How to understand the lawn mower two -stroke or four -stroke. The principle of lubrication

What is the difference between a two.stroke engine from a four.stroke. comparative analysis

What is the difference between a two.stroke engine from a four.stroke? The most noticeable difference. These are ignition modes of the combustible mixture, which can be immediately seen by sound. A two.stroke motor usually publishes a piercing and very loud hum, while a more calm purr is characterized by a quadruple.

In most cases, the difference also consists mainly of the purpose of the unit and its fuel efficiency. In two.stroke engines, the ignition occurs at each turnover of the crankshaft, so in terms of power they are twice as much as four.stroke, in which the mixture is ignited only through the turnover.

Four.stroke engines are more economical, but heavier and more expensive. They are usually installed on cars and special equipment, while on devices such as law mmores, scooters and light boats, more compact two.stroke models are more common. But a gasoline generator, for example, can be found both two.stroke and four.stroke. The scooter engine can also belong to any type. The principle of operation of these engines is mainly the same, the difference only in the method and effectiveness of energy transformation.

What is a tact?

Fuel processing in both varieties of engines is carried out through the consistent execution of four different processes, known as the tacts. The speed with which the engine passes through these beats is exactly what the two.stroke engine differs from the four.stroke.

The first tact is the injection. At the same time, the piston moves down the cylinder, and the inlet valve opens to let the air-fuel mixture into the combustion chamber. Next comes the click tact. During this tact, the inlet valve closes, and the piston moves up the cylinder up, squeezing the gases located there. The cliff of the working move begins when the mixture ignition occurs. In this case, the spark from the candle ignites compressed gases, which leads to an explosion, the energy of which pushes the piston down. The last tact is the release: the piston rises up the cylinder, and the exhaust valve opens, allowing the exhaust gases to leave the combustion chamber so that you can start the process again. The reciprocating movements of the piston rotate the crankshaft, the torque from which is transmitted to the working parts of the device. This is how the energy combustion energy is converted into progressive movement.

What is the difference between a two.stroke motor and a four.stroke?

A two.stroke engine, an internal combustion engine in which the working cycle is performed in one turn of the crankshaft, t. e. filling the cylinder with a combustible mixture (or air), compression and combustion, as well as expansion and release of gases occur in two piston moves.

Disadvantages of two.stroke engines: the disadvantage is the high thermal loading of the piston group that reduces the reliability of the engine, and the complexity of the purge.

Advantages of two.stroke engines: in two.stroke engines all working cycles (processes of intake of the fuel mixture, produced gases, purges) occur within one turnover of the crankshaft over two main tacts. Engines of this type do not have valves (as in four.stroke ICE), their role is played by a piston, which, when moving, closes intake, exhaust and purge windows. Therefore, they are more simple in the design.The power of the two.stroke engine with the same cylinder size and the shaft speed of the shaft theoretically twice as much as four.stroke due to a larger number of working cycles. However, the incomplete use of the piston for expansion, the worst exemption of the cylinder from residual gases and the costs of part of the produced power to purge lead to almost an increase in power by only 60 70%.

How Two Stroke Engines Work (How It Works. 2 Stroke)

The four.stroke engine, the internal combustion engine, the operation cycle of which consists of four tactes (piston moves) occurring over two revolutions of the crankshaft of the engine. At its first turnover, the inlet and compression are carried out. The inlet of the working mixture (in the carburetor engine, or engine with ignition from spark) or air (in diesel) occurs when the piston moves from the upper dead point (in. m. t.) to the lower dead point (n. m. t.). Compression of the working mixture or air is carried out when the piston moves from n. m. t. To c. m. t. With the second turn of the crankshaft, a working stroke is performed (the piston moves the same as when inlet) and the release (the piston moves the same as when compressed). The working stroke (combustion. expansion) is carried out under the action of pressure on the piston of fuel combustion products. Release. the last time; During it, the worked out combustion products are removed from the engine cylinder.

Disadvantages of four.stroke engines: all idle passages (inlet, compression, release) are made due to kinetic energy stained with crankshaft and related details during the working move during which the chemical energy of the fuel turns into the mechanical energy of the moving parts of the engine. Since combustion occurs in a share of sec, it is accompanied by a rapid increase in the load on the lid (head) of the cylinder, the piston and other engine parts. The presence of such a load inevitably leads to the need to increase the mass of moving parts (to increase strength), which in turn is accompanied by an increase in inertial loads on moving parts. Inferior in power of two.stroke.The insignificant disadvantages that are more than pay off the advantages, include work on adjusting the heat clearance of the valves and the time to accelerate the scooter from a place that is slightly larger than that of two.stroke mopeds.

