JPH06101531A - Electronically controlled injection system for internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress generation of white smoke and to separate a starting injection quantity pattern from a normal injection quantity pattern so as to enhance starting performance as well as drivability by determining the starting injection quantity pattern in accordance with false throttle opening which is based on engine water temperature. CONSTITUTION:In an internal combustion engine 1, injections 2 for injecting fuel are disposed in each cylinder and are on-off controlled by solenoid valves 3. The injectors 2 are each connected to a common rail 4, which is common to the cylinders, and pressure is kept at a predetermined high value by a discharge control unit 10. Each of the solenoid valves 3 and the discharge control unit 10 are controlled by ECU 11 in accordance with detection signals from driving condition sensors 12, 13, 15; in this case, the starting/normal injection control means 16 of the ECU 11 determine a starting injection quantity pattern in accordance with false throttle opening which is based on water temperature, and also determine a normal injection quantity pattern in accordance with the greater of the false and actual throttle opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improving low temperature startability of an electronically controlled injection system for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, a method of controlling a fuel injection amount of a diesel engine during cold weather has been proposed in Japanese Patent Laid-Open No. 58-85331. The content of the control is to increase the injection amount in the cold state and decrease the injection amount in the warm-up state in the fuel injection amount control method of the diesel engine that controls the injection amount pattern determined by the actual accelerator opening as a parameter. The method of controlling the injection amount by using an accelerator opening degree for control different from the actual accelerator opening degree according to the temperature state at the time of starting is disclosed. This is intended to increase the injection amount at low temperature and improve startability by artificially increasing the accelerator opening.

[0003]

However, in the conventional electronically controlled injection system for the internal combustion engine, the injection amount characteristic (pattern) used in the above case is the injection amount characteristic (rotation speed and Since it is based on the injection amount characteristic obtained from the actual accelerator opening, the following problems occur.

That is, when the engine is cold, the injection amount is simply increased by the pseudo accelerator to shorten the starting time.
The generation of white smoke cannot be prevented. That is, the white smoke is generated when the fuel remains unburned at low temperatures, at the time of starting, at high altitude or when the fuel is poor, that is, when the flame is extinguished in the fuel-lean portion. The components of this white smoke are mainly HC and its oxides. It is necessary to match the injection amount characteristic (pattern) itself when cold. By the way, since the injection amount characteristic is applied also in the normal time, it is necessary to secure the drivability in the normal time. However, it is difficult to realize the injection amount characteristic that tries to establish both of them at the same time. This is because if the drivability performance is to be emphasized, there is a problem that the white smoke at the time of cold must be sacrificed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to propose an electronically controlled injection system for an internal combustion engine, which achieves both improvement of low temperature startability and improvement of drivability during normal operation in view of the above problems.

[0006]

In order to solve the above-mentioned problems, the present invention provides an electronically controlled injection system for an internal combustion engine, which electronically controls the fuel injection amount in an engine through an injection control solenoid valve. The starting injection amount pattern determined by using the pseudo accelerator opening obtained from the water temperature as a parameter, and the normal injection amount pattern determined by using the larger one of the pseudo accelerator opening and the actual accelerator opening as a parameter. If the engine is determined to be in the start mode, control is started with the injection amount determined by the start injection amount pattern based on the pseudo accelerator opening degree, and if the engine speed exceeds a predetermined value, the start is performed. The injection amount pattern is switched to the normal injection amount pattern, the injection amount is controlled, and the pseudo accelerator opening is attenuated with time.

[0007]

