JP3678861B2 - Engine operation control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an operation control device that variably controls an intake valve opening / closing timing and an exhaust valve opening / closing timing in accordance with an operating state of an engine.
[0002]
[Prior art]
As an engine operation control device, conventionally, an intake timing variable mechanism that changes the opening / closing timing of an intake valve, and a variable mechanism control means that controls the opening / closing timing of the intake valve by the intake timing variable mechanism according to the operating state of the engine. There is something to prepare.
[0003]
In this conventional device, in the low and medium speed rotation range of the engine, by opening and closing the intake valve, the intake valve is closed so that the intake push-back is reduced and the low and medium speed torque is increased. Increasing the lap to increase the internal EGR and improving fuel efficiency is being carried out.
[0004]
[Problems to be solved by the invention]
However, in the above conventional operation control device, even if the intake valve opening / closing timing is advanced to quickly close and the push back of the intake is reduced, the positive pressure wave of the exhaust pulsation reaches the exhaust port during the intake valve open period. The scavenging effect is low, the amount of intake air does not increase, and the torque cannot be improved. Further, even if the internal EGR is increased, the fuel efficiency cannot be improved as compared with the external EGR.
[0005]
The present invention has been made in view of the above-described conventional problems, and it is an object of the present invention to provide an engine operation control apparatus that can improve the scavenging effect by the negative pressure wave of the exhaust pulsation to increase the intake air amount and improve the fuel consumption. It is said.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided an intake timing variable mechanism for variably controlling the opening / closing timing of the intake valve, an exhaust timing variable mechanism for variably controlling the opening / closing timing of the exhaust valve, and an intake valve and an exhaust valve by the intake / exhaust timing variable mechanism. An engine operation control device comprising variable mechanism control means for controlling the opening / closing timing in accordance with the engine operating state, wherein the variable mechanism control means is a center of an overlap period in which both the intake valve and the exhaust valve are open. The timing is substantially the same as the top dead center (TDC) in the low-speed rotation and low-load operation region of the engine (operation region A in FIG. 1), and in most of the remaining operation regions (operation regions B1 to B4 in FIG. 1). , after top dead center (ATDC) becomes, in the remaining are part of the operating range low and medium speed rotation and high-load operating range (operating range B2 in FIG. 1), the advance amount of the intake valve opening timing Large, variable and so as the intake between the top dead center (BTDC) - substantially top-dead-center (TDC) by varying the retard amount of the exhaust valve closing timing between the small-sized, the exhaust timing adjustment It is characterized by controlling the mechanism.
[0007]
Delete [0008]
According to a second aspect of the present invention, in the first aspect of the present invention, 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. 1 operating region B3).
It is characterized by.
[0010]
According to a third aspect of the present invention, there is provided an intake timing variable mechanism for variably controlling the opening / closing timing of the intake valve, an exhaust timing variable mechanism for variably controlling the opening / closing timing of the exhaust valve, and an intake valve and an exhaust valve by the intake / exhaust timing variable mechanism. In the engine operation control device comprising the variable mechanism control means for controlling the opening / closing timing according to the engine operating state, the variable mechanism control means is provided when the engine operating range is divided into A and B1 to B4. The intake and exhaust timing variable mechanism is controlled so that the center time of the overlap period is as follows in each operation region.
[0011]
A (low speed rotation and low load operation range): The above-mentioned central timing is set to TDC by setting the advance amount of the intake valve opening timing to the minimum (most retarded angle) and the retard amount of the exhaust valve closing timing to the minimum (most advanced angle). To approximately match.
B1 (low / medium speed rotation / low / medium load operation region): The above-mentioned central timing is set to ATDC by increasing the advance amount of the intake valve opening timing and increasing the retard amount of the exhaust valve closing timing.
B2 (low / medium speed rotation / high load operation region): By making the advance amount of the intake valve opening timing large and the delay amount of the exhaust valve closing timing variable between small and large, the above central timing is set to BTDC. It is variable between TDCs.
