Automobile hydraulic compensator: operating principle and device

These parts have entered the design of the car relatively recently. In the 60's, they began to complete some models of cars. The device and the principle of the hydraulic compensator are interesting for many drivers, which means that you need to talk about them.

What does he do?

When the motor is wound up, all the parts in its construction are heated to sufficiently high temperatures. Even from the school course of physics, everyone knows that when heated, the bodies expand. In order to avoid breakages, rooted wear of individual parts, the entire engine there are special thermal clearances. When the engine warms up, they are absorbed due to the increase in the dimensions of those or other parts. But as the nodes wear out, their dimensions when heated, can not absorb the thermal gap. This is not the best way to affect the dynamic and other characteristics of powertrains.

Why is the hydraulic compensator in the car

The thermal clearance in the drive mechanism of the valve greatly affects the quality of work, and indeed the performance of the engine. Due to the natural wear of the parts, the distances on the valves are constantly changing. Even at the very beginning of the history of ICE, these gaps were regulated using an ordinary wrench. This process required regularity, which significantly increased the complexity and price for this procedure.

Therefore, engineers, to make life easier for car enthusiasts, developed a hydraulic compensator. The principle of its work is to absorb the gaps between the working parts of the camshaft, as well as between rockers, rockers, valves and rods. In this case, this compensation should not depend on the temperature or the degree of wear of parts and assemblies.

Types of hydraulic compensators

Install these nodes can be on any type of timing mechanism. Depending on what the design of the timing, there are four basic types of hydraulic compensators. These are pushers, hinges for levers or rocker arms, as well as roller pushers.

Despite the fact that the design of the mechanisms is different, the principle of their operation is the same. All of them are designed to compensate for the gaps between the valve tappets and the camshafts.

So, for example, the principle of the hydraulic compensators on the "Chevrolet Niva" is that instead of the traditional regulating the clearance of the screws now in the cylinder head plunger pairs were used. To these pairs a hydraulic working fluid comes from the lubricating system. This causes the lever to press against the camshaft cam all the time. With such devices, there is no need to adjust the gaps.

From the history of the creation of this mechanism

It is known that the very first car that was equipped with these small units is the Cadillac 452. It was collected in 1930. As the power unit used V16. On the convenience of maintenance and repair the car was not yet thought of, so the hydraulic compensator, the principle of its work was invented much later. So, there is information, then the popularity of these mechanisms came in the 80's, when the market was filled with Japanese cars.

How is the hydraulic compensator

Among the main details of this mechanism, you can distinguish the body, plunger pair, spring and check valve. As the body (and the body may be different depending on the design of the drive), cylindrical pushers, rocker arms or parts of the cylinder head may protrude.

The principle of the hydraulic damper is built on a plunger pair. It, in turn, consists of a bushing that allows the plunger to move in a certain direction. Also in the design can be identified plunger. This is a steel cylinder that has a hole in the bottom. A hole that connects the cavities inside the part and under it.

Some designs, where there is a one-arm lever, provide plungers without internal cavities. The plunger spring is located between the plunger and the bushing itself. A steel ball with a spring is used as a non-return valve.

Principle of operation of hydraulic valve compensator

So. At the moment when the camshaft cam is against its pusher with its underside, it does not compress anything. While the engine is cold, there is a gap between the cam and the pusher. The spring when the force is applied to it will begin to push the plunger until the distance disappears completely. At the same time, the oil from the car's lubrication system comes through a spring-loaded valve with a ball into the inner cavity of the compensator.

With the rotation of the camshaft, the cam presses against the body of the pusher. Thus, the body under pressure moves downward, closing the lubricating channels. The ball valve at this time is closed, and the pressure of the hydraulic fluid under the plunger is increasing. Since it is impossible to squeeze the liquid, the steam operates on the principle of rigid support, and the cam force is transferred to the valve stem. By the way, this principle of the work of the hydraulic compensators of the "Priora" showed itself perfectly.

Although the gap, which is only 0.8 μm in the plunger pair, the oil nevertheless leaves in a small amount through the technological cavity between the plunger and the bushing. So, the pusher slightly falls. Dimensions of subsidence may depend on the number of revolutions of the crankshaft. When the rpm is increased, the level of leakage of the hydraulic fluid from the plunger is reduced.

The clearance (at the moment when the camshaft cam comes off the pusher) is compensated by the force of the return spring, as well as the oil pressure. This principle of the auto-compensator auto helps to ensure complete absence of unnecessary distances between the elements. This can be achieved through tight connections between the nodes of the gas distribution system. When the engine heats up, the dimensions of the compensator parts also change, but these changes are compensated almost instantly.

Advantages and disadvantages

Using these mechanisms allowed the motorists to avoid the procedure for adjusting valve clearances manually. In addition, the engine became softer. Significantly decreased impact loads, which allowed to extend the life of the parts of the timing and reduce noise effects during operation of the unit. Hydrocompensator, the principle of its work also allowed to more accurately observe the time phases of the distribution of gases. This has the best effect on the safety of power units, power, dynamics and fuel consumption.

Among the shortcomings are the low-quality and noisy start-up of the cold motor. In the first few seconds, the oil pressure has not reached the required level, so the expansion joints can knock a little. This is actual even on foreign cars, because the principle of operation of the Hydrocompensators "Great Wave" differs little from domestic developments.

Causes of failure of parts

Despite the simplicity of the design, these nodes also fail. In most cases, the most popular reason is the dirty motor lubrication channels. Or strong wear of the working part of the valve back. Contamination can result from the use of an incorrect oil, a replacement not carried out at the right time, or a breakdown of the oil filter.

If the seed clearance of the plunger pair is increased, the technological leakage of oil may increase. The rigidity with which the hydraulic compensator works is lost, the principle of its operation is such that the oil pressure must be present. The same happens if the check valve of the high pressure chamber is strongly worn.

Inside, the hydraulic compensator must be filled with a lubricating hydraulic fluid. If there is air in the cavity, the gaps will not be compensated completely, or even not at all. In this case, the repair of hydraulic compensators can help. Also, repairs may be required if the part has jammed, foreign particles have got into the mechanism.

How can this be avoided?

Keep the inside of the engine clean. It is recommended to replace lubricants and filters regularly at the manufacturer's recommended time. Also, flush the motor regularly before replacing the grease. It is necessary to know that small gaps in a hydraulic compensator require the use of very high-quality oils. You can use synthetic or semi-synthetic oils of medium viscosity.

Diagnostics and repair of hydraulic compensators

Diagnose the broken element by a characteristic knock. Then the suspicious mechanism must be removed and visually inspected for wear and damage. If the part is dirty, it is recommended to rinse it in acetone.

For the elements to work properly, there is a special additive for hydraulic compensators. The tool allows you to eliminate the causes of machine noise during operation, and also effectively cleans this part.