JPS62135638A - Fuel injection device for engine - Google Patents

Abstract

PURPOSE:To make uniform a fuel distribution with respect to a suction air and promote vaporization and atomization of fuel, by correcting a fuel injection pulse period upon determination of an engine cold condition to a value smaller than a pulse period under an engine warm condition. CONSTITUTION:A rotation detecting means 5 receives a signal from a crank angle sensor 4 to detect an engine rotation, and a suction air quantity detecting means 7 receives a signal from an air flow sensor 6 to detect a suction air quantity. An injection pulse control means 8 receives signals from both the detecting means 5 and 7 to obtain a fuel injection pulse and output the same to a fuel injection valve 3. A cold condition determining means 10 is provided to determine an engine cold condition according to a signal from a water temperature sensor 9. A period correcting means 11 is provided to output to the control means 8 a pulse period correction signal for correcting a pulse period under an engine cold condition to a value smaller than that under an engine warm condition upon determination of the engine cold condition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a fuel injection device for an engine.

(Prior art) In general, in an engine fuel injection device, in order to supply fuel injection j determined according to the operating state of the engine, the fuel injection device only performs injection for a predetermined injection time determined according to the injection capacity of the fuel injection valve. The injection pulse is output to the fuel injection valve. Also, at high loads with large injection pulses,
Techniques are also known in which the pulse period is shortened and the injection is divided into multiple times (for example, Japanese Patent Laid-Open No. 58-570
(See No. 34).

However, under different conditions of the engine, in addition to the fact that the vaporization and atomization of the fuel are already low, if the fuel that has been used for warming up is injected at one time due to the small amount of intake air, one cycle All the fuel will be injected within a short period of time. Therefore, the distribution of fuel with respect to the intake air becomes large (one occurs) and becomes uneven, resulting in fuel vaporization,
Mixing with air is insufficient due to promotion of atomization.

Furthermore, as the fuel supply t is increased in order to improve combustibility, fuel efficiency deteriorates.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention has been developed to inject fuel 1/1 with an injection pulse according to the intake air ω at a period synchronized with the rotation of the engine, by vaporizing the fuel in a cold state, An object of the present invention is to provide a fuel injection device for an engine that promotes atomization.

(Structure of the Invention) The fuel injection device of the present invention obtains a fuel injection pulse corresponding to an injection amount according to an intake air amount and outputs it to a fuel injection valve at a period synchronized with engine rotation. In addition to providing a means for determining the state of the cold machine, a means for determining the state of the cold machine is provided. The apparatus is characterized in that a period correction means is provided for correcting the pulse period in the cold state to a value smaller than the pulse period in the warm state in accordance with the signal from the determination means.

FIG. 1 is a diagram showing the entire structure of the present invention.

The fuel injection valve 3 installed in the intake passage 2 of the engine 1 injects and supplies fuel, and the rotation of the engine 1 is detected by the rotation detecting means 5 based on the signal of the crank angle sensor 4, for example, and the intake air is The intake air amount is detected by the intake air amount detection means 7 based on the signal from the air flow sensor 6, for example. The injection Q'J pulse control means 8 receives the signals from the rotation detecting means 5 and the intake air amount detecting means 7, and generates a fuel II injection pulse corresponding to the injection amount according to the intake air amount at a period synchronized with the rotation of the engine. This is determined and output to the fuel injection valve 3 at a predetermined time to inject and supply fuel.

A cold state determining means 10 is provided for detecting and determining the cold state of the engine 1 based on, for example, a signal from a water temperature sensor 9 that detects the cooling water temperature. , a pulse period correction signal for correcting the pulse period in the cold state to be smaller than the pulse period in the warm state is output to the injection pulse control means 8, thereby increasing the number of injections in the cold state.

(Effects of the Invention) According to the present invention, by correcting the pulse period of fuel injection to a small value when the engine is in a cold state and injecting and supplying the amount of fuel necessary for one combustion in multiple times, In addition to equalizing the distribution of fuel to intake air,
By applying the fuel little by little to the wall surface of the intake passage, it is possible to promote atomization of the fuel, that is, vaporization and atomization, and stable combustibility can be obtained. Therefore, by improving combustibility, it is possible to effectively supply fuel and improve fuel efficiency.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 2 is an overall configuration diagram of a specific example of an engine equipped with a fuel injection device.

The engine 1 has a combustion port 13 formed above the screws 1 to 12 of each cylinder, an intake boat 15 that is opened and closed by an intake valve 14, and an exhaust port 17 that is opened and closed by an exhaust valve 16.
is opened. An intake passage 2 for supplying intake air is connected to the intake port 15, and an exhaust passage 19 for discharging exhaust gas is connected to the exhaust port 17. Further, an ignition plug 20 is arranged facing the combustion chamber 13.

An air cleaner 21, an air flow sensor 6 for detecting the amount of intake air, and a throttle valve 23 for controlling the amount of intake air are installed in the intake passage 2 from the upstream side.

A fuel injection valve 3 is provided near the intake port 15 of the intake passage 2 to inject and supply fuel to the intake passage 2 of each cylinder.

