JP3014835B2 - Engine battery-less electronic fuel injection control device - Google Patents

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 battery-less electronic fuel injection control device for a small displacement engine without a battery.

[0002]

2. Description of the Related Art An electronic fuel system in which a fuel injection valve is disposed in an intake system of an engine, and a valve opening time of the fuel injection valve is controlled in accordance with an operation state of the engine to adjust a fuel injection amount. Injection devices are known.

[0003] In recent years, the application of the above-described electronic fuel injection device to a small displacement engine such as a general-purpose engine or an agricultural engine which is manually operated by a rope starter, that is, a recoil starter system without a power supply battery, has begun to be studied. I have.

In an electronic fuel injection system that does not use a battery, power is supplied from a generator attached to an engine during operation, and stable operation is performed. However, at the time of starting by the recoil starter, a sufficient power supply voltage to open the fuel injection valve cannot be obtained, and the fuel pressure is lower than that in the normal operation. With the control,
There is a problem in that a sufficient fuel injection amount for performing stable operation cannot be secured.

To solve this problem, Japanese Patent Laid-Open Publication No.
In Japanese Patent Publication No. 28, the following fuel injection device is proposed. This device is provided with a starting fuel supply device used only at the time of starting, and an engine starting operation detecting means which operates by a negative pressure in an intake passage when the engine is manually started. When the start of the engine is detected by the engine start operation detecting means, the fuel is supplied to the starting fuel supply device, and the fuel is ejected to the intake passage.

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

[0007]

The above-described injection device has the following problems. In the above-described injection device, it is necessary to provide a starting fuel injector, a communication pipe for detecting a negative pressure, and a negative pressure operating valve for fuel injection only at the time of starting. In a small displacement engine to which the recoil starter system is applied, such an increase in the number of attached components not only complicates the fuel supply system but also increases the size of the engine, which is not preferable.

Further, in the above-described injection device, since the fuel is supplied by the head pressure, there is a problem that the fuel supply pressure is not stable. In order to stably maintain a sufficient fuel supply pressure (fuel pressure), it is desirable to provide a pump that can supply the fuel by forcibly pressurizing the fuel. However, there still remains a problem that a sufficient amount of fuel cannot be injected at the time of starting.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a battery-less electronic fuel injection control device for an engine capable of securing a sufficient fuel injection amount at the time of starting without complicating and enlarging the configuration of a small displacement engine without a battery.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, the present invention provides a method of starting a flywheel connected to a crankshaft of an engine by a start operation by a recoil starter. Power supply means for supplying power generated by the fuel injection valve for driving and controlling the fuel injection valve, and fuel supply means for supplying fuel pressurized by a mechanical pump driven in conjunction with rotation of the flywheel to the fuel injection valve And a control means configured to drive the fuel injection valve for a period corresponding to the cranking by the start operation after the start operation is started and for a valve opening time longer than that during the self-sustaining operation. There is a feature in the point.

[0011]

According to the present invention having the above-described features, the valve opening time during the engine start operation, that is, during cranking, is longer than the valve opening time after cranking, that is, during the self-sustaining operation of the engine. Therefore, during the cranking period, a sufficient amount of fuel necessary for starting the engine can be injected, and the starting performance of the engine can be improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 2 is a diagram showing a configuration of an engine according to one embodiment of the present invention. In the figure, a piston 3 and a spark plug 4 are arranged in a cylinder 2 of an engine 1. An intake valve 6 is provided at an intake port 6 opened at an upper portion 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 for detecting intake air temperature are arranged upstream of the throttle valve 9. Injection valve 10
Thus, fuel is injected into the intake pipe 7 upstream of the throttle valve 9.

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.
At positions facing the first magnet 14, six protrusions 16 a provided on the stator core 16, and protrusions 16 a
And a power generating winding portion composed of a winding 17 wound around the winding.

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

On the other hand, at a position facing the second magnet 15, an ignition device unit 18 including an ignition coil is provided. The igniter unit 18 is connected to the ignition plug 4 via a conductor 33. In addition, the ignition device unit 18 in the present embodiment is constituted by a self-triggering 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 disposed above the cylinder 2. A pulley 20a is fixed to a shaft 21 of the cam 20, and a timing belt (not shown) is provided between the pulley 20a and the crankshaft 12, and the cam 20 is driven by 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 TDC timing is provided at a position facing the third magnet 20b.

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

The fuel pressurized by the fuel pump 22 is supplied to the line 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
A pipe 29 communicating with the vicinity of the injection hole of the injection valve 10 is connected. Therefore, the injection valve 1 is controlled by the pressure regulator 27.
A part of the fuel is returned to the fuel tank 24 in accordance with the negative pressure near the injection hole of 0, and the pressure of the fuel supplied to the injection valve 10 is adjusted.

