Then I began to wonder, and how many valves is in the internal combustion engine. Because now the market is dominated by versions with 8 and 16 valves per cylinder. BUT really, no one ever did more or less the opposite? What other options were and why they did not go into mass production? Actually this will be today's speech, as usual it will be interesting + useful video. So read – I look.
How many valves in the engine?
THE CONTENT OF THE ARTICLE:
- Capacity and technical losses
- "8" and "16"
- 12 valve variant
- 20 valve variant
- 24 valve, and it happens
In this article we will talk specifically about the four-stroke engine, Pro two-stroke is a little bit different. It should be noted that the entire system timing (gas distribution mechanism), it is very important for the motor. Who and as soon as it is not "played" in order to increase its performance, but for some reason now the peak of the evolution of the considered motor with 16 valves. In this article, I will tell you about the types of power units which had different number of valves, and why they were discontinued and have not reached our days. THAT is to say the material is informative, but it will answer the question "how much" and "why"?
Capacity and technical losses
Actually the problem is timing, particularly valve one – as quickly as possible to bring the air / fuel mixture and also as quickly as possible to withdraw from the cylinder block. I think it's clear, and any difficulties does not cause.
And how to make sure to "blend" quickly go? YES like all just need to increase the diameter of the hole.
Thought so many engineers, the first valve motors were big enough, they closed down large passages in the cylinder head (which was on the intake and exhaust manifold). It should be noted that four-stroke engines has been with 8 valves, it is like classical scheme.
But the big valve has a greater inertia and at high revs increased mechanical losses. After all, the Cam of the camshaft, it was necessary to push that heavy gear.
Then they began to decrease. Yes, the loss decreased, but the bandwidth also decreased.
How to get out of the situation?
Began to increase the number, that is, to make them a tiny but more. So there are options with 12 – 16 – 20 and even with 24 valves. BUT again, only two have survived, the basic type is 8 and 16, i.e. 2 and 4 valves per cylinder (if you take the 4 cylinder engine).
"8" and "16"
As I wrote above – this is considered a classic layout. Only the second variant with "16" or 4 valves per cylinder, is more productive, capacity of approximately 15 – 20 HP more.
How this is achieved? In fact, very simple:
Have 8 valve Assembly, single camshaft, which in itself is merged and the inlet and outlet. Then there are those other Cams are on the same "rod", if one opens the intake, the second is in the opposite direction and it would not work. And then they change. Here a small chain, and in fact one gear (or sprocket), the phase shifters in such motors are rarely used.
8 valves
The 16-valve variant, it is much more complicated, but more efficient. Here there are two camshaft. Each shaft operates under its objective is to "intake" (intake valve opens) and there is a prom (prom respectively). Efforts are evenly distributed on two shafts instead of just one. There is an opinion that here the valve is slightly smaller than the "opponent with one shaft" — perhaps, however, you need to compare specific models of engine.