Gasoline generator design - what should we know about mobile power plants? Types of gasoline generators and diesel electric generators What is the difference between a transistor circuit for starting a gasoline generator

If we look at the structure of a gas generator, we can see that it consists of only two main elements: the engine and the generator. The whole difficulty of manufacturing a device lies in adjusting the characteristics of the interaction of the components. The quality of the supplied electricity is determined by two quantities - frequency and voltage. And while stabilizing the voltage value is quite simple, adjusting the frequency is fraught with significant difficulties.

Circuit diagram of an inexpensive gas generator

Principle of operation

In inexpensive industrial gas generators, frequency and voltage adjustment is performed in two stages. The first stage is mechanical. The principle of its operation is based on the fact that as the electrical load increases, the engine speed drops. The engine speed sensor is mechanically connected to the carburetor throttle valve, so any change in speed is compensated by adjusting the throttle position automatically. The second stage of adjustment is carried out electronically. The figure above shows the circuit diagram of a typical inexpensive gas generator.

The operating principle of electronic speed stabilization is based on the dependence of the capacitor resistance on the current frequency. The diagram shows a stabilizing winding (L3) loaded onto a capacitor (C1). When operating at rated load, the output voltage is 220 V with a frequency of 50 Hz. Since the frequency of the output voltage directly depends on the number of revolutions per second, a change in the rotation speed of the generator rotor causes an unambiguous change in the voltage frequency on all windings of the generator.

The resistance of a capacitor depends on the frequency of the applied voltage. The higher the frequency, the lower the resistance. As a result, the current through the stabilizing winding varies depending on the load on the generator. As the load decreases, the number of revolutions increases, respectively, the frequency increases and the resistance of the capacitor decreases. The current through the winding (L3) increases and its braking value on the generator rotor increases. Thus, the rotation speed is adjusted continuously and instantly while the generator is running.

Electrical stabilization operates over a small range of changes, so the main adjustment function is assigned to the mechanical regulator. Here the range of adjustments is much wider, but at the expense of reaction speed. The internal combustion engine has inertia, and the change in its speed is slightly delayed when adjusting the throttle valve (this characteristic of the engine is called throttle response). Sudden load surges can cause the control system to oscillate.

Such a regulation system is difficult to make on your own, and an electronic one requires modification of the generator. The advantage of such a control circuit is the production of sinusoidal voltage with minimal distortion of the signal shape.

More complex generators are made using inverter circuit with double conversion (Fig. below).

Inverter Gasoline Generator

The alternating voltage of the generator is supplied to the rectifier, and then to the transistor converter, the output of which is a stabilized voltage of the required value. The presence of a rectifier removes restrictions on the stability of the generator frequency, and the transistor converter generates voltages regardless of the load size. Disadvantage inverter generators is their high cost and distortion of the output voltage waveform.

Selecting elements for a gasoline generator

As already said, mechanical adjustment It is very difficult to do on your own. Electronic will require alteration of the generator.

Therefore, it makes sense to make a gas generator with your own hands using an inverter circuit, and use a converter from a source as a converter uninterruptible power supply.

The choice of equipment is influenced by the following factors:

engine power;
engine speed;
generator voltage;
generator current;
converter power.

Maximum power gasoline generator primarily depends on engine power. The following devices have the following power and speed ratings:

lawn mower (trimmer) – 0.5…2 kW, 8000…9000 rpm;
chainsaw – 1.5…3 kW, 9000…12000 rpm;
walk-behind tractor - 3...9 kW, 2000...3000 rpm.

The easiest way to create a gas generator with your own hands is on a generator from a car (Fig. below). Typical generator for passenger car is capable of producing an output voltage of 13...14 V at a load current of 80...100 A. A simple calculation will show that the power of such a generator is no more than 1.4 kW. Large values can be obtained using generators from trucks.

A car generator is well suited for creating a gas generator

Many trucks are equipped with 24 V generators.

The generator has the indicated characteristics at an average speed of 5000 rpm, which does not correspond to the normal speed of the listed engines. To equalize the values, you can use a belt drive with different pulley diameters (Fig. below). The number of revolutions on the driving and driven pulleys is inversely proportional to their diameters. But the transmitted power changes in the opposite way.

