JPH06235367A - Fuel injection control for engine - Google Patents

Abstract

PURPOSE:To permit the pressure relief for the pressure left in a fuel pipe by the simple operation after the stop of a fuel pump and improve workability by securing the safety when the necessity of demounting a fuel pipe is generated in the trouble diagnosis or the periodical inspection. CONSTITUTION:When a fuel pump is in stop, a specific instruction is inputted to judge if a fuel pressure relief demand exists or not (S201, S202), and if the fuel pressure relief demand exists, an injector is opened (S203). It is judged if a set time TST lapses or not from the opening of the injector (S204), and if the set time TST lapses, the injector is closed (S205). Accordingly, even in the case where the necessity of replacing a fuel filter in periodical time or demounting a fuel pipe in order to check the fuel pressure in the inspection of the trouble of a fuel injection system is generated, the pressure in the fuel pipe can be lowered to the pressure level free from the generation of the fuel blow-out by the simple operation, and safety is secured, and workability can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an engine capable of relieving pressure remaining in a fuel pipe after a fuel pump is stopped.

[0002]

2. Description of the Related Art Generally, in a fuel injection type engine in which fuel pumped by a fuel pump is injected from a fuel injection valve, an electronic control unit (EC
U) controls the engine. The ECU is provided with an external connection port capable of bidirectional communication with an external device such as a failure diagnosis device, and when the failure of the control system is to be confirmed, the operation data and the sensor inside the ECU are requested according to the request from the external device. It is designed to send data from other classes.

Further, the ECU can receive data from an external device and change the control data.
In the market, the applicant previously rewritten the adjustment data for changing the control target value of the idle speed in JP-A-2-191841 into new adjustment data received from the outside. A technique has been proposed in which the idling speed is set according to the load state of each engine, and in JP-A-2-191870, adjustment data for changing the ignition timing control parameter is received from the outside. By rewriting the new adjustment data described above, we propose a technology that sets the optimum ignition timing according to the state of each engine and operating conditions in the market.

[0004]

By the way, the fuel injection system of a fuel injection type engine is usually constructed so that the pressure leak in the fuel pipe is minimized even after the drive of the fuel pump is stopped due to the stop of the engine. Therefore, by maintaining a high fuel pressure, it is possible to prevent vaporization of fuel in the part that has become hot due to radiant heat from the engine, etc., and to prevent vapor from occurring, so that injection failure does not occur at the next restart. ing.

For this reason, regular replacement of the fuel filter,
Alternatively, if it becomes necessary to disconnect the fuel piping to check the fuel pressure during a fuel injection system failure inspection, the fuel will be blown out by the high fuel pressure remaining in the fuel piping, so be very careful to prevent danger. Must be carried out with caution, which was a factor that impairs workability.

The present invention has been made in view of the above circumstances, and after the fuel pump is stopped, the pressure remaining in the fuel pipe can be relieved by a simple operation, and the fuel pipe can be removed for failure diagnosis or periodic inspection. An object of the present invention is to provide a fuel injection control method for an engine, which can ensure safety and improve workability when a need arises.

[0007]

A first aspect of the present invention is a fuel injection control method for an engine, in which fuel is pumped by a fuel pump to control the opening / closing operation of a fuel injection valve to perform fuel injection. It is characterized by including a process of monitoring whether or not a specific command is input, and when the specific command is input, opening the fuel injection valve for a set time. A second invention is characterized in that the specific command in the first invention is inputted from an external vehicle diagnostic device.

[0008]

According to the first aspect of the present invention, when a specific command is input when the fuel pump is stopped, the fuel injection valve is opened for a set time to relieve the pressure in the fuel pipe. In the second aspect of the invention, when a specific command is input from the external vehicle diagnostic device when the fuel pump is stopped, the fuel injection valve is opened for a set time and the pressure in the fuel pipe is relieved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a flow chart showing a fuel pressure relief routine, FIG. 2 is a flow chart showing a fuel pump control routine, FIG. 3 is a flow chart showing a serial monitor routine, and FIG. 4 is a flow chart showing an engine control system. FIG. 5 is a schematic configuration diagram, FIG. 5 is a circuit configuration diagram of an engine electronic control system, FIG. 6 is a circuit configuration diagram of a serial monitor, and FIG. 7 is an explanatory diagram showing a connection between the ECU and the serial monitor.

In FIG. 4, reference numeral 1 is an engine,
In the figure, a horizontally opposed four cylinder engine is shown. An intake manifold 3 is communicated with each intake port 2a formed in the cylinder head 2 of the engine 1, a throttle chamber 5 is communicated with the intake manifold 3 through an air chamber 4, and an intake pipe is provided upstream of the throttle chamber 5. An air cleaner 7 is attached via 6.

