So, we got acquainted with the theoretical position on the influence of the ignition interval on the uniformity of work. Consider the traditional order of operation of the cylinders in engines with different cylinder arrangements.
· the order of operation of a 4-cylinder engine with a displacement of the crankshaft journals of 180 ° (interval between ignitions): 1-3-4-2 or 1-2-4-3;
· the order of operation of a 6-cylinder engine (in-line) with an interval between ignitions of 120 °: 1-5-3-6-2-4;
8-cylinder engine (V-shaped) with 90° ignition interval: 1-5-4-8-6-3-7-2
In all schemes of engine manufacturers. Cylinder firing order always starts with master cylinder #1.
Knowing how your car's engine cylinders work will no doubt be useful to you in order to control the ignition order when performing certain repairs when adjusting the ignition or repairing the cylinder head. Or, for example, for installing (replacing) high-voltage wires, and connecting them to candles and a distributor.
General information, working conditions of connecting rods The connecting rod serves as the connecting link between the piston and the crankshaft. Since the piston performs a rectilinear reciprocating motion, and the crankshaft is rotational, the connecting rod performs a complex movement and is subjected to the action of alternating, shock loads from gas forces and inertia forces.
The connecting rods of automobile mass-produced engines are made by hot stamping from medium-carbon steel grades: 40, 45, manganese 45G2, and in especially stressed engines from chromium-nickel 40XN, chromium-molybdenum improved ZOHMA and other high-quality alloy steels.
A general view of the connecting rod assembly with the piston and elements of its design are shown in fig. 1. The main elements of the connecting rod are: rod 4, top 14 and bottom 8 of the head. The connecting rod kit also includes: bearing bushing 13 of the upper head, liners 12 of the lower head, connecting rod bolts 7 with nuts 11 and cotter pins 10.
Rice. 1. Connecting rod and piston group assembled with a cylinder liner; connecting rod design elements:
1 - piston; 2 - cylinder sleeve; 3 - sealing rubber rings; 4 - connecting rod rod; 5 - locking ring; b - piston pin; 7 - connecting rod bolt; 8 - the lower head of the connecting rod; 9- cover of the lower head of the connecting rod; 10 - cotter pin; 11 - nut of the connecting rod bolt; 12 - liners of the lower head of the connecting rod; 13 - bushing of the upper head of the connecting rod; 14 - the upper head of the connecting rod
The connecting rod rod, subject to longitudinal bending, most often has an I-section, but sometimes cruciform, round, tubular and other profiles are used (Fig. 2). The most rational are I-beam rods, which have high rigidity with low weight. Cross-shaped profiles require more developed connecting rod heads, which leads to overweighting it. Round profiles have a simple geometry, but require high quality machining, since the presence of machining marks in them leads to an increase in local stress concentration and possible breakage of the connecting rod.
For mass automotive production, I-section rods are convenient and most acceptable. The cross-sectional area of the rod usually has a variable value, and the minimum section is at the top head 14, and the maximum - at the bottom head 8 (see Fig. 1). This provides the necessary smooth transition from the rod to the lower head and contributes to an increase in the overall rigidity of the connecting rod. For the same purpose and to reduce the size and weight of the connecting rods
Rice. 2. Connecting rod profiles: a) I-beam; b) cruciform; c) tubular; d) round
in high-speed automotive-type engines, both heads, as a rule, are forged in one piece with the rod.
The upper head usually has a shape close to cylindrical, but the features of its design in each case
Rice. 3. Upper connecting rod head
are selected depending on the methods of fixing the piston pin and its lubrication. If the piston pin is fixed in the piston head of the connecting rod, then it is made with a cut, as shown in Fig. 3, a. Under the action of the coupling bolt, the walls of the head are somewhat deformed and provide a tight tightening of the piston pin. In this case, the head does not work for wear and is made with a relatively small length, approximately equal to the width of the outer flange of the connecting rod. From the point of view of assembly and dismantling, side cuts are preferable, but their use leads to a certain increase in the size and weight of the head.
