JPH1047149A - Fuel injection timing control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control all the time the operation of an engine to a target fuel infection timing by varying feed back control constant according to the stroke of a timing control valve. SOLUTION: A fuel injection timing control device is equipped with a means 22 for setting up a target fuel injection timing according to an engine operation state; a computing means 24 for actual fuel injection timing; and a means 25 which drives a timing control valve 3 on a deviation between the target injection timing and the actual injection timing to feedback-control the fuel injection timing, and moreover equipped with a means 26 for computing the stroke quantity of the timing control valve 3 and a correcting means 27 for varying the constant of the feedback control means 25 according to the above stroke quantity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device for an internal combustion engine, particularly a diesel engine.

[0002]

2. Description of the Related Art In order to accurately control the fuel injection timing of a diesel engine, conventionally, for example, Japanese Patent Application Laid-Open No. 59-153
No. 937, the fuel injection timing is feedback-controlled, and the feedback control constant is changed during acceleration operation (the feedback control constant is increased).
In some cases, the injection timing converges to the target value with good response.

[0003]

However, in this case, the feedback control constant only switches between a steady state and a transient state, and does not always correspond to the request. Depending on the operating conditions, the required feedback control constant is increased even in the steady state,
Alternatively, even in a transient state, it may become smaller on the contrary. Even in the same steady state, it may be necessary to change the feedback control constant depending on the state of the fuel injection pump.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection timing control device capable of appropriately changing a feedback control constant in accordance with a request and always accurately controlling a target fuel injection timing.

[0005]

According to a first aspect of the present invention, as shown in FIG. 15, means 21 for detecting an operating state of an engine is provided.
A means 22 for setting a target fuel injection timing according to the engine operating state; a timing control valve (3) for controlling the fuel injection timing; a means 24 for calculating the actual fuel injection timing; And a means 25 for driving the timing control valve (3) based on a deviation between the actual injection timing and the actual injection timing to perform feedback control of the fuel injection timing. And a correction means 27 for changing a constant of the feedback control means 25 in accordance with the stroke amount.

According to a second aspect of the present invention, the correction means includes means for calculating a maximum stroke amount of the timing control valve and means for calculating a current stroke amount, and changes a feedback control constant in accordance with a ratio between these. Let it.

In a third aspect, the correction means reduces the correction amount of the feedback control constant as the ratio of the current stroke amount to the maximum stroke amount of the timing control valve increases.

According to a fourth aspect of the present invention, the correction means calculates a delay from when the timing control valve is actuated to when the timing control valve is actually actuated according to the engine operating state, and according to the delay. Means for correcting the calculated value of the stroke amount of the timing control valve.

According to a fifth aspect of the present invention, the means for setting the target injection timing includes means for calculating the target injection timing according to the engine operating state, and means for correcting the target injection timing according to the engine coolant temperature.

In a sixth aspect of the invention, the means for calculating the injection timing comprises means for detecting the actual injection timing, and means for calculating the detection delay amount of the actual injection timing based on the operating state.
The actual injection timing is calculated based on both values.

[0011]

According to the first aspect of the present invention, the control duty of the timing control valve is calculated according to the difference between the target injection timing and the actual injection timing, and the fuel injection timing is controlled. In this case, the stroke sensitivity of the timing control valve increases as the stroke amount increases. Therefore, by correcting the feedback control constant according to the stroke amount, the excessive response of the timing control valve is suppressed, and the control sensitivity is constantly controlled in all control regions. In this case, the target fuel injection timing can be stably controlled regardless of whether it is transient or steady, and this has the effect of improving fuel efficiency and reducing exhaust emissions.

In the second invention, the feedback control constant is changed in accordance with the ratio between the maximum stroke amount of the timing control valve and the current stroke amount, so that an appropriate correction corresponding to the state of the fuel injection pump can be made. Becomes

In the third invention, the correction amount of the feedback control constant is reduced as the ratio of the current stroke amount to the maximum stroke amount of the timing control valve is increased. Therefore, the correction is increased in a region where the stroke sensitivity is low, and the sensitivity is also increased. In a high region, the correction is reduced, and the responsiveness of the timing control valve can be properly and stably maintained in all regions.

