The principle of the switch. Where is the switchboard. What is a commutator in a car

Switches are industrial devices that can be located separately or be an integral part of some electronic system.

The principle of the switch is to select the desired electrical circuit and connect it to the input circuit.

Modern switches are single-, double- or multichannel and also have an emergency mode of operation. Multichannel provides greater reliability and stability of the system where the switch is connected. A photo of one of the devices of this type is presented below.

In auto and motor equipment, the switch is a kind of microcomputer that generates and applies a current pulse to the ignition coil (to a spark that ignites the fuel in the motor).

In computer networks, there are also switching devices, for example, ethernet. The principle of the ethernet switch is that when a packet arrives for a specific address, it finds its port and forwards the packet to that particular user. While other devices transmit information to all ports.

What is the switch intended for?

These devices are widely used in various industries, and are also installed on vehicles as redistributors, switches or switches.

The principle of the switch is the same as for electronic, electromechanical, and also electron beam devices.

The purpose of the switch is to control the currents of the ignition coil, relying on the signals of the synchronization sensor.

In the vehicle, the circuit where the switch is located performs the function of the tester of the ignition system nodes, automatically adjusts the ignition timing and much more during the switching of the fuel system from gasoline to gas.

A bit of history

In the ignition system of the first cars , the battery-ignition option was used, which functioned on the principle of self-induction. This scheme of work took root in the car for a very long time, until new elements were created. They made it possible to improve the device and at the same time preserve the very principle of the switch.

The next step in the development of this device was the creation of its electronic analog with the use of keys based on transistors for automatic control of the current that flows in the ignition coil. The functioning of the EMP remained, and with the keys, the load applied to the contact groups of the breaker was reduced, and the current that flowed through the coil winding was increased.

The introduction of this technical innovation gave the following results:

• The stability of the ignition unit was significantly improved;
• Managed to ensure its uninterrupted operation with increased engine speed at high speeds of movement;
• The compression ratio was increased .

Further in the structure of switches began to apply:

• Thyristor circuits;
• Transistor elements;
• Sensors without contact;
• Hybrid circuits.

The use of these parts in the switch nodes markedly increased the quality of the car and made it possible to avoid the use of battery ignition.

The fact that an electronic switch has been introduced into the vehicle control systems has made it possible to replace the contact breaker of voltage with a non-contact sensor over time. The first such device was the VAZ switch, the ignition of which is based on the use of a Hall sensor.

The next step was the creation of multi-channel devices, and then the installation of a separate system consisting of a switch and a coil, made on each candle. This gave its advantages:

• A more powerful spark developed;
• Managed to reduce, and then eliminate losses in the trambler;
• It was possible to achieve a stable stroke at idle;
• Markedly decreased fuel consumption;
• At low temperatures, engine start-up has improved.

Operation of the device

The principle of the switch is to quickly switch the circuit with the rotation sensors and control the currents in the ignition coil.

The fact is that the signals coming from the rotation sensors are weak, or analog and inconvenient to use. Therefore, for application in the control system, they need not only to form, but also amplify, and then transmit to the primary winding of the coil, which allows high-speed commutation.

Multichannel devices are capable of controlling and switching several coils of ignition.

Location

Structurally, the switch can be combined with the electronic engine control unit, with the control signals from it coming directly to the ignition coil.

If the design is such that the device is located separately, it can be installed:

• On the ignition distributor, as in VAZ;
• In the immediate vicinity of the ignition coil;
• Separately on the surface of the metal for the implementation of a heat sink, for example, on the wing or a partition under the hood, as in "Ford";
• Near the electronic control unit and more.

For example, the switch "Audi" is located under the windshield in the engine compartment in a casing of waterproof material. There are also connectors for diagnostic devices.

Types of switches

Of the variety of this type of devices for cars and motorcycles are the following:

• A device that has a high-voltage built-in generator - DC CDI;
• Switch that works only in the presence of an additional high voltage source - AC CDI;
• Coil-commutator.

Switches DC-type are the most applicable because of easy connection, they have only four contacts on the case: Hall sensor, minus, plus, ignition coil.

These devices have a wide range of models:

• Without the maximum speed limiter or with it;
• With the possibility to change the phases of the ignition advance;
• For various needs - the availability of additional contact groups.

The AC-type switches differ from the first ones in that they do not need a constant voltage presence, and they are somewhat more complicated to connect. They also have very small dimensions and, therefore, a simpler design. Because of this, they do not have a maximum speed limiter, which reduces the safety of the use of machinery.

Coil-switches are the most interesting, poorly studied and rarely seen species. They combine the ignition coil and the switching element, and also do not have a Hall sensor.

The principle of their action is to interrupt the current, which flows through a high-voltage transformer with a low-voltage winding-coil. The self-interruption is effected by the contact switch, which is activated by the ignition distributor shaft.

The system with a mechanical interrupter has the following drawbacks:

1. Because of the excessively high current flowing in the coil's primary winding, a spark is often produced in the breaker, which leads to damage to the contacts: they are melted and burned.
2. In the cold and wet season, contacts are subjected to electrochemical erosion.
3. High current in the contacts of the interrupter leads to the fact that the duration of the spark discharge is short-lived, this leads to poor fuel ignition and unstable engine operation at low rpm. Consequently, the cost of the enriched mixture is required.

