printable version

Carburetor Nikki 30/34

Carburetor Nikki 30/34 and heater of an inlet collector

Air damper control mechanism heats the engine coolant.

Design

Carburetor Aisan, mounted on a vehicle Mazda, a vertical triple carburetor with a serial throttle. Drive throttle secondary chamber vacuum. Adjusting the automatic choke (if fitted) is carried bimetallic coil with electric heating or thermal wax capsule, heated engine coolant.

The carburettor consists of three main components. This is the cover of the carburettor, the carburettor and throttle body (which establishes the throttles). The insulating block located between the housing and the carburetor throttle body, serves to protect the body from excessive carb heat transfer.

Some models have a carburettor Nikki electric heater mounted on the inlet manifold (see. Fig. Carburetor Nikki 30/34 and heating the intake manifold). The heater is designed to prevent carburetor icing and improve atomization of the fuel mixture in the engine warming. The temperature switch is used to switch off the heater when the temperature reaches a certain level. The heater has a positive temperature coefficient of resistance - with an increase in temperature increases the resistance heater.

Specifications

Adjust the supply air temperature (hot air system)

System of adjustment of temperature of arriving air

Damper the inlet air cleaner is opened or closed, depending on the temperature in the engine compartment. The vacuum from the intake manifold is supplied through a thin hose on the vacuum diaphragm, which controls the position of the valve in the air intake duct. Another hose connects the first hose (via T-joints) with a temperature sensor disposed in the air filter housing. Temperature sensor is a bimetallic valve opens and closes the vent. When the temperature rises in the engine compartment, the valve opens to allow air, which leads to the elimination of the vacuum in the vacuum diaphragm.

When the temperature in the engine compartment is low, the bimetallic valve is closed and the vacuum acts on the diaphragm vacuum which opens the shutter completely. Hot air from the exhaust manifold flows into the intake passage of the carburetor. When the temperature in the engine compartment rises, the bimetallic valve begins to open, which reduces the negative pressure exerted on the diaphragm vacuum that begins to close the damper.

Now enters the carburetor mixture of hot air and the cool outside air. When the temperature in the engine compartment rises above about 30 ?� C, the bimetal valve is fully open; flap completely closes flow of hot air from the exhaust manifold. The carburetor comes already warm air from the engine compartment. Thus, the temperature of the air entering the carburetor is maintained approximately constant regardless of the outside air temperature (or the temperature in the engine compartment).

Additional vacuum valve can be used to maintain a constant supply of hot air with a sharp acceleration.

On some models used bimetallic spring, which is directly connected to the choke. Bimetallic spring directly controls the air damper opening or closing it, depending on the ambient temperature.

The system of temperature control air intake using a bimetallic valve

Domestic fuel and air valves

The dosing system

Fuel is supplied to the carburetor passes through a fine strainer. The fuel level in the float chamber is regulated with a needle valve or a plastic float.

The float chamber has an internal vent that goes to the area of the air filter.

The idling and the transitional system

Fuel from the fuel enters the well through a calibrated orifice of the idle channel to idle. Here, the fuel is mixed with a small amount of air flowing through a calibrated air jet. Further, the fuel mixture passes through the nozzle with a reduced flow section. The resulting mixture passes through a channel and is discharged from the throttle hole under the primary chamber. Tapered mixture adjusting screw is used to change the passage orifice, which allows an accurate adjustment of the idle mixture. Several transient openings (or groove transitional regime) provide enrichment of the mixture when they open throttle opening. This system ensures the absence of failures in the operation of the engine at the time of opening of the throttle.

The speed of the engine at idle speed is adjusted using the adjusting screw. The adjusting screw is twisted so that exhaust emissions conform to the standards and covered by a cap.

Valve fuel cut

1. The air jet system of idling - the primary chamber 2. Valve fuel cut 3. The fuel jet of system of idling - the primary chamber 4. Throttle - the primary chamber 5. Holes transitional regime - the primary chamber 6. The amount of the mixture adjustment screw idling A. To the main fuel jet of the primary chamber

Fuel cut valve is used to prevent the flow of fuel to the engine after the engine is switched off. The valve has an operating voltage of 12 volts and uses a plunger to lock the channel idle when you turn off the ignition.

On some models, the valve is controlled by an electronic control unit. The valve can also be operated with a strong reduction of the engine speed at closed throttle. This allows you to save fuel and reduce exhaust emissions. When the engine speed drops below a certain level, or if the throttle is opened, the electronic control unit opens the valve and the normal fuel supply is restored. Connecting the electronic control unit varies depending on the model.

The system of a lean fuel mixture at reducing the frequency of rotations of the crankshaft (installed on some models)

By reducing the frequency of the crankshaft speed solenoid valve depletion of the fuel mixture passes an additional amount of air into the secondary mixing chamber of the carburetor. The system helps to improve combustion and thereby reduce the content of unburnt hydrocarbons in the exhaust gases.