With other methods of fixing the piston pins, bushings made of tin bronze with a wall thickness of 0.8 to 2.5 mm are pressed into the upper head of the connecting rod as a bearing (see Fig. 3, b, c, d). Thin-walled bushings are made rolled from sheet bronze and machined to a given size of the piston pin after being pressed into the connecting rod head. Rolled bushings are used on all engines of GAZ, ZIL-130, MZMA, etc.
The connecting rod bushings are spray or pressure lubricated. Splash lubrication is widely used in automotive engines. With such a simple lubrication system, oil droplets enter the head through one or more large oil-trapping holes with wide chamfers at the inlet (see Fig. 3, b) or through a deep cut made by a cutter from the side opposite to the rod. Pressurized oil supply is used only in engines operating with an increased load on the piston pins. Oil is supplied from the common lubrication system through a channel drilled in the connecting rod rod (see Fig. 3, b), or through a special tube installed on the connecting rod rod. Pressure lubrication is used in YaMZ two- and four-stroke diesel engines.
YaMZ two-stroke diesel engines operating with jet cooling of the piston bottom have special nozzles on the upper connecting rod head for supplying and spraying oil (see Fig. 3, d). The small head of the connecting rod is provided here with two thick-walled cast bronze bushings, between which an annular channel is formed for supplying oil to the spray nozzle from the channel in the connecting rod rod. For a more uniform distribution of lubricating oil, spiral grooves are cut on the friction surfaces of the bushings, and oil is dispensed using a calibrated hole in plug 5, which is pressed into the channel of the connecting rod, as shown in Fig. 4b.
The lower heads of the connecting rods of automobile and tractor types are usually made detachable, with reinforcing bosses and stiffeners. A typical split head design is shown in fig. 1. Its main half is forged together with the rod 4, and the detachable half 9, called the lower head cover, or simply the connecting rod cover, is fastened to the main one with two connecting rod bolts 7. Sometimes the cover is fastened with four or even six bolts or studs. The hole in the large head of the connecting rod is processed in the assembled state with a cover (see Fig. 4), so it cannot be rearranged to another connecting rod or changed by 180 ° relative to the connecting rod with which it was paired before boring. To prevent possible confusion on the main half of the head and on the cover, serial numbers corresponding to the cylinder number are knocked out near the plane of their connector. When assembling the crank mechanism, it is necessary to monitor the correct setting of the connecting rods in place, strictly following the manufacturer's instructions.
Rice. 4. The bottom end of the connecting rod:
a) with a direct connector; b) with an oblique connector; 1 - half of the head, forged together with the rod 7; 2 - head cover; 3 - connecting rod bolt; 4 - triangular slots; 5 - sleeve with a calibrated hole; 6 - channel in the rod for supplying oil to the piston pin
For automotive-type engines with a characteristic joint casting of the cylinder and crankcase in one block and Esssche, in the presence of a block-crankcase casting of the engine core, it is desirable that the large connecting rod head freely passes through the cylinders and does not impede assembly and dismantling. When the dimensions of this head are developed so that it does not fit into the hole of the cylinder liner 2 (see Fig. 1), then the connecting rod assembly with piston 1 (see Fig. 1) can be freely installed in place only with the crankshaft removed, which creates extreme inconvenience during repair ( Sometimes a piston without sealing rings, but assembled with a connecting rod, can be pushed behind the mounted crankshaft and inserted into the cylinder from the crankcase side (or, conversely, removed from the cylinder through the crankcase), and then complete the assembly of the piston group and the connecting rod, spending all this unproductively a lot of time) . Therefore, the developed lower heads are made with an oblique connector, as is done in the YaMZ-236 diesel engine (see Fig. 4, b).
The plane of the oblique split of the head is usually placed at an angle of 45° to the longitudinal axis of the connecting rod rod (in some cases, a split angle of 30 or 60° is possible). The dimensions of such heads after removing the cover are sharply reduced. With an oblique connector, the covers are most often fastened with bolts that are screwed into the main
half head. Studs are rarely used for this purpose. Unlike normal connectors, performed at an angle of 90 ° to the axis of the rod of the connecting rod (see Fig. 4, a), oblique head connectors (see Fig. 4, b) allow you to somewhat unload the connecting rod bolts from tearing forces, and the resulting lateral forces are perceived by the cover flanges or triangular slots made on the mating surfaces of the head. At connectors (normal or oblique), as well as under the bearing planes of connecting rod bolts and nuts, the walls of the lower head are usually provided with reinforcing tides and thickenings.
