In this article, we will consider existing types of gas distribution mechanisms. This information will be very useful to motorists, especially those who independently repair their cars. Well, or trying to repair them.

Each TRM is driven by crankshaft. Transmission of effort can be carried out by a belt, chain or gear. Each of these three types of timber has both its advantages and disadvantages.

Consider more detail Types of timing timid

1. The belt drive has a small noise during operation, but does not have sufficient strength and can break. The consequence of such a cliff is a curved valve. In addition, the weak belt tension leads to the possibility of its jump, and this is fraught with the displacement of the phases complicated by the launch. In addition, the shot down phases will give unstable work at idle, and the engine will not be able to work with full capacity.

2. The chain drive can also make the "crossroad", but the probability of it is greatly reduced due to a special tensioner, which has a more powerful chain drive than that of the belt. The chain is more reliable, but has some noise, so not all car manufacturers use it.

3. The gear type of timing massively was used for a long time, in those times when the camshaft was placed in the KVS block (lower engine). Such motors are now disaster now. From their advantages, you can note the cheapness of manufacture, ease of design, high reliability and practical eternal, not requiring a replacement mechanism. Of the minuses - low power, to increase which can be only an increase in volume and, accordingly, the size of the structure (for example, Dodge Viper with a volume of more than eight liters).

Camshaft

What is it and why? The camshaft serves to adjust the torque of the valves that fuel into the cylinders on the inlet, and the exhaust gases are removed on the release phase. On the distributional shaft For these purposes there are specially eccentrics. The operation of the camshaft is directly related to the work. crankshaft , and thanks to this, injection fuel is carried out at the most useful point - when the cylinder is located in its lower position (at the bottom of the dead point), i.e. Before the intake path.

The camshaft (one or more - it does not matter) can be located in the GBC, then the motor is called "Uppermal", and can be located in the block of cylinders, then the motor is called "Nizhneval". It was written above. We usually equip powerful American pickups, and some expensive cars with a giant engine volume, oddly enough. In such power units, the valves are powered by rods, reaching through the entire engine. These motors are slow and very inertial, actively consumed the oil. Niower engines - a dead-end branch of the development of motor-building.

Types of gas distribution mechanisms

Above, we considered the types of GD drives, and now it will be discussed precisely about the types of the gas distribution mechanism.

SOHC mechanism

The name literally denotes the "one upper distribution shaft". Previously, it was called simply "OHC".

Such an engine, as clearly from the title, contains one camshaft, located the head of the cylinder block. Such an engine can have both two and four valves in each cylinder. That is, contrary to various opinions, the SOHC motor can be sixteenhathic glove.

What are the strengths and weaknesses of such motors?

The engine functions relatively quietly. Silence is relative to a two-channel motor. Although the difference is not big.

Easy design. So, it is cheaper. This also applies to repair and maintenance.

But from the minuses (albeit very minor), we can note the weak ventilation of the motor equipped with two valves per cylinder. Because of this engine power drops.

The second minus is in all sixteenthlylated motors with one camshaft. Since the camshaft is one, then all 16 valves are powered by one camshaft, which increases the load on it and makes the entire system relatively fragile. In addition, due to the low corner, the cylinder phases are worse and ventilated.

DOHC mechanism

It looks like the system almost the same as SOHC, but is distinguished by the second camshaft installed next to the first. One camshaft is responsible for bringing the intake valves, the second, naturally, graduation. The system is not ideal, and has, of course, their shortcomings and advantages, their detailed description is beyond the scope of this article. Invented DOHC at the end of the last century, and after that did not change. It is worth noting that the second camshaft is significantly complicated and the design of such an engine is reduced.

But for that, such an engine consumes less fuel due to better filling of cylinders, after which almost all exhaust gases leave them. The emergence of such a mechanism has significantly increased the efficiency of the engine.



OHV mechanism

Above the text, this type of engines (lower) was already considered. Invented him at the beginning of the last century. The camshaft in it are located at the bottom - in the block, and the rocker is used to bring valves. Of the advantages of such an engine, you can select a simpler CHC device, which allows V-shaped bottom engines to reduce their dimensions. Repeat and cons: a small number of revolutions, large inertia, a small torque and a weak power, the impossibility of using four valves to the cylinder (with the exception of very expensive cars).

Summarize

The mechanisms described above are not an exhaustive list. Motors, which spinning more than 9 thousand revolutions, for example, do not use springs under the valve plates, and in such engines one camshaft is responsible for the opening of the valve, and the second is for closing, which allows the system to do not hang on the revolutions above 14 thousand. Basically, such a system is used on motorcycles with a capacity above 120 hp

Video about how the timing works and what it consists of:

Consequences of the timing belt cliff on Lada Priora:

Replacing the timing belt on the example of Ford Focus 2:

The location of this mechanism depends entirely on the design of the internal combustion engine, since in some models camshaft is placed at the bottom, at the base of the cylinder block, and in the other - at the top, right in the head of the cylinder block. At the moment, the upper arrangement of the camshaft is optimal, since this significantly simplifies service and repair access to it. The camshaft is directly connected to the crankshaft. They are connected between themselves with a chain or belt transmission by providing communication between the pulley on the shaft of the timing and an asterisk on the crankshaft. This is necessary because it is driven by crankshaft.

The distribution shaft is installed in the bearings, which in turn are securely fixed in the cylinder block. The axial backlash is not allowed due to the application in the design of the clamps. The axis of any camshaft has a cross-cutting channel inside through which the mechanism is lubricant. Behind this hole is closed with a plug.

Important elements are camshaft camshafts. In quantity, they correspond to the number of valves in the cylinders. It is these items that perform the main function of the GDM - regulation of the order of the cylinders.