Advantages of four-stroke engines:-economy of fuel consumption;.Dariness;.time service;.Cathetic engine operates quieter and more stable.

Unlike a two.stroke engine in which the crankshaft lubrication, crankshaft bearings, compression rings, piston, piston and cylinder fingers are carried out due to the addition of oil to fuel; The crankshaft of the four.flowing engine is located in an oil bath. Thanks to this, you do not need to mix gasoline with butter or add oil into a special tank (on models of two.stroke scooters with a separate lubricant).

Also on the mirror of the piston and walls of the muffler and the exhaust pipe, much less soil forms. In addition, in a 2-stroke engine, the fuel mixture is released into the exhaust pipe, which is explained by its design.

What is called the Tact in the ICE

Tact on ICE is the action that takes place inside the mechanism. Moving the piston in the upper or lower direction. these are the tacts. over, one beat. when the piston moves up, performing the appropriate work. The movement of the piston down, which returns from the force that occurs during the combustion of fuel, is called the working course.

The first beat from which the work of the motor begins is filling the cylinder with a fuel mixture. The next stage is the compression of the mixture in the engine. Then ignition occurs, and at the end of the removal of burned gases. These are four tacts that are performed in engines of a four.stroke type. The crankshaft in four.stroke units make two turns with one ignition of fuel.

Two.stroke engines function in two cycles. the transportation of the fuel mixture into the cylinder, followed by its ignition, and the abduction of exhaust gases from the cylinder. In two.stroke units, the crankshaft makes one revolution when burning one portion of the fuel mixture.

This is the main difference between the units under consideration from each other.

ICE of the 2nd and 4th-free type in the type of fuel are gasoline and diesel. To find out in detail what advantages and disadvantages are available in the 2nd and 4-clock engines in question, we consider their design and the principle of operation.

Two.stroke ICE of its design features and description of the principle of work

Most chainsaws and benzos are equipped with two.stroke type driven devices. Two tacts are the stage of compression of the fuel mixture and the work of the piston (when it goes down). To understand how the two.stroke engine differs from the four.stroke, we will initially consider the structure of the motor. The main details of the engine are a cylinder, a piston, a crankshaft and a connecting rod. A candle of ignition is responsible for burning fuel, and the transportation of the mixture and gases removes through inlet and exhaust channels. The design diagram of a two.stroke engine is displayed in the photo below.

A two.stroke type engine has a simplified structure, unlike a four.stroke. The principle of operation is simple, and begins with the fact that the piston is moved from the lower dead point to the upper. There are three holes in the walls of the cylinder. inlet, graduation and purge channel. The inlet is located lower than the exhaust, and the purge is between them, as shown in the photo above. The inlet and purge channel is connected to a crooked-shaped chamber. Further, a detailed description of the principle of ICE work.

Initially, the fuel from the carburetor is transported to the cshm chamber. Through the purge hole, a pre-set of fuel-air mixture is sucked from the cshm chamber. The supply of the mixture stops when the piston overlaps the hole of the purge channel. Further, the piston movement is overlapping the final channel. Part of the fuel-air mixture goes to the exhaust channel. After blocking the graduation channel, the process of compressing the combustible mixture begins. This mixture consists of gasoline, oil and air. When the piston of the upper dead point reaches, the mixture is ignited by creating a spark of spark plugs.

4 Stroke Engine Theory | Briggs & Stratton

At the moment when compressing is carried out at the top of the cylinder, a vacuum is created in the lower part of the KSHM camera. This vacuum allows you to suck the next portion of the fuel from the carburetor for the next ignition. Closed fuel into the chamber of a crooked-shaped mechanism simultaneously performs lubrication of crankshaft and connecting rod. That is why a special oil for a two.stroke engine is added to the combustible mixture. Two.stroke engines do not have an oil crankcase, which is one of their main differences from four.stroke. All these processes are performed in one tact.

Burned gases pushing the piston down, thereby the working move is carried out. When the exhaust hole opens, exhaust gases entering the channel in the muffler come into it. The piston descending down creates pressure in the cshm chamber. Due to this pressure, squeezing out the fuel-air mixture of TPS from the KSHM chamber to the purge channel. In the cylinder, the next portion of TPS is pushed out immediately when accessing access to the purge hole. When filling the working chamber of the cylinder by a portion of the fuel mixture, the simultaneous displacement of the remaining exhaust gases occurs. The second clock ends when the piston of the lower dead point reaches.

The visual process of the two.stroke engine is represented in an animated image below.

This type of ICE has its advantages and disadvantages that are described below. Knowing the structure and principle of operation of a two.stroke engine, we will deal with four.stroke engines.

