JPH08312417A - Diesel engine starting fuel injection control device and method - Google Patents

Abstract

(57) [Abstract] [Purpose] Diesel engine start-time fuel injection control device for preventing white smoke and the like caused by unburned fuel when starting a diesel engine whose fuel injection is electronically controlled And providing a method. [Structure] The fuel cut time from the beginning of cranking to improve the startability at low temperature is set taking into consideration not only the engine cooling water temperature but also the intake air temperature, and is set in advance in the controller as a fuel cut time map. Set it. At the time of starting, the fuel cut time is obtained from the map from the time when the key switch is ON (step 1) to the time when the starter is ON (step 5) (step 4). Then, after the fuel cut time has elapsed, fuel injection from the injection pump is started (step 10). The intake air temperature at the start is equal to the outside air temperature, but the fuel cut time is set in consideration of the outside air temperature as well, so even if the outside air temperature is different, the amount of unburned fuel discharged will be less,
Less white smoke is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection at the time of starting a diesel engine for preventing white smoke and the like resulting from unburned fuel when starting a diesel engine whose fuel injection is electronically controlled. The present invention relates to a control device and method.

[0002]

2. Description of the Related Art In a diesel engine vehicle that employs electronically controlled fuel injection, the amount and timing of fuel injection into the engine are controlled by a controller mainly composed of a computer. The control of the injection amount is performed according to the various control maps stored in the controller in advance. The types of control maps to be stored are roughly classified into a start-time injection amount control map applied at the start and a normal-time injection amount control map applied after the start. The content of the map is appropriately determined depending on what the starting characteristics are and what the traveling characteristics are.

FIG. 5 shows an example of a starting injection amount control map. When the engine cooling water temperature at the time of starting is low, the injection amount (Q) is larger than when it is high. In Figure 6,
An example of a normal time injection amount control map is shown. K ₁ ~K ₄ is the accelerator opening _{(K 1> K 2> K} 3> K 4). The injection amount (Q) is determined by the engine speed (N) and the accelerator opening degree at that time. Even at the same engine speed, the injection amount (Q) is set to be larger as the accelerator opening is larger (that is, the accelerator pedal depression amount is larger).

By the way, the state of the diesel engine at the time of starting is not always in a good state in which the injected fuel burns. When the condition is not good, even if the injection amount calculated by the start-time injection amount control map is injected just because the cranking by the starter is started, the combustion is not sufficiently performed and the startability is not good. Then, the unburned fuel was discharged to the outside in the form of white smoke or the like. Therefore, the following techniques have been conventionally proposed in order to improve the startability and prevent white smoke from being emitted by allowing sufficient combustion.

The technique proposed in Japanese Patent Laid-Open No. 59-180041 detects the cooling water temperature of a diesel engine, and when it is above a predetermined temperature, it is injected with cranking, but when it is below a predetermined temperature. Is a technique in which injection is performed after a set time. That is, when the temperature of the combustion chamber of the engine is low, the fuel is cut during the set time and only cranking is performed to raise the temperature of the combustion chamber, and when the temperature rises, fuel injection is started. Is.

[0006]

[Problems to be Solved by the Invention]

(Problem) In the above-mentioned conventional technique, when the outside air temperature is lower than the engine cooling water temperature, combustion is not sufficiently performed, so that the startability is also poor and unburned fuel becomes white smoke or the like. There was a problem of being discharged.

(Explanation of Problems) The outside air temperature is also the intake air temperature at the time of starting. However, even if the engine cooling water temperature is the same, if the intake air temperature is different, the ease of combustion differs. For example, when the intake air of -10 ° C enters the combustion chamber where the engine cooling water temperature is -10 ° C,
It is more difficult to burn when the intake air comes in and when. This is because the temperature of the combustion chamber is reduced all at once by the intake air taken in.

As an example of the case where the intake air of -10 ° C is introduced into the combustion chamber of which the engine cooling water temperature is -10 ° C, it is attempted to start after stopping for a long time at a temperature of -10 ° C. The case may be mentioned. Engine cooling water temperature is -1
As an example of the case where the intake air of -20 ° C enters into the combustion chamber of 0 ° C, when the engine is temporarily stopped at a place where the temperature is -20 ° C due to a stop etc.
The case where the engine cooling water temperature has dropped to −10 ° C. can be mentioned.