In the heads of automobile connecting rods with a normal parting plane, in the vast majority of cases, the connecting rod bolts are at the same time adjusting bolts, accurately fixing the position of the cover relative to the connecting rod. Such bolts and holes for them in the head are machined with high cleanliness and precision, like dowel pins or bushings. Connecting rod bolts or studs are exclusively critical parts. Their breakage is associated with emergency consequences, therefore they are made of high-quality alloy steels with smooth transitions between structural elements and are subjected to heat treatment. Bolt rods are sometimes made with grooves at the transition points to the threaded part and near the heads. The grooves are made without undercuts with a diameter approximately equal to the inner diameter of the bolt thread (see Fig. 1 and 4).
Connecting rod bolts and nuts for them in ZIL-130 and some other automobile engines are made of 40XN chromium-nickel steel. Steel 40X, 35XMA and similar materials are also used for these purposes.
To prevent possible rotation of the connecting rod bolts when the nuts are tightened, their heads are made with a vertical cut, and in the area where the connecting rod crank head mates with the rod, platforms or recesses are milled with a vertical ledge that keeps the bolts from turning (see Fig. 1 and 4). In tractor and other engines, connecting rod bolts are sometimes fixed with special pins. In order to reduce the size and weight of the connecting rod head, the bolts are placed as close as possible to the holes for the liners. Even small recesses in the walls of the liners are allowed, designed for the passage of connecting rod bolts. The tightening of connecting rod bolts is strictly standardized and controlled using special torque wrenches. So, in the ZMZ-66, ZMZ-21 engines, the tightening torque is 6.8-7.5 kg m (≈68-75 n.m), in the ZIL-130 engine - 7-8 kg m (≈70-80 n-m), and in YaMZ engines - 16-18 kg m (≈160-180 n-m). After tightening, castle nuts are carefully cottered, and ordinary nuts (without slots for cotter pins) are fixed in some other way (special lock nuts stamped from thin sheet steel, lock washers, etc.).
Excessive tightening of connecting rod bolts or studs is unacceptable, as it can lead to dangerous stretching of their threads.
The lower heads of the connecting rods of automobile engines are usually supplied with plain bearings, for which alloys are used that have high antifriction properties and the necessary mechanical resistance. Only in rare cases, rolling bearings are used, and the connecting rod head itself and the shaft neck serve as the outer and inner races (rings) for their rollers. The head in these cases is made one-piece, and the crankshaft is made composite or collapsible. Since, along with a worn out roller bearing, it is sometimes necessary to replace the entire connecting rod and crank assembly, rolling bearings are widely used only in relatively cheap motorcycle-type engines.
Of the antifriction bearing alloys in internal combustion engines, babbits on a tin or lead base, aluminum high-tin alloys and lead bronze are most often used. On a tin basis in automobile engines, an alloy of B-83 babbit containing 83% tin is used. This is a high-quality, but rather expensive bearing alloy. The lead-based alloy SOS-6-6 is cheaper, containing 5-6% of antimony and tin, the rest is lead. It is also called low antimony alloy. It has good anti-friction and mechanical properties, is resistant to corrosion, runs in well and, in comparison with alloy B-83, contributes to less wear of the crankshaft journals. Alloy SOS-6-6 is used for most domestic carburetor engines (ZIL, MZMA, etc.). In engines with increased loads, connecting rod bearings use a high-tin aluminum alloy containing 20% tin, 1% copper, the rest is aluminum. Such an alloy is used, for example, for bearings of V-engines ZMZ-53, ZMZ-66, etc.
For connecting rod bearings of diesel engines operating with especially high loads, lead bronze Br.S-30 is used, containing 30% lead. As a bearing material, lead bronze has improved mechanical properties, but is relatively poorly run-in and susceptible to corrosion from acidic compounds that accumulate in the oil. When using lead bronze, the crankcase oil must therefore contain special additives that protect the bearings from destruction.
