JP2006257953A - Fuel injection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve inconvenience such as a case of causing an engine stall without coping with sudden reduction in an engine speed when a maximum fuel injection quantity is restricted, since an intake rack position restricting curve RT is selected as an upper limit line, even in a state of being low in the engine speed of an engine such as idling, when uniformly performing such control, though an ECM being a control means of a fuel injection system performs processing for selecting a curve for narrowing a control range of a rack position as the upper limit line among the intake rack position restricting curve RT or a engine speed rack position restricting curve RM. <P>SOLUTION: When starting the engine 20 by operating a key switch 12a, the ECM 21 determines whether or not elapsed time after starting the engine 20 falls within a range of a predetermined time (S10), and selects the engine speed rack position restricting curve RM as the upper limit line for determining the rack position for maximizing a fuel injection quantity (S20). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel injection system that performs drive control of a rack that adjusts a fuel injection amount.

Conventionally, a fuel injection system that drives and controls a fuel injection pump that injects fuel into a cylinder of a diesel engine, a hydraulic timer unit that changes the phase of fuel injection timing, a governor that adjusts the fuel injection amount, and the like is there.
An example of such a conventional fuel injection system is described in Patent Document 1 below.
In such a fuel injection system, for example, the position of a rack built in the governor is generally driven and controlled according to the engine speed or the intake pressure of the turbocharger (turbo), and these relationships are related to the engine and fuel. It is stored in advance in an ECM, which is an example of a control unit of the injection system, as shown in FIG. 3, for example.
In the graph shown in FIG. 3, the horizontal axis indicates “engine speed” and the “intake pressure” of the supercharger, and the vertical axis indicates the rack position, and shows the following curve.
The intake rack position restriction curve RT shows the relationship between each intake pressure and the rack position that maximizes the fuel injection amount in the relationship between the intake pressure of the supercharger and the rack position. Line.
The rotational speed rack position limit curve RM shows the relationship between the engine rotational speed and the rack position that maximizes the fuel injection amount in the relationship between the engine rotational speed and the rack position. It is.
The rotation speed rack position minimum curve RS shows the relationship between the engine rotation speed and the rack position that minimizes the fuel injection amount in the relationship between the engine rotation speed and the rack position. It is.
The intake rack position restriction curve RT does not directly depend on the engine speed, but the intake rack position restriction curve RT and the rotation speed rack position restriction curve RM both have the same rack position RC (point EC). Therefore, when this point EC is considered as a reference, the intake rack position limit curve RT and the rotational speed rack position limit curve RM can be represented by one graph.
That is, the intake rack position limit curve RT can be described as if it changes depending on the engine speed.
FIG. 3 shows an example of a fuel injection system for a ship or the like.

Conventionally, the ECM determines whether the intake rack position limit curve RT or the rotation speed rack position limit curve RM is the upper limit line of the rack position as follows.
The ECM uses, as an upper limit line, a curve in which the control range of the rack position becomes narrower among the two curves according to the engine speed and the intake pressure state.
For example, when the engine is idling and the engine speed is low, that is, when the engine speed is M1 and the intake pressure is F1, the intake rack position limit curve in which the rack position control range is narrower than the rotation speed rack position limit curve RM. RT was selected as the upper limit line.
By making the selection in this way, it is possible to limit the maximum fuel injection amount, and to suppress the discharge of unburned gas and black smoke.
Therefore, in actual operation, the ECM selects, for example, the intake rack position limit curve RT as the upper limit line when the engine speed is between M1 and MC, and on the other hand, when the engine speed is between MC and M2, the speed rack position limit is selected. The curve RM was selected as the upper limit line.
That is, the curve connecting point ET1, point EC, and point EM2 is the upper limit line of the rack position.
JP 2004-218636 A

However, if the ECM uniformly performs the process of selecting the curve with the narrower rack position control range as the upper limit line among the above two curves, the maximum fuel injection amount will be increased in the following cases. There is a problem that engine stall occurs because it is restricted more than necessary.
For example, an engine stall may occur when a load is applied in a state where the engine is operating stably at a target rotational speed during idling.
This is because even when the engine speed is low, such as when idling, the intake rack position limit curve RT is selected as the upper limit line, so the maximum fuel injection amount is limited and the engine speed is limited. In some cases, the engine stalls without being able to cope with the sudden drop in the price.
In addition, as shown in FIG. 3, when the engine speed reaches the minimum set speed Mmin stored in the ECM in advance, the speed is controlled even if the rack position is controlled to follow the minimum speed rack position curve RS. Since the control is performed to increase the fuel injection amount as the value becomes lower, there is a problem that the discharge of unburned fuel increases.
Accordingly, the present invention has been made in view of the above circumstances, and its object is to provide a fuel that does not generate engine stall or the like even when a load is applied when the engine speed is low, such as during idling. It is to provide an injection system.

