10.07.2023

What is an internal combustion engine block? Aluminum cylinder blocks: alloys. Possible number of cylinders in a block

The basis of a piston engine internal combustion is the cylinder block. The engine cylinder block is used on internal combustion engines with 2 or more cylinders. The cylinder block is made in the form of one solid cast part, which is intended for the following functions: it unites all the engine cylinders, is the basis for attachments (cylinder head, crankcase) and has places (beds) inside the structure for the crankshaft, channels for lubrication and cooling systems.

What is the cylinder block made of?

The most common material for making an engine block is cast iron. This is a traditional material. Next on the list is aluminum in the form of various alloys. The rarest material for a cylinder block is magnesium alloy.

Cast iron has such positive characteristics as rigidity and low sensitivity to engine overheating. Cylinder block, a device that works in constant shift temperature conditions, so the cast iron block is in the lead here. At the same time, there is a big disadvantage of a cast iron block - large mass.
Aluminum has such positive properties as excellent engine cooling and low weight. A special feature of aluminum blocks is the selection and installation of sleeves. The most common technology today is Locasil - pressing of aluminum-silicon sleeves and Nicasil - nickel coating. The disadvantage of the second technology is that it is not repairable. The Nikosil technology cylinder block is not subject to boring, but is replaced as an assembly. This is expensive for the car owner.
Magnesium alloy does not apply to conveyor production cylinder block due to its high cost. Although, it is an ideal combination of the rigidity and strength of cast iron and the lightness of aluminum.

Main components of the cylinder block

Cylinder head(cylinder head). It is attached to the top of the block using guide pins and cylinder head bolts. Between the cylinder head and the cylinder block there is a very important detail– cylinder block gasket.
Cylinder block gasket It can be asbestos-metal, non-asbestos or metal.
Engine cylinder– these are liners that are used in two versions: pressed directly into the cylinder block using an industrial method (usually for aluminum blocks); Removable sleeves: “wet” and “dry” types.
Carter. It is the structural lower part of the cylinder block. Performs the function of a housing for the crank mechanism (crank mechanism). The bottom of the crankcase is closed with an oil pan.

In the cylinder block body itself there are holes and channels for the engine lubrication and cooling systems. The cylinder block drain plug is designed to drain the coolant, while to drain the engine oil, there is a plug in the oil pan.

In the cavity of the cylinder block there are places to accommodate the camshaft drive. This area at the front is covered by the cylinder block cover. At the bottom of the block there are supports for the crankshaft main bearings. Good luck to you in understanding the secrets of the engine block design.

Civil engine building is a very conservative industry. All the same crankshaft, pistons, cylinders, valves as 100 years ago. Amazing crankless, axial and other schemes do not want to be implemented, proving their impracticality. Even the Wankel engine, the big breakthrough of the sixties, is essentially a thing of the past.

All modern “innovations”, if you look closely, are just the introduction of racing technologies from fifty years ago, seasoned with cheap-to-produce electronics for more precise control of the hardware. Progress in the construction of internal combustion engines is more likely in the synergy of small changes than in global breakthroughs.

And it seems like a sin to complain. This time we won’t talk about reliability and maintainability, but the power, cleanliness and efficiency of modern engines would seem like a true miracle to a person from the seventies. What if we rewind a few more decades?

A hundred years ago, engines were still carburetor, with magneto ignition, usually lower valve or even “automatic” intake valve... And we haven’t thought about any supercharging yet. And the old, old engines did not have a part that is now its main component - the cylinder block.

Before implementing the block

The first engines had a crankcase and a cylinder (or several cylinders), but they did not have a block. You will be surprised, but the basis of the structure - the crankcase - was often leaky, the pistons and connecting rods were open to all winds, and were lubricated from an oil can using the drip method. And the word “crankcase” itself is difficult to apply to a design that preserves the relative position of the crankshaft and cylinder in the form of openwork brackets.

For stationary and marine engines, a similar scheme remains to this day, but automobile internal combustion engines still needed greater tightness. Roads have always been a source of dust, which greatly harms machinery.

The pioneer in the field of “sealing” is considered to be the company De Dion-Bouton, which in 1896 launched a motor with a cylindrical closed crankcase, inside of which a crank mechanism was located.

True, the gas distribution mechanism with its cams and pushers was still located openly - this was done for the sake of better cooling and repairs. By the way, by 1900 this French company turned out to be largest producer cars and internal combustion engines in the world, producing 3,200 engines and 400 cars, so the design had a strong influence on the development of engine building.

...and then Henry Ford appears

The first mass-produced design with a solid cylinder block still remains one of the most mass-produced cars in history. Model Ford The T, introduced in 1908, had a four-cylinder engine, with a cast-iron cylinder head, foot valves, cast-iron pistons and a cylinder block - again cast iron. The engine volume was quite “adult” for those times, 2.9 liters, and the power was 20 hp. With. For a long time it was considered quite a worthy indicator.