Elimination of these shortcomings became possible with the advent of high-voltage high-power transistors and the creation of contactless electronic ignition systems.

Some drivers are trying to improve the technical characteristics of the vehicle by replacing the contact ignition system with a non-contact ignition system from the new model. This is expensive and time-consuming, because you want to change the ignition system completely and purchase an electronic switch. In addition, it is not always possible to find a new version of the ignition switching suitable for the old one.

Despite this, even if a simple switch is connected between the ignition coil and the contact breaker on a powerful transistor, it is possible to significantly improve the quality of the vehicle's ignition system:

• The contacts of the breaker will not be melted due to the reduction of the current;
• The duration of the charge of the spark will increase by about half, which will cause a better ignition of the fuel;
• The system can always be returned to the original version by a simple re-commutation of the wire in the event of a breakdown of the switch on the transistor.

Types of switches

There are the following types:

• Standard (stock);
• sport;
• With the possibility of changing the phases of the ignition advance.

The standard , also called stock, switch is mounted by the manufacturer, so it is calculated for the parameters of the equipment where the installation is made. This, in turn, gives assurance that the engine will work reliably, economically and for a long time. Often, such switches are equipped with speed limiters, which not only can save the life of the driver, but also preserve the durability of aggregates and equipment nodes.

The sports switch is designed to increase the upper limit of engine speed. It is installed instead of the standard driver's choice. But to make such a replacement should only specialists, since together with this device it is necessary to replace some more details. If you do not do this or do it clumsily, the nodes of the equipment will not work correctly until the engine soon breaks down.

In addition, even the professional replacement of a standard sports switch adds a significant risk of an accident if the vehicle is driven by an inexperienced driver. Therefore, it is necessary to perform such actions very cautiously, realizing the forthcoming risk, especially when installing such a switch on a scooter. Actually, caution is always needed.

The principle of the switch with a change in ignition timing is that it compensates for the missing power in those speed zones, where necessary, and aligns the curve of the torque curve. This provides a gain in overclocking compared to standard switches and a uniform dynamics of the engine at different speeds.

What are the malfunctions

Signs that the ignition system is malfunctioning or there is a malfunction are the following states:

• There is no spark on the candles, the engine does not start;
• The engine starts, but after a short time stalls;
• The operation of the car engine is malfunctioning, uneven and comes to normal when replacing with a spare serviceable switch.

Typically, electrical faults occur in the following types:

• Short circuit due to overloading of one or both primary coils of the ignition coil;
• Failure in the operation of the high-voltage system.

How to check work

In order to test the operation of the device, there are several popular methods. In particular, this requires:

• The simplest method at the initial stage is to replace the device with a known one and compare the result;
• Check whether the supply voltage is applied to the terminals of the device. There are two ways to do this: a voltmeter and a load;
• With the help of an oscillogram to check the correctness of the form of the input signal that is fed to the switch;
• By the same method check the shape of the output signal;
• If the instrument panel in the car is equipped with a voltmeter, the test can be performed visually, following its scale. To do this, the ignition is switched on, at this time the nominal value on the indicator should be approximately 12V, and the switch takes some time to absorb the voltage. After the ignition is turned on, the shooter stops for a short time, and then moves about a millimeter to the right and stops. Violation of this sequence indicates a failure in the operation of the switch;
• Also to check the operation of the ignition, you can use a control - a normal car - a light bulb. One of its contacts is connected to the load, and the second to the output of the coil, which is connected to the commutator terminal. If the switch is in good condition, when the ignition is switched on, the bulb will flash and brighten up with time;
• Also for ignition control, if the fault is not connected to the switch, you need to check the wires, pins and connectors, and inspect the Hall sensor.

It is important to remember that the switches used with generator sensors can not be used in systems that contain a Hall sensor. The same and vice versa.

How the switch is repaired

This device plays an important role in the car ignition system. The principle of the switch is such that when it fails to start the engine of the machine does not work.

However, repair in most cases is impossible, and the device is to be replaced, so it will not be superfluous to have the driver with him a spare serviceable device.

Scooter switchboard

As a rule, in Chinese and in most Japanese scooters, an ignition system based on capacitors is used. The function of the condenser is that after starting the motor, energy is accumulated in it, and when the necessary voltage is reached, the current flows through the thyristor into the coil, where it is converted into a force that exceeds the inlet 60-200 times, which leads to the start of the scooter engine.

A typical representative of a scooter device that contains a voltage-storing capacitor is the Honda Dio AF 34. The advantage of such devices is that the spark is always produced at the same power, which leads to stability in the engine start-up process.

But due to the fact that many scooters ignition system contain constructively in the general scheme of electricity supply, in case of its short circuit or overload the switch goes out of order first. Therefore, it makes sense when buying a scooter to pay attention to those models where the connection of the switch and the ignition unit is mounted by an independent electrical circuit. The risk of failure in this case will noticeably decrease.