JP3091023B2 - 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.

In recent years, the application of the electronic fuel injection device to small-displacement engines, such as general-purpose engines and agricultural engines, which do not have a power supply battery and are manually started by a rope starter, that is, a recoil starter system, has begun to be studied.

In an electronic fuel injection system that does not use a battery, an electronic control unit (hereinafter referred to as an ECU) including a microcomputer is operated during operation by a generator attached to the engine.
), Sufficient power is supplied, and stable operation is performed. However, when 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 start of the cranking by the recoil starter starting operation, the engine speed Ne rapidly increases, the generator output voltage VACG induced by the rotation of the engine flywheel also sharply increases, and the inertia of the flywheel increases. When the rotation speed exceeds a predetermined value, a substantially stable voltage range is reached. Thereafter, when the start is successful, the engine speed Ne further increases as shown by the solid line a, and the engine is operated by itself, and the generator output voltage VACG is maintained at a substantially constant value. If the engine fails to start, the engine speed N
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 an injection valve activation signal. When the injection valve activation signal is supplied, a predetermined terminal voltage is applied to the fuel injection valve in response to this, 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 (when the pulse P2 is generated), and the engine starts its own operation.

By the way, as shown, the generator output voltage falls to the ECU is reset operation at the timing t1 has reached the minimum operating voltage V _E of the ECU, the time until the timing t4 to stand up and reset is complete Because of this,
In this ECU, at the timing t3 before that, TDC
Pulse P1 is not detected. On the other hand, at the subsequent timing t6, since the reset operation is completed and the ECU has started up, the TDC pulse P1 is detected, and in response to this, the 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 start operation by the recoil starter is determined based on the generator output voltage shown in FIG. There will be only one at t6. Therefore, there is a problem that the possibility of successful start is reduced and the number of times of repeated start operations due to failure of start is increased. The fuel injection valve reaches the minimum operating voltage V _J at the timing t2.

On the other hand, Japanese Patent Application Laid-Open No. Sho 63-170528 discloses a starting fuel supply used only at the time of starting, and detecting an engine starting operation which is operated by a negative pressure in an intake passage when the engine is manually started. A fuel injection device provided with means has been proposed. In this fuel injection device,
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 fuel injection device, the starting fuel injector is not opened by using 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 is supplied with fuel by head pressure.

In the fuel injection device described in Japanese Patent Application Laid-Open No. 63-259129, the control of the microcomputer is not performed until the engine starts operating by itself.
An operating power is supplied to the fuel injection valve by another route, the fuel injection valve is opened, and the starting fuel is injected.

[0012]

The above-described 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 communication pipe for negative pressure detection, and a negative pressure operating valve for fuel injection only at the time of starting. The increase in such accessory components in small displacement engines 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 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.

On the other hand, in the fuel injection device described in the latter publication, fuel is injected without control of the microcomputer until the start of the engine 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. In addition, when cranking is repeated in a restart operation due to a failure in starting, a large amount of unburned gas stays in the cylinder, and the difficulty of ignition gradually increases.

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 an appropriate fuel injection amount at the time of starting without complicating and enlarging the configuration of a small displacement engine without a battery.

[0016]

Means for Solving the Problems The above problems are solved,
According to the present invention, when a flywheel connected to a crankshaft of an engine is rotated by a start operation by a recoil starter, power generated by the rotation is supplied for driving and controlling a fuel injection valve. Power supply means, fuel supply means for supplying fuel pressurized by a mechanical pump driven in conjunction with the rotation of the flywheel to the fuel injection valve, and the microcomputer until the microcomputer for controlling the fuel injection valve is started; The voltage that appears on the reset input line of the computer starts resetting
Outputs injection valve activation signal to the fuel injection valve when it reaches the voltage, the power supply means the injection valve activation signal is being output
This voltage is reached when the voltage of
It is configured to open the fuel injection valve and inject fuel
It is characterized by having a fuel injection valve control means.

[0017]

According to the present invention having the above-described features, at the beginning of cranking, regardless of whether or not the fuel injection timing detection signal is input, it is easy to confirm immediately before the microcomputer rises based on the voltage appearing on the reset line of the microcomputer. Then, a valve opening instruction is output. As a result, without waiting for the microcomputer to rise, the voltage appearing on the reset line reaches the predetermined value, but if the power supply voltage is earlier than the minimum operating voltage of the fuel injector, the power supply voltage becomes the minimum of the fuel injector. When the operating voltage is reached, the voltage appearing on the reset line also reaches the predetermined value, but when the power supply voltage reaches the minimum operating voltage of the fuel injector later, the voltage appearing on the reset line rises to the predetermined value. Since the starting fuel is injected at the time of reaching, the ignition timing which is rare in the cranking time is not missed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 5 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. Fuel is injected by an injection valve 10 upstream of the throttle valve 9 in 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 and outer circumferences 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 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 the 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 pipe 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.