Also, the air cleaner 7 of the intake pipe 6
An intake air amount sensor 8 composed of a thermal air flow meter such as a hot wire or a hot film is provided immediately downstream of the air conditioner, and a voltage depending on the throttle opening is applied to a throttle valve 5a provided in the throttle chamber 5. A throttle sensor 9 in which a throttle opening sensor 9a for outputting a value and an idle switch 9b having an idle contact which is turned on when the throttle valve is fully closed are incorporated is connected in series.

Further, an idle speed control valve (ISCV) 11 is provided in a bypass passage 10 that connects the upstream side and the downstream side of the throttle valve 5a, and the idle speed control valve (ISCV) 11 is directly connected to each intake port 2a of each cylinder of the intake manifold 3. A fuel injection valve (injector) 12 faces the upstream side.

Further, an ignition plug 13a whose tip is exposed to the combustion chamber is attached to each cylinder of the cylinder head 2 and is connected to the ignition plug 13a.
The igniter 14 is connected to b.

The injector 12 has a fuel supply path 15
The fuel tank 16 is communicated with the fuel tank 16 through the fuel tank 16. An in-tank type fuel pump 17 is provided in the fuel tank 16. The fuel from the fuel pump 17 is pressure-fed to the injector 12 and the pressure regulator 19 through the fuel filter 18 provided in the fuel supply passage 15, and is returned from the pressure regulator 19 to the fuel tank 16 to a predetermined position. Adjusted to pressure.

Further, a knock sensor 25 is attached to the cylinder block 1a of the engine 1, a water temperature sensor 27 is exposed to a cooling water passage 26 which communicates the left and right banks of the cylinder block 1a, and the cylinder head 2 of the cylinder head 2 is exposed. An O2 sensor 29 is exposed at the collecting portion of the exhaust manifold 28 communicating with the exhaust port 2b. Reference numeral 30 is a catalytic converter.

A crank rotor 31 is mounted on a crank shaft 1b supported by the cylinder block 1a, and a crank angle sensor 32 including a magnetic sensor such as an electromagnetic pickup or an optical sensor is provided on the outer periphery of the crank rotor 31. Are opposite to each other. Further, the cam rotor 33 is attached to the cam shaft 1c of the cylinder head 2.
The cam angle sensor 34 for discriminating the cylinder, which is composed of a magnetic sensor such as an electromagnetic pickup or an optical sensor, is provided on the outer periphery of the cam rotor 33 in a pair.

Protrusions (or slits) are formed on the outer circumference of the crank rotor 31 at predetermined crank angles, and each protrusion (or slit) is detected by the crank angle sensor 32. Further, a protrusion (or slit) for cylinder discrimination is formed on the outer periphery of the cam rotor 33, and the protrusion (or slit) is detected by the cam angle sensor 34.

In the electronic control unit 40, which will be described later, the engine speed, the ignition timing, etc. are set based on the detection signal from the crank angle sensor 32, and the combustion is performed based on the detection signal from the cam angle sensor 34. Determine the stroke cylinder.

On the other hand, in FIG. 5, reference numeral 40 denotes an electronic control unit (ECU) for processing signals from the respective sensors in the above-mentioned engine control system to drive actuators, and for performing fuel injection control, ignition timing control and the like. Is. This E
The CU 40 is mainly a microcomputer in which a CPU 41, a ROM 42, a RAM 43, a backup RAM 43a, a counter / timer group 44, an input interface (I / F) 45, and an output interface (O / F) 46 are connected to each other via a bus line 47. Configured as
Constant voltage circuit 4 for supplying a predetermined stabilizing voltage VC to each part
8. A drive circuit 49 for driving each actuator is incorporated.

The constant voltage circuit 48 is connected to a battery 51 via one relay contact of a power relay 50 consisting of a two-contact relay, and the power source is connected to the battery 51 via an ignition switch 52 and a diode 53. The relay coil of the relay 50 is connected. Also,
The battery 51 includes an ignition key switch 5
The fuel pump 17 is connected via the relay coil of the fuel pump relay 54 via 2a and the relay contact of the fuel pump relay 54.

Further, the I / F 45 includes an intake air amount sensor 8, a throttle opening sensor 9a, and a knock sensor 2.
5, water temperature sensor 27, O2 sensor 29, crank angle sensor 32, cam angle sensor 34, vehicle speed sensor 55, and other sensors are connected, and idle switch 9
b, air conditioner switch 56, inhibitor switch 57,
Switches such as a neutral switch 58, a power steering steering switch 59, and a starter switch 60 are connected.