According to the fourth aspect of the invention, the timing control valve obtains a delay amount from the fuel injection command to the actual operation and corrects the stroke amount of the timing control valve accordingly. The responsiveness is good, and the feedback control constant is properly corrected even during a transition when the stroke amount changes.

In the fifth invention, the target injection timing set in accordance with the engine operating state is corrected in accordance with the cooling water temperature, so that the appropriate injection timing is set during and after warm-up. Can be.

In the sixth aspect, the actual injection timing is corrected so as to include the mechanical detection delay of the injection timing, so that the detection accuracy of the injection timing is increased, and the feedback control performance is correspondingly improved.

[0017]

1 is a distribution type fuel injection pump, 2 is a timer piston for controlling the fuel injection timing, and 3 is a pressure acting on a timer piston 2 (from a feed pump). The operation is controlled based on a duty signal from the controller 5 by a timing control valve that displaces the position by adjusting the low-pressure fuel pressure).

Reference numeral 4 denotes a fuel injection nozzle for injecting high-pressure fuel pumped from the fuel injection pump 1 into the engine combustion chamber.
A needle valve lift sensor 6 is provided to detect the actual injection timing.
Will be fed back. The controller 5 also receives various detection signals representing the operating state from the engine speed sensor 7, the accelerator opening sensor 8, the engine cooling water temperature sensor 9, the start switch 10, and the like, and sets a target based on these signals. The fuel injection timing is set, and the feedback control is executed so that the actual injection timing matches this target injection timing.

The controller 5 controls the feedback control constant optimally under all operating conditions to enhance the follow-up performance of the fuel injection timing control during the transient operation and ensure the stability during the steady operation. The control is performed according to the procedure shown in the flowchart.

First, the operation of calculating the control duty output from the controller 5 to the timing control valve 3 will be described with reference to FIG.

In step 1, the target injection timing Its
ol, and in step 2, the actual injection timing Itist
Is calculated. However, these calculation methods will be described later in detail. In step 3, the feedback control constants Kp, Ki, and Kd are set. This setting method will be described later in detail. Then, in step 4, Itsol, Itis, as in normal PID control
A control duty value TCVduty of the timing control valve 3 is calculated from Kp, Ki and Kd from the difference of t.

FIG. 3 is a flowchart for calculating the target injection timing Itsol.

In step 11, the operation state such as the fuel injection amount Qsol corresponding to the engine speed, the accelerator opening, etc., the start switch signal, and the cooling water temperature Tw is read. In step 12, it is determined whether or not the start switch is currently ON, that is, whether or not the engine is starting. If the start switch is ON, the process proceeds to step 13 and below.

If it is determined in step 12 that the engine is being started, then in step 13, based on the cooling water temperature Tw, a starting injection timing correction value I from a table such as that shown in FIG.
Search for t_tws. In this case, the higher the cooling water temperature, the smaller the correction value. In step 14, the injection timing correction value It_tw after starting is set to zero.

On the other hand, when the starting is completed, the injection timing correction value It_tw after starting is calculated from the table shown in FIG.
In step 16, the injection timing correction value I at the time of starting is
Let t_tws be zero.

Next, at step 17, the engine speed N
Based on e and the injection amount Qsol, a target injection timing It_ld is searched from a map as shown in FIG.

In step 18, the injection timing I
The correction values It_tws and It_t for t_ld
w, and the target injection timing It
sol is obtained, and the processing is terminated.

Next, FIG. 7 is a flow chart for calculating the actual injection timing. First, at step 21, signals representative of the operating state such as the engine speed Ne and the fuel injection amount Qsol are read, and at step 22, these signals are read. Ne and Q
The injection timing detection delay amount Itist_d is retrieved from a map as shown in FIG.

This is obtained by experimentally obtaining a hardware detection delay in detecting the actual injection timing with respect to the actual injection timing, and varies depending on Ne and Qsol.

In step 23, the injection timing Itist_dly from the lift sensor 6 for detecting the actual injection timing is read, and in step 24, the detected injection timing Iti_dly is detected.
The delay amount Itist_d is added to st_dly, and the detection timing of the lift sensor 6 is corrected in this way to obtain the actual injection timing Itist.

