JPS58180756A - Air fuel ratio controller of carburetor - Google Patents

Abstract

PURPOSE:To compensate the air fuel ratio of a floatless carburetor to a proper value which is needed at starting and warming-up of an engine by correcting the quantity of compressed air which is to be fed into an atmosphere chamber of a diaphragm chamber of the floatless carburetor, according to the informations of pressure in Venturi, pressure in an air intake pipe and water temperature of the engine. CONSTITUTION:The atmosphere chamber 8 of a pressure regulator 6 is communicated by a pressure pipe 34 to the outlet pipe 36 of a two-way solenoid valve 35. Signals from a pressure detector 47 of a large Venturi 2 and a pressure switch 49 of an air intake pipe 48 are sent to a control circuit 50, which generates and sends a signal to a coil 42 of the two-way solenoid valve 35. The starter circuit ST of a key switch 57 is connected to a thermal timer 56. The contact point 56d on the end of the bimetal 56a of a thermal timer 56 makes contact with another contact point 56b at a normal temperature. A whole body of the thermal timer is attached to a block of the engine and senses the temperature of cooling water.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention connects the atmospheric pressure in the diaphragm chamber of a floatless vaporizer with an air pressure pump through a two-way solenoid valve, and adjusts the correction amount of compressed air from the pump to The air-fuel ratio of the carburetor is determined by the connected venturi pressure, intake pipe pressure, and engine water temperature, and the air-fuel ratio of the carburetor is determined by controlling the opening and closing of the solenoid valve.

The conventional carburetor shown in Tokuto No. 56-115884 uses a control unit to control a solenoid valve that controls the air-fuel mixture ojit and another solenoid valve that opens a nozzle that connects to the venturi. ! This is used to set the mixture ratio during horizontal machine operation, but since the mixture volume is varied by changing the opening/closing ratio of both solenoid valves, the fluctuations in the mixture volume are large, and the volume of the mixture passageway may be small. As a result, large fluctuations appear in the mixture ratio, and engine rotational fluctuations become large and unstable during slow engine operation. Also, the throttle valve opens wide at low temperatures,
It is necessary to make the engine smaller with the engine so that the engine warms up more quickly, but this is not the case with this one, so after starting the engine, the viscosity of the engine speed increases, so the engine either stalls or spins at a low speed, and becomes unstable. There was a drawback.

Furthermore, during rapid acceleration during MSI, the pressure in the mixture oil passage becomes almost equal to atmospheric pressure, which delays the suction of fuel from the nozzle, which causes the mixture to become thinner, resulting in suffocation and misfires.

In view of the above, the present invention has been developed by transmitting compressed air from a pneumatic pump to an atmospheric chamber of a diaphragm chamber of a floatless vaporizer through a two-way solenoid valve to reduce the venturi pressure, V & tracheal pressure.
The correction amount of the pressure M air is determined according to the engine water temperature, and the air-fuel ratio of the carburetor is corrected to the air-fuel ratio required for starting and slowing down by closing the solenoid valve IS, thereby expanding the m1114I property.

Next, a description will be given based on one embodiment.

FIG. 1 shows a longitudinal section of the carburetor and the system.

The throat part of the large venturi (2) of the carburetor (1) (
3), the nozzle (4) faces and the fuel passage (5) is open.

There is an orifice at the tip. The other end of the fuel passage (5) opens into the fuel chamber (7) of the pressure regulator (6). The fuel chamber (7) and atmospheric chamber (8) are connected to the diaphragm (9).
The atmospheric chamber (8) communicates with the air passage αV of the carburetor (1) through the throttle MK. A shell (6) is fixed to the diaphragm (9), and a hook ring is formed by partially bending the shell (b). One end of the lever (141) is movably supported on the hook (to the bottle) by a hole □□□ of the hook (to), and the other end of the lever (141 is attached to the needle seat ( B)
The needle is in contact with the head of the needle guided by the needle. The other end of the needle is in contact with the seat portion of the needle seat (6). 2 is a spring that urges the diaphragm (9) to the right. The fuel inlet (2) is connected to the fuel tank (
2).

The throttle pore portion (2) of the carburetor (1) has a throttle valve (E) fixed to a throttle shaft. A throttle lever member is fixed to one end of the throttle shaft. The upper end of the throttle lever (2) is in contact with the tip of a lever that is locked with a bottle supported on the main body of the carburetor (1). The lever handle is biased to the left by the fly handle. The container (to) contains a heat-sensitive body 6η, and the rondo (2), which moves forward and backward according to its temperature, pushes the lever @ all to the right.

The left end of the thermosensitive expansion body 0υ is in contact with a heating element such as a PTC thermistor.

