Camshaft - what is it? Description, purpose

2024 Author: Erin Ralphs | [email protected]. Last modified: 2024-02-19 11:41

The internal combustion engine consists of many components. An integral part of each internal combustion engine is a gas distribution mechanism. It includes a drive (chain or belt), intake and exhaust valves, gears, and a camshaft. This is a system that directly affects the stability of the engine and its performance. The timing system must be fine-tuned, and every component part must be in good working order. In today's article, we will look at what a camshaft is, where it is located and what functions it performs.

Characteristic, device

So, what is this detail? This is one of the most important parts of the timing mechanism, which is responsible for the timely opening and closing of valves. The camshaft itself is a rod on which there are several cams. The latter are teardrop-shaped details. They rotate on the axis of the shaft. The number of these cams is strictly determined by the number of exhaust and intakeengine valves. Also note that the operation of the camshaft is clearly synchronized with the pulley from which the rod is driven.

On both sides of the shaft put on special support journals. What is their task? The main function of the journals is to hold the shaft in the bearings. Also in the device of the mechanism there are oil channels. The physical wear of the cams, as well as the stability of the car engine as a whole, depend on their condition and throughput. To ensure lubrication, a through hole was made in the shaft axis from the leads to the cams and thrust bearings.

Features

This element is the main functional component of the gas distribution mechanism, since it is he who determines the order of opening the valves for the entry of the combustible mixture into the combustion chamber. Also, the order of opening the valves to remove gases that formed after the mixture ignited depends on the camshaft.

Now cars use engines with different numbers of camshafts. These are motors with one or two shafts. Since their number is different, the number of valves is also different. In the latter case, they are exactly twice as many. If we talk about most passenger car engines (four-cylinder), eight- and sixteen-valve engines are distinguished. They are equipped respectively with one or two camshafts. Many automakers adhere to the second scheme. Engines with an 8-valve head are practically not produced now (with the exception of some VAZ models). This is due to the fact that motors with a 16-valve head havehigher productivity due to better filling of the cylinders. Indeed, in the course of work, not two valves are already involved, but four.

Also note one more feature. The camshaft gear always has twice as many teeth as the crankshaft gear. This is due to the fact that in one working cycle the camshaft makes one revolution, and the crankshaft - two.

Location

Where is the camshaft? It depends on the design features of the engine itself. This element can be at the bottom or at the top. But still, most automakers practice installing engines with an overhead camshaft. This location greatly facilitates the maintenance and repair of internal combustion engines.

Working principle

As we said earlier, the element is driven from the crankshaft pulley, through a chain or belt. The shaft cam itself is in the shape of a drop. This form was chosen for a reason. When the rod is rotated, the extended part of the cam will press on the valve lifter. As a result, access to the combustion chamber for the mixture will open. After the working stroke, another cam operates. It causes the exhaust valve to open, so that the gases can successfully leave the chamber. This is exactly how the camshaft works. In simple words, at the right time, the cams open and close the engine valves.

Camshaft position sensor

What is this element for? This sensor is used to determine the angular position of the timing relative tocrankshaft. The element generates certain signals, which are then transmitted to the computer. Based on these signals, the control unit corrects the ignition timing, as well as the moment of fuel injection. Note that with the slightest malfunction of the DPKV, the gasoline engine will not be able to start.

And this element works on the Hall principle. When the magnetic gap is closed by a tooth (it is located on the drive disk or on the shaft), the magnetic field in the sensor changes. When a tooth passes next to it, a signal will be delighted that is transmitted to the computer. Depending on the rate of rotation of the camshaft, the pulse frequency will change. Based on the constant receipt of data on the position of the crankshaft, the electronics ensures timely, sequential fuel injection and the correct ignition of the combustible mixture.

In general, the sensor has a simple design and almost never breaks. However, if the element is out of order, it is not repaired, but replaced with a new one.

Camshaft repair

In general, this mechanism is very reliable and has a simple device. However, over time, the camshaft may need to be replaced. The fact is that working out is formed on the cams. Because of this, a characteristic knock occurs, and the valves do not close and do not open at the right time. The engine starts to run intermittently. If the problem is global, and the rod was deformed, or the cams were significantly damaged, the camshaft is replaced. And in case of wearbearing can be limited to repair. It is also important to control the cleanliness of the oil channels. The holes must not be contaminated, otherwise this will provoke oil starvation and premature wear of the cams. As a result, the camshaft will need to be repaired.

Conclusion

Now we know what a camshaft is and how it works. As you can see, this is a very important mechanism responsible for the timely opening and closing of the valves. In the event of a failure of this shaft, it is necessary to urgently take measures for repair. Otherwise, it will directly affect the state and operation of the internal combustion engine.