After replacing the timing belt or high pressure fuel pump (high pressure fuel pump) on a diesel engine, there is often a problem with finding the marks to which the injection pump pulley must be set. Its incorrect position leads to untimely fuel supply and improper engine operation. To avoid this, you should act in a proven way.
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Instruction
First of all, unscrew the high pressure pipe from the nozzle of the first cylinder of the engine. Put a transparent plastic tube on it so that it is directed upwards and you can clearly see the level of fuel filling it. The tube should fit well on the nozzle. To secure it, use a screw clamp. Fuel must not leak!
Remove the timing belt...
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The principle is common to all diesel engines, be it BMW, AUDI, FV, tractor or anything else.
Here I will give two original texts and my explanations. Unfortunately, I wrote on the forum, so the comments are not in the 3rd person.
Text #Time
The sequence for checking the angle (moment) of the start of fuel supply: clean the body of the oil filler neck and the hour meter from dirt and dust, as well as the place where the high pressure pipe of the first cylinder is attached to the fuel pump;
set the piston of the first cylinder to the position corresponding to the end of the compression stroke (to do this, turn on the decompression mechanism and, rotating the crankshaft, align the marks on the timing gear cover and the fan drive drive pulley: when using the UTN pump with the fifth mark from TDC of the “T” mark, when using pump ND-21/4 from the second, when using the pump ND-21/2 from the first);
remove the oil filler housing together with the motor meter and disconnect the splined flange from the fuel gear...
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You won't put it on yourself! you don't even have to try!
I can tell you from my own experience!
better look for smart masters!
and to confirm my words ... here's a tip for you:
The dynamic angle is measured with a special professional stroboscope while the engine is running at idle (740 rpm). It is regulated, of course, on a stopped one and is checked again on a running one. If necessary, the adjustment is repeated until the desired result is obtained. Few people have professional strobe lights, so it's not surprising that your masters don't have one. We don't have it, and it's too expensive. Therefore, there is a method for setting the advance in statics, i.e. on a stationary motor. In static advance on your motor should be 24 degrees before TDC. There are two technologies for setting the static lead.
1 - drip method. The pressure valve of the 1st cylinder is removed from the injection pump. The discharge valve fitting returns to its place and a piece of high-pressure tube is put on it ...
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No one needs to explain that the advance of fuel injection for diesel engines is very important. Naturally, for each engine speed, a certain value of the advance angle will be optimal, for example, for idling 800 rpm is 3 °, 1000 rpm - 4 °, 1500 rpm - 5 °, etc. . To achieve such a dependence, which, by the way, is not linear, there is a special mechanism in the injection pump housing. However, this is just a piston (sometimes in the literature it is called a timer), which moves inside the high-pressure fuel pump by fuel pressure and, through a special leash, unfolds a special washer with a wave profile at one angle or another. The piston will be pushed further - the washer wave will run into the plunger a little earlier, it will start moving and start supplying fuel to the nozzle earlier. In other words, the injection advance angle depends on the fuel pressure inside the injection pump housing and on the degree of wear of the washer wave profile. As a rule, there are no problems with fuel pressure. Well, isn't...
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Everything is correct for the Bosch mechanical high-pressure fuel pump or its Ziksel Kiki clone, except that the high-pressure pipes must be weakened to the limit, but it is better to remove them. Otherwise, you have to forcefully rotate the pump in one direction or another, and because of this, the tubes are then in one-sided tension, and taking into account the fact that the tubes experience vibration on their own with impulses of fuel movement under a pressure of 127 kg / cm, then this is fraught with further occurrence of microcracks on them, which are not always successful in welding, I tried, I know. The size of the Bosch injection pump plunger lift is usually the same for everyone and depends on the engine size, for example, for 1.6 liters. turbo it is 0.75...
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How to set injection timing
on diesel.
It happens that after replacing the timing belt (timing) or fuel pump (high pressure fuel pump) on a diesel engine, it is difficult to find the marks by which the high pressure fuel pump pulley must be set to ensure timely fuel supply. How to be?
You can, of course, try to "catch" the required position of the fuel pump pulley using the "scientific poke" method, i.e. put in one position and try to start the engine.
It didn’t start - turn the injection pump pulley 3-5 teeth relative to the toothed belt in any direction and try again.
It started up, but knocks hard - early injection, which means it is necessary to turn the pulley 1-2 teeth against the direction of rotation and start the engine again.
It started up, but smokes and works very softly - late injection, you need to turn the pump pulley 1 tooth in the direction of its rotation.
After it is no longer possible to achieve fine adjustment by rearranging the belt, it is necessary to loosen the nuts for fastening the high-pressure fuel pump and turning ...
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Checking and adjusting the advance angle of the supply or injection of fuel on the engine
The connection marks on the drive parts are supplied for the new pump and motor. During operation, the plunger pairs and gears wear out and the injection advance angle changes. Therefore, after connecting according to the marks at the pump, it is necessary to check the actual angle, injection advance and, if necessary, correct it using an adjusting device in the drive mechanism. Nominal injection advance angles are shown in Table 9. It is difficult to measure advance angles directly. Therefore, for each motor, auxiliary values are given (for example, the length of the arc of the fan drive pulley), available for measurement.
