JPH10176558A - Engine operation control device - Google Patents

Abstract

(57) [Problem] To provide an engine operation control device capable of improving a scavenging effect by a negative pressure wave of exhaust pulsation to increase an intake air amount and improving fuel efficiency. A variable intake timing mechanism for variably controlling the opening / closing timing of an intake valve, a variable exhaust timing mechanism for variably controlling the opening / closing timing of an exhaust valve,
A variable mechanism control means for controlling the opening and closing timing of the intake valve and the exhaust valve by the exhaust timing variable mechanisms according to the operating state of the engine; Is that the center time of the overlap period O / L in which both the intake valve 2 and the exhaust valve 3 are open is at the top dead center (TDC) in the low-speed rotation low-load operation range (the operation range A in FIG. 1) of the engine. Roughly match,
In most of the remaining operation range (the operation ranges B1 to B4 in FIG. 1), the intake and exhaust timing variable mechanisms 6 and 7 are controlled so as to be after the top dead center (ATDC).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device which variably controls the intake valve opening / closing timing and the exhaust valve opening / closing timing according to the operating state of an engine.

[0002]

2. Description of the Related Art Conventionally, as an operation control device for an engine,
Some include a variable intake timing mechanism for changing the opening / closing timing of the intake valve, and variable mechanism control means for controlling the opening / closing timing of the intake valve by the variable intake timing mechanism in accordance with the operating state of the engine.

In this conventional apparatus, in the low-medium-speed rotation range of the engine, the opening and closing timing of the intake valve is advanced to make the intake valve so-called prematurely closed, thereby reducing the pushback of the intake air and increasing the low-medium-speed torque. Also, increasing the overlap to increase the internal EGR and improve the fuel efficiency has been performed.

[0004]

However, in the conventional operation control device described above, even if the opening and closing timing of the intake valve is advanced to close it early to reduce the pushback of intake air, the positive pressure wave of exhaust pulsation causes the opening of the intake valve to open. In the region that reaches the exhaust port during the period, the scavenging effect is low, the intake air amount does not increase, and the torque cannot be improved. Further, even if the internal EGR is increased, fuel efficiency cannot be improved as compared with the external EGR.

The present invention has been made in view of the above-mentioned conventional problems, and provides an engine operation control device capable of improving a scavenging effect by a negative pressure wave of exhaust pulsation to increase an intake air amount and improving fuel efficiency. That is the task.

[0006]

A first aspect of the present invention is a variable intake timing mechanism for variably controlling the opening and closing timing of an intake valve, a variable exhaust timing mechanism for variably controlling the opening and closing timing of an exhaust valve, and intake and exhaust timings. An engine operation control device comprising: a variable mechanism control means for controlling opening / closing timing of an intake valve and an exhaust valve by a variable mechanism in accordance with an operation state of the engine; wherein the variable mechanism control means includes both an intake valve and an exhaust valve. The center time of the overlap period in which is open substantially coincides with the top dead center (TDC) in the low-speed rotation low-load operation range (the operation range A in FIG. 1) of the engine,
In most of the remaining operation range (the operation ranges B1 to B4 in FIG. 1), the variable intake / exhaust timing mechanism is controlled so as to be after the top dead center (ATDC).

According to a second aspect of the present invention, in the first aspect, the variable mechanism control means determines that the center timing of the overlap period is before the top dead center (BTDC) in a part of the remaining operating ranges B1 to B4. The variable intake / exhaust timing mechanism is controlled in such a manner as to achieve this.

According to a third aspect of the present invention, in the first aspect, most of the remaining operation range includes a low-medium-speed rotation low-medium-load operation range (the operation range B1 in FIG. 1) and a high-speed rotation low-medium-load operation. It is characterized in that it is a region (operation region B3 in FIG. 1).

A fourth aspect of the present invention is characterized in that, in the second aspect, the part of the remaining operating range is a low-medium-speed rotation high-load operating range (an operating range B2 in FIG. 1).

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the variable mechanism control means is provided when the operating range of the engine is divided into A and B1 to B4 as shown in FIG. The variable intake / exhaust timing mechanism is controlled so that the center time of the lap period is as follows in each operation range.