The principle of operation of a 4-stroke engine

The four.stroke trimmer for the grass has a more complex design. Four processes are sequentially and cyclically carried out in the engine, as a result, torque is transmitted to the cutting element:

  • Inlet. The piston lowers, as a result, the input valve automatically opens, through it it is gasoline into the system. When a certain point is reached, the fuel supply is stopped.
  • Compression. The piston with the nozzles closed moves up, as a result of AI-92 compresses. When the maximum point is reached, the candle ignites the fuel.
  • Working move. The volume of warmed gases increases, pushing the piston down. With the explosion of the mixture, both nozzles remain closed.
  • Removing combustion products from the working chamber. The crankshaft rotation occurs with the simultaneous lift of the piston. The exhaust valve is opened for the removal of exhaust gases.

The full cycle is performed for two crankshaft revolutions. Among the good, but inexpensive trimmers that can qualitatively mow grass:

Comparison by basic criteria

To decide which trimmer for the grass to choose: four.stroke or two.stroke, you should compare the main parameters affecting performance, ease of use, simplicity of service, repair, other criteria that will help to understand which option is preferable to solve the tasks in a particular area.

Simplicity of design

In two.stroke trimmers, the filling procedure, devastation of the working system coincides with the compression, the expansion of the fuel mixture. At the same time, the place of stay of the piston is near the dead zone below. In the walls are installed inlet and exhaust valve-a gas-bearing-oil spread is supplied through them and removed through them. There is no gas distribution system in the two.stroke power unit, which simplifies the design, makes it easier than a four.stroke analogue.

Engine power

In a two.stroke model, one revolution of the crankshaft is one working piston. In four.stroke. two. Logically, a 2-trimmer for grass should be twice as powerful than version 4t. But in practice, with an equal amount of horsepower, the productivity coefficient will fluctuate only in the range of 1.5-1.7 times.

Fuel consumption

Due to the structural features of the engine, the mixture of gasoline and oil on two-stroke trimmers does not completely burn out-part of the exhaust valve is disappeared during exhaust gas removal. In four.stroke units, the fuel mixture is produced by 100%, so such a motor will be more energy efficient, more economical.

The lubrication of the engine

For the operation of a two-stroke engine, a special mixture of AI-92 and machine oil is required. Depending on the trimmer for grass, selected lubrication, fuel is prepared in a proportion of 1 to 25 or 1 to 50. When choosing a liquid, it is important to look at the marking. there should be a 2T inscription on the bottle, as well as the features of use. In the process, the mixture fills the crooked and piston chambers, providing uniform lubrication of the surface of the parts located inside. After practicing, excess oil is burned in the chamber with gasoline.

Owners of four-stroke engines do not need to pre-prepare the fuel mixture-gasoline and 4-Maslo are tucked into separate containers located on the trimmer housing for the grass. As a result, it takes less time to prepare a tool for work for work. The likelihood of a situation is also reduced when, due to an error associated with violation of the proportions, the motor will not be lubricated, which will lead to its increased wear, failure.

If a trimmer for grass is bought to work in quiet zones, where it is important that the noise level does not much attract the attention of neighbors. it is better to choose a four.stroke option. In this case, you can expect that the indicator will be lower by 15-30 dB, depending on the model.

Small repair of a two.stroke trimmer for grass can be performed independently at home. For example, a user who does not have a specialized education will easily replace filters, spark plugs, will adjust the carburetor. With a breakdown of a four-stroke engine, the tool will have to be carried to the service center-due to the complex design, repairing with your own hands can cause more serious malfunctions, even bring the unit to complete unusual.

Comparison of two.stroke and four.stroke engines

Garden gasoline aggregates greatly simplify life to the owners of suburban real estate. They are based on an internal combustion engine.

Motokos, chain saws, bushes can be equipped with both a two.stroke and four.stroke engine, on which power, performance, weight, maintenance of the entire unit will depend.

The clock cycle of the internal combustion engine is the piston stroke from one dead point to another. One beat corresponds to a 180-degree turn (half-turn) of the crankshaft. With a 4-stroke process, the working cycle is carried out for two turns of the shaft, with 2 strokes-in one.

understand, stroke, principle, lubrication

Two.stroke and four.stroke engines have significant differences.

In weight, two.stroke engines are easier than four.stroke. Four strokes weigh about 50% more, since more details are required for a complex design.

Due to the greater efficiency of 4 stroke engines are more powerful. But lighter two-stroke engines can have a greater relationship with weight and are considered practical because of a single-cylinder engine, while a four-stroke model requires several cylinders to ensure constant electricity production.