The system of enrichment of a fuel mix with a decrease in the frequency of rotations of the crankshaft (installed on some models)

By reducing the frequency of the crankshaft speed solenoid valve of system of enrichment of the fuel mixture passes an additional amount of air and fuel into the secondary mixing chamber of the carburetor. The system helps to improve combustion and thereby reduce the content of unburnt hydrocarbons in the exhaust gases.

Fuel from the fuel well in the secondary chamber receives processing channel through a calibrated nozzle. Here it is mixed with a small amount of air entering through two calibrated air jets. The resulting mixture flows through the passage and discharged from a throttle valve opening of the secondary chamber. The system is controlled by an electronic control unit. The system is activated at lower engine speed of the crankshaft to the 1500 - 2300 rev / min. The electronic control unit receives information from the switch on the throttle and ignition coils, and on the basis of information received determines when to energize the solenoid valve.

Throttle damper (installed on some models)

When the throttle valve is abruptly closed, the intake manifold vacuum increases sharply, it can lead to evaporation of the fuel droplets which are on the walls of the intake manifold. This additional fuel is often passes through the cylinders of the engine, without burning through, resulting in increased content of unburned hydrocarbons in the exhaust gases. Also, on models with automatic transmission or emission control system drastic depletion of the fuel mixture can cause bad pick-up motor or the engine may even stall. Vacuum damper throttle allowing the throttle to close gradually, which reduces the speed of the engine, does not increase the toxicity of exhausts, and without disturbing the operation of the engine.

Positioning the throttle mechanism when lowering the engine speed (set to some models)

1. Ignition Switch 2. Battery 3. The ignition coil 4. The electronic control unit 5. Aperture 6. Throttle primary Camera

7. The intake manifold 8. Carburetor 9. The vacuum from the intake manifold 10. The solenoid valve positioning system Throttle

Positioning mechanism works similarly to the throttle damper throttle. However, the positioning mechanism is controlled by a solenoid valve and an electronic control unit to the throttle valve remains slightly open with a decrease in engine speed of the crankshaft. The diaphragm mechanism positioning the throttle is usually used as a system of stabilization of idling.

System to increase the engine speed when idling (model hydrostrengthening steering)

Vehicles with hydrostrengthening steering system can be used to increase the engine speed at idle, which is activated when you turn the steering wheel. As the pump system hydrostrengthening steering actuator receives from the engine, then when you turn the steering wheel and turn on the pump, the engine speed is at idle is reduced.

When you turn the wheel in the switch hydrostrengthening steering solenoid valve closes the circuit system to increase engine speed. Vacuum is supplied to the diaphragm positioning mechanism throttle, which is slightly opens the throttle. When the load is removed from the engine, the switch system hydrostrengthening steering opens and closes the solenoid valve intake vacuum on the diaphragm; vacuum at the diaphragm disappears and the throttle returns to normal idle position.

The temperature compensator system idling at high engine temperatures - some models

The temperature compensator system idling at high engine temperature is a temperature sensitive device, which is installed between the intake pipe of the air filter and the intake manifold. It serves to prevent poor performance of the engine hot (after prolonged use of engine idling in hot weather, for example). When the temperature in the engine compartment becomes too high, the fuel in the float chamber expands and its level rises, resulting in the formation of the mixture is too rich. Temperature compensator serves to supply additional air to prevent the formation of a supersaturated mixture.

The compensator is closed at normal temperature in the engine compartment. When the temperature in the engine compartment goes above 67 ?� C, the valve starts to open, and an additional amount of air supplied to the intake manifold vacuum for saturated fuel mixture. Compensator fully opened when the temperature in the engine compartment rises above 71 ?� C. When the temperature in the engine compartment is returned to the normal level (below 71 ?� C), the valve closes, stopping the flow of air.

Pump Accelerator

The pump-accelerator piston controlled carburettor Nikki. The drive control of the pump and a mechanical accelerator is carried by a lever mechanism connected to the throttle valve of the primary chamber.

When the accelerator pedal arm coupled to the connecting mechanism throttle pushes the piston booster pump. Fuel from the pump chamber is pushed into the outlet ducts of the pump through the outlet valve (with a small weight) and enters the mixing chamber through a pump sprayer. The inlet (ball) valve remains closed so that the fuel has not got back to the float chamber.

When the accelerator pedal is released, the spring returns the piston to its original position. The vacuum pulls a new portion of fuel from the float chamber into the pump chamber through the outlet (ball) valve.