More expensive and complex designs in those years sported separate cylinders and a crankcase to which they were attached. Cylinder heads were often individual, and the entire structure of the cylinder head and the cylinder itself was attached to the crankcase with studs. After the emergence of a trend toward larger components, the crankcase often remained a separate part, but blocks of two or three cylinders were still removable.

What is the point of separating the cylinders?

The design with separate removable cylinders looks a little unusual now, but before the Second World War, despite the innovations of Henry Ford, it was one of the most common schemes. In aircraft engines and air-cooled engines it has survived to this day. And the “boxer air” Porsche 911 series 993 did not have any cylinder block until 1998. So why separate the cylinders?

A cylinder in the form of a separate part is actually quite convenient. It can be made from steel or any other suitable material, such as bronze or cast iron. The inner surface can be coated with a layer of chromium or nickel-containing alloys, making it very hard if necessary. And on the outside, build up a developed jacket for air cooling. Mechanical processing of a relatively compact assembly will be accurate even on fairly simple machines, and with good fastening calculations, thermal deformations will be minimal. You can do galvanic surface treatment, since the part is small. If such a cylinder has wear or other damage, it can be removed from the engine crankcase and a new one installed.

There are also plenty of disadvantages. In addition to the higher price and high requirements for the build quality of engines with separate cylinders, a serious drawback is the low rigidity of such a design. Which means - increased loads and wear piston group. And combining the “separation principle” with water cooling is not very convenient.

Motors with separate cylinders left the mainstream a long time ago - the disadvantages outweighed them. By the mid-thirties, such designs were almost never seen in the automotive industry. A variety of combined designs - for example, with blocks of several cylinders, a common crankcase and a cylinder head - came across in small-scale luxury cars with displacement engines (you can remember the half-forgotten Delage brand), but by the end of the 30s it all died out.

Victory of all-iron construction

The design we are familiar with today has won thanks to its simplicity and low manufacturing cost. A large casting from a cheap and durable material after precise machining is still cheaper and more reliable than individual cylinders and careful assembly of the entire structure. And on lower valve engines the valves and camshaft are located right there in the block, which further simplifies the design.

The cooling system jacket was cast in the form of cavities in the block. For special occasions It was possible to use separate cylinder liners, but the engine on the Ford T did not have such delights. Cast iron pistons with steel compression rings worked directly against the cast iron cylinder. And by the way, the oil scraper ring in our usual form was not there; its role was played by the lower third compression ring, located below the piston pin.

This “all-cast iron” design has proven its reliability and manufacturability over many years of production. And it was adopted from Ford by such mass producers as GM for many years to come.

True, casting blocks with a large number of cylinders turned out to be a technologically difficult task, and many engines had two or three half-blocks with several cylinders in each. Thus, in-line “sixes” of the thirties sometimes had two three-cylinder semi-blocks, and in-line “eights” were even more so manufactured according to this design. For example, the most powerful Duesenberg Model J motor was made exactly this way: two half-blocks were covered with a single head.

However, by the beginning of the forties, progress made it possible to create solid blocks of this length. For example, the Chevrolet Straight-8 “Flathead” block was already solid, which reduced the load on the crankshaft.

Cast iron sleeves in a cast iron block were also a fairly good solution. High-strength alloyed chemical-resistant cast iron was more expensive than usual, and there was no point in casting an entire large block from it. But a relatively small “wet” or “dry” sleeve turned out to be a good option.

The fundamental design of motors, mastered in the pre-war years, has not changed for many decades in a row. Many cylinder blocks modern engines cast from gray cast iron, sometimes with high-strength inserts in the top dead center area. For example, a cast iron block has a completely modern Renault Captur with the F4R engine, the maintenance of which we are talking about. Cast iron is good, in particular, because a block made of it can easily be overhauled by boring cylinders of larger diameter. Unless, of course, the manufacturer produces “repair” size pistons.

True, over the years the blocks become more and more “openworked” and less massive. It’s difficult to find numbers for early blocks, but let’s take two families of motors with a difference of just over 10 years. For the GM Gen II series block of the mid-90s, the wall thickness of the motors ranged from 5 to 9 mm. The modern VW EA888 of the late 2000s already has from 3 to 5. But we are clearly getting ahead of ourselves...

Making the block lighter

Thinning the walls, which designers have been doing with all their might in recent years, is, as you understand, not the only way to reduce the weight of the block. In the 20-30s, they thought much less about saving weight and fuel than now, but the first attempts at lightening were made. And even then they thought of using aluminum.