Further, the igniter 1 is connected to the O / F 46.
4 is connected and via the drive circuit 49,
The ISCV 11, the injector 12, the engine check lamp 61 that is turned on to issue a warning when the system abnormality is detected by the self-diagnosis function, the fuel pump relay 5
4 is connected to the relay coil of the power supply relay 50 in order to realize a self-shut function of keeping the ECU power supply on for a predetermined time after the ignition switch 52 is turned off and the engine is stopped. It is connected to the connection point with the cathode side of the diode 53.

The ROM 42 stores a control program and fixed data for various controls, and the RAM 43 stores data obtained by processing output signals of the sensors and switches and the CPU 41. Stores data that has been arithmetically processed. Further, the backup RAM 43a is constantly supplied with power regardless of the operating state of the ECU 40 to stop the operation of the engine.
Even if the CU power is turned off, the stored contents are not lost, and a trouble code or the like corresponding to the faulty part detected by the self-diagnosis function is stored.

In the CPU 41, the idle speed control amount, the fuel injection amount, the ignition timing, etc. are set according to the control program stored in the ROM 42, and the corresponding signals are sent to the ISCV 11, the injector 12, and the igniter 1.
4 to perform various controls such as idle speed control, fuel injection control and ignition timing control.

Further, the ECU 40 is provided with an external connection connector 62. The external connection connector 62 is connected to the O / F 46 and the battery 51 is connected via a relay contact of the power relay 50. Serial monitor 7 connected to the outside as a vehicle diagnostic device
0 is connectable.

The serial monitor 70 is provided in a dealer service station or the like, and as shown in FIG. 7, the serial monitor 70 is connected to an external connection connector 62 of the ECU 40 mounted on the vehicle 100 via an adapter harness 63. By connecting the input / output connector 64 of the above, the input data from the various sensors input to the ECU 40 and the control data for the actuators are read into the serial monitor 70, and the data values thereof are displayed to perform the failure diagnosis. It is a thing.

As shown in FIG. 6, the serial monitor 7 is
0 is provided with a control unit 71 composed of a microcomputer, a power supply circuit 72, etc. inside the main body 70a, and the power supply circuit 72 is connected to the vehicle 100 via a power switch 73.
Connected to the battery 51 of each of the parts, and a predetermined stabilization voltage V is applied to each part.
It is designed to supply C.

Further, the serial monitor 70 is provided with an indicator portion 74 having a plurality of light emitting diodes (LEDs) D1 to D10, a display 75 such as a liquid crystal display, a keyboard 76, etc. on the outside.
A memory cartridge 78 is detachably connected to the control unit 71 from the outside via a connector 77.

The memory cartridge 78 can be selectively connected through the connector 77 so that the main body 70a of the serial monitor 70 itself is compatible with the programs of the ECU 40 which differ depending on the vehicle type. ROM for storing a diagnostic program and fixed data according to the program of the vehicle type.
79 is stored.

Then, by connecting the memory cartridge 78 to the main body 70a, the control section 71 is controlled by C
The PU 80, the RAM 81, the ROM 79 of the memory cartridge 78, the first and second input / output (I / O) interfaces 82, 83, etc. are connected to each other via the bus line 84, and the ROM 79 is operated in accordance with the operation input from the keyboard 76. It is designed to run the diagnostic programs in.

The above first I / O interface 82
The keyboard 76 and the E
The O / F 46 of the CU 40 is connected to the keyboard 76.
The operation input signal from the
Various control data in 40 and output data of various sensors are input, and the display 75 and the I / F 45 of the ECU 40 are connected to the output port of the first I / O interface 82. Various commands such as data value display and data transmission request to the ECU 40 are output.

Further, the O / F 46 is connected to the input port of the second I / O interface 83, and the binary data in the ECU 40 corresponding to the switch signal from the switches of the vehicle 100, and ECU 4 above
ON of control signal output from 0 to actuators,
Binary data indicating the OFF state is input, and the second data
The indicator section 74 is connected to the output port of the I / O interface 83 of the
By turning on and off, the LED of the indicator portion 74 corresponding to the switch is turned on and off, and the operation of each switch can be confirmed.

Next, of the control operations of the ECU 40,
The operation relating to the fuel pressure relief of the present application will be described with reference to the flowcharts of FIGS.

FIG. 2 shows a fuel pump control routine executed every predetermined time after the power supply to the ECU 40 is turned on.
In step S101, set time T1FP from turning on the ECU power
It is checked whether (for example, 5 seconds) has elapsed.