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

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 engine 1, a first magnet 14 and a winding 17 for obtaining electric power for driving the injection valve, and a second magnet 15 and an ignition device unit 18 for obtaining electric 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 at the time of starting in this embodiment will be described with reference to the timing chart of FIG. 6, reference numerals t1 to t7 indicating the time from the start of cranking indicate the same timings as the same reference numerals in FIG.

[0030] the generator output voltage VACG reaches ECU30 operating voltage V _E (see FIG. 6), the timing t1
Then, the reset operation of the ECU 30 is started, and at the same time, the injection valve activation signal is turned on. At this point, the injection valve 10 does not yet generator output voltage VACG reaches the minimum operating voltage V _J of the injection valve 10 is not opened. Minimum operating voltage sufficient terminal voltage to the coil is applied injection valve 10 of the injection valve 10 at time t2 it reaches the V _J of the generator output voltage VACG the injection valve 10 is turned on, fuel is injected.

After the reset of the ECU 30 is completed, the ECU 3
When 0 rises (timing t4), the injection valve activation signal is turned off, and accordingly, the terminal voltage applied to the coil of the injection valve 10 is also turned off, and the fuel injection is stopped.

After the reset is completed and the ECU 30 starts up, the fuel injection valve 10 is opened for the fuel injection time determined according to the predetermined injection pattern at a preset timing, that is, every time the TDC pulse P1 is detected, and the fuel is opened. Inject. At the first timing t6 after the startup of the ECU 30, the injection valve activation signal is turned on in response to the TDC pulse P1, and fuel is injected only during the time T2.

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

In the above-described example, the first fuel injection is stopped at the same time as the reset signal is turned off. However, under the use condition in which the fuel injection amount is considered to be insufficient, the first fuel injection is further stopped after the reset operation is completed, that is, the first fuel injection is completed. After fuel injection,
The fuel may be injected only for a required time. For example, when the reset operation is completed, an injection valve activation signal is output, and at the same time, a timer is activated, and the injection valve activation signal is continuously output until the time is up.

The time set in the timer may be determined by a function of a parameter indicating the engine state such as the temperature of the cooling water in the cylinder 2 detected by the engine water temperature sensor 32, that is, the engine temperature. For example, 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.

FIG. 3 shows an example of the timing when the fuel injection is additionally performed after the first fuel injection. In the figure, a time point t4 when the reset operation of the ECU 30 is completed
The output of the injection valve activation signal is temporarily stopped (turned off). Thereafter, the injection valve activation signal is turned on again for the time T1. The fuel injection time T1 may be set as a time continuous with the fuel injection time T2 after the detection timing t6 of the first TDC pulse P1 after the rise of the ECU 30, or at the timing t6.
An appropriate time until the time may be set in advance.

Next, the main hardware configuration of the ECU 30 for performing the operation shown in the timing chart of FIG. 2 will be described. In the circuit diagram of FIG. 1, the stabilized power supply circuit 35 stabilizes the power supplied from the power supply circuit 34 for microcomputer control, and supplies
Supply to the power terminal. Further, the stabilized power supply circuit 35 generates a reset signal for the microcomputer 36, and supplies the reset signal to the reset terminal of the microcomputer 36 which is configured to be "L" active in this embodiment.

The port of the microcomputer 36 is connected to the input side of the pre-driver 37, and the output side of the pre-driver 37 is connected to the input side of the driver 38. further,
The output side of the driver 38 is a drive coil 10a of the injection valve 10.
And the other end of the drive coil 10 a is connected to the power supply circuit 34.

Further, the reset signal line of the stabilized power supply circuit 35 is connected to the input side of the starting pre-driver 39, and the output side of the starting pre-driver 39 is connected to the input side of the driver 38.

In the above configuration, during the normal operation in which the reset operation is completed, the pre-driver 37 is energized by the injection valve activation signal output from the port, and as a result, the driver 38 is energized and the drive coil is energized. A current is supplied to the power supply circuit 10a from the power supply circuit 34, and the injection valve 10 is opened.

On the other hand, the control signal is not output from the port of the microcomputer until the reset operation is completed after the reset is started when the engine is started. Therefore, until the reset operation is completed, instead of this control output, the starting pre-driver 39 is energized by the voltage appearing on the reset signal line, and the driver 38 is energized by the output signal.
Immediately after the start of the reset operation, the injector 10 does not open because the generator output voltage VACG is low.
There fuel is injected by opening when it reaches the minimum operating voltage V _J of the injection valve 10 (the timing t2).

When the reset signal line changes to high (H) and the reset operation ends, the starting pre-driver 39 stops operating, and thereafter, fuel injection is performed according to the control output from the port of the microcomputer 36. Will be.

On the other hand, the operation shown in FIG. 3 is performed by software processing of the microcomputer after the microcomputer has started up. With reference to a functional block diagram of FIG. 4, a description will be given of a main function of the ECU 30 for controlling the operation shown in FIG.

In FIG. 4, the fuel injection time T1 is set in a timer 40. The time set in the timer 40 is based on the water temperature of the cylinder 2 detected by the engine water temperature sensor 32, that is, the engine temperature.
Is the value read from.