In older models of engines, the anti-friction alloy was poured directly over the base metal of the head, as they said "over the body." Filling over the body did not have a noticeable effect on the dimensions and weight of the head. It provided good heat removal from the connecting rod journal of the shaft, but since the thickness of the fill layer was more than 1 mm, during operation, along with wear, a noticeable shrinkage of the antifriction alloy affected, as a result of which the clearances in the bearings increased relatively quickly and knocks occurred. To eliminate or prevent bearing knocks, they had to be tightened periodically, i.e., to eliminate excessively large gaps by reducing the number of thin brass gaskets, which for this purpose (about 5 pieces) were placed in the connector of the lower head of the connecting rod.
The method of pouring over the body is not used in modern high-speed transport engines. Their lower heads are supplied with interchangeable interchangeable liners, the shape of which exactly corresponds to a cylinder consisting of two halves (half rings). The general view of the liners is shown in fig. 1. Two liners 12 placed in the head form its bearing. The liners have a steel, less often bronze, base, with a layer of antifriction alloy applied to it. There are thick-walled and thin-walled liners. The liners somewhat increase the dimensions and weight of the lower head of the connecting rod, especially thick-walled, having a wall thickness of more than 3-4 mm. Therefore, the latter are used only for relatively low-speed engines.
The connecting rods of high-speed automobile engines, as a rule, are equipped with thin-walled liners made of a steel tape 1.5-2.0 mm thick coated with an anti-friction alloy, the layer of which is only 0.2-0.4 mm. Such two-layer liners are called bimetallic. They are used on most domestic carburetor engines. At present, three-layer so-called thin-walled trimetallic liners have become widespread, in which a sublayer is first applied to the steel tape, and then an anti-friction alloy. Trimetallic liners 2 mm thick are used, for example, for connecting rods of the ZIL-130 engine. A copper-nickel sublayer coated with a low antimony alloy SOS-6-6 is applied to the steel tape of such liners. Three-layer liners are also used for diesel connecting rod bearings. A layer of lead bronze, the thickness of which is usually 0t3-0.7 mm, is covered with a thin layer of lead-tin alloy on top, which improves the running-in of the liners and protects them from corrosion. Three-layer liners allow higher specific pressures on bearings than bimetallic ones.
The sockets for the liners and the liners themselves are given a strictly cylindrical shape, and their surfaces are processed with high precision and cleanliness, ensuring complete interchangeability for this engine, which greatly simplifies repairs. Bearings with thin-walled liners do not need periodic tightening, as they have a small thickness of the anti-friction layer that does not shrink. They are installed without shims, and worn ones are replaced with a new set.
In order to obtain a secure fit of the liners and improve their contact with the walls of the connecting rod head, they are made so that when the connecting rod bolts are tightened, a small guaranteed tightness is provided. Thin-walled liners are kept from turning by a fixing mustache, which is bent at one of the edges of the liner. The fixing mustache enters a special slot groove milled in the wall of the head near the connector (see Fig. 4). Inserts with a wall thickness of 3 mm or thicker are fixed with pins (diesels V-2, YaMZ-204, etc.).
The connecting rod bearing shells of modern automobile engines are lubricated with oil supplied under pressure through a hole in the crank from the general engine lubrication system. To maintain pressure in the lubricating layer and increase its bearing capacity, the working surface of the connecting rod bearings is recommended to be made without oil distribution arc or longitudinal through grooves. The diametral clearance between the liners and the connecting rod journal of the shaft is usually 0 025-0.08 mm.
Two types of connecting rods are used in trunk internal combustion engines: single and articulated.
Single connecting rods, the design of which was discussed in detail above, have become widespread. They are applied in all inline engines and are widely used in two inline automotive engines. In the latter case, two conventional single connecting rods are installed next to each other on each crankshaft journal. As a result, one row of cylinders is displaced relative to the other along the axis of the shaft by an amount equal to the width of the lower connecting rod head. To reduce this displacement of the cylinders, the lower head is made with the smallest possible width, and sometimes the connecting rods are made with an asymmetric rod. So, in the V-shaped engines of the GAZ-53, GAZ-66 cars, the rods of the connecting rods are displaced relative to the axis of symmetry of the lower heads by 1 mm. The displacement of the axes of the cylinders of the left block relative to the right block is 24 mm in them.