Home metering system

The amount of fuel discharged into the air flow is controlled by a calibrated main fuel jet. Fuel is supplied through the main fuel jet fuel into the bottom of the vertical well that is lowered into the lower end of the fuel in the float chamber. Emulsion tube, closed air jet is installed in the well. Fuel is mixed with the air flowing through the air jet and the emulsion through the holes in the tube, the resulting emulsified mixture was discharged through a dispenser in the primary chamber of the carburettor diffuser.

The enrichment of the fuel mixture at part load engine

The air channel is of zadrosselnogo space concentrating chamber. With the engine at idle and at low throttle, the vacuum from the intake manifold in the channel diverts the plunger valve on the enrichment of the fuel mixture. The valve is closed by closing the fuel outlet channel. With increasing engine speed, when the throttle is opened more, negative pressure in the intake manifold decreases. The plunger returns to its initial position under the pressure of a spring and presses on the valve which opens a fuel passage. Fuel from the float chamber through the channel enters the main fuel pit; fuel level in the well is increased, which leads to the formation of a fuel rich mixture.

The work of the secondary chamber of the carburettor

The air channel is, in primary and secondary mixing chamber of the carburetor. The air flows coming from these channels into a common channel that leads to the diaphragm that controls the throttle position of the secondary chamber. At low engine speed is enabled only the primary mixing chamber. When the rate of air flow through the primary chamber reaches a certain level, the vacuum acts through the channel aperture of the secondary chamber, which opens the throttle valve of the secondary chamber. The vacuum formed in the secondary chamber, further controls the rate of throttle opening of the secondary chamber.

The connection mechanism throttle primary chamber serves to prevent the throttle opening of the secondary chamber when the air velocity is too high, but the accelerator pedal is not depressed. The secondary camera will not be activated until the throttle primary chamber is opened by about half. After the opening of the throttle valve of the secondary chamber, the work of the metering system is similar to the secondary chamber of the main dosing system.

Jet transition mode is used to prevent failures in the engine when the throttle valve begins to open the secondary chamber. Fuel from the secondary chamber of the well passes through a calibrated orifice. Then, it is mixed with air supplied through a calibrated air jet, to form a fuel emulsion. This emulsified mixture is discharged into the secondary mixing chamber through the opening transient, when the throttle valve begins to open the secondary chamber.

Mechanical air damper

Wheel drive air damper rope. When the control button on the instrument panel is extended, the connecting cable moves the lever that forces the air damper to close the air intake. Fast idling mode is switched by a cam connected to the choke lever. The adjusting screw mounted on the throttle lever and abuts the cam is used to adjust the engine speed with the engine in a mode of fast idling.

The opening of the air damper

After starting the engine, the air damper should be slightly parted to produce less saturated fuel mixture and prevent overflow of fuel. This is accomplished by using intake manifold negative pressure which acts on the diaphragm; the connecting mechanism of the diaphragm opens the choke.

Automatic choke

Some models have a carburettor Nikki automatic trigger. Air damper is regulated by a bimetal coil with electric heating (semi-automatic choke) or wax temperature switch, heated engine coolant (fully automatic choke).

Semi-automatic air flap

To adjust the position of the semi-automatic air damper is used bimetal coil with electric heating. System to its original state if slowly squeeze the accelerator pedal once or twice. After starting the engine power from the generator is supplied to the ceramic heater, which heats up quickly. The heat is transferred to the bimetallic spiral through the sleeve; when the bimetallic coil is heated, it is unwound by opening the choke.

Fully automatic choke

To adjust the automatic choke is used wax capsule. The capsule is heated by the engine coolant. With a low coolant temperature wax capsule is fully compressed - air damper is closed. After starting the engine and during the warm heat from the heating of the engine coolant affects the wax capsule, which is gradually expanding; expanding the capsule is gradually opening the choke. When the coolant temperature reaches normal operating level, the air damper is fully open.

Both

After starting the engine, the air damper should be slightly parted to produce less saturated fuel mixture and prevent overflow of fuel when the engine is idling and poorly throttle. This is accomplished by using intake manifold negative pressure which acts on the diaphragm; the connecting mechanism of the diaphragm opens the choke. On some models the second aperture opening. It is controlled by thermal vacuum valve and is used to ensure that when the engine temperature rises above a certain value choke also opened stronger.

Fast idling mode is enabled by a cam gear connected to the choke valve shaft via a connecting rod. Fast idle lever connected to the throttle lever, presses the toothed cam. When the bimetallic coil is heated and air damper is opened, the lever is lowered by the cam teeth. Thus, the idle speed gradually decreases until the cam fast idling is not free, and the idle speed is reduced to normal. Adjustment screw connected with a lever fast idling, can be used to adjust the fast idling speed.

If the throttle is fully open when the engine temperature is low, negative pressure at the diaphragm air damper will disappear, which will lead to the closure of the choke. This may cause overflow of fuel. To prevent this, a mechanism is used partly open choke valve. When the throttle is fully opened, the throttle lever is lowered to slightly lift the choke.