JP2011089442A - Fuel injection control device of multicylinder engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device of a multicylinder engine capable of realizing performance suitable for actual travel, by restraining deterioration in engine performance caused by specifications of a cylinder in the whole operation area. <P>SOLUTION: This engine (1) has a low speed specification cylinder by three cylinders and a high speed specification cylinder by three cylinders, and controls respective fuel injection valves (2) so as to respectively inject a fuel injection quantity q1+α increased by a predetermined quantity α to the low speed specification cylinder and a fuel injection quantity q1-α reduced by the predetermined quantity α to the high speed specification cylinder in low speed operation, and controls the respective fuel injection valves so as to respectively inject a fuel injection quantity q2-β reduced by a predetermined quantity β to the low speed specification cylinder and a fuel injection quantity q2+β increased by the predetermined quantity β to the high speed specification cylinder in high speed operation. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for a multi-cylinder engine, and more particularly to fuel injection control for an engine having a plurality of cylinders with different specifications.

2. Description of the Related Art Recently, in a multi-cylinder engine having a plurality of cylinders, there is a combustion control device that controls a fuel injection timing, a fuel supply amount, an injection waveform, an ignition timing, and the like for each cylinder in order to suppress variation in combustion among the cylinders.
For example, in-cylinder pressure of each cylinder is detected so as to suppress variation in torque generated in each cylinder, and fuel ignition timing is controlled according to the in-cylinder pressure, thereby suppressing engine rotation fluctuation and vibration. A technique is known (see Patent Document 1).

JP 2006-152857 A

However, although the technique disclosed in Patent Document 1 can suppress variations in torque generated in each cylinder, it does not optimize combustion for fuel consumption.
Further, even if fuel injection control and ignition control can be performed for each cylinder as in Patent Document 1, the combustion chamber shape, compression ratio, number of injection holes, cone angle, injection hole diameter, swirl ratio, valve timing, etc. Combustion cannot be controlled to the extent caused by the cylinder specifications.

For example, there are engines with cylinders with specifications suitable for low-speed operation (low-speed specifications) and engines with cylinders with specifications compatible with high-speed operation (high-speed specifications). There is a problem that performance deteriorates. Therefore, it cannot always be said that a high-performance driving can be realized in actual driving in which the driving state changes one by one.
The present invention has been made to solve such problems, and the object of the present invention is to suppress deterioration in engine performance due to cylinder specifications in all operating regions and realize performance suitable for actual driving. An object of the present invention is to provide a fuel injection control device for a multi-cylinder engine that can be used.

  In order to achieve the above-described object, in the fuel injection control device for a multi-cylinder engine according to claim 1, a first cylinder having a specification adapted for low speed operation and a second cylinder adapted for high speed operation compared to the first cylinder. An engine having a plurality of cylinders, a fuel supply means provided in each of the cylinders for supplying fuel into the cylinders, and controlling the fuel supply means. The fuel supply amount is increased from the fuel supply amount to the second cylinder, and the fuel supply amount to the second cylinder is increased from the fuel supply amount to the first cylinder during high speed operation. And a control means.

According to a second aspect of the present invention, in the first aspect, the number of cylinders of the first cylinder and the second cylinder is the same, and when the amount of fuel supply to one cylinder is increased, the increase is made to the other cylinder. It is characterized by reducing the fuel supply amount.
A third aspect of the present invention is the first or second aspect, wherein the first cylinder has a specification that the amount of smoke generated is lower than that of the second cylinder during low speed operation, and the second cylinder is the amount of smoke generated during high speed operation. Is characterized by less specifications than the first cylinder.

  In a fourth aspect of the present invention, in the first or second aspect, the first cylinder has a fuel consumption rate lower than that of the second cylinder during low speed operation, and the second cylinder has a fuel consumption rate of the first during high speed operation. It is characterized by a specification lower than that of one cylinder.

