JPS6354136B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled injection timing control device for a fuel injection pump for a diesel engine.

Figure 1 shows a conventional example of this type of injection timing control device.
This will be explained based on FIG.

FIG. 1 shows the mechanical part of an injection timing control device for a distributed fuel injection pump. The timer piston 1 engages via a pin 2 in a roller holder (none of which is shown) which holds a roller that contacts a cam disk integral with the pump/dispensing plunger. A high pressure chamber 4 is formed on one end surface of the timer piston 1, into which high pressure fuel within the pump housing is guided through an orifice 3. Further, a low pressure chamber 5 connected to a low pressure fuel source is formed on the other end side, and a spring 6 is housed in this low pressure chamber 5. And hyperbaric chamber 4
A passage 7 for escaping fuel from the low pressure chamber 5 is provided,
This passage 7 is provided with an electromagnetic control valve 8 for controlling the amount of relief.

Therefore, by controlling the valve opening duty (pulse width of a constant cycle drive pulse) of the control valve 8, the fuel pressure in the high pressure chamber 4 is controlled, and the position of the timer piston 1, that is, the injection timing (advance amount) is controlled. is controlled. Incidentally, as the opening duty of the control valve 8 is reduced, the fuel pressure in the high pressure chamber 4 increases, the stroke amount of the timer piston 1 to the right in the diagram increases, and the advance amount increases.

FIG. 2 shows the configuration of the control circuit for the control valve 8. The TDC signal from the TDC sensor that detects the top dead center (TDC) position of each engine cylinder (see Figure 3), the lift signal from the lift sensor that detects the valve lift of the fuel injection valve of a specific cylinder (see Figure 3) )
A lever opening signal from a lever opening sensor that detects the opening of the control lever of the fuel injection pump is input to the microcomputer 9. However, since the lever opening signal is an analog signal, the A/D converter 10 is used. Based on these input signals, the microcomputer 9 controls the valve opening duty (hereinafter referred to as iT duty) of the control valve 8 as shown in the flowchart of FIG.

Following the flowchart, in S1,
A target injection timing (hereinafter referred to as target iT) that is predetermined based on the engine rotation speed N obtained by calculating the reciprocal of the period between TDC signals and the lever opening (load) α to pull up the table. Next, in S2, the lift signal from the lift sensor of a specific cylinder and the TDC of the same cylinder are determined.
The actual injection timing (hereinafter referred to as actual iT) is calculated by calculating the interval with the signal (see Figure 3). Of course, these target iT and actual iT are obtained as advance angle amounts.

Next, in S3, the rate of change in the lever opening degree α is calculated and compared with a predetermined value to determine whether or not there is acceleration (the rate of change is greater than or equal to the predetermined value).

When not accelerating, proceed to S4 and compare the actual iT and target iT. As a result, the actual IT is smaller and the target
If the difference from iT is greater than a predetermined value, it is determined in S5 whether or not it is the first time.
The injection timing is proportionally controlled in the advance direction by giving a proportional amount -P in the decreasing direction (valve opening time decreasing direction) to the duty, and from the second time onwards, the iT duty is decreased by 1 step at a predetermined integral speed in S7. integrally controls the injection timing in the advance direction. Also, if the actual iT is larger and the difference from the target iT is more than a predetermined value,
In S8, it is determined whether or not it is the first time, and if it is the first time, in S9, a proportional amount +P in the increasing direction is given to the iT duty to proportionally control the injection timing in the retarding direction.
From the second time onward, in S10, the iT duty is increased by one step at a predetermined integral speed, and the injection timing is integrally controlled in the retarded direction. Of course, if the actual iT is in the dead zone set with respect to the target iT (actual iT
and the target iT is less than a predetermined value), the iT duty is maintained at the current level.

When accelerating, proceed to S11 to determine whether or not it is the first time. If it is the first time, in S12, give a large acceleration proportion -Pa in the decreasing direction to the iT duty and change the injection timing in proportion to the advance direction. control, and follow the normal flow from the second time onwards.

In this way, the actual iT and target iT are compared to perform proportional-integral control of the iT duty, and when accelerating, a large proportion of acceleration is given to improve responsiveness during acceleration.

However, in such conventional injection timing control devices, an acceleration proportional amount is given for the purpose of improving followability of injection timing control during acceleration, but for example, as shown in FIG. There has been a problem in that after the minute is given, the acceleration proportional component is immediately canceled out by the proportional component of the normal proportional-integral control, which may impair the followability of the injection timing control during acceleration.

The present invention has been made to solve these conventional problems, and includes an acceleration detection means for detecting acceleration, and an acceleration proportional component that is larger than the proportional component of normal proportional-integral control at the time of acceleration detection. In addition to providing an acceleration proportional component output means for outputting the acceleration proportional component, by providing a proportional component cutting device that cuts the proportional component of the normal proportional integral control within a certain period of time after acceleration detection, the effect of applying the acceleration proportional component is impaired. This is to ensure stable followability of injection timing control during acceleration.