By analogy with the adjustment of the pump on the stand, the fuel injection advance angle on a diesel engine is determined by the moment the supply starts and the moment the fuel injection starts.
For most diesel engines, when checking the angle of the feathers; e-tion at the moment the feed starts ...
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Checking and adjusting the fuel injection advance angle YaMZ-238
To adjust the fuel injection advance angle, two hatches are provided on the flywheel housing (see Fig. 1), and the angle values \u200b\u200bare marked on the flywheel in two places. For the lower pointer 3, these values are made on the flywheel in numerical terms, and for the side pointer 4 - in letter terms, while the letter "A" corresponds to the value in numerical terms of 20 °; the letter "B" -15 °; the letter "B" -10 °; the letter "G" - 5 °.
Rotate the engine crankshaft clockwise (when viewed from the fan side) until the marks on the crankshaft pulley and the distribution gear cover or on the flywheel with the pointer are aligned, corresponding to the fuel injection advance setting angle -...
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Setting the fuel injection advance angle. All you need to know Not a small number of modern cars can drive diesel and therefore many motorists want to know about such a procedure as setting the fuel injection advance angle. Definition and its correct installation is of fundamental importance for the quality work of a diesel engine. Here it is worth noting the fact that a certain speed has its own, universal.
There are already well-established indicators, for example, for 800 rpm, and this is idling, the lead angle will be 3 degrees, for 1000 rpm it increases to 4 degrees, at 1500 it becomes already 5 degrees.
Contrary to popular belief, this dependence is not linear, which can be seen in the example shown above. To set the most optimal angle for a given torque, a mechanism is installed in the TNDV, although to be precise, this is the simplest piston, which is sometimes called a timer. His...
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1 Engine ignition system - the difference between a "diesel" and a gasoline engine
Due to these differences in the process of ignition of gasoline and diesel fuel in the engine, one can also note the difference in the structure of ignition. It is obvious at least that there is no such system as in a gasoline car, consisting of a breaker-distributor, a switch or pulse sensors, in a diesel car. However, in winter, it is sometimes difficult to start a diesel engine, due to the fact that the air is too cold, so a special preheating system is installed to increase the temperature of the air in the combustion chamber.
We can say that setting the ignition on a diesel engine is nothing more than choosing the fuel injection advance angle. And this is achieved by adjusting the position of the piston, at the time of injection of the "diesel" into the cylinder. This is very important, because if the angle is chosen incorrectly, the injection will be untimely, and, as a result, the fuel will not burn to the end ....
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Glow plugs
Any pre-chamber diesel engine is equipped with glow plugs for stable starting. Their main task is to warm up the air and prechamber before starting the engine. After the diesel engine has started, the spark plugs are not involved in the operation of the diesel engine. In some European and Japanese diesel engines, candles still work constantly or intermittently until the engine warms up and when it is hot, but this is not necessary for stable operation, but to reduce harmful emissions. If your pre-chamber diesel does not start, then in 90 cases out of 100, candles or glow relays are to blame. The easiest way to check the candles is to disconnect the wires from the relay from the spark plug terminal and touch this terminal with a wire from the battery positive. The main rule is that you need to touch it for a short time, since the battery voltage is 12 - 13 volts, and the voltage supplied to the candles sometimes does not exceed six volts. In the presence of...
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04.12.2007
No one needs to explain that the advance of fuel injection for diesel engines is very important. Naturally, for each engine speed, a certain value of the advance angle will be optimal, for example, for idling 800 rpm is 3 °, 1000 rpm - 4 °, 1500 rpm - 5 °, etc. . To achieve such a dependence, which, by the way, is not linear, there is a special mechanism in the injection pump housing. However, this is just a piston (sometimes in the literature it is called a timer), which moves inside the high-pressure fuel pump by fuel pressure and, through a special leash, unfolds a special washer with a wave profile at one angle or another. The piston will be pushed further - the washer wave will run into the plunger a little earlier, it will start moving and start supplying fuel to the nozzle earlier. In other words, the injection advance angle depends on the fuel pressure inside the injection pump housing and on the degree of wear of the washer wave profile. As a rule, there are no problems with fuel pressure. Well, unless the fuel filter is clogged, the pressure reducing valve plunger is stuck in the open state, or the vanes of the supply pump (inside the high pressure pump) are stuck. (Fig. 38, Fig. 39)
rice. 38 fig.39
Rice. 38. To fully check the pressure reducing valve, it can be unscrewed from the injection pump. The plunger inside this pressure reducing valve must not be jammed. Whether this is true or not, you can check by pressing a match on the plunger. Under the influence of the hand, the plunger should move easily, compressing the spring.
Rice. 39 . Unscrewing the pressure reducing valve on an already removed pump is not difficult. Doing the same without removing the injection pump is already more difficult.
