Mazda 626

1991-1998 of release

Repair and car operation

Nikki 30/34 carburetor and heater of an inlet collector

Design

The Aisan carburetor established on Mazda cars, is the two-chamber vertical carburetor with consecutive opening of throttles. Drive of a throttle of the secondary chamber the vacuum. Adjustment of an automatic air zaslonka (if it is established) is carried out by a bimetallic spiral with electric heating or the temperature wax capsule which is heated up by cooling liquid of the engine.

The carburetor consists of three main knots. It is a carburetor cover, the case of the carburetor and the case of throttles (in which butterfly valves are established). The isolating block located between the case of the carburetor and the case of throttles, serves for protection of the case of the carburetor against excessive transfer of heat.

Some models of the Nikki carburetor have the electric heater established on an inlet collector (see fig. Nikki 30/34 carburetor and heater of an inlet collector). The heater serves for prevention of an icing of the carburetor and for improvement of dispersion of a fuel mix at engine warming up. The temperature switch serves for heater switching off when the temperature of the engine will reach a certain level. The heater has positive temperature factor of resistance – at increase in temperature, resistance of a heater grows.

Technical characteristics

Adjustment of temperature of arriving air (system of supply of hot air)

System of adjustment of temperature of arriving air

Zaslonka of the inlet channel of the air filter opens or closed depending on temperature in an impellent compartment. Depression from an inlet collector arrives through a thin hose on a vacuum diaphragm which supervises the provision of a zaslonka in the channel of a fence of air. One more hose connects the first hose (through troynikovy connection) to the temperature sensor located in a casing of the air filter. As the sensor of temperature the bimetallic valve closing and opening the ventilating channel serves. When the temperature in an impellent compartment rises, the valve opens, passing air that leads to depression elimination at a vacuum diaphragm.

When temperature in an impellent compartment low, the bimetallic valve is closed and depression influences a vacuum diaphragm which completely opens a zaslonka. Hot air from a final collector arrives to the intaking canal of the carburetor. When the temperature in an impellent compartment rises, the bimetallic valve starts to open that reduces the depression influencing a vacuum diaphragm which starts to close a zaslonka.

Now in the carburetor the mix of hot air and cold external air arrives. When the temperature in an impellent compartment rises above about 30 ° With, the bimetallic valve completely opens; the zaslonka completely closes intake of hot air from a final collector. In the carburetor already warm air from an impellent compartment arrives. Thus, the air temperature, arriving in the carburetor, is supported approximately by a constant irrespective of temperature of external air (or temperatures in an impellent compartment).

The additional vacuum valve can be used for maintenance of continuous supply of hot air at sharp acceleration.

On some models the bimetallic spring which is directly connected to an air zaslonka is used. The bimetallic spring directly regulates the provision of an air zaslonka, opening or closing it, depending on air temperature.

System of adjustment of temperature of taken-away air with use of the bimetallic valve

Internal fuel and air valves

Dosing-out system

Fuel arrives in the carburetor, passing through the small mesh filter. Fuel level in the poplavkovy chamber is regulated by the needle valve or a plastic float.

The Poplavkovy chamber has the internal ventilating channel leaving to area behind the air filter.

System of idling and transitional system

Fuel from a fuel well arrives through the calibrated jet of system of idling to the idling canal. Here fuel mixes up with a small amount of the air arriving through the calibrated air jet. Further, the fuel mix passes through a jet with the reduced section through passage. The formed mix passes through the channel and is issued from an opening under a butterfly valve of the primary chamber. The conic screw of adjustment of a mix is used for change of section of an opening through passage that allows to carry out exact adjustment of quantity of a mix of idling. Some openings of a transitional mode (or a groove of a transitional mode) provide mix enrichment when they open when opening butterfly valve. The specified system provides lack of failures in operation of the engine at the moment of throttle opening.

Speed of operation of the engine in a mode of idling is regulated by means of the adjusting screw. The adjusting screw is twirled so that toxicity of exhaust gases corresponded to norm, and closed by a cap.