By the way, in the above-mentioned prior art, the fuel cut time is set only according to the engine cooling water temperature (-10 ° C. in the above example).
The fuel cut time is the same. Therefore, in the case of, it may start successfully and white smoke may decrease,
In the case of, the startability is poor, and white smoke is often present. An object of the present invention is to solve such a problem.

[0010]

In order to solve the above problems, in a diesel engine starting fuel injection control device of the present invention, an injection pump, a starter switch, an engine speed sensor, an intake air temperature sensor, and an engine cooling. It has a water temperature sensor and a fuel cut time map that defines the fuel cut time from the beginning of cranking so that combustion is promoted in consideration of the intake air temperature and engine cooling water temperature, and injection is started after the fuel cut time has elapsed. To control the injection pump, and a starter switch O
A timer for counting the fuel cut time from N hours is provided.

Further, in the fuel injection control method for starting a diesel engine of the present invention, a fuel cut time map that defines the fuel cut time from the beginning of cranking so that combustion is promoted in consideration of the intake air temperature and the engine cooling water temperature. Thus, the fuel cut time is obtained from the time when the key switch is turned on to the time when the starter is turned on, and after the fuel cut time has elapsed from the beginning of cranking, fuel injection from the injection pump is started.

[0012]

[Operation] When the diesel engine with electronically controlled fuel injection is started, the engine cooling water temperature detected by the engine cooling water temperature sensor and the intake air temperature detected by the intake air temperature sensor are applied to a predetermined fuel cut time map. , Find the fuel cut time from the beginning of cranking. Then, after that time has elapsed, fuel injection from the injection pump is started. By cranking with the fuel cut, the air in the combustion chamber is compressed, the temperature in the combustion chamber rises, and the internal pressure of the injection pump rises, so that the advance amount required for the start advance is obtained. Therefore, the conditions for easy burning are set. In the present invention, the fuel cut time map is created in consideration of not only the engine cooling water temperature but also the intake air temperature so that combustion in the engine is promoted, so even when the outside air temperature is different, The amount of unburned fuel that is discharged is reduced, and the generation of white smoke is reduced.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a block diagram showing the fuel injection control device for starting the diesel engine of the present invention. 1 is an injection pump, 2 is an engine speed sensor, 3 is a fuel pipe,
4 is an electric governor, 5 is a fuel cut valve, 6
Is a timing control valve, 7 is a fuel pipe, 8
Is a controller, 8-1 is a timer, 9 is an accelerator opening sensor, 10 is a starter switch, 11 is an engine cooling water temperature sensor, 12 is an intake temperature sensor, 13 is an intake pipe, 14 is an exhaust gas recirculation pipe, 15 is an injection nozzle, 16 is an exhaust pipe, 17 is a diesel engine, and 18 is a turbocharger.

As the engine, a diesel engine with a turbocharger is shown, but of course, a diesel engine without it is also applicable. Fuel is supplied from the fuel pipe 3 to the injection pump 1, and the fuel pipe 7
Is sent to the injection nozzle 15 and is injected into the diesel engine 17. Electric governor 4
The injection timing is controlled by the timing control valve 6.

The control signals to the electric governor 4 and the timing control valve 6 are based on signals from various sensors and the injection amount control map preset in the controller 8 (see FIGS. 5 and 6). Generated at 8. When it is desired to stop the fuel injection, a control signal is sent to the fuel cut valve 5. The starter switch 10 is a switch for turning on a starter (not shown) for cranking the engine, and the controller 8 is supplied with a signal notifying that it has been turned on.

A timer 8-1 is set in the controller 8. This may be provided outside the controller 8. Further, in the controller 8, in addition to the above-mentioned injection amount control map, a fuel cut time map as shown in FIG. 3 is set in advance. This map is a map in which the length of the fuel cut time at the initial stage of cranking is determined in consideration of both the intake air temperature at the time of starting and the engine cooling water temperature so that combustion can be performed well. Having this in the controller 8 is one of the main features of the device of the present invention.

