JPS6014185B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection system, and more particularly to an improved fuel injection system for starting an internal combustion engine.

Conventional electronically controlled fuel injection systems use a solenoid valve (hereinafter referred to as the main injector) installed in each cylinder of the engine to improve starting performance when the cooling water temperature of the internal combustion engine is low.
In addition, one or more cold start injectors are installed in the intake pipe at a position away from the cylinders of the engine, and the injection time of the cold start injectors is determined to be approximately constant, and the start The engine is equipped with a thermo-time switch that disables the cold start injector to prevent the plug from covering even if the engine is turned continuously.

In this way, conventional systems require a cold start injector and a thermo-time switch, which are structurally complex and expensive, only for starting the engine, and also require fuel piping to the cold-start injector and thermo-time switch. Due to electrical wiring to the switch, etc., it is disadvantageous not only in terms of cost but also in terms of repair. Furthermore, since a large amount of fuel remains in the intake pipe of the engine during engine operation, and some of it evaporates and is sucked into each cylinder to start the engine, some of the fuel remains in the intake pipe even after starting. Since it remains in the intake pipe of the engine and is gradually inhaled after the engine has been started, it has the disadvantage that the exhaust gas deteriorates (in particular, the amount of HC in the exhaust gas increases).
The present invention solves the above-mentioned drawbacks; when the rotational speed is below the first set rotational speed, the fuel injection amount is constant regardless of the rotational speed, and when the rotational speed is above the first set rotational speed, the fuel injection amount is related to the rotational speed. Furthermore, when the rotation speed is lower than the second set rotation speed, which is higher than the first set rotation speed, and the starter is being driven, the amount of fuel injection is greatly increased depending on the engine temperature, and the starter drive time is increased. By stopping this increase when the fuel injector exceeds the set time, it is possible to start the engine in a short time using only the main injector, and even if the engine cannot be started, it is possible to prevent plug fogging etc. The object is to provide a controlled fuel injection device.

An embodiment of the present invention shown in the drawings will be described below.

In FIG. 1, reference numeral 1 denotes a primary side terminal of an ignition coil for detecting engine rotational signals as pulse signals, and 2 denotes a waveform shaping circuit that shapes the waveform of the pulse signals to prevent malfunctions. 3 is a frequency dividing circuit, and in the case of a 6-cylinder engine, an electromagnetic injection valve 1 is used as the main injector that injects fuel with one revolution of the engine.
In order to operate the electromagnetic injection valve 11 once, a frequency divider circuit is used, and if the electromagnetic injection valve 11 is to operate more than once per engine revolution, a circuit with a different frequency division ratio is required. Of course.

4 is an arithmetic circuit which inputs the rotation signal from the frequency dividing circuit 3 and the signal corresponding to the intake air amount from the intake air amount meter 5, and calculates the time width tp calculated by dividing the intake air amount of the engine by the engine speed. A pulse signal T is generated.

This time width tp is proportional to the amount of air sucked into one cylinder in one stroke. 6 is a multiplication circuit which calculates various signals from the operating state detection means 7 for detecting engine cooling water temperature, intake air temperature, etc., based on the pulse time of the pulse signal T outputted from the arithmetic circuit 4. Then, a pulse signal L having a pulse time width tm is output.

8 is a voltage correction circuit which inputs the pulse signal T2 from the multiplication circuit 6, corrects the change in the fuel injection amount of the electromagnetic injection valve 11 depending on the power supply voltage, and generates a pulse with a pulse duration tu according to the power supply voltage. Outputs signal L.

Reference numeral 9 denotes an OR circuit which receives pulse signals T, L, T3 from the arithmetic circuit 4, the multiplication circuit 6, and the voltage correction circuit 8.
is input, and the output circuit 10' synthesizes a pulse signal T having a pulse time width (tp+tm+tu).