On each valve there is a separate cam, which opens it through push to the pusher. Freeing the pusher, the cam allows you to straighten the spring that returns the valve into the closed state. The camshaft device assumes the presence of two cams for each cylinder - by number of valves.

It should be noted that the fuel pump and the oil pump dispenser is also carried out from the camshaft.

Principle of operation and camshaft

The camshaft is connected to the crankshaft using a chain or belt, which is skiing the camshaft pulley and the crankshaft asterisk. Rotational movements of the shaft in supports provide special sliding bearings, thanks to which the shaft acts on the valve that run the operation valves of the cylinders. This process occurs in accordance with the phases of the formation and distribution of gases, as well as the engine working cycle.

The installation of the phases of the distribution of gases occurs according to the installation labels, which are available on gears or pulleys. The correct installation ensures compliance with the sequence of the motion cycles of the engine.

The main part of the camshaft are cams. In this case, the number of cams, which is equipped with camshaft depends on the number of valves. The main purpose of the cams is the implementation of the phases of the phases of the gas formation process. Depending on the type of timing type, cams can interact with a rocker or pusher.

The cams are installed between the supporting cakes, two for each engine cylinder. The camshaft during work has to overcome the resistance of the springs of the valves, which serve as a return mechanism, leading the valve to the original (closed) position.

The useful engine power is consumed to overcome these efforts, so designers constantly think how to reduce power loss.

In order to reduce friction between the pusher and the cam, the pusher can be equipped with a special roller.

In addition, a special desmodromic mechanism has been developed, which implemented an expedited system.

The supports of the camshaft are equipped with covers, while the front cover is common. It has stubborn flanges that are connected to cervous shafts.

The camshaft is made in one of two ways - forging made of steel or cast iron.

Breakdown camshaft

There is quite a lot of reasons why the camshaft knock is woven into operation, which indicates the appearance of problems with it. Here are the most typical of them:

The camshaft requires proper care: replacement of seals, bearings and periodical defects.

1. wearing cams, which leads to the appearance of a knock immediately only when starting, and then all the time of the engine operation;
2. bearing wear;
3. mechanical breakage of one of the elements of the shaft;
4. problems with fuel supply control, due to which an asynchronism of the interaction of camshaft and cylinder valves arises;
5. deformation of the shaft leading to axial bias;
6. poor-quality engine oil, replete impurities;
7. lack of engine oil.

According to experts in the event of a lightweight camshaft, the car can ride not yet one month, but it leads to enhanced cylinder wear and other details. Therefore, when a problem is detected, it should be eliminated. The camshaft is the collapsible mechanism, so the repair is most often carried out by replacing it with all or only some elements, for example, bearings. Camering chamber from exhaust gases, it makes sense to start opening the inlet valve. What happens when using tuning camshaft.

The main characteristics of the camshaft

It is known that among the main characteristics of the camshaft, the designers of the forced engines often use the concept of duration of the opening. The fact is that it is this factor directly affects the engine power produced. So than the valves are open longer, the more powerful the unit. Thus, the maximum engine speed is obtained. For example, when the opening duration is greater than the standard indicator, the engine will be able to work out an additional maximum power that will be obtained from the unit operation at low revs. It is known that for racing cars, the maximum engine speed is a priority goal. As for classic machines, when they are developed, the power of engineers is aimed at torque at low revs and pickup.

An increase in power may also depend on an increase in the valve lifting, which can add maximum speed. On the one hand, additional speed will be obtained by the short duration of the valve opening. On the other hand, valve actuators have not such a simple mechanism. For example, at high speeds of the valve motion, the engine will not work out an additional maximum speed. In the relevant section of our site, you can find an article about the main features of the exhaust gas production system. Thus, with a low duration of the valve opening after a closed position, the valve remains less time to get to the starting position. After the duration becomes even less, which is mainly reflected on the production of additional power. The fact is that at this moment the valve springs are required, which will have as much effort as possible, which is considered impossible.

It is worth noting that today there is a notion of reliable and practical lifting valve. In this case, the lift value must be more than 12.7 millimeters, which will provide high speed of opening and closing valves. The duration of the tact is from 2,850 revolutions per minute. However, such indicators create a load on the valve mechanisms, which ultimately leads to a brief service of valve springs, rods of valves and camshaft camshafts. It is known that the shaft with high valve raising speeds operate without failure at first, for example, up to 20 thousand kilometers. Nevertheless, automakers today develop such motor systems, where the camshaft has the same indicators of the duration of the opening of the valves and their lifting, which significantly increases their service life.

In addition, the engine power is affected by such a factor as the opening and closing of the valves relative to the camshaft position. Thus, the distribution phases of the camshaft can be found in the table, which is attached to it. According to this data, you can learn about the angular positions of the camshaft at the time of opening and closing the valves. All data is usually taken at the time of rotation of the crankshaft before and after the upper and lower dead points, are indicated in degrees.

As for the duration of the opening of the valves, it calculates, according to the phases of the gas distribution, which are specified in the table. Usually in this case, you need to summarize the opening moment, the closing moment and add 1 800. All moments are indicated in degrees.

Now it is worth dealing with the ratio of the phases of the gas distribution and camshaft. In this case, we will imagine that one camshaft will be a, the other - V. It is known that both of these shafts have similar forms of intake and exhaust valves, as well as a similar duration of the opening of the valves, which is 2,700 revolutions. In this section of our site you can find the article Troit Engine: Causes and Remedy Methods. Typically, takierals are called constructions with one profile. Nevertheless there are some differences between these camshafts. For example, the shaft and cams are located so that the inlet opens in 270 to the top of the dead point, and closes at 630 after the bottom of the dead point.