According to the fuel injection control device for a multi-cylinder engine of the present invention using the above means, a plurality of cylinders including a first cylinder adapted for low speed operation and a second cylinder adapted for high speed operation are provided. In the engine, the fuel supply means provided in each cylinder is controlled so that the amount of fuel supplied to the first cylinder is increased during low speed operation and the amount of fuel supplied to the second cylinder is increased during high speed operation.
Each cylinder is equipped with a low-speed specification and a high-speed specification, and during the low-speed operation of the engine, the influence of combustion in the first cylinder is increased by increasing the amount of fuel supplied to the first cylinder suitable for low-speed operation. Sometimes, the influence of combustion in the second cylinder can be increased by increasing the amount of fuel supplied to the second cylinder suitable for high-speed operation.

Thus, by increasing the influence degree of the cylinder suitable for the operating state according to the operating state of the engine, it is possible to compensate for the performance deterioration in the cylinder not suitable for the operating state.
As a result, it is possible to suppress the deterioration of the engine performance due to the cylinder specifications in the entire operation region, and to realize the performance suitable for actual traveling.
According to the fuel injection control device for a multi-cylinder engine according to claim 2, the number of cylinders of the first cylinder and the second cylinder is the same, and when increasing the fuel supply amount to one of the cylinders, the increase amount The amount of fuel supplied to the other cylinder is reduced.

In this way, the amount of fuel supplied to one cylinder is increased and the amount of fuel supplied to the other cylinder is reduced, so that the torque output for each cylinder as a whole satisfies the torque required for the engine. Torque fluctuations can be suppressed with easy control.
According to the fuel injection control device for a multi-cylinder engine according to claim 3, regarding the amount of smoke generated, the first cylinder is a cylinder adapted for low speed operation and the second cylinder is adapted for high speed operation.

Thereby, the amount of smoke generated can be suppressed in the entire operation region, and exhaust gas performance suitable for actual traveling can be realized.
According to the fuel injection control apparatus for a multi-cylinder engine of claim 4, regarding the fuel consumption rate (so-called fuel efficiency), the first cylinder is adapted to the low speed operation and the second cylinder is adapted to the high speed operation.
Thereby, deterioration of fuel consumption can be suppressed in the entire driving region, and exhaust fuel consumption performance suitable for actual traveling can be realized.

1 is a schematic overall configuration diagram of an engine including a fuel injection control device according to the present invention. FIG. 5 is a relationship diagram between a fuel injection amount and a smoke generation amount during low-speed operation and high-speed operation of the engine. FIG. 4 is a graph showing the relationship between engine speed and fuel consumption during low-speed operation and high-speed operation of the engine.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Referring to FIG. 1, there is shown a schematic overall configuration diagram of an engine provided with a fuel injection control device according to the present invention.
The engine 1 is an in-line 6-cylinder diesel engine formed in series from the first cylinder # 1 to the sixth cylinder # 6 in order from the front of the vehicle. Each cylinder is provided with a fuel injection valve 2 (fuel supply means), and each fuel injection valve 2 is connected to a common rail 4. Each fuel injection valve 2 is supplied with high-pressure fuel accumulated in the common rail 4 and can inject fuel into the cylinder at an arbitrary injection timing and injection amount. Note that the combustion order is # 1, # 5, # 3, # 6, # 2, and # 4.

Each cylinder of the engine 1 is composed of a group of cylinders having different specifications, and the first cylinder # 1 to the third cylinder # 3 (hereinafter referred to as a low-speed specification cylinder) have specifications suitable for low-speed operation of the engine 1. The fourth cylinder # 4 to the sixth cylinder # 6 (hereinafter referred to as a high-speed specification cylinder) are formed with specifications suitable for high-speed operation of the engine 1 (second cylinder).
Specifically, the low-speed specification cylinder has a high swirl ratio so as to increase the swirl flow in response to the in-cylinder flow weakening due to the low-speed rotation of the engine 1. Further, corresponding to the fact that a sufficient fuel injection period can be obtained when the engine 1 rotates at low speed, the fuel injection valve 2 provided in the low speed cylinder has a small number of nozzle holes, a small nozzle hole diameter, The cone angle is small, and the valve timings of the intake valve and exhaust valve (not shown) are configured so that the valve opening period is short and the overlap is also short. The low-speed cylinder has a small cavity diameter and a deep combustion chamber shape so as to increase fuel consumption (fuel consumption rate) during low-speed operation of the engine 1. In addition, the compression ratio and the like are also set to values suitable for low speed operation of the engine 1.