Furthermore, in FIG. 2, reference numeral 12 is a terminal for detecting the driving state of a star starter (not shown), and when a signal indicating star starter drive is input to the terminal 12, the cooling detected by the operating state detecting means 7 is detected. The fuel increase circuit 13, which determines the fuel increase ratio according to the water temperature signal, operates.

A monostable multipipe layer 14 and a comparator circuit 15 are connected to the frequency divider circuit 3, and the comparator circuit 15 receives a pulse signal having a time width inversely proportional to the engine speed input from the frequency divider circuit 3 and this pulse. The operation of the increase circuit 13 is controlled by comparing it with a pulse signal of a constant time width inputted from the monostable multipipelator 14 in synchronization with the signal. That is,
The comparison circuit 15 determines whether the engine rotation speed is a set rotation speed (for example, 40
The output signal of the increase circuit 13 is controlled to be input to the arithmetic circuit 6 only in the case where the increase circuit 13 is equal to or higher than pm). Reference numeral 16 denotes a time limit circuit for detecting the driving time of the starter, which stops the operation of the increase circuit 13 when the starter driving time has elapsed for a predetermined time according to the engine temperature after the start of driving.

The output circuit 10 controls the electromagnetic injection valves 11 installed in each cylinder of the internal combustion engine according to the time width (tp+tm+tu) of the pulse signal T.
) is operated to supply the optimum amount of fuel to the internal combustion engine according to the operating condition, and the arithmetic circuit 4
For example, a multi-pipelator with a variable pulse time width, which is disclosed in Tokusekki Publication No. 49-97016, is used.

Then, the charging of the capacitor is controlled by the pulse signal from the frequency dividing circuit 3, and its discharging is controlled by the air flow meter 5. As described in the above publication and is well known, the time width of the pulse signal from the frequency dividing circuit 3 is inversely proportional to the engine rotational speed, so the circuit constants of the arithmetic circuit 4 are appropriately selected. By doing this, the charging voltage of the capacitor is saturated at low rotation speeds, and when the engine rotation speed is below the first set value (for example, 128 pm), the pulse time width tp can be made constant with respect to the rotation speed. The pulse signal T generated by the arithmetic circuit 4
, is constant with respect to the rotation speed when the rotation speed is below the first set rotation speed (128 pm), and is inversely proportional to the rotation speed when the rotation speed is higher than that. FIG. 2 shows the detailed configuration of the operating state detection means 7, the increase circuit 13, the comparison circuit 15, and the time limit circuit 16.

As shown in the figure, the increase circuit 13 includes capacitors C, diodes D, ~D5, resistors R, ~R9, transistors Tr,
, Tr2, and Tr3, the comparator circuit 15 includes an inverter 151 and a D-flip-flop 152, and the operating state detection means 7 includes a thermistor 70 for water temperature detection,
The time limit circuit 16 is composed of resistors R,o to R,2 and transistor Tr4, and comparator 160, and resistors R2o to R2.
5, Diode D2o~○24, Transistor Tt2o
, Tr2,, capacitor C2. It consists of In the operating state detection means 7, the resistance value of the thermistor 70 increases as the engine cooling water temperature decreases, so the emitter potential of the transistor T4 connected to the resistor 2 as an emitter follower increases as the cooling water temperature decreases.

On the other hand, in the increase circuit 13, while a starter (not shown) is being driven, a high-level voltage starter signal is input to the terminal 12, thereby making the transistor Tr conductive. Due to the conduction of the transistor Tr, the transistor T2 and the transistor T are also conductive, and during the starter drive, the currents 1 and 12 flow through the transistor T
r2 and flows through transistor Tr3. Here, the voltage applied to the emitters of the transistors Tr2 and Tr3 is not the constant power supply voltage V8, but the voltage across the resistors R and 2 of the operating state detection means 7, so the higher the emitter potential of the transistor Tr4, the more the current 1,,1
2 becomes larger. That is, the current 1 increases as the temperature of the cooling water decreases. The operation of this increase circuit 13 is controlled by a comparator circuit 15 and a timer circuit 16.

