JPH022918Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an injection timing control device for a fuel injection pump for a diesel engine, and particularly to one that improves control stability.

An example of this type of injection timing control device will be explained based on FIGS. 1 to 4. FIG. 1 shows a portion related to an injection timing control device of a distributed fuel injection pump.
In the figure, a timer piston 1 is engaged with a roller holder (none of which is shown) that contacts a cam disk integral with a fuel injection plunger. The timer piston 1 has a high-pressure chamber 2 on one end side into which high-pressure fuel is introduced, and a low-pressure chamber 2 on the other end side that communicates with a low-pressure fuel source and is equipped with a spring 3 that biases the timer piston 1 toward the high-pressure chamber 2. A chamber 4 is formed, and these high pressure chamber 2 and low pressure chamber 4 are connected to an electromagnetic timing control valve (hereinafter referred to as TCV).
It is connected by a bypass passage 6 with a bypass passage 5 interposed therebetween. And the energization time of the TCV5, that is,
By controlling the valve opening duty (hereinafter referred to as iT duty), the amount of fuel bypassed from the high pressure chamber 2 to the low pressure chamber 4 via the bypass passage 6 is adjusted, thereby controlling the fuel pressure in both chambers and setting the timer. The position of the piston 1, that is, the fuel injection timing (start timing) is controlled. Here, the injection timing is advanced as the timer piston 1 moves toward the low pressure chamber 4 side, that is, as the iT duty is reduced to reduce the amount of bypass fuel and as the fuel pressure in the high pressure chamber 2 is increased. .

Next, a conventional general injection timing control method in such an apparatus, that is, a duty control method for the TCV 5 will be explained.

Figure 2 shows the configuration of the control circuit.The control unit 7 uses the TDC signal from the TDC sensor that detects the top dead center position of each engine cylinder, and the actual injection start timing of the fuel injection valve using the valve lift. A lift signal from a lift sensor that detects, a lever opening signal and an engine rotation speed signal from a lever opening sensor that detects the opening (engine load) of the governor control lever of the fuel injection pump, and the like are input. Based on these signals, the control unit 7 performs PI control of the iT duty as shown in the flowchart of FIG. First, the target injection timing iTS corresponding to the engine operating condition is determined based on the engine speed signal and the opening signal of the governor control lever of the fuel injection pump (step 1), and the lift signal is determined as shown in Fig. 4. The actual injection amount timing iTM corresponding to the injection start timing is determined by determining the interval from when the TDC signal is input, that is, after the start of fuel injection for the cylinder concerned until the input of the TDC signal (Step 2). . Next, it is determined whether or not the actual injection timing iTM falls within an error range (hereinafter referred to as dead zone) centered on the target injection timing iTS (step 3). Then, when iTM is in the dead zone, iTM≒iTS is assumed and the iT duty is maintained at the current level (step 4), and when it is not in the dead zone, the rate of change of ΔiT = iTS - iTM is determined and the positive or negative of this is determined. After that, it is determined whether ΔiT is positive or negative in each case (steps 5, 6, and 7). When the rate of change of ΔiT is positive, and when ΔiT<0, the iT duty is controlled in the retard direction (step 8), and ΔiT>
When it is 0, this condition is the first time (see Figure 5).
A ₂ points, Step 9) A proportional amount (-P) in the negative direction, that is, in the advance angle direction is given to the iT duty (Steps 9 and 10), and thereafter I control is performed in the advance direction (Step 11). On the other hand, if the rate of change of ΔiT is negative, when ΔiT > 0, the iT duty is controlled in the advance direction (step 12), and when ΔiT < 0, this condition is the first time that this condition is met (step 5). ₁ point A in the diagram,
Step 13) A proportional amount P in the positive direction, that is, in the retard direction is given to the iT duty (step 14), and thereafter I control is performed in the retard direction (step 15).

In this way, control is performed to match iTM to iTS by giving a proportional amount in the direction of entering the dead zone when iTM leaves the dead zone.

