JPS6027818B2 - Electronically controlled fuel injection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device, and particularly to an improved structure for increasing the amount of fuel injection at the time of starting an internal combustion engine (referred to as starting amount increase).

In conventional fuel injection systems for internal combustion engines, in order to improve starting performance when the engine cooling water temperature is low, for example, in addition to the main injection valve, one or more intake pipes are injected at a position away from the engine cylinders to start the engine. An auxiliary injection valve for increasing the number of vehicles is installed, and the injection time of the auxiliary injection valve is set to a roughly constant value, and even if the starter is continued to be turned, after a certain period of time, the auxiliary injection valve for starting is deactivated and ignition is started. It has a thermo-time switch to prevent the plug from covering.

An example of this is shown in FIG. 1, which is attached to the part that senses the cooling water temperature of the engine, and when the starter 200 is turned, the starting auxiliary injection valve 100' is energized and the heating coil 1 is energized.
01 is also energized and when the starter 200 continues to be turned, the bimetal 102 is loosened by the heat generated by the heating coil 101, and its point 103 is opened to open the starting auxiliary injection valve 10.
The power supply to 0 is stopped. Here, the starting auxiliary injection valve 10 is heated until the bimetal 102 is loosened by the heating coil 101 and the point 103 is opened.
The point 103 is set to open when the bimetal 102 is loosened until the energization time reaches 0 and the temperature of the cooling water of the engine reaches or exceeds the temperature (for example, 35q○).
In addition, the heat coil 101 generates more heat as the current increases, and the heat that loosens the bimetal increases.
It is configured such that the energization time varies. However, the structure described above is structurally complex because it includes the starting auxiliary injection valve 100 and the thermo-time switch, and an expensive one is required only when starting the engine.
Furthermore, the fuel piping to the starting auxiliary injection valve 100, the electrical wiring to the thermotime switch, etc. are disadvantageous not only in terms of high costs but also in terms of repair.

Also, at low temperatures, a large amount of fuel remains in the engine's intake pipe, and some of it evaporates and is sucked into each cylinder to start the engine, so some fuel remains even after the engine has started. Since it remains in the intake pipe of the engine and is gradually inhaled after engine startup is complete, it has the disadvantage of deteriorating exhaust gas emissions (particularly HC). Furthermore, since the distribution to each cylinder is poor, there is a problem in that more fuel than necessary for starting is injected, resulting in a slight deterioration in fuel efficiency. Therefore, it has been proposed to eliminate the auxiliary injection valve for starting and start only by increasing the amount of fuel in the main injection valve, but since fuel vaporization is poor especially at low temperatures, it is necessary to keep the air-fuel ratio in the cylinder within the flammable range. Therefore, a larger amount of fuel is required, and the amount of fuel injected from the main injection valve becomes enormous, as can be seen from FIG.

However, when the internal combustion engine reaches its full capacity, the temperature inside the cylinder rises and fuel vaporization improves, and the air-fuel ratio inside the cylinder becomes excessively rich, causing the spark plug to smolder, which is necessary at the beginning of startup as shown in Figure 5. However, if a certain amount of fuel is continuously supplied, the engine stalls. The present invention is configured to detect a change in the operating state of the internal combustion engine caused by a failure of the internal combustion engine while the starter is operating, and to stop increasing the amount of fuel even if the starter is operating when the engine reaches a complete explosion. By doing this, you can start the engine reliably without stalling.
Moreover, it is an object of the present invention to realize an electronically controlled fuel injection device that can be configured without using an auxiliary starting injection valve.

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

In this embodiment, an electronically controlled fuel injection system will be described which performs basic fuel injection in accordance with the engine rotational speed and the intake air amount of the engine. In Fig. 2, 1 is the primary side terminal of the ignition coil for detecting the engine rotation signal as a pulse signal, 2 is a waveform shaping circuit that shapes the pulse signal from terminal 1 to prevent malfunction, and 3 is a separate circuit. In the circular circuit, for example, in the case of a 6-cylinder engine, the main injector 1 injects fuel with one revolution of the engine.
In order to operate the injection valve 11 once, a 1/3 frequency division circuit is used, and if the injection valve 11 is to be operated more than once per engine revolution, a circuit with a different frequency division ratio is required. Needless to say. 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 air amount sensor 5, and calculates a time width Tp obtained by dividing the intake air amount of the engine by the engine rotation speed. A pulse signal T, is generated.

The time width Tp of the pulse signal T is proportional to the amount of air sucked into one cylinder in one stroke. 6 is a multiplication circuit that receives the pulse signal T.6 output from the arithmetic circuit 4. A pulse signal T2 having a pulse time width tm is output by multiplying the pulse time width tp by various signals from the operating state detection means 7 that detects the engine cooling water temperature, intake air amount, etc.