The monostable multi-pipe plate 14 receives a pulse signal from the frequency dividing circuit 3 with a time width to that is inversely proportional to the engine speed, and each time the pulse signal is input, the monostable multi-pipe plate 14 outputs a pulse signal with a fixed time width. generates a pulse signal. This time width ts is the second set value of the engine rotation speed (40 pm)
The pulse signal with a time width ts is input to the data terminal D of the D-flip-flop 152 of the comparison circuit 15. On the other hand, D-flip-flop 152
A pulse signal obtained by inverting the pulse signal from the frequency dividing circuit 3 by an inverter 151 is input to the clock terminal CLOCN of the clock terminal CLOCN. When the engine speed is lower than the second set speed, the pulse time width To becomes larger than the wide pulse time width, so the D-flip-flop 152
Produces a high level voltage at the output terminal. Conversely, when the engine speed is higher than the second set speed, the pulse time width to becomes smaller than the pulse time width ts, so the D flip-flop 152 applies a low level voltage to the Q output terminal. arise. As a result, transistors Tr2 and Tr of the increase circuit 13
The current flowing through diodes D3 and D4 flows into the multiplier circuit 6 through diodes D3 and D4 only when the comparator circuit 15 is producing a high level voltage, but when the comparator circuit 15 is producing a low level voltage. When the signal is present, the signal flows to the comparator circuit 15 via the diodes D2 and D5, and therefore does not flow to the multiplier circuit 6. In other words, a large amount of power flows from the increase circuit 13 to the multiplication circuit 6 only when the engine speed is equal to or lower than the second set speed (40 pm).

On the other hand, the capacitor C2o of the time limit circuit 16 has a resistor R2,
It is charged through the diode D22 in proportion to the emitter potential of the transistor Tr4 of the operating state detecting means 7, and the comparator 160 generates a low level voltage and the transistor Tr22 is cut off.

In this state, when a high level voltage is applied to the terminal 12 at the same time as starting the starter drive, the transistor Tr becomes conductive, so the capacitor C2o is no longer charged, and the capacitor C2o discharges through the transistor T and the resistor R22. . This discharge continues while the starter is running, and when the starter drive time becomes longer and the voltage across the capacitor C2o falls below the set voltage determined by the resistors R23 and R24, the comparator 160 generates a low level voltage. Therefore, the transistor Tr22 is suitable. Therefore, if the collector terminal of the transistor Tr22 is connected to the cathodes of the diodes D2 and D5 of the increase circuit 13, the currents 1, 12 will stop flowing if the starter drive time continues for a predetermined period or more. Needless to say, this predetermined time period changes depending on the engine cooling water temperature. The multiplier circuit 6 to which the currents 1, 12 are inputted is configured as, for example, a variable time width multipipulator described in Japanese Patent Application Laid-Open No. 49-67016.

This multipipulator has a capacitor that is charged during the pulse time width 2 of the pulse signal T from the arithmetic circuit 4, and produces a pulse signal T2 with a pulse time width tm equal to the discharge duration after the charging is completed. The pulse time width t increases as the current flowing from the external circuit during charging increases.
The pulse time width tm' increases as m increases and as the current flowing from the external circuit during discharge increases. Therefore, if the charging and discharging of the capacitor of the multiplier circuit 6 is controlled by the currents 1 and 12 from the increase circuit 13 shown in FIG. The larger the values of 5 and 12 are, the larger it becomes, and the ratio of increase is also determined by adjusting the resistors R8 and R9.
As mentioned above, the currents 1, 12 flowing from the increase circuit 13 into the multiplier circuit 6 increase as the engine cooling water temperature decreases while the starter is being driven, and when the starter is not being driven and the engine speed is at the second set rotation speed. If the number exceeds the specified number or the starter commotion time exceeds the predetermined time, the flow will stop.

