JPH10103143A - Injection timing control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To install an engine advance angle amount properly and reduce an engine noise by providing an initial value set means, set by an engine water temperature, for finding out an initial value for correcting an entire timing amount by adding to a basic timing and an initial value reduction means for reducing the initial value along with a time. SOLUTION: Usually, in a control means 20, a basic injection timing used at the transfer time to the more stable operation state than a prescribed number of rotation after idling operation is set and just after starting, the basic timing is set by preparing plural timing maps by the sum of the number of rotation of an engine and the advance angle correction amount by the timing and water temperature calculated by a load. In an idling timing, in an initial set means 21, the initial value added to the basic timing and the adding time are calculated and set based on based on the engine the engine water temperature just after starting. In the initial value reduction means 22, the generation of an engine noise is prevented by setting a reduction state based on the engine water temperature by the initial value set by the initial value set means 21 and the correction adding time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection timing control device for a diesel engine, and more particularly to an injection timing control device for a diesel engine that optimally controls injection timing immediately after starting.

[0002]

2. Description of the Related Art Conventionally, injection timing control of a diesel engine is divided into a timing control at the time of starting and a timing control at a normal time, and as shown in a flowchart of FIG. 5, when the engine speed exceeds a predetermined value. Alternatively, when the starter switch shifts from on to off, the control shifts from the start timing control to the normal timing control. The normal timing control includes the following two methods. That is, 1. A required timing advance value is obtained from a timing map using the engine speed Ne and the load as variables, and the advance value obtained by correcting the advance value with the engine water temperature is used. 2. A plurality of timing maps for each engine water temperature using the engine speed and the load as variables are prepared, and a map corresponding to the water temperature is switched to obtain a required advance value.

However, immediately after the starter switch shifts from on to off, in other words, until the engine shifts to the idling immediately after the start and the idling is completed, the timing advance by the engine water temperature plays a leading role in many cases. Under the circumstances, timing advance and increase in the number of revolutions during idling have been the main necessary means for improving idle stability especially when the engine water temperature is low in cold regions or winter mornings, etc. Increasing the advance value helps to improve idle stability, but on the other hand, there is a problem that noise, especially knock noise, increases.Idle stability and noise generation problems until idling, which directly affects the level of water temperature, are terminated. There is a reciprocal relationship.

Further, in order to cope with a delay until the ignition of the fuel immediately after the start of the engine, especially at a low temperature, the ignition timing is added to the timing advance value at the time of idling, and the timing of the injection timing immediately after the start is started. Is controlled to be more advanced to the advance side than the required value, and there is a problem that an over-advance angle leads to an increase in knock sound. Regarding the above problem, a countermeasure is disclosed in Japanese Patent Publication No. 5-26942. Such a technique, when performing feedback control of the injection timing according to the deviation between the target ignition timing determined based on the engine load and the engine speed and the actual ignition timing detected by using the ignition timing sensor, at least immediately after the start-up The advance angle of the injection timing is limited by the angle limit value. More specifically, as shown in FIG. 6, during the start when the starter is on, the start is started by the advance angle limit value Dmin, and the starter switch is turned off from on. Immediately after the shift, in other words, immediately after the start, the advance limit value Dmin is limited by the control duty ratio, and the advance limit value Dmin is gradually limited from the maximum value of 20% to 0% to control the injection timing. Thus, the injection timing does not become excessively advanced due to the ignition delay immediately after the start, and the diesel knock does not occur.

[0005] The control duty ratio indicates the value of the control duty ratio by the timing control valve TCV, and the control duty ratio is advanced as the control duty ratio is smaller. That is, the timing control valve is
By opening the valve, the fuel in the high-pressure chamber of the timer piston can be released to the low-pressure side via the bypass, and the injection timing can be delayed. The relief flow rate to the low pressure side is adjusted by the duty ratio given to the timing control valve. Note that the duty ratio of the TCV is an on-time per fixed time. That is, when the duty ratio is 100%, the timing control valve is in the fully open position and the advance angle is "0", and when it is 0%, the timing control valve is in the fully closed position and is the advance limit value Dmin.