The use of conventional single connecting rods in two-row engines leads to an increase in the length of the crankshaft journal and the overall length of the engine, but in general this design is the simplest and most cost-effective. The connecting rods have the same design, and the same working conditions are created for all engine cylinders. The connecting rods can also be completely unified with the connecting rods of single-row engines.
Articulated connecting rod assemblies represent a single structure consisting of two paired connecting rods. They are usually used in multi-row engines. According to the characteristic features of the structure, forked, or central, and structures with a trailed connecting rod are distinguished (Fig. 5).
Rice. 5. Articulated connecting rods: a) forked design, b) with trailed connecting rod
For forked connecting rods (see Fig. 5, a), sometimes used in two-row engines, the axes of the large heads coincide with the axis of the shaft neck, and therefore they are also called central. The large head of the main connecting rod 1 has a forked design; and the head of the auxiliary connecting rod 2 is installed in the fork of the main connecting rod. It is therefore called the inner, or middle, connecting rod. Both connecting rods have split lower heads and are supplied with liners 3 common to them, which are most often fixed from turning with pins located in the covers 4 of the fork head. For the liners fixed in this way, the inner surface in contact with the shaft journal is completely covered with an anti-friction alloy, and the outer surface is only in the middle part, i.e., in the area where the auxiliary connecting rod is located. If the liners are not fixed from turning, then their surfaces on both sides are completely covered with an anti-friction alloy. In this case, the liners wear more evenly.
The central connecting rods provide the same amount of piston stroke in all cylinders of a V-shaped engine, just like conventional single rods. However, their set is rather complicated in production, and the fork is not always able to give the desired rigidity.
Pull-rod designs are easier to manufacture and have reliable rigidity. An example of such a design is the V-2 diesel connecting rod assembly shown in Fig. 5 B. It consists of the main 1 and auxiliary trailed 3 connecting rods. The main connecting rod has an upper head and an I-rod of conventional design. Its lower head is equipped with thin-walled liners, filled with lead bronze, and is made with an oblique connector relative to the rod of the main connecting rod; otherwise, it cannot be arranged, since at an angle of 67 ° to the axis of the rod, two lugs 4 are placed on it, intended for attaching a trailed connecting rod 3. The cover of the main connecting rod is fastened with six studs 6 wrapped in the body of the connecting rod, and from possible turning they are fixed with pins 5.
Trailer connecting rod 3 has an I-section of the rod; both heads are one-piece, and since their working conditions are similar, they are equipped with bronze bearing bushings. The articulation of the trailer connecting rod with the main one is carried out with the help of a hollow pin 2, fixed in the lugs 4.
In designs of V-shaped engines with a trailed connecting rod, the latter is located relative to the rod of the main connecting rod to the right of the rotation of the shaft in order to reduce lateral pressure on the cylinder walls. If at the same time the angle between the axes of the holes in the eyes of the attachment of the trailer connecting rod and the main connecting rod rod is greater than the camber angle between the axes of the cylinders, then the piston stroke of the trailer connecting rod will be greater than the piston stroke of the main connecting rod.
This is explained by the fact that the lower head of the trailer connecting rod describes not a circle, like the head of the main connecting rod, but an ellipse, the major axis of which coincides with the direction of the axis of the cylinder, therefore, the piston of the trailer connecting rod has 5 > 2r, where 5 is the piston stroke, and r is the radius crank. For example, in a V-2 diesel engine, the cylinder axes are located at an angle of 60 °, and the axes of the holes in the lugs of the 4 fingers of the lower (large) head of the trailer connecting rod and the rod of the main connecting rod are at an angle of 67 °, as a result of which the difference in the piston stroke is 6 .7 mm.
