Mazda 626

1991-1998 of release

Repair and operation of the car

Nikki 30/34 carburetor and heater of an inlet collector

Design

The Aisan carburetor installed on the Mazda cars is the two-chamber vertical carburetor with consecutive opening of throttles. Drive of a throttle of the secondary camera vacuum. Adjustment of the automatic air gate (if it is established) is carried out by a bimetallic spiral with electric heating or the temperature wax capsule heated 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 installed). 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 rice. Nikki 30/34 carburetor and heater of an inlet collector). The heater serves for prevention of frosting of the carburetor and for improvement of dispersion of fuel mix at warming up of the engine. The temperature switch serves for switching off of a heater when temperature of the engine reaches a certain level. The heater has positive temperature coefficient of resistance – at increase in temperature, heater resistance grows.

Technical characteristics

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

System of adjustment of temperature of the arriving air

The gate of the inlet channel of the air filter opens or closed depending on temperature in a motive compartment. Depression from an inlet collector arrives through a thin hose on a vacuum diaphragm which controls position of the gate in the channel of an intake 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 serves the bimetallic valve closing and opening the ventilating channel. When temperature in a motive compartment rises, the valve opens, passing air that leads to elimination of depression at a vacuum diaphragm.

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

Now mix of hot air and cold external air comes to the carburetor. When temperature in a motive compartment rises above about 30 °C, the bimetallic valve completely opens; the gate completely closes intake of hot air from a final collector. Already warm air from a motive compartment comes to the carburetor. Thus, air temperature, coming to the carburetor, is supported approximately constant irrespective of temperature of external air (or temperatures in a motive compartment).

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

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

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

Internal fuel and air valves

The dosing system

Fuel comes to the carburetor, passing through the small mesh filter. Fuel level in the float-operated camera is regulated by the needle valve or a plastic float.

The float-operated camera has the internal ventilating channel leaving to area behind the air filter.

System of idling and transitional system

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

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

Fuel interruption in supply valve

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

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

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

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

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

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

Fuel from a fuel well of the secondary camera comes 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 produced from an opening under a butterfly valve of the secondary camera. Work of system is controlled by an electronic control unit. The system is activated at decrease in frequency of turns of a bent shaft from 1500 – 2300 rpm. The electronic control unit obtains information from the switch on a butterfly valve and ignition coils, and on the basis of the obtained information defines when it is necessary to give tension on the electromagnetic valve.

Damper of a butterfly valve (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 the droplets of fuel which are 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 in content of not burned down hydrocarbons in exhaust gases. Also, on models with the automatic transmission or system of decrease in toxicity of exhausts sharp impoverishment of fuel mix can be the reason 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 the speed of operation of the engine, without leading to increase in 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 primary cameras

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

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

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

At turn of wheels the switch in system of hydrostrengthening of steering closes a chain of the electromagnetic valve of system of increase in frequency of rotation of a bent 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 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 compensator of system of idling at high temperature of the engine – some models

The temperature compensator of system of idling at high temperature of the engine is the device, sensitive to temperature, which is installed 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 state (during the long operation of the engine in the idling mode in hot weather, for example). When temperature in a motive compartment becomes too high, fuel in the float-operated camera extends, and its level rises that leads to formation of too saturated mix. The temperature compensator serves for giving of additional amount of air to avoid formation of the oversaturated mix.

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

Pump accelerator

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

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 camera of the pump forces the way to final canals of the pump via the final valve (with a small weight) and comes to the mixing camera through a pump spray. The inlet (ball) valve remains is closed in order that fuel did not get back to the float-operated camera.

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 float-operated camera in the camera of the pump via the final (ball) valve.

The main dosing system

The amount of the fuel produced in an air stream is controlled by the calibrated main fuel jet. Fuel comes through the main fuel jet to the basis of a vertical fuel well which is lowered by the lower end in fuel in the float-operated camera. 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 emulsified mix is produced through a spray in the diffuser of primary camera of the carburetor.

Enrichment of fuel mix at incomplete loading of the engine

The air channel goes from zadrosselny space to the concentrating camera. During the operation of the engine in the mode of idling and at small opening of a butterfly valve, depression from an inlet collector in the channel takes away a plunger from the valve of enrichment of 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 stronger, depression in an inlet collector decreases. The plunger comes back to a starting position under pressure of a spring and presses on the valve which opens the fuel channel. Fuel from the float-operated camera via the channel comes to the main fuel well; fuel level in a well increases that leads to formation of more saturated fuel mix.

Operation of the secondary camera of the carburetor

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

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

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

Mechanical air gate

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

Opening of the air gate

After start of the engine, the air gate has to 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 the air gate.

Automatic air gate

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

Semi-automatic air gate

For adjustment of position of the semi-automatic air gate the bimetallic spiral with electric heating is used. The system is brought to an initial state if slowly to squeeze out an accelerator pedal one or two times. After start of the engine the power supply from the generator moves on the 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 the air gate.

Completely automatic air gate

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

Both types

After start of the engine, the air gate has to be slightly opened a little for formation of less saturated fuel mix and prevention of a modulation of fuel during the operation of the engine in the 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 the air gate. On some models the second opening diaphragm is established. It is controlled by the thermal vacuum valve and used in order that at temperature increase of the engine above a certain value the air gate also opened stronger.

The mode of bystry idling joins by means of the gear cam connected to an axis of the air gate through connecting draft. The lever of bystry idling connected to the lever of a butterfly valve presses on a gear cam. When the bimetallic spiral heats up and the air gate opens, the lever falls on cam teeth. Thus, idling speed gradually decreases until the cam of bystry idling is free, and the speed of idling will decrease to normal. The adjustment screw connected to the lever of bystry idling can be used for adjustment of speed of bystry idling.

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