B3 (high-speed rotation low and medium load operation region): The central timing is set to ATDC by minimizing the advance amount of the intake valve opening timing (most retarded angle) and increasing the retard amount of the exhaust valve closing timing.
B4 (High-speed rotation high load operation region): The above-mentioned central timing is made substantially TDC by making the advance amount of the intake valve opening timing small and making the delay amount of the exhaust valve close timing small.
[0012]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the exhaust control valve that variably controls the substantial exhaust passage length, and the substantial exhaust passage length by the exhaust control valve is determined according to the operating state of the engine. An exhaust control valve control means for controlling, and the exhaust control valve control means controls the exhaust control valve so that a negative pressure wave due to exhaust pulsation becomes a substantial exhaust passage length reaching the exhaust port at the time of the overlap. It is a feature.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 to 4 are diagrams for explaining an engine operation control apparatus according to an embodiment of the invention of claims 1 to 4 , and FIGS. 1 and 2 are for explaining the configuration and control operation of the embodiment apparatus. FIG. 3 is a schematic diagram showing the opening and closing timings of the intake and exhaust valves and the overlap state, and FIG. 4 is a schematic overall configuration diagram of the apparatus of the present embodiment.
[0014]
In the figure, 1 is a water-cooled four-cycle four-cylinder four-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 and 3 for opening and closing an exhaust port. It has. The intake valves 2 and the exhaust valves 3 are driven to open and close by the intake cam shaft 4 and the 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. It is installed.
[0015]
The intake / exhaust timing variable mechanism is of a type that changes the phase angle of the camshaft with respect to the crankshaft according to the operating state. For example, if the opening timing of the intake valve is advanced by θ, the closing timing is simultaneously θ Similarly, when the exhaust valve closing timing is retarded by θ, the opening timing is also retarded by θ at the same time. The specific structure of this type of variable timing mechanism is well known in the art and will not be described. Of course, it is also possible to employ a timing variable mechanism of a type in which a plurality of cams having different cam nose shapes are provided and any one of the cams is selected according to the operating state.
[0016]
The exhaust system 8 of the engine 1 includes a right manifold 9a for joining the exhaust ports of the 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, And a joining pipe 9 for joining 9b into one. In addition, 9d is a silencer.
[0017]
The middle portions of the left and right manifolds 9a and 9b are communicated with a communication pipe 9c, and an exhaust control valve 10 for opening and closing the communication pipe 9c is provided in the communication pipe 9c. The substantial exhaust passage length of the exhaust device 8 becomes “long” when the exhaust control valve 10 is closed and becomes “short” when it is opened.
[0018]
Reference numeral 11 denotes an ECU that controls the operating state of the engine 1. The ECU 11 controls the intake valves by the intake and exhaust timing variable mechanisms 6 and 7 according to the input engine speed and engine load (accelerator pedal depression amount). 2. A function as variable mechanism control means for controlling the opening / closing timing of the exhaust valve 3 and a function as exhaust control valve control means for controlling the opening / closing of the communication pipe 9c by the exhaust control valve 10 are provided.
[0019]
The variable mechanism control function by the ECU 11 is based on the engine torque based on the engine speed and the load, with the opening timing of the intake valve 2 and the closing timing of the exhaust valve 3 being based on the low speed rotation and low load operation range (idle rotation range). From the standpoints of improving fuel efficiency, reducing fuel consumption, improving exhaust gas properties, and further reducing exhaust gas temperature, control is made on the advance side and retard side, respectively.
[0020]
The exhaust control valve control function of the ECU 11 controls the opening and closing of the exhaust control valve 10 so that a negative pressure wave due to exhaust pulsation becomes a substantial exhaust passage length reaching the exhaust port when the intake valve and the exhaust valve overlap. Normally, the exhaust control valve 10 changes the substantial exhaust passage length in two stages, and it is not always easy to tune the negative pressure wave to reach the exhaust port at the time of overlap with the engine speed of each stage. However, in this embodiment, the above-described tuning is realized with high accuracy at each engine speed by changing the closing timing of the exhaust valve 3.
