JPS6138336B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention measures fuel intermittently using a solenoid valve that responds to timed pulses, and supplies fuel that is injected from a vent lily section disposed upstream of an engine's intake system throttle valve. The present invention relates to an injection device, and particularly relates to an injection device with improved atomization characteristics of fuel to be injected and supplied.

In a device such as the one shown in Japanese Utility Model Publication No. 52-21404, in which fuel regulated by a solenoid valve is ejected from a fuel nozzle installed in a bench lily upstream of a throttle valve, the flow rate of air taken into the engine is In operating conditions where the fuel is large, sufficient negative pressure is generated in the ventilator, so that the fuel is sufficiently atomized and a good air-fuel mixture is obtained. However, in operating conditions where the amount of intake air is relatively small, the negative pressure at the vent is also low and the atomization of the fuel is insufficient, resulting in the problem that a uniform air-fuel mixture cannot be obtained.

Therefore, in the present invention, a fuel heater using a PTC element is interposed in the passage leading from the solenoid valve to the fuel nozzle in the bench lily. The purpose is to heat and vaporize the subsequent fuel, smooth the pulsation of the flow caused by intermittent supply, and eject it from the fuel nozzle to obtain a uniform air-fuel mixture. PTC elements have a Curie temperature that depends on the material properties, and have a low resistance value below the Curie temperature, but exhibit a characteristic that the resistance value increases rapidly when the Curie temperature is exceeded, so when used for fuel heating. Unlike nichrome wire heaters, it is possible to stably vaporize fuel with a simple structure, as there is no risk of carbonization or ignition due to overheating.

The present invention will be described in detail below with reference to embodiments shown in the drawings. FIG. 1 is a diagram showing the configuration of this device. Air taken in from the air filter 2 of the engine 1 passes through the intake system's bench lily section 4, has its flow rate adjusted by the throttle valve 3, and is taken in through the intake manifold 16. Ru. Fuel is pressurized from a fuel tank 5 by a fuel pump 6, pressure regulated by a fuel pressure regulator 8, applied to a solenoid valve 7, and metered intermittently according to the valve opening time width. The fuel metered by the solenoid valve 7 passes through the PTC heater 15 using a PTC element and is ejected from the fuel nozzle 44 opening into the small bench 43 of the bench lily part 4, depending on the crank operating conditions of the engine 1. The rotation angle of the shaft is detected by the rotation angle detector 10, and the pressure of the intake manifold 16 is detected by the intake pressure sensor 9, and is guided to the electrical control circuit 11, which calculates the fuel supply amount. , a timed pulse is generated and applied to the solenoid valve 7 to satisfy a pre-planned fuel plan value. Ignoring the slight response delay time, the solenoid valve 7 basically remains open for a period equal to the time width of the timed pulse applied as the driving force, so that the solenoid valve 7 can supply power to the engine with one metering operation of the solenoid valve. The amount of fuel is determined by the time width of the timed pulse, that is, the timed pulse width.

The exhaust system is equipped with a fuel heater that utilizes exhaust heat. That is, the heating plate 13 is disposed at the bottom of the intake manifold 16, the lower surface of the heating plate 13 is in contact with the exhaust gas, and the heating plate 13 is heated to a high temperature when the engine is warmed up. Therefore, droplets of relatively large particle size among the fuel ejected from the fuel nozzle 44 adhere to the upper surface of the heating plate 13, and the temperature of the heating plate, which is vaporized by the heat of the heating plate 13, is controlled by a heat-sensitive drive such as a bimetal. By changing the angle of the jammer cup 14 installed in the exhaust pipe by a means, the exhaust flow rate hitting the lower surface of the heating plate 13 is adjusted, and the heating plate 1
The temperature of No. 3 is controlled to a temperature suitable for heating the fuel.

If the engine is not sufficiently warmed up after being started, the temperature of the heating plate 13 will be relatively low and the ability to vaporize fuel droplets on the top surface of the heating plate will be small. By supplying electricity, electric heat is generated, and the fuel metered by the solenoid valve 7 can be vaporized and ejected from the fuel nozzle 44. When the warm-up of the engine is completed, the heating plate 13 can vaporize the fuel droplets due to the exhaust heat, so the fuel heating function by the PTC heater 15 is no longer necessary. Therefore, the fuel heating function by the PTC heater 15 becomes unnecessary. Therefore, PTC heater 1
Power can also be saved by cutting off the power supply circuit No. 5. An example of the power supply control circuit 11a for this PTC heater 15 is shown in FIG. 2a.