According to the electronically controlled injection system for an internal combustion engine of the present invention, since the control is performed by the starting injection amount pattern which is determined by using the pseudo accelerator opening degree obtained from the water temperature of the engine as a parameter, the cranking for cold start is performed. It is possible to suppress the amount of white smoke emitted during the period from the complete explosion until the complete explosion and to freely set the injection amount pattern for shortening the starting time. The normal injection amount pattern is determined by using the larger one of the pseudo accelerator opening amount and the actual accelerator opening amount as a parameter, and when the start mode is determined, the start injection amount is based on the pseudo accelerator opening amount. Start the control with the injection amount determined from the pattern,
When the engine speed exceeds a predetermined value, the starting injection amount pattern is switched to the normal injection amount pattern, so that it can be separated from the injection amount characteristic that satisfies the drivability performance at normal time, so the startability is improved. It is possible to achieve both improvement and drivability performance improvement. By controlling with the injection amount and attenuating the pseudo accelerator opening degree with time, the starting injection amount pattern is smoothly switched to the normal injection amount pattern.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an electronically controlled injection system for an internal combustion engine according to an embodiment of the present invention. The electronically controlled injection system for an internal combustion engine shown in this figure first targets the diesel engine 1. An injector 2 is arranged in the fuel chamber of each cylinder in the engine 1, and fuel injection from the injector 2 to the engine 1 is controlled by turning on and off an injection control solenoid valve 3. The injector 2 is a high pressure accumulator pipe common to each cylinder, a so-called common rail 4.
The fuel in the common rail 4 is injected from the injector 2 into the engine 1 while the injection control solenoid valve 3 is open. Therefore, it is necessary to continuously accumulate a high predetermined pressure corresponding to the fuel injection pressure in the common rail 4, and for that purpose, the high pressure supply pump 7 is connected via the supply pipe 5 and the check valve 6. The high-pressure supply pump 7 reciprocates the plunger by a cam (not shown) that synchronizes the fuel sucked from the fuel tank 8 into the well-known low-pressure supply pump 9 with the rotation of the engine 1 to obtain the required high pressure. The pressure is increased and supplied to the common rail 4, and a discharge amount control device 10 for constantly maintaining the pressure of the common rail 4 at a predetermined high pressure is provided. The operation of the injection control solenoid valve and the discharge amount control device 10 is controlled by a control signal output from an electronic control unit (hereinafter simply referred to as ECU) 11. The ECU 11 receives detection signals from the engine speed sensor 12 and the accelerator opening sensor 13, and also a pressure sensor 14 for detecting the actual common rail pressure and various sensors 1 such as water temperature, intake temperature, and intake pressure.
The ECU 11 to which the input signals from 5 are input determines the operating state of the engine 1 based on these input signals and performs arithmetic processing according to a predetermined program to optimize the injection control solenoid valve 3 and the discharge amount control device 10. Output a control signal. Further, the ECU 11 is provided with a start / normal injection control means 16 to be described later, and a memory (RAM) for storing detection data, control programs, etc. for performing these controls.
(Random Access Memory), ROM (Read Only Memory),
(Not shown), and further not shown A / D converter (Analog to Digital Converter) of each sensor and D / A converter (Digital to Anal
og Converter). Next, the starting / normal injection control means 16 will be described.

FIG. 2 is a diagram showing the structure of the starting / normal injection switching control means of FIG. The starting / normal injection control means 16 shown in this figure comprises a normal injection amount pattern storage means 161. FIG. 3 is a diagram showing a normal injection amount characteristic stored in the normal injection amount pattern storage means of FIG. As shown in this figure,
The normal injection amount pattern storage means 161 stores a known basic injection amount pattern with the engine speed (Ne) and the accelerator opening (ACC (%)) as parameters, and the engine speed data of the engine speed sensor 12 and the accelerator. The accelerator opening data from the opening sensor 13 or a pseudo accelerator opening described later, whichever is larger, is input, and the injection amount corresponding to this input is read. That is, in this normal injection amount pattern, the injection amount decreases as the engine speed increases and the injection amount increases as the accelerator opening increases, with the constant accelerator opening as a parameter.

Further, the starting / normal injection control means 16 comprises a starting injection amount pattern storage means 162. The starting injection amount pattern storage means 162 stores the starting injection characteristics for preventing white smoke at the time of starting and low temperature. FIG. 4 is a diagram showing the starting injection characteristics stored in the starting injection amount pattern storage means of FIG. As shown in the figure, in the starting injection amount pattern storage means 162, the engine speed and the pseudo accelerator opening degree (ACPC (%)) described later are used as parameters, and the injection quantity pattern is the engine rotation speed with respect to a constant pseudo accelerator opening degree. When the number increases, the injection amount once rises and then decreases, and the injection amount increases as the pseudo accelerator opening increases. Compared with the normal injection characteristics shown in FIG. 3, when the engine speed is small, the injection amount is increased, and when the engine speed exceeds a certain value, the decrease of the injection amount is increased with respect to the decrease of the engine speed, and white smoke is generated. Prevent.

