoid valve downstream portion by the blow back of the already burned gas and the inflow of air. The opening timing of the solenoid valve 2 is retarded as the required intake air amount and the required internal EGR amount increase so that 2a becomes atmospheric pressure.
Thereby, even in a higher load operation state, the required internal EGR amount can be secured and the pump loss can be reduced.

Even when the required internal EGR amount changes without changing the load, the opening timing of the solenoid valve 2 is delayed as the required internal EGR amount increases, so that the burned gas blown back to the solenoid valve downstream portion 2a The amount can be increased.
Further, the required internal EGR amount can be ensured by the already burned gas blown back to the solenoid valve downstream portion 2a, and in the intake TDC, the solenoid valve downstream portion by the blow back of the already burned gas and the inflow of air. The opening timing of the solenoid valve 2 is retarded as the required internal EGR amount increases so that 2a becomes atmospheric pressure.
Thereby, even if the required internal EGR amount increases without changing the load, the required internal EGR amount can be secured and the pump loss can be reduced.

  Here, the solenoid valve 2 has been described as an example of the intake control valve. However, the present invention is not limited to this. For example, a throttle valve that can be opened and closed at high speed (see Patent Document 1) may be used as the intake control valve.

Embodiment 2. FIG.
In the first embodiment, the opening timing of the solenoid valve 2 is retarded as the load increases and the required intake air amount and the required internal EGR amount increase. However, from the opening timing of the solenoid valve 2 to the intake TDC. The “opening speed” of the solenoid valve 2 may be set slower.

For example, in the case where the opening timing of the solenoid valve 2 is retarded as in the first embodiment, if the opening period of the solenoid valve 2 is shortened, it is difficult to control if the response speed of opening and closing of the solenoid valve 2 is slow. There is a possibility.
Therefore, in Embodiment 2 of the present invention, the opening speed of the solenoid valve 2 from the opening timing of the solenoid valve 2 to the intake TDC is set slower as the load increases and the required intake air amount and the required internal EGR amount increase. To do.

  As a result, an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is suppressed, and air flowing into the solenoid valve downstream portion 2a during the period from the opening timing IVO of the intake valve 4 to the intake TDC. And the amount of burned gas blown back to the solenoid valve downstream portion 2a can be increased. Further, since the opening period of the solenoid valve 2 can be set longer than in the case of the first embodiment, the present invention can be applied even when the response speed of opening and closing of the solenoid valve 2 is slow.

The second embodiment of the present invention will be described below with reference to FIGS. 7 and 8 together with FIGS.
7 and 8 are explanatory diagrams showing the control operation according to the second embodiment of the present invention, and correspond to FIGS. 4 and 5 described above, respectively. The configuration of the internal combustion engine control apparatus according to Embodiment 2 of the present invention is as shown in FIGS. Further, it is assumed that the required internal EGR amount in each operation region is obtained in advance from an actual machine test or the like, as described above.

  FIG. 7 is an explanatory diagram showing the relationship between the opening area S of the solenoid valve 2 and the crank angle θ according to the second embodiment of the present invention. In FIG. 7, an open / close characteristic D (two-dot chain line) indicates the open / close characteristic of the solenoid valve 2 in a low-load operation state. The opening / closing characteristic E (broken line) of the solenoid valve 2 in the high load operation state will be described later.

First, a change in the opening area S of the solenoid valve 2 in a low-load operation state (such as during idling) will be described with reference to FIG.
In the low load operation state, the solenoid valve 2 is opened before the opening timing IVO of the intake valve 4 as indicated by the open / close characteristic D (two-dot chain line).

  Subsequently, when the required intake air amount flows into the solenoid valve downstream portion 2a, the solenoid valve 2 is closed. At this time, the required intake amount may flow into the solenoid valve downstream portion 2a during the closing period of the intake valve 4, and the opening timing of the solenoid valve 2 may be appropriately set according to the response speed of opening and closing of the solenoid valve 2. .

Next, a change in the pressure P of the solenoid valve downstream portion 2a in the low load operation state will be described with reference to FIG.
FIG. 8 is an explanatory diagram showing the relationship between the pressure P of the solenoid valve downstream portion 2a and the crank angle θ. In FIG. 8, a pressure characteristic P_d (two-dot chain line) indicates a pressure change in the solenoid valve downstream portion 2a when the solenoid valve 2 is opened and closed according to the opening / closing characteristic D (two-dot chain line in FIG. 7).