In FIG. 2a, 31 is a battery, 32 is a key switch, and 33 is an engine cooling water temperature discriminator. A thermistor is used as the water temperature sensor 18, and a temperature comparison circuit 33 generates a determination signal that warm-up is insufficient when the cooling water temperature is below a set temperature. and key switch 3 when starting the engine.
2 is detected, and the contact of the relay 36 of the power supply circuit of the PTC heater 15 is closed by the OR signal of the timer circuit 34 which generates a determination signal indicating insufficient warming up for a certain period of time after the starting operation.

Power control circuit 11 for PTC heater 15
As another example of a, as shown in Fig. 2b, a bimetal that detects the temperature near the heating plate 13 opens and closes the contacts, and the power circuit to the PTC heater 15 is opened and closed, which prevents the engine from warming up insufficiently. PTC only during
While the fuel is vaporized by the heater 15, the power supply to the PTC heater 15 can be stopped after warming up.

In this figure, the same numbers refer to figures 1 and 2a.
It has the same configuration as the figure, and numeral 37 is a bimetal disposed to control the temperature control diaphragm plate 14 of the heating plate 13, and a switch 38 engaged with the rotating shaft of the diaphragm plate 14 switches the PTC at a temperature below the set temperature. The power supply circuit of the heater 15 is closed and opened when the temperature is higher than the set temperature.

A timed pulse for driving the electromagnetic valve is generated by an electrical control circuit 11 using a rotation angle detection signal from a rotation angle detector 10 and a pressure detector 9 of the intake manifold as main control parameters. In this embodiment, the control circuit 11 operates the solenoid valve with the same number of metering operations as the number of intake stroke operations of each cylinder of the engine in a relatively low engine speed range where the engine speed is below the set rotation speed.
The fuel is metered in synchronization with the engine crankshaft, and in a relatively high rotation range above the set rotation speed, the solenoid valve is operated at a constant repetition cycle independent of the engine speed to keep the metering frequency constant, and the solenoid valve is opened at a constant frequency. This method performs fuel metering by changing the valve time width.

The configuration diagram of the electrical control circuit 11 of the above method is shown in the third diagram.
As shown in the figure. In FIG. 3, reference numeral 101 is a rotation angle sensor for the engine crankshaft, which generates a rotation angle pulse signal every time the engine takes a suction stroke. A rotation speed voltage generator 102 generates a voltage corresponding to the repetition frequency of the rotation angle pulse signal, that is, a rotation speed voltage _VN . An engine intake pipe pressure detector 103 detects the intake pipe pressure P _I downstream of the throttle valve using, for example, a diffusion type semiconductor pressure gauge, and generates an intake pipe pressure voltage Vp. 104 is a synchronous timed pulse generator, and the repetition period of the timed pulses generated by this is equal to the operation period T _I of the intake stroke of the corresponding cylinder. This timed pulse is called a synchronous timed pulse because it is generated in synchronization with the engine's crankshaft. The time width τ ₁ of the synchronized timed pulse is basically proportional to the amount of air sucked in each intake stroke, so it is proportional to the intake voltage Vp. Reference numeral 105 denotes a timed pulse generator that repeats at a constant cycle and is not synchronized with the rotation angle of the crankshaft of the engine. The asynchronous timed pulse generated here has a constant repetition frequency that is unrelated to the engine speed, so the time width of the asynchronous timed pulse is _τ2 , which is basically between the intake pipe pressure P _I and the engine speed N. The relational expression τ ₂ =k ₂ P _I ·N holds true. however
k ₂ is a constant. 106 is a set voltage generator that generates a set voltage V _S corresponding to the set rotation speed _N1 . A comparator 107 compares the rotation speed voltage V _N and the set voltage V _S and generates control signals for the two gates 109 and 110. When V _N ≦ V _S , an “H” level signal is supplied to the gate 109 and an “L” level signal is supplied to the gate 110, and the synchronous time pulse generator 104
A synchronized timed pulse is selected. Further, when V _N >V _S , an "H" level signal is supplied to the gate 110 and an "L" level signal is supplied to the gate 109, and the asynchronous timed pulse generated by the asynchronous timed pulse generator 105 is selected. An air-fuel ratio function voltage generator 108 generates an air-fuel ratio voltage V _M that provides a target value of the air-fuel ratio planned in accordance with the operating conditions of the engine. It is determined by comprehensively considering the air-fuel ratio of the engine, fuel efficiency, exhaust gas characteristics, drivability, etc.