8 is a voltage correction circuit that receives the pulse signal L from the multiplication circuit 6.
is input, and a pulse signal T3 having a pulse time width tn corresponding to the power supply voltage is output in order to correct the change in the fuel injection amount of the main injection valve 11 due to the power supply voltage (for example, the voltage of a storage battery of an automobile).

9 is an OR circuit which receives pulse signals T, , T2, T3 from the arithmetic circuit 4, the multiplication circuit 6, and the voltage correction circuit 8;
is input, and a pulse signal T having a pulse time width (tp+tm+desk) is output to the output circuit 101.

Reference numeral 14 denotes a pressure switch, which is connected to a diaphragm 14a, a spring 14b, a point 14c that opens and closes integrally with the diaphragm 14a, and a negative pressure chamber 14d that is connected to the intake pipe of the engine 15 main body by a negative pressure signal introduction pipe 17. It is configured.

When the intake pipe internal pressure reaches a set value (a value determined by the spring constant of the spring 14b, which is preset to a value at which it is recognized that the engine has reached a complete explosion), the suction force of the negative pressure increases to the spring constant. , the diaphragm 14a moves and the point 14c closes. FIG. 3 shows the change in the negative pressure in the intake pipe at the time of starting when the engine cooling water temperature is -1oo0, and it can be seen that the negative pressure increases rapidly after the start of cranking and after the first explosion. Point 14c of pressure switch 14 is open, and terminal 1
While a signal indicating that the starter is being driven is input to the engine 2, the finger cooling circuit 16 generates a starting increase signal.

The signal is input to the arithmetic circuit 4 and the increase circuit 13,
The increase circuit 13 operates in response to the signal and transmits an amplified signal to the multiplication circuit 6 in order to increase the fuel injection amount in accordance with the engine temperature detected by the operating state detection means 7.
As the arithmetic circuit 4, for example, a multi-pipelator with a variable pulse time width, which is described in Jibatsu No. 49-67016, is used. The charging of the capacitor is controlled by the pulse signal from the frequency dividing circuit 3, and the discharging thereof is controlled by the air amount sensor 5. Then, a pulse signal T, whose time width tp is inversely proportional to the engine rotational speed and proportional to the intake air amount of the engine, is generated. As stated 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 rotational speed of the engine, so by appropriately selecting the circuit constants of the arithmetic circuit 4, the capacitor charging voltage can be adjusted is saturated at low rotation speeds, and the pulse width tp can be kept constant with respect to the rotation speed while the engine does not reach a complete image.
In this way, the time width tp of the pulse signal T, generated by the arithmetic circuit 4 is different from the time width tp of the pulse signal T, which is generated by the arithmetic circuit 4 when the engine is running at low speeds (for example, 12
If the rotation speed is less than 100 pm), it is constant with respect to the rotation speed, and if the rotation speed is higher than that, it is the opposite of the rotation speed. The reason why the pulse signal T is made independent of the rotational speed at low rotational speeds such as when starting the engine is to prevent the amount of fuel injection from becoming too large.

Furthermore, by controlling the discharge of the capacitor of this arithmetic circuit 4 in accordance with not only the signal from the air amount sensor 5 but also the starting amount increase signal from the command circuit 16, the pulse signal T
, can be made larger than the value proportional to the actual amount of air. It is known to generate a pulse signal with a time width proportional to the actual amount of air when starting the engine, and in this embodiment, this is done in response to the starting amount increase signal. An example of a circuit responsible for increasing the starting power is shown in Fig. 4.
FIG. 4 shows the detailed configuration of the operating state detection means 7, the increase circuit 13, and the command circuit 16. As shown, the increase circuit 13
is composed of resistors R4, R5, R6, R7, R8, R9, transistors Tr2, Tr3, and the operating state detection means 7 is composed of a thermistor 70 for water temperature detection, resistors R, o, R,
．． , R, 2, and a transistor Tr4, and the command circuit 16 includes transistors Tr, , resistors R, . R2, R3,
It consists of a capacitor C, and a diode D.
In the operating state detection means 7, since the resistance value of the thermistor 70 increases as the engine cooling water temperature decreases, the resistor R,2 and the transistor Tr connected as an emitter follower
The emitter potential of No. 4 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 Tr
Currents 1 and 12 flow through transistor Tr2 and transistor T, respectively, during star drive. Here, the voltage applied to the emitters of transistors h2 and Tr3 is:
In both cases, the voltage across the resistors R and 2 of the operating state detection means 7 is not the constant power supply voltage V8, so the transistor T
The higher the emitter potential of r4, the larger 1, 12 becomes. That is, the currents 1, 12 become larger as the cooling water temperature becomes lower. However, even when the starter is running, when the intake air pressure increases and the point 14c of the pressure switch 14 closes, the transistor m is forcibly cut off, so the transistors Tr2, T3 are also cut off, and the current 1,...
12 does not flow. Fig. 5 shows the fuel injection time with respect to the cooling water temperature at an engine rotation speed of 10 pm, and the fuel injection time increases as the cooling temperature decreases.
In particular, when the starter is operating, it becomes significantly larger on the low temperature side than when the starter is stopped. Said current 1. ,1
The multiplication circuit 6 to which 2 is input is, for example,
It is configured as a variable time width multipipulator described in Japanese Patent No. 16. This multipipulator is
It has a capacitor that is charged during the pulse time width tp of the pulse signal T from the arithmetic circuit 4, and generates a pulse signal T2 with a pulse time width tm equal to the discharge duration after the completion of charging. The larger the current flowing from the external circuit, the larger the pulse time width tm, and the larger the current flowing from the external circuit during discharge, the larger the pulse time width tm. 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 1 and 12 are, the larger the value becomes, and the increase ratio is also determined by adjusting the resistors R8 and R9. When the internal combustion engine reaches full capacity and the intake pipe internal pressure increases rapidly, closing the contact point of the breather switch 14, even if the starter activation signal continues to be input from terminals 1 to 2 in FIG. 4, it is applied to the transistor Tr. The base potential becomes 0, the increase signals 1, 12 are stopped, and the huge starting increase is stopped.