Valve of interruption of supply of fuel

The valve of interruption of supply of fuel is used for receipt prevention in the fuel engine after engine switching off. The valve has working tension of 12 Volts and the plunzher for blocking of the channel of idling at ignition switching off uses.

On some models the valve is supervised by the electronic control unit. The valve also can be involved at strong reduction of frequency of rotation of a cranked shaft at the closed butterfly valve. It allows to save fuel and to reduce toxicity of exhausts. When frequency of rotation of a cranked shaft decreases below a certain level or if the butterfly valve opens, the electronic control unit is opened by the valve and normal supply of fuel is restored. Connection of the electronic control unit differs depending on model.

System of pauperization of a fuel mix at decrease in frequency of turns of a cranked shaft (it is established on some models)

At decrease in frequency of turns of a cranked shaft the electromagnetic valve of system of pauperization of a fuel mix passes additional amount of air in the secondary mixing chamber of the carburetor. The system promotes improvement of combustion of fuel and, therefore, reduction of the content of not burned down hydrocarbons in exhaust gases.

System of enrichment of a fuel mix at decrease in frequency of turns of a cranked shaft (it is established on some models)

At decrease in frequency of turns of a cranked shaft the electromagnetic valve of system of enrichment of a fuel mix passes additional amount of air and fuel in the secondary mixing chamber of the carburetor. The system promotes improvement of combustion of fuel and, therefore, reduction of the content of not burned down hydrocarbons in exhaust gases.

Fuel from a fuel well of the secondary chamber arrives to the concentrating canal through the calibrated jet. Here it mixes up with a small amount of the air arriving through two calibrated air jets. The formed mix passes through the channel and is issued from an opening under a butterfly valve of the secondary chamber. Work of system is supervised by the electronic control unit. The system is activated at decrease in frequency of turns of a cranked shaft from 1500-2300 rpm. The electronic control unit receives information from the switch on a butterfly valve and ignition coils, and on the basis of received information defines, when it is necessary to submit tension on the electromagnetic valve.

Butterfly valve damper (it is established on some models)

When the butterfly valve is sharply closed, in an inlet collector there is a sharp increase in depression, it can lead to evaporation of droplets of the fuel being on walls of an inlet collector. This additional fuel often passes through engine cylinders, without burning down up to the end that leads to increase of the content of not burned down hydrocarbons in exhaust gases. Also, on models with an automatic transmission or system of fall of toxicity of exhausts sharp pauperization of a fuel mix can be at the bottom of bad acceleration performance of the engine or the engine can decay in general. The vacuum damper of a butterfly valve allows a butterfly valve to be closed gradually that reduces speed of operation of the engine, without leading to increase of toxicity of exhausts, and without breaking operation of the engine.

The mechanism of positioning of a butterfly valve at decrease in frequency of turns of the engine (it is established on some models)

1. Ignition lock 2. Accumulator 3. Ignition coil 4. Electronic control unit 5. Diaphragm 6. Butterfly valve of the primary chambers

7. Inlet collector 8. Carburetor 9. Depression from an inlet collector 10. Electromagnetic valve of system of positioning of a butterfly valve

The mechanism of positioning of a butterfly valve works similar to a butterfly valve damper. However the mechanism of positioning is supervised by the electromagnetic valve and the electronic control unit in order that the butterfly valve remained frequency of turns of a cranked shaft a little slightly opened at decrease. The diaphragm of the mechanism of positioning of a butterfly valve usually also is used by system of stabilization of idling.

System of increase in frequency of rotation of a cranked shaft when idling (model with steering hydrostrengthening)

Cars with hydrostrengthening of a steering can use system of increase in frequency of rotation of a cranked shaft when idling which is activated at turn of a steering wheel. As the pump of system of hydrostrengthening of a steering receives a drive from the engine, at turn of a steering wheel and turning on of the pump, frequency of rotation of a cranked shaft when idling decreases.