A (low speed rotation, low load operation range): The above-mentioned center is obtained by minimizing the amount of advance of the intake valve opening timing (most retarded) and minimizing the amount of retard of the exhaust valve closing timing (most advanced). The timing is almost matched with TDC. B1 (low-medium-speed rotation / low-medium load operation range): The central timing is set to ATDC by increasing the amount of advance of the intake valve opening timing and increasing the amount of retard of the exhaust valve closing timing. B2 (low-medium-speed high-load operation range): The central timing is set to BTDC to approximately by making the amount of advance of the intake valve opening timing variable and the amount of retard of the exhaust valve closing timing variable from small to large. Variable between TDCs. B3 (high-speed low-medium load operation range): The central timing is set to ATDC by increasing the amount of advance of the intake valve opening timing to the minimum (most retarded) and increasing the amount of retard of the exhaust valve closing timing. B4 (High-speed rotation high-load operation range): The central timing is set substantially to TDC by reducing the amount of advance of the intake valve opening timing and the amount of retardation of the exhaust valve closing timing.

According to a sixth aspect of the present invention, there is provided an exhaust control valve according to any one of the first to fifth aspects, wherein the exhaust control valve variably controls a substantial exhaust passage length, and the substantial exhaust passage length by the exhaust control valve is set to an operating state of the engine. Exhaust control valve control means for controlling the exhaust control valve so that the negative pressure wave due to exhaust pulsation has a substantial exhaust path length reaching the exhaust port at the time of the overlap. It is characterized by doing.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 4 are diagrams for explaining an engine operation control device according to an embodiment of the present invention, and FIGS. 1 and 2 are for explaining the configuration and control operation of the embodiment device. FIG. 3 is a schematic diagram showing the opening / closing timing of an intake valve and an exhaust valve, and an overlap state, and FIG. 4 is a schematic overall configuration diagram of the apparatus of this embodiment.

In FIG. 1, reference numeral 1 denotes a water-cooled 4-cycle, 4-cylinder, 4-valve engine. The engine 1 includes intake valves 2 and 2 for opening and closing two intake ports for each cylinder, and exhaust valves 3 for opening and closing exhaust ports. , 3 are provided. The intake valve 2 and the exhaust valve 3 are opened and closed by an intake cam shaft 4 and an exhaust cam shaft 5, respectively. The intake camshaft 4 is provided with an intake timing variable mechanism 6 for variably controlling the opening / closing timing of the intake valve 2, and the exhaust camshaft 5 is provided with an exhaust timing variable mechanism 7 for variably controlling the opening / closing timing of the exhaust valve 3. Has been established.

The variable intake / exhaust timing mechanism is of a type in which the phase angle of the camshaft with respect to the crankshaft is changed in accordance with the operating condition. For example, when the opening timing of the intake valve is advanced by θ, the closing timing is changed. Are also advanced by θ at the same time, and similarly, when the closing timing of the exhaust valve is retarded by θ, the opening timing is also delayed by θ at the same time. Since the specific structure of this type of variable timing mechanism is well known in the art, description thereof will be omitted.
Further, it is of course possible to employ a plurality of cams having different cam nose shapes and adopt a type of variable timing mechanism of selecting one of the cams according to the operation state.

The exhaust device 8 of the engine 1 includes a right manifold 9a for joining exhaust ports of left and right end cylinders.
A left manifold 9b for joining the exhaust ports of the two central cylinders, and the left and right manifolds 9a, 9
and a merging pipe 9 for merging b into one. 9
d is a silencer.

The left and right manifolds 9a, 9b
Is communicated by a communication pipe 9c.
An exhaust control valve 10 that opens and closes the communication pipe 9c is provided at c. The substantial exhaust passage length of the exhaust device 8 becomes “long” when the exhaust control valve 10 is closed, and becomes “short” when the exhaust control valve 10 is opened.