The condition of the pressure reducing valve (may be stuck) and the feed pump can be assessed using the manual fuel pump. If the operation of the engine changes after you start pumping with a hand pump with the engine running, i.e. start to manually raise the pressure in the injection pump housing, then either the valve or the pump is faulty. The pressure reducing valve can be easily unscrewed without removing the injection pump and checked. Only on most diesel engines of the company "
Mitsubishi »To do this, you have to remove the corner of the bracket with a thin chisel, after which the head of the pressure reducing valve becomes accessible to a special key. By the way, this pressure reducing valve can also be turned out with a long barb (prong) without using a key. (FIG.40)
Rice. 40. It is possible to raise the pressure in the high-pressure fuel pump housing by upsetting the plug (1) of the pressure reducing valve (2) with a thin beard. As a result of these impacts, the spring (3) will press the plunger (4) harder and it will block the fuel discharge hole (5). To return the plug back (reduce the pressure in the injection pump housing), it is necessary to punch the plug down harder so that it compresses the spring completely and presses the plunger in such a way as to push out the stopper (6). After that, both the plunger and the spring fall out easily. Next, you need to turn the pressure reducing valve over and punch the plug back with a thin beard. Then put everything back in place and try again to adjust the pressure.
There, all seals are made on rubber rings (torics) and strong tightening is not required. If this valve is intact, its plunger is not stuck in the open position, then a malfunction of the supply pump should be suspected. Provided that when pumping fuel, the engine becomes smoother. True, if fuel with air bubbles flows from the overflow (return) line during engine operation, then first of all it is necessary to eliminate air leakage. Because if there is an air leak, it is difficult to create the required pressure in the injection pump, even with a well-functioning supply pump. But problems with air leakage are a separate issue. Here we only note that air leakage, even with external power supply, i.e. when the fuel canister is above the injection pump, it is possible through the oil seal of the injection pump and through the lack of density of the central plug on the cast-iron part of the injection pump. This plug is used to accurately set the injection pump according to the fuel supply angle (it is unscrewed, a micrometer head is installed and the plunger stroke is measured, this procedure is described in almost all injection pump repair manuals). With a fully serviceable injection pump, even if it was previously air-filled, after 10 minutes of engine operation there are no air bubbles in the overflow line.
So, the injection advance angle depends on the engine speed. To save fuel, achieve high power and in terms of ecology, it would be better if this advance angle changes taking into account other engine operating conditions, such as engine load, boost pressure, temperature, etc. But it is possible to fully take into account all these conditions only for high pressure fuel pumps with electronic control. For conventional mechanical ones, only the fuel pressure in the injection pump housing and, on more modern units, the temperature of the engine coolant are taken into account. The piston in the lower part of the high-pressure fuel pump moves depending on the fuel pressure and, through a special steel “finger”, slightly unfolds the profile washer (the same washer is forcibly rotated by the leash from the heating device mechanism). As a result, the wave protrusion of the washer will run into the plunger earlier, and it will start its movement earlier. This whole system was calculated and made at the factory and, at the very least, coped with its duties. Until heavy wear and tear begins. It became intense because fuel without lubrication began to flow into the high-pressure fuel pump (our “dry” winter fuel, like kerosene, almost does not contain heavy fractions, which provide lubrication of all rubbing parts), fuel with air and just dirty fuel ( with abrasive). However, ordinary old age also does its job. As a result, the protrusion on the washer begins to run into the plunger a little later, and the plunger, in turn, starts its movement a little later. In other words, later injection starts. The beginning of this phenomenon looks like this. The engine is idling and, due to varying wear of the injectors, shakes a little. We add turns to it. At about 1000 rpm, the engine stops shaking and seems to freeze - it runs smoothly - smoothly. We're still ramping up. And suddenly, in the range of 1500 - 2000 rpm, shudders appear. These shudders (shaking) can appear both with a smooth, but intense, and with a slow increase in speed. When shaking, blue smoke comes out of the exhaust pipe. When the engine is fully warmed up, shaking around 1500 - 2000 rpm disappears. This is at the very beginning of the development of the defect. Then the shaking does not disappear even after the engine warms up. Exactly the same shaking appears if you increase the injection pressure on the injectors. In this case, if the injection pump is worn out, you will also get late fuel injection. We get rid of this phenomenon by turning the injection pump housing to an earlier injection. Sometimes you have to turn the injection pump almost to the stop. But before you do that, listen to the operation of the engine. When a diesel engine has too early injection, it starts to work harder (they also say that it has valve knocking). And if you make sure that this hard component in the acoustic background of the diesel engine has disappeared 50-100 revolutions before the start of shaking, then you definitely need to turn the high-pressure fuel pump. It should be noted here that for worn-out diesel engines, the piston-cylinder gap is very large and therefore they begin to work hard even with an absolutely correct injection advance angle. The use of a stroboscope to set the injection advance in our case is not entirely justified. Let's not talk about the fact that stroboscopes more confidently catch the knock of an already heavily worn nozzle with their microphone. If the nozzle is in good condition, and the fuel supply pipe is fixed properly, the strobe lamp, as a rule, malfunctions. You can set the injection advance at idle using a stroboscope. It is this advance that is given in the technical documentation. But the wear in the injection pump is uneven. And very often by setting the lead on the mark with a strobe at idle speed, we do not get rid of the shaking at speed caused by late fuel delivery. Therefore, we recommend setting the lead by ear. With the wear and tear that our diesel engines have, this is a more acceptable way. After all, this is the only way to compensate for late injection caused by low fuel pressure in the injection pump housing due to wear of the supply pump. This is almost the same as adjusting the ignition timing for petrols. You can use the instruments to set the ignition advance only at idle speed (and the other is not offered by the repair manuals), but due to a malfunction, for example, of the centrifugal regulator, the car will not drive. It is clear that it needs to be repaired or replaced. But you can, by turning the distributor, set by ear an acceptable ignition timing. The only difference is that for gasoline engines, the criterion for the correct setting of the ignition timing without the use of instruments will be detonation knocks and engine power, while for diesel engines - shaking, smoke and knocks in the engine.