In FIG. 3, the horizontal axis represents the engine cooling water temperature (T _W ) and the vertical axis represents the fuel cut time (T). FIG. 3 (a)
Is a map when the intake air temperature is −40 ° C., and FIG.
(B) and (c) are maps when the intake air temperature is -20 ° C and -10 ° C, respectively. For example, the intake air temperature detected by the intake air temperature sensor 12 = −40 ° C., the engine cooling water temperature detected by the engine cooling water temperature sensor 11 = T _W1
In that case, the fuel cut time is calculated as 1 mS from the map of FIG.

FIG. 1 is a flow chart for explaining a fuel injection control method for starting a diesel engine according to the present invention. Step 1: Turn on the key switch. Step 2 ... Checks whether the engine speed detected by the engine speed sensor 2 is zero. If it is not 0, it means that the engine has already been started, so that the routine proceeds to step 12 so that the injection control is performed according to the normal time injection amount control map (FIG. 6). Since this flow chart is repeatedly flown at an extremely short cycle, it may be flown when already started, and in that case, step 12
Proceed to.

Step 3 ... Engine cooling water temperature sensor 11
Engine cooling water temperature detected by the intake air temperature sensor 1
The intake air temperature detected in 2 is read. Step 4 ... Applying them to the fuel cut time map of FIG. 3 to obtain the fuel cut time T. Step 5 ... Read the signal from the starter switch 10 that the starter is ON (starts cranking).
In other words, the controller 8 carries out the processing of steps 2 to 4 between the time when the driver turns on the key switch (step 1) and the time when the starter is turned on.

Step 6 ... Start fuel cut. That is, the controller 8 sends a control signal to the fuel cut valve 5 to stop the injection. Step 7 ... Start time counting by the timer 8-1. Step 8 ... It is checked whether or not the fuel cut time T has elapsed by the timer 8-1. Step 9: When the fuel cut time T has elapsed, a control signal is sent to the fuel cut valve 5 to cancel the fuel cut. That is, the injection is permitted.

Step 10 ... Since the engine is starting, the injection is performed according to the starting injection amount control map (FIG. 5). Step 11 ... Examine whether the engine has reached full explosion (self-rotation). This is done by checking whether the engine speed has reached a predetermined start mode release speed. Step 12 ... When the complete explosion is reached, the starting mode is shifted to the normal mode thereafter, and the injection control is performed according to the normal injection amount control map (FIG. 6).

FIG. 4 is a diagram showing changes in various amounts when the diesel engine is started. The solid curve A shows the change in the case of the present invention, and the chain line B shows the change without the fuel cut time. The horizontal axis of FIG. 4 is all time, and the vertical axis is the engine speed in FIG. 4 (a), the injection pump internal pressure in FIG. 4 (b), and the advance amount in FIG. 4 (c).
FIG. 4D shows the injection amount, and FIG. 4E shows the white smoke amount.

Time t ₀ is the time when the starter is turned on and cranking is started (see step 5 in FIG. 1). The engine speed in FIG. 4 (a) is low during cranking, but suddenly increases when the engine speed is removed. As shown in FIG. 4D, the fuel injection is performed from time t ₀ as indicated by the curve B when the fuel cut time is not provided. However, in the case of the present invention, t ₁ after the fuel cut time T has elapsed from the cranking start time t ₀ as shown by the curve b
Started at. The conventional example described in the section of the prior art (Japanese Patent Laid-Open No.
59-180041, etc.), the fuel cut time is also provided, but the length is determined by considering only the engine cooling water temperature, and is different from the length of the present invention.

The fuel cut is to stop the injection from the fuel pipe 7 of the injection pump 1 to cut the fuel to the diesel engine 17, but if the cranking is performed while the injection is stopped, the internal combustion engine The temperature of the air is raised by adiabatic compression, and the temperature of the engine cooling water is also raised by the temperature. Therefore, the fuel becomes easy to burn.