At turn of wheels the switch in system of hydrostrengthening of a steering closes a chain of the electromagnetic valve of system of increase in frequency of rotation of a cranked shaft. Depression arrives on a diaphragm of the mechanism of positioning of a butterfly valve which slightly opens a butterfly valve a little. At removal of loading from the engine, the switch of system of hydrostrengthening of a steering disconnects a chain, and the electromagnetic valve closes receipt of depression on a diaphragm; depression at a diaphragm vanishes and the butterfly valve comes back to the normal provision of idling.

The temperature jack of system of idling at high temperature of the engine – some models

The temperature jack of system of idling at high temperature of the engine is the device sensitive to temperature which is established between an intaking branch pipe of the air filter and an inlet collector. It serves prevention of bad operation of the engine in a hot condition (at long operation of the engine in an idling mode in hot weather, for example). When the temperature in an impellent compartment becomes too high, fuel in the poplavkovy chamber extends, and its level rises that leads to formation of too saturated mix. The temperature jack serves for giving of additional amount of air to avoid formation of the oversaturated mix.

The jack is closed at normal temperature in an impellent compartment. When the temperature in an impellent compartment rises above 67 ° With, the valve starts to open and the additional amount of air arrives in an inlet collector for depression of a saturated fuel mix. The jack is completely open, when the temperature in an impellent compartment rises above 71 ° S.Kogda temperature in an impellent compartment comes back to normal level (below 71 ° C), the valve is closed, stopping supply of air.

Pump accelerator

Operation of the pump accelerator of the Nikki carburetor is supervised by the piston. The drive of management of the pump accelerator mechanical also is carried out by means of the lever connected to the mechanism of management of a butterfly valve of the primary chamber.

By pressing an accelerator pedal the lever connected with the connecting mechanism of a butterfly valve, presses on the pump accelerator piston. Fuel from the chamber of the pump forces the way to final canals of the pump via the final valve (with gruziky) and arrives in the mixing chamber through a pump spray. The inlet (ball) valve remains is closed in order that fuel did not get back to the poplavkovy chamber.

When the pedal of an accelerator is released, the spring returns the piston in a starting position. Depression tightens a new portion of fuel from the poplavkovy chamber in the pump chamber via the final (ball) valve.

The main dosing-out system

The amount of the fuel which is let out in an air stream, is supervised by the calibrated main fuel jet. Fuel arrives through the main fuel jet in the basis of a vertical fuel well which is lowered by the bottom end in fuel in the poplavkovy chamber. The emulsion tube closed by an air jet, is established in a well. Fuel mixes up with the air arriving through an air jet and through openings in an emulsion tube, the turned-out emulgirovanny mix is issued through a spray in a diffuzor of the primary chamber of the carburetor.

Enrichment of a fuel mix at incomplete loading of the engine

The air channel goes from zadrosselny space to the concentrating chamber. At operation of the engine in a mode of idling and at small opening of a butterfly valve, depression from an inlet collector in the channel is taken away by a plunzher from the valve of enrichment of a fuel mix. The valve is closed, closing the final fuel channel. At increase in speed of operation of the engine when the butterfly valve opens more strongly, depression in an inlet collector decreases. Plunzher comes back to a starting position under the pressure of a spring and presses on the valve which opens the fuel channel. Fuel from the poplavkovy chamber via the channel arrives in the main fuel well; fuel level in a well raises that leads to formation of more saturated fuel mix.

Operation of the secondary chamber of the carburetor

The air channel is, both in primary, and in the secondary mixing chamber of the carburetor. Air streams from these channels arrive to one general canal which conducts to a diaphragm supervising the provision of a butterfly valve of the secondary chamber. At low speed of operation of the engine only the primary mixing chamber is involved. When speed of the air stream passing through the primary chamber, reaches a certain level, depression influences via the channel a diaphragm of the secondary chamber which opens a butterfly valve of the secondary chamber. The depression formed in the secondary chamber, supervises further speed of opening of a butterfly valve of the secondary chamber.

