I was wondering how many valves there are in the internal combustion engine. After all, the market is now dominated mainly by versions with 8 and 16 valves per cylinder. But hasn't anyone ever done more or less? What other options were there and why they did not go into mass production? Actually, this is what today's speech will be about, as usual, it will be interesting.
In this material, we will talk about a four-stroke engine, about two-stroke engines, which is a slightly different topic. It should be noted that the entire system of hydraulic fracturing machine (gas-distributing mechanism) is very important for the motor. Who and as soon as it is not "played" to increase its performance, but for some reason now the peak of the evolution of the motor industry is considered a variant with 16 valves. In this material I will tell you about the types of power units that had a different number of valves, and why they were all removed from production and have not reached our days. There is a material, let's say, cognitive, but it will answer your question - "so, how much" and "why"?
Throughput and technical losses
The actual task of the hydraulic fracturing machine, and in particular of the valves, in particular, is to supply the air-fuel mixture as quickly as possible and to remove it from the cylinder block as quickly as possible. I think this is understandable, and it does not cause any difficulties.
And how to make the "mixture" faster? YES, it seems to be simple, you need to increase the diameter of the hole!
That's what many engineers thought, and the first valve motors were big enough to cover the large passages to the cylinder heads (which went to the inlet and outlet manifolds). It should be noted that the four-stroke motors were with 8 valves, it is as if a classic scheme.
Large and small motor valve
But the large valve has a large inertia and mechanical losses increased at high revolutions. After all, the camshaft cam had to be pushed through this heavy machine.
Then they were reduced. Yes, the losses have decreased, but the throughput has also decreased.
How to get out of this situation?
They started to increase the amount, i.e. make them miniature, but more. So there were variants with 12 - 16 - 20 and even with 24 valves. But again, only two survived, the main types are 8 and 16, i.e. 2 and 4 valves per cylinder (if you take 4 cylinder engine).
«8» и «16»
As I wrote above, it's a classic layout. Only the second variant with "16" or 4 valves per cylinder is more productive, with an output of about 15 - 20 hp more.
How is this achieved? In fact, it is very simple:
The 8-valve unit has one camshaft, which combines both inlet and outlet. That is, both cams are on the same "rod", if one opens the inlet, then the second is in the opposite direction and does not seem to work. Then they change. Here, a small chain and essentially a single pinion (or sprocket), the phase shifters on these motors are extremely rare.
8 valves
That's the 16-valve version, it's much more complicated but more efficient. There are two camshafts here. Each shaft works according to its own task - there is an "inlet" shaft (opening the inlet valves) and there is an outlet shaft (respectively). The forces apply evenly to two shafts, not one. There is an opinion that the valve itself is a bit smaller here than the "opponent with one shaft" - it is possible, but it is necessary to compare specific models of the engine.
16 valves
Often these units are fitted with hydraulic compensators that automatically adjust the thermal gap (eight-valve motors are rarely fitted with such a device). That is, I need to adjust the valves.
As a result, due to the increased number of inlet and outlet openings, the fuel-air mixture flows faster and is dissipated more quickly, without unnecessary mechanical losses. It should be noted that these options are often fitted with phase shifters, which further increases efficiency. As a result, a power of 15 - 20 hp is added.
To be continued in next part https://zen.yandex.ru/media/id/5d934fbd8d5b5f00b14d5a38/how-many-valves-are-in-the-engine-lets-look-at-the-rare-cases-part-2-5d948cc28d5b5f00b14d6385