However, in such conventional PI control method,
I control (integral control) even when ΔiT becomes large
However, there was a problem in that it took a long time to enter the dead zone again, and the engine operating performance deteriorated during that time.

The present invention was developed in view of these conventional problems, and by providing a means for giving a proportional amount even when passing through a zone boundary point that is set wider than the dead zone around the target injection timing iTS,
An object of the present invention is to provide an injection timing control device for a fuel injection pump for a diesel engine, which quickly and stably sets the actual injection timing iTM within a dead zone, thereby achieving good injection timing control performance. .

The present invention will be explained below based on illustrated embodiments. FIG. 6 shows the configuration of a control circuit in an embodiment of the present invention, in which the control unit 11 is an iTS
It is configured to include an arithmetic circuit 11A, an iTM arithmetic circuit 11B, a ΔiT arithmetic circuit 11C, a first comparison circuit 11D, a second comparison circuit 11E, a ΔiT change rate arithmetic circuit 11F, and a PI control circuit 11G.

Next, the control operation of this embodiment will be explained according to the flowchart shown in FIG. iTS, iTM by iTS arithmetic circuit 11A and iTM arithmetic circuit 11B
(Steps 21 and 22) and calculate ΔiT calculation circuit 11C.
The first comparison circuit 11D determines whether iTM is within the dead zone based on ΔiT determined by (step 23). When iTM is in the dead zone, maintain the iT duty at the current level (step 24), and when it is out of the dead zone, ∆iT
The rate of change calculation circuit 11F determines the rate of change of ΔiT and determines whether it is positive or negative (step 25). and,
If the rate of change of ΔiT is positive, it is determined whether ΔiT is positive or negative (step 26), if ΔiT<0, the iT duty is controlled in the retarded direction (step 27), and if ΔiT>, the second comparator circuit Due to 11E, iTM is ± from iTS
It is determined whether it is within a set zone that is wider than the dead zone between two boundary points separated by A (step 28), and if it is within the set zone,
When this condition is met for the first time by the PI control circuit 11G ( ₃ points B in Fig. 8, step 29), a proportional amount -P ₁ in the advance direction is given to the iT duty (step 30), and the second
After the first time, I control is performed in the advance direction (step 30,
31). In addition, when it is out of the setting range, the PI control circuit 11G sets the condition for the first time (see Fig. 8).
B ₄ points) Give the iTS duty a proportional amount _-P2 in the advance angle direction (steps 32, 33), and perform I control in the advance direction from the second time onwards (step 31).

On the other hand, if the rate of change of ΔiT is negative, it is determined whether ΔiT is positive or negative (step 26'), and if ΔiT>0, the iT duty is controlled in the advance direction (step 34).
When ΔiT<0, it is determined whether or not iTM is included in the setting zone (step 35), and if it is included, a proportional amount _P1 in the retard direction is given to the iT duty for the first time (step 35). Figure 8 B ₁ point, steps 36, 37),
After the second time, I control is performed in the retard direction (step
38). Furthermore, when the iTM is outside the setting zone, the proportional amount P ₂ in the retard direction is applied for the first time (Fig. 8 B ₂ points, steps 39 and 40), and from the second time onwards, I control is performed in the retard direction (step 38).

In this way, not only the moment when the iTM leaves the dead zone, but also the moment when the iTM leaves the set zone, the iTS
Since a proportional portion is given in the direction closer to , even if ΔiT becomes large, the time until iTM is returned to the dead zone is shortened, and the injection timing control characteristics and eventually the engine operating characteristics can be stabilized.