Articulated connecting rods with trailers and especially with forked designs of crank preparations, due to their relative complexity, are very rarely used in two-row automobile engines. On the contrary, the use of trailer connecting rods in radial engines is a necessity. The large (lower) head of the main connecting rod in radial engines is one-piece.
When assembling automobile and other high-speed engines, connecting rods are selected from the conditions so that their set has a minimum difference in weight. So, in the engines of the Volga, GAZ-66 and a number of others, the upper and lower heads of the connecting rods are adjusted in weight with a deviation of ± 2 g, i.e. within 4 g (≈0.04 n). Consequently, the total difference in the weight of the connecting rods does not exceed 8 g (≈0.08 N). Excess metal is usually removed from the lug boss, connecting rod cap and top head. If the upper head does not have a special tide, the weight is adjusted by turning it on both sides, as, for example, in the ZMZ-21 engine.
The order of operation of the cylinders, this is the name of the sequence of alternation of cycles in different cylinders of the engine. The order of operation of the cylinders directly depends on the type of arrangement of the cylinders: in-line or V-shaped. In addition, the arrangement of the connecting rod journals of the crankshaft and camshaft cams affects the order of operation of the engine cylinders.
What happens in the cylinders
The action taking place inside the cylinder is scientifically called the working cycle. It consists of gas distribution phases.
The valve timing is the moment of the beginning of the opening and the end of the closing of the valves in degrees of rotation of the crankshaft relative to the dead points: TDC and BDC (respectively, the top and bottom dead points).
During one working cycle, one ignition of the air-fuel mixture occurs in the cylinder. The interval between ignitions in the cylinder directly affects the uniformity of the engine. The shorter the ignition interval, the more uniform the operation of the engine.
And this cycle is directly related to the number of cylinders. More cylinders means shorter ignition intervals.
The order of operation of the cylinders in different engines
So, we got acquainted with the theoretical position on the influence of the ignition interval on the uniformity of work. Consider the traditional order of operation of cylinders in engines with different schemes.
- operating order of a 4-cylinder engine with a 180 ° crankshaft journal offset (interval between ignitions): 1-3-4-2 or 1-2-4-3;
- operating procedure for a 6-cylinder engine (in-line) with an interval between ignitions of 120 °: 1-5-3-6-2-4;
- 8-cylinder engine (V-type) with 90° firing interval: 1-5-4-8-6-3-7-2
In most cases, an ordinary car owner does not need to understand the operation of the engine cylinders at all. However, this information is not needed until the motorist has a desire to independently or adjust the valves.
Such information will certainly be needed if it is necessary to connect high-voltage wires or pipelines in a diesel unit. In such cases, it is sometimes simply impossible to get to a service station, and knowledge about that is not always enough.
Theoretical part
The order of work is the sequence with which the cycles alternate in different cylinders of the power unit. This sequence depends on the following factors:
- number of cylinders;
- type of cylinder arrangement: V-shaped or in-line;
- structural features of the crankshaft and camshaft.
Engine duty cycle features
What happens inside the cylinder is called the engine's duty cycle, which consists of certain valve timing.
The gas distribution phase is the moment at which the opening begins and the closing of the valves ends. The valve timing is measured in degrees of rotation of the crankshaft in relation to the top and bottom dead centers (TDC and BDC).
During the operating cycle, a mixture of fuel and air ignites in the cylinder. The interval between ignitions in the cylinder has a direct effect on the uniformity of the engine. The engine runs as evenly as possible with the shortest ignition gap.
This cycle directly depends on the number of cylinders. The larger the number of cylinders, the shorter the ignition interval will be.
Different cars - different principle of operation
For different versions of the same type of motors, the cylinders can work differently. For example, you can take the ZMZ engine. The order of operation of the cylinders of the 402nd engine is as follows - 1-2-4-3. But for the 406 engine, it is 1-3-4-2.
It must be understood that one working cycle of a four-stroke engine is equal in duration to two revolutions of the crankshaft. If you use a degree measurement, then it is 720 °. For a two-stroke engine, it is 360°.
The shaft knees are located at a special angle, as a result of which the shaft is constantly under the force of the pistons. This angle is determined by the cycle time of the power unit and the number of cylinders.