  The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

  The intake rack position defining a relationship between a rack for adjusting a fuel injection amount of a fuel injection pump for injecting fuel into the engine and a rack position for maximizing the intake pressure of the supercharger and the fuel injection amount. And a control means for controlling the rack based on a limit curve or a rotation speed rack position limit curve that defines a relationship between an engine speed and a rack position that maximizes a fuel injection amount. The control means is configured to control a rack position control range of either the intake rack position limit curve or the rotation speed rack position limit curve when the engine speed decreases from the target speed by a predetermined speed or more. Is provided with a curve selection means for selecting a curve having a wider width.

  The intake rack position defining a relationship between a rack that adjusts a fuel injection amount of a fuel injection pump that injects fuel into the engine and a rack position that maximizes the intake pressure of the supercharger and the fuel injection amount And a control means for controlling the rack based on a limit curve or a rotation speed rack position limit curve that defines a relationship between an engine speed and a rack position that maximizes a fuel injection amount. When the elapsed time after engine startup is within a predetermined time range, the control means has a wide rack position control range of either the intake rack position limit curve or the rotation speed rack position limit curve. Curve selection means for selecting the curve of the curve is provided.

  As effects of the present invention, the following effects can be obtained.

  According to the configuration of claim 1, when the engine speed is lower than the target engine speed by a predetermined number or more, a curve with a wider rack position control range is selected, so that the fuel injection amount is appropriately increased. This makes it possible to prevent engine stalls.

  According to the configuration of the second aspect, since the curve in which the control range of the rack position becomes wider is selected within a predetermined time after the engine is started, the engine stall is prevented by appropriately increasing the fuel injection amount. Is possible.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following best mode for carrying out the present invention is an example embodying the present invention, and is not intended to limit the technical scope of the present invention.
FIG. 1 is a block diagram showing a schematic configuration of a fuel injection system, FIG. 2 is a schematic configuration diagram of a fuel injection pump and related devices, and FIG. 3 is a rack position and engine speed at which the fuel injection amount is maximized or minimized. FIG. 4 is a flowchart showing a series of processes for preventing engine stalls, and FIG. 5 shows an example of a change in the relationship between time and engine speed at engine startup. FIG. 6 is a diagram showing an example of a change in the relationship between time and engine speed when the engine speed decreases.

