JPH0610724A - Battery-less electronic fuel injection control device for engine - Google Patents

Abstract

PURPOSE:To facilitate the re-start-up of an engine at the time of warming up by effectively utilizing the small number of ignition timing at the time of start-up of a manual start-up engine. CONSTITUTION:A fuel injection valve starting unit 38 outputs the starting signal s2 on the basis of the rise of ECU detecting signal supplied from a completion of reset operation detecting unit 37 to open an injection valve 10. The first fuel injection is performed independently from the existence of TDC pulse. The first fuel injection is performed during the time set by a timer 35, and thereafter, the fuel is injected for a valve open time read from a map memory 36 on the basis of the detecting signal s4 of the TDC pulse. At the time of engine stop operation, the fuel is injected for a predetermined time by an engine stop control unit 42 after the turn-off of an ignition switch till the output of a motor becomes the operating voltage of the ECU or less.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic fuel injection control device for an engine, and more particularly to a batteryless electronic fuel injection control device for a small displacement engine without a battery.

[0002]

2. Description of the Related Art An electronic fuel in which a fuel injection valve is arranged in an intake system of an engine and the opening time of the fuel injection valve is controlled according to the operating state of the engine to adjust the fuel injection amount. Injectors are known.

In recent years, the application of the electronic fuel injection device has begun to be applied to a small displacement engine such as a general-purpose engine or an agricultural engine that is manually started by a rope starter, that is, a recoil starter system without mounting a power battery.

In an electronic fuel injection system that does not use a battery, during operation, an electronic control unit (hereinafter referred to as an ECU) including a microcomputer from a generator attached to an engine.
That is, sufficient power is supplied, and stable operation is performed. However, at the time of starting by the recoil starter, sufficient electric power is not supplied to the ECU, so that the fuel injection valve cannot be operated.

The relationship between various parameters at the time of starting and the timing of control signals will be described with reference to FIG. Immediately after the cranking by the recoil starter start operation is started, the engine speed Ne rapidly increases, the generator output voltage VACG induced by the rotation of the flywheel of the engine also rapidly increases, and the inertia of the flywheel is increased. When the rotation speed exceeds a predetermined value, a substantially stable voltage range is reached. After that, when the start is successful, the engine speed Ne is further increased as shown by the solid line a and the engine is driven by itself, and the generator output voltage VACG is maintained at a substantially constant value. If the start fails, the engine speed N as shown by the dotted line b
e and the generator output voltage VACG decrease.

When the TDC pulse P1 indicating the top dead center is detected at the timing t6, the ECU outputs a fuel injection valve starting signal. When the fuel injection valve activation signal is supplied,
In response to this, a predetermined terminal voltage is applied to the fuel injection valve, a current flows through the valve drive coil to open the valve, and fuel is injected into the intake manifold. As a result, the fuel is ignited at the ignition timing immediately after the fuel injection, and the engine starts self-driving.

By the way, as shown in the figure, the ECU enters the reset operation at the timing t1 when the generator output voltage reaches the minimum operating voltage V _E of the ECU, but since the reset is completed and rises, it takes up to the timing t4. , This E
In the CU, the TDC pulse P1 is not detected at the timing t3 before that. On the other hand, at the subsequent timing t6, the reset operation is completed and the ECU has started up, so the TDC pulse P1 is detected, and in response thereto, the fuel injection valve activation signal is turned on.

As described above, since fuel cannot be injected with the TDC pulse P1 before the ignition timing at the timing t5, the ignition chance in one starting operation by the recoil starter is the timing under the generator output voltage shown in FIG. There will be only one at t6. Therefore, there is a problem that the possibility of successful starting is reduced and the number of repeated starting operations is increased due to unsuccessful starting. The fuel injection valve reaches the minimum operating voltage V _J at timing t2.