Next, according to the flowchart of FIG.
The operation of setting the feedback control constant will be described.

In step 31, the operating state is read from the engine speed Ne, the fuel injection amount Qsol, and the like. In step 32, the delay Itd from the command of the fuel injection timing control to the actual operation of the timing control valve 3 is calculated.

The delay Itd is obtained by adding the delay Itdne corresponding to the engine speed Ne in FIG. 10 and the delay Itdqf corresponding to the fuel injection amount (load) shown in FIG. . In this case, the delay amount increases as the rotation speed Ne increases, and increases as the injection amount Qsol increases.

At step 33, the actual injection timing Itist obtained as described above is read, and at step 34, the actual static injection timing Itists is calculated by adding the delay Itd to this Iist. Note that the actual injection timing Itist with respect to the actual static injection timing Itists is referred to as a real dynamic injection timing.

Next, at step 35, the current stroke amount Tcvs of the timing control valve 3 is obtained.
To Tcvs = (Itists-ITSET #) / DE
It is calculated as G_P_MM #. However, here ITS
ET # is the pump set angle, DEG_P_MM # is TCM
(Timing control valve) means the amount of advance angle per 1 mm stroke.

In step 36, the maximum stroke amount Tcv of the timing control valve 3 is obtained from a table as shown in FIG. 12 based on the engine speed Ne at that time.
Search for sm.

Then, in step 37, these Tcv
Using s and Tcvsm, a correction gain Gpid of the feedback control constant as shown in FIG. 13 is searched. The correction gain Gpid takes a larger value as the current stroke Tcvs with respect to the maximum stroke Tcvsm of the timing control valve 3 becomes smaller, and becomes smaller as the current stroke approaches the maximum stroke, that is, as the stroke increases.

FIG. 14 shows the timing control valve 3.
The stroke of the timing control valve 3 for the same control duty increases as the pump speed (engine speed / 2) increases, but as the control duty increases, the stroke of the timing control valve 3 increases. , The stroke increases relatively. In this case, as the control duty increases, the relative change amount of the stroke of the timing control valve 3 increases. In other words, the sensitivity to the duty increases as the stroke increases.

Therefore, as the correction gain Gpid of the feedback control constant, in a region where the stroke of the timing control valve 3 is large, it is necessary to reduce the correction gain in order to prevent excessive response due to excessive sensitivity.

In step 38, the G thus determined
The feedback control constants Kp, Ki, and Kd are obtained by multiplying pid by the basic value of the feedback control constant. The basic value of the feedback control constant is KPB of the proportional coefficient basic value and KI of the integral coefficient basic value, which are obtained according to the current control value and the feedback value, respectively.
B, KDB of differential coefficient basic values, and Gpid
, Kp, Ki, and Kd are calculated.

Next, the operation will be described.

The controller 5 operates at that time,
In other words, the injection timing obtained based on the engine speed, fuel injection amount, etc. is corrected based on the cooling water temperature at that time,
The target fuel injection timing Itsol is calculated. Also,
The injection timing detected from the actual lift state of the fuel injection nozzle 4 is corrected in consideration of the detection delay of the lift sensor 6, and the actual dynamic injection timing Itist is calculated.

Then, the actual dynamic injection timing Itist
Then, the actual static injection timing Itists is obtained by adding the delay of the operation response of the timing control valve 3 to this, and the current stroke position of the timing control valve 3 is calculated based on this value.

From the relationship between the current stroke position and the maximum stroke position of the timing control valve 3 determined according to the rotation speed, the feedback control constant K
A correction gain Gpid for p, Ki, and Kd is calculated, and the feedback control constant is corrected based on the correction gain.

Using the feedback control constants Kp, Ki, and Kd thus obtained, the target injection timing Itso is performed by ordinary feedback control, that is, PID control.
l and the deviation of the actual injection timing Itist,
Control duty value T of timing control valve 3
Calculate CVduty.