FIG. 9 is a flowchart showing the control operation of another embodiment of the present invention. That is, in this embodiment, in addition to the PI control in the first embodiment,
At the moment when the iTM enters the set zone and the dead zone, control is performed to give a proportional amount in the direction of moving out of these zones. Specifically, after calculating iTS and iTM (steps 51 and 52), determining whether ΔiT is positive or negative (step 53),
Determining whether the ΔiT change rate is positive or negative (steps 54 and 55),
Determining whether the iTM is in the dead zone (steps 56 to 59), determining when the dead zone is passed (steps 62, 66, 76, 79), determining whether the iTM is in the set zone (step 68) , 71, 72, 75), determination when passing the set zone (steps 77, 78, 80, 81)
I do. As a result, the iTM shown in FIG. 10A determines eight passing points (C ₁ to C ₈ ) at which the iTM passes through the dead zone and the set zone. And in the same figure
At each point C ₃ , C ₄ , C ₇ , C ₈ at the moment when iTM deviates from the dead zone and set zone, proportional portions of +P ₁ , +P ₂ , −P ₁ , −P ₂ are sequentially given as in the previous embodiment, and At point C ₁ and C ₂ at the moment when ΔiT > 0 and iTM enters the set zone and dead zone, +P ₂ ,
Give the proportional component of +P ₁ , and if ΔiT<0
At points C ₅ and C ₆ at the moment when iTM enters the set zone and dead zone, the proportional portions of −P ₂ and −P ₁ are given.

FIG. 10B shows the characteristics of iT duty in such PI control. In this way, when iTM enters the setting zone and dead zone, the
Since a proportional amount is given in the opposite direction to the direction in which the iTM changes, the speed at which it approaches the iTS is reduced stepwise, and this momentum can be used to suppress overshoot when it leaves the dead zone. That is,
When the iTM tries to move away from the iTS, it is controlled so that it is quickly returned to the dead zone by giving it a proportional amount similar to the previous embodiment, while when it tries to approach the iTS, it is given a proportional amount in the opposite direction to reduce its momentum. This suppresses hunting and provides stable control characteristics.

As explained above, according to the present invention, iTM
The iTM
When the iTS fluctuates, it can be quickly set within the iTS dead zone, resulting in the effect that the injection timing control characteristics can be stabilized and, in turn, the engine performance can be stabilized.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the part related to the electronic injection timing control device of a general distribution type fuel injection pump, Fig. 2 is a block diagram showing the control circuit of the conventional electronic injection control device, and Fig. 3 is the same as above. A flowchart showing the control flow of the device, FIG. 4 is a time chart showing a method for detecting the actual injection timing in the same device, and FIG. 5 shows the injection timing characteristics and P by the same device.
A diagram showing control points, FIG. 6 is a control block diagram showing an embodiment of the present invention, FIG. 7 is a flowchart showing the control operation of the above embodiment, and FIG. 8 is a diagram showing the injection timing characteristics and FIG. 9 is a flowchart showing the control operation of another embodiment of the present invention; FIG. 10A is a diagram showing the injection timing control characteristics and P control point of the same embodiment; FIG. B is a diagram showing the iT duty control characteristics of the same embodiment. DESCRIPTION OF SYMBOLS 1...Timer piston, 2...High pressure chamber, 4...Low pressure chamber, 5...Timing control valve, 6...Bypass passage, 11...Control unit, 11
A...iTS arithmetic circuit, 11B...iTM arithmetic circuit, 11
C...∆iT calculation circuit, 11D...first comparison circuit, 11
E...Second comparison circuit, 11F...ΔiT change rate calculation circuit, 11G...PI control circuit.

Claims (1)

[Scope of utility model registration request] A high-pressure chamber defined on both sides of the timer piston, into which high-pressure fuel is guided, and a low-pressure chamber, into which low-pressure fuel is led, are connected by a bypass passage interposed with an electromagnetic timing control valve, and the opening duty of the timing control valve is proportionally controlled. An injection timing control device for a fuel injection pump for a diesel engine, which controls the fuel injection timing determined by the timer piston position by integral control so as to approach a preset target injection timing,
A duty that provides a proportional amount to the valve opening duty of the timing control valve when the actual injection timing passes through a boundary point of a dead zone set near the target injection timing and a set point set away from the target injection timing from the boundary point. An injection timing control device for a fuel injection pump for a diesel engine, comprising a control means.