The injection pump 1 is driven by the engine, but if it is driven while the injection is stopped, the pressure is accumulated, so that the internal pressure of the injection pump is higher than that during the injection. In FIG. 4 (b), curve A of the present invention is located above curve B where the injection is not stopped, which indicates that. By increasing the internal pressure of the injection pump, the following advantages occur.

The first advantage is that in the electronically controlled fuel injection device, the internal pressure of the injection pump is related to determining the advance amount (injection timing). The larger the internal pressure, the more the instruction is given. The point is that they will advance. The advance amount in the case where the fuel cut time is not provided is as shown by the curve B in FIG. 4C, but the advance amount according to the present invention is as shown by the curve A. Generally, at the time of starting, the advance amount as shown by the curve C in FIG. 4C is desired as the ideal advance amount (target advance amount). But,
It becomes closer to the target advance amount. The second advantage is that when the injection is started, atomization of the fuel is favorably performed. As the fuel is injected at a higher pressure, the fuel is atomized, and it becomes easier to combust in the engine.

As described above, some favorable conditions for promoting combustion are set, and they act synergistically to facilitate combustion, so that less unburned fuel is discharged. Therefore,
As shown in FIG. 4E, the amount of white smoke (curve B) generated in the present invention is smaller than that in the case where the fuel cut time is not provided (curve B).

[0028]

As described above, according to the fuel injection control device and method for starting a diesel engine of the present invention, the fuel cut time from the beginning of cranking is taken into consideration not only the engine cooling water temperature but also the intake air temperature. Since the time is set such that combustion is promoted in the engine, the amount of unburned fuel that is discharged is reduced and the generation of white smoke and the like is reduced even when the outside air temperature is different.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating a fuel injection control method for starting a diesel engine according to the present invention.

FIG. 2 is a block diagram showing a fuel injection control device for starting a diesel engine according to the present invention.

FIG. 3 is a diagram showing a fuel cut time map.

FIG. 4 is a diagram showing changes in various amounts when starting a diesel engine.

FIG. 5 is a diagram showing a starting injection amount control map.

FIG. 6 is a diagram showing a normal injection amount control map.

[Explanation of symbols]

1 ... Injection pump, 2 ... Engine speed sensor, 3 ... Fuel pipe, 4 ... Electric governor, 5 ... Fuel cut valve, 6 ... Timing control valve, 7 ... Fuel pipe, 8 ... Controller, 8-1 ... Timer, 9 ... accelerator opening sensor, 10 ... starter switch, 11 ... engine cooling water temperature sensor, 12 ... intake air temperature sensor, 13 ... intake pipe, 14 ... exhaust gas recirculation pipe, 15 ... injection nozzle, 16 ... exhaust pipe, 17 ... diesel engine, 18 ... Turbocharger

Front page continuation (72) Inventor Tadashi Uchiyama 8 No. 8 in Fujisawa City Shelf In Isuzu Motors Co., Ltd. Fujisawa Plant (72) Inventor Takashi Makimoto No. 8 in Fujisawa City Shelf No. 8 Isawa Motor Co., Ltd. in Fujisawa Plant (72) Inventor Imai Junichi Fujisawa City, 8 shelves Isuzu Motors Co., Ltd. Fujisawa factory (72) Inventor Koichi Kuroda 8, Fujisawa city Shelfs Isuzu Motors Co., Ltd. Fujisawa factory

Claims (2)

[Claims] 1. An injection pump, a starter switch, an engine speed sensor, an intake air temperature sensor, an engine cooling water temperature sensor, and an initial cranking so as to promote combustion taking into consideration the intake air temperature and the engine cooling water temperature. And a controller for controlling the injection pump to start injection after the fuel cut time elapses, and a timer for measuring the fuel cut time from the starter switch ON time. A fuel injection control device for starting a diesel engine, comprising: 2. A fuel cut time map that defines the fuel cut time from the beginning of cranking so that combustion is promoted in consideration of the intake air temperature and the engine cooling water temperature, from the time when the key switch is turned on to the time when the starter is turned on. A method for controlling fuel injection at the time of starting a diesel engine, characterized in that the fuel cut time is calculated in step 1, and fuel injection from the injection pump is started after the fuel cut time has elapsed from the beginning of cranking.