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. ECU 30
Controls the opening timing and opening time of the injection valve 10 based on the detection signals of these sensors, outputs an injection valve drive signal to open the injection valve 10, and controls the intake pipe 7. Inject fuel inside.

Further, a recoil starter (not shown) is attached to the outer end of the flywheel 13 for directly rotating 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 17 by the rotation of the flywheel 13, electric power is supplied to the ECU 30 via the power supply circuit 34, and an ignition plug in the ignition device unit 18 is also provided. A driving voltage is generated, and a voltage is applied to the ignition plug 4.

In the present embodiment, the first magnet 14 and the winding 17 for obtaining the power for driving the injection valve, and the second magnet 15 and the ignition device unit 18 for obtaining the power for driving the spark plug are independently provided. Therefore, a 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 injection valve 10 and the spark plug 4 can be operated efficiently even with relatively small energy based on the inertial rotational energy of the flywheel 13 without the interference between the ignition operation and the fuel injection operation.

Next, the fuel injection control in this embodiment will be described with reference to the timing chart of FIG. 3A shows a state of a change in the power supply voltage supplied to the ECU 30, and FIG. 3B shows a state of a change in the pressure of the fuel discharged from the fuel pump 22. (C) shows a shaped waveform of an output signal of the TDC sensor 19, that is, an ignition timing pulse. Further, FIG. 3D shows a valve opening voltage supplied to the injection valve 10, for example, a voltage applied to a valve opening drive solenoid, and FIG. 3E shows a voltage flowing to the drive solenoid. Indicates current. In the figure, Tis
Is the fuel injection time at the start, and Ti is the fuel injection time during the self-sustaining operation.

As shown in FIG. 3, after the manual operation by the recoil starter is performed, until the power supply voltage supplied to the ECU 30 reaches a specified voltage (for example, 14.5 volts), and the fuel pressure becomes a specified pressure (for example, 1.0kg / c
It takes some time to reach m ² ).

Therefore, in this embodiment, the cranking period until the power supply voltage and the fuel pressure reach the specified values and the self-sustaining operation period after the cranking period elapses are:
The setting of the valve opening time has been changed.

First, during the self-sustaining operation period, the fuel injection time Ti is calculated by the following equation. Ti = KTW × KACC × Tib (1) In the calculation formula (1), the symbol KTW is a water temperature correction coefficient, and is a value preset in a memory in the ECU 30 according to the water temperature of the cylinder 2. This water temperature correction coefficient KT
W is read from the memory to the CPU based on the detection signal from the engine water temperature sensor 32.

The symbol KACC is an acceleration / deceleration correction coefficient for compensating for a transient fuel shortage caused by a sudden change in the opening of the throttle valve 9. This correction coefficient K
The ACC is also stored in the memory, and the CP
A value corresponding to the amount of change obtained from the value of the throttle valve opening sensor 31 read into U is selected.

Reference numeral Tib denotes a basic fuel injection time, which is determined by searching a map of the value of the throttle opening sensor 31 and the engine speed. This map is also stored in the memory in advance. The engine speed is calculated from the reciprocal of the output interval of the TDC sensor 19.

On the other hand, the fuel injection time Tis during the cranking period is calculated by the following equation. Tis = KTW × FSTFI (2) In the formula (2), the symbol FSTFI is a starting fuel injection time. Is not a search from the map, but a preset fixed value. Then, the starting fuel injection time FS
The TFI is set as a fixed value that is much larger than the basic fuel injection time Tib. According to the experimental results of the present inventors, the maximum value of the fuel injection time during the independent operation is 1
0 ms, whereas the starting fuel injection time FSTFI
Gave good results in 20 ms.

The end of the start control period in which the fuel is injected based on the set fuel injection time calculated by using the calculation formula (2) is determined based on the output signal of the TDC sensor 19. For example, a means for counting the number of output signals of the TDC sensor 19 is provided, and the time when the counted value reaches a predetermined value is defined as the end time of the start control period. Therefore, after the end of the start control period, the valve opening time of the injection valve 10 is determined by the fuel injection time Ti obtained by the above equation (1), and the self-sustaining operation is performed.

Next, referring to the functional block diagram of FIG.
The main functions of the ECU 30 for performing the above control will be described. Note that the ECU 30 includes a TDC sensor 19 of 1-2.
At the time when the output signal is issued about once, sufficient electric power for control is supplied.