Belt drive with different pulley diameters

A gasoline generator made on an engine from a chainsaw or lawn mower requires a reduction gear to reduce the number of revolutions on the generator shaft by about half. The power transmitted by the engine to the generator pulley will also double accordingly. If you use an engine from a walk-behind tractor, an overdrive gear is required.

Use gear drives in homemade design is impractical, since the labor intensity of manufacturing the gearbox is high. A poorly designed gearbox greatly reduces the efficiency of the installation and serves as a source of additional noise.

Following required device– inverter voltage converter (Fig. below).

Inverter converter – uninterruptible power supply

When talking about the power of the engine and generator, the power of the converter was not mentioned. It is this that can become the weak point of a homemade gasoline generator. Powerful converters have enough high cost. Remaking a low-power converter can only be done by those who are very well versed in radio electronics and know the principle of operation of the device. The minimum alteration consists of replacing the rectifier elements (power diodes and filter capacitors), key transistors and the output transformer.

It is not advisable to disconnect the battery of the uninterruptible power supply. It is used to load the generator and is designed to smooth out voltage surges at its output. Most car generators produce too much voltage at low loads.

Design of a homemade gas generator

All structural elements must be secured to a rigid base. For the base, the easiest way is to make a frame from steel corners 50x50 mm. The frame must have mountings for the engine, generator, converter and gas tank.

To reduce vibrations, all elements must be secured through shock-absorbing pads made of thick rubber.

Calculation example for a gasoline generator

You need to calculate a homemade gas generator in each individual case based on the available parts. As an example, we can give the calculation for an engine from a chainsaw and a common generator from a VAZ 2110 5102.3771 car.

The engine has a power of 2 kW at 10,000 rpm. Generator 5102.3771 produces a voltage of 14 V with a current of up to 80 A at 5000 rpm. The generator power is 1120 W.

For getting required quantity revolutions on the generator shaft, a reduction gear with a gear ratio of 1:2 is required. If you leave its standard pulley with a diameter of 51 mm on the generator shaft, then a pulley with a diameter of 25 mm will need to be installed on the engine shaft. This is very little. The transmission belt will be severely bent and will be subject to heavy loads. It is better if the generator pulley is installed on the engine, and in its place put a pulley with a diameter of 100 mm. The pulley can be machined to lathe made of duralumin.

While the engine is running at a nominal speed of 10,000 rpm, the generator rotor will rotate at a frequency of 5,000 rpm, which is optimal value. In order to fully utilize the generator's power reserve, a converter with a power of at least 1.5 kW is required.

Video. Do-it-yourself gasoline generator.

Making a gas generator with your own hands only makes sense if you have most of the necessary components. Purchasing all the components will not make it possible to make a gasoline generator cheaper than a ready-made industrial one. It is also necessary to take into account the time spent and the risk of damage resulting from setup and adjustment.

Gasoline generator is a power plant with two-stroke or four-stroke gasoline engines, in which an asynchronous or synchronous generator alternating current. In case of frequent power outages, a self-made gas generator - perfect solution to maintain the flow of electricity.

A gas generator is no less necessary for industrial purposes, for example, when working with welding machine. The average operation of the device with a full tank of fuel can vary from 5 to 10 hours depending on the power output and fuel consumption.

Device and design

In private country houses, on summer cottages in villages you can very often observe a loss of electricity for several hours or even days in winter time of the year. An energy generator is an ideal option for maintaining efficiency household appliances in the house, but sometimes in severe winter an emergency can occur and your generator stops working.

This extremely unpleasant situation requires quick repair, but we have a separate article for it. Now we will analyze the design of the gas generator and its components.

The key element of the unit is the gasoline engine, which comes with different systems, such as: lubrication supply, noise reduction and fuel supply. An exhaust pipe leads outward from the engine to remove waste.

A fuel tank with a fuel level indicator is most often located above the engine. Located next to the engine and below the tank air filter and battery.

Gasoline generator design diagram

To keep the generator as quiet as possible, a muffler is installed on the exhaust pipe. Let us note right away that we will not make a muffler for a gas generator with our own hands, since this is very time-consuming and often unsafe.

