How does the prechamber diesel engine work

Engine with pre-chamber flare ignition. How it works.

Hello to all subscribers!) This chapter is not part of my review of the “Wheels of the Country of the Soviets”. But it is made by your requests – I will tell you briefly about the work of the prechamber engine. It will be done by example of engine GAZ 3102 “VOLGA” ZMZ 4022. So.

The very first engine ZMZ 4022.10 (1981-1992).

The impetus for creating an engine with fork chamber flame ignition at GAZ was the mass production of such engines in 1972 by the Japanese company Honda, which was able to bypass the priority of domestic patent. The Soviet engine was designated GAZ-4022.10. It differs from its predecessor GAZ-24D in having a new cylinder head with other gas channels, additional small intake valves for prechamber, an air intake system, a tuned exhaust, increased valve travel, and an upgraded camshaft.

In addition, the K-156 carburetor of original design, the ignition distributor, new engine cooling system (like the VAZ-2101 engine) were developed, and a water pump was introduced in the cylinder block. For the first time on these GAZ engines an air filter with a paper filter element was used. Then documentation for production of GAZ-4022.10 engines was handed over to Zavolzhsky Engine Plant, which began serial production since 1981, but under a new name – ZMZ-4022.10. The biggest number of these engines was produced in 1986 – 4000 pcs. Totally during 11 years were made about 27 thousand of GAZ-3102 with ZMZ-4022.10 engines.

The acceptance tests of GAZ-3102, which was equipped with GAZ-4022.10 engine, were carried out in 1980. They showed the advantage of this car over GAZ-24 in fuel efficiency and toxicity of exhaust gases, especially in terms of carbon monoxide emission. In the same year the first 25 cars with this engine were produced. The principle of pre-chamber flame ignition was developed by the Gorky automobile plant (author – G.V. Evart) in cooperation with specialists from the Institute of Chemical Physics of the USSR Academy of Sciences back in the 1950s. The certificate of authorship for the development was received on December 18, 1956.

Scheme of the engine with pre-chamber flare ignition:

1 – cylinder; 2 – piston; 3 – prechamber feed channel; 4 – prechamber section of the carburetor; 5 – carburetor; 6 – intake channel; 7 – main chamber intake valve; 8 – rocker bead; 9 – rocker arm; 10 – adjusting screw of the additional rocker arm; 11 – cylinder head; 12 – prechamber valve; 13 – spark plug; 14 – prechamber; 15 – nozzle; 16 – main combustion chamber; 17 – rod; 18 – pusher; 19 – camshaft alloy; In the cylinder head are the main combustion chambers 16 and close to them prechamber 14. Each prechamber is connected to the main combustion chamber with two holes (nozzles) with a diameter of 3.5 mm. The volume of the prechamber is small (3.8 cm3), and in it is screwed spark plug 13. During the rotation of the camshaft 19, the cam runs over the pusher 18 and moves it upward with the rod 17. It rotates the common rocker 9, which has a bead 8, located above the end of the inlet valve stem 7 and an additional arm with an adjusting screw 10. Turning the rocker opens the additional prechamber valve 12 and then (almost simultaneously) the inlet valve 7 of the main combustion chamber. Combustible mixture enters the prechamber from the prechamber section 4 of the carburetor 5 on a separate channel 3 feeding, made in the intake pipe and the cylinder head. When an additional valve 12 in the prechamber receives enriched (IX = 0,85 -;- 0,90), and the main chamber and the engine cylinder (with an open intake valve during the movement of the piston 2 down very poor (IX = 1,8), combustible mixture. At the end of the compression stroke between the electrodes of the spark plug 13 electric spark slips, and the working mixture in the prechamber is ignited. From the prechamber combustion products of the mixture are ejected through two nozzles into the main combustion chamber in the form of two burning flares. These swirl and ignite the lean mixture. This achieves fast, reliable and complete combustion of the combustion mixture in the main combustion chamber. The flame chamber method of ignition of the operating mixture provides high combustion rates and efficient combustion of poor mixtures during engine operation under normal operating conditions. This significantly improves the engine economy. The use of poor combustible mixtures eliminates fuel underburning, which significantly reduces exhaust gas toxicity. Only for maximum engine power, when the carburetor throttles are almost fully open, the mixture composition is enriched. The use of pre-chamber flare ignition of the working mixture in the engine has also entailed some changes in the carburetor. The engine is equipped with a K-156 carburetor with dropping mixture flow, which has two main chambers and one additional chamber for the pre-chamber system. Opening the throttle main chambers are sequentially, as in the carburetor K-126r, installed on the engine GAZ-24 “Volga”. Throttle opening of the prechamber section of the carburetor occurs due to kinematic connection with the throttle of the primary chamber of the carburetor. In fact, in all modes, the engine runs on poor mixtures, only the enriched mixture is used for ignition. To put it simply, an enriched mixture is injected into the prechamber next to the primary chamber. a lean mixture is fed into the primary combustion chamber. In the prechamber, the rich mixture is ignited from the spark plug and is fed under pressure into the main chamber, where it mixes with the lean mixture and burns all together.