When the set time T1FP has not elapsed, the routine proceeds from step S101 to step S104, where the output port value of the O / F 46 for the fuel pump relay 54 is set to 1 (GFP ← 1), and the fuel pump relay is set. 5
Turn ON 4 and exit the routine. On the other hand, the above steps
When the set time T1FP has elapsed in S101, step S
After proceeding to 102 and the crank pulse is input from the crank angle sensor 32, the set time T2FP (for example, 0.5s
Check whether ec) has elapsed.

When the set time T2FP has not elapsed from the crank pulse input in the above step S102, the output port value GFP is set to 1 and the routine is exited in step S104, and the set time T2FP elapses from the crank pulse input. From step S102 to step S103, the output port value GFP of the O / F 46 for the fuel pump relay 54 is set to 0 (GFP ← 0), and the fuel pump relay 5
Turn OFF 4 and exit the routine.

That is, immediately after the ECU power is turned on, the fuel pump relay 54 is turned on to drive the fuel pump 17, and when the time T1FP elapses, when the crank pulse input interval becomes longer than the time T2FP (corresponding to about 30 rpm). ) It is judged that the engine is stopped and the fuel pump relay 54 is turned on.
The fuel pump 17 is stopped by setting it to FF.

Here, the serial monitor 70 equipped with the memory cartridge 78 corresponding to the vehicle 100 is connected directly via the input / output connector 64 and the external connection connector 62 or via the adapter harness 63, and the power switch is connected. When 73 is turned on, the routine shown in FIG. 3 is started.

In the routine of this serial monitor 70,
First, in step S301, the system is initialized, and then in step S302, the ROM 4 of the ECU 40 is read.
In order to read the model code (vehicle type, year model) stored in 2, the model code request is output to the ECU 40.

Then, in step S303, it is determined whether or not the ECU 40 responds to receive the model code transmitted from the ECU 40. If the model code can be received, the process proceeds to step S304. If not, the process proceeds to step S303. It returns and repeats the reception determination.

In step S304, the model is read from the received model code and stored in a predetermined address of the RAM 81 of the main body 70a. Then, in step S305, from among a plurality of tables stored in the ROM 79 of the memory cartridge 78. , Select the table corresponding to the model code above. Then, first, the head of the table corresponding to the model is designated, and, for example, the year display program is selectively executed, and the year data corresponding to the year of the vehicle is read from the model code stored in the predetermined address of the RAM 81. The year number is displayed on the display 75.

Next, the above steps S305 to S306
Then, it is determined whether or not a key input is made from the keyboard 76, and if there is a key input, the process proceeds to step S307, and if there is no key input, the key input is awaited. When a key input is made and the process proceeds to step S307, the content of the key input is, for example, F →
It is determined that C → ENT and that the fuel pressure relief command mode is set.

When in the fuel pressure relief command mode, the routine proceeds from step S307 to step S308, where a fuel pressure relief command is transmitted to the ECU 40 so as to execute the process for releasing the pressure in the fuel pipe of the vehicle 100, and step S309 Then, a mode indication is displayed on the display 75 that the fuel pressure relief command is currently issued.

As a result, a fuel pressure relief routine on the side of the ECU 40, which will be described later, releases the pressure in the fuel pipe and sends a fuel pressure relief end notification from the ECU 40. When this fuel pressure relief end notification is received in step S310, In step S311, the end of the fuel pressure relief is displayed on the display 75, and the process returns to step S306 described above to wait for the next key input.

On the other hand, if it is determined in step S307 that the fuel pressure relief command mode is not set, the process branches from step S307 to step S312 to determine whether another mode input has been made. Judgment is made and an error message is displayed in step S317
Returning to the wait for key input in S306, when the mode is input, the process proceeds to step S313, the diagnostic program corresponding to the mode is selected, and the abbreviation and unit in the corresponding mode are read from the fixed data table of the ROM 79 and RA
The data is stored in a predetermined address of M81 and the ECU 40 is requested to transmit data corresponding to the mode.

Then, in step S314, when the data from the ECU 40 is received, in step S315 the received data is calculated and converted into a physical quantity to convert it from a binary number to a decimal number, and in step S316, the converted data is displayed on the display 75.
And waits for the next key input in step S306 described above.
For example, when the content of the key input is F → 0 → 1 → ENT, the battery voltage display program is selected from the table corresponding to the model code of the ROM 79, and the abbreviated name (corresponding to the diagnostic mode F01 from the fixed data table). VB) and unit (V) are read, and the above steps are performed.
S313 to S316 are executed and displayed on the display 75 as shown in FIG.