Four.stroke engines are more economical and provide good control of air intake and release cycles, which leads to cleaner work. With a two.stroke cycle, part of the fuel is consumed, t.to. It comes out during the intake and compression tact.

In 4 stroke engines, the engine oil is separated from the fuel and injected from a separate tank, as a result of which it gets better grease. In a two.stroke engine, the lubricant is mixed with fuel, which reduces its service life. But due to joint circulation of lubricating oil and fuel, two-stroke units can function in any conditions. Due to the fact that two-stroke engines burn oil and fuel, they form a dirty combustion product. A more dirty combustion leads to a greater wear of the engine system, which reduces the overall service life.

Technique with a two.stroke engine is cheaper. But the cost of use per hour will be higher due to additional costs for oil and low fuel efficiency. It is cheaper to purchase them, but they have a short service life.

TOP-5 four-stroke trimmers

We have made a rating of 4-stroke trimmers, which have many positive reviews.

Makita EBH341U

Powerful, low.school, high.quality materials. Calmly starts and works evenly at idle. Highly mows high grass and weeds, it is possible to install a bush. The upper location of the engine, straight rod, shoulder belt. The unloading vest includes, a knife with 4 teeth, a knife casing, a mounting key.

engine. gasoline, four.stroke;

Power. 1.40 l.With;

Weight. 7.1 kg.

Champion LMH5640 Wheel

Great trimmer for grass for uneven areas, assembly from the box in 10 minutes. Maneuverable, easy to control, high.quality plastic, covered with powder paint. Large capture width, fast fishing.

type. wheel trimmer for grass;

Speasing width. 60 cm;

engine. gasoline, four.stroke;

Power. 5 l.With;

Weight. 32.1 kg.

Makita EM4351UH

Powerful, low.noise, strong trimmer for grass. Anti.vibration system, unloading vest, carbine for fastening. A complete set of adjustments. Protective casing, 4 gear knife. Direct bar, trimmer fishing line, mounting tool.

Speasing width. 43 cm;

understand, stroke, principle, lubrication

engine. four.stroke gasoline;

Power. 2 l.With;

Weight. 8.6 kg.

STIHL FS 131

Productive semi.professional trimmer for grass. Light, excellent balancing, ergonomic belt with comfortable adjustments. Convenient adjustment of a two.handed handle without a tool, installing a brush cutter. Stihl engine, plastic deck and case. Trammer fishing line, knife, shoulder belt. Anti.vibration system.

Speasing width. 50 cm;

engine. gasoline, four.stroke;

Power. 1.90 l.With;

Weight. 5.8 kg.

Honda UMK 435 T Urt

Silent work without vibrations, volume of fuel tank 0.63 l. Thick twisted fishing line for a trimmer allows even a light shrub to mow. Correctly designed working part, Honda engine. Upper location of the motor, adjustable handle.

understand, stroke, principle, lubrication

Speasing width. 44 cm;

engine. gasoline, four.stroke;

Power. 1.35 l.With;

Weight. 7.51 kg.

Differences in oil

The cardinal difference between the lubrication of one and the second engine is that the oil for a two.stroke is diluted with gasoline and eventually burns together with the mixture. If we consider the four.stroke option, then it is avoided by all measures to enter the oil into chambers intended for combustion of fuel. The conclusion from this is that for a four.stroke unit, oil is used, which has a full spectrum of lubricating properties for a long time, and for the second it is important that the soot does not remain after the oil and it completely burned in total with fuel.

As a result, two.stroke and four.stroke engines are largely different, both in principle of operation and the features of use. Ask the questions in the Комментарии и мнения владельцев and share your opinion.

The principle of engine operation.

The totality of processes periodically repeating in a certain sequence, as a result of which the heat energy is converted into a mechanical one is called a closed working cycle. Namely, the engine is driven by a piston, which moves up and down in the cylinder, due to the fire of the mixture from gasoline and air. Gasoline engines use an electric spark to ignite the combustible mixture, from the combustion of which the pressure necessary to move the piston is created. This process occurs in vacuum and isolated in the cylinder block.

The working cycle, which includes the supply of gasoline and air, ignition of the combustible mixture, pushing out the exhaust gases, and is repeated thousands of times per minute. So for the turnover of the crankshaft at 360 ° or one turn, the piston must move from its highest point, the upper dead point (VMT), to its lower point, to the lower dead point (NMT), and then back to the HMT. For example, at 1000 revolutions per minute, the working cycle occurs 1000 times per minute.

On this principle, all internal combustion engines work, the difference between a 4-stroke and 2-stroke engines lies in the actions in which the supply, compression of fuel, exhaust gas.

