JP2002317672A - Fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection system having a function to reduce the common rail pressure for suppressing vibrations and noise emission at restarting of an engine immediately after the engine is stopped, in which the load of the battery is reduced. SOLUTION: The fuel injection system A includes an engine control means 7 which impresses drive pulses on injection controlling solenoid valves 1 for a specified period of time if an IG switch being on is turned off and an instruction for engine stop is given, the drive pulses having such a short period as not allowing the fuel to be injected into the cylinders from injectors 3, and reduces the common rail pressure until the at-starting target value is attained as set lower than the idling target value, and when the specified period has elapsed, gives an instruction of stopping the supply of the working power to the engine controlling means itself 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common rail type fuel injection system.

[0002]

2. Description of the Related Art A plurality of injectors for injecting fuel into each cylinder of an engine from a common rail into which compressed fuel is press-fitted by opening an injection control solenoid valve, a plurality of sensors for detecting an operating state of the engine, 2. Description of the Related Art A common rail type fuel injection system including an engine control device that drives an injection control electromagnetic valve based on each sensor signal output by the above sensor has been conventionally known.

[0003] In this fuel injection system, in the engine stop transition state when the ignition is switched from ON to OFF, the pump control valve is fully opened, and the fuel supply to the common rail is at a maximum. In addition, since the injector is energized and cut off at the same time as the ignition is turned off, the injector is in a non-injection state, and the fuel pressure in the common rail is equal to or higher than the target value during idling. As a result, when starting the engine shortly after the engine is stopped (including restarting when the start of the cold start fails), the starting pressure is higher than the target value for the start. Generates vibration and noise.

Japanese Unexamined Patent Publication No. 11-173189 discloses a technique for preventing the above-described problem by performing idle driving to reduce the common rail pressure upon detecting that the ignition has been turned from ON to OFF.

[0005]

However, when the common rail pressure does not decrease or the decreasing speed is slow due to the following reasons, the idling continues for a long time and a large load is applied to the battery.・ If the engine keeps running,
When the engine speed drops slowly.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the load on a battery in a fuel injection system having a function of reducing a common rail pressure in order to suppress the generation of vibration and noise when the engine is restarted immediately after the engine is stopped. It is in.

[0007]

A pressure sensor detects a common rail pressure. The plurality of sensors are provided to detect an operating state of the engine, and output sensor signals such as an accelerator opening, an engine speed, and a pump signal.

[0008] The supply pump has a discharge amount control means for compressing the fuel and adjusting the discharge amount of the compressed fuel to the common rail. The engine control device controls the injection control solenoid valve and the discharge amount control means based on each sensor signal output by the pressure sensor and the plurality of sensors, and maintains the common rail pressure at a predetermined target pressure. The plurality of injectors inject fuel from the common rail to each cylinder of the engine by opening an injection control electromagnetic valve.

When the user gives an instruction to stop the engine by turning the ignition switch from on to off, the engine control device reduces the common rail pressure for a predetermined time until the starting target value set lower than the idling target value is reached.

In reducing the common rail pressure until the starting target value set lower than the idle target value is reached,
Specifically, the engine control device applies a short-period drive pulse to the injection control solenoid valve such that fuel is not injected into the cylinder from each injector, or sets a command value at which the common rail pressure becomes a target value at the time of starting. At least one of the instructions to the discharge amount control means is performed. Then, after the predetermined time has passed, regardless of the degree of decrease in the common rail pressure,
Instructs to stop supplying the operating power to the engine control device itself.

Thus, the common rail pressure immediately after the engine is stopped can be reduced to the target value at the time of starting, and when the ignition switch is turned off from on and the engine is restarted shortly after the engine stops. Generation of vibration and noise can be reduced.

Further, after the predetermined time has elapsed, the supply of the operating power to the engine control device is stopped, so that the power supply to the injection control solenoid valve and the discharge amount control means is also stopped. Thereby, the load on the battery can be reduced.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention (Claim 1,
2) will be described with reference to FIG. 1, FIG. 2, and FIG.