As for the exhaust valve of the shaft A, it opens in 710 to the bottom of the dead point and closes 190 after the top of the dead point. That is, the gas distribution phases look as follows: 27-63-71 - 19. As for the shaft in, he traces another picture: 23 O67 - 75 -15. Question: how shafts A and B can affect the engine power? Answer: Shaft A will create an additional maximum power. Still it is worth noting that the engine will have characteristics worse, in addition, it will be traced a narrower power curve compared to Valla V. Immediately it is worth noting that such indicators do not affect the duration of opening and closing valves, since it As we noted above, the same. In fact, changes in the gas distribution phases are influenced in such a result, that is, in the corners located between the centers of the cams in each distribution shaft.

This angle is an angular displacement that occurs between intake and graduation cams. It is worth noting that in this case the data will be indicated in degrees of rotation of the camshaft, and not in degrees of the rotation of the crankshaft, which were indicated earlier. So, the overlapping of the valves depends mainly on the corner. For example, at the time of reducing the angle between the centers of the intake and exhaust valve valves will be overlapped. In addition, at the time of increasing the duration of the valve opening, their overlap is also rising.

"Engine gas distribution mechanism"

The purpose of the work: to study the appointment, the device, the principle of operation, the design of the gas distribution mechanism (timing) of the engine.

Progress:

Purpose and characteristic

The gas distribution is called the mechanism that performs the opening and closing of the inlet and exhaust valves of the engine.

The gas distribution mechanism (TRM) serves for a timely intake of a combustible mixture or air into the engine cylinders and the release of exhaust gas cylinders. Gas distribution mechanisms with upper valves are applied in car engines. The top arrangement of the valves allows to increase the degree of engine compression, improve filling cylinders of a combustible mixture or air and simplify engine maintenance in operation. Car engines may have gas distribution mechanisms of various types ( picture 1), which depends on the layout of the engine and, mainly on the mutual location of the crankshaft, camshaft and intake and exhaust valves. The number of distribution shafts depends on the type of engine.

For upper location The camshaft is installed in the cylinder head, where the valves are placed. The opening and closing of the valves is made directly from the camshaft through the pushers or valve drive levers. The camshaft drive is carried out from the crankshaft using a roller chain or a toothed belt.

The upper arrangement of the camshaft simplifies the engine design, reduces the mass and inertial forces of reciprocating moving parts of the mechanism and provides high reliability and silent operation at high speed of the engine crankshaft.

Chain and belt camshaft drives also provide silent operation of the gas distribution mechanism.

At the lower location, the camshaft is installed in the cylinder block next to the crankshaft. The opening and closing of the valves is made from the camshaft through the pushers of the rod and rocker. The camshaft drive is carried out with the help of gears from the crankshaft. At the lower arrangement of the camshaft, the design of the gas distribution mechanism and the engine is complicated. At the same time, the inertial forces of the return and progressively moving parts of the gas distribution mechanism increase. The number of camshafts in the gas distribution mechanism and the number of valves per cylinder depend on the type of engine. Thus, with a greater number of inlets and exhaust valves, the best filling of the cylinders of a combustible mixture and their cleaning from exhaust gases. As a result, the engine can develop high power and torque. With an odd number of valves on the cylinder, the number of intake valves per valve is greater than the graduation.

Design and work of the gas distribution mechanism

Gas distribution mechanisms regardless of the location of the camshaft in the engine include valve group, transmission details and distribution shafts with drive.

IN valve group Inlet and outlet valves, guide valve sleeves and valve springs with fastening parts.

Transfer details They are pushers, guide pusher sleeves, rods of pushers, rocker, and rod axis, valve actuator levers, adjusting washers and adjusting bolts. However, with the upper arrangement of the camshaft, the pushers, guide bushings and rods of the pushers, the rocker and the rocker axis are usually absent.

On the figure 2. A gas distribution mechanism of the engine with the upper valve arrangement is presented, with the upper arrangement of the camshaft with a chain drive and two valves per cylinder. It consists of a camshaft 14 with a housing 13 of bearings, camshaft drive, levers 11 of the valve drives, reference adjusting bolts 18 valves 1 and 22, guide sleeves 4, springs 7 and 8 valves with fastening parts.

Figure 2. - Gas distribution mechanism of a car with a chain drive

1, 22 - valves; 2 - head; 3 - rod; 4, 20 - sleeves; 5 - cap; 6 - washers; 7, 8, 17 - springs; 9 - plate; 10 - tear; 11 - lever; 12 - flange; 13 - case; 14 - distribution shaft; 15 - cervical; 16 - cam; 18 - bolt; 19 - Nut; 21 - plate; 23 - Ring; 24, 27, 28 - asterisks; 25 - chain; 26 - Soothing; 29 - finger; 30 - shoe; 31 - Tensioner

Camshaft Provides timely opening and closing of valves. The distribution shaft is a five-rode, cast from cast iron. It has support cervix 15 and cam 16 (intake and graduation). Inside the shaft passes the channel through which the oil is supplied from the middle support neck to other cervices and cams. The leading knob is attached to the front end of the shaft. The shaft is installed in a special housing 13 of bearings, cast from an aluminum alloy, which is fixed on the upper plane of the head of the cylinder block. From axial movements, the camshaft is fixed by a hard flange 12, which enters the groove of the front support cervical shaft and is attached to the end of the bearing housing.

Distribution Vala drive It is carried out through a spinal sprocket installed on it 24 by a two-row roller chain 25 from the leading sprocket 28 of the crankshaft. This chain also rotates asterisk 27 shaft of the oil pump drive. The camshaft drive has a semi-automatic tensioning mechanism consisting of a shoe and a tensioning device. The chain is tensioned by a shoe 30, on which the springs of the tensioner device 31 are affected. Singing agent 26 is used to quench the oscillations of the leading chain branch. The shoe and the sedator have a steel frame with a susceptible layer of rubber. Restricted finger 29 prevents the chain decontamination when removing the driven sprocket of the camshaft.