[0021]
Next, the function and effect of the present embodiment device will be described.
In the present embodiment, the opening / closing timing of the intake valve 2 and the exhaust valve 3 is variably controlled according to the operating state of the engine, and in particular, the size of the overlap where both the intake valve 2 and the exhaust valve 3 are open and The central 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 the exhaust pulsation reaches the exhaust port at the time of the overlap. Is done.
[0022]
First, regarding the control of the size of the overlap and the position of the central time, the engine operating range is divided into A, B1 to B4 as shown in FIG. 1, and the following control is performed for each operating range.
[0023]
A (low speed rotation and low load operation range): The advance amount of the intake valve opening timing is minimized (see b1 slow opening in FIG. 3), and the retard amount of the exhaust valve closing timing is minimized (see b1 ′ early closing in the same figure). By doing so, as shown by a broken line in FIG. 3, the center time of the overlap is made substantially coincident with TDC (top dead center). Note that the advance amount and retard amount in this operation area A are used as control standards (see A (idling) in FIG. 1).
[0024]
B1 (low / medium speed rotation / low / medium load operation region): By making the advance amount of the intake valve opening timing small (b3) and the delay amount of the exhaust valve closing timing being large (b2 'delay closing in the figure) The central time is assumed to be ATDC (after top dead center) (see B1 in FIG. 1).
[0025]
B2 (low / medium-speed rotation / high-load operation range): The advance amount of the intake valve opening timing is large (b2 early opening in the figure), and the retard amount of the exhaust valve closing timing is small to large (b3 ′ to b2 ′). The center time is made variable between BTDC (before top dead center) and approximately TDC.
[0026]
Here, the reason why the retard amount of the exhaust valve closing timing is changed from small to large in the operating range B2 is to allow the negative pressure wave of the exhaust pulsation to reach the exhaust port at the time of overlap.
[0027]
B3 (high-speed rotation low / medium load operation range): The advance timing amount of the intake valve opening timing is minimized (b1), and the retardation amount of the exhaust valve closing timing is increased (b2 '), whereby the above-mentioned central timing is set to ATDC. .
[0028]
B4 (High-speed rotation high load operation region): The above-mentioned central timing is set to approximately TDC by setting the advance amount of the intake valve opening timing to a small value (b3) and the delay amount of the exhaust valve closing timing to a small value (b3 '). .
[0029]
Further, with respect to the control of the exhaust control valve 10, the engine operating range is divided into N1 to N4 based on the engine speed as shown in FIG. 2, and the exhaust in each operating range N1, N2, N3, N4. The control valve 10 is closed, opened, closed, and opened, respectively.
[0030]
As described above, in the present embodiment, in the low / medium speed rotation / high load operation region (B2), the intake valve 2 is rapidly closed by greatly advancing the opening timing, and the delay amount of the closing timing of the exhaust valve 3 is set. Since the negative pressure wave of the exhaust pulsation reaches the exhaust port at the time of overlap, the push back of the intake is reduced and the scavenging effect is enhanced by the negative pressure wave of the exhaust. The torque in the high speed range can be increased.
[0031]
Also, in most of the engine operating range, that is, both the low / medium speed rotation / low / medium load operation range (B1) and the high speed rotation / low / medium load operation range (B3), the exhaust valve closing timing is greatly retarded. Since the center position is closer to the ATDC side, that is, closer to the intake stroke side, the pumping loss at the start of the intake stroke can be reduced, and fuel consumption can be improved.
[0032]
Furthermore, in the high-speed rotation low / medium load operation region (B3), the intake valve 2 is closed slowly by minimizing the advance amount of the intake valve opening timing, thereby reducing the actual compression ratio and avoiding knocking. The ignition timing can be greatly advanced, and the exhaust valve closing timing is increased to make the exhaust valve 3 open slowly, thereby increasing the actual expansion ratio and improving the thermal efficiency, and reducing the exhaust gas temperature. it can.