On the other hand, in Japanese Patent Laid-Open No. 63-170528, a starting fuel supply device used only at the time of starting, and an engine starting operation detection operated by negative pressure in the intake passage when the engine is manually started. A fuel injection device provided with means has been proposed. This fuel injector has
When the engine start operation detecting means detects the start of the engine, the fuel is supplied to the starting fuel supplier and the fuel is ejected to the intake passage.

That is, in the fuel injection device, the starting fuel injector is not opened by using the actuator operated by electric power, but is provided upstream of the starting fuel injector by the mechanical force generated by the negative pressure in the intake passage. The valve is opened to supply fuel from the fuel tank to the starting fuel injector.
The fuel tank is installed at a position higher than the starting fuel injector, and fuel is supplied by head pressure.

Further, in the fuel injection device disclosed in Japanese Patent Laid-Open No. 63-259129, the control of the microcomputer is not performed until the engine starts to operate by itself.
The electric power is supplied to the fuel injection valve through another path to open the fuel injection valve and inject the starting fuel.

[0012]

The above fuel injection device has the following problems. First, in the fuel injection device described in the former publication, it is necessary to provide a starting fuel injector, a communicating pipe for negative pressure detection, and a negative pressure operating valve for fuel injection only at the time of starting. The increase of such accessory components in the small displacement engine to which the recoil starter system is applied not only complicates the fuel supply system, but also
This is not preferable because it leads to an increase in the size of the engine.

Further, there is a problem that the fuel supply pressure is not stable in the fuel supply by the head pressure. In order to maintain a sufficient fuel supply pressure (fuel pressure) in a stable manner, it is desirable to install a pump that can forcibly pressurize and supply fuel, but when starting the engine in the recoil starter system, a sufficient fuel pressure can be obtained immediately by the pump. It is difficult to secure a sufficient amount of fuel at the time of starting, and therefore, there remains a problem that a sufficient amount of fuel cannot be injected at the time of starting.

On the other hand, in the fuel injection device described in the latter publication, fuel is injected without control of the microcomputer until the engine start is completed after the voltage of the fuel injection valve reaches its minimum operating voltage. Therefore, the fuel supply amount becomes too large, and a large amount of unburned exhaust gas tends to be discharged at the time of starting. Further, when cranking is repeated by restarting operation due to a start failure, a large amount of unburned gas is retained in the cylinder, which causes a problem that ignition difficulty gradually increases.

Further, it may be difficult to start the engine not only when it is cold but also when it is warmed up. In a recoil starter type electronically controlled fuel injection device that does not have a power supply battery, even when restarting during warm-up, the start of the power supply is delayed and the start of fuel injection tends to be delayed, or the fuel pressure is low. It may be difficult to secure a sufficient fuel injection amount.

Therefore, in comparison with the conventional engine that employs the carburetor system that can be easily restarted by operating the recoil starter, the electronically controlled fuel injection device tends to be significantly inferior in restart performance during warm-up. There is.

However, the engine is often restarted after being stopped for only a short time. For example, in the case of an engine for a tiller, when the grass is entangled in the work rotary and it is necessary to remove it or when it becomes necessary to refuel, the engine is temporarily stopped and the It may restart after performing maintenance work. In such a case, the operator expects that the engine will be warm so that it can be easily started, but there was a tendency that this expectation could not be sufficiently satisfied for the above-mentioned reason.

The object of the present invention is to solve the above problems.
To provide a batteryless electronic fuel injection control device for an engine capable of ensuring an appropriate amount of fuel injection at the time of starting and restarting without complicating or increasing the configuration of a small displacement engine without a battery. It is in.