<Outline configuration>
First, the schematic configuration of the fuel injection system 1 of the present invention will be described with reference to FIG.
The fuel injection system 1 described here will be described as a case where the fuel injection system 1 is used as a control system for a fuel injection pump of an engine provided in a ship, for example. However, the same effect can be obtained by using this system. As long as it is adopted, it may be adopted for any kind of thing.
As shown in FIG. 1, the fuel injection system 1 is roughly divided into an operation unit 10 and an engine 20.
The operation unit 10 is provided in the cab of the ship, and is provided with, for example, a display unit 11, a main throttle 12, a sub throttle 13, and the like.
The display unit 11 displays the state of the ship adopting this system, a warning, and the like, and can also issue a warning by voice by incorporating a speaker or the like.
The main throttle 12 operates, for example, the throttle valve 29 of the engine 20 and is operated when the ship is in a normal operation state, and is, for example, a lever type.
Further, a key switch 12 a for starting the engine 20 is provided in the operation unit 10 integrally with or separately from the main throttle 12.
The sub-throttle 13 operates the throttle valve 29 in the same manner as the main throttle 12, but is different from the main throttle 12 in that it is operated when the ship is not in a normal operation state. The shape of the sub-throttle 13 is, for example, a knob type (volume type) switch.
Each of the display unit 11 and the main throttle 12 has its own control unit, and communicates with an ECM 21 (Engine Control Module), which is a control unit on the engine 20 side, so that the operation unit 10 and the engine 20 as a whole. Control is in progress.
If the communication method such as the protocol is different between the operation unit 10 and the engine 20, a communication repeater 15 is provided for matching the communication method as shown in FIG.
The sub-throttle 13 is directly connected to the ECM 21 on the engine 20 side, and the communication system is the same as that on the engine 20 side.
The engine 20 is, for example, a diesel engine, and includes an ECM 21, a crankshaft rotational speed sensor 22, a camshaft rotational speed sensor 23, a retarding electromagnetic valve 24, an advance electromagnetic valve 25, an intake pressure sensor 27, a rack 28, and the like. It is what
The ECM 21 controls an actuator and the like related to the engine 20 based on the state of the operation system such as the sensor related to the engine 20 and the operation unit 10 described above.
The crankshaft rotation speed sensor 22 detects the rotation speed of the crankshaft of the engine 20 and outputs the detection result to the ECM 21 as a crankshaft pulse.
That is, the rotational speed of the engine 20 can be detected using the crankshaft rotational speed sensor 22.
The camshaft rotation speed sensor 23 detects the rotation speed of the camshaft of the engine 20 and outputs the detection result to the ECM 21 as a camshaft pulse.
Further, the crankshaft rotation speed sensor 22 and the camshaft rotation speed sensor 23 can be constituted by optical sensors. For example, a predetermined number of marks are provided on the crankshaft, the camshaft itself or gears at predetermined intervals at the time of manufacture. Thus, the ECM 21 can calculate the rotational speeds of the crankshaft and the camshaft 41 by detecting the mark with the optical sensor.
The delay angle solenoid valve 24 and the advance angle solenoid valve 25 are used to move the timer piston of the hydraulic timer unit for changing the cam shaft phase of the fuel injection pump 40 as shown in FIG. It is a hydraulic control valve for controlling the hydraulic pressure to slide to the side.
The intake pressure sensor 27 detects an intake pressure of a supercharger provided in the engine 20.
The rack 28 adjusts the amount of fuel injected from the fuel injection pump 40.

<Fuel injection pump>
Next, a schematic configuration of the fuel injection pump 40 and related devices will be described with reference to FIG.
The hydraulic timer unit 50 in FIG. 2 is shown in cross section.
In particular, for the sake of convenience, the timer piston 52 is shown in a state where it is vertically divided by a one-dot chain line, the state moved to the retard side position is indicated by the timer piston 52a, while the state moved to the advance side position is shown. This is indicated by the timer piston 52b.
Of course, the actual timer piston 52 is not divided into two parts by a one-dot chain line as described above, but is integrally formed. In FIG. 2, only the movement state of the timer piston 52 is described. It is divided into two by a one-dot chain line.
The fuel injection pump 40 is for pressure-feeding the fuel stored in the fuel tank to an injection nozzle provided in a cylinder of the engine 20, and is driven by a cam shaft 41. A coupling fixing member 42 for fixing the coupling 51 to the cam shaft 41 is fixed.
Further, the fuel injection pump 40 is provided with supply ports 43 for supplying fuel to the cylinders of the engine 20, and the example shown in FIG.
Further, the fuel injection pump 40 is integrally provided with a governor 30 and a hydraulic timer unit 50.
The governor 30 includes the rack 28, and the rack 28 is driven by a proportional solenoid that is driven and controlled by the ECM 21.
The hydraulic timer unit 50 is provided with a timer piston 52 that is straight and spline-fitted to the outer peripheral surface of the camshaft coupling 51, and a pump drive gear 53 that is helically spline-fitted to the outer peripheral surface of the timer piston 52. Is provided.
The pump drive gear 53 is fixed by a receiving gear 55 that receives a rotational force from the crankshaft of the engine 20 and a bolt 56.
Thus, the camshaft 41 can be rotated by the rotation of the crankshaft, and the timer piston 52 is slid in the spline direction of the camshaft coupling 51 (left and right as viewed in FIG. 2). By moving, the phase difference between the camshaft coupling 51 and the pump drive gear 53 can be changed.
Here, as already described above, the helical shape of the spline fitting is configured so that the camshaft is retarded by sliding the timer piston 52 to the 52a side and advanced by sliding the timer piston 52 to the 52b side. ing.
Further, a space formed on the outer peripheral side of the timer piston 52 fitted with the pump drive gear 53 is a retarded angle chamber 57a, and a space formed on the inner peripheral side of the timer piston 52 fitted with the camshaft coupling 51 is an advanced angle chamber 57b. Respectively.
In this case, the timer piston 52 can be slid to the retard side (52a side) by pumping the pressure oil to the retard chamber 57a, while the timer is pumped by pumping the pressure oil to the advance chamber 57b. The piston 52 can be slid to the advance side (52b side).
In addition, the retarding solenoid valve 24 and the advancement solenoid valve 25 described above are arranged in the retarding pressure fluid path 58a that leads to the retarding chamber 57a and the advancement pressure oil path 58b that leads to the advancement chamber 57b, respectively. The retard solenoid valve 24 and the advance solenoid valve 25 are controlled and operated by the ECM 21 to feed the pressure oil and slide the timer piston 52.
With this configuration, the ECM 21 functions as a control unit that hydraulically controls the timer piston 52 in accordance with the state of the engine 20, and freely delays the phase difference between the crankshaft of the engine 20 and the camshaft 41. It is possible to make an angle or advance.

