JPS6047463B2 - fuel injector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection device for an internal combustion engine that measures fuel for a plurality of cylinders using a solenoid valve that operates intermittently in response to a timed pulse voltage.

Conventionally, in a carburetor, fuel for an engine is measured using a fuel nozzle that opens in a ventilate section provided upstream of the throttle valve in the intake pipe. There was a problem with poor accuracy. On the other hand, in a fuel injection system that uses a solenoid valve to intermittently meter fuel in an engine, a solenoid valve is disposed for each cylinder in the intake manifold of the engine, and fuel injection for each cylinder has been performed. However, although this fuel injection system has better fuel metering accuracy than a carburetor, multi-cylinder engines require the same number of solenoid valves as the number of cylinders, which increases costs and causes variations in the flow characteristics of each solenoid valve. There was a problem that caused the air-fuel ratio to vary between cylinders.

Furthermore, the particle size of the fuel injected from the solenoid valve is considerably larger than the spray particle size of the carburetor, which has the disadvantage that very good atomization cannot be obtained. Therefore, it may be possible to reduce the fuel injection particle diameter and improve fuel metering accuracy by using a solenoid valve to meter the fuel to the fuel nozzle that opens in the ventilate section upstream of the throttle valve.

In this case, since fuel metering to multiple cylinders is controlled by one solenoid valve, fuel is metered frequently, for example, every intake stroke of each cylinder of the engine (for a 4-cylinder 7-cycle engine, 4 times per 2 revolutions of the crankshaft). ) This solenoid valve needs to be driven to open and close. For example, when a solenoid valve is driven to open and close in synchronization with engine rotation, if the fuel pressure is pressurized to a constant J value, a large amount of fuel is required, especially when the engine is at high speed and under high load, and the solenoid valve becomes long. Although the valve must be driven to open for a certain period of time, the permissible opening/closing operation time of the solenoid valve becomes shorter, making it impossible to ensure sufficient fuel metering accuracy. Therefore, in the present invention, a fuel nozzle that opens a ventilate section formed upstream of the intake system throttle valve of the engine, and an electromagnetic valve that responds to timed pulses to open and close the fuel nozzle are arranged, and the fuel metering for multiple cylinders is provided. In order to perform this with a single solenoid valve, a timed pulse with a time width corresponding to the operating state of the engine is generated intermittently to drive the solenoid valve, and the fuel pressure to the solenoid valve is applied to the downstream side of the throttle valve. It is an object of the present invention to provide a fuel injection device that can generate good spray while ensuring reliable operation of a solenoid valve by controlling according to intake pipe pressure.

The present invention will be described in detail below with reference to embodiments shown in the drawings. FIG. 1 is a diagram illustrating the configuration of main parts in an embodiment of the present invention, where 2 is an air filter provided upstream of an intake pipe 4 of a multi-cylinder engine 1 to purify intake air, and 3 is an air filter 4 of an intake pipe 4.
A throttle valve installed downstream of the air filter 2 adjusts the flow rate of intake air.

Reference numeral 41 denotes an intake manifold downstream of the intake pipe 4, and intake air is drawn into each cylinder through the intake manifold 41 every intake stroke.

The throttle valve 3 is operated in conjunction with the accelerator. 5 is a fuel tank, and 6 is a fuel pump that supplies fuel under pressure.

7 is a solenoid valve for intermittent supply of fuel, and 8 is a fuel pressure regulator for adjusting the pressure of fuel pressurized by a fuel pump.

In this embodiment, the pressure regulator 8 is formed with a negative pressure chamber 82 and a fuel chamber 83, which are partitioned by a diaphragm 81, and the negative pressure chamber 82 includes a spring 84 that applies an initial load to the diaphragm 81 (that is, fuel). Further, the intake negative pressure downstream of the throttle valve 3 of the intake pipe 4 is introduced into the negative pressure chamber, and a portion of the pressurized fuel from the fuel pump 6 is introduced into the fuel chamber 83. It has been introduced. The pressure regulator 8 is connected to the diaphragm 81 and is integrated with the diaphragm 81!
The fuel pressure is adjusted by returning the fuel in the fuel chamber 83 to the fuel tank by the displacing valve 85, so that the fuel pressure is adjusted to a value corresponding to the intake negative pressure. Reference numeral 10 denotes a crank angle detector for detecting the rotation angle of the crank. In this embodiment, an inductor 10a is arranged on the crankshaft 1a of a multi-cylinder engine 1, and an electromagnetic pickup 10b is arranged opposite to it. using things.