Valves Open and closed intake and outlet channels. The valves are installed in the cylinder head in one row at an angle to the vertical axis of the engine cylinders. Inlet valve 1 For better filling of cylinders, the combustible mixture has a larger diameter head than the exhaust valve. It is made of special chromium steel with high wear resistance and thermal conductivity. Exhaust valve 22 works in more severe temperature conditions than intake. It is made composite. Its head is made of heat-resistant chromium steel, and the rod is made of special chromium steel.

Each valve consists of a head 2 and a rod 3. The head has a conical surface (chamfer), which the valve when closing tightly adjacent to the saddle from a special cast iron installed in the cylinder head and also having a conical surface.

The valve rod moves in the cast-iron guide sleeve 4, pressed and fixed by the locking ring 23 in the cylinder head, providing an accurate fitting of the valve. On the sleeve is put on an oil reflective cap 5 of oil resistant rubber. The valve has two cylindrical springs: outer 8 and inner 7. Springs are mounted on the valve rod using washers 6, plates 9 and a split crumple 10. The valve is activated from the camshaft fist with steel forged lever 11, which is based on one end to the adjusting bolt 18 And the other is on the valve terminal. The adjusting bolt has a spherical head. It is screwed into the threaded sleeve 20, fixed in the head of the cylinder block and the stroopable plate 21, and is fixed with a nut 19. The adjustable bolt is set by the required gap between the camshaft cam and the valve drive lever, equal to 0.15 mm on a cold engine and 0.2 mm on Hot Engine (heated to 75 ... 85 ° C). Spring 17 creates constant contact between the end of the drive lever and the valve terminal.

What is the distributional shaft (camshaft)? Distributional tree

What is camshaft in the car

The camshaft is a functional element of the car's fuel system, responsible for the correct sequential opening and closing of the motor valves. From the correctness of its functioning depend on fuel consumption, developed power, stability of its work, other driving characteristics. Let's look at what kind of camshaft in the car is its principle of operation and how incorrect work affects the car.

What is camshaft

What a camshaft looks like.

The camshaft is a rod on which several so-called cams are located. These are the details of the wrong shape rotating on the axis of the shaft. They correspond to the number of inlets of cylinders and are located exactly opposite them. The cam set is selected so that rotation guarantees stable and uniform combustion of fuel in the cylinders. And the work of the entire camshaft is clearly synchronized with other engine mechanisms.

On both sides of the cams on the shaft, support cervies, holding it in bearings. One of the most important nodes of the shaft are oil canals. The physical wear of parts, the power characteristics of the motor and the stability of its work depends on their condition. For the supply of oil in the axis camshaft, a through hole was made with outputs to support bearings and cams.

How the camshaft is arranged

The camshafts in the cylinder head.

The camshaft is the key functional component of the gas distribution mechanism, which determines the order of opening the valves to start the air-fuel mixture inside the cylinders. The synchronous operation of this mechanism provides continuous alternate combustion of fuel portions in the engine chambers. In some models of cars, the gas distribution mechanism has several camshafts.

The design, location, composition and characteristics of the camshaft camshaft are completely dependent on the engine model. In some machines, the camshaft is placed in the head of the cylinder block, and in others - in its base. The upper arrangement is currently considered optimal, as it facilitates repair and maintenance. The camshaft of the belt or chain transmission binds to the engine crankshaft, because it is exactly what is driven.

How the camshaft works

How the camshaft works.

With cross-consideration, the cam has a drop shape. When rotating, the elongated part of the cam is put on the valve pusher and leads to opening the valve. This provokes the supply of an air-fuel mixture for burning. With further rotation, the cam "releases" the pusher, and that under the action of the spring mechanism returns the valve to the closed position.

In the gear of the camshaft is twice as long as the crankshaft. This is due to the fact that in one working cycles of the engine crankshaft performs 2 turns, and camshaft - 1.

Engine configuration may include two camshafts. The layout of the gas distribution mechanism with one shaft is used in budgetary machines, where the cylinders have 1 pair of valves. Two camshafts are needed in models with two pairs of valves on the cylinders.

What is the camshaft sensor

The sensor position of the camshaft defines the angular positions of the timing transition relative to the crankshaft and generates the corresponding signals in the electronic motor control system. As a result, ignition and fuel injection are corrected. On gasoline cars, a failure in the operation of this device blocks the work of the ECU and does not allow you to start the motor. In diesel models, the launch is possible, but still complicated.

Like the crankshaft sensor, the camshaft sensor works on the basis of the HALL principle - the magnetic field in the device changes when the magnetic clearance is closed by a special teeth, which is on the shaft or the specifying disk. When the prong runs next to the sensor, a signal is generated sent to the electronic control unit. The frequency of pulses is directly related to the pace of rotation of the camshaft, based on which the ECU and makes adjustments to the operation of the engine. Due to the constant receipt of data on the position of the first cylinder piston, a sequential and timely injection is provided.

Breakdowns and their causes

A faulty camshafts most often produces its condition with a characteristic knock, which occurs due to wear of bearings or cams, shaft deformation, mechanical breakage of one of the elements. Such breakdowns arise as because of the factory marriage and as a result of natural wear.

The camshaft knuckle also occurs when using poor engine oil or due to non-regulated fuel supply. Because of this, the cylinder and cam flaps work inconschor - the engine loses power, consumes too much fuel and is unstable.

Video on the topic

Avtonov.com.