Reference numeral 11 denotes E for controlling the operating state of the engine 1.
The ECU 11 controls the opening / closing timing of the intake valve 2 and the exhaust valve 3 by the intake / exhaust timing variable mechanisms 6 and 7 according to the input engine speed and the engine load (the amount of depression of the accelerator pedal). And a function as exhaust control valve control means for controlling the opening and closing of the communication pipe 9c by the exhaust control valve 10.

The variable mechanism control function of the ECU 11 determines the opening timing of the intake valve 2 and the closing timing of the exhaust valve 3 based on the engine speed and load with reference to a low-speed low-load operation range (idle rotation range). In order to improve the engine torque, reduce the fuel consumption, improve the properties of the exhaust gas, and further reduce the temperature of the exhaust gas, the control is performed on the advance side and the retard side, respectively.

The exhaust control valve control function of the ECU 11 controls the opening and closing of the exhaust control valve 10 so that the negative pressure wave due to the exhaust pulsation has a substantial exhaust path length reaching the exhaust port when the intake valve and the exhaust valve overlap. Usually, the exhaust control valve 10 changes the substantial exhaust passage length in two stages, and it is difficult to always tune the negative pressure wave to the exhaust port at the time of overlap with the engine speed in each stage. However, in the present embodiment, the tuning is accurately realized at each engine speed by changing the closing timing of the exhaust valve 3.

Next, the operation and effect of this embodiment will be described. In the present embodiment, the opening / closing timing of the intake valve 2 and the exhaust valve 3 is variably controlled in accordance with the operation state of the engine. In particular, the size of the overlap where both the intake valve 2 and the exhaust valve 3 are both open and The center timing is variably controlled between before top dead center (BTDC) and after top dead center (ATDC), and the exhaust control valve 10 is controlled so that the negative pressure wave of exhaust pulsation reaches the exhaust port at the time of the above overlap. Is done.

First, regarding the control of the magnitude of the overlap and the position of the center timing, the operating range of the engine is divided into A, B1 to B4 as shown in FIG. Is done.

A (low-speed rotation, low-load operation range): the advance amount of the intake valve opening timing is minimized (see b1 late opening in FIG. 3), and the retard amount of the exhaust valve closing timing is minimized (b1 'early in the figure). As shown by a broken line in FIG. 3, the center timing of the overlap is made to substantially coincide with TDC (top dead center). It should be noted that the advance amount and the retard amount in the operation range A are set as the control standards (see A (idling) in FIG. 1).

B1 (low-medium-speed low-medium-load operation range): The advance amount of the intake valve opening timing is small (b3), and the retard amount of the exhaust valve closing timing is large (b2 'late closing in the figure). By doing so, the center time is set to ATDC (after top dead center) (FIG. 1
B1).

B2 (low-medium-speed, high-load operation range): The advance amount of the intake valve opening timing is large (b2 opens early in the figure), and the retard amount of the exhaust valve closing timing is small to large (b3'- b2 ′), the center timing is variable between BTDC (before top dead center) and approximately TDC.

Here, in the above-mentioned operation range B2, the reason why the retard amount of the exhaust valve closing timing is changed from small to large is to make the negative pressure wave of the exhaust pulsation reach the exhaust port at the time of overlap.

B3 (high-speed low-medium-load operation range): The central timing is set by setting the advance amount of the intake valve opening timing to the minimum (b1) and the delay amount of the exhaust valve closing timing to the large (b2 '). ATDC.

B4 (high-speed high-load operation range): The central timing is substantially reduced by setting the advance amount of the intake valve opening timing to be small (b3) and the retard amount of the exhaust valve closing timing to be small (b3 '). TDC.

As for the control of the exhaust control valve 10, the operating range of the engine is divided into N1 to N4 based on the engine speed as shown in FIG.
At 2, N3 and N4, the exhaust control valve 10 is closed, opened, closed, and opened, respectively.

As described above, in the present embodiment, in the low-medium-speed high-load operation range (B2), the opening timing of the intake valve 2 is greatly advanced to close it early, and the closing timing of the exhaust valve 3 The amount of retardation is changed from small to large so that the negative pressure wave of exhaust pulsation reaches the exhaust port at the time of overlap, so that the suction back is reduced and the scavenging effect is enhanced by the negative pressure wave of exhaust. ,
It is possible to increase the torque in the low and medium speed rotation range.