Reference numeral 9 denotes a pressure detector installed in the intake pipe 4 downstream of the throttle valve 3, which detects the intake negative pressure. In this embodiment, a semiconductor strain gauge is used, and the intake pressure P1 ( Generates an intake pressure voltage ■P proportional to the absolute pressure).

Reference numeral 11 denotes an electrical control circuit that examines the operating conditions of the engine 1 based on these detection signals, generates a timed pulse in accordance with a pre-planned air-fuel ratio, and determines the opening time of the electromagnetic valve 7.
For example, in a 4-cylinder, 4-cycle engine, the crank angle detector 10 generates a positive pulse voltage every 114 revolutions of the engine, and the crank angle detector 10 is configured to detect the integral period of a double integral timed pulse generator included in the electrical control circuit 11 and Determine the rise timing of the timed pulse. The solenoid valve 7 is connected to the inner ventilate 14'' of a double ventilator section 14 disposed upstream of the throttle valve 3.
The fuel nozzle 14" is arranged to inject fuel into the 7 fuel nozzle 14" which opens at The configuration is determined by the regulator 8, and
The outlet side pressure P8 leading to the fuel nozzle 14'' is approximately equal to atmospheric pressure. Therefore, within the range where the response delay of the solenoid valve 7 can be ignored, the amount of fuel passing through one operation QF = k''1k
″″P1+PO−PBτ. Here, PO is the pressure due to the set load of the spring 84 of the pressure regulator 8, and P! P8 is the pressure on the downstream side of the target valve 3, and P8 is the pressure on the nozzle 14'' side, both of which are expressed as absolute pressures. τ is the opening time of the solenoid valve 7, and k'' and k'''' are constants. Moreover, the electrical control circuit 1
No. 1 generates a timed pulse train for metering fuel for a plurality of cylinders using one electromagnetic valve, and performs fuel injection an equal number of times with respect to the operation frequency of all intake strokes of the corresponding cylinders.

That is, when fuel metering for all cylinders is performed by one solenoid valve 7 in a multi-cylinder four-stroke engine, the frequency of operation of the intake stroke for all cylinders is two LI times per crankshaft rotation. Here, L is the number of cylinders that one solenoid valve should handle. Therefore, the operating frequency F of the solenoid valve is (LI2)·I per crankshaft rotation. I is the number of actuations of the solenoid valve per one suction stroke, and 1 is an integer that is the minimum value. For example, if we consider the case where a 4-cylinder 4-stroke engine is metered with one solenoid valve, the minimum number of times the solenoid valve operates per crankshaft rotation is L = 4 and I = 1, so F = (412) x 1 =
There are 2.

The electrical control circuit 11 generates a timed pulse for each angle signal generated by the crank angle detector 10, and determines the opening time of the solenoid valve 7.
The range over which the activation delay is ignored is equal to the time width of the applied timed pulse.

In addition, in the case of an Otto engine, the weight ratio between the amount of intake air and the amount of fuel (
Good efficiency and exhaust performance cannot be obtained unless the air-fuel ratio (M) is an appropriate value. The amount of air QA taken in each intake stroke of the engine 1 is determined by the intake pressure P on the downstream side of the throttle valve, and QA=k''''P, where k is a constant.

Therefore, it is necessary to control the valve opening time width τ in each operation of the solenoid valve 7 to realize a mixture with an appropriate air-fuel ratio. As mentioned above, the amount of intake air Q9 for each intake stroke of the engine is QA=
k″″″P, and the injection amount QF in one operation of the solenoid valve is QF=k″Vk″″P1+PO−PBτ, and Q
A/QF=M, where M is the air-fuel ratio and τ is the solenoid valve opening time k'', k'', k'''' are constants. Solving these relational expressions for τ gives the following equation.

As long as the response delay of the electromagnetic valve 7 is negligible, equation (1) determines the time width of the timed pulse for driving the electromagnetic valve 7. Therefore, based on equation (1), electric control circuit 1 for generating a timed pulse that determines the opening time of the solenoid valve.
An example of the circuit configuration of No. 1 is shown in FIG.

