Crank mechanism: assignment and arrangement, maintenance and repair
The engine is probably the most important unitin the car. It is he who produces the torque for the further movement of the machine. At the core of the ICE design is a crank mechanism. The purpose and the device of it will be considered in our today's article.
Design
So, what is this element in the engine?
This mechanism perceives the energy of the gas pressure and converts it into mechanical work. The CCW of an internal combustion engine combines several components, namely:
- piston;
- connecting rod;
- crankshaft with liners;
- rings and bushings.
Together they form a cylinder-pistongroup. Every detail of the crank mechanism makes its work. At the same time, the elements are interrelated. Every detail has its own device and purpose. The crank mechanism has to withstand increased shock and temperature loads. This determines the reliability of the power unit as a whole. Next, we will describe in detail each of the above components.
Piston
This part of the crank mechanismperceives the pressure of expanding gases after ignition of the combustible mixture in the chamber. The piston is made of aluminum alloys and carries out reciprocating movements in the block liner. The piston structure combines a head and a skirt. The first can have different shapes: concave, flat or convex.
On 16-valve VAZ engines pistons with notches are often used. They serve to prevent a collision of the piston head with the valves in the event of a break in the timing belt.
Rings
Also in the design there are rings:
- oil-removable;
- compression (two pieces).
The latter prevent the leakage of gases into the crankcaseengine. And the first serve to remove excess oil, which remains on the walls of the cylinder during the stroke of the piston. To ensure that the piston is connected to the connecting rod (we will describe it later), it also has bosses in its design.
Connecting Rod
The work of the crank mechanism is notdoes without this element. The connecting rod transmits the pushing forces from the piston to the crankshaft. These parts of machines and mechanisms have a swivel connection. The connecting rods are usually made by forging or stamping. But sports motors use titanium cast elements. They are more resistant to loads and do not deform in the case of a large shock.
- the upper head;
- rod;
- lower head.
At the top, this element is connected to the piston athelp your finger. The rotation of the part is carried out in the same lugs. This type of finger is called floating. The rod at the connecting rod has an I-section. The lower part is folding. This is necessary in order to make its dismantling from the crankshaft in case of malfunctions. The lower head is connected to the crankshaft neck. We'll look at the latter device right now.
Crankshaft
This element is the main component in thethe crank mechanism. Assign it to the following. The crankshaft senses loads from the connecting rod. Further, it converts them into a torque, which is then transferred to the box via the clutch mechanism. The flywheel is fixed to the shaft end. It is the final part in the engine design. It can be single- and double-mass. At the end has a toothed crown. It is needed to engage the starter gear in the event of engine starting. As for the shaft itself, it is made of high-strength grades of steel and cast iron. The element consists of conrod and radical necks, which are connected by "cheeks". The latter rotate in the liners (slide bearings) and can be detachable. Inside the cheeks and necks there are holes for oil supply. Lubricant penetrates at a pressure of 1 to 5 bar, depending on the loading of the internal combustion engine.
During engine operation,imbalance of the shaft. In order to prevent this, a torsional vibration damper is provided in the structure. It is two metal rings that are connected through an elastic medium (engine oil). There is a belt pulley on the outer ring of the absorber.
Types of GPGs
At the moment, there are severalvarieties of cylinder-piston group. The most popular is the in-line design. It is used on all 4-cylinder engines. There are also line "six" and even "eight". This design assumes the placement of the axis of the cylinders in one plane. Series engines are characterized by high balance and low vibration.
There is also a V-shaped design that went from the Americans. Scheme crank mechanism V-8 is presented below in the photo.
As you can see, here cylinders are located in twoplanes. Usually they are at an angle of 75 to 90 degrees relative to each other. Thanks to this design, you can save a lot of space in the engine compartment. An example can serve as 6-cylinder engines from the Opel C25XE. This V-shaped engine without problems is placed under the hood transversely. If you take a row of "six" from the front-wheel drive "Volvo", it will visibly hide the place under the hood.
But for compactness you have to pay lessvibration resistance. Another scheme for placing the cylinders is opposite. It is practiced on Japanese cars "Subaru". The axes of the cylinders are also placed in two planes. But unlike the V-shaped structure, here they are at an angle of 180 degrees. The main advantages are a low center of gravity and excellent balancing. But such engines are very expensive in production.
Repair and maintenance of the crank mechanism
Servicing any KSP assumes only a regular oil change in the engine. In the case of repair, attention is paid to the following elements:
- Piston rings. When bedding, they change to new ones.
- Crankshaft inserts. With a significant development or rotation of the slide bearing - a replacement for a new one.
- Piston fingers. They also have workings.
- The pistons themselves. At a detonation the head burnout is possible, which leads to a reduction in compression, trochanic, zhor oil and other malfunctions with the engine.
Often, such problems occur whenuntimely replacement of oil and filter, as well as using low-octane gasoline. Also, repair of the machine can be required at constant loads and at high mileage. Parts of machines and mechanisms usually have a high margin of safety. But there are cases when liners cranked for 120 thousand kilometers, valves and pistons burned out. All this is a consequence of untimely maintenance of the power unit.
So, we have found out what is the crank-connecting mechanism, from which elements it consists.
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