[0006]

However, this technique has the following features: (1) Since the control is performed using an ignition timing sensor, it is usually necessary to separately provide an ignition timing sensor which is not an essential item for an electronic control engine. 2. Timing after starting The advance value is gradually reduced from the maximum value of 20% immediately after the start, but the advance value does not always need to be constantly advanced to 20% of the maximum value. As the water temperature increases, the advance angle value also decreases. As a matter of fact, in the case of control in which the advance angle is constantly increased to the maximum value of 20%, a knock sound is generated. 3. The advance angle limit value after the start and the advance angle target value calculated from the load and the rotational speed are always compared and the larger value is adopted for the control. Generally, the combustion chamber temperature is low immediately after the engine is started. Since the ignition delay is large, it is usually preferable to perform control by adding the delay to a target value calculated from the load and the number of revolutions, which is problematic in this respect. Therefore, such technology does not always satisfactorily solve the problem of injection timing control immediately after starting.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and aims to cope with combustion instability that is likely to be unstable immediately after starting by adding an appropriate correction to a basic injection timing determined based on an engine load and an engine speed. It is an object of the present invention to provide a diesel engine injection timing control device in which the timing is advanced a little, and when the idling ends, the advance is suppressed, noise is prevented, and idle stability immediately after starting is achieved.

[0008]

SUMMARY OF THE INVENTION Therefore, the invention according to claim 1 of the present invention is directed to a diesel engine which sets an optimum injection timing by controlling a timing advance value based on an engine speed and an engine water temperature immediately after starting. In the injection timing control device, immediately after the start, the normal control means for setting the basic timing by the load and the engine speed, and set by the engine water temperature detected by the water temperature sensor,
An initial value setting means for obtaining an initial value for correcting the total timing amount added to the basic timing, and an initial value reducing means for decreasing the initial value with time are provided.

According to a second aspect of the present invention, the initial value setting means is specified, and the initial value setting means sets the interval time and the amount of decrease in a substantially stepwise manner in accordance with the engine coolant temperature. It consists of.

The invention according to claim 3 also specifies the initial value setting means, and the initial value reducing means sets a time until the initial value becomes zero according to the engine water temperature, and sets the time to the set time. It is constituted by continuous reduction means for reducing the initial value substantially continuously based on this.

According to the first aspect of the present invention, when the improvement of idle stability at low temperatures cannot be solved only by means such as an advance angle and an increase in idle speed, particularly, combustion becomes unstable and idle becomes unstable easily. In order to advance the timing more in the part, at the time of idling immediately after the start, set the basic injection timing timing by normal control and add it on top of it, add the initial value according to the engine water temperature, and immediately after the start As the time elapses, the total amount of timing added with the initial value is reduced with the passage of time, so as to correspond to a change in the water temperature during idling. Therefore, as the engine water temperature is warmed up by idling, the above-mentioned additional initial value is reduced to control the optimal injection timing. In particular, in the present invention, since the setting of the initial value is set by a detection signal from a water temperature sensor, there is no need to separately provide an ignition timing sensor, which is cost effective.

According to the second aspect of the present invention, since the additional initial value is reduced in a stepwise manner based on the engine water temperature, it is possible to appropriately cope with a rise in the water temperature due to a warm-up operation during idling.

According to a third aspect of the present invention, since the additional initial value is reduced in a continuous provisional manner based on the engine water temperature, the warm-up operation state can be accurately performed by a calculation using the water temperature change as a function. Can be handled flexibly.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described together with the illustrated example. However, unless otherwise specified, the dimensions, shapes, relative positions, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent. FIG.
FIG. 2 is a schematic diagram of an injection timing control system for a diesel engine according to the present invention, FIG. 2 is a diagram of an injection timing control system at the time of idling of FIG. 1, and FIG. 3 is a diagram showing an operation concept of FIG.