- 4 cylinder engine with a 180-degree interval between ignitions: 1-2-4-3 or 1-3-4-2;
- 6 cylinder engine with an in-line arrangement of cylinders and a 120-degree interval between ignitions: 1-5-3-6-2-4;
- 8 cylinder engine(V-shaped, 90 degree fire interval: 1-5-4-8-6-3-7-2.
In each engine scheme, regardless of its manufacturer, the operation of the cylinders begins with the master cylinder, marked with the number 1.
This site site article is located in the section with which you can have a general idea of the various nodes of the entire car.
The order of operation of the cylinders in different engines is different, even with the same number of cylinders, the order of operation may be different. Consider the order in which serial internal combustion engines of various cylinder arrangements work and their design features. For the convenience of describing the operation of the cylinders, the countdown will be made from the first cylinder, the first cylinder is the one in front of the engine, the last, respectively, near the gearbox.
3 cylinder
In such engines, there are only 3 cylinders and the operation procedure is the simplest: 1-2-3
. Easy to remember and fast.
The layout of the cranks on the crankshaft is made in the form of an asterisk, they are located at an angle of 120 ° to each other. It is possible to apply the 1-3-2 scheme, but manufacturers did not begin to do this. So the only sequence in a three-cylinder engine is the 1-2-3 sequence. To balance the moments from the forces of inertia on such engines, a counterweight is used.
4 cylinder
There are both in-line and boxer four-cylinder engines, their crankshafts are made according to the same scheme, and the order of operation of the cylinders is different. This is due to the fact that the angle between the pairs of crankpins is 180 degrees, that is, the 1st and 4th journals are on opposite sides of the 2nd and 3rd journals.
1 and 4 necks on one side, 3 and 4 on the opposite side. In in-line engines, the order of operation of the cylinders is applied 1-3-4-2 - this is the most common scheme of work, this is how almost all cars work, from Zhiguli to Mercedes, gasoline and diesel. Cylinders with crankshaft journals located on opposite sides work in series in it. In this scheme, you can apply the sequence 1-2-4-3, that is, swap the cylinders, the necks of which are located on the same side. Used in 402 engines. But such a scheme is extremely rare, they will have a different sequence in the operation of the camshaft.
The boxer 4-cylinder engine has a different sequence: 1-4-2-3 or 1-3-2-4. The fact is that the pistons reach TDC at the same time, both on the one hand and on the other. Such engines are most often found on Subaru (they have almost all the opposites, except for some small cars for the domestic market).
5 cylinder
Five-cylinder engines were often used on Mercedes or AUDI, the complexity of such a crankshaft lies in the fact that all connecting rod journals do not have a plane of symmetry, and are rotated relative to each other by 72 ° (360/5 \u003d 72).
The order of operation of the cylinders of a 5-cylinder engine: 1-2-4-5-3
,
6 cylinder
According to the arrangement of cylinders, 6-cylinder engines are in-line, V-shaped and boxer. A 6-cylinder engine has many different cylinder sequence schemes, they depend on the type of block and the crankshaft used in it.
inline
Traditionally used by a company such as BMW and some other companies. The cranks are located at an angle of 120° to each other.
The order of work can be of three types:
1-5-3-6-2-4
1-4-2-6-3-5
1-3-5-6-4-2
V-shaped
The angle between the cylinders in such engines is 75 or 90 degrees, and the angle between the cranks is 30 and 60 degrees.
The sequence of operation of the cylinders of a 6-cylinder V-shaped engine can be as follows:
1-2-3-4-5-6
1-6-5-2-3-4
Opposite
6-cylinder boxers are found on Subaru cars, this is the traditional engine layout for the Japanese. The angle between the crankshaft cranks is 60 degrees.
Engine sequence: 1-4-5-2-3-6.
8 cylinder
In 8-cylinder engines, the cranks are installed at an angle of 90 degrees to each other, since there are 4 strokes in the engine, then 2 cylinders work simultaneously for each stroke, which affects the elasticity of the engine. 12-cylinder runs even softer.