As shown in this configuration diagram, when the rotation speed is below the set speed, the solenoid valve is opened every intake stroke of each cylinder of the engine to measure fuel, so the opening time of the solenoid valve is basically determined according to the intake pipe pressure. . When the engine speed is higher than the set speed, the solenoid valve is operated at a constant cycle to measure fuel regardless of the engine speed, so the opening time of the solenoid valve is determined by the product of the intake pipe pressure and the speed. In either case, the air-fuel ratio is controlled to an appropriate value within the flammable range, but the stoichiometric air-fuel ratio is defined by the equivalence ratio of the air-fuel mixture, so it is a constant value. However, in order to make the engine warm-up condition, exhaust gas purification device, fuel efficiency, etc. effective, the air-fuel ratio voltage V _M , which determines the air-fuel ratio target value, is generated by an air-fuel ratio voltage generator using detection signals such as a water temperature sensor and an oxygen concentration sensor. This allows for more precise air-fuel ratio control.

FIG. 3 shows an engine which satisfies the basic fuel metering function in an automatic engine using engine speed and intake pipe pressure as control parameters, and a specific electric circuit for this is shown in FIG. Rotation angle detector 101
is an inductor 101 engaged with the engine crankshaft.
The rotation phase of a is detected by an electromagnetic pickup 101b, and a rotation angle pulse having a repetition frequency equal to the operation frequency of the intake stroke of the engine is generated. 101
e is a stator, and 101c and 101d are waveform shaping transistors. Rotation speed voltage generator 102
generates a rotational speed voltage V _N proportional to the repetition frequency of rotational angle pulses generated by the rotational angle detector 101, 102a and 102b are transistors, 102c and 102d are diodes, and 102
e and 102f are capacitors, and 102g is a resistor. The rotational speed voltage V _N from the generator 102 is determined by the differential operational amplifier 107a of the comparator 107 in response to the set rotational speed N _S by the potentiometer of the setter 106 _. The comparator 107 generates and outputs a discrimination signal corresponding to the magnitude at the J point. That is, V
For _N <V _S , point J produces a high level signal, and for V _N >
At V _S , point J produces a low level signal. The intake pipe pressure detector 103 is a diffusion type semiconductor pressure detector 10
3a, and generates an intake pipe pressure voltage Vp proportional to the intake manifold absolute pressure P _I of the engine. 1
03b is an operational amplifier for amplification. The synchronous timed pulse generator 104 is an integral sawtooth voltage generator that generates a sawtooth voltage in synchronization with the rotation angle pulse of the rotation angle detector 101, and the sawtooth voltage generated by the intake pipe pressure detector 103. The main component is a comparator consisting of an operational amplifier 104d that compares the intake pipe pressure voltage Vp with the intake pipe pressure voltage Vp, and generates a synchronous timed pulse whose time changes according to the intake pipe pressure voltage Vp. Therefore, the time width τ ₁ of the synchronous timed pulse is basically τ ₁ =
It is determined by k ₁ Vp (k ₁ is a perfect number). 104a is an operational amplifier that constitutes an integral type sawtooth voltage generator, and its integral time constant is a capacitor 104b and a resistor 104c.
104e is a reset analog switch that is reset in synchronization with the rotation angle pulse of the rotation angle detector 101.

The asynchronous timed pulse generator 105 is a pulse generator 105 that generates clock pulses with a constant repetition frequency regardless of the engine crankshaft rotation speed.
a, an integral sawtooth wave voltage generator 105b that is reset by this clock pulse, and a comparison voltage Vr corresponding to the product of the rotational speed voltage V _N and the intake pipe pressure Vp.
and a comparator 105d that compares the sawtooth wave of the sawtooth wave voltage generator 105b and the comparison voltage Vr generated by the multiplier 105c.
The comparator 105d generates and outputs a timed pulse whose time width changes in proportion to the comparison voltage Vr. This timed pulse is generated not in synchronization with the rotation of the engine crankshaft, but in synchronization with the clock pulse generated by the pulse generator 105a.