The atmospheric chamber (8) is communicated with the outlet pipe (to) of the three-way solenoid valve (to) by a pressure pipe, and the base of the outlet pipe (to) is connected to the seat (to).
b). The sheet (b) is pressed to the left by the pulp (to) and the spring (to) for sealing. The ring is a plunger, - is a fixed magnetic pole, the ring is a coil, and the ring is an inlet pipe. Inlet pipe is pressure regulator n
It is connected to the pneumatic feed pump via t. The throat portion (3) of the large venturi (2) has an open end q#-, and the other end is connected to a pressure sensor. Intake pipe-
A pipe is connected to the outlet and a pressure switch is connected to the pipe. Signals from the pressure detector 17) and the pressure switch are input to the control circuit, and the output signal from the &IJ 1141 circuit is input to the coil ring of the three-way solenoid valve.

- is the vehicle's key switch, and the ring is the battery.

Figure 2 shows the control circuit diagram.

The inverting input terminal of the inverting amplifier m- is connected to a common connection point of a series connection of a resistor (R1) and a thermistor (Th), one end of which is connected to a constant voltage VDD lower than the voltage of the battery. The other end of the thermistor (Th), which is a temperature detector, is grounded. Also, this connection point is a pressure sensor @
is grounded through. The pressure sensor IIS*- is set to vary linearly depending on the pressure value, and is set so that the negative pressure is large but the resistance is large. Further, a series connection of a resistor (R2) and a pressure switch is connected in parallel with a thermistor (Th). When the negative pressure is low, the contacts of the pressure switch are open.

The starter circuit (ST) of the key switch is connected to the thermal timer. The contact (56(1)) at the tip of the bimetal (+S a a) of the thermal timer is normally in contact with the normal temperature contact (56b). (56c)
is a heater, and the entire thermal timer is attached to the engine block to sense the temperature of the cooling water.The zero contact (56b) is grounded via the relay coil (b4b). A relay contact (541L>) and a resistor (R3) are connected in series between VDD and (R2).

The output terminal of the inverting amplifier is connected to the inverting input terminal of the comparator, and the output of the square wave oscillator is connected to the non-inverting input terminal of the integrator.
is converted into a triangular wave and input. The output of the comparator is connected to an amplifier, and a 1tQ stage transistor (TR
Diode (D) and three-way solenoid valve (2) in the collector of x)
One end of the parallel connection of the coil is connected, and the other end (10B) is connected to the ignition circuit (IG) of the key switch ■,
Connected to the battery's anode.

Figure 3 is a relationship diagram between intake air %jiGa and air-fuel ratio A/F,
The second figure shows the relationship between the air cover and the inverting input terminal voltage V of the inverting amplifier, and shows the value when the relay contact (54m) is open. 1lhS diagram shows the relationship between water temperature and voltage V, 6th
The figure shows the relationship between the operating point of the pressure switch and the voltage (2), and the 78th figure shows the control waveform in the electric circuit.

Next, the operation of the embodiment shown in the drawings will be explained.

When the key switch ring is rounded and put into the starter circuit (ST), current flows through the heater (56c) and the bimetal (56-) gradually heats up.The heat from the heater (56-) is transferred from the thermal timer body to the engine cooling water. You can also tell
The change in the deflection angle of the bimetal (56 m) is inversely proportional to the temperature and pressure of water, and becomes slower at low temperatures. Therefore, when the temperature is low, the time when the bimetal contact (56Q) is separated from the contact (56b) becomes longer. Therefore, during cranking, the coil (+4b) of the relay is energized and the contact (54&
) is closed, and the inverting input terminal voltage υ of the inverting amplifier II) becomes the first
The voltage will be slightly lower than the voltage with the characteristics shown in the figure. At this time, by turning the key switch, the pneumatic pump is activated.
Compressed air at constant pressure by regulator t-tortoise valve cw
' to the atmospheric chamber (8). At this time, a part of the compressed air escapes to the air passage συ via the orifice Sakaki, but the atmospheric chamber (8) is maintained at a certain pressure value.
As the engine rotates further, the fuel pump)
operates, fuel is pumped out from the fuel tank, and the pressure is regulated to a constant level by the regulator (2).
It is sent to the fuel chamber (7) via IS#, and the fuel passage (
Although it is discharged to the venturi section through the 58 orifice 1, it is maintained at a constant amount determined by the pressure balance between the spring 6 and the atmospheric chamber (8). At this time, the input voltage V of the inverting amplifier wheel, which is higher than the voltage shown in Figure 1, is inverted and amplified, so the output voltage of the inverting amplifier wheel becomes a low level, and the comparator outputs a triangular wave from the integrator. By comparison, the intake air jl shown in the m7 diagram
As in the case where Ga is large, the pulse width of the output voltage of the comparator becomes wider as shown by the solid line, and the three-way solenoid valve (3-way solenoid valve) is opened with this pulse width by the amplifying wheel, and the output voltage of the comparator (to the A large amount of compressed air is pumped into the air pump via the regulator. Therefore, the number of fuel dischargers increases, and an air-fuel ratio of /w7J is obtained.

Then, when the key switch is released after a complete explosion, the ignition 11% (IG
), and the power supply to the thermo switch is stopped.

