WO2012169382A1

WO2012169382A1 - Fuel-injection-control device

Info

Publication number: WO2012169382A1
Application number: PCT/JP2012/063612
Authority: WO
Inventors: 富雄志垣
Original assignee: ナブテスコ株式会社
Priority date: 2011-06-07
Filing date: 2012-05-28
Publication date: 2012-12-13
Also published as: JP2012251532A

Abstract

A fuel-injection-control device (2) inputs an engine-speed signal from a speed sensor (10) and a set-speed signal transmitted by an operating device (3), and calculates an injection-quantity command for a fuel-injection pump (6) based on at least the engine-speed signal and the set-speed signal. The fuel-injection-control device (2) is provided with a limiter (16) for restricting the minimum amount of injected fuel per event, and the limiter (16) changes the minimum amount of injected fuel according to the engine-speed signal.

Description

Fuel injection control device

The present invention relates to a fuel injection control device for controlling the fuel injection amount in an engine such as a diesel engine.

For example, Patent Document 1 discloses a fuel injection control apparatus as described above. In the technique of Patent Literature 1, idle rotation control is performed so as to keep the engine idle rotation speed constant in a state in which the load by an auxiliary machine of the engine such as power steering or alternate is high, depending on the state of the engine load. The minimum amount of fuel injected into the engine is specified.

JP-A-61-232447

According to the technique of Patent Document 1, a minimum injection amount is defined. This minimum injection amount is an injection amount per injection that is an injection amount when an injection amount adjustment instruction is given once. It is specified. In the case where the injection amount per one time is defined in this way, if the injection amount is increased frequently in order to increase the engine speed, the injection amount per unit time increases and the driving force also increases. For example, even if it is controlled to the minimum injection amount in order to increase the engine speed during no-load operation and then return the engine speed to the idle speed, the injection amount per unit time increases. As a result, the driving force of the engine is increased, and the engine speed does not decrease.

It is an object of the present invention to provide a fuel injection control device that can reliably reduce the engine speed to an idle speed even in a no-load state.

In the fuel injection control device according to one aspect of the present invention, an engine speed signal indicating the engine speed detected by the speed detector and a set speed signal transmitted from the control device are input, and at least detected. An injection command to the fuel injection device is calculated from the engine speed signal and the transmitted set speed signal. PID control means can be used to calculate the injection command. The fuel injection control device includes a limiter unit that defines a minimum injection amount per one time. The limiter unit changes the minimum injection amount in accordance with the detected engine speed. An upper limit of the minimum injection amount can be defined, a lower limit can be defined, or both can be defined.

In this fuel injection control device, the limiter unit changes the minimum injection amount according to the detected engine speed. For example, when the engine speed increases in a no-load state, the increased engine speed is detected. Since the minimum injection amount is controlled based on the detected increased engine speed, the engine speed can be reliably reduced to the idle speed even in a no-load state.

As described above, according to the present invention, the rotational speed can be reliably reduced to the idle rotational speed even in a no-load state.

It is a block diagram of the fuel-injection control apparatus of one Embodiment of this invention. It is a figure which shows the maximum fuel control state by the limiter part in the fuel-injection control apparatus of FIG. It is a figure which shows the minimum fuel control state by the limiter part in the fuel-injection control apparatus of FIG.

As shown in FIG. 1, the fuel injection control device 2 of one embodiment of the present invention controls an engine, for example, a fuel injection device of a diesel engine 4 that drives a screw 3 of a ship, for example, an actuator 8 that drives a fuel pump 6. To do.

The fuel injection control device 2 is supplied with a set rotational speed signal from the control device 3. Further, the rotation speed of the rotating body 5 provided on the rotating shaft of the diesel engine 4, that is, the rotation speed detector for detecting the rotation speed of the diesel engine 4, for example, the engine speed signal output from the pulse generator 10 is also supplied to the fuel injection control device. 2 is supplied. The set rotational speed signal and the engine rotational speed signal are input to an adder 12 in the fuel injection control device 2, and the adder 12 calculates a difference between the set rotational speed and the engine rotational speed, and a difference signal representing the difference is obtained. Output from the adder 12.

The difference signal from the adder 12 is supplied to the PID controller 14 and converted into an output signal having a value suitable for PID control. The output signal of the PID controller 14 is limited by the limiter unit 16 and output. The limiter unit 16 can be configured by a microcomputer, for example, and the function thereof will be described later.