[0033]
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 controlled to be opened and closed as shown in FIGS. 1 and 2. The negative pressure wave due to the exhaust pulsation can be synchronized when the intake and exhaust valves overlap, so that the scavenging effect is increased, and the torque can be improved particularly at low and medium speeds as shown by the broken torque curve in FIG.
[0034]
[Effects of the invention]
As described above, according to the first aspect of the present invention, the central timing of the overlap period in which both the intake valve and the exhaust valve are open is the top dead center (TDC) in the low-speed rotation low load operation region (A) of the engine. ), And most of the remaining operation regions (operation regions B1 to B4), for example, the low / medium-speed rotation / middle load operation region (B1) and the high-speed rotation / low / medium load operation as in the invention of claim 2 In the region (B3), the opening and closing timings of the intake valve and exhaust valve are controlled so that they are after top dead center (ATDC), thereby delaying the closing timing of the exhaust valve in most of the operating range and overlapping Since the center timing is closer to the ATDC side, that is, closer to the intake stroke side, the pumping loss at the intake stroke start timing is reduced, and the fuel consumption can be improved.
[0036]
Further, in the high-speed rotation low / medium load operation region (B3), the intake valve is closed late, so that the actual compression ratio is reduced and knocking is avoided, so that the ignition timing can be greatly advanced, and the exhaust valve is closed. By increasing the timing delay amount and opening the exhaust valve slowly, the actual expansion ratio is increased, so that the thermal efficiency can be improved and the exhaust gas temperature can be reduced.
[0037]
Furthermore , the intake valve is configured so that the central timing of the overlap period can be varied between the top dead center ( BTDC) and the substantially top dead center (TDC) in the low / medium speed high load operation range (B2). opening the exhaust valve, since the variable control of the closing timing, in this part operating region becomes the intake valve closing is quick, Rutotomoni possible to reduce the push-back of intake air, intake air from the increased exhaust effect by the negative pressure wave of the exhaust There is an effect that the torque can be improved by increasing the amount.
[0038]
According to the invention of claim 3 , the center timing of the overlap is made substantially coincident with TDC in the low speed rotation / low load operation area A, and in the low / medium speed rotation / intermediate load operation area B1 and the high speed rotation / low / medium load operation area B3. Since ATDC is used and the exhaust closing timing is reached in most of the operating range, and the center timing of the overlap is closer to the ATDC side , the pumping loss at the start of the intake stroke in the invention of claim 1 is reduced, and the fuel consumption is reduced. The effect of improving the thermal efficiency and reducing the exhaust gas temperature can be specifically realized. In addition, since the variable range between BTDC and substantially TDC is made variable in the low / medium speed rotation / high load operation region B2, the intake valve is quickly closed, the push back of the intake can be reduced, and the exhaust effect is enhanced by the negative pressure wave of the exhaust. Torque can be improved by increasing the amount of intake air.
[0039]
According to a fourth aspect of the present invention, the center position of the overlap is variably controlled between BTDC and ATDC in accordance with the operating state of the engine, and the exhaust pressure control valve substantially reduces the length of the exhaust passage by exhaust pulsation. Controlling the length to reach the exhaust port at the time of overlap, the negative pressure wave due to exhaust pulsation can be synchronized when the intake and exhaust valves overlap in most operating ranges, improving the scavenging efficiency and increasing the intake air The amount can be increased, and there is an effect that the torque can be improved particularly in a low and medium speed rotation region.
[Brief description of the drawings]
1 is a diagram for explaining the structure and operation of the operation control apparatus for an engine according to an embodiment of the present invention of claims 1 to 4.
FIG. 2 is a diagram for explaining the configuration and operation of the operation control device.