When the key switch Q switches to the ignition circuit (IG), the voltage V decreases to the value shown in Figure 4, and the 7743
The air-fuel ratio shown in the figure is the starting value air-fuel ratio (approximately 10).

As the engine gradually comes to rest and rises, the servo star (
'rh) resistance value decreases, the input voltage V decreases, and the output voltage of the inversion amplification axis increases, so the output pulse width at the comparator gradually decreases, and the air-fuel ratio The air-fuel ratio is gradually corrected to around 75 after io'tii and becomes the air-fuel ratio after warming up, but at this time, as the engine is slowed down, the engine oil becomes softer, the fuel vaporizes more, and the engine speed increases. I'll come. This rotational speed is normally set at a maximum of 20OO to 300 to prevent it from becoming abnormally high.
It is necessary to keep it at 0 rpm. Therefore, the amount of heat generated by energizing the PTC thermistor (to) at the time of startup heats the heat-sensitive expansion body C1I, and the internal wax gradually dissolves from the solid phase to the liquid phase.

This causes volumetric expansion of the wax (Rondo (2
) extends to the right, rotates the lever @ to the left, and gradually returns the lower ) k / (- (2)), so the engine speed reaches a maximum of 2000 to 3000 rpm, and when it is loosened. The throttle valve (2) is returned to the closed position required for idling.

When you press the accelerator pedal to drive, the throttle valve (to) is opened greatly, the intake air cover increases, the venturi pressure increases, the resistance value of the pressure detector increases, and therefore the input voltage V increases. , the output voltage of the reversing amplifier wheel decreases, the output pulse width of the comparator increases in comparison with the triangular waveform with the tank divider, and therefore the discharged fuel from the fuel chamber (7) increases and the air amount increases. Even if the air-fuel ratio increases, the air-fuel ratio is maintained at a constant value.

If the accelerator pedal is depressed rapidly, the intake pipe pressure will drop significantly, for example, to become less than -≦Q mat, the contact of the pressure switch will open, and the input voltage will further rise, and therefore the three-way solenoid valve (2 )tPH<pulse width becomes wider and the output air-fuel ratio is corrected to about 72. In this way, during sudden acceleration, the fuel is injected without delay, so there is no misfire or suffocation.

The thermal timer is effective for restarting after **. Fuel vaporization is good until the engine has stopped and cooled down sufficiently.The multi-timer's operating time must be made shorter. Therefore, when the water temperature is relatively low, bimetallic (
56m) is also reduced, so that its contacts are opened in a short period of time, and care is taken to ensure that the mixture does not become rich at lI&'Nt at the time of restart, making restart impossible. It is even better if the fuel pump is motor-driven or solenoid-driven because the pressure will be constant as soon as the key switch is turned on.

According to this invention, the following effects are expected.

(1) There is no float chamber, so there is no difference in the mounting direction.

(2) Since there is only one fuel discharge system, there is no problem with connecting the slow system to the main system, which occurs in conventional carburetors.

(3) Starting warm-up function Since there is no inflow resistance found in auto choke mechanisms, output can be increased during warm-up.

(4) Since all fuel is injected, fuel atomization is good.

(j) Since the fuel is not measured by the positive venturi, the venturi pressure can be reduced and the output at full load can be increased.

(6) Smooth engine rotation from cranking to slow engine and full load operation. In particular, the large volume of the atmospheric chamber of the regulator (6) absorbs the pulsation caused by the closing of Ia of the three-way solenoid valve (2), thereby stabilizing the engine rotation.

(7) When the key switch is turned off, the regulator (6)
The spring pushes the diaphragm to the right, and the air in the atmospheric chamber (8) is released through the throttle mt-, increasing the volume of the fuel chamber and also preventing fuel from dripping.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional diagram and system diagram of the carburetor of this invention, Figure 2 is an electric circuit diagram, and Figure 3 (2) is an air-fuel ratio characteristic diagram.
Figure 5 is a relationship diagram between air volume and voltage, Figure 5 is a relationship diagram between water temperature and voltage, Figure 4 is a pressure switch characteristic diagram, 5117
The figure is a control mg characteristic diagram of an electric circuit. (1)... Floatless vaporizer (4), book, nozzle (6), e, regulator (8)... in the atmospheric chamber)... three-way solenoid valve 10... air pressure pump U...・Pressure detector wheel...Control circuit wheel...Comparator (Th)...Thermistor (temperature detector) Patent applicant Aisan Kogyo Co., Ltd.

Claims (1)

[Claims] An air pressure pump that forces compressed air into the atmospheric chamber of the vaporizer regulator, a pressure sensor that detects venturi pressure, and a temperature sensor that detects water, connected to a solenoid valve that continues the compressed air. An air-fuel ratio control device for a carburetor, characterized in that the signal tube receiver from the pressure detector and the temperature detector is comprised of a control circuit that controls the duty ratio in relation to the pressure and water temperature using a comparator.