Further, a low / medium speed rotation / low / medium load operation range (B1),
In a large part of the engine operating range, that is, both the high-speed and low-medium-load operating range (B3), the center position of the overlap is shifted toward the ATDC side, that is, toward the intake stroke side by greatly delaying the exhaust valve closing timing. Therefore, pumping loss at the start of the intake stroke can be reduced, and fuel efficiency can be improved.

Further, a high-speed rotation low-medium load operation range (B
In 3), since the intake valve 2 is late-closed by minimizing the advance amount of the intake valve opening timing, the actual compression ratio decreases and knocking is avoided, so that the ignition timing can be greatly advanced, and By increasing the retard amount of the exhaust valve closing timing and opening the exhaust valve 3 late, the actual expansion ratio increases, the thermal efficiency can be improved, and the exhaust gas temperature can be reduced.

In this embodiment, the closing timing of the exhaust valve 3 is variably controlled as shown in FIG. 1, and the exhaust control valve 10 is opened and closed as shown in FIGS. In the range, the negative pressure wave due to the exhaust pulsation can be tuned when the intake and exhaust valves overlap,
The scavenging effect is increased, and as shown by the torque curve indicated by the broken line in FIG.

[0034]

As described above, according to the first aspect of the present invention, the center timing of the overlap period in which both the intake valve and the exhaust valve are open is set to the low-speed operation and low-load operation range (A) of the engine. , Almost coincides with the top dead center (TDC), and most of the remaining operating ranges (operating ranges B1 to B4), such as the low-medium-speed and medium-load operating ranges (B1) and Since the opening and closing timings of the intake and exhaust valves were variably controlled so as to be after the top dead center (ATDC) in the high-speed rotation low-medium load operation range (B3), the exhaust valves were closed in most of the operation range. By delaying the timing, the negative pressure wave of the exhaust pulsation can be tuned at the time of overlap in most of the operating range, and the scavenging effect can be enhanced to increase the intake air amount and increase the torque.

Further, by making the overlap closer to ATDC, that is, closer to the intake stroke side, there is an effect that pumping loss in the intake stroke is reduced and fuel efficiency can be improved.

Further, since the intake valve is closed late, the actual compression ratio is reduced and knocking is avoided, so that the ignition timing can be advanced greatly, and the retard amount of the exhaust valve closing timing can be increased. By opening the exhaust valve late, the actual expansion ratio is increased, the thermal efficiency can be improved, and the exhaust gas temperature can be reduced.

According to the second aspect of the present invention, the central timing of the overlap period is set to a part of the remaining operating ranges B1 to B4, for example, a low-to-medium-speed high-load operating range (B2 In), the opening and closing timings of the intake valve and the exhaust valve are variably controlled so as to be before the top dead center (BTDC). Therefore, in this part of the operating range, the intake valve closes prematurely, and the pushback of intake air is reduced. Therefore, there is an effect that the torque can be improved by increasing the intake air amount.

According to the fifth aspect of the present invention, the central timing of the overlap is set at TDC in the low-speed rotation low-load operation range A.
And ATD in the low-medium-speed mid-load operation range B1.
C, variable between BTDC and approximately TDC in the low-medium-speed high-load operation region B2, ATDC in the high-speed rotation low-medium-load operation region B3, and approximately TD in the high-speed rotation high-load operation region B4.
C, the torque can be increased by increasing the amount of intake air, the pumping loss in the intake stroke can be reduced, fuel efficiency can be improved, and the thermal efficiency can be improved and the exhaust gas temperature can be reduced. The effect that can be achieved can be specifically realized.

According to the sixth aspect of the present invention, the center position of the overlap is determined by the BTDC according to the operating state of the engine.
To ATDC, and the exhaust control valve controls the substantial exhaust passage length so that the negative pressure wave due to exhaust pulsation reaches the exhaust port at the time of the above overlap. Negative pressure waves due to pulsation can be tuned when the intake and exhaust valves overlap, thereby improving the scavenging efficiency and increasing the amount of intake air, and has the effect of improving the torque especially in the low to middle speed range.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the configuration and operation of an engine operation control device according to an embodiment of the present invention;

FIG. 2 is a diagram for explaining the configuration and operation of the operation control device.