  On the other hand, in the high-speed specification cylinder, since the intake time is short due to the high-speed rotation of the engine 1, the flow coefficient is more important than the swirl flow, and the swirl ratio is set low so as to weaken the swirl flow. Further, the fuel injection valve 2 provided in the high-speed cylinder has a large number of nozzle holes, a large nozzle hole diameter, and a large cone angle of fuel spray corresponding to a short fuel injection period when the engine 1 rotates at a high speed. The valve timings of the intake valve and the exhaust valve (not shown) are configured such that the valve opening period is long and the overlap is also long. The high-speed cylinder has a shallow combustion chamber shape with a large cavity diameter so that the fuel wall surface adhesion is suppressed even at a high fuel injection pressure and is suitable for high rotation. In addition, the compression ratio and the like are set to values suitable for high-speed operation of the engine 1.

An intake manifold 6 is connected to the intake side of the engine 1, and an intake pipe 8 extends from the intake manifold 6. An air cleaner 10 is provided at the intake upstream end of the intake pipe 8, a compressor 12a of the turbocharger 12 is provided in the middle of the intake pipe 8, and an intercooler 14 is provided downstream of the compressor 12a. Yes.
On the other hand, an exhaust manifold 16 is connected to the exhaust side of the engine 1, and an exhaust pipe 18 extends from the exhaust manifold 16.

The exhaust manifold 16 and the intake manifold 6 are connected to each other by an EGR passage 20 that can return exhaust gas to the intake air as EGR gas. The EGR passage 20 is provided with an EGR cooler 22 that cools the EGR gas and an EGR valve 24 that adjusts the recirculation amount of the EGR gas.
A turbine 12b that is coaxially connected to the compressor 12a is provided in the middle of the exhaust pipe 18.

Further, the output shaft of the engine 1 is connected to a transmission 26, and the transmission 26 shifts the rotational driving force from the engine 1 at a gear ratio according to the transmission gear stage selected by the driver, thereby propeller shaft. 28.
Further, a vehicle equipped with the engine 1 is provided with an ECU 30 (fuel supply control means) as a control device for performing comprehensive control including operation control of the engine 1. The ECU 30 includes a CPU, a memory, a timer counter, and the like, performs various control amount calculations, and controls various devices based on the control amounts.

  For example, on the input side of the ECU 30, various sensors such as a crank angle sensor 32 that detects the crank angle of the engine 1 and an accelerator opening sensor 34 that detects an accelerator opening according to the amount of depression of the accelerator pedal by the driver. It is connected. The ECU 30 can detect the operation state such as the engine speed of the engine 1 and torque required for the engine 1 (hereinafter referred to as required torque) by calculating information from these sensors. . Further, various devices such as the fuel injection valve 2 and the EGR valve 24 of each cylinder are connected to the output side of the ECU 30.

Then, the ECU 30 performs fuel injection control for each of the cylinder groups having the two specifications according to the operating state of the engine 1.
2 and 3, FIG. 2 shows a relationship diagram between the fuel injection amount and the amount of smoke generated during low speed operation and high speed operation of the engine, and FIG. 3 shows low speed operation of the engine. The relationship diagram of the engine speed and fuel consumption at the time and during high-speed operation is shown.

Hereinafter, the fuel injection control performed by the ECU 30 and the effects of the execution of the fuel injection control will be described based on these drawings.
First, the fuel injection control of this embodiment will be described based on the smoke generation amount shown in FIG.
As indicated by the solid lines in FIG. 2 (a), when the engine 1 is operating at low speed, an engine in which all six cylinders are low speed specification cylinders (hereinafter referred to as low speed specification six cylinder engines) is a fuel injection amount. Although the amount of smoke generated is small even if the fuel consumption increases, the amount of smoke generated increases as the fuel injection amount increases in an engine in which all six cylinders are high-speed specification cylinders (hereinafter referred to as a high-speed specification six-cylinder engine). Tend to.