As shown in FIG. 5, the fuel injection system A includes:
By opening the injection control solenoid valves 1, 1,.
Injectors 3, 3, ... 3 for injecting fuel into each cylinder of
A high-pressure supply pump 4 having a throttle valve 41 and a pressure sensor 5
And a fuel tank 6 and an engine control means 7.

The injectors 3, 3,... 3 are arranged corresponding to the combustion chambers of each cylinder of the engine 2. Fuel injection from these injectors 3 into each combustion chamber is controlled by opening and closing the injection control solenoid valve 1.

Each injector 3 is connected to a common rail 8 (high-pressure accumulating pipe), and while the injection control solenoid valve 1 is open, high-pressure fuel in the common rail 8 is injected into each combustion chamber.

The high-pressure supply pump 4 pressurizes the fuel 61 sucked from the fuel tank 6. This high pressure supply pump 4
The supply capacity is controlled by a throttle valve 41 (discharge amount control means) controlled by the engine control means 7. Then, the fuel 61 which has been pressurized by the high-pressure supply pump 4 is supplied to the common rail 8 via a check valve and a supply pipe 42, and the inside of the common rail 8 is constantly maintained at a high pressure at which fuel injection is possible. The maximum operating pressure is 120 MPa.
１６０160 MPa.

The pressure sensor 5 is disposed at one end of the common rail 8 for detecting the pressure in the common rail 8,
The sensor output corresponding to the common rail pressure is sent to the engine control means 7. Then, the common rail pressure is detected by the engine control means 7.

The engine control means 7 controls the injection control solenoid valves 1, 1... 1 and the throttle valve 41 of the high-pressure supply pump 4 based on the operating state of the engine and the common rail pressure detected by the pressure sensor 5. I do.

The operating conditions of the engine include sensor outputs 71, 72, 73, such as an accelerator opening signal, a rotation speed sensor (not shown) for detecting engine rotation, and a pump signal.
It is grasped by. Then, the engine control means 7 controls the injection control solenoid valves 1 and 2 so that the injection timing and injection amount (= injection period) are optimal for the determined operating state of the engine.
A drive signal is output to 1 ... 1.

The engine control means 7 throttles an output value based on the calculated opening command value while monitoring the common rail pressure so that the injection pressure becomes an optimum value in accordance with the detected vehicle load and engine speed. Output to the valve 41.

Next, the operation of the engine control means 7 of the fuel injection system A of this embodiment will be described with reference to the flow chart of FIG.
A description will be given based on the waveform diagram of FIG.

In step s10, the IG switch is turned ON.
It is determined whether or not it is within a predetermined time (for example, 10 seconds) after turning off, and if it is within the predetermined time (YES)
Proceeds to step s20, and if the predetermined time has passed (NO), proceeds to step s80.

In step s20, the starting target pressure Pst
Is calculated, and the process proceeds to step s30. Note that the starting target pressure Pst is calculated based on a sensor signal such as a water temperature. In step s30, the actual pressure Pr of the common rail 8 output from the pressure sensor 5 is captured, and the process proceeds to step s40.

In step s40, it is determined whether or not the actual pressure Pr of the common rail 8> the target pressure Pst at the time of starting is established. If it is established (YES), the process proceeds to step s50. If it is not established (NO), the process proceeds to step s50. Proceed to s60.

At step s50, a short drive pulse Tm at which fuel is not injected from the injector 3 is set as a command value for the injection control solenoid valves 1, 1,..., And the routine proceeds to step s70.

In step s60, in order to stop the operation of the injector 3, the drive pulse Tm is set to 0, and the process proceeds to step s70. In step s70, the short drive pulse Tm
Alternatively, Tm = 0 is set in the output stage as the injector drive command value. In step s80, the engine control means 7
Set the command value to turn off the power supply for operation.

The fuel injection system A of this embodiment has the following advantages. In the fuel injection system A, the engine is stopped by turning the IG switch from ON to OFF and shortly after the engine is stopped, the engine can be started again (including restarting when the start of the cold start fails). Easy to use because vibration and noise are small.