Further, the starting / normal injection control means 16 is provided with a pseudo accelerator opening degree generating means 163 for inputting water temperature data from various sensors 15 and calculating a pseudo accelerator opening degree. FIG. 5 is a diagram showing the relationship between engine water temperature and pseudo accelerator opening degree in the pseudo accelerator opening degree generating means of FIG.
As shown in the figure, in the pseudo accelerator opening generation means 163, the pseudo accelerator opening (ACPS (%)) is 0% when the engine water temperature is equal to or higher than the constant temperature T0, and when the temperature is equal to or lower than the temperature T0, the pseudo accelerator is increased as the temperature decreases. The opening is designed to increase.

The starting / normal injection control means 16 is provided with an accelerator opening degree selecting means 164. The accelerator opening degree selection means 164 compares the actual accelerator opening degree (ACC) from the accelerator opening degree sensor 13 with the pseudo accelerator opening degree (ACPS) from the pseudo accelerator opening degree generating means 163, and the larger one is the normal injection amount. It is output to the pattern storage means 161. In the normal injection amount pattern storage means 161, the engine speed (Ne) from the engine speed sensor 12 and the accelerator opening selected by the accelerator opening selection means 164 are input and the normal injection amount is read.

In the starting injection amount pattern storage means 162, the engine speed (Ne) from the engine speed sensor 12 and the pseudo accelerator opening degree (ACPS) from the pseudo accelerator opening degree generating means 163 are input and the start injection is performed. The quantity is read. The start / normal injection control means 16 has an injection switching means 165 that selectively selects the normal injection amount pattern storage means 161 and the start injection amount pattern storage means 162.
It is equipped with. The opening / closing time of the injection control solenoid valve 3 is controlled by the injection amount (Q) read from any selected one.

The starting / normal injection control means 16 causes the injection switching means 165 to operate as the starting injection amount pattern storage means 162.
A starting injection switching determination means 166 for making a determination for switching to the side is provided. The starting injection switching determination means 166 inputs the accelerator opening (ACC) of the accelerator opening sensor 13, and if this accelerator opening = 0%, the injection switching means 16 is provided.
5 is switched to the starting injection amount pattern storage means 162 side.

The starting / normal injection control means 16 comprises a first normal injection switching determination means 167 which makes a determination for switching the injection switching means 165 to the normal injection amount pattern storage means 161 side. The first normal injection switching determination means 1
67 is the engine speed of the engine speed sensor 12 (N
e) and enter the engine speed (Ne
1) Determine if it is above. It is assumed that the engine 1 has reached a complete explosion when the engine speed (Ne) is reached.
When it is determined that this determination condition is satisfied, the injection switching unit 165 is switched from the starting injection amount pattern storage unit 162 to the normal injection amount pattern storage unit 161 side. Further, the pseudo accelerator opening degree generation means 1 is established when the determination condition is satisfied.
At 63, the pseudo accelerator opening (ACPS) decays with time,
It waits until the pseudo accelerator opening (ACPS) becomes 0%, and when it becomes 0%, the pseudo accelerator opening generating means 163 is cleared to end the generation of the pseudo accelerator.

The starting / normal injection control means 16 is provided with a second normal injection switching determination means 168 which makes a determination for switching the injection switching means 165 to the normal injection amount pattern storage means 161 side. The second normal injection switching determination means 1
Reference numeral 68 denotes the actual accelerator opening of the accelerator opening sensor 13 (AC
C) and the pseudo accelerator opening degree (ACPS) of the pseudo accelerator opening generation means 163 are input, and when it is determined that the accelerator pedal is depressed and the actual accelerator opening degree is larger than the pseudo accelerator opening degree, the injection switching means 165. Is switched from the starting injection amount pattern storage means 162 to the normal injection amount pattern storage means 161 side.

Next, a series of operations of this embodiment will be described. FIG. 6 is a flow chart for explaining the switching operation to the starting injection mode. In step 100 in this figure, it is determined whether or not it is the starting mode. The determination of the start mode may be made, for example, by turning on or off the starter switch. If the start mode is determined in step 100, step 101
Go to

In step 101, the actual accelerator opening (A
CC) is 0%. If the above conditions are satisfied, the routine proceeds to step 102, where the starting injection amount pattern storage means 162 enters the mode for searching the starting injection characteristic shown in FIG. On the other hand, if it is determined in steps 100 and 101 that the condition is not satisfied, in step 103, the normal injection amount pattern storage means 161 enters the mode for searching the normal injection characteristic shown in FIG.