The output signal of the limiter unit 16 is supplied to the adder 18. A position signal representing the position of the actuator 8 is also supplied to the adder 18, and a difference signal representing a difference between the output signal of the limiter unit 16 and the position signal representing the position of the actuator 8 is calculated as an output signal of the adder 18. It is supplied to the actuator drive unit 20. The actuator drive unit 20 controls the position of the actuator 8 according to the output signal of the adder 18. The actuator 8 is coupled to the fuel pump 6 via the link mechanism 22, the fuel supply amount is adjusted according to the position of the actuator 8, and the rotational speed of the diesel engine changes. Such a change in the rotational speed by adjusting the fuel supply amount is performed, for example, every time the set rotational speed is changed and every time the actual rotational speed of the diesel engine 4 is changed. That is, the minimum injection amount, which is the fuel injection amount when the injection amount adjustment instruction is given once, is controlled.

Since the limiter unit 16 is provided, the overload of the diesel engine 4 is prevented and the stall of the diesel engine 4 due to a significant change in the set rotational speed is prevented.

To prevent overload, the PID controller 14 determines that the position of the actuator 8 is equal to or greater than a predetermined maximum position Y5 (the position of the actuator 8 can take a position larger than the maximum position Y5). 2, the limiter unit 16 limits the output signal of the PID controller 14 so as not to make the position of the actuator 8 larger than the maximum position Y5 as shown in FIG. It has been broken.

Also, the position of the actuator 8 is limited according to the actual rotational speed X represented by the engine rotational speed signal. For example, depending on which of a plurality of predetermined rotation speed ranks the actual rotation speed X belongs to, the position of the actuator 8 is set to a limit value determined for each rank, for example, a variable limit value determined based on the actual rotation speed for each rank. Is limited.

For example, even if the output of the PID controller 14 indicates that the position of the actuator 8 exceeds a predetermined first overload prevention position, for example, Y1 (Y1 <Y5), the actual rotational speed X is the predetermined The rotation speed is limited to Y1 until it becomes larger than 1 overload prevention rotation speed, for example, X1 rpm. That is, the upper limit value of the position of the actuator 8 is defined. When the actual rotational speed X is X1 rpm or less and the position of the actuator 8 indicated by the output signal of the PID controller 14 is smaller than Y1, the limiter unit 16 does not limit the output signal of the PID controller 14. Output as is.

If the actual rotational speed X is between X1 rpm and a predetermined second overload prevention rotational speed, for example, X2 (X2> X1) rpm, the position of the actuator 8 is the actual rotational speed X at that time. Y2 to Y2 that are determined according to a linear function having an argument of the actual rotational speed X as an argument, for example, a value in a range from Y1 to the second overload prevention position determined according to Y2, for example, Y2 (Y5> Y2> Y1) Even if the output signal of the PID controller 14 indicates that the value A on the connecting line exceeds, specifically, [(Y2-Y1) * (X−X1) / (X2−X1)] + Y1, the actuator 8 Is limited to A as described above. That is, the upper limit value of the position of the actuator 8 is defined. When the actual rotational speed X is between X1 rpm and X2 rpm and the output signal of the PID controller 16 indicates that the position of the actuator 8 should be smaller than the value A determined by the actual rotational speed X, the limiter The unit 16 outputs the output signal of the PID controller 14 as it is.

When the actual rotational speed is between X2 rpm and a predetermined third overload prevention rotational speed, for example, X3 rpm, the position of the actuator 8 is determined from Y2 determined according to the actual rotational speed X to a predetermined third speed. Overload prevention position, for example, a value in the range of Y3 (Y5> Y3> Y2), for example, a value B on the line connecting Y3 and Y2 determined according to a linear function with the actual rotational speed X as an argument, specifically Specifically, even if the output signal of the PID controller 14 indicates that [(Y3−Y2) * (X−X2) / (X3−X2)] + Y2 is exceeded, the position of the actuator 8 is B described above. To the maximum. That is, the upper limit value of the position of the actuator 8 is defined. When the actual rotational speed X is between X2 rpm and X3 rpm and the output signal of the PID controller 16 indicates that the position of the actuator 8 should be smaller than the value B determined by the actual rotational speed X, the limiter The unit 16 outputs the output signal of the PID controller 14 as it is.