A fuel supply passage 28 is connected to the fuel injection valve 3, through which fuel is supplied from the fuel tank 25 by a fuel pump 26 via a filter 27, and the fuel DI 411)
The fuel that was not checked by J valve 3 is transferred to fuel tank 2.
Two return passages returning to No. 5 are connected. A pressure τ7 regulator 30 is interposed in the return passage 29 so that the pressure of the fuel injected from the fuel injection valve 3 always has a constant differential pressure with respect to the pressure in the intake passage 2 downstream of the throttle valve 23. The return flow■ is adjusted.

Roughly speaking, an air bleed passage 31 is connected and opened to the nozzle part of the fuel injection valve 3, and this air bleed passage 3
The upstream end of 1 is connected to the intake passage 2 upstream of the throttle valve 23, and supplies air according to the pressure difference before and after the throttle valve 23 to atomize the injected fuel.

The pulse period and pulse width of the fuel injection pulse in the fuel injection from the fuel injection valve 3 are controlled by i, II 1ftl signals from the control unit 32 according to the operating state of the engine. The control unit 32 detects the intake air signal from the air flow sensor 6, the throttle opening signal from the throttle sensor 33 that detects the opening of the throttle valve 23, and the engine rotation in order to detect the operating state of the engine. In order to The air-fuel ratio signal from the 02 sensor 37 and the like are respectively input.

The control unit 32 has the functions of each means shown in FIG. 1, determines the fuel injection amount according to the intake air M and the engine speed, and corrects this according to the cooling water temperature and the 02 sensor output. In addition to determining the basic injection pulse during light load and warm-up operation, the fuel injection valve 3 is operated at a cycle synchronized with the rotation of the engine so that the pulse cycle of fuel injection is reduced and multiple injections are performed in one cycle during light loads and warm-up operations. It outputs fuel injection pulses for the

The control unit 32 includes a basic injection pulse determining circuit 38, three frequency dividing circuits, and a frequency dividing rate determining circuit 40, as illustrated in FIG.

The basic injection pulse determining circuit 38 gates the pulse inputted from the crank angle sensor 4 and output as the crankshaft 34 rotates using a signal having a pulse width corresponding to the intake air intake from the near flow sensor 6. At the same time,
A basic injection pulse is obtained by correcting the water temperature signal from the water temperature sensor 9 and the air-fuel ratio signal from the 02 sensor 37, and outputs it to the frequency dividing circuit 39.

On the other hand, the frequency division ratio determination circuit 40 determines the injection region (warm state) as shown in FIG. In the higher load region (■) than A, the frequency division ratio command signal is for single injection with a frequency division ratio of 1, and in the light load region (■) excluding the deceleration region (■), the frequency division ratio command signal is for pre-injection with a frequency division ratio of 2. In the deceleration region (2), a frequency division ratio command signal for fuel cut with a frequency division ratio of O is outputted to each of the three frequency division circuits. Furthermore, the frequency division rate determination circuit 40 divides the frequency division rate command signal for pre-injection with a frequency division rate of 4 during warm-up operation when the engine is cold and the cooling water temperature is lower than the set value, according to the cooling water temperature. It is output to the circuit 39.

The frequency dividing circuit 39 is connected to the basic injection pulse determining circuit 38.
The basic injection pulse is divided by the frequency division rate of the frequency division rate command signal from the frequency division rate determination circuit 40, and an injection pulse having a predetermined pulse width is outputted to the fuel injection valve 3 at a predetermined pulse period. This system injects and supplies fuel.

Meanwhile, FIG. 5 shows the injection timing of the H pulse for a four-cylinder engine. First, FIG. 1, which is the frequency of the basic injection pulse divided by this frequency division ratio.
An injection pulse having a large pulse period and a large pulse width T1 is outputted to the fuel injection valve 3 of each cylinder once per cycle, and injection is performed during the open period of the intake valve 14 of each cylinder by matching the timing between the intake valves 14 of each cylinder. It is something that will be completed.

In addition, Fig. 5B shows injection at J'3 in the light load region ■, the frequency division ratio of the frequency division ratio command signal is 2, and the basic injection pulse is divided by this frequency division ratio to 11t cycles. 2 at equal intervals
A pulse having a small pulse period and a small pulse width T2 is output to the fuel ↑) 10OQ4 valve 3 of each cylinder, and the fuel is supplied twice: at a time that matches the timing between the intake valves 14 of each cylinder and at an intermediate time. This is an injection supply system.

Furthermore, Fig. 5C shows injection during warm-up operation in a cold engine state, and the frequency division ratio of the sprout distribution frequency command signal is 4, and the basic injection pulse is divided into one cycle by this frequency division ratio. A pulse having a roughly small pulse period and an even smaller pulse width T3 is outputted to the fuel injection valve 3 of each cylinder four times at equal intervals, and the pulse is output to the fuel injection valve 3 of each cylinder at a time that coincides with the opening timing of the intake valve 14 of each cylinder and 3 times in between. This system injects and supplies fuel.