FIG. 3 is a view for explaining the opening / closing timing of intake and exhaust valves and the overlapping state of the operation control device.

FIG. 4 is a schematic diagram showing an overall configuration of the operation control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake valve 3 Exhaust valve 6 Intake timing variable mechanism 7 Exhaust timing variable mechanism 10 Exhaust control valve 11 ECU (variable mechanism control means, exhaust control valve control means) A Low speed low load operation range B1 Low middle speed load Operating range B2 Low-medium-speed high-load operation range B3 High-speed low-medium-load operation range B4 High-speed rotation high-load operation range ATDC After top dead center BTDC Before top dead center TDC Top dead center O / L Overlap period

Claims (6)

[Claims] 1. A variable intake timing mechanism for variably controlling the opening and closing timing of an intake valve, a variable exhaust timing mechanism for variably controlling the opening and closing timing of an exhaust valve, and an opening and closing timing of an intake valve and an exhaust valve by a variable intake and exhaust timing mechanism. And a variable mechanism control means for controlling the variable mechanism control means in accordance with the operation state of the engine. In the low-speed and low-load operation range of the engine (the operation range A in FIG. 1), it almost coincides with the top dead center (TDC), and the remaining operation range (the operation range B in FIG. 1).
An operation control device for an engine, wherein the intake / exhaust timing variable mechanism is controlled so that most of 1 to B4) is after the top dead center (ATDC). 2. The variable mechanism control means according to claim 1, wherein the central timing of the overlap period is set at a position before the top dead center (BTD) in a part of the remaining operating ranges B1 to B4.
An operation control device for an engine, wherein the variable intake / exhaust timing mechanism is controlled so as to satisfy C). 3. The operation range according to claim 1, wherein most of the remaining operation range includes a low-medium-speed rotation low-medium-load operation range (operation range B1 in FIG. 1) and a high-speed rotation low-medium-load operation range (FIG. Operating range B
3) An operation control device for an engine, wherein 4. The operation range according to claim 2, wherein the part of the remaining operation range is a low-medium-speed rotation high-load operation range (the operation range B in FIG. 1).
2) An operation control device for an engine, wherein 5. The variable timing control device according to claim 1, wherein the variable mechanism control means is configured to divide the operating range of the engine into A and B1 to B4 as shown in FIG. Controlling the intake and exhaust timing variable mechanism in each operation range as follows. A (low-speed rotation low-load operation range): The central timing is set by setting the advance amount of the intake valve opening timing to the minimum (most retarded) and the exhaust valve closing timing to the minimum (most advanced angle). TD
Substantially match C. B1 (low-medium-speed rotation / low-medium load operation range): The central timing is set to ATDC by increasing the amount of advance of the intake valve opening timing and increasing the amount of retard of the exhaust valve closing timing. B2 (low-medium-speed high-load operation range): The central timing is set to BTDC to approximately by making the amount of advance of the intake valve opening timing variable and the amount of retard of the exhaust valve closing timing variable from small to large. Variable between TDCs. B3 (high-speed low-medium load operation range): The central timing is set to ATDC by increasing the amount of advance of the intake valve opening timing to the minimum (most retarded) and increasing the amount of retard of the exhaust valve closing timing. B4 (High-speed rotation high-load operation range): The central timing is set substantially to TDC by reducing the amount of advance of the intake valve opening timing and the amount of retardation of the exhaust valve closing timing. 6. An exhaust control valve according to claim 1, wherein said exhaust control valve variably controls a substantial exhaust passage length, and the substantial exhaust passage length by said exhaust control valve is controlled in accordance with an operation state of the engine. Exhaust control valve control means, wherein the exhaust control valve control means controls the exhaust control valve so that a negative pressure wave due to exhaust pulsation has a substantial exhaust path length reaching the exhaust port at the time of the overlap. Engine operation control device.