When the actual rotation speed X is between X3 and a predetermined fourth overload prevention rotation speed, for example, X4 rpm, the position of the actuator 8 is determined from Y3 determined according to the actual rotation speed X to a predetermined first rotation speed. 4 overload prevention position, for example, a value in a range of Y4 (Y5> Y4> Y3), for example, a value C on a line connecting Y4 and Y3, which is determined according to a linear function with the actual rotational speed X as an argument, Specifically, even if the output signal of the PID controller 14 indicates that [(Y4-Y3) * (X−X3) / (X4−X3)] + Y3 is exceeded, the position of the actuator 8 is as described above. C is maximally limited. That is, the upper limit value of the position of the actuator 8 is defined. When the actual rotational speed X is between X3 rpm and X4 rpm and the output signal of the PID controller 16 indicates that the position of the actuator 8 should be smaller than the value C determined by the actual rotational speed X, the limiter The unit 16 outputs the output signal of the PID controller 14 as it is.

When the actual rotational speed X is between X4 and a fifth overload prevention rotational speed, for example, X5 rpm, the output signal of the PID controller 14 indicates that the position of the actuator 8 exceeds Y5 from Y4 described above. However, the position of the actuator 8 is a value in the range of Y4 to Y5 determined according to the actual rotational speed Xrpm, for example, a value on the line connecting Y5 and Y4 determined according to a linear function with the actual rotational speed X as an argument. D, specifically, even if the output signal of the PID controller 14 indicates that [(Y5−Y4) * (X−X4) / (X5−X4)] + Y4 is exceeded, the position of the actuator 8 is It is limited to D mentioned above to the maximum. That is, the upper limit value of the position of the actuator 8 is defined. When the actual rotational speed X is between X4 rpm and X5 rpm and the output signal of the PID controller 16 indicates that the position of the actuator 8 should be smaller than the value D determined by the actual rotational speed X, the limiter The unit 16 outputs the output signal of the PID controller 14 as it is.

Since the limiter unit 16 operates as described above, the engine speed signal is supplied from the pulse generator 10 to the limiter unit 16 to limit the output of the PID controller 14.

Further, the stall of the diesel engine 4 is prevented by limiting the output signal of the PID controller 14 by the limiter unit 16 as shown in FIG. 3 according to the rotational speed. The limitation on the output signal varies depending on which of the plurality of ranks the actual rotational speed X belongs to.

For example, when the rotational speed X of the diesel engine 4 is a predetermined first stall prevention rotational speed x1 rpm or less, the output signal of the PID controller 14 determines the position of the actuator 8 in the first stall prevention position. The output signal of the PID controller 14 is limited so as not to be lower than y1 even if it is instructed to be lower than y1. As a result, the minimum injection amount does not decrease below the amount corresponding to the position y1 of the actuator 8 when the rotational speed is equal to or lower than x1 rpm. That is, the lower limit value of the position of the actuator 8 is defined.

When the rotational speed of the diesel engine 4 is higher than the predetermined second stall prevention rotational speed x2 rpm (x2> x1) or higher, the position of the actuator 8 and the output signal of the PID controller 14 determine the position of the actuator. Even if the second stall prevention position y2 (y2 <y1) is instructed to be lowered, the output of the PID controller 14 is limited so as not to fall below y2. As a result, the minimum injection amount does not decrease below the amount corresponding to the position y2 of the actuator 8 when the rotational speed is x2 rpm or more. That is, the lower limit value of the position of the actuator 8 is defined.

Similarly, in a rank where the actual rotational speed X is between x1 rpm and x2 rpm, the position y of the actuator 8 is proportional to the actual rotational speed X, for example, (y2-y1) (X-x1) / (x2- x1) Even if the output signal of the PID controller 14 instructs to decrease from the position determined by + y1, the limiter unit 16 does not output a value lower than the value represented by the above equation, and the minimum injection amount is also the actuator 8 The amount does not fall below the amount corresponding to the position y. That is, the lower limit value of the position of the actuator 8 is defined.

As described above, the minimum injection amount is limited by the limiter unit 16 so as to increase as the rotational speed decreases, and conversely as it decreases as the rotational speed increases. Therefore, for example, when the actual rotational speed of the diesel engine 4 is reduced in a no-load state, the minimum injection amount increases, so the diesel engine 4 does not stop. When there is no possibility of the diesel engine 4 being stopped, the limit by the limiter unit 16 can be canceled so that the fuel injection amount is zero.