FIG. 7 is a flow chart for explaining the operation of starting injection. In step 10 of this figure, the pseudo accelerator opening degree generation means 163 calculates the pseudo accelerator opening degree from the state of the engine water temperature as shown in FIG. In step 11, the starting injection amount is calculated from the starting injection pattern shown in FIG. 4 according to the pseudo accelerator opening degree ACPS.

In step 12, the first normal injection switching determination means 167 determines whether or not the actual engine speed (Ne) has become equal to or higher than Ne1 stored in advance. Ne
If it becomes 1 or more, it is assumed that the engine 1 has reached the complete explosion, and the procedure goes to step 13. In step 13, assuming that the complete explosion has been reached, the injection switching unit 165 switches the starting injection amount pattern storage unit 162 to the normal injection amount pattern storage unit 161, and switches from the starting injection pattern to the normal injection pattern. In this case, since the injection amount characteristic is determined by the larger one of the actual accelerator opening and the pseudo accelerator opening, the influence of discontinuity immediately after switching is reduced.

In step 14, the pseudo accelerator opening is attenuated with time, and in step 15, the pseudo accelerator opening is reduced to 0.
%, And in step 16, when the pseudo accelerator opening becomes 0%, the pseudo accelerator opening generation means 163.
To clear the generation of the pseudo accelerator opening. In this way, the effect of discontinuity immediately after switching is further reduced in consideration of the time decay of the pseudo accelerator opening.

In the process of steps 10 to 15, when the accelerator pedal is depressed and the actual accelerator opening takes a value larger than the pseudo accelerator opening, the second normal injection switching determination means 168 makes the normal injection. It is controlled according to the pattern. According to the control method described above, it is possible to freely set the injection amount pattern that suppresses the amount of white smoke emitted during the period from cranking to complete explosion such as low temperature starting and shortens the starting time. Since it can be framed separately from the injection amount characteristic that satisfies the drivability performance under normal conditions,
It is possible to achieve both improvement of startability and improvement of drivability performance.

In the present invention, whether or not the starting injection amount mode is entered is determined depending on whether the actual accelerator opening is 0%, but it may be determined by turning the idle switch on or off.

[0024]

As described above, according to the present invention, the amount of white smoke can be suppressed by the starting injection amount pattern which is determined by using the pseudo accelerator opening determined by the water temperature of the engine as a parameter, and the normal time Since it is possible to separate it from the injection amount characteristic that satisfies the drivability performance in the above, it is possible to achieve both improved startability and improved drivability performance.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an electronically controlled injection system for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a start / normal injection switching control means of FIG.

FIG. 3 is a diagram showing a normal injection amount characteristic stored in a normal injection amount pattern storage unit of FIG.

FIG. 4 is a diagram showing a starting injection amount characteristic stored in a starting injection amount pattern storage unit of FIG.

5 is a diagram showing a relationship between engine water temperature and pseudo accelerator opening degree in the pseudo accelerator opening degree generating means of FIG.

FIG. 6 is a flowchart illustrating a switching operation to a starting injection mode.

FIG. 7 is a flowchart illustrating the operation of starting injection.

[Explanation of Codes] 1 ... Engine 3 ... Injection Control Solenoid Valve 11 ... ECU 12 ... Engine Speed Sensor 13 ... Accelerator Opening Sensor 15 ... Various Sensors 16 ... Start / Normal Injection Control Means

Claims (1)

[Claims] 1. An electronically controlled injection system for an internal combustion engine, which electronically controls a fuel injection amount to an engine through an injection control electromagnetic valve, wherein a pseudo accelerator opening degree obtained from a water temperature of the engine is determined as a parameter. And a normal injection amount pattern determined by using a larger value of the pseudo accelerator opening amount and the actual accelerator opening amount, whichever is larger, and if the start mode is determined, the pseudo injection amount pattern When the control is started with the injection amount determined by the starting injection amount pattern based on the accelerator opening and the engine speed exceeds a predetermined value, the starting injection amount pattern is switched to the normal injection amount pattern, and the injection amount is changed. The electronically controlled injection system for an internal combustion engine is characterized in that the pseudo accelerator opening degree is attenuated with time.