[0019]

SUMMARY OF THE INVENTION To solve the above problems and to achieve the object, the present invention relates to a recoil starter, a fuel injection valve for supplying fuel to an intake passage of an engine, and an operating state of the engine. A microcomputer for controlling the opening time of the fuel injection valve, an ignition device, and electric power generated by rotation of a flywheel connected to the crankshaft of the engine are supplied to operate the fuel injection valve and the microcomputer. The ignition device includes power supply means and fuel supply means for supplying fuel pressurized by a mechanical pump driven in association with rotation of the flywheel to a fuel injection valve, corresponding to an engine stop operation. Stop the ignition operation, and after this ignition operation is stopped, fuel injection is performed for a predetermined period based on the control output from the microcomputer. It is characterized in that configured to perform.

[0020]

According to the present invention having the above characteristics, an appropriate amount of fuel is injected into the intake system after the ignition operation is stopped. Therefore, when restarting, the recoil starter can be promptly started with a few ignition timings within the cranking time by the starting operation.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing a configuration of an engine according to an embodiment of the present invention. In the figure, a piston 2 and a spark plug 4 are arranged in a cylinder 2 of an engine 1. An intake valve 5 is provided in an intake port 6 opening to the upper part of the cylinder 2, and the intake port 6 communicates with the atmosphere via an intake pipe 7 and an air cleaner 8. A throttle valve 9 is provided in the middle of the intake pipe 7, and a fuel injection valve (hereinafter, simply referred to as an injection valve) 10 and an intake air temperature sensor 11 that detects an intake air temperature are arranged upstream of the throttle valve 9. Fuel is injected by the injection valve 10 on the upstream side of the throttle valve 9 of the intake pipe 7.

A flywheel 13 is fixed to a crankshaft 12 of the engine 1, and six first magnets 14 and one second magnet 15 are attached to the inner circumference and the outer circumference of the flywheel 13, respectively. ing.
Six convex portions 16 a provided on the stator core 16 and a convex portion 16 a are provided at a position facing the first magnet 14.
A power generation winding portion including a winding wire 17 wound around is disposed.

The first magnet 14 and the power generation winding portion constitute a power source portion for driving the injection valve. The winding wire 17 is connected to a power supply circuit 34 that rectifies and stabilizes a generated voltage, and the power supply circuit 34 is an electronic control unit (hereinafter, referred to as
The power supply voltage is supplied to the ECU 30).

On the other hand, an ignition device unit 18 including an ignition coil is provided at a position facing the second magnet 15. The ignition device unit 18 is connected to the spark plug 4 via a lead wire 33. The ignition device unit 18 in this embodiment is composed of a self-trigger ignition device.

A fuel pump 22 for pressurizing the fuel supplied to the injection valve 10 and a cam 20 for driving the fuel pump 22 are arranged above the cylinder 2. A pulley 20a is fixed to a shaft 21 of the cam 20, a timing belt (not shown) is installed between the pulley 20a and the crankshaft 12, and the cam 20 is driven by the rotation of the crankshaft. A third magnet 20b is provided on the outer peripheral surface of the pulley 20a, and a TDC sensor 19 for detecting the TDC timing is provided at a position facing the third magnet 20b.

The inlet side of the fuel pump 22 is connected to the fuel tank 24 via a pipe 23, and the outlet side of the fuel pump 22 is connected to the injection valve 10 and the pressure regulator 27 via a pipe 26. A fuel filter 25 is provided at the tip portion of the pipe line 23 opening to the fuel tank 24, and the fuel in the fuel tank 24 is supplied to the fuel pump 22 via the fuel filter 25 and the pipe line 23.

The fuel pressurized by the fuel pump 22 is supplied to the conduit 2
6 to the injection valve 10. The pressure regulator 27 has a negative pressure chamber 27b and a fuel chamber 27a defined by a diaphragm 27c having a valve body. Fuel chamber 2
7a is connected to the pipe 26 and a pipe 28 communicating with the fuel tank 24, and the negative pressure chamber 27b is connected to the intake pipe 7.
A pipe line 29 communicating with the vicinity of the injection hole of the injection valve 10 is connected. Therefore, the pressure regulator 27 causes the injection valve 1
A part of the fuel is returned to the fuel tank 24 according to the negative pressure near the injection hole of 0, and the pressure of the fuel supplied to the injection valve 10 is adjusted.