How a two.stroke engine works?

The two.stroke engine does not use inlet and exhaust valves to supply a combustible mixture and withdraw spent gases from the combustion chamber. For a full.time cycle, that is, two tacts are performed in one course of the crankshaft.

Instead of valves, a two.stroke engine has an intake and exhaust channels. holes in the side of the cylinder, which coincide with the pre.calculated piston position, where the piston is used to close or open these channels.

The inlet channel is located just below the position of the VMT (upper dead point) and when the piston moves up from the NMT, this channel is open and the fuel mixture is supplied to the combustion chamber. When the piston passes by the intake channel, the side wall of the piston blocks the hole, and the spark plug lights the fuel. Compression occurs due to the movement of the piston to the VMT covering the inlet hole, in combination with the simultaneous combustion. Thus, the tact of compression and ignition occurs as a whole.

The graduation channel is located on the opposite side of the cylinder next to the VMT. When the piston approaches the lowest point (NMT), it passes through the exhaust channel by opening it, as a result of which burned gases come out.

Two.stroke engine work cycle.

Tact 1: The inlet and ignition of a combustible mixture piston moves upward, fuel and air are pumped into the combustion chamber and the sparkling candle gives a spark. This happens just before the piston reaches the VMT.

Tact 2: Compression and exhaust position of the VMT Piston blocks the inlet hole, sealing the combustion chamber, and as a result of ignition of the mixture, the temperature and pressure of the gases sharply increase. Under this action, the piston moves down to NMT. At the lowest point, the outlet is no longer closed with a piston, and the output gas exits the output.

How a four.stroke engine works?

The four.stroke engine shares each stage: the process of combustion and release into four separate steps or tact.

So that fuel can fall into the combustion chamber, immediately before the piston reaches the VMT, the inlet valve opens, which allows to supply the fuel-air mixture from the carburetor or fuel injection system. When enough fuel enters the combustion chamber, the valve is closed and the vacuum and sealing the cylinder are created. After the spark plug gives a spark that causes an ignition of the combustible mixture (explosion of the mixture), this makes the piston move down. Then the outlet valve opens, allowing the outgoing gases to go out. At this time, sealing is disturbed, which causes decompression in the cylinder, and the pulse of the crankshaft pushes the piston back to the upper position of the VMT, and the entire process begins again.

Four.stroke engine work cycle.

Tact 1: Inlet during the first tact, the piston begins the movement from the VMT and ends in the NMT, at this moment the injection valve is open and the piston retracts the fuel mixture into the cylinder by creating a vacuum.

Tact 2: The compression of the second beat begins in the NMT and ends in the VMT, that is, immediately after the combustible mixture in the cylinder, the piston rises, squeezing it, preparing to fire during the working course. Inlet and outlet valve at this stage are closed.

Tact 3: Inflammation at this moment the crankshaft completed a full revolution of 360 degrees and while the piston is in the VMT (end of the compression tact), compressed air and fuel ignites from the spark plug (in a gasoline engine) and then, under the influence of the force force, the piston makes a working stroke down to NMT and performs mechanical work to rotate the crankshaft.

Tact 4: The release after the burning of the combustible mixture The piston first lowers to the NMT and then rises to the VMT. Moving (piston) to the VMT pushes out of the cylinder, combustion products through the open exhaust valve.

Mechanical differences of the 2-stroke and 4-clock engines.

When considering, the differences in these engines go beyond the main process of combustion. The four.stroke engine has a valve in the cylinder head that operates independently of each other, and requiring special control to open and close exactly at the right time. In other words, a gas distribution mechanism, the operation of which is regulated mechanically using a timing or belt, which sets the distribution shaft, if there are more than one cylinder in the engine. Hydraulic lifts contribute to this, which use the pressure of motor oil to lift the valves.

The timing belt is driven by the crankshaft in the lower part of the engine and then the belt (circuit) drives the distribution shaft (gas distribution mechanism). When the shaft rotates, the fists are pressed to the rockers or valve pushers to open and close the valves. Distribution shafts work using valve curtains, which are directly in contact with the fist and valve.

The four.stroke engine has a completely tight cylinder, the valves open only on top, in the combustion chamber. Thus, the oil lubricating the engine does not fall into the combustion chamber. In a two.stroke engine, everything is different when the piston passes through the intake hole, the combustion chamber is open, which means that the oil freely enters the cylinder and mixes with the fuel. That is why, in two.stroke engines to lubricate the engine, another type of oil is used, which burns together with the fuel. Fuel mixing with butter is performed before pouring into the tank.

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