Everything about camshaft (distributional shaft) »AvtoVator

Good day, dear car enthusiasts! Let us try to decompose on the shelves together, in the literal sense of the word, the device of one of the important components of the gas distribution mechanism (timing) of the engine is a camshaft.

Device camshaft

The camshaft performs far from the last function in the operation of the car engine - it synchronizes the inlet and the release of the engine work clocks.

Depending on the type of engine, the timing can be with the lower position of the valves (in the cylinder block) and with the upper position of the valves (in the head of the cylinder block).

In modern engine building, preference is given to the top arrangement of the timing. This allows you to simplify the process of maintenance, adjustment and repair of camshaft, due to the simplicity of access to the MRM items.

Constructively camshaft is associated with the engine crankshaft. This compound is carried out by means of a belt or chain. The strap or chain of camshaft is hoping for the camshaft pulley and the star of the crankshaft. The camshaft drive is carried out at the expense of the crankshaft.

The most effective is considered a camshaft pulley - a split gear, which is used for tuning Rapurval in order to increase the power characteristics of the engine.

Bearings are located on the head of the cylinder head, which rotate the cervical cervix. In the case of repair for fastening the support necks, the camshaft repair liners are used.

Axial flavor camshaft prevent camshaft fixtures. Through the axis of the camshaft is performed through a hole. Through it, lubricant of the rubber surfaces of the details is carried out. From the back, this hole closes the camshaft plug.

Camshaft camshafts - the most important component. Their amount corresponds to the number of inlet and exhaust valves of the engine. It is the cams and perform the main purpose of the camshaft - adjustment of the phases of the engine gas distribution and the operating order of cylinders.

Each valve has its own, individual cam, which opens it, "running" to the pusher. When the cam comers from the pusher, the valve closes under the action of a powerful return spring.

The camshaft cams are located between the support cakes. Two cams: inlet and graduation per cylinder. In addition, the gear is mounted on the shaft to drive the distributor and oil pump. Plus Eccentric to actuate the fuel pump.

The gas distribution phase of the camshaft is selected by experienced, and depends on the design of intake and exhaust valves and the number of engine speed. Manufacturers for each engine model indicate the camshaft phases in the form of charts or tables.

The camshaft cover is installed on the camshaft supports. The front cover of the camshaft is common. It has a stubborn flanges that are included in the grooves in the cervical cakes.

The main details of the GRM

• Valves: intake and graduation. The valve consists of a rod and a plate plane. Valve saddles are inserted for simplicity of their replacement. Head inlet valve in diameter larger than graduation.
• The rocker serves to transfer the valve from the bar. In the short arm of the rocker, there is a screw for adjusting the thermal gap.
• The rod is designed to transmit effort from the pusher to the rocker. One end of the rod rests in the pusher, and the other in the adjusting bolt of the rocker.

Principle of operation of the camshaft

The camshaft is in the collapse of the cylinder block. Using a toothed or chain transmission camshaft is activated from the crankshaft.

The rotation of the camshaft ensures the effect of cams for the operation of intake and exhaust valves. This occurs in strict accordance with the phases of gas distribution and the order of operation of the engine cylinders.

For the correct installation of the phases of the gas distribution, there are installation labels located on the distribution gears or on the drive pulley. With the same purpose, crankshaft crankshafts and camshaft camshaft should be in a strictly defined position, relative to each other.

Thanks to the settings made by labels, the clock alternation is observed - the order of engine cylinders. The order of the cylinders depends on their location and the design features of the crankshaft and camshaft.

Engine working cycle

The period when the intake and exhaust valve in each cylinder should open once - this is the engine working cycle. It is carried out for 2 crankshaft turns. At this time, the camshaft should make one turn. It is for this that the camshaft gear has two times more teeth.

The number of camshafts in the engine

This value, as a rule, depends on the engine configuration. Engines with row configuration and one pair of valves on the cylinder have one camshaft. If the 4th valve is provided on the cylinder, then two camshafts.

Opposite and V-shaped engines have one camshaft in collapse, or two, one camshaft in each head of the block. There are also exceptions associated with the design features of the engine model. (For example, the inline arrangement of four cylinders is one camshaft at 4 valves per cylinder, like Mitsubishi Lancer 4G18).

The modern market offers the consumer with different engines with different systems of changing the phases of gas distribution. The most characteristic of them:

VTEC - Technological development of Honda. The phase adjustment occurs by using 2 cams for an adjustable valve.

VVT-I - from Toyota. The phase adjustment is made by turning the camshaft relative to its drive stars.

Valvetronic - Technological development of the BMW company. The adjustment of the lifting height of the valves is due to changes in the position of the axis of rotation of the rocker.

Successes to you in the study of the engine device of your car.

carnovato.ru.

Camshaft - high-tech dictionary

The distribution shaft, in the abbreviated version, the camshaft is the main part of the main distribution mechanism or timing, an important element of the automotive engine. His task is to synchronize the intake and graduation cycles of the engine.

Constructive features

The location of this mechanism depends entirely on the design of the internal combustion engine, since in some models camshaft is placed at the bottom, at the base of the cylinder block, and in the other - at the top, right in the head of the cylinder block. At the moment, the upper arrangement of the camshaft is optimal, since this significantly simplifies service and repair access to it. The camshaft is directly connected to the crankshaft. They are connected between themselves with a chain or belt transmission by providing communication between the pulley on the shaft of the timing and an asterisk on the crankshaft. This is necessary because it is driven by crankshaft.

The distribution shaft is installed in the bearings, which in turn are securely fixed in the cylinder block. The axial backlash is not allowed due to the application in the design of the clamps. The axis of any camshaft has a cross-cutting channel inside through which the mechanism is lubricant. Behind this hole is closed with a plug.