  In the pressure characteristic P_d, the point P_d1 indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing of the solenoid valve 2 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic D, and the point P_d2 indicates the solenoid according to the opening / closing characteristic D The pressure value of the solenoid valve downstream portion 2a at the closing timing of the solenoid valve 2 when the valve 2 is opened and closed is shown.

  A point P_d3 indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing IVO of the intake valve 4 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic D, and a point P_d4 indicates the solenoid valve 2 according to the opening / closing characteristic D. The pressure value of the solenoid valve downstream portion 2a in the intake TDC when the valve is opened and closed is shown.

  In FIG. 8, when the solenoid valve 2 is opened / closed according to the opening / closing characteristic D (two-dot chain line in FIG. 7), the solenoid is operated during the period from the opening timing IVC of the intake valve 4 to the opening timing of the solenoid valve 2 in the previous cycle. Both the valve 2 and the intake valve 4 are closed. Therefore, in the period from the opening timing IVC of the intake valve 4 in the previous cycle to the opening timing of the solenoid valve 2, the pressure P of the solenoid valve downstream portion 2a remains the pressure value at the point P_d1.

Subsequently, since air flows into the solenoid valve downstream portion 2a during the period from the opening timing to the closing timing of the solenoid valve 2, the pressure P of the solenoid valve downstream portion 2a is changed from the pressure value at the point P_d1 to the pressure value at the point P_d2. Change.
Further, since the solenoid valve 2 and the intake valve 4 are both closed during the period from the closing timing of the solenoid valve 2 to the opening timing IVO of the intake valve 4, the pressure P of the solenoid valve downstream portion 2a is the point P_d2. The pressure value remains unchanged (pressure value at point P_d3 = pressure value at point P_d2).

Further, in the period from the opening timing IVO of the intake valve 4 to the intake TDC, both the intake valve 4 and the exhaust valve 5 are opened, and the exhaust pipe internal pressure becomes atmospheric pressure (> pressure value at the point P_d3). The burnt gas blows back to the solenoid valve downstream portion 2a through the intake valve 4.
At this time, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_d3 to the pressure value at the point P_d4 due to the blow-back of the already burned gas. Note that, during the open period of the intake valve 4, the solenoid valve downstream portion 2a and the in-cylinder space 1a are electrically connected, and the pressure in the in-cylinder space 1a at the intake TDC also becomes the pressure value at the point P_d4.

As a result, when the piston 9b descends from the intake TDC, the difference between the pressure in the in-cylinder space 1a and the atmospheric pressure (the pressure in the space on the crankshaft 9a side across the piston 9b) is reduced to reduce pump loss. Can be made.
Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a.

By the way, according to the pressure characteristic P_d in FIG. 8 based on the open / close characteristic D in FIG. 7, the atmospheric pressure is reached at the intake TDC as shown by the pressure value at the point P_d4.
Further, since the required intake air amount is reduced on the lower load side than in the case of the opening / closing characteristic D, the intake air amount flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is smaller than in the case of the opening / closing characteristic D. The amount of gas remaining in the solenoid valve downstream portion 2a at the closing timing IVC of the intake valve 1 is also reduced.

  As a result, the pressure P of the solenoid valve downstream portion 2a at the closing timing IVC and the opening timing IVO of the intake valve 4 is lower than that in the case of the opening / closing characteristic A. The burnt gas that blows back to the valve downstream portion 2a does not decrease, and the required internal EGR amount can be ensured.

  However, since the required intake air amount increases on the higher load side than in the case of the opening / closing characteristic D, the intake air amount flowing into the solenoid valve downstream portion 2a during the closing period of the intake valve 4 becomes larger than in the case of the opening / closing characteristic D. The amount of gas remaining in the solenoid valve downstream portion 2a at the closing timing IVC of the intake valve 4 also increases.

  In this case, the pressure P of the solenoid valve downstream portion 2a at the closing timing IVC and the opening timing IVO of the intake valve 4 is higher than that in the case of the opening / closing characteristic D. The burnt gas that blows back to the valve downstream portion 2a is reduced, and the required internal EGR amount cannot be secured.