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Model – ZMZ-4022.10 Type – carburetor, four-cylinder, with forkamerno – flare ignition Cylinder diameter and stroke – 92 * 92 stroke of the cylinder capacity, l – 2.445 Compression Ratio – 8.0 Maximum power, hp. – Maximal torque at 2500-3000 rpm, kgf*m – 18,5 Grade of gasoline – AI-93 Weight of unloaded engine with clutch and gearbox, kg – 210 Only on GAZ-3102 naturally from all Volgas was installed pre-chamber motor, but sometimes there were engines installed on GAZ-31029 and GAZ-24. The meaning of pre-chamber is that first the mixture is ignited with a spark plug in a separate combustion chamber (pre-chamber), and then hot gases from it ignite the mixture in the main combustion chamber (mixture is poorer, and from an ordinary spark can not be ignited).

Differences from the 402 engine: The block has liners with top seating and bottom sealing with 2 rubber rings. Its own aluminum pan cover and clutch bell (interchangeable with 402). The cylinder head is a completely different cylinder head with its manifolds, rocker arms, valve drive rods, valve covers. The main valves are interchangeable with the 402. Additional valves are original (no analogs exist). The cylinder-head gasket is original (interchangeable with 402). Carburetor – original, three-chamber K-156 (no analogues).

Trambler – contact with “Moskvitch” characteristics without a vacuum generator. Tumbler actuator with fixing type “clamp”. It is possible to temporarily put the tumbler, the tumbler actuator, the switch and the coil from the 402, but the ignition timing characteristics are different and it will “ring”…

Distinctive “chip” – the system of staged air start. Serves to supply air into the intake manifold bypassing the carburetor during engine braking, more precisely, when the rarefaction in the intake manifold exceeds 540mm Hg Consists of an electronic vacuum switch block (VSTB) – the sensor and two solenoid valves. When reaching the specified limit of rarefaction in the intake manifold and engine speed 1700 rpm or more, the electronic unit turns on the first solenoid valve, and when reaching speed 2500 or more, the second solenoid valve turns on.

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Thermostat is in a special housing, connected to the water pump, radiator and water distribution nozzle cylinder (interchangeable with the thermostat 402go when installing water distribution nozzle combined with thermostat housing (ie when installing the entire system of thermal management of 402)). For example, video of this engine

Especially for this engine was developed a three-chamber carburetor K156. I must say it’s a finicky carb, requiring constant adjustments and they are quite complicated and accurate. Here’s his description. The K-156 carburetor (Figure 1.47). It is designed for the pre-camera engine ZMZ-4022L0 of the car “Volga” GAZ-3102.

It is a three-chamber carburetor with two main primary and secondary sections and one auxiliary pre-chamber section, with a falling combustible mixture flow and balanced float chamber. Float mechanism is made with the bottom fuel supply, idling system in the primary and prechamber sections, the system starts and warms up a semi-automatic type,

Cold engine starting system consists of pneumatic actuator, lever system, forming semi-automatic starting device, and air damper 8, closing of which before starting the cold engine is carried out by the driver by means of a manual actuator. The float mechanism is equipped with a fuel inlet and outlet connection 1 to the gasoline tank, the fuel valve 2 with a filter 36 and the float L

Each section has its own main metering system containing emulsion tube 30 with air nozzle 7$ main fuel nozzle 32, atomizer made in a small diffuser, and throttle valve with actuator lever.

The main metering system of the secondary chamber contains an emulsion tube 27 with air nozzle 11, the main fuel nozzle 26, atomizer, made in the small diffuser with a locking throttle with a drive lever.

The main metering system of the prechamber section includes an emulsion tube 23 with an air nozzle 17, the main fuel nozzle 21, located in the float chamber of the prechamber section, the atomizer, made in the small diffuser 16, and the throttle valve 25 with the lever

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This type of engine has gained a disgusting reputation with drivers. Because of the great unification with the usual 402 (what is the difference written above), the heads were changed to the usual. Well all, thank you for your attention!)