In FIG. 1, the valve opening time calculation section 35
The opening time of the injector 10 during the self-sustaining operation is calculated, and a valve drive signal is output to the injector 10 via the switching unit 36. The valve opening time calculation unit 35 includes a water temperature correction coefficient KTW read from the water temperature correction coefficient storage unit 37 according to the value of the water temperature sensor 32 and an acceleration / deceleration correction coefficient storage unit according to the amount of change in the value of the throttle valve opening sensor 31. The acceleration / deceleration correction coefficient KACC read out from 38, the basic fuel injection time Tib read out from the basic injection time storage unit 39 in accordance with the engine speed obtained from the value of the throttle valve opening sensor 31 and the output interval of the TDC sensor 19, Is supplied. And
Based on these supplied values, the valve opening time is calculated using the above-described calculation formula (1).

The starting valve opening time calculation section 40 calculates the valve opening time at the time of starting, and sends it to the injection valve 1 via the switching section 36.
A valve drive signal is output to 0. A water temperature correction coefficient KTW is supplied to the start-time valve opening time calculation section 40, and the starting fuel injection time FSTFI (fixed value) is multiplied by the water temperature correction coefficient using the above-described calculation formula (2) to start the engine. The valve opening time is calculated.

The switching section 36 is switched to the valve opening time calculating section 40 at the time of starting, and is switched to the valve opening time calculating section 35 in response to the count end signal of the counter 41.

In the injection timing detector 42, the TDC sensor 1
9 to detect the injection timing. When the output signal of the TDC sensor 19 is detected, the detection signal is output to the start-time valve opening time calculation unit 40, and the start-time valve opening time calculation unit 40 responds to this detection signal to open the valve as described above. The time, that is, the fuel injection time is calculated. The counter 41
The counter value is decremented each time the valve drive signal output from the start-time valve opening time calculation unit 40 is turned off. When the counter 41 is decremented by a predetermined counter value, a count end signal is output. .

The switching unit 3 responds to the count end signal.
When 6 is switched to the valve opening time calculation section 35, the valve drive signal is supplied to the injection valve 10 for the time calculated by the valve opening time calculation section 35 assuming that the self-sustaining operation start time has been reached.

The counter value set in the counter 41 may be selected according to the temperature of the engine, that is, the temperature of the engine water. For example, considering the ease of starting the engine depending on the temperature, the counter value may be decreased when the engine water temperature is high, and the counter value may be increased when the engine water temperature is low.

In this embodiment, the TDC sensor 19 is used. However, it is possible to use the ignition signal of the ignition device unit 18 without using the TDC sensor 19.

As described above, in this embodiment, until the power supply voltage and the fuel pressure reach the specified values, the fuel is injected according to the fuel injection time set longer than in the self-sustaining operation. In addition, a sufficient amount of fuel can be supplied even in the initial stage of the manual operation by the recoil start method.

[0040]

As is apparent from the above description, according to the present invention, a sufficient amount of fuel can be supplied even in the early stage of starting an engine whose fuel pressure is unstable, and the starting performance can be improved. it can.

Further, in the present invention, the above-described improvement of the starting performance can be achieved without complicating the structure of the fuel supply system, so that a small displacement engine such as a small displacement engine employing a recoil starter system can be provided. Even when applied to a general-purpose engine, the characteristics of small size, light weight, and simple structure are not impaired.

[Brief description of the drawings]

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

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

FIG. 3 is a timing chart showing the operation of the embodiment.

[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: valve opening time calculation unit, 40: valve opening time calculation unit at startup, 41: counter, 42: injection timing detection unit

Continuation of front page (56) References JP-A-63-170528 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) F02N 17/08 F02D 41/06 330 F02N 3/02

Claims (3)

(57) [Claims] When a flywheel connected to a crankshaft of an engine is rotated by a start operation by a recoil starter, power supply means for supplying electric power generated by the rotation for driving and controlling a fuel injection valve; Fuel supply means for supplying fuel pressurized by a mechanical pump driven in conjunction with the rotation of the flywheel to a fuel injection valve; after the start operation is started, a period corresponding to cranking by the start operation is independent. A control unit configured to drive the fuel injection valve with a valve opening time set longer than during operation, and a battery-less electronic fuel injection control device for an engine. 2. A period corresponding to the cranking is T
2. The battery-less electronic fuel injection control device for an engine according to claim 1, wherein the setting is made based on the number of signal outputs from a sensor for detecting the number of DCs. 3. The battery-less electronic fuel injection of an engine according to claim 2, wherein at least one of the number of signal outputs from the sensor for detecting the number of TDCs and the valve opening time is selected according to the engine temperature. Control device.