The connecting mechanism of a butterfly valve of the primary chamber serves for prevention of opening of a butterfly valve of the secondary chamber when speed of an air stream is too high, but the pedal of an accelerator is not pressed. The secondary chamber will not be involved, while the butterfly valve of the primary chamber will not be open approximately half. After opening of a butterfly valve of the secondary chamber, work of dosing-out system of the secondary chamber is similar to work of the main dosing-out system.

The jet of a transitional mode is used for prevention of failures in operation of the engine when the butterfly valve of the secondary chamber starts to open. Fuel from a fuel well of the secondary chamber passes through the calibrated jet. Then, it mixes up with the air arriving through the calibrated air jet, with formation of the fuel emulsion. This emulgirovanny mix is issued in the secondary mixing chamber, through an opening of a transitional mode when the butterfly valve of the secondary chamber starts to open.

Mechanical air zaslonka

Drive of a mechanical air zaslonka the hummock. When the management button on the dashboard is extended, the connecting rope moves the lever which forces an air zaslonka to close the channel of a fence of air. The mode of fast idling joins by means of a cam connected to the lever of an air zaslonka. The adjusting screw established on the lever of a butterfly valve and resting against a cam, is used for adjustment of frequency of rotation of a cranked shaft at operation of the engine in a mode of fast idling.

Opening of an air zaslonka

After engine start, the air zaslonka should be slightly opened a little for formation of less saturated fuel mix and prevention of a modulation of fuel. It is reached by use of depression of an inlet collector which influences a diaphragm; the connecting mechanism of a diaphragm opens an air zaslonka.

Automatic air zaslonka

Some models of the Nikki carburetor have the automatic starting arrangement. The provision of an air zaslonka is regulated or a bimetallic spiral with electric heating (a semi-automatic air zaslonka) or the temperature wax switch which is heated up by cooling liquid of the engine (completely automatic air zaslonka).

Semi-automatic air zaslonka

For adjustment of provision of a semi-automatic air zaslonka the bimetallic spiral with electric heating is used. The system is given in an initial condition if slowly to squeeze out an accelerator pedal one or two times. After engine start a food from the generator moves on a ceramic heater which quickly heats up. Heat is transferred to a bimetallic spiral via the plug; when the bimetallic spiral heats up, it is unwound, opening an air zaslonka.

Completely automatic air zaslonka

For adjustment of provision of an automatic air zaslonka the wax capsule is used. The capsule heats up cooling liquid of the engine. At low temperature of cooling liquid the wax capsule is completely compressed – the air zaslonka is closed. After start of the engine and during warming up heat from heating-up cooling liquid of the engine influences a wax capsule which starts to extend gradually; the expanding capsule gradually opens an air zaslonka. When the temperature of cooling liquid reaches a normal operating level, the air zaslonka will be completely open.

Both types

After engine start, the air zaslonka should be slightly opened a little for formation of less saturated fuel mix and prevention of a modulation of fuel at operation of the engine in a mode of idling and at poorly open butterfly valve. It is reached by use of depression of an inlet collector which influences a diaphragm; the connecting mechanism of a diaphragm opens an air zaslonka. On some models the second opening diaphragm is established. It is supervised by the thermovacuum valve and used in order that at engine temperature increase above a certain value the air zaslonka also opened more strongly.

The mode of fast idling joins by means of the gear cam connected to an axis of an air zaslonka through connecting draft. The lever of fast idling connected to the lever of a butterfly valve, presses on a gear cam. When the bimetallic spiral heats up and the air zaslonka opens, the lever falls on a cam teeth. Thus, speed of idling gradually decreases, while the cam of fast idling will not be free, and speed of idling will decrease to the normal. The screw of adjustment connected to the lever of fast idling, it is possible to use for adjustment of speed of fast idling.

If the butterfly valve is completely open, when engine temperature low, depression at a diaphragm of an air zaslonka will disappear that will lead to closing of an air zaslonka. It can cause a fuel modulation. For prevention of it, the mechanism of partial opening of an air zaslonka is used. When the butterfly valve completely opens, the lever of a butterfly valve falls a little to slightly open an air zaslonka down.