Important elements are camshaft camshafts. In quantity, they correspond to the number of valves in the cylinders. It is these items that perform the main function of the GDM - regulation of the order of the cylinders.

On each valve there is a separate cam, which opens it through push to the pusher. Freeing the pusher, the cam allows you to straighten the spring that returns the valve into the closed state. The camshaft device assumes the presence of two cams for each cylinder - by number of valves.

The camshaft device.

It should be noted that the fuel pump and the oil pump dispenser is also carried out from the camshaft.

Principle of operation

The engine camshaft, located in the cylinder block, is driven by a toothed or chain transmission from the crankshaft.

Rounding, the camshaft turns the cams located on it on it, which alternately affect the inlet and exhaust valves of the cylinders, providing them to open-closing in a certain order, unique for each MODEL model.

The engine operating cycle (alternate movement of each of the cylinder valves) is carried out for 2 crankshaft turns. During this time, the camshaft must fulfill only one turn, so its gear has twice the teeth.

In one DVS there may be more than one camshaft. Their exact amount is determined by the engine configuration. The most common budget row engines with a pair of valves for each cylinder are equipped with only one camshaft. For systems with two vapor pairs, you need to use two camshafts. For example, power units with a different location of cylinders have or a single camshaft installed in the collapse, or a pair - for each block head separately.

Breakdown camshaft

There is quite a lot of reasons why the camshaft knock is woven into operation, which indicates the appearance of problems with it. Here are the most typical of them:

The camshaft requires proper care: replacement of seals, bearings and periodical defects.

1. wearing cams, which leads to the appearance of a knock immediately only when starting, and then all the time of the engine operation;
2. bearing wear;
3. mechanical breakage of one of the elements of the shaft;
4. problems with fuel supply control, due to which an asynchronism of the interaction of camshaft and cylinder valves arises;
5. deformation of the shaft leading to axial bias;
6. poor-quality engine oil, replete impurities;
7. lack of engine oil.

According to experts in the event of a lightweight camshaft, the car can ride not yet one month, but it leads to enhanced cylinder wear and other details. Therefore, when a problem is detected, it should be eliminated. The camshaft is a collapsible mechanism, so the repair is most often carried out by replacing it with all or only some elements, such as bearings.

Related terms

etlib.ru.

Distributional TRM

The camshaft (camshaft) is a key element of the gas distribution mechanism, which is responsible for the timely opening and closing of the intake or exhaust valve for supplying the fuel and air working mixture or the exhaust gas release.

The camshaft serves to synchronize the intake and release on the work of the engine's work. The part provides the functioning of the entire gas distribution mechanism, taking into account the procedure for the operation of cylinders and phases of gas distribution in relation to a particular engine.

The camshaft is a shaft with futs located on it. The camshaft rotates in the sliding bearings, which are made in the form of supports. Motor oil under pressure from the lubrication system comes to the joints of the camshaft over the channels. The number of camshaft camshaft corresponds to the number of intake and exhaust valves of the engine. One valve receives his cam, which exercises its discovery by pressing the pusher. At that moment, when the camshaft cam rumped from the pusher, then the valve closes under the powerful impact of the return spring.

From the shape of the camshaft camshaft depend on the phase of gas distribution. Under such phases are the points of opening and closing valves, as well as the duration of the stay of the valve in an open or closed state. Modern power units also have a system of changing the phases of gas distribution to increase the overall efficiency of the MRM and improve the characteristics of the FRO.

In the engines of modern cars, the camshaft is in the upper part of the cylinder head. The camshaft is connected to the toothed asterisk or the crankshaft pulley with a belt or chain transmission. The camshaft actuator protrudes the crankshaft.

On four-stroke engines, all the timing rotates twice as slower than the crankshaft, since the full working cycle of such internal combustion is carried out for two crankshaft turns. For these two turns of intake and exhaust valves, only one time should be opened. It turns out that the camshaft that controls the opening of the valves should be made only one turn for the working cycle.

In the design of the timing may be present not one camshaft. Often this is due to the number of valves per cylinder. Today, the diagram of four valves per cylinder and two-level timing valves is most widely used (one camshaft is the inlet valve drive, and the other interacts with the graduation). For V-figures, four camshafts are installed, since each series of cylinders has a separate GBC with two shafts. The timing system with one shaft is called SOHC (Eng. Single Overhead Camshaft), two-channel received the name DOHC (English Double Overhead Camshaft).

Read also

krutimotor.ru.

The camshaft (camshaft) is a piece of complex shape, equipped with cams, which at the right moment are opened from closed valve

Engine

The main feature of the camshaft is to synchronize the inlet and the release of the engine work clocks. In other words, this mechanism is intended for the timely opening of the valves and supply the fuel mixture into the combustion chamber. The moment of opening and closing the valves relative to the position of the crankshaft is called the camshaft phase.

Device and principle of camshaft

In the modern engine camshaft (most often there are two) is located at the top of the head of the cylinder block.

The camshaft is associated with the crankshaft engine of the car. The connection is carried out by chain (or belt) timing. For the reliability of efforts to the end part of the camshaft, a driven gear is attached, resembling a "star" on the rear wheel of the bicycle.

For adjusting the phases of the gas distribution and the procedure for the triggering of cylinders, camshaft camshafts correspond - their exactly as much as intake and exhaust valves are used in the GDM mechanism. The work is organized as follows: the camshaft camshaft "runs" to the valve pusher, presses on it and opens the valve. After the cam comers from the pusher, the valve closes under the action of a tight return spring.