In such engines, as a rule, the most popular uses the same sequence of cylinders: 1-5-6-3-4-2-7-8 .
But Ferrari used a different scheme - 1-5-3-7-4-8-2-6
In this segment, each manufacturer used only the sequence known to him.
10 cylinder
A 10-cylinder engine is not very popular, manufacturers rarely used such a number of cylinders. There are several options for ignition sequences.
1-10-9-4-3-6-5-8-7-2 - used on Dodge Viper V10
1-6-5-10-2-7-3-8-4-9 — BMW charged versions
12 cylinder
The most charged cars were equipped with 12-cylinder engines, for example, Ferrari, Lamborghini, or the more common Volkswagen W12 engines.
-+The order of operation of a 4, 6, 8 cylinder engine is simply about the complex
By and large, it is not at all necessary for us, ordinary motorists, to know the order of operation of the engine cylinders. Well, it works and works. Yes, it's hard to disagree with that. It is not necessary until the moment when you wish to set the ignition with your own hands or adjust the valve clearances.
And it will not be superfluous to know about the operation of the car engine cylinders when you need to connect high-voltage wires to candles, or high-pressure pipelines for a diesel engine. And if you start repairing the cylinder head?
Well, you must admit, it would be ridiculous to go to a car service in order to properly install the BB wires. And how do you go? If the engine troit.
What does the order of the engine cylinders mean?
The sequence with which the cycles of the same name alternate in different cylinders is called the order of operation of the cylinders. 
What determines the order of the cylinders? There are several factors, namely:
- arrangement of engine cylinders: single-row or V-shaped;
- number of cylinders;
- camshaft design;
- type and design of the crankshaft.
Engine duty cycle
The operating cycle of the engine consists of gas distribution phases. The sequence of these phases should be evenly distributed according to the force of impact on the crankshaft. It is in this case that the engine runs evenly. 
It is imperative that the cylinders operating in series must not be adjacent. For this, engine manufacturers are developing schemes for the operation of engine cylinders. But, in all schemes, the order of operation of the cylinders begins its countdown from the main cylinder No. 1.
For engines of the same type, but different modifications, the operation of the cylinders may differ. For example, the ZMZ engine.
The cylinder firing order of the 402 engine is 1-2-4-3, while the cylinder firing order of the 406 engine is 1-3-4-2.
If we delve into the theory of the engine, but so as not to get confused, we will see the following.
A full cycle of a 4-stroke engine takes two revolutions of the crankshaft. In degrees, this is equal to 72°. A 2-stroke engine has 360°. 
The shaft knees are displaced at a certain angle so that the shaft is under a constant force of the pistons. This angle directly depends on the number of cylinders and the engine cycle.
The order of operation of a 4-cylinder engine, single-row, the alternation of cycles occurs through 180 °, but the order of operation of the cylinders can be 1-3-4-2 (VAZ) or 1-2-4-3 (GAZ).
The order of operation of a 6-cylinder in-line engine is 1-5-3-6-2-4 (the interval between ignition is 120 °).
The order of operation of an 8-cylinder V-engine is 1-5-4-8-6-3-7-2 (90° ignition interval).
There is, for example, the order of operation of a 12-cylinder W-shaped engine: 1-3-5-2-4-6 are the left cylinder heads, and the right ones: 7-9-11-8-10-12
In order for you to understand this whole order of numbers, consider an example. For an 8-cylinder ZIL engine, the cylinder operation order is as follows: 1-5-4-2-6-3-7-8. The cranks are located at an angle of 90°.
That is, if a duty cycle occurs in cylinder 1, then after 90 degrees of crankshaft rotation, the duty cycle occurs in cylinder 5, and sequentially 4-2-6-3-7-8. In our case, one rotation of the crankshaft is equal to 4 strokes.
The conclusion naturally arises that an 8-cylinder engine runs smoother and more evenly than a 6-cylinder one.
Most likely, you will not need an in-depth knowledge of how your car's engine cylinders work. But it is necessary to have a general idea about it. And if you decide to repair, for example, the cylinder head, then this knowledge will not be superfluous.
Good luck in learning how your car's engine cylinders work.