Therefore, the intake control valve control means 23 (see FIG. 2) according to Embodiment 2 of the present invention is higher in load side than the case of the opening / closing characteristic D, and the required intake air amount and the required internal EGR amount increase. Control is performed so that the opening speed of the solenoid valve 2 from the opening timing of the solenoid valve 2 to the intake TDC becomes slow.
As a result, an increase in pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is suppressed, and air flowing into the solenoid valve downstream portion 2a during the period from the opening timing IVO of the intake valve 4 to the intake TDC is reduced. It can suppress and can increase the quantity of the burnt gas which blows back to the solenoid valve downstream part 2a.

Hereinafter, referring to FIG. 7 and FIG. 8, the change in the opening area S of the solenoid valve 2 on the high load side as compared with the case where the solenoid valve 2 is opened and closed according to the opening / closing characteristic D, and the solenoid valve downstream portion 2a thereby A change in the pressure P will be described.
First, a change in the opening area S of the solenoid valve 2 will be described with reference to FIG. In FIG. 7, the open / close characteristic E (broken line) indicates the open / close characteristic of the solenoid valve 2 on the higher load side than the open / close characteristic D.

When the load of the internal combustion engine increases, as shown in the opening / closing characteristic E, the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC is slower than in the case of the opening / closing characteristic D (open / close Set the characteristic slope to be small).
Subsequently, during the period from the intake TDC, as shown in the opening / closing characteristic E, the solenoid valve 2 is opened at the fastest opening speed (maximum inclination of the opening / closing characteristics), and then the fastest closing speed of the solenoid valve 2 is reached. To close the solenoid valve 2.

  Thereby, compared with the case of the above-mentioned Embodiment 1, the opening period of the solenoid valve 2 can be lengthened, and the control according to the present invention can be applied even when the response speed of opening and closing of the solenoid valve 2 is slow. it can.

  Here, the reason why the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC is set slower than in the case of the opening / closing characteristics D at low load is that the intake timing from the opening timing of the solenoid valve 2 By restricting the air flowing into the solenoid valve downstream portion 2a during the period up to TDC, an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is suppressed, and the intake valve 4 from the opening timing IVO. This is to suppress the inflow of air to the solenoid valve downstream portion 2a during the period up to the intake TDC.

The reason for opening the solenoid valve 2 at the fastest opening speed in the period from the intake TDC is to increase the opening area S of the solenoid valve 2 and to reduce the intake resistance at the solenoid valve 2 in the intake stroke. is there.
Furthermore, the reason for closing the solenoid valve 2 at the fastest closing speed is to shorten the overlap period between the solenoid valve 2 and the intake valve 4 to reduce the pump loss.

  If the required intake air amount flows into the cylinder 1 by closing the solenoid valve 2 at the fastest closing speed during the period from the intake TDC, the solenoid at the fastest opening speed during the period from the intake TDC. There is no need to open the valve 2.

Next, a change in the pressure P of the solenoid valve downstream portion 2a when the solenoid valve 2 is opened / closed according to the opening / closing characteristic E (broken line in FIG. 7) will be described with reference to FIG.
In FIG. 8, a pressure characteristic P_e (broken line) indicates a change in pressure of the solenoid valve downstream portion 2a when the solenoid valve 2 is opened / closed according to the opening / closing characteristic E.

  In the pressure characteristic P_e, the point P_e1 indicates the pressure value of the solenoid valve downstream portion 2a at the opening timing of the solenoid valve 2 when the solenoid valve 2 is opened / closed according to the opening / closing characteristic E, and the point P_e2 indicates the solenoid according to the opening / closing characteristic E The pressure value of the solenoid valve downstream portion 2a at the opening timing IVO of the intake valve 4 when the valve 2 is opened / closed is shown, and the point P_e3 is the downstream portion of the solenoid valve in the intake TDC when the solenoid valve 2 is opened / closed according to the opening / closing characteristic E The pressure value of 2a is shown.

  When the solenoid valve 2 is opened / closed according to the opening / closing characteristic E, the solenoid valve 2 and the intake valve 4 are both closed during the period from the closing timing IVC of the intake valve 4 in the previous cycle to the opening timing of the solenoid valve 2. The pressure P of the solenoid valve downstream portion 2a remains unchanged at the pressure value at the point P_e1.