It has already been mentioned above that most injection pump problems are due to all sorts of leaks and leaks. For example, the plunger has worn out, a leak has occurred, so it does not create pressure. And if you replace the fuel with a thicker one? Then the increased gaps in the mating parts, as it were, will become smaller. And the injection pump will work as if it had no wear and tear. Making fuel thick is very easy. Add, as mentioned above, any engine oil to it. Of course, you don’t want to drive like that - it turns out to be too expensive fuel (and it’s troublesome to constantly prepare thick fuel). But to check the condition of the injection pump (as well as for the successful sale of a heavily used car in the market), this technique is useful. In the cold season, we, due to natural laziness, in order to make the fuel thick, simply cool the injection pump. For example, a car with a diesel engine comes with a complaint that it does not start well if it sits for five minutes, but the engine is still hot. We start this car (indeed, sometimes you have to turn the starter for 30 seconds), warm it up for another 10 minutes and turn it off. After that, we open the hood for her and cool the high-pressure fuel pump with snow. Within the same 5 minutes. If after this operation the engine starts better than the first time, we can already talk about heavy wear of the high-pressure fuel pump. Of course, both of these tricks (with thick fuel and with injection pump cooling) are not described in factory engine repair manuals and therefore cannot be considered very scientific. In those manuals, the volume of fuel supply at start-up is measured (there is such a parameter in the technical data - the volume of supply at a rotation speed of 200 rpm) and it is also easy to check this parameter at home. To do this, unscrew all the glow plugs and remove the tube from one nozzle. Then put the body of a disposable medical syringe on this tube and turn the engine with a starter. Naturally, counting the "zilch". 200 "zilch" is, of course, a lot. 50 is enough, and then compare the result with the technical data. In this case, we can assume that the injection volume at 200 rpm for all Japanese diesel engines, if they have the same volume, will be the same. If your engine size is slightly different, it is easy to make a proportion with the size of the diesel engine for which you have data. We also do all this when a hot engine does not start well, although, as follows from practice, everything can be checked even easier. Using snow and engine oil. In other words, if the operation of the injection pump with thick fuel becomes more acceptable, the injection volume should be checked. It is better, of course, to do all this at the stand (there you can check all the operating modes of the high-pressure fuel pump), but in the start mode (i.e. at 200 rpm), the check can also be done in the garage.
So, if the diesel engine has shaking in the region of 1500 - 2000 rpm, accompanied by the same blue color of the exhaust gases, it is necessary to repair the fuel system. And in particular, to make fuel injection earlier. To do this, in the simplest case, you need to turn the injection pump to an earlier injection.
Kornienko Sergey, Vladivostok, diagnostician
© Legion-Avtodata
The topic is a utopia, the sections of specialized forums are devoted to the problems of setting up the fuel.
Look for experience, advice, other people's practice there: Dieselmastera.ru, dieselirk.ru. Beginner + "hackneyed" topic, experienced people are tired of poking everyone's nose in the right direction, so if your enthusiasm for self-repair and tuning fades away, then the topic will soon sink and become garbage in the forum archives.
You need to adjust the angle as stated in the title of the topic with a micrometer, but these are far from all the settings with regards to the angle, it changes from idle to idle, then to maximum, and between times under load (pedals). I think you understand how capacious the title of your topic is. People with extensive experience indulge in strobe lights ... In general, the topic is the tip of the iceberg, either conquer it or ask the moderators to delete it).
They are right about the exhaust: a smelly, caustic-bitter and at the same time a sonorous (hard) sound like from KAMAZ early ignition,
Smoky sweetish from a bakery/deep fryer and soft/quiet engine running later. These observations are made on serviceable tuned injectors. The lower the opening pressure in the injectors, the softer the engine, it must be taken into account when tuning by ear.
At idle, smelling the pipe is inconspicuous, it is necessary to move above 50-60 km / h by slightly opening the rear window and pulling the front halfway into the cabin.
If the flow rate, in your opinion, is within reasonable limits - turn only the angle of the pump housing, having measured the initial position, at 2LT it is convenient to measure between the inlet and the booster housing, I have 4 mm, moving it back by 1 mm (measure with drill shanks) the angle measured by a micrometer changes by 0.06 mm , those 3..4 mm back and forth in your case is enough. Move back - later, move to the intake - early.
Playing with this setting only benefits one type of fuel. But you need to adjust by micrometer and fill a new risk. This is the starting point of a long and thorny path called the topic.
Thoroughbred fuel (euro) is sonorous and torquey, cheap or called "according to GOST" at truck stops - soft and sluggish.
These observations should be taken into account when tuning on the go by ear.