The stroke position of the timing control valve 3 is determined by the control duty. The stroke position increases as the control duty increases, and the pressure applied to the timer piston 2 changes accordingly.
The position of the timer piston 2 changes, and the fuel injection timing is controlled.

The stroke sensitivity of the timing control valve 3 increases as the control duty increases.
Therefore, the feedback control constant correction gain Gp
By making id smaller as the stroke position of the timing control valve 3 becomes larger, excessive response is suppressed, and in this way, the target fuel can be stably always obtained regardless of transient or steady state in all control regions. It is possible to precisely control the injection timing. As a result, even if there is a difference between the individual fuel injection pumps, a change with time, etc., it is possible to always maintain good exhaust emission.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a calculation operation of a control duty of a timing control valve.

FIG. 3 is a flowchart illustrating a calculation operation of a target fuel injection timing.

FIG. 4 is a characteristic diagram showing a correction characteristic of a fuel injection timing at the time of starting in relation to a water temperature.

FIG. 5 is a characteristic diagram showing a correction characteristic of a fuel injection timing after warm-up in relation to a water temperature.

FIG. 6 is a characteristic diagram showing a setting characteristic of a target injection timing by a relationship between an engine speed and a fuel injection amount.

FIG. 7 is a flowchart showing an operation for calculating an actual injection timing.

FIG. 8 is a characteristic diagram showing an injection timing detection delay characteristic in a relationship between an engine speed and a fuel injection amount.

FIG. 9 is a flowchart illustrating an operation of calculating a feedback control constant.

FIG. 10 is a characteristic diagram showing injection timing control delay characteristics in relation to engine speed.

FIG. 11 is a characteristic diagram showing an injection timing control delay characteristic in relation to a fuel injection amount.

FIG. 12 is a characteristic diagram showing a characteristic of a maximum stroke amount of the timing control valve in relation to an engine speed.

FIG. 13 is a characteristic diagram showing a correction characteristic of a feedback control constant in relation to a stroke ratio of a timing control valve.

FIG. 14 is a characteristic diagram showing an advance characteristic of a fuel injection timing by a timing control valve.

FIG. 15 is a configuration diagram showing the configuration of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection pump 2 Timer piston 3 Timing control valve 4 Fuel injection valve 5 Controller 6 Lift sensor 7 Speed sensor 8 Accelerator opening sensor 9 Engine coolant temperature sensor

Claims (6)

[Claims] A means for detecting an operating state of the engine; a means for setting a target fuel injection timing according to the engine operating state; a timing control valve for controlling the fuel injection timing; A fuel injection timing control device for an internal combustion engine, comprising: means for calculating; and means for driving a timing control valve based on a deviation between a target injection timing and an actual injection timing to feedback-control the fuel injection timing. A fuel injection timing control device for an internal combustion engine, comprising: means for calculating a stroke amount of a valve; and correction means for changing a constant of the feedback control means according to the stroke amount. 2. The apparatus according to claim 1, wherein said correcting means includes means for calculating a maximum stroke amount of the timing control valve, and means for calculating a current stroke amount, and changes a feedback control constant according to a ratio between these. 3. A fuel injection timing control device for an internal combustion engine according to claim 1. 3. The fuel injection timing of an internal combustion engine according to claim 1, wherein the correction means reduces the correction amount of the feedback control constant as the ratio of the current stroke amount to the maximum stroke amount of the timing control valve increases. Control device. 4. The correction means includes means for calculating a delay amount from when the operation of the timing control valve is commanded to when the timing control valve is actually operated in accordance with the engine operating state, and a timing control valve in accordance with the delay amount. The fuel injection timing control device for an internal combustion engine according to any one of claims 1 to 3, further comprising means for correcting a calculated value of the stroke amount. 5. The target injection timing setting means includes means for calculating a target injection timing according to an engine operating state, and means for correcting the target injection timing according to an engine cooling water temperature. The fuel injection timing control device for an internal combustion engine according to any one of the above. 6. The means for calculating the injection timing comprises means for detecting the actual injection timing and means for calculating the detection delay amount of the actual injection timing based on the operating state. The fuel injection timing control device for an internal combustion engine according to any one of claims 1 to 5, which calculates an injection timing of the internal combustion engine.