On racing and sports cars of that era, one could find a symbiosis of an aluminum crankcase and cylinder head with cast iron cylinder blocks. Then progress in metalworking made it possible to create a more convenient version of such a symbiosis. The cylinder block remained solid, but was cast from aluminum, which reduced its weight by three to four times, including due to the better casting properties of the metal. The cylinders themselves were made in the form of cast iron sleeves, which were pressed into the block.

The cartridges were divided into “dry” and “wet”; the difference is generally clear from the name. In blocks with a dry sleeve, it was inserted into aluminum cylinder(or a block was cast around it) with an interference fit, and the “wet” sleeve was simply fixed in the block with its lower end, and when installing the cylinder head, the cavity around it turned into a cooling jacket. The second option turned out to be more promising at that time, since it simplified casting and reduced the mass of parts. But in the future, increasing requirements for structural rigidity, as well as the complexity of assembling such engines, left this technology “overboard” from progress.

Dry sleeves in an aluminum block are still the most common option for manufacturing parts. And one of the most successful, because the cast iron sleeve is made of high-quality alloy cast iron, the aluminum block is rigid and light. In addition, theoretically, this design is also repairable, like cast iron blocks. After all, a worn sleeve can be “taken out” and a new one pressed in.

What's next?

The only fundamentally new technology recent years- These are even lighter blocks with a super-strong and super-thin layer sprayed onto the inner surface of the cylinders. I have already written in detail about, and even about similar structures - there is no point in repeating myself. Conceptually, we have the same internal combustion engine of the 1930s. And there is every reason to believe that until the end of the “era of internal combustion,” when electric vehicles are brought to fruition, engines running on liquid hydrocarbons will remain approximately the same.

The cylinder block (BC) is the main element of any piston internal combustion engine. This block contains cylinder holes, inside which combustion of a mixture of fuel and air occurs. The result is the movement of the piston in the cylinder and the performance of useful mechanical work.

The cylinder block is the largest part. The remaining components of the engine, attachments and auxiliary mechanisms are mounted on the BC. These include the cylinder head, electric generator, air conditioning compressor, power steering, etc. A clutch is attached to the cylinder block for mechanical or robotic transmission, as well as the torque converter housing automatic transmission gear shift.

Today, the upper part of the cylinder block is covered by the cylinder head (), and the lower part of the BC is covered by the lubrication system pan. Previously, there were lower valve types of engines, when the elements installed today in the cylinder head (camshaft, valves and valve mechanism) were also located in the cylinder block, and the cylinder head itself was a simple cover with holes for installing spark plugs.

The material used to manufacture the cylinder block was gray alloy cast iron or aluminum alloys. The finished BC is obtained by casting and subsequent mechanical processing. The cylinders in the cylinder block can either be part of a casting or act as separate liners called “liners.” These cartridges can be “wet” or “dry”. This will directly depend on whether they have contact with the coolant in the engine cooling channels.

The cast iron cylinder block is noticeably stronger and more reliable, but has a higher specific gravity. An aluminum block is much lighter, but requires special strengthening of the load-bearing walls, lining the block by installing special liners made of alloy cast iron, coating the cylinder walls with wear-resistant metals using a special galvanic method, etc.

The cylinder block performs a number of additional functions, being the main part of the lubrication system and liquid cooling system for engines equipped with such systems. The fact is that the BC has special channels through which oil is supplied under pressure to the lubrication points, as well as cooling system channels through which the coolant circulates inside the cylinder block through peculiar cavities. The coolant circulation channels form a “cooling jacket”.

History of the creation of the cylinder block

Appearing at the end of the nineteenth century, the cylinder block went through a long evolution before remaining in the form in which it is used in the design of the vast majority of modern engines.

In order to put a six-cylinder engine under the hood of the small VW Golf, Volkswagen remembered the unpopular design of the VR6 cylinder block

The history of the appearance of the first in-line cylinder block is associated with the German inventor Nikolaus August Otto, who in 1876 invented the most efficient for its time

The V-block was invented in 1889 to build an improved four-stroke two-cylinder engine.

Engine block design

Cylinder blocks have different designs and configurations of varying degrees of complexity. The block can be in-line, with a sequential arrangement of cylinders, V-shaped with different cylinder camber angles, or even consisting of two V-shaped blocks, such as in the Bugatti Veyron EB 16.4. There are block designs with a cylinder camber angle of 180 degrees, for the so-called boxer engines, such as Subaru.

There are . In them, the cylinders are arranged in a checkerboard pattern, sequentially, but at the same time tilted in one of two directions, like a V-shaped engine. This synthesis of two varieties in one block makes it possible to improve its cooling and increase power in a small volume. This technology is used in modern engines Volkswagen company. Many owners Passat cars, Corrado, Golf, Vento, Jetta, Sharan do not even realize that they have a VR engine, since the block is covered with a common head and is arranged in such a way that the inclination of the cylinders is not noticeable.