In order for the car to drive briskly and at the same time economically, it is first necessary to adjust the advance piston assembly, the one that is across the pump at the bottom of it. If you find a way to set up, consider half the victory. According to a respected diesel mechanic, a device for measuring the stroke of this piston is "an extremely useful thing." The internal pressure and the lead angle are directly related, apart from the load corrector, using an extremely useful thing, you must also have a pressure gauge with a device.
The motor quickly heats up this early ignition, but only if connected with it. In the summer, too, I drove miles and is ready to bake pies. In winter, it's completely different.
It works loudly on a cold one - this is from "normal" to "correct" and if it works noticeably softer on a running one and at the same time the revolutions are added during warm-up, then it's very good. The main thing in this node is that when the node is warmed up, it does not make adjustments to the advance angle - insert a screwdriver into the bracket on the axis of the springs and leaning on the central nut on the working pull forward to the radiator as soon as the shaft starts turning by hand, feel if there are any jolts, if there is a move (angle) before the jolts start, then leave it alone, if you feel jolts as soon as you make an effort, then you need to adjust it so that there is this free play / angle. A detailed murky and ultimately useless description of the setting for the layman is in the repair book.
With coming!
Here is the same problem I have drawn related to this topic.
I didn’t have enough experience, intelligence, etc., and I took off my equipment without putting a mark, and I put it in without looking, in general, anyhow.
(I gave it and the injectors for maintenance and tuning to diesel specialists)
Well, respectively, it started up haphazardly, barely, or rather.
Now it sits under the windows and does not start at all.
You twist - it seizes every other time and does not develop momentum.
The question is minimal: how to set up, Schaub to get to diesel engines (about 100 km)?
As long as it's not too cold
In the mirror it is clear that the risks on the injection pump and the body do not match,
BUT, it seems that the high-pressure fuel pump is no longer native.
Injection advance angle (IDA) and load in a diesel engine
(Note: this article is general knowledge and is not tied to any car brand)
It is strange to hear the opinion of a specialist, diagnostician, repairman that the injection advance angle in a diesel engine during its operation changes only depending on the speed of its crankshaft.
Undoubtedly, the crankshaft speed is one of the main parameters (characteristics) taken into account when organizing the combustion of the air-fuel mixture in the combustion chamber of both diesel and gasoline engines.
The amount of working fluid in the engine combustion chamber and its temperature depend on the crankshaft speed - the speed of the piston in the engine cylinder.
As crankshaft speed increases, the absolute durations of ignition delays (in milliseconds) decrease, but the relative durations in degrees of crankshaft revolution increase. Do not forget about such a moment as injection delay (the time between the start of fuel supply by the pump and fuel injection by the nozzle into the combustion chamber).
THE HIGHER THE ROTATION SPEED OF THE CRANKSHAFT, THE EARLIER IT IS NECESSARY TO INJECT FUEL INTO THE COMBUSTION CHAMBER AND vice versa.
Is it possible, when organizing combustion in the cylinders of a diesel engine, to confine oneself to adjusting the UOV according to the frequency of rotation of the crankshaft? Or is there something else that needs our attention?
Attention is required to the features of mixture formation and combustion in the combustion chamber of a diesel engine.
First of all, diesel refers to engines with internal mixture formation and fuel injection at the end of the compression stroke. Only 1 - 3 ms or 12 - 25 ° is allocated for mixture formation in terms of the angle of rotation of the engine crankshaft. This is 20 - 30 less than in engines with external and internal (injection in the intake stroke) mixture formation (most gasoline engines operate on homogeneous - homogeneous air-fuel mixtures).
The diesel engine is capable of running on lean mixtures with an excess air ratio at idle and at zero load = 10. The value for supercharged diesel engines at full load is in the range .. = 1.15 - 2.0. That is, the composition of the air-fuel mixture varies from very lean to lean.
Due to the heterogeneous (heterogeneous) composition of the air-fuel mixture (FA) in the combustion chamber of a diesel engine, there are areas with a rich and lean mixture, areas where there is only air or only diesel fuel. And, of course, there are areas of air-fuel mixture (FA) with a stoichiometric composition that are so necessary for timely ignition. That is a whole set of compositions of mixtures.
These conditions are valid both for engines with separate combustion chambers and for diesel engines with direct (direct) injection. It is the heterogeneous composition of the air-fuel mixture (FA) that allows the diesel engine to operate on lean mixtures.
On the other hand, the same inhomogeneous mixture composition (FA) at lower values 
is one of
The main disadvantages of diesel engines are the impossibility of complete and smokeless combustion of the air-fuel mixture (FA).
In addition to visual confirmation of what was written, I want to show you with the help of a diagram the main processes occurring in the combustion chamber of a diesel engine.
We are not talking about "explosions". We will talk about managed and controlled events that occur in time in parallel and sequentially. You need to see this chart and remember. Especially important are temperature changes in a diesel engine.
Figure 1 shows a typical diagram of changes in the engine cylinder of pressure p and average temperature t of gases as a function of angle φ, shows the nature of the change in time of the amount c of fuel supplied to the combustion chamber, its supply rate, active heat release coefficient X and heat release rate
For clarity and ease of perception, the diagram is drawn in expanded form. It must be viewed from left to right.