The more valves in the gas distribution mechanism, the more camshafts installed in it. Bugatti Veyron has four camshafts and 64 valves

So, the camshaft rotates, thereby ensuring the effect of cams for the operation of intake and exhaust valve. The arrangement of cams relative to each other is carefully calculated in strict accordance with the phases of gas distribution and the order of triggering of cylinders. In other words, while the intake valve (or two valves) of one cylinder is opened, all other intake valves are at rest.

The amount of camshafts in the engine is determined by the configuration of the motor itself: if the engine has a row construction and one pair of valves per cylinder, then just one camshaft. If one cylinder accounts for 4 valves, it is advisable to use 2 camshafts - one of them serves only ink valves, the other is only the final. Among other things, the system with paired shafts has another plus - speed.

As for V-shaped and opposite motors, they can have either one distribution shaft at the site of the so-called "collapse" of the cylinders (the basis of the imaginary letter V), or two - one on each head of the cylinder block. You can try to implement a complex discovery and closing scheme of 16 valves with one camshaft, but not rational - the part will be too complex. Such schemes are rare, but Honda still decided to take one of them for weapons: a row motor with four cylinders and one camshaft is installed, for example, on the popular Honda Fit / Jazz model. The unconditional dignity of such a system is the ability to make the engine compact and easy.

Characteristics of camshaft

It is usually taken to allocate three important characteristics of the camshaft: this is the magnitude of the valve lifting, the duration of the opening of the valves and the camshaft phase.

For the sake of the maximum period of opening valves when constructing sports motors, engineers sacrifice idle. At racing cars, he is rarely below 2000 revolutions per minute

Valve lifting is measured in millimeters. This value is measured by the maximum distance to which the valve leaves from the so-called "saddle" in which it is at the time of closing. The duration of the opening of the valves is a segment of time during which the valves remain in the open state. Measure this value taken in degrees of rotation of the crankshaft. At the same time, each of the listed criteria is able to affect the operation of the engine: with an increase in the lifting of the valve, the duration of its opening or optimization of the phase distribution of the motor power is increasing. It is worth noting that it is the duration of the opening that is the main parameter with which the designers of forced motors work.

For example, the camshafts used in sports vehicles provide greater duration of the opening of the valves, compared with standard. This means that the valves remain open for as long as possible, allowing you to burn the maximum with this volume of the combustion chamber of the fuel dose for one tact. Unfortunately, in the technique to achieve one you have to sacrifice something to others: the installation of sports camshafts does not allow to keep the idle speed below 2000 rpm. Naturally, with such a work, the engine consumes a huge amount of fuel.

If we talk about the phases of the camshaft (the moments when the valves open and close relative to the camshaft position), then all information about them is usually contained in the data table, which is attached to the distribution shaft. The table indicates the angular positions of the camshaft, as well as information about when intake and exhaust valves are opened and closed.

Modern engines are often equipped with systems of changing phases of gas distribution. For example, some Toyota brand cars have a VVT-I system. Adjusting the phases of gas distribution occurs by turning the camshaft relative to its drive asterisk. Another example is the development of the Japanese Honda manufacturer, which received the designation VTEC - it allows you to change the phases using two cams for the adjustable valve.

blameper.ru.

What is the distributional shaft (camshaft)?

The distributional shaft in the engine is the finger-shaped axial mechanism driven by the crankshaft and having several elliptic protrusions on its surface (cams) - one for each intake and exhaust valve, which is in the engine. While the camshaft rotates (under the influence of the crankshaft), these elliptic protrusions regulate the opening and closing of the valves, pushing them in a certain sequence.

The first symptoms of the distribution shaft failure:

• Abnormal noise when operating valves
• Drying engine.

Maintenance of the camshaft is regularly inspection and, if necessary, replacing its seals. So, the replacement is usually carried out when the timing belt is replaced.

What is the distributional shaft (camshaft)? Video

howcarWorks.ru.

Engine distribution shaft

With all its external complexity and apparent unavailability for understanding, the engine is surprisingly rational and appropriately designed device. The purpose of any of its details is to ensure proper operation and maximum return from the engine. At the same time, literally all its elements are interrelated between themselves, but nevertheless, the work of the timing (gas distribution mechanism), as well as its foundation, the camshaft should be considered separately.

About cycles and engine work

DVS is a four-stroke power unit, it means that all processes associated with its work are carried out in four clocks. Their sequence is strictly defined, and when it is impaired, the work of such a motor is impossible. Sequence, i.e. The opening of the valves at the right time to output the exhaust gases and launch a combustible mixture, determines the camshaft that can be seen in the figure below.
Its main working element must be considered cams. It is they through the drive system that includes pushers, rocker, springs and other parts defined by the GDA design, carry out the opening of the valves at the right time. On each valve operates its cam when it is an existing protrusion, through the pusher presses the valve, it is lifted, and a fresh mixture may come to the cylinder, or its combustion products are displayed. When the protrusion leaves the pusher, then under the action of the spring the valve closes.

The cervical cerviff shaft is designed to install it on the specified locations, it rotates during the work. Drinking parts are hardened using high frequency currents and are lubricated in the process.

About the design of the camshaft

The device and timing drawing, including the camshaft, are shown below.
Structurally, the camshaft can be located either in the cylinder block or in the head of the power unit block. Depending on its location, the drive changes, thanks to which the force from the cams on the valve is transmitted. The camshaft drive is associated with crankshaft. The drive can be made as using a chain transmission (see the drawing above) and with a flexible belt. In addition, there may be other ways to transmit control efforts to valves, but it already determines the drawing and documentation of the motor.