The principle of action of the pre-cam diesel engine

As you know, today many manufacturers are looking for options on how to increase the economy of internal combustion engines. They have found one possible way out of this predicament. The method is to have the engine run on fuel mixtures that contain a smaller percentage of fuel. Not only would this approach increase fuel efficiency, but it would also reduce waste emissions. But there is a flaw in this method: when the mixture contains a small amount of fuel, it ignites worse. Therefore, the developers came to the conclusion that for the stable operation of the engine, an initial focus of combustion is needed, from which the fire will spread quickly throughout the entire space of the fuel-air charge.

Engine with pre-chamber ignition

As a result, there are now two options for obtaining such a hearth: a spark of increased energy and layer-by-layer distribution of the mixture (by the time the spark is produced, a flammable mixture is formed). The second way includes several variants. Today, however, we will take a closer look at the variant called pre-chamber-flare ignition.

The cavity located in the head of the internal combustion engine cylinders is called the prechamber, or prechamber. It, using one or more channels, connects to the main combustion chamber. This type of engine acts as a diesel as well as a gasoline engine. Generally, the intermediate chamber can also have another name: vortex chamber. Based on the name, it becomes clear to us that the fuel in such a chamber is swirling. This effect contributes to a better mixing of fuel with air. But, describing the work of ICE with prechamber, it is important to note that initially the fuel, getting into the preliminary cavity, collides with its walls and mixes with the air, in this kind of motor is inferior to its likeness.

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When ignited, the fuel is quickly directed into the key chamber, using the connection channels we are already familiar with. The excellent factor that such channels have, in comparison with their counterparts, is that the sections in them are coordinated so that a significant pressure difference is created between the prechamber and the key cylinder. Fuel spills over the entire area of the prechamber and burns there almost completely. The final phase is the combustion of the fuel in the main chamber, or rather its remains.

Due to the fact that in the main compartment the fuel has already burned down and does not need to continue its way, the parameters of the piston recesses are small.

What is the purpose of the pre-chamber in the engine

Now let’s deal with the most important question: what is the purpose of the prechamber in the engine?

Primarily such system was created with the purpose to relieve, even partially, the load on the pistons. This, in turn, had a positive effect on the overall performance of the engine. Moreover, by choosing the pre-chamber engine, you reduce the amount of toxic waste, because, specifically in our case, the diesel is completely burned. We conclude from this that your fuel costs will be reduced.

The pre-chamber flare ignition system

The main elements that make up a diesel engine with a pre-chamber are:

Note: we will go through the path with the fuel in order to fully understand how a pre-chamber engine works.

The prechamber valve

  1. A conduit leads the fuel to the pre-chamber.
  2. Then passes a section designed for the over-enriched mixture.
  3. The valve of the prechamber itself. performs its main role (igniting the fuel when the injectors inject it).
  4. At the same time as the spark ignites the fuel, the distributor timing injects fuel into the main chamber, through what opens the valve.
  5. Now the fuel is at the finish line – in the central chamber of the combustion engine.
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Flame prechamber ignition system

By now, we hope, it has become clear to you how the pre-chamber diesel works and what the pre-chamber device consists of.

Pros and cons of pre-chamber engines

Mentioning the internal combustion engines working on gasoline, we can confidently declare their inefficiency, as the device was imperfect and in motion showed itself from the worst sides. Therefore, none of the manufacturers wanted to rely on such a choice, and as a result, such designs are not used now. Of course, initially people favored such counterparts because of the economy in fuel consumption and, at the same time, the reduction in the toxicity of the waste emitted. But users have changed their minds after testing the units for durability on the road.

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The situation is quite different when it comes to diesel engines, which are our main object of study. The pluses in an engine with a pre-chamber engine are the insignificant smokiness of the power unit, regardless of the way of driving and, what is also weighty, such units do not need selective fuel.

Diesel engine

Let’s go back to the negatives, how could it be without them? The engine does not start well when not warmed up. Why is it so? The point is that for a stable start it is necessary to warm up the pre-chamber well, but, due to the fact that in this system electric glow plugs are installed, the air is not heated to the full extent.

In conclusion, it can be noted that the principle of operation of such engines has few disadvantages, so you can safely give it a preference. Enjoy your rides and don’t forget to leave your comments below.

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