An embodiment of the present invention will be described below with reference to a functional block diagram of a microcomputer shown in FIG. 6 and a flowchart shown in FIG. Incidentally, the mechanical part is the same as the conventional example (FIG. 1).

The configuration will be explained with reference to FIG. 6: a rotation speed calculation means 11 that calculates the engine rotation speed N from the TDC signal, and a target iT search means 12 that searches for the target iT from the engine rotation speed N and the lever opening degree α. and,
An implementation that calculates the actual iT from the TDC signal and lift signal.
iT calculation means 13, comparison means 14 for comparing target iT and actual iT, P component output means 15 and I component output means 16 for performing proportional-integral control in a direction according to the comparison result of this comparison means 14. and is provided.

Further, an acceleration detecting means 17 that detects acceleration by calculating the rate of change of the lever opening degree α, an acceleration P minute output means 18 that is activated when acceleration is detected, and a P that is activated by a timer 19 within a certain period of time after acceleration is detected. A portion cutting means 20 is provided. In addition, 21 is iT
It is a duty calculation means.

Next, the operation will be explained with reference to the flowchart shown in FIG.

Search for target iT using target iT search means 12 (S1)
Then, the actual iT is calculated by the actual iT calculation means 13 (S2)
After that, the acceleration detection means 17 determines whether or not there is acceleration (S3, S11).

When acceleration is detected, acceleration P minute output means 1
Acceleration P (-Pa) is given to the iT duty by 8 (S12). Also, at this time, the timer 19 is started.

During acceleration or other than acceleration, comparison method 1
In step 4, the actual iT and the target iT are compared (S4), a control direction is determined according to the result, and the P-minute output means 15 and the I-minute output means 16 are operated. At this time, if it is within a certain period of time after acceleration is detected, the timer 19 activates the P minute cut means 20 and the P minute output means 15 becomes inactive.

To explain this part in detail using a flowchart, as a result of comparing the actual iT and target iT in S4, the actual iT
is smaller and the difference from the target iT is greater than or equal to a predetermined value, it is determined in S5 whether or not it is the first time. 1
At the second time, the elapsed time after acceleration detection is determined in S13, and if the predetermined time has elapsed, the proportional amount -P in the decreasing direction is given to the iT duty in S6, and the injection timing is proportionally controlled in the advancing direction. However, within a predetermined time, the iT duty is maintained at the current level without giving the proportional amount. From the second time onward, in S7, the iT duty is decreased by one step at a predetermined integral speed, and the injection timing is integrally controlled in the advance direction.

If the actual iT is larger and the difference from the target iT is greater than or equal to a predetermined value, it is determined in S8 whether or not this is the first time. At the first time, the elapsed time after acceleration detection is determined in S14, and if the predetermined time has elapsed,
In S9, a proportional amount +P in the increasing direction is given to the iT duty to proportionally control the injection timing in the retarding direction.
Within the specified time, without giving a proportional amount,
Maintain iT duty as it is. From the second time onwards, use S10 to set the iT duty to 1 at the specified integral speed.
The injection timing is integrally controlled in the retarded direction by increasing the injection timing step by step.

Of course, if the actual iT is in the dead zone of the target iT, the iT duty is maintained at the current state.

In this way, as shown in Figure 8, even if the relationship between actual iT and target iT is reversed within a certain period of time after acceleration is detected and a large proportion of acceleration is given, without giving any
Since only the direction of the integral control is changed, the acceleration proportional component will not be immediately canceled by the proportional integral control component after the acceleration proportional component is applied.
The effect of applying the acceleration proportional portion can be sufficiently exerted, and the followability of injection timing control during acceleration can be made stable.

As explained above, according to the present invention, it is possible to stabilize the followability of injection timing control during acceleration, and it is possible to obtain the effect that acceleration performance can be improved.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of an injection timing control device for a distribution type fuel injection pump, Fig. 2 is a configuration diagram showing a conventional example of a control circuit, Fig. 3 is a time chart of the above, Fig. 4 is a flow chart of the same, FIG. 5 is a conventional control characteristic diagram, FIG. 6 is a functional block diagram showing an embodiment of the present invention, FIG. 7 is a flowchart of the same, and FIG. 8 is a control characteristic diagram of the present invention. 1...Timer piston, 4...High pressure chamber, 5...
...Low pressure chamber, 6...Spring, 7...Escape passage, 8...Control valve, 12...Target iT search means,
13...actual iT calculation means, 14...comparison means, 1
5... P minute output means, 16... I minute output means, 1
7... Acceleration detection means, 18... Acceleration P minute output means, 19... Timer, 20... P minute cut means.

Claims (1)

[Claims] 1. A timer piston that determines the injection timing according to the stroke position, a passage that releases high-pressure fuel that acts on and displaces the timer piston, and an electromagnetic control valve that is interposed in the passage and controls the amount of release. A fuel injection pump for a diesel engine, which controls injection timing by proportional-integral control of a control valve opening duty by comparing a target injection timing determined by engine operating conditions with an actual injection timing. In the injection timing control device of 1. An injection timing control device comprising a proportional component cutting means for cutting a proportional component of normal proportional integral control.