What better to use the camshaft drive, determines the engine device. In cases where the camshaft is located in the cylinder block, (the so-called lower location), then the gear drive can even be involved. The latter, however, has not recently been applied due to their cumbersomeness and increased noise when working. That chain that belt drive is characterized by sufficient reliability, but each of them has its own features of operation that should be considered when maintaining the engine.
Its device may provide that the camshaft in the motor may not be one. As a rule, in modern multiclap engines, it is located if possible closer to valves to reduce load on it. The design and drawing, for example, a V-shaped engine, provides for at least two shafts, whereas in the usual inline, as a rule, one camshaft shaft. Although the multi-chamber engines will determine their purpose - may be separately exhaust and intake distribution shafts, i.e. They control the work of graduation or intake valves.

About working with crankshaft

Do not forget that for the camshaft, the main purpose is to ensure the correct gas distribution when the engine is running. For this purpose, the operation of the distribution and crankshaft must be consistent, i.e. The opening and closing of the valves is obliged to occur at the right moments - in the NTT position or NMT piston, or in accordance with the advance, which establishes the drawing or design documentation.

To fulfill such a connection on the GEAR gears, special labels make a coincidence of which means providing the right position of the distribution and crankshaft. To achieve this, a special method of adjusting their position is used.

Camshaft position sensor

With the transition to injector engines for these purposes, a special camshaft position sensor began to apply. So, on VAZ cars for this, the Hall sensor is served. Its work is based on changing the magnetic field, to create which the sensor device provides a magnet. When changing the magnetic field, which occurs when the camshaft is in the desired position, the sensor determines that the piston is located in the VMT position in the first cylinder, and transmits this data to the controller. In accordance with them, it provides fuel injection and its combustion, as it provides for the procedure for the operation of individual engine cylinders drawing or documentation.

Maintenance of camshaft

First of all, when carrying out regulatory work affecting the camshaft, it is necessary to pay attention to the state of the belts or the drive chain. The point is not even so much that the entire gas distribution mechanism will be disturbed, which provides camshaft, and in the fact that mechanical damage to both valves and piston is possible.

Sometimes the cause of the failure or improper engine operation is the position sensor. The manifestation of this may be the poor dynamics of the machine and considerable fuel consumption, as well as sunbathing the control light of the engine in the instrument panel. Defecting the fault and determining its source - the sensor is or not, is performed using a multimeter. Often the sensor itself is not possible, but wiring. In the event that defectation shows that the sensor is faulty, it must be changed.

The causes of the sensor failure can be:

• failure of the gear disk of the pulse sensor;
• his displacement due to impairment of fasteners;
• closing in the internal scheme of the sensor;
• the effect of increased temperature from engine overheating.

Properly performed defectation will avoid the failure of a new sensor installed instead of the old one.

The camshaft is the main node providing proper gas distribution when operating the engine, and often mainly ensures its effective operation. Its timely maintenance and control of the technical condition will allow you to operate the car correctly and without additional costs.

The main function of the camshaft (camshaft) is to ensure the opening / closing of intake and exhaust valves, with which the fuel assembly (fuel and air mixture) and the output of the formed gases is carried out. The camshaft is the main part of the GDM (gas distribution mechanism), which takes part in the complex gas exchange process in the automotive engine.

Modern TRM can be equipped with one or two camshafts. In the mechanism with one shaft, all intake and release valves are immediately served (1 inlet valve and release on the cylinder). In the mechanism equipped with two shafts, one camshaft starts the intake valves, another shaft - release valves (2 inlet valves and release on the cylinder).

The location of the gas distribution mechanism directly depends on the type of automotive engine. The timing with the top valve arrangement is distinguished (in the cylinder block) and with the bottom valve arrangement (in the head of the cylinder block).

The most common option is the upper location, so that it is possible to make effective setting and maintenance of the camshaft.

Principle of operation and camshaft

The installation of the phases of the distribution of gases occurs according to the installation labels, which are available on gears or pulleys. The correct installation ensures compliance with the sequence of the motion cycles of the engine.

The main part of the camshaft are cams. In this case, the number of cams, which is equipped with camshaft depends on the number of valves. The main purpose of the cams is the implementation of the phases of the phases of the gas formation process. Depending on the type of timing type, cams can interact with a rocker or pusher.

"Nockenwelle Ani". Under the license Public Domain from the Wikisklad site - https://commons.wikimedia.org/wiki/file:nockenwelle_ani.gif#mediaviewer/file:nockenwelle_ani.gif

The cams are installed between the supporting cakes, two for each engine cylinder. The camshaft during work has to overcome the resistance of the springs of the valves, which serve as a return mechanism, leading the valve to the original (closed) position.

The useful engine power is consumed to overcome these efforts, so designers constantly think how to reduce power loss.

In order to reduce friction between the pusher and the cam, the pusher can be equipped with a special roller.

In addition, a special desmodromic mechanism has been developed, which implemented an expedited system.

The supports of the camshaft are equipped with covers, while the front cover is common. It has stubborn flanges that are connected to cervous shafts.

The camshaft is made in one of two ways - forging made of steel or cast iron.

Systems of gas distribution phases

As already mentioned above, the number of camshafts corresponds to the type of engine.

In row engines with one pair of valves (one by one inlet and release valve), the cylinder is equipped with only one shaft. Two shafts are installed in row engines with two pairs of valves.

Currently, modern engines can be equipped with various phases of gas distribution phases:

• VVT-I. In such a phase technology, the rotation of the camshaft relative to the sprocket on the drive
• Valvetronic. The technology allows you to adjust the height of the lifting of the valves due to the displacement of the axis of rotation of the rocker
• VTEC. This technology involves regulating the phases of the distribution of gases through the use of cams on the adjustable valve

So, summarize ... camshaft, being the main link of the gas distribution mechanism, provides a timely and accurate opening of the engine valves. This is ensured by the exact fit of the shape of the cams, which are pressed on the pushers, force the valve to move.