Further, when a predetermined time (for example, 10 seconds) has passed since the IG switch was turned ON → OFF (N
In O), a command value for turning off the operating power supply to the engine control means 7 is set, so that the injection control solenoid valves 1, 1... 1 and the throttle valve 41 of the high-pressure supply pump 4 are energized. Also stop. Thereby, the electric load on the battery can be reduced, and the deterioration of the battery can be prevented.

Next, a second embodiment of the present invention will be described.
2) will be described with reference to FIGS. The operation of the engine control means 7 of the fuel injection system B of the present embodiment
This will be described based on the flowchart of FIG. 3 and the waveform diagram of FIG. Note that steps s51, s61, and s71 are different from the fuel injection system A.

At step s40, it is determined whether or not the actual pressure Pr of the common rail 8> the target pressure Pst at the time of starting is established. If it is established (YES), the process proceeds to step s51. If it is not established (NO), the process proceeds to step s51. Proceed to s61.

At step s51, the throttle valve 41 is determined from the difference between the actual pressure Pr of the common rail 8 and the starting target pressure Pst.
Is calculated, and the process proceeds to step s71.
Opening command value Di = f (Pr-Pst) for throttle valve 41

In step s61, an opening command value Di for fully closing the throttle valve 41 is calculated. In step s71,
The opening command value Di to the throttle valve 41 is set in the output stage.

The fuel injection system B of this embodiment has the following advantages. In the fuel injection system B, the IG switch is turned ON → OFF to stop the engine, and when the engine is stopped shortly after, the engine is started again (including restart when the start of the cold start fails). Easy to use because vibration and noise are small.

Further, when a predetermined time (for example, 10 seconds) has passed since the IG switch was turned ON → OFF (N
In O), a command value for turning off the operating power supply to the engine control means 7 is set, so that the injection control solenoid valves 1, 1... 1 and the throttle valve 41 of the high-pressure supply pump 4 are energized. Also stop. Thereby, the electric load on the battery can be reduced, and the deterioration of the battery can be prevented.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation of a fuel injection system according to a first embodiment.

FIG. 2 is a waveform chart showing timing of each signal according to the first embodiment.

FIG. 3 is a flowchart showing an operation of the fuel injection system according to the second embodiment.

FIG. 4 is a waveform chart showing timing of each signal according to the second embodiment.

FIG. 5 is a block diagram of a fuel injection system according to first and second embodiments of the present invention.

[Explanation of symbols]

 A, B Fuel injection system 1 Injection control solenoid valve 2 Engine 3 Injector 5 Pressure sensor 7 Engine control means 8 Common rail 41 Throttle valve (discharge amount control means)

Continued on the front page F term (reference) 3G060 BA19 BC03 BC09 CA01 CB09 DA09 DA12 FA07 GA14 GA19 3G066 AA01 AA07 AB02 AC09 AD02 BA06 BA22 BA46 CA01Z CC53 CD03 CE21 CE29 DB01 DB07 DB12 DB19 3G301 HA01 HA02 HA04 JA37 KA28 LB04 LB08 LC01 MA NB20 NE06 NE17 NE18 PB08Z PE09Z PF16Z

Claims (2)

[Claims] 1. A plurality of injectors for injecting fuel from a common rail to each cylinder of an engine by opening an injection control solenoid valve, and a fuel for compressing fuel and adjusting a discharge amount of compressed fuel to the common rail. A supply pump having an amount control means, a pressure sensor for detecting a common rail pressure, a plurality of sensors provided for detecting an operating state of the engine, and the sensor signals output by the pressure sensor and the plurality of sensors A fuel control system that controls the injection control solenoid valve and the discharge rate control means based on the engine control device to maintain the common rail pressure at a predetermined target pressure.The engine control device includes an ignition switch. When the engine is stopped from on to off, the idle A fuel injection system that reduces the common rail pressure until a start target value set lower than a target value is reached, and instructs, after the predetermined time, a supply of operating power to the engine control device to stop. . 2. In reducing the common rail pressure until a start target value set lower than the idle target value is reached, the engine control device operates the drive in a short cycle such that fuel is not injected from each injector into a cylinder. At least one of applying a pulse to the injection control solenoid valve or instructing the discharge amount control means of a command value at which the common rail pressure becomes the target value at the time of starting is performed. 2. The fuel injection system according to claim 1.