Here, 9 is the intake pipe pressure Pz on the downstream side of the engine throttle valve.
There is an intake pressure detector for generating an intake pressure Vp proportional to . 21 has the first divider, v? Calculate and output.

22 is constant setting A constant voltage V1 is generated.

23 is an adder, and a calculation output of the divider 21 and a constant setter? 2■ Add the output voltages of ±22 and output ■1+, 7, ■.

24 is the second divider, Calculate and output Vp/(V, +! 4 red).

25 is a square root calculator; Calculate.

Reference numeral 27 denotes an air-fuel ratio function generator, which detects operating conditions from an engine operating condition detector and generates a voltage corresponding to a pre-planned air-fuel ratio M. In this embodiment, the rotational pulse voltage of the crank angle detector 10, which generates a pulse voltage at every fixed rotational angle of the crankshaft 1a of the engine, is converted to a rotational speed voltage proportional to the engine rotational speed by the frequency-voltage converter 26. At the same time, the engine cooling water temperature t is converted into a water temperature voltage Vt corresponding to the cooling water temperature t by a water temperature detector 15 using, for example, a thermistor, and the oxygen in the exhaust gas installed in the engine exhaust pipe is converted. Oxygen concentration detector 1 that detects concentration
2, the air-fuel ratio voltage Vλ having Z characteristics near the ring mixture ratio
An example of this is an oxygen concentration detector 12 made of zirconia or the like as a base material. Based on these detection signals, the air-fuel ratio function voltage generator 27 generates an air-fuel ratio voltage M corresponding to the planned value of the air-fuel ratio M. Then, the output voltage of the square root calculator 25 and the air-fuel ratio function voltage generator 27 The generated air-fuel ratio voltage ■9 is led to the divider 28, and is calculated.

This value expresses the valve opening time width τ shown in equation (1) in the form of voltage, and is referred to as the fuel control voltage ■C. Therefore, a voltage-controlled time pulse generator 29 converts the voltage value of equation (2) into a time pulse width. This timed pulse generator 29 is triggered by the rotation pulse voltage of the rotation angle detector 10 and generates five timed pulses, but the time width T of the timed pulse is the control voltage Vc applied for pulse width control.
It has the function defined by the control voltage ■C
By applying the voltage calculated by the formula (2) generated by the third divider 28, the timed pulse calculated by the formula (1) can be generated at a frequency equal to the operating frequency of the engine's suction stroke. can. Note that the divider 21 in this embodiment
, 24 and 28 are Model 4450 manufactured by Teledyne Film Corporation, USA.

As the square root calculator 25, model 4353, also manufactured by Teledyne Film Corporation, is used. Further, as an example of the voltage controlled time pulse generator 29, an electrical wiring diagram is shown in FIG. In this figure, 10 is a crankshaft rotation angle detector, and an inductor 10a that is engaged with the engine crankshaft.
An electromagnetic pickup 10b facing the pump generates a pulse voltage rotation angle signal every suction stroke. This rotation angle signal is shaped by a waveform shaping circuit 30, and inverters 31 and 32 generate timing pulses with opposite polarities.
These timing pulses are integrated voltage 36 of integrator 33.
The operational amplifier 37 generates a sawtooth wave voltage in synchronization with the rotation angle signal. This sawtooth wave voltage is compared by comparators 38 and 39 and converted into a pulse voltage.
is used, a pulse voltage with a time width corresponding to this voltage Vc is generated, and after inverting the polarity of this voltage with an inverter 40, it is passed through the output of the comparator 38 and an AND gate 41 to generate a pulse voltage proportional to the fuel control voltage Vc. A timed pulse with a time width T is obtained. By applying the timed pulse thus calculated to the excitation coil of the solenoid valve 7 and driving it, the fuel metered by the solenoid valve 7 can satisfy a predetermined air-fuel ratio, and this fuel is injected through the fuel nozzle 14'' to the small vent 1'' of the vent 14. Here, when the opening degree of the throttle valve 3 is small and the intake pressure P! is small, the pressure on the fuel inlet side of the solenoid valve 7 is Since the PF is also small, the injection pressure is low, and large droplets are ejected from the fuel nozzle 14'', but because the differential pressure across the throttle valve 3 is large, the spray becomes sufficiently fine in particle size when passing through the throttle valve. Good combustion can be achieved as it is sucked into the engine.