Further, the engine 1 is provided with a throttle valve opening sensor 31 for detecting the opening of the throttle valve 9 and an engine water temperature sensor 32 for detecting the cooling water temperature of the cylinder 2. The detection signals of these sensors 31, 32 are supplied to the ECU 30 together with the detection signals of the intake air temperature sensor 11 and the TDC sensor 19. ECU30
Controls the valve opening timing and valve opening time of the injection valve 10 based on the detection signals of these sensors. The injection valve drive signal is output to open the injection valve 10 to operate the intake pipe 7 Fuel is injected into the inside.

Further, a recoil starter (not shown) is attached to an outer end portion on the flywheel 13 side in order to directly rotate the crankshaft 12 by manual operation at the time of starting.

Next, the operation of the engine configured as described above will be described. When the flywheel 13 fixed to the crankshaft 12 is rotated by manually operating the recoil starter, the cam 20 rotates and the fuel pump 22 is driven to pressurize the fuel. Simultaneously with the pressurization of the fuel, a voltage is generated in the winding wire 17 by the rotation of the flywheel 13, electric power is supplied to the ECU 30 through the power supply circuit 34, and the ignition coil in the ignition device unit 18 also has an ignition plug. A driving voltage is generated and the voltage is applied to the spark plug 4.

In the engine 1, a first magnet 14 and a winding wire 17 for obtaining electric power for driving an injection valve and a second magnet 15 and an ignition unit 18 for obtaining electric power for driving an ignition plug are independently provided. The large fluctuation of the power supply voltage of the ignition device for each ignition operation does not directly affect the power supply voltage for driving the injection valve. Therefore, the ignition operation and the fuel injection operation do not interfere with each other, and the injection valve 10 and the ignition plug 4 can be efficiently operated even with the energy of relatively small electric power based on the inertial rotation energy of the flywheel 13.

The fuel injection control at the time of starting in this embodiment will be described with reference to the timing chart of FIG.
In the figure, reference numerals t1 to t7 indicating the time from the start of cranking indicate the same timing as the same reference numerals in FIG.

The reset operation of the ECU 30 is started at the timing t1, and the reset operation is completed at the timing t4.
When the CU 30 starts up, the fuel injection valve activation signal is immediately turned on, and in response to the activation signal, the fuel injection valve terminal voltage is applied to the coil of the injection valve 10 and the fuel is injected.
After the first fuel injection time T1 has elapsed, the fuel injection valve activation signal is once turned off, and the fuel injection valve activation signal is turned on in response to the TDC pulse P1 at the first timing t6 after the rise of the ECU 30. Fuel is injected only during T2.

The fuel injection time T1 is set by a timer time setting. For example, the time set value of the timer is determined by a function of the temperature of the cooling water in the cylinder 2 detected by the engine water temperature sensor 32. That is, when the cooling water temperature is high, a short time is set to reduce the fuel injection amount, and when the cooling water temperature is low, a long time is set to increase the fuel injection amount.

The fuel injection time T1 is the detection timing t of the first TDC pulse P1 after the ECU 30 starts up.
The time may be set to be continuous with the fuel injection time T2 after 6, or an appropriate time up to the timing t6 may be set in advance.

On the other hand, after the ignition is successfully completed at the ignition timing t5 by the fuel injection of the fuel injection time T1 and the engine is started up, a preset pattern is set, that is, every time when the TDC pulse P1 is detected, according to a predetermined pattern. The injection valve 10 is opened for the determined fuel injection time T2 to inject fuel.

For example, the fuel injection time T2 is searched from a map stored in advance in the memory in relation to the value of the throttle opening sensor 31 and the engine speed. Further, a correction coefficient based on the engine temperature and a correction coefficient based on the degree of acceleration / deceleration of the engine are considered and determined as necessary.