In addition, even if the injection amount per unit time increases and the driving force increases as a result of increasing the injection amount frequently in order to increase the engine speed, the minimum injection is required to return to the idle speed after that. When the amount is controlled, since the minimum injection amount is smaller as the actual rotational speed is larger, it can be easily reduced to the idle rotational speed. In the conventional apparatus, the position of the actuator 8 with the minimum injection amount is set to a constant value regardless of the actual rotational speed. In such a case, when the engine speed is increased in a no-load state, the fuel injection amount per unit time increases, and the engine speed may increase despite the minimum injection amount. When the engine speed continues to rise, an overspeed prevention device (not shown), which is one of the safety devices, operates and stops suddenly. In this embodiment, the minimum injection amount corresponding to the rotational speed is set. That is, the fuel injection amount per unit time is set to be equal to or less than the injection amount that can prevent the engine speed from increasing for each rotation speed. According to this configuration, it is possible to prevent overspeed in a high rotation range.

In addition, since the minimum injection amount is limited by the limiter unit 16 so as to increase as the actual rotational speed decreases, fuel efficiency is improved. In particular, in a large marine diesel engine, compressed air is sent to a cylinder to start the engine, so once the engine is stopped, the compressed air is wasted and it takes time to restart. Is limited by the limiter unit 16 so as to increase as the actual rotational speed decreases, the engine does not stop. In this embodiment, the minimum injection amount corresponding to the rotational speed is set. That is, the fuel injection amount per unit time is set to be equal to or less than the injection amount that can prevent the engine speed from increasing and more than the injection amount that can prevent misfire. According to this configuration, it is possible to prevent stalling in the low rotation range of the engine and overspeed in the high rotation range.

In the above embodiment, an electric type driven by the actuator 8 is shown as the fuel injection device. However, the invention is not limited to this, and a mechanical type, electromagnetic valve type, or common rail type is used. You can also.

In the above embodiment, the present invention is applied to a marine diesel engine. However, the present invention is not limited to this. For example, the present invention can also be applied to a vehicle diesel engine. In the above embodiment, in order to prevent overload, the actual rotational speed X depends on which of the six ranks X1 or less, X1 to X2, X2 to X3, X3 to X4, X4 to X5, X5 or more belongs to Although the position of the actuator 8 is changed, the number of ranks is not limited to six, and various ranks can be used as long as the rank is two or more. In addition, the upper limit value of the position of the actuator 8 is calculated based on a linear function with the actual rotation number as an argument in the ranks X1 to X2, X2 to X3, and X4 to X5, but this is not limited to this. Instead, for example, it can be calculated by a high-order function having an actual rotational speed as an argument, such as a quadratic function or a cubic function. However, the function of each rank is assumed to be continuous. In the above embodiment, in order to prevent the engine from stopping, the position of the actuator 8 is changed depending on which of the three ranks the actual rotation speed is x1 or less, x to x2, or x2 or more. For example, the range of x1 to x2 can be divided into a plurality of ranges. The ranks x1 to x2 are divided into a plurality of ranks, for example, a rank from x1 rpm to x3 rpm (x1 <x3 <x2) and a rank from x3 rpm to x2 rpm, and the actual rotational speed X is used as an argument for each rank. Even if the output signal of the PID controller represents that the position of the actuator 8 is lowered from a value obtained by a different expression, the limiter unit prevents the position of the actuator 8 from being lowered from the value represented by each of the above expressions. 16 can also limit the output signal of the PID controller 14. However, each of the above equations is continuous, and is not limited to a linear function but may be a high-order function such as a quadratic function or a cubic function.

2 Fuel injection control device 4 Diesel engine 6 Fuel pump (fuel injection device)
8 Actuator 16 Limiter

Claims

An engine speed signal representing the engine speed detected by the speed detector and a set speed signal transmitted from the control device are inputted, and at least the engine speed signal and the set speed signal are used to inject the injection device. While calculating the injection amount command to
In a fuel injection control device including a limiter unit that defines a minimum injection amount per one time,
The fuel injection control device, wherein the limiter unit changes the minimum injection amount in accordance with the engine speed signal.
2. The fuel injection control device according to claim 1, wherein the limiter unit defines an upper limit value of the minimum injection amount.
3. The fuel injection control apparatus according to claim 1, wherein the limiter unit defines a lower limit value of the minimum injection amount.