5. Also, when the opening of the throttle valve 3 is large, such as when the engine is in a high-speed/high-load state, the intake pressure P increases, so the pressure PF on the fuel inlet side of the solenoid valve 7 also increases, and the injection pressure increases, resulting in spraying. As the particle size becomes smaller and the air flow velocity in the ventilate section 14 also increases, the fuel coming out of the nozzle 14'' is sufficiently atomized and becomes a good air-fuel mixture.In this way, the opening degree of the throttle valve 3 becomes large, and the downstream When the intake pressure P, increases, the fuel pressure PF to the solenoid valve 7 also increases, so the opening time τ of the solenoid valve 7 per time can be shortened, and the high-speed rotation of the engine Even if the permissible opening time of the solenoid valve 7 becomes shorter, the amount of fuel required by the internal combustion engine can be secured.

Further, in the embodiment of the fuel system shown in FIG. 1, the intake pressure P1 (for example, manifold pressure) on the downstream side of the throttle valve of the engine is detected as the engine operating condition detector, and the solenoid valve 7
The inlet side fuel pressure is the intake air pressure P! The fuel metering method is shown in which the amount of intake air per unit time Qa is detected as an engine operating condition detector using, for example, a Jayama style air flow meter inserted in the intake duct, and the engine speed is Of course, the present invention is also applicable to a method in which Qa/N is calculated for N, the amount of intake air in each intake stroke is detected, and fuel is measured.

In this case, the equation giving the valve opening time γ of the electromagnetic valve corresponding to the above-mentioned equation (1) is as follows.

Furthermore, considering the special case of PO=PB, this means that the set pressure of the spring 84 of the fuel pressure regulator 8 is 1 in absolute value.
This is the case where the atmospheric pressure is set, and what happens when the negative chamber 82 is opened to the atmosphere? The pressure setting value is 2 atmospheres in absolute pressure and 1 atmosphere in relative pressure.
becomes atmospheric pressure.

(However, the atmospheric pressure is 1 atm.) Equation (1) and (1″)
Is γ equal to τ? GY=? P?・・・・・・・・・(3)
Therefore, the configuration of the electrical control circuit for calculating the timed pulse can be simplified as shown in another embodiment of FIG. Since the same reference numerals in this other embodiment have the same structure as the embodiment shown in FIG. 2, a description thereof will be omitted. In addition, as shown in still another embodiment of FIG. 5, an air bleed 14a is provided for the fuel nozzle 14'' of the ventilate section 14, and the particle size of the fuel spray is controlled by mixing the fuel and bleed air. It is also possible to make it more detailed.

7 is an electromagnetic valve, 14'' is a small ventilary, and the other configurations are the same as those in the embodiment shown in FIG. The structure is such that the fuel metered intermittently by a solenoid valve is injected from a fuel nozzle that opens into this ventilate, and the fuel pressure to the solenoid valve is controlled in accordance with the intake pressure downstream of the throttle valve. This makes it possible to measure fuel equally for all intake strokes with a single solenoid valve for a multi-cylinder engine, and to ensure accurate fuel spray with small spray droplet size under various operating conditions. It has the excellent effect of being done well and reliably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a block diagram of the electrical control circuit shown in FIG. 1, and FIG. 3 is a voltage-controlled timer shown in FIG. 2. FIG. 4 is a block diagram showing another embodiment of the electrical control circuit, and FIG. 5 is a cross-sectional view showing another embodiment of the ventilator.

3... Throttle valve, 4... Intake pipe,
7...Solenoid valve, 11...Electrical control circuit, 14...Pliers" yuri part, 14"...
...Fuel nozzle.

Claims (1)

[Claims] 1. A ventilary section disposed upstream of a throttle valve that adjusts the amount of intake air in an intake pipe of a multi-cylinder internal combustion engine, a fuel nozzle that opens into the ventilary section, and a device for intermittent pressurized fuel injected from the fuel nozzle. a solenoid valve disposed to open and close in response to a timed pulse; a fuel pressure regulator that controls the fuel pressure of pressurized fuel supplied to the solenoid valve in accordance with intake pipe pressure downstream of the throttle valve; A fuel injection device comprising: an electric control circuit that intermittently generates a timed pulse to open a solenoid valve and controls the duration of the pulse in accordance with engine operating conditions.