As shown in FIG. 1, the injection timing control apparatus for a diesel engine according to the present invention comprises an electronic control distribution type fuel injection pump 10 and an engine 11 (only a part of the cylinder is shown).
It comprises an ECU (control unit) 12. On the engine 11 side, a water temperature sensor 12a provided in a cylinder block for detecting engine coolant temperature, a crank angle sensor 12b for detecting a crank angle reference position, an intake pressure sensor 13a provided downstream of an intake throttle valve, and an air cleaner An intake air temperature sensor 13b for detecting the temperature of intake air provided downstream is provided, and a rotation speed sensor 14a and a timer piston position sensor 14b for detecting the position of the timer piston 15 are provided on the fuel injection pump 10 side. And
An accelerator position sensor 13 for detecting an accelerator opening and a starter switch 18 are provided on an accelerator side or a driver's seat side (not shown). These detection signals are input to the ECU 12.

The ECU performs necessary arithmetic processing based on the signals indicating these operating states to control the operation of the timing control valve 16 of the fuel injection pump 10 and to control the timing advance value of the fuel injection timing. ing. The timing control valve 16 is a high-speed solenoid valve that is opened and closed by an electric signal subjected to duty control.
When the fuel pressure in the high-pressure chamber 15a of the timer piston is adjusted by the opening / closing control and leaks toward the low-pressure chamber, the position of the timer piston is displaced toward the retard side, and the slide pin 15b tilts left and right. The tilting controls the lift timing of the plunger 17, so that the fuel injection timing from each fuel nozzle is advanced or delayed.

FIG. 2 is a diagram showing an injection timing control system during warm-up operation in the diesel engine injection timing control apparatus of the present invention shown in FIG. As shown in FIG.
In the case of No. 2, immediately after the starter switch 18 is turned on from off, the accelerator opening or the sensor
a from the load information based on each signal of the intake pressure and the sensor 14a
The normal control means 20 for setting the basic timing based on the engine speed and the engine water temperature detected by the water temperature sensor 12a, which is added to the basic timing to obtain an initial value for correcting the total timing amount. Value setting means 21 and an initial value reducing means 22 for reducing the initial value with time,
In addition to performing predetermined arithmetic processing described later, injection timing control of the diesel engine is performed via the timing control valve 16 in FIG. 1 based on the total timing amount signal.

That is, the normal control means 20 sets the basic injection timing to be used when shifting to the stable operation state at a predetermined rotation speed or more after the idling operation, and immediately after the start, the engine rotation speed Ne and the load. The basic timing or a plurality of timing maps using the engine speed and the load as variables are prepared according to the sum of the timing calculated from the map using the variable and the advance correction amount based on the water temperature, and the corresponding basic timing is set according to the water temperature. .

The initial value setting means 21 calculates and sets an initial value to be added to the basic timing immediately after the start and an additional time at the idling time based on the engine coolant temperature. The initial value garden means 22 selects one of a stepwise reduction and a continuous reduction as the form of temporal reduction based on the initial value set by the initial value setting means 21 and the correction addition time, and reduces the reduction. The configuration is set based on the engine water temperature. For example, if a stepwise reduction mode is set, the interval time and the amount of reduction are set in a substantially stepwise manner according to the engine water temperature, and if a continuous reduction mode is selected, the initial value becomes zero according to the engine water temperature. , And the initial value is continuously reduced by a predetermined function based on the set time.

The operation concept of FIG. 2 is shown in FIG. 3, and its outline will be described below. FIG. 6A is a diagram showing a state of correction at the time of idling by a post-start correction amount having a stepwise reduction form, and an advance value is set to an initial value (S−W) from a start control end time R to a basic timing W. ) Is added to the total timing value S, the advance angle value is reduced stepwise from the total timing value S based on the interval time t and the decrease amount V, and the correction after the start is performed when the basic timing point W is reached. The control shifts to the normal control. The initial value (S-W), the interval time t, and the amount of decrease V are set so that optimal timing control can be obtained based on the passage of time immediately after the start and the engine water temperature that changes depending on environmental conditions. .

FIG. 3 (B) is a graph showing a control situation immediately after the start having the continuous reduction mode. In FIG. The value is decreased to the added all timing values S, and is shifted from the all timing values S at the time of correction after starting, and based on a calculated value that is calculated based on a correction time T until the initial value becomes zero according to the engine coolant temperature. The lead angle is reduced linearly or quadratically, in other words, in a continuous music (straight line),
At the basic timing W, the correction control immediately after the start is completed, and the control shifts to the normal control. The above correction function has an initial value (S−
It is determined by the engine coolant temperature together with W) and the correction time T, and the function formula may be changed according to the elapsed time. In any case, the optimal timing control is obtained.