Therefore, when the engine is fully run and the fuel vaporizes well and becomes rich, even if you continue to turn the starter, the amount of fuel injected will decrease rapidly, preventing the spark plug from fogging up or smoldering. . Furthermore, since basic calculations are being performed based on the signal from the air amount sensor 5 at this time, the engine can be reliably started without stalling. Figure 6 shows the fuel injection pulse width at startup with respect to the negative pressure in the intake pipe of the engine when the engine cooling water temperature is -20°C. (below), it remains constant to prevent excess fuel, and until it reaches the negative pressure (110 Hg) corresponding to complete contact, it decreases in inverse proportion to the negative pressure, and the point 1 of the pressure switch 14
After the opening of 4c (-15 Hg), it becomes approximately constant. In addition to the above-mentioned method for detecting the negative pressure in the intake pipe, methods for detecting the completion of the internal combustion engine at the time of starting the engine include methods for detecting changes in the output of an exhaust temperature sensor installed in the exhaust system, or methods for detecting engine oil pressure. A device that detects changes in the output of a sensor or the like may be used.

As described above, the present invention is equipped with an increase means for increasing the amount of fuel supplied when starting the engine, and is equipped with an increase restriction means that limits the amount of fuel increased by the increase means when the internal combustion engine reaches complete explosion. , it is possible to automatically limit the increase in fuel when the internal combustion engine reaches full speed after starting.
Reliable starting can be achieved, and according to the present invention, starting of the internal combustion engine can be achieved using only the main injection valve, which has the excellent effect of reducing the cost and improving the reliability of the apparatus.

Brief Description of the Drawings Fig. 1 is a schematic diagram showing the configuration of a thermosim switch used in a conventional device, and Fig. 2 is a block diagram showing a part of the overall configuration of an embodiment of the present invention. , FIG. 3 is a characteristic diagram showing the relationship between the progress of startup and the negative pressure in the intake pipe in the embodiment shown in FIG. 2, FIG. 4 is an electrical wiring diagram showing a part of the detailed configuration in FIG. FIG. 6 is a characteristic diagram showing fuel injection time versus cooling water temperature in this embodiment, and FIG. 6 is a characteristic diagram showing fuel injection pulse width versus intake pipe internal pressure in this embodiment.

13... A boosting circuit constituting a boosting means, 14... A pressure switch serving as a detection means, 16... A command circuit serving as a boosting limiting means.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. While the internal combustion engine is operating, a fuel amount is calculated according to its operating state, this fuel amount is increased according to the temperature of the engine, and this increased fuel amount is injected into the engine by a fuel injection valve. an electronically controlled fuel injection device for supplying fuel to the engine, comprising: a starting temperature increase means for making an increase correction according to the temperature of the engine when the starter is operating to be sufficiently larger than the increase correction when the starter is not operating; a complete explosion detection means for detecting a complete explosion of the fuel before the complete explosion occurs, and in response to the detection of a complete explosion of the fuel by the complete explosion detection means, the increase correction by the starting temperature increase means is performed independently of the operation of the starter. 1. An electronically controlled fuel injection device, comprising: an increase limiter for limiting an amount of fuel, and controlling fuel supply by the fuel injection valve at the time of starting the engine.