The piston moves to the top dead center, the pressure and temperature of the working fluid increase, and if there is no fuel injection at point 1, then when the piston moves from TDC to BDC, the pressure and temperature will decrease (indicated by a dotted line).
The fuel supply starts at point 1, at point 2 the first flames appear.
This period is called ignition delay and is characterized by the fact that the piston approaches TDC, the volume of the combustion chamber decreases, the temperature and pressure increase.
Rice. one
The amount of fuel st during this period is supplied insignificant, but at a high speed
The temperature in the combustion chamber (due to injection) decreases somewhat, and, accordingly, the pressure of the compressed air due to the heat spent on heating and evaporating the fuel.
From point 2 to point 3 - rapid combustion phase
It is characterized by the fact that the piston "passes" TDC, that is, the volume of the combustion chamber first decreases and then begins to increase.
The pressure during the movement of the piston from TDC reaches its maximum values, the temperature continues to rise. This period characterizes the "rigidity" of the combustion process in a diesel engine.
During this period, the main amount of fuel st is injected into the combustion chamber at the maximum possible speed. The rate of heat release increases sharply and reaches maximum values, and then begins to decrease. The active heat release coefficient X increases.
From point 3 to point 4 - slow burning phase
It is characterized by the fact that the piston moves from TDC to BDC, the volume of the combustion chamber increases. The pressure p of expanding gases decreases, and their temperature t reaches a maximum.
In this phase, fuel injection ends.
At the end of the slow combustion phase, there is a slight increase in the heat release rate associated with additional charge turbulence at the beginning of the downward stroke of the piston. The active heat release coefficient X increases.
From point 4 to the opening of the exhaust valve - the afterburn phase
It is characterized by the fact that the piston moves to the BDC - the volume of the combustion chamber increases, pressure and temperature decrease. The active heat release coefficient X stabilizes (the active heat release coefficient X characterizes the relationship between combustion processes and the use of the released heat - see special literature).
Combustion is a complex physical and chemical process that takes place in the gas phase. That is, first, liquid fuel must turn into steam, and then, as a result of chemical reactions, turn into a combustible mixture capable of performing mechanical work during combustion.
Liquid fuel injected into the combustion chamber breaks up into small droplets, spreads over it, heats up and evaporates. This is the essence of physical processes, and they proceed with the absorption of heat.
Oxidation processes have a multistage nature and are chain. As a result of chemical reactions (they proceed with the release of heat), a number of active intermediate chemical products (peroxides, aldehydes, alcohols, etc.) are formed that contribute to the further course of reactions.
Self-ignition is the end result of the development of these reactions.
The true sequence of elementary stages in the reactions of oxidation and combustion of motor fuels has not yet been fully studied, however, the dependence of their rates on temperature and pressure is characteristic of most chemical reactions.
The foregoing does not mean at all that physical and chemical processes are carried out sequentially. Everything happens almost simultaneously. The chemical component of the combustion process is somewhat behind due to the fact that at first, liquid fuel must nevertheless appear in the combustion chamber. Smaller droplets evaporate first. As a rule, these small droplets are grouped along the edges of the jet of fuel injected by the injector. The dynamics of the development of the fuel flame in the mechanical system is such that it cannot instantly occupy the volume of the combustion chamber in the engine cylinder; first, a small amount of high-pressure fuel is injected into the cylinder. This is facilitated by the law of fuel supply (each phase of combustion has its own amount of fuel), expressed constructively in the details of mechanical injection systems. Diesel fuel injection in these systems is carried out continuously.
In distribution injection pumps with solenoid valves, fuel pre-injection is possible. Passenger car injectors provide pre-injection by means of a hydromechanical drive.
Battery diesel fuel injection systems compare favorably with all previous systems in that, in addition to the preliminary and main injections, they also provide additional ones. Unlike the two-stage injection previously used on some brands of cars, in conditions of continuous fuel supply in battery systems, the preliminary injection is separate.
But now is not about that.
So, a preliminary amount of fuel is injected at high speed into a heated dense gaseous medium, collapses and evaporates. Possessing a small kinetic energy, this small (1-4 mm 3) amount of fuel is not able to break through dense air and remains in the area of \u200b\u200bthe nozzle and glow plug. In the process of mixture formation, zones are always formed, where X = 0.85 ... 0.9. These zones serve as ignition centers for the surrounding leaner mixture.
By the time of the main fuel injection, the fuel previously injected into the combustion chamber is already ready to ignite and ignites. In the combustion chamber, the pressure and temperature rise sharply, which contributes to a significant reduction in the ignition delay of the main injection. Diesel fuel under high pressure during the main injection, having greater kinetic energy, breaks through an increasingly denser (already burning) gaseous medium to all areas of the combustion chamber remote from the nozzle.
The movement of air, given by the design of the intake manifold, by the movement of the piston in the compression stroke is greatly enhanced by expanding combustion products moving from the ignition points in different directions. Air masses in turbulent motion, pulsating gas flows are pierced by fuel torches (there can be from 4 to 10 holes in the atomizer; in most cases - 6h-8.) Under these conditions, the fuel that continues to be injected burns out almost instantly.