<End prevention treatment>
As already described with reference to FIG. 3, the rack position (upper limit line) that maximizes the fuel injection amount is determined by the intake rack position limit curve RT or the rotational speed rack position limit curve RM stored in advance in the ECM 21. It is done.
Which curve is used as the upper limit line is determined based on the curve of which the control range of the rack position is narrower among the two curves according to the rotational speed of the engine 20 and the intake pressure of the supercharger.
Therefore, since the maximum fuel injection amount is limited, there is a case where the engine stalls without being able to cope with the sudden decrease in the engine speed when the load is applied.
A series of processes for preventing engine stall in the above case will be described with reference to FIG.

<When starting the engine>
First, when the engine 20 is started by operating the key switch 12a, the ECM 21 determines whether or not the elapsed time after the start of the engine 20 is within a predetermined time (S10).
The predetermined time is stored in advance in the ECM 21 or the like, for example, and is a time of about 2 seconds.
That is, in the process of step S10, the ECM 21 determines whether or not the elapsed time after activation is within 2 seconds.
If it is determined in step S10 that the elapsed time after the start of the engine 20 is within the predetermined time range, the process proceeds to step S20. On the other hand, if it is determined that the elapsed time is outside the range, the process proceeds to step S12. Transition.
When the process proceeds to step S20, the engine speed is between M1 and MC shown in FIG. 3 because the engine is idling immediately after startup.
At this time, since the control range of the rack position becomes wider when the rotation speed rack position limit curve RM is selected than the intake rack position limit curve RT, the ECM 21 sets an upper limit line for determining the rack position that maximizes the fuel injection amount. Then, the rotation speed rack position limit curve RM is selected (S20).
In other words, the ECM 21 also functions as an example of a curve selection unit that selects a curve having a wider rack position control range from the intake rack position limit curve RT or the rotational speed rack position limit curve RM. .
Here, when the process proceeds from step S10 to step S20, an example of a change in the relationship between time and engine speed at engine startup will be described with reference to FIG.
The time U1, the conventional engine speed curve MA1, and the processed engine speed curve MA2 shown in FIG. 5 have the following meanings.
Time U1 is the time when the engine 20 is started.
The conventional engine speed curve MA1 shows a temporal change in the engine speed when a curve having a narrower rack position control range is selected as the upper limit line as in the prior art.
The post-processing engine speed curve MA2 shows the temporal change of the engine speed when the process from step S10 to step S20 is performed and the curve with the wider rack position control range is selected as the upper limit line. thing.
In this case, immediately after the engine 20 is started at time U1, the post-processing engine speed curve MA2 is larger than the conventional engine speed curve MA1.
That is, the conventional engine speed curve MA1 stays in the vicinity of the engine speed M2 until time U2, but the processed engine speed curve MA2 reaches an engine speed M3 larger than the engine speed M2 immediately after time U1. The output is sufficient.
Further, the range of the predetermined time in step S10 is, for example, the range from time U1 to time U3, and the rotation speed rack position limit curve RM is selected as the upper limit line during this period.
As described above, by performing the processing from step S10 to step S20, the rotation speed rack position limit curve RM that increases the rack position control range is selected within a predetermined time after the engine 20 is started. The engine stall can be prevented by appropriately increasing the injection amount.