Through the above procedure, the serial monitor 70
When a specific fuel pressure relief command is transmitted from the ECU 40 to the ECU 40, when the fuel pump 17 is stopped, the ECU 40 performs a process for releasing the pressure in the fuel pipe by the fuel pressure relief routine shown in FIG. It is possible to safely remove the fuel pipe for replacement of the fuel filter 18 or for checking the fuel pressure at the time of failure inspection of the fuel injection system.

The fuel pressure relief routine will be described below. This routine is a routine executed every predetermined time, and in step S201, it is checked whether or not the fuel pump 17 is stopped by referring to the output port value GFP of the O / F 46 for the fuel pump relay 54. , GFP
When the fuel pump 17 is driven at = 1, the routine is exited as it is, and when the fuel pump 17 is stopped at GFP = 0, the process proceeds to step S202.

In step S202, it is checked whether or not a specific command has been input and there is a fuel pressure relief request. If there is no fuel pressure relief request, the routine is exited and the fuel pressure relief command from the serial monitor 70 is received. If it is determined that there is a fuel pressure relief request, step S2
In step 03, a fully open drive signal with a duty ratio of 100% is output to the injector 12 of each cylinder to open the injector 12 of each cylinder.

Then, in step S204, the injector 1
It is checked whether the set time TSET has elapsed since the valve 2 was opened. This set time TSET is the time required to release the high-pressure fuel pressure in the fuel pipe by opening the injector 12 and reduce the pressure level to a pressure level where there is no danger of fuel blowout even if the fuel pipe is removed. Values corresponding to the engine type, such as the displacement (injector capacity) and the number of cylinders (the number of injectors), are stored in the ROM 42 in advance.

When the set time TSET has not elapsed since the injector 12 was opened in step S204, the drive signal of the injector 12 in step S203 is held, and when the set time TSET has elapsed, the process proceeds to step S205. Then, the drive signal for the injector 12 is turned off to close the valve, and in step S206, when the fuel pressure relief request is cleared, the process proceeds to step S207, the fuel pressure relief end notification is transmitted to the serial monitor 70, and the routine is executed. Get out.

Thus, even if it becomes necessary to remove the fuel pipe for periodical replacement of the fuel filter 18 or checking of the fuel pressure at the time of trouble inspection of the fuel injection system, a simple operation is required. It is possible to release the pressure in the fuel pipe, ensure safety and improve workability.

As described in this embodiment, the ECU 4
It is desirable to connect the serial monitor 70 to the outside of 0 to send the fuel pressure relief command, because it is possible to ensure the safety of the work and diagnose the failure at the same time, but the present invention is not limited to the embodiment. , For example, the ECU 40
When a specific connector or switch is installed so that it cannot be easily touched by the user and this specific connector or switch is turned on at a dealer service station, etc., a signal as a specific command for instructing fuel pressure relief is generated. It may be input.

[0054]

As described above, according to the present invention, it is monitored whether or not a specific command is input when the fuel pump is stopped, and when the specific command is input, the fuel injection valve is set for a set time. Since it includes a process to open the valve only, it is possible to relieve the pressure remaining in the fuel pipe with a simple operation, and ensure safety when it is necessary to disconnect the fuel pipe for failure diagnosis or periodic inspection. It is possible to obtain excellent effects such as improving the property.

[Brief description of drawings]

FIG. 1 is a flowchart showing a fuel pressure relief routine.

FIG. 2 is a flowchart showing a fuel pump control routine.

FIG. 3 is a flowchart showing a serial monitor routine.

FIG. 4 is a schematic configuration diagram of an engine control system.

FIG. 5 is a circuit configuration diagram of an engine electronic control system.

FIG. 6 is a circuit configuration diagram of a serial monitor.

FIG. 7 is an explanatory diagram showing a connection between an ECU and a serial monitor.

[Explanation of symbols]

 1 engine 12 injector (fuel injection valve) 17 fuel pump 40 ECU 70 serial monitor (vehicle diagnostic device) TSET set time

Claims (2)

[Claims] 1. A fuel injection control method for an engine in which fuel is pumped by a fuel pump to control the opening / closing operation of a fuel injection valve to inject fuel, and it is determined whether a specific command is input when the fuel pump is stopped. A method for controlling fuel injection of an engine, comprising: monitoring and opening the fuel injection valve for a set time when the specific command is input. 2. The fuel injection control method for an engine according to claim 1, wherein the specific command is input from an external vehicle diagnostic device.