When the engine rotation speed N is lower than the set rotation speed N _S , the gate 109 opens and the gate 110 closes, so that the synchronous timed pulse is applied as a base signal to the amplification transistor 111a of the current amplifier 111, so that the solenoid valve 7 is opened. The time is determined by a synchronized timed pulse. Further, when the engine speed N exceeds the set speed N _S , the gate 110 opens and the gate 109 closes, so the opening time of the electromagnetic valve 7 is determined by the asynchronous timed pulse. Therefore, the solenoid valve 7 synchronizes with the rotation of the engine crankshaft when the rotational speed N is less than the set rotational speed N _S and measures _the fuel every intake stroke. Fuel metering is performed in a constant, repeated synchronization regardless of rotation.

In the circuit example shown in FIG. 4, the air-fuel ratio voltage generator 108 that determines the target value of the air-fuel ratio of the air-fuel mixture supplied to the engine is connected to the potentiometer 108a.
It only generates a constant air-fuel ratio voltage V _M that does not change depending on engine operating conditions, etc.
This air-fuel ratio voltage generator 108 is connected to the cooling water temperature and the oxygen concentration in the exhaust gas by using a water temperature sensor for detecting the cooling water temperature of the engine, an oxygen concentration sensor for detecting the oxygen concentration in the exhaust gas, etc. as shown by the broken line in FIG. By generating an air-fuel ratio function voltage that determines a target air-fuel ratio voltage accordingly, it is possible to improve the starting characteristics of the engine and the warm-up characteristics of the engine and the exhaust purification efficiency of the three-way catalyst. This is omitted as it is applicable.

Further, as shown in the configuration explanatory diagram of FIG. 5 showing the main part of another embodiment, the nozzle 4 of the bench lily part 4 is
It is also possible to arrange an air pleat system in the fuel flow path leading to No. 4. In this embodiment, 45 is an emulsion tube, 46 is an air jet, 47 is an emulsion hole, and 48 is an air horn. Since emulsion air is mixed into the fuel metered by the solenoid valve 7, the fuel is injected from the nozzle 44. It is possible to improve the atomization characteristics of

As described above, in the present invention, the fuel is metered by a solenoid valve, heated by a heater using a PTC element, and then injected from the vent lily part of the engine intake system. In the high rotation range, the heater can safely vaporize the fuel without overheating the fuel, and heating can also relatively smooth the pulsations in the fuel flow, and in the high rotation range, the atomization ability of the bench lily structure can be used to achieve good atomization. can. In addition, the power supply control means energizes the heater only when heating is necessary, improving durability.
A power saving effect can be expected.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
Figure a is an electrical circuit diagram of the power supply control circuit shown in Figure 1;
Figure 2b is an electric circuit diagram of another embodiment of the power supply control circuit, Figure 3 is a block diagram of the electric control circuit shown in Figure 1, and Figure 4 is an electric circuit diagram of the electric control circuit shown in Figure 3. , FIG. 5 is a block diagram showing the main parts of another embodiment of the present invention. 3... Throttle valve, 4... Bench lily part, 4
4...Fuel nozzle, 7...Solenoid valve, 11...Electrical control circuit, 11a...Power control circuit, 15...
A PTC heater serves as a fuel heater.

Claims (1)

[Claims] 1. A solenoid valve that opens and closes in response to a synchronous timed pulse or an asynchronous timed pulse of a constant period that is emitted in synchronization with the crankshaft of an internal combustion engine, and generates the timed pulse of a predetermined time width that is supplied to the solenoid valve. an electric control means; a bench lily portion disposed upstream of an intake system throttle valve of the engine; a fuel nozzle for spouting fuel metered by the solenoid valve to the vent lily portion; A fuel heater using a PTC element that is disposed between the flow path leading to the nozzle and heats the fuel after being measured by the solenoid valve, and a power source that switches and controls the operation of this heater according to engine operating conditions. A fuel injection device comprising a control means.