The more cylinders in the block, the greater the weight of the engine. Therefore, the number of engine cylinders is a limited quantity

When casting, channels are provided in the cylinder block for coolant circulation and oil supply. The cylinder head is attached to the top of the cylinder block, and the oil pan is attached to the bottom. In addition, the cylinder block serves as the basis for connecting the gearbox and all attachments: generator, starter, carburetor, etc.

The described engine design with a separate block and head is the result of a long evolution. Previously, the block was assigned more functions and what is now in the block head was located in the block itself. In relatively recently produced engines, a camshaft was located in the block, and in earlier designs there was also a valve mechanism there. The cylinder head in the so-called one performed a simple role as a cover with holes for the spark plugs.

Possible number of cylinders in a block

The number of cylinders is a very important indicator of the engine and. Structurally, the increase in the number of cylinders is determined by the desire of engineers to increase engine power.

If you increase the engine power without increasing the number of cylinders, then it is necessary to increase the diameter of the pistons and make the engine cylinder block more massive, which leads to an increase in vehicle weight and an increase in fuel consumption. It turns out that by increasing engine power, we get a loss in mass, which means in dynamics, and we need to increase the power again. This is a typical vicious circle.

The Zaporozhets cylinder block housing is made of expensive aviation aluminum alloy

Engineers solved the problem of increasing power by increasing the number of cylinders in the engine block. At the same time, the pistons are reduced in diameter, which reduces friction losses, which means the engine power increases.

Cylinder block material

Today, cast iron, aluminum and magnesium cylinder blocks are manufactured with the addition of various alloys.

The choice of material is determined by its inherent properties. For example, a block made of cast iron is the most durable, more suitable for forcing, and less sensitive to overheating than others.

Magnesium alloy blocks combine the hardness of cast iron and the lightness of aluminum, but since magnesium is rare and expensive, it is used primarily for motorsports. Surprisingly, the ML-5 was made of aviation magnesium alloy, on which cast iron or aluminum cylinders were placed.

Aluminum blocks are lightweight and have good cooling ability, but require reinforcement of the cylinder walls. If you insert steel or cast iron pistons into an aluminum cylinder, the walls will wear out very quickly. It is also impossible to use aluminum for the manufacture of pistons, since they will immediately stick to the cylinder surface and the engine will jam.

The cylinder blocks of some BMW models cannot be overhauled because the inner walls of the cylinders are coated with a non-renewable composition - Nikasil

For these reasons, aluminum blocks at the first stage of their use were equipped with gray cast iron. However, loosely secured “wet” cast iron sleeves quickly broke the aluminum block, so it did not tolerate boost well and was sensitive to overheating.

The “wet” cartridges were replaced by thin-walled “dry” cartridges. This technology involves pressing thin-walled cast iron or composite liners into the body of the block, where they fit “like a glove.”

Alternative solutions

There are several alternative solutions for strengthening cylinder walls using latest technologies. This is a method of applying silicon crystals to the inner surface of a cylinder or, for example, using ready-made aluminum-silicon sleeves using Locasil technology from Kolbenschmidt.

Another technology involves applying a nickel coating to the aluminum cylinder walls with sputtering of silicon carbide crystals. The technology was mainly used in expensive engines sports cars, in particular, Formula 1 cars that are not subject to multiple overhauls.

Essentially, the engine cylinder block is the main body of the engine without its internals - the cylinder head, pistons, connecting rods, crankshaft, flywheel and other parts - just a single cylinder block.

Typical cylinder block of an 8-cylinder engine

Most engine blocks are made partly from aluminum and partly from cast iron, although in the late 1990s many experiments were carried out, and some motor blocks were even tried to be made from plastic. Such experimental materials were used in prototype cars in hopes of developing lighter, more efficient cars. The fact is that the cast iron cylinder block is quite large in size and makes up a significant part of the car’s weight. The cylinder block usually requires several people or special equipment to pick it up.

As you can see from the photo above, the cylinder block is not just a rectangular body - it is an alloy of complex shape with numerous holes (the largest of which are for the crankshaft and pistons), channels, recesses and protrusions. A series of channels and passages inside include a line and are designed to supply antifreeze from the radiator to all hot areas of the engine, preventing it from overheating. After the coolant has circulated throughout the engine, it is returned to the radiator to be cooled by the fan and sent back to the engine.

The core of the cylinder block of an internal combustion engine is always the cylinders. The number of cylinders determines the size and placement of the block, and most cars have between four and eight cylinders. There are three types of engine blocks depending on the location of the cylinders relative to each other:

in-line cylinder block;
V-shaped cylinder block;
opposed cylinder block.

Attached to the bottom of the block is the oil pan, which is essentially a reservoir for the engine's lubricating oil. Periodically, engine oil needs to be changed, and in this case the oil pan is emptied of old oil and then filled with new oil.

During normal operation The engine block becomes very hot and drivers should be careful when touching it.

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