Next, the fuel injection control at the time of engine stop operation in this embodiment will be explained with reference to the timing chart of FIG. The figure shows two control examples. One is that the fuel injection is continued by a control signal from the microcomputer even after the engine stop operation is performed, and the other one is that the fuel injection is also temporarily stopped when the engine stop operation is performed. Then, the fuel injection is restarted when the engine speed Ne falls below the planned speed.

First, in the first control example, the timing t8
Then, the engine is stopped by the operation of turning off the ignition (reference numeral IGN in the figure) switch (= turning off the power supply for ignition). At this time, the engine ignition device has not been operated yet, but the power supply is still secured by the energy generated by the rotational inertia of the flywheel, and the fuel injection valve control signal INJ1 is continuously output as it is. Therefore, based on the injection time read from the map stored in the memory of the ECU 30, the fuel continues to be injected at the scheduled timing.

Immediately before the engine rotation is completely stopped, that is, when the generator output voltage VACG reaches the minimum operating voltage V _E of the ECU 30 (timing t10), the output of the fuel injection valve control signal INJ1 is stopped. Fuel injection is also stopped.

On the other hand, in the second control example, when the ignition switch is turned off (timing t8), at the same time, the output of the fuel injection valve activation signal INJ2 is stopped. Therefore, fuel injection is also stopped at that time. After that, when the engine speed Ne has dropped to the planned value N _L (timing t9), the fuel injection valve start signal INJ is restarted.
2 output is started. That is, the engine speed is N _L
From this time (timing t9) to the time when the ECU 30 becomes inoperable (timing t10), fuel injection is performed according to the control signal output from the microcomputer.

Needless to say, the rotation speed NL at this time is set to a value equal to or higher than a value at which the power supply can be secured with sufficient power generation energy.

Next, referring to the functional block diagram of FIG.
A main function of the ECU 30 for performing the above control will be described. In FIG. 1, the timer 35 has a fuel injection time T
1 is set. The time set in the timer 35 is a value read from the time table 41 based on the water temperature of the cylinder 2 detected by the engine water temperature sensor 32, that is, the engine temperature.

The reset operation completion detecting section 37 is connected to the ECU 3
When the completion of the reset operation of 0 is detected, the detection signal s1 is output to the fuel injection valve starting unit 38. This detection signal s
In response to 1, the fuel injection valve starting unit 38 outputs the starting signal s2 to the terminal voltage supply unit 39. In this way, a predetermined terminal voltage is supplied from the terminal voltage supply unit 39 to the coil of the injection valve 10, and fuel injection is performed. The start command signal s1 is also supplied to the timer 35, and this signal s1 causes the timer 35 to operate.
Is activated and the time-up signal s3 is reached after a predetermined time (T1).
Is output. The fuel injection valve starting unit 38 stops outputting the starting signal s2 by the time-up signal s3, and the injection valve 10 is closed.

When the TDC pulse detection signal s4 is input from the TDC pulse detection unit 40, the fuel injection valve activation unit 38 outputs the activation signal s2 according to the fuel injection time data supplied from the map memory 36. The fuel injection time data output from the map memory 36 is a value determined as a function of the opening of the throttle valve, the engine temperature, the intake air amount, etc., and is stored in the map memory 36 in advance as a map. After starting up the microcomputer,
Fuel injection is performed at a predetermined injection timing based on the fuel injection time data.

When the timer 35 fails to start and the generator output voltage falls below a predetermined value, the timer value is reset, and when the generator output voltage rises above the predetermined value again, the time table 41 shows that the engine Read the time according to the temperature.

The values set in the time table 41 are
Until the engine is started successfully and the engine speed becomes equal to or higher than the predetermined value, the engine may be changed according to the number of repetitions of the starting operation until then, and the set value may be decreased as the number of times increases. By doing so, the amount of unburned debris retained can be suppressed even if the start failures overlap.