On the other hand, at the time of high speed operation of the engine 1 shown in FIG. 2B, the relationship between the low speed specification 6 cylinder engine and the high speed specification 6 cylinder engine is reversed from the tendency at low speed operation. As the fuel injection amount increases, the amount of smoke generated increases, and the high-speed specification 6-cylinder engine tends to generate less smoke even if the fuel injection amount increases.
2 (a) and 2 (b), the engine 1 including the low-speed specification three cylinders and the high-speed specification three cylinders of the present embodiment has a line segment of the high-speed specification six-cylinder engine and It tends to pass through the middle of a line segment of a low-speed 6-cylinder engine. The tendency of the engine 1 indicated by the alternate long and short dash line indicates a tendency when the required torque is equally distributed to each cylinder and the same fuel injection amount is injected to each cylinder.

  In contrast to the engine 1 that shows the above-described tendency when the same fuel injection amount is injected in each cylinder in the amount of smoke generated, the ECU 30 increases the fuel injection amount to the low-speed specification cylinder and the high-speed specification cylinder during low-speed operation. The fuel injection amount is reduced, and during high-speed operation, the fuel injection amount to the low-speed specification cylinder is reduced and the fuel injection amount to the high-speed specification cylinder is increased. The increase and decrease in the fuel injection amount are set so that the torque output for each cylinder as a whole satisfies the required torque.

Specifically, as shown in FIG. 2A, when the fuel injection amount per cylinder with respect to the required torque of the engine 1 is q1 during low-speed operation, the ECU 30 does not operate for the low-speed specification cylinder. Each fuel injection valve 2 is controlled to inject the fuel injection amount q1 + α increased by the predetermined amount α and the fuel injection amount q1-α decreased by the predetermined amount α for the high speed specification cylinder.
Further, as shown in FIG. 2B, when the fuel injection amount per cylinder with respect to the required torque of the engine 1 is q2 during high-speed operation, the ECU 30 sets a predetermined amount β for the low-speed specification cylinder. Each fuel injection valve is controlled to inject the reduced fuel injection amount q2-β and the fuel injection amount q2 + β increased by a predetermined amount β for the high-speed specification cylinder.

Thus, according to the operating state of the engine 1, the fuel injection amount for the cylinder that is suitable for the operating state is increased, and the fuel injection amount of the other cylinder is decreased by the increased amount. This increases the influence of combustion in the cylinder that is adapted to the operating condition.
That is, in the low speed operation shown in FIG. 2A, as shown by the white circle, the amount of smoke generated when the fuel injection control is performed is the fuel injection amount q1 + α in the low speed 6-cylinder engine. This is an intermediate value a2 between the amount of smoke generated when the fuel is injected and the amount of smoke generated when the fuel injection amount q1-α is injected in the high-speed specification 6-cylinder engine.

In addition, during high-speed operation shown in FIG. 2B, as indicated by white circles, the amount of smoke generated when the fuel injection control is performed is the fuel injection amount q2- in the low-speed 6-cylinder engine. This is an intermediate value b2 between the amount of smoke generated when β is injected and the amount of smoke generated when fuel injection amount q2 + β is injected in a high-speed 6-cylinder engine.
Thereby, in both the low speed operation and the high speed operation, the smoke generation amount is smaller than the smoke generation amounts a1 and b1 when the same fuel injection amounts q1 and q2 are injected into each cylinder, and the smoke performance is improved. The

Next, the fuel injection control of this embodiment will be described based on the fuel consumption shown in FIG.
As indicated by the solid line in FIG. 3, the fuel efficiency of the low-speed specification 6-cylinder engine and the high-speed specification 6-cylinder engine are reversed with respect to a predetermined engine speed. However, the high-speed specification 6-cylinder engine has lower fuel consumption on the high-speed driving side.
As shown by the one-dot chain line in FIG. 3, when the same fuel injection amount is injected into each cylinder in the engine 1 composed of the low-speed specification three cylinders and the high-speed specification three cylinders of this embodiment, It tends to pass through the middle of the line segment of the 6-cylinder engine and the line segment of the low-speed 6-cylinder engine.