The pressure in the cylinder increases in a timely manner, smoothly and without noise.
BURN RATE OF LIQUID FUEL IS DETERMINED
THE RATES OF ITS EVAPORATION AND THE MIXING OF THE PRODUCED VAPOR WITH AIR
This is true for internal combustion engines running on light and heavy liquid fuels.
Injection of fuel into the combustion chamber of a diesel engine entails
temperature drop (fuel evaporation is accompanied by heat absorption).
The amount of temperature drop depends on the load.
This is especially noticeable during transient conditions associated with an increase in load.
On page 58 of the first edition of the BOSCH book “Diesel Engine Control Systems” (translated from the German publishing house “Za Rulem”, 2004), the characteristics of the injection start time are shown depending on the crankshaft speed and the load on the engine of a passenger car at a cold start and operating temperature .
1) cold start (<0 °С);
Rice. 2It is easy to see that at a crankshaft speed of 1000 rpm at partial loads (3) and full load (2) it requires its own, corresponding to the load, fuel level. That is, a larger amount of fuel must be injected into the combustion chamber of the engine earlier in order to “keep” the pressure peak of the gases expanding during combustion at TDC.
Cold starting a diesel engine is not much different from a gasoline engine. The lack of heat in the combustion chamber and, in connection with this, poor conditions for the evaporation of diesel fuel are compensated by its greater cyclic supply. A larger amount of fuel (the desired vapor concentration due to increased fuel supply), its earlier injection (1) and air heating systems are regular functions of all cold start acceleration systems without exception.
Thus, WHEN FUEL INJECTION DURING THE COMPRESSION STROKE, TEMPERATURE CHANGES ARE OBSERVED IN THE COMBUSTION CHAMBER.
There is a need to adjust the DVR of diesel fuel.
When testing high-pressure fuel pumps on the stand, it is necessary to use tables or maps of specified control parameters. They indicate the conditions under which the tested injection pump must comply with the tabular data.
FUNCTIONS OF THE VE TYPE INJECTION THAT ARE A POINT OF ATTENTION
Serviceability of the elements responsible for high pressure;
Serviceability of the elements responsible for the pressure in the injection pump;
Serviceability of the elements of the advance machine;
pump performance;
The operation of the speed controller.
These figures are considered at given speeds and full load.
In 1978, a switchable load-dependent start-of-feed control device appeared on the VE-type injection pump.
Later, correctors of the LFB type appeared (a device for changing the moment the fuel supply starts, depending on the load). These devices are designed to correct the start of fuel supply depending on the load in order to reduce noise and especially exhaust emissions.
What does the word correction mean? Correction - making adjustments to the operation of measuring instruments, regulators, etc., depending on changes in their operating conditions.
When checking the injection pump, load correctors and other ennobling devices are checked.
Interesting results can be obtained by comparing the pressure in the VE type injection pump with and without load corrector at minimum idle speed. So, with a corrector, the pressure in the injection pump at idle is -1.5h-2.0 bar, and without a corrector - 2.5h-3.8 bar. That is, the piston of the high-pressure fuel pump advance automatic device without a corrector is already in the “earlier” position with the expectation of increasing the cyclic fuel supply.
You know that the pressure in the high pressure fuel pump type VE affects the change in the SVR over time. The higher the shaft speed, the higher the pressure in the fuel pump and the greater the distance the hydraulic piston of the automatic advance moves - earlier injection.
BASIC FUNCTIONS OF THE CORRECTOR
Pressure increase in high pressure fuel pump at start-up;
Increasing pressure in high pressure fuel pump with increasing load;
Decrease in pressure in the injection pump with a decrease in load.
The pressure in the injection pump varies within 1 n-2 bar.
It allowed:
Provide earlier injection of diesel fuel at start-up (thereby improving it);
Reduce the pressure in the injection pump at idle and, as a result, reduce the noise of the diesel engine in this mode;
Vary between "earlier" or "later" positions depending on the load. With decreasing load (from full to partial) and with the position of the fuel supply pedal unchanged, the start of supply is shifted to the “later” position. With an increase in load - to the "earlier" position. And, as a result, the engine becomes softer, and the toxicity of the exhaust gases decreases in partial load mode.
I confess honestly that until the fourth meeting of diagnosticians, I did not think about the features of the device for controlling the advance control by injection of in-line high-pressure fuel pumps. It seemed natural to me to understand that the fuel injection advance angle depends on many factors. Including, on the engine speed and load. When looking more closely at the issue of regulation of VRM, the question arose: how exactly is this regulation carried out? Indeed, in the design of an in-line injection pump, only a speed controller is provided. The device for adjusting the advance angle by injection is placed outside the injection pump.
So about the clutch ... The clutch is like a clutch, nothing special: springs, weights. It consists of two halves moving relative to each other with one center (engine OM 602.911). And it works simply: the higher the crankshaft speed, the farther from the center of the coupling the loads move and turn the second half of the coupling (together with the injection pump shaft) in the direction of rotation - earlier fuel injection.
I thought about the corrector, but I did not find a place convenient for its installation in this clutch. This is a difficult event in an in-line high-pressure fuel pump - to organize the correction of the UOV according to the load. But with the advent of an in-line injection pump with an additional (regulating) bushing, this has become a reality.