<Below the specified number of revolutions>
When the process proceeds to step S12, the ECM 21 determines whether or not the rotational speed of the engine 20 has decreased from the target rotational speed by a predetermined rotational speed or more (S12).
The predetermined rotation speed is stored in advance in the ECM 21 or the like, for example, and is a rotation speed of about 50 rotations.
If it is determined in step S12 that the rotational speed of the engine 20 has decreased from the target rotational speed by a predetermined rotational speed or more, the process proceeds to step S20. On the other hand, if it is determined that the engine speed has not decreased. The process proceeds to step S30.
Here, when the process proceeds from step S12 to step S20, description will be made with reference to FIG. 6 showing an example of a change in the relationship between the time when the engine speed decreases and the engine speed.
Note that the time U5, the conventional engine speed curve MA3, and the processed engine speed curve MA4 shown in FIG. 6 have the following meanings.
Time U5 is the time when the rotation speed of the engine 20 falls below the target rotation speed.
The conventional engine speed curve MA3 shows the temporal change in the engine speed when the curve with the narrower rack position control range is selected as the upper limit line as in the prior art.
The post-processing engine speed curve MA4 shows the temporal change in the engine speed when the process from step S12 to step S20 is performed and the curve with the wider rack position control range is selected as the upper limit line. thing.
As shown in FIG. 6, when the engine speed falls below the target speed M8 at time U5, the post-processing engine speed curve MA4 is larger than the conventional engine speed curve MA3. The return to the target rotational speed M8 is quick.
That is, the conventional engine speed curve MA3 reaches the engine speed M6 that is significantly lower than the target speed M8 at time U6, but the post-processing engine speed curve MA4 is larger than the engine speed M6 before time U6. The engine speed M9 is switched back to the target speed M8.
Further, the range of the predetermined rotational speed in step S12 is, for example, a range from the target rotational speed M8 to the engine rotational speed M5, and while the engine rotational speed is below the engine rotational speed M5, the rotational speed rack position limit curve. RM is selected.
As described above, by performing the processing from step S12 to step S20, when the rotational speed of the engine 20 is lower than the target rotational speed by a predetermined rotational speed or more, the rotational speed rack position limit curve that widens the rack position control range. Since RM is selected, the engine stall can be prevented by appropriately increasing the fuel injection amount.

<Normal control>
When the process proceeds to step S30, the control returns to the normal control as conventionally performed.
That is, the rack position (upper limit line) that maximizes the fuel injection amount is set to the upper limit of either the intake rack position limit curve RT or the rotation speed rack position limit curve RM, which has a narrower rack position control range. As a line, the ECM 21 controls the rack position.

The block diagram which showed schematic structure of the fuel-injection system. The schematic block diagram of a fuel-injection pump and its related apparatus. The figure which showed the relationship between the rack position which makes fuel injection quantity the maximum or the minimum, an engine speed, and a supercharger. The flowchart which showed a series of processes for preventing an engine stall. The figure which showed the example of a change of the relationship between the time at the time of engine starting, and engine speed. The figure which showed the example of a change of the relationship between time when an engine speed falls, and an engine speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection system 10 Operation part 15 Communication repeater 20 Engine 21 ECM
22 Crankshaft Rotational Speed Sensor 23 Camshaft Rotational Speed Sensor 24 Delay Angle Solenoid Valve 25 Advance Angle Solenoid Valve 27 Intake Pressure Sensor 28 Rack 29 Throttle Valve 30 Governor 40 Fuel Injection Pump

Claims (2)

A rack that adjusts the fuel injection amount of a fuel injection pump that injects fuel into the engine;
An intake rack position limit curve that defines the relationship between the intake pressure of the supercharger and the rack position that maximizes the fuel injection amount, or the relationship between the engine speed and the rack position that maximizes the fuel injection amount A fuel injection system comprising: control means for controlling the rack based on a rotational speed rack position limit curve;
The control means has a rack position control range of either the intake rack position limit curve or the rotation speed rack position limit curve when the engine speed decreases from the target speed by a predetermined speed or more. A fuel injection system comprising curve selection means for selecting a wider curve. A rack that adjusts the fuel injection amount of a fuel injection pump that injects fuel into the engine;
An intake rack position limit curve that defines the relationship between the intake pressure of the supercharger and the rack position that maximizes the fuel injection amount, or the relationship between the engine speed and the rack position that maximizes the fuel injection amount A fuel injection system comprising: control means for controlling the rack based on a rotational speed rack position limit curve;
When the elapsed time after starting the engine is within a predetermined time range, the control means has a wide rack position control range of either the intake rack position limit curve or the rotation speed rack position limit curve. A fuel injection system comprising curve selection means for selecting a curve of the other direction.

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