The engine stop control unit 42 performs fuel injection control when the engine is stopped. The engine stop control unit 42 receives an ignition switch on / off detection signal and a signal indicating the engine speed. Is entered. Then, based on the on / off detection signal of the ignition switch and the engine speed, a fuel injection valve activation permission / prohibition instruction signal for performing the operation shown in the timing chart of FIG. 4 is sent to the fuel injection valve activation unit 38. Supply. The fuel injection valve starting unit 38 outputs and stops the control output s2 in response to the start permission and prohibition instruction signal.

It should be noted that the fuel injection operation time restarted after the engine stop operation by changing the setting of the engine speed N _L which is a reference for outputting the fuel injection start signal INJ2 once output is stopped at the timing t8. Can be changed.

As described above, in this embodiment, EC
Immediately after the reset operation of U30 is completed, that is, immediately after the start-up of the microcomputer, the starting fuel can be injected. Further, after the engine is stopped, fuel injection is performed for a predetermined period until the generator output voltage VACG decreases and the ECU 30 becomes inoperable. The present invention does not necessarily need to include the control for injecting the starting fuel immediately after the completion of the reset operation.

[0051]

As is apparent from the above description, according to the present invention, fuel injection can be performed for a predetermined period even after the engine stop operation. Therefore, the recoil starter start operation is performed again with the engine just stopped. It is possible to improve the ignition performance when the ignition is performed. That is, the engine can be started without missing a few ignition timings (ignition opportunities).

Further, in the present invention, since the above-mentioned starting performance can be improved without complicating the structure of the fuel supply system, a general-purpose engine such as a small displacement engine adopting the recoil starter system. Even when applied to, it does not impair the characteristics of small size, light weight, and simple structure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main function of an ECU.

FIG. 2 is a configuration diagram of a general-purpose engine showing an embodiment of the present invention.

FIG. 3 is a timing chart showing a starting operation.

FIG. 4 is a timing chart showing an operation when the engine is stopped.

FIG. 5 is a timing chart showing the operation of the conventional device.

[Explanation of symbols]

1 ... Engine, 4 ... Spark plug, 7 ... Intake pipe, 1
0 ... Injection valve, 19 ... TDC sensor, 30 ... ECU,
31 ... Throttle valve opening sensor, 32 ... Water temperature sensor, 35 ... Timer, 36 ... Map memory, 37 ...
Reset operation completion section, 38 ... Fuel injection valve starting section, 39
... Terminal voltage supply unit, 40 ... TDC pulse detection unit, 4
2 ... Engine stop control unit

Claims (3)

[Claims] 1. A recoil starter, a fuel injection valve for supplying fuel to an intake passage of an engine, a microcomputer for controlling a valve opening time of the fuel injection valve according to an operating state of the engine, and an ignition device. In a batteryless electronic fuel injection control device for an engine, a power supply means for supplying electric power generated by rotation of a flywheel connected to a crankshaft of the engine to the fuel injection valve and the microcomputer, Fuel injection means for supplying fuel pressurized by a mechanical pump driven in conjunction with rotation to a fuel injection valve, and the ignition operation by the ignition device is stopped in response to an engine stop operation. After the ignition operation is stopped, fuel injection is performed for a predetermined period based on the control output from the microcomputer. A battery-less electronic fuel injection control device for an engine, which is configured to continue. 2. The scheduled period for continuing the fuel injection is:
2. The battery-less electronic fuel injection control device for an engine according to claim 1, wherein the period from when the ignition operation is stopped until the voltage supplied from the power supply means to the microcomputer drops to the minimum operating voltage of the microcomputer. . 3. The scheduled period for continuing the fuel injection is:
After the ignition operation is stopped, the period is started from the time when the voltage supplied from the power supply means to the microcomputer drops to a predetermined value, and is ended when the voltage drops to the minimum operating voltage of the microcomputer. The battery-less electronic fuel injection control device for an engine according to claim 1.