  Further, as described above, during low speed operation, by increasing the fuel injection amount to the low speed specification cylinder and decreasing the fuel injection amount to the high speed specification cylinder, the fuel consumption c1 (in the case of injecting the same fuel injection amount for each cylinder) The fuel efficiency is improved to a fuel efficiency c2 (white circle) that is closer to the line segment of the low-speed 6-cylinder engine than the black circle). Even during high-speed operation, by reducing the fuel injection amount to the low-speed specification cylinder and increasing the fuel injection amount to the high-speed specification cylinder, the fuel consumption d1 (black circle mark) when the same fuel injection amount is injected into each cylinder The fuel efficiency d2 (white circle) is closer to the line segment of the high-speed 6-cylinder engine.

As described above, each cylinder is equipped with a low-speed specification cylinder and a high-speed specification cylinder. During low-speed operation, the amount of fuel injection to the high-speed specification cylinder that is suitable for low-speed operation is increased to increase the impact of combustion in the low-speed specification cylinder. During operation, the influence of combustion in the high-speed specification cylinder can be increased by increasing the fuel injection amount to the high-speed specification cylinder suitable for high-speed operation.
Thus, by increasing the influence degree of the cylinder suitable for the operating state according to the operating state of the engine, it is possible to compensate for the performance deterioration in the cylinder not suitable for the operating state.

Further, the engine 1 has the same number of cylinders with different specifications from the low-speed specification three cylinders and the high-speed specification three cylinders, and when increasing the fuel supply amount to one cylinder, the fuel to the other cylinder is increased by the increase amount. The injection amount is reduced.
In this way, the amount of fuel supplied to one cylinder is increased and the amount of fuel supplied to the other cylinder is reduced, so that the torque output for each cylinder as a whole satisfies the torque required for the engine. Torque fluctuations can be suppressed with easy control.

From these things, the deterioration of the engine performance resulting from the specification of a cylinder can be suppressed in the whole operation area | region, and the performance suitable for actual driving | running | working is realizable.
This is the end of the description of the embodiment of the fuel injection control device for a multi-cylinder engine according to the present invention, but the embodiment is not limited to the above embodiment.
In the above embodiment, the engine 1 is an in-line 6-cylinder diesel engine, but the type of the engine is not limited to this. For example, the number of cylinders is not limited to six, and a multi-cylinder engine such as four or eight cylinders may be used. Further, the combination of the number of low-speed specification cylinders and the number of high-speed specification cylinders is not limited to the low-speed specification three-cylinder high-speed specification three-cylinders. A combination of cylinders, one cylinder, and five cylinders may be used.

# 1 to # 3 Low speed specification cylinder # 4 to # 6 High speed specification cylinder 1 Engine 2 Fuel injection valve (fuel supply means)
30 ECU (fuel supply control means)

Claims (4)

An engine having a plurality of cylinders composed of a first cylinder with specifications adapted for low-speed operation and a second cylinder adapted for high-speed operation compared to the first cylinder;
Fuel supply means configured to correspond to the specifications of the cylinder, and supplying fuel into the corresponding cylinder;
The fuel supply means is controlled so that the fuel supply amount to the first cylinder is increased from the fuel supply amount to the second cylinder during low speed operation, and the fuel supply amount to the second cylinder during high speed operation. Fuel supply control means for increasing the fuel supply amount to the first cylinder,
A fuel injection control device for a multi-cylinder engine.   The number of cylinders of the first cylinder and the second cylinder is the same, and when the amount of fuel supplied to one cylinder is increased, the amount of fuel supplied to the other cylinder is decreased by the increased amount. The fuel injection control device for a multi-cylinder engine according to claim 1.   The first cylinder has a specification that produces less smoke during low speed operation than the second cylinder, and the second cylinder has a specification that produces less smoke during high speed operation than the first cylinder. The fuel injection control device for a multi-cylinder engine according to claim 1 or 2.   The first cylinder has a specification that the fuel consumption rate is lower than that of the second cylinder during low-speed operation, and the second cylinder has a specification that has a fuel consumption rate lower than that of the first cylinder during high-speed operation. The fuel injection control device for a multi-cylinder engine according to claim 1 or 2.

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