“... With the help of electronics, it becomes possible to introduce an additional (in comparison with the standard injection pump) correction of the diesel operation regulation. ..." (p. 177, First edition of the BOSCH book "Diesel Engine Control Systems", translated from the German publishing house "Behind the wheel", 2004).
With these examples, I want to say that structurally, in the elements of simple mechanical high-pressure fuel pumps responsible for the regulation of the HPV in dynamics, temperature fluctuations in the engine combustion chamber, depending on the amount of fuel injected into it, are taken into account. At one time, such solutions were quite suitable for car manufacturers and buyers.
Time passes - everything changes.
I believe that it is necessary to consider all the processes occurring in the engine combustion chamber, depending on the rotational speed, separately from the processes occurring when the load changes.
To understand the essence of what is happening. You cannot separate these processes.
A change in the amount of the working fluid entails a change in the speed of the crankshaft. Even at no load.
On page 58 of the First Edition of the BOSCH book “Diesel Engine Control Systems”, translated from the German publishing house “Za Rulem”, 2004, it is said: “... The optimal injection advance angles vary depending on the engine load, which requires their regulation. The required values are set separately for each type of engine and form a performance field that determines the injection start time depending on the engine load, crankshaft speed and coolant temperature ... ".
Thirty-eight years ago, it was said about adjusting the ROV depending on the engine speed and load. The possibilities for organizing the optimal combustion of the air-fuel mixture in the engine cylinders at that time were completely different than today.
Vladimir Belonosov
The ignition system of the engine provides, with the help of a spark, the timely ignition of the mixture of fuel and air that enters the combustion chamber. However, this is necessary for gasoline cars, with diesel cars everything is different. In them, air and fuel enter the cylinders separately, and the air is highly compressed and accordingly heated (the temperature can reach 700 C), thus self-ignition occurs. The significance of this system for both types of motors is briefly clear, but it will not be easy to describe its installation in a laconic way, so we will devote our article to it.
Engine ignition system - the difference between a "diesel" and a gasoline engine
Due to these differences in the process of ignition of gasoline and diesel fuel in the engine, one can also note the difference in the structure of ignition. It is obvious at least that there is no such system as in a gasoline car, consisting of a breaker-distributor, a switch or pulse sensors, in a diesel car. However, in winter it is sometimes difficult to succeed, due to the fact that the air is too cold, so a special preheating system is installed to increase the temperature of the air in the combustion chamber.
We can say that setting the ignition on a diesel engine is nothing more than choosing the fuel injection advance angle. And this is achieved by adjusting the position of the piston, at the time of injection of the "diesel" into the cylinder. This is very important, because if the injection angle is chosen incorrectly, the injection will be untimely, and, as a result, the fuel will not burn to the end. And this will negatively affect the coordinated operation of the cylinders.
Having made a minor mistake, just one degree, you can provoke the failure of the entire power unit, which will require a major overhaul.
Diesel engine ignition system - device and adjustment principle
Summing up, we can say that the ignition system of a diesel engine includes a high pressure pump (high pressure fuel pump), through which fuel is introduced into the combustion chamber. Modern motorists find efficiency and fuel economy in such a system device, so diesel engines are becoming more popular. It is because of the increasing number of users that we decided to reveal the secrets of maintaining the described ignition system.
If the car has a diesel power unit with mechanical fuel equipment, then the injection advance angle can be adjusted by turning the pump around its axis. You can also rotate the toothed pulley relative to the hub. If the injection pump and the toothed pulley are rigidly fixed, then the adjustment occurs only due to the angular shift of the camshaft toothed pulley. But it's all lyrics, it's time to move on to action.
Adjusting the ignition of a diesel engine - an instruction for decisive
Diesel engine can be produced by yourself. First you need to lift the hood cover and fix it on the support column. On the top left of the back of the engine, you need to find a flywheel (massive wheel), on the housing of which a mechanical device is located. The stem of this device must first be lifted and turned 90 degrees, then lowered into the slot located on the body.
Now remove the mudguard, for this you need to unscrew two bolts on the flywheel housing with a 17 mm wrench (it's easier to get to this place from under the car). Insert a metal rod into the flywheel hole through the slot in the casing and turn the engine crankshaft. You need to direct it from left to right until its course is blocked by the locking rod from above.
Now is the time to look at the fuel pump drive shaft, it is located on top of the collapse of the cylinder block (the axis from which the cylinder rows diverge). If the setting scale of the drive coupling (the flange that transmits rotations from the drive shaft) of the high pressure fuel pump is turned up, then in this case, the mark on the fuel pump flange should be aligned with the zero mark of the drive and tighten the two fixing bolts. If the setting scale of the drive clutch is not turned up, then it will be necessary to lift the stopper, and turn the engine crankshaft one turn, and then all of the above steps must be repeated in the same order.
Once the drive clutch bolts are tightened, you need to lift the flywheel stopper up, turn it 90 degrees and lower it into the groove. On the flywheel housing from below, you can return the mudguard to its place (bolted). Now it's time to close the hood of the car, the work is finished. It remains to start the car and check the accuracy of the system.