Subsequently, during the period from the opening timing of the solenoid valve 2 to the opening timing IVO of the intake valve 4, air flows into the solenoid valve downstream portion 2a, so that the pressure P of the solenoid valve downstream portion 2a is the pressure value at the point P_e1. To the pressure value at the point P_e2.
In addition, during the period from the opening timing IVO of the intake valve 4 to the intake TDC, both the intake valve 4 and the exhaust valve 5 are open, and the exhaust pipe internal pressure becomes atmospheric pressure (> pressure value at point P_e2). The burnt gas blows back to the solenoid valve downstream portion 2a through the intake valve 4.

Further, since the solenoid valve 2 is opened during the period from the opening timing IVO of the intake valve 4 to the intake TDC, air continues to flow into the solenoid valve downstream portion 2a.
Thus, the pressure P of the solenoid valve downstream portion 2a changes from the pressure value at the point P_e2 to the pressure value at the point P_e3. That is, the pressure value at the point P_e3 depends on the amount of intake air that flows into the solenoid valve downstream portion 2a before the intake TDC and the amount of burned gas that blows back to the solenoid valve downstream portion 2a.

Here, the slower the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC, the lower the solenoid valve 2 opening speed in the period from the opening timing of the solenoid valve 2 to the intake TDC. The amount of intake air that flows in decreases.
As a result, an increase in the pressure value at the point P_e2 is also suppressed, and the amount of intake air flowing into the solenoid valve downstream portion 2a during the period from the opening timing IVO of the intake valve 4 to the intake TDC is reduced, and the solenoid valve downstream portion 2a is reduced. The amount of burnt gas that blows back increases.

  Therefore, in the opening / closing characteristic E at the time of high load, the pressure at the point P_e3 is determined by the amount of burned gas that blows back to the solenoid valve downstream portion 2a and the amount of intake air that flows into the solenoid valve downstream portion 2a during the opening period of the solenoid valve 2. The period from the opening timing of the solenoid valve 2 to the intake TDC as the load increases and the required intake air amount and the required internal EGR amount increase so that the value becomes atmospheric pressure and the required internal EGR amount can be secured. The opening speed of the solenoid valve 2 at is set slower.

Note that, during the opening period of the intake valve 4, the solenoid valve downstream portion 2a and the in-cylinder space 1a are electrically connected, and the pressure in the in-cylinder space 1a at the intake TDC also becomes the pressure value at the point P_e3.
This reduces the difference between the pressure in the cylinder internal space 1a and the atmospheric pressure (the pressure in the space on the crankshaft 9a side across the piston 9b) when the piston 9b descends from the intake TDC, as in the case of low load. In this way, pump loss can be reduced.
Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a.

  However, if the opening speed of the solenoid valve 2 is set too late in the period from the opening timing of the solenoid valve 2 to the intake TDC in an attempt to further increase the amount of burnt gas blown back to the solenoid valve downstream portion 2a, the intake TDC The opening area S of the solenoid valve 2 is reduced.

As a result, in the first half of the intake stroke, since the opening area S of the solenoid valve 2 is small, intake resistance at the solenoid valve 2 increases, which may adversely affect fuel consumption.
Since the pressure value at the point P_e1 increases as the load increases, air flows from the surge tank 7 to the solenoid valve downstream portion 2a via the solenoid valve 2 during the period from the opening timing of the solenoid valve 2 to the intake TDC. Even if this is suppressed, if the load becomes very large, the required internal EGR amount cannot be secured.
For the above reason, in the operation region where the load is very large, the required internal EGR amount may not be ensured even by the second embodiment of the present invention.

Next, the relationship between the load and the internal EGR according to the second embodiment of the present invention will be described with reference to FIG. In FIG. 6, an internal EGR amount characteristic L (one-dot chain line) indicates an internal EGR amount according to the second embodiment of the present invention.
According to the internal EGR amount characteristic L according to the second embodiment of the present invention, the internal EGR amount increases as the load increases, and the internal EGR amount decreases from a region where the load increases to some extent.

On the other hand, according to the internal EGR amount characteristic J (two-dot chain line) of the conventional apparatus, as described above, the internal EGR amount decreases as the load increases, and thus the difference from the required internal EGR amount H increases.
Therefore, according to the second embodiment of the present invention, even when the load is large, a larger amount of internal EGR can be ensured than in the case of the conventional device.