FIG. 4 shows various data used in the embodiment. FIG. 7A shows the initial value (S-W) with respect to the engine water temperature. As understood from the figure, the lower the engine water temperature, the larger the initial value (S-W) is set, and the lower the engine water temperature. At 55 ° C. or higher, no correction control is performed. FIG. 7B shows an interval time t with respect to the engine water temperature, and the engine water temperature is 10
The interval time t is constant until about 20 ° C., but thereafter increases to about 20 ° C.
The interval time t is reduced at the point in time when the value exceeds.

FIG. 4C shows the amount of decrease V with respect to the engine water temperature. As can be understood from the figure, the amount of decrease V is small until the engine water temperature reaches about 10 ° C., in other words, it gradually decreases. However, when the engine water temperature exceeds 10 ° C., the decrease V also increases proportionally, and when it exceeds approximately 40 ° C., the decrease V stabilizes to a high value. FIG. 3D shows a correction time t (calculated value) for the engine water temperature. As a result, the correction time becomes shorter as the engine water temperature becomes higher.

Therefore, in order to stabilize the engine immediately after the start, a. When the engine coolant temperature is low, the initial value is large, the amount of decrease is small, and it is necessary to slowly decrease it. b, When the water temperature is between 10 ° C. and 35 ° C., it is not necessary to change the advance angle value so much. c, the idling operation ends at a water temperature of 40 ° C., and the control shifts to the normal control. The four graphs are mapped and incorporated in the ECU 12, and used as arithmetic means for the initial value setting means 21 and the initial value reducing means 22. According to the present embodiment, the fluctuation of the engine rotation immediately after the start at -23 ° C. is approximately 400 rpm before correction and 40 rpm.
mp-p could be improved.

[0025]

As described above, according to the present invention, generation of engine noise can be prevented and idle stability can be improved by increasing the timing advance amount in accordance with the engine water temperature immediately after starting.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a diesel engine injection timing control device of the present invention.

FIG. 2 is an injection timing control system diagram during the idling operation of FIG.

3A and 3B are graphs showing the operation concept of FIG. 2, in which FIG. 3A shows a stepwise reduction mode and FIG. 3B shows a continuous reduction mode.

FIG. 4 shows various data used in the embodiment. (A) shows an initial value (advance angle) with respect to the engine water temperature, (B) shows an interval time with respect to the engine water temperature, (C) shows a decrease amount with respect to the engine water temperature, and (D) Shows a correction time t for the engine water temperature.

FIG. 5 is a diagram showing a state of timing control in the related art.

FIG. 6 is a diagram showing a conventional timing control situation immediately after starting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fuel injection pump 11 Engine 12 ECU 12a Water temperature sensor 12b Crank angle sensor 13 Accelerator position sensor 13a Intake pressure sensor 14a Revolution speed sensor 20 Normal control means 21 Initial value setting means 22 Initial value reducing means

Claims (3)

[Claims] An injection timing control device for a diesel engine for setting an optimum injection timing by controlling a timing advance value based on an engine speed and an engine water temperature immediately after starting, wherein a basic timing based on a load and an engine speed immediately after starting. Normal control means for setting an initial water value which is set based on the engine water temperature detected by a water temperature sensor, and obtains an initial value for correcting the total timing amount added to the basic timing, and setting the initial value to time. An injection timing control device for a diesel engine, comprising: an initial value reducing means for decreasing the same. 2. An injection timing control device for a diesel engine according to claim 1, wherein said initial value setting means is a stepwise reducing means for setting an interval time and a decreasing amount in a substantially stepwise manner according to the engine coolant temperature. 3. The continuous value reducing means for setting a time until the initial value becomes zero according to the engine coolant temperature and reducing the initial value substantially continuously based on the set time. The injection timing control device for a diesel engine according to claim 1.