The reset operation completion detecting section 42 is provided by the ECU 3
It detects that the reset operation of 0 has been completed, and outputs a detection signal s1 to the fuel injection valve activation unit 43. This detection signal s
In response to 1, the fuel injector startup unit 43 outputs a startup signal s2 to the terminal voltage supply unit 44. Thus, a predetermined terminal voltage is supplied to the coil of the injection valve 10 from the terminal voltage supply unit 44, and fuel injection is performed. The start command signal s1 is also supplied to the timer 40.
Operates, and after a predetermined time (T1), the time-up signal s3
Is output. In response to the time-up signal s3, the fuel injection valve activation unit 43 stops outputting the activation signal s2, and the injection valve 10 closes.

When the TDC pulse detection signal s4 is input from the TDC pulse detection unit 45, the fuel injection valve starting unit 43 outputs a start signal s2 based on the fuel injection time data supplied from the map memory 46. The fuel injection time data output from the map memory 46 is a value determined as a function of the degree of opening of the throttle valve, the engine temperature, the amount of intake air, and the like.
6 is stored. After the start of the microcomputer, fuel injection is performed at a predetermined injection timing based on the fuel injection time data.

When the timer 40 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 indicates the current time. At a time corresponding to the engine temperature.

The values set in the time table 41 are as follows:
Until the start is successful and the engine reaches or exceeds the predetermined number of revolutions, change according to the number of times the start operation has been repeated,
The setting value may be configured to decrease as the number of times increases. By doing so, the amount of stagnation of unburned gas can be suppressed even if starting failures overlap.

In this embodiment, the case where the minimum operating voltage of the injector is higher than the operating voltage of the ECU has been described.
The relationship between the two may be reversed. In this case, the valve is opened and fuel is injected at the same time as the start of the reset operation.

As described above, in this embodiment, the EC
When the reset operation of U30 is started, the fuel for starting can be injected from the start to immediately before the reset operation of the microcomputer is completed. Further, if necessary, the fuel injection for starting can be performed for a predetermined time immediately after the completion of the reset operation.

[0051]

As is apparent from the above description, according to the present invention, since the starting fuel can be injected immediately before the microcomputer starts up, the engine can be started without missing a few ignition chances during the cranking period. .

Since the timing immediately before the start of the microcomputer is obtained from the reset signal line supplied to the microcomputer without providing a special arithmetic circuit or sensor, the configuration can be simplified.

Further, in the present invention, the above-described improvement in 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 circuit diagram showing a hardware configuration of a main part of an ECU.

FIG. 2 is a timing chart showing an example of a starting operation.

FIG. 3 is a timing chart showing a modification of the starting operation.

FIG. 4 is a block diagram illustrating main functions of an ECU.

FIG. 5 is a configuration diagram of a general-purpose engine showing one embodiment of the present invention.

FIG. 6 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, 37: pre-driver, 38: driver, 39
... Starting pre-driver, 40 ... Timer, 42 ... Reset operation completion unit, 43 ... Fuel injection valve starting unit, 44 ... Terminal voltage supply unit, 45 ... TDC pulse detection unit, 46 ... Map memory

Continuation of front page (56) References JP-A-4-43843 (JP, A) JP-A-6-2586 (JP, A) JP-A-63-195346 (JP, A) JP-A-55-146241 (JP) , A) Japanese Patent Publication No. 5-52419 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/00-41/40 F02D 43/00-45/00

Claims (5)

(57) [Claims] 1. A microcomputer for controlling a recoil starter, a fuel injection valve for supplying fuel to an intake passage of an engine, and a valve opening time of the fuel injection valve according to a predetermined injection pattern according to an operation state of the engine. In a battery-less electronic fuel injection control device for an engine, when a flywheel connected to a crankshaft of the engine is rotated by a start operation by a recoil starter, the power generated by the rotation is used to drive and control the fuel injection valve. Power supply means for supplying fuel, fuel supply means for supplying fuel pressurized by a mechanical pump driven in conjunction with the rotation of the flywheel to the fuel injection valve, and a microcomputer for controlling the fuel injection valve Until the voltage that appears on the reset input line of the microcomputer is reset When the start voltage is reached, an injection valve start signal is output to the fuel injection valve , and this injection valve start signal is output.
And a fuel injection valve control means configured to open the fuel injection valve and inject fuel when the voltage of the power supply means has reached the operating voltage of the fuel injection valve. A battery-less electronic fuel injection control device for an engine. 2. The apparatus according to claim 1, further comprising a control unit configured to open the fuel injection valve for a predetermined time immediately according to a control output of the microcomputer to perform fuel injection immediately after the microcomputer is started. The battery-less electronic fuel injection control device for an engine according to claim 1, wherein 3. The battery-less electronic fuel injection control device for an engine according to claim 2, wherein the scheduled time is a time set in a timer in advance. 4. The battery-less electronic fuel injection control device for an engine according to claim 2, wherein the time set in the timer is determined based on a cooling water temperature of the engine. 5. The time set in the timer is determined based on the number of consecutive start operations performed until the engine speed reaches a predetermined speed or more. The battery-less electronic fuel injection control device for an engine according to claim 2.