However, the second embodiment of the present invention is slightly different from the first embodiment in the following points.
That is, in the above-described first embodiment, when the load increases, the opening timing of the solenoid valve 2 is controlled more retarded than the closing timing IVC of the intake valve 4.
On the other hand, in the second embodiment of the present invention, even when the load is large, the solenoid valve 2 is opened from the time before the opening timing IVO of the intake valve 4 and the solenoid valve downstream portion 2a is more or less opened. Air flows in.
Therefore, according to the second embodiment of the present invention, the amount of internal EGR that can be secured is slightly smaller at the time of high load than in the case of the first embodiment.

  By the way, regarding the pump loss, also in the second embodiment of the present invention, the pressure in the cylinder space 1a at the intake TDC is the atmospheric pressure and flows into the downstream portion of the throttle valve according to the required intake air amount. Since the throttle valve is closed at the time, the pump loss can be reduced as in the case of the conventional device (Patent Document 1).

  Further, as described above, the required internal EGR amount when the load on the internal combustion engine is the same is smaller when the internal combustion engine is cold than when the internal combustion engine is warm, but from the opening timing of the solenoid valve 2 when the internal combustion engine is cold. Corresponding by setting the opening speed of the solenoid valve 2 during the period up to the intake TDC faster than when warming up, and reducing the amount of burnt gas blown back to the solenoid downstream portion 2a when cooling down than when warming up. Can do.

  Incidentally, the solenoid valve control map in the control unit 11 sets the opening timing, closing timing, opening speed and closing speed of the solenoid valve 2 in accordance with the value of the required intake air amount for each engine rotation speed. The value is obtained from the engine speed according to each engine rotation speed and the above contents.

As described above, the intake control valve control means 23 in the control unit 11 of the internal combustion engine control apparatus according to the second embodiment of the present invention operates according to the opening speed of the intake control valve (solenoid valve 2). The solenoid valve 2 is opened after the closing timing, and the solenoid valve 2 is closed by the next closing timing of the intake valve 4.
That is, the intake control valve control means 23 determines the opening speed of the solenoid valve 2 during the period from the opening timing of the solenoid valve 2 to the intake TDC according to the required intake air amount and the required internal EGR amount.

Thereby, even if the response speed of opening and closing of the solenoid valve 2 is slow and the engine is in a high load operation state, the required internal EGR amount can be ensured and the pump loss can be reduced.
As a result, it is possible to provide an internal combustion engine control device that achieves improved fuel efficiency and reduced NOx emissions.

The intake control valve control means 23 sets the opening speed of the solenoid valve 2 slower as the required intake air amount increases, and sets the opening speed of the solenoid valve 2 slower as the required internal EGR amount increases.
Specifically, as the load increases and the required intake air amount and the required internal EGR amount increase, the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC is set slower, The opening speed of the solenoid valve 2 at the time of high load is set slower than that at the time of low load.

  As a result, an increase in the pressure P of the solenoid valve downstream portion 2a during the closing period of the intake valve 4 is suppressed, and the air flow to the solenoid valve downstream portion 2a during the period from the opening timing IVO of the intake valve 4 to the intake TDC is suppressed. Inflow can be suppressed, and the amount of burnt gas that blows back to the solenoid valve downstream portion 2a can be increased.

Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a, and in the intake TDC, the solenoid valve downstream portion by the blow back of the already burned gas and the inflow of air. As the load increases and the required intake air amount and the required internal EGR amount increase so that 2a becomes atmospheric pressure, the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC is set slower. To do.
Thereby, even if the load is large, the required internal EGR amount can be secured and the pump loss can be reduced.

  Even if the required internal EGR amount changes without changing the load, the opening speed of the solenoid valve 2 during the period from the opening timing of the solenoid valve 2 to the intake TDC decreases as the required internal EGR amount increases. By setting later than the time of load, the amount of burnt gas that blows back to the solenoid valve downstream portion 2a can be increased.

Further, the required internal EGR amount can be secured by the already burned gas blown back to the solenoid valve downstream portion 2a, and in the intake TDC, the solenoid valve downstream portion by the blow back of the already burned gas and the inflow of air. As the required internal EGR amount increases, the opening speed of the solenoid valve 2 in the period from the opening timing of the solenoid valve 2 to the intake TDC is set slower so that 2a becomes atmospheric pressure.
Thereby, even if the required internal EGR amount increases without changing the load, the required internal EGR amount can be secured and the pump loss can be reduced.

  In the second embodiment, the case where the solenoid valve 2 is used as the intake control valve has been described as an example. However, the present invention is not limited thereto, and for example, a throttle valve that can be opened and closed at high speed may be used.