FIG. 3 is a view for explaining suction, opening / closing timing of an exhaust valve, and an overlap state of the operation control device.
FIG. 4 is a schematic diagram showing an overall configuration of the operation control apparatus.
[Explanation 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 rotation / low-load operation area B1 Low-medium-speed rotation / intermediate-load operation area B2 Low-medium-speed rotation / high-load operation area B3 High-speed rotation / low / medium-load operation area B4 High-speed rotation / high-load operation area ATDC After top dead center BTDC Before top dead center TDC Top dead center O / L Overlap period

Claims (4)

The intake and output timing variable mechanism that variably controls the opening and closing timing of the intake valve, the exhaust timing variable mechanism that variably controls the opening and closing timing of the exhaust valve, and the opening and closing timing of the intake and exhaust valves by the intake and exhaust timing variable mechanism In the engine operation control device, the variable mechanism control means includes a variable mechanism control means for controlling the low speed rotation of the engine during the overlap period when both the intake valve and the exhaust valve are open. In the low-load operation region (operation region A in FIG. 1), it substantially coincides with the top dead center (TDC), and in most of the remaining operation regions (operation regions B1 to B4 in FIG. 1), after the top dead center (ATDC). ) and, in the remaining operating range portion low and medium speed rotation and high load range which is the (operation range B2 in FIG. 1), the large the advance amount of the intake valve opening timing, exhaust valve closing Thailand Variable and so as the intake between the top dead center (BTDC) - substantially top-dead-center (TDC) by varying the retardation amount ranging between small to large, by controlling the exhaust timing adjustment mechanism An engine operation control device.   In claim 1, the majority of the remaining operating range is a low / medium speed low / medium load operating range (operating range B1 in FIG. 1) and a high speed rotating low / medium load operating range (operating range B3 in FIG. 1). An operation control device for an engine characterized by being. The intake and output timing variable mechanism that variably controls the opening and closing timing of the intake valve, the exhaust timing variable mechanism that variably controls the opening and closing timing of the exhaust valve, and the opening and closing timing of the intake and exhaust valves by the intake and exhaust timing variable mechanism In the engine operation control device having the variable mechanism control means for controlling the engine according to the variable mechanism control means, the variable mechanism control means has a central timing of the overlap period when the engine operating range is divided into A and B1 to B4. An engine operation control apparatus that controls the intake / exhaust timing variable mechanism so as to be as follows in each operation region.
A (low speed rotation and low load operation range): The above-mentioned central timing is set to TDC by setting the advance amount of the intake valve opening timing to the minimum (most retarded angle) and the retard amount of the exhaust valve closing timing to the minimum (most advanced angle). To approximately match.
B1 (low / medium speed rotation / low / medium load operation region): The above-mentioned central timing is set to ATDC by increasing the advance amount of the intake valve opening timing and increasing the retard amount of the exhaust valve closing timing.
B2 (low / medium speed rotation / high load operation region): By making the advance amount of the intake valve opening timing large and the delay amount of the exhaust valve closing timing variable between small and large, the above central timing is set to BTDC. It is variable between TDCs.
B3 (high-speed rotation low and medium load operation region): The central timing is set to ATDC by minimizing the advance amount of the intake valve opening timing (most retarded angle) and increasing the retard amount of the exhaust valve closing timing.
B4 (High-speed rotation high load operation region): The above-mentioned central timing is made substantially TDC by making the advance amount of the intake valve opening timing small and making the delay amount of the exhaust valve close timing small. 4. The exhaust control valve according to claim 1, wherein the exhaust control valve variably controls the substantial exhaust passage length, and the exhaust control valve control means for controlling the substantial exhaust passage length by the exhaust control valve in accordance with the operating state of the engine. And the exhaust control valve control means controls the exhaust control valve so that a negative pressure wave due to exhaust pulsation reaches a substantial exhaust passage length reaching the exhaust port at the time of the overlap. apparatus.

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