The generator control panel contains a voltmeter, circuit breaker, generator readings (for more advanced models), ignition switch, sockets, output direct current and ground terminals. To make the generator easy to move, it is equipped with wheels and special stops that prevent free movement.

We assemble a gas generator on our own

Before making a gas generator with your own hands, I would like to give a brief educational program on the engine. For weak generators, a two-stroke engine is also suitable for short-term use. But if uninterrupted operation of a huge number of communication and household appliances in the house for more than 5 hours, you will have to get a four-stroke.

Generator made from a lawn mower:

The engine power determines the type of alternator: three-phase or single-phase. If a load of more than 5 kW is required, single-phase options will no longer be suitable.

So, to create a simple DIY version of a gasoline generator, you will need a gasoline engine, an inverter, and an alternator. In practice, engines from motorcycles, cars, chainsaws or lawn mowers are often used. Preferably buy or pick up car generator, since it already has a voltage regulator.

Very important!!! A powerful car generator, which is designed for powerful engines, may not work with a weak engine of a future design. If there is no other possibility, you need to reduce the current output by balancing the excitation coil.

As a voltage converter, you can purchase a regular UPS purchased for computers or various office equipment.

In addition to the main elements listed above, you will also need a do-it-yourself mount for a gasoline generator (you can take an unnecessary car tire) and a housing (you can make them from old household appliances or from several sheets of metal). Instead of fuel tank, for lack of ideal option, you can take a five-liter plastic bottle. Well, you'll have to spend money on a muffler.

Assembly steps

All elements of the future generator should be attached to separate parts tires. They must be firmly secured, since vibrations may occur when the generator is operating and the generator will fall apart without working even a day. The level is very loud noise is reduced by installing a muffler that inhibits the propagation of sound. You can make noise insulation for a gas generator with your own hands, but almost every mechanic will say that it’s not worth it, so this moment we'll miss out.

When using a lawn mower, the work is greatly simplified, since the installation can be assembled using the device cover as a basis. As an addition, you can make their plywood body with a removable side for structural repair and convenient maintenance.

You can understand and study the assembly of a gas generator with your own hands in more detail by watching the video:

Curiosity about “crazy hands” and a banal desire to save money motivates quite a large number of people to independently assemble an electricity generating unit. How feasible is this idea, and how long will an installation of this kind, made from “grassroots”, last?

How reliable is a homemade generator?

Some craftsmen who have been designing gas generators for many years boldly declare that such a device will last no less than one professionally assembled at a factory. Moreover, when self-assembly there are many advantages, namely:

Financial savings ( average cost a unit with a power of up to 1 kW will cost at least $120)
The pride and pleasure of self-assembly
Possibility to select the necessary generator parameters for personal needs
Knowledge of the device and the ability to disassemble the gas generator with your own hands for repairs

Another part of the people who are skeptical about homemade units, assures that the savings are not worth it, because:

If you buy all the elements for a gas generator, then the sum of all the elements separately will cost one and a half to two times more.
Selecting a generator for an engine and vice versa for a beginner is a very difficult and sometimes impossible task.
Manufacturing the unit requires certain knowledge in tools.
It may take a considerable amount of time to implement the plan.
Gas generators manufactured in factories have many advantages over homemade ones, namely: automatic switching on of the generator as a backup power when the main line is turned off, aesthetically beautiful appearance, self-diagnosis with tracking of operating parameters and operational errors.
Homemade devices are usually heavier and larger than factory models.

You can increase the operating time of the generator and reduce the chance of failure by adhering to the basic rules for operating the device, namely:

Before starting the gas generator, you should check that it is leak-tight and free of damage.
Structural elements should be firmly secured. Failure to fully tighten the nut during operation, especially during long-term operation, can lead to an accident.
It is necessary to periodically check the remaining amount of oil.
The device should be filled with gasoline good quality, since the engines themselves are very sensitive to low octane fuel levels.
Do not load the gas generator to more than 80 percent of its maximum capacity.
Don't forget to clean your engine filters regularly.
Allow the engine to warm up after starting. Connect the power supply in the house only 2-3 minutes after start.