Therefore, the pulse time width tm of the pulse signal T2 is such that the starter drive time is within the predetermined time and the engine speed is at the second level.
It becomes significantly larger only when the rotation speed is below the set rotation speed. The pulse signal T outputted from the arithmetic circuit 4, the pulse signal L outputted from the multiplication circuit 6, and the pulse signal circle outputted from the voltage correction circuit 8 are added in time width in an OR circuit 9.

The time width characteristics of the pulse signal T from the OR circuit 9 are shown in FIGS. 3 and 4. Figure 3 shows the engine speed at 10 pm.
The fuel injection time is shown as a function of the cooling water temperature in , and the fuel injection time increases as the cooling water temperature decreases, and in particular, when the starter is being driven, it is significantly longer on the low temperature side than when the starter is not driving. Also, Figure 4 shows
It shows the fuel injection time relative to the engine speed when the engine cooling water temperature is -2 pi 0, and the fuel injection time is constant during cranking if the engine speed is below the first setting. When the rotation speed is between the rotation speed and the second set rotation speed, it decreases in inverse proportion to the rotation speed, and becomes approximately constant above the second set rotation speed. Note that the first set rotation speed (1
The second set rotation speed (28 pm) and second set rotation speed (40 pm) are set corresponding to the initial and complete explosions at the time of starting the internal combustion engine, respectively, so that the transition from the initial combustion engine to the complete explosion is achieved smoothly and the engine is completely activated. Even if the starter drive is continued after a break, plug fogging and engine collapse due to excessive fuel supply are prevented. Although it is possible to start the engine using only the main injector through the above test operation, for example, if the battery voltage decreases and the ignition energy of the plug is low, the engine cannot be started. Therefore, if the star valve continues to be driven, plug fogging will begin to occur due to the increased amount of fuel, but if the star valve is driven for a predetermined time or longer, the fuel will no longer be increased, and the engine will become streaky due to the continued driving of the star valve. Since the air and fuel are evaporated, restarting the engine after a failed engine start is extremely easy. In addition, in the above embodiment, the time limit circuit 1
The time set in step 6 does not necessarily have to be related to the engine temperature, and may be a fixed time.

As is clear from the above-mentioned operation, according to the present invention, ``particularly, an appropriate increase in fuel is performed by the action of the fuel increasing means, and the engine can be started using only the main injector, thereby reducing the cost and increasing the reliability of the device. Furthermore, due to the action of the timer, when the starting time exceeds the set time, the increasing operation is stopped, preventing the spark plug from being covered with fuel, and restarting the engine smoothly. It has a cool effect.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is an electrical wiring diagram showing a part of the detailed configuration of the embodiment shown in FIG. 1, and FIG. 3 is a cooling diagram in this embodiment. FIG. 4 is a characteristic diagram showing the fuel injection time with respect to the water temperature. FIG. 4 is a characteristic diagram showing the fuel injection time with respect to the rotational speed in this embodiment. 4... Arithmetic circuit, 7... Operating state detection means, 1
1...Solenoid injection valve, 13...Increasing circuit, 1
5... Comparison circuit, 16... Time limit circuit. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an electronically controlled fuel injection device that regulates the fuel supply amount using a pulse signal with a time width that corresponds to the operating state of the internal combustion engine, when the engine speed is less than or equal to the first set rotation speed, a calculation means for generating a pulse signal having a constant clock width and, above a first set rotation speed, generating a pulse signal related to the engine rotation speed; increasing means for increasing the time width of the pulse signal obtained by the calculation means at a ratio corresponding to the engine temperature when the rotation speed is below the set rotation speed and the starter is being driven;
When the starter driving time exceeds a set time, a timer means for stopping the amount increasing action by the amount increasing means, and an electromagnetic injection valve installed in the internal combustion engine and injecting fuel in response to a pulse signal with an increase-corrected time width. An electronically controlled fuel injection device, characterized in that fuel is supplied to an internal combustion engine only by the electromagnetic injection valve.