1 is a block configuration diagram showing an internal combustion engine control apparatus according to Embodiment 1 of the present invention. FIG. It is a functional block diagram which shows the control unit which concerns on Embodiment 1 of this invention. It is an enlarged view which shows the specific structure of the solenoid valve in FIG. 1, (a) is a sectional side view, (b) is sectional drawing by the A-A 'line in (a). It is explanatory drawing which shows the relationship between the opening area of a solenoid valve at the time of applying Embodiment 1 of this invention, and a crank angle. It is explanatory drawing which shows the relationship between the pressure of the solenoid valve downstream part at the time of applying Embodiment 1 of this invention, and a crank angle. It is explanatory drawing which shows the relationship between the load at the time of applying Embodiment 1, 2 of this invention and internal EGR amount with a general internal EGR amount characteristic. It is a figure which shows the relationship between the opening area of a solenoid valve at the time of applying Embodiment 2 of this invention, and a crank angle. It is a figure which shows the relationship between the solenoid valve downstream part at the time of applying Embodiment 2 of this invention, and a crank angle.

Explanation of symbols

  1 cylinder, 1a cylinder internal space (combustion space), 2 solenoid valve (intake control valve), 2a solenoid valve downstream, 3 fuel injection valve, 4 intake valve, 5 exhaust valve, 6 spark plug, 8 air flow sensor, 9a crank Axis, 10 Crank angle sensor, 11 Control unit, 16 Intake pipe, 18 Water temperature sensor, 20 Various sensors, 21 Required intake amount determination means, 22 Required internal EGR amount determination means, 23 Intake control valve control means, A to E Intake control Valve opening / closing characteristics, VC exhaust valve closing timing, IVO intake valve opening timing, IVC intake valve closing timing, K, L internal EGR amount characteristics, P solenoid valve downstream pressure, P_a to P_e solenoid valve downstream timing Pressure characteristics, S Intake control valve opening area, θ Crank angle.

Claims (6)

In an internal combustion engine controller for controlling an internal combustion engine having one or more cylinders having an intake valve and an exhaust valve,
Various sensors for detecting the operating state of the internal combustion engine;
An intake control valve that is provided in an intake pipe in the vicinity of the intake valve and controls the amount of intake air flowing into the cylinder;
A control unit that controls opening and closing of the intake control valve according to the operating state,
The control unit is
Required intake air amount determining means for determining a required intake air amount required in accordance with the operating state;
Requested internal EGR amount determining means for determining a requested internal EGR amount required in accordance with the operating state;
Intake control valve control means for determining the opening timing of the intake control valve based on the required intake air amount and the required internal EGR amount;
The intake control valve control means opens the intake control valve after the closing timing of the intake valve according to the opening timing of the intake control valve, and keeps the intake control valve by the next closing timing of the intake valve. An internal combustion engine control device that is closed.   The internal combustion engine control device according to claim 1, wherein the intake control valve control means retards the opening timing of the intake control valve as the required intake air amount increases.   The internal combustion engine control device according to claim 1 or 2, wherein the intake control valve control means retards the opening timing of the intake control valve as the required internal EGR amount increases. In an internal combustion engine controller for controlling an internal combustion engine having one or more cylinders having an intake valve and an exhaust valve,
Various sensors for detecting the operating state of the internal combustion engine;
An intake control valve that is provided in an intake pipe in the vicinity of the intake valve and controls the amount of intake air flowing into the cylinder;
A control unit that controls the opening and closing of the intake control valve according to the operating state,
The control unit is
Required intake air amount determining means for determining a required intake air amount required in accordance with the operating state;
Requested internal EGR amount determining means for determining a requested internal EGR amount required in accordance with the operating state;
Intake control valve control means for determining an opening speed of the intake control valve based on the required intake air amount and the required internal EGR amount;
The intake control valve control means opens the intake control valve after the closing timing of the intake valve according to the opening speed of the intake control valve, and opens the intake control valve by the next closing timing of the intake valve. An internal combustion engine control device that is closed.   The internal combustion engine control device according to claim 4, wherein the intake control valve control means sets the opening speed of the intake control valve to be slower as the required intake air amount increases.   The internal combustion engine controller according to claim 4 or 5, wherein the intake control valve control means sets the opening speed of the intake control valve to be slower as the required internal EGR amount increases.

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