Let's sum it up

A gasoline generator is an excellent unit for a backup or main source of power for a home. Wide choose models in stores will allow you to choose it based on your own needs and wishes, however, their cost is not always low enough to provide a compelling reason to buy it without hesitation.

Making a gas generator with your own hands will be acceptable when you already have most structural elements and it would be a pity to throw them away. If you are a skilled mechanic and it is not difficult for you to design your own gas generator, you can safely take up this business. However, if at least one of the points or one of the sentences in this article causes you confusion, we do not recommend starting assembly in order to avoid unforeseen situations.

You will need

- Power unit;
- Generation block;
- Electrical conversion and protection unit;
- Control unit and auxiliary systems.

Instructions

The operation of an electric gasoline generator is based on the combustion of hydrocarbon fuel to produce a sufficient amount of energy, which goes through a chain of transformations. The first element of this system is a carburetor internal combustion engine, in which the burned fuel-air mixture drives a crankshaft with a flywheel. Power units in portable generators vary from the simplest two-stroke engines with direct injection carburetor to four-stroke machines with electronic system control of all operating modes.

Rotation from the crankshaft is transmitted to the generator shaft, causing it to move. Like engines, they may differ in their design and principle of operation, but they are most popular electric cars brush or brushless type with independent current excitation primary winding. In them, at a sufficiently high rotation frequency of one group of windings inside another, a displacement of magnetic fluxes and a redistribution of charges occurs, due to which a potential of the required magnitude is formed at different poles. He's not yet alternating current, capable of powering household or industrial consumers, and therefore requires an additional circuit of electrical conversions.

Can form on the generator windings electricity of different nature, therefore an electrical modulation unit is included in the portable power station device. Depending on the model of the gas generator, it can be inverter or transformer. The main task of this element is to bring the voltage in the outgoing network to a value of 230 Volts at a frequency of 50 Hertz. The secondary functions of the power conversion system are the removal of interference and surge voltages, current leakage control, overload protection and short circuits.

In the most perfect devices blocks are applied electronic control and control over operating modes. They include an automatic power regulator, a control unit for the fuel supply system and forced cooling. Quite common elements of a gasoline generator are self-diagnostic units that monitor in real time all the operating parameters of the generating station: from the composition of the exhaust gases to fine-tuning the current characteristics in the outgoing networks. An automatic switching device can also be used, instantly starting the generator when the voltage in the main power supply network fails and performing all the necessary switching operations.

There is no need to look for the benefits of your own gas generator; they lie on the surface.

Garage owners summer cottages, private houses (provided that these objects have an unreliable power supply, or are not electrified at all) have long appreciated the benefits of backup power supply.

Even if you live in cottage village with normal power supply, possible emergency situations. Loss of energy for a long time will lead to spoilage of food in the refrigerator in the summer, and malfunction of the heating boiler in the winter.

Therefore, many homeowners purchase industrial generators, the cost of which cannot be called economical.

Another direction for mobile power plants is tourism, expeditions and performing work using power tools in autonomous mode.

This useful device It is not an overly complex device, so it is quite possible to assemble a gas generator with your own hands, including 220 V.

Of course main reason such a decision is the desire to save. If you purchase components for a mobile power station in a store, the cost of parts will exceed the savings on assembly.

Therefore, a homemade gas generator will become profitable only if it has shareware components.

The most expensive spare parts are: the drive (gasoline engine) and the electric motor, which will act as a generator. These are the ones that need to be selected from the “trash” available in the storerooms.

What power plant can be selected for a generator?

First of all - power. In mobile power plants, the following ratio is used: for every kilowatt of electricity generated (not in peak, but in normal mode), 2-3 l/s of engine is supplied.

Important! This proportion works with properly selected components and minimal losses. It should be remembered that even the most inexpensive generator from the Middle Kingdom was designed by engineers.

As a rule, gas generators are developed as a complex, that is, a generating element is developed for a specific motor. For homemade installation you should choose a coefficient of 2-4 l/s per 1 kilowatt of energy. Otherwise, at full load the engine will quickly fail.