The frequency dividing circuit 39 outputs an injection pulse to the fuel injection valve 3 when the effective injection time Te is the injection pulse width corresponding to the fuel injection (2) according to the operating state from the basic injection pulse determination circuit 38. The actual injection pulse width Tt, T2 is calculated by dividing the frequency in consideration of the invalid injection time TV until the actual fuel injection starts.

T3 is set as follows.

T+ =Te +Tv T2 = (Te/2) 10TVT3 = (T
e/4) +Tv According to the above embodiment, in the light load region and during warm-up operation, the pulse period of the injection pulse is made small to perform multiple injections of two or four times in one cycle, thereby improving the fuel distribution. This aims to improve uniformity and atomization. Further, by dividing the fuel into multiple injections, variations in the amount of fuel supplied per cycle are reduced. Roughly, by irradiating Il# little by little several times, the fuel adhering to the wall surface will be vaporized or separated from the wall surface more easily, and fuel can be effectively supplied and fuel efficiency can be improved.

On the other hand, when the load is high, the system switches to single injection due to the capacity and reliability of the fuel injector, and by injecting fuel in accordance with the intake stroke of each cylinder, the injected fuel immediately reaches the combustion chamber. We are trying to have an influx of people. The pulse period switching condition may be determined from the throttle valve opening degree and the engine rotation speed, or may also use a signal corresponding to a load such as intake pressure or injection pulse width.

In the above embodiment, the pulse period of the fuel injection pulse at light load is set to half that of high load, so that injection is performed twice in one cycle, but the pulse period can be further reduced. Multiple injections may be made. In that case, as the number of injections increases, the fuel injection amount per injection, that is, the injection time, becomes shorter and the fuel supply accuracy decreases, so the pulse period is determined by considering the injection accuracy of the fuel injection valve 3, etc. . On the other hand, during warm-up operation, the injection pulse width becomes longer due to the increase in fuel, so good injection accuracy can be obtained even if the pulse period is set to 1/4 as described above. The pulse period of the state is 1
The pulse period may be set to be even smaller than /2 or 1/4.

Furthermore, in the embodiment described above, fuel injection is performed independently in each cylinder at a predetermined timing for the intake stroke of each cylinder. Fuel injection may be performed at the same time.

Furthermore, when reducing the pulse period of fuel injection, by changing the frequency division ratio as described above, in addition to setting the injection timing at equal intervals, it is also possible to divide the injection into multiple times within the period of the intake stroke. The pulse period may be made shorter. At this time, the fuel injection timing and the air supply timing through the air bleed passage 21 match, and a good atomization effect can be obtained.

On the other hand, in the above embodiment, the fuel cut in the deceleration region is obtained by setting the frequency division ratio to O, but when determining the basic injection pulse, the basic injection pulse is not output in the deceleration region. It is a good thing.

Furthermore, in the embodiment described above, the period of the injection pulse is changed using the frequency dividing circuit and the frequency dividing ratio determining circuit.
This pulse period variable means is not limited to this. Furthermore, a microcomputer may be used as the fuel injection control means for digital control II.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention, FIG. 2 is an overall configuration diagram of a specific example of an engine equipped with a fuel injection device according to an embodiment of the present invention, and FIG. Figure 4 is a block diagram of the control unit, Figure 4 is a characteristic diagram showing the injection range corresponding to operating conditions, Figure 5 △, B, and C are graphs of a 4-cylinder engine during high load, light load, and warm-up operation, respectively. FIG. 3 is a characteristic diagram showing the injection pulse period with respect to the intake valve opening timing. 1...Engine 2...Intake passage 3...Fuel injection valve 4...Crank angle sensor 5...Rotation detection means 6... ...Air flow sensor 7...
... Intake mother detection means 8 ... Injection pulse control means 9 ... Water 7FjA sensor 10 ... Cold machine state determination means 11 ... Period correction means 13. ... Combustion chamber 14 ... Intake valve 15 ...
・Intake port 25...Fuel tank 26・
...Fuel pump 28...Fuel supply passage
29... Return passage 30... Pressure regulator 31... Air bleed passage 32... Controller 1-roll unit 33...
... Throttle sensor 38 ... Basic injection pulse determination circuit 39 ...
... Frequency divider circuit 40 ... Frequency division ratio determination circuit Fig. 2 m''3 Fig. 1'' x 4

Claims (1)

[Claims] (1) A fuel injection valve that injects fuel into the engine, a rotation detection means for detecting the rotation of the engine, an intake air amount detection means for detecting the amount of intake air, and a signal from the rotation detection means and the intake air amount detection means. and an injection pulse control means for determining a fuel injection pulse corresponding to an injection amount according to an intake air amount and outputting it to a fuel injection valve at a period synchronized with the rotation of the engine. A cold machine state determining means is provided for determining the cold state of the machine, and a period correcting means is provided for correcting the pulse period in the cold state to a value smaller than the pulse period in the warm state in response to a signal from the cold machine state determining means. Features the engine's fuel injection system.