Injection advance (Diesel). Injection advance angle and fuel delivery advance angle Diesel fuel injection setting
The most important criteria for optimizing diesel engine performance are:
- low toxicity exhaust gases;
- low noise from the combustion process;
- low specific fuel consumption.
The moment at which the injection pump begins to supply fuel is called the start of supply (or closing of the channel). This point in time is selected in accordance with the ignition delay period (or simply the ignition delay). They are variable parameters that depend on the specific operating mode. The injection delay period is defined as the period between the start of delivery and the start of injection, and the ignition delay period is defined as the period between the start of injection and the start of combustion. The start of injection is defined as the angle of rotation crankshaft in the TDC region, in which the injector injects fuel into the combustion chamber.
The onset of combustion is defined as the moment of ignition fuel-air mixture, which can be influenced by the start of injection. At injection pump adjustment The start of delivery (closing of the channel) depending on the number of revolutions is best done using an injection advance device.
Purpose of injection advance device
Due to the fact that the injection advance device directly changes the moment of the start of delivery, it can be defined as a regulator of the start of delivery. The injection advance device (also called the injection advance clutch) of the eccentric type converts the driving torque supplied to the injection pump, at the same time, performing its regulating functions. The torque required by the injection pump depends on the size of the pump, the number of piston pairs, the amount of fuel injected, the injection pressure, the diameter of the plunger and the shape of the cam. The fact that the drive torque has a direct effect on the injection advance characteristics must be taken into account in the design along with the possible power output.
Rice. Cylinder pressure: A. Beginning of injection; B. Start of combustion; C. Ignition delay. 1. Intake stroke; 2. Compression stroke; 3. Working stroke; 4. Release stroke OT-VMT, UT-NMT; 5. Pressure in the cylinder, bar; 6. Piston position.
The design of the injection advance device
The injection advance device for the in-line injection pump is mounted directly on the end of the injection pump camshaft. Basically, open-type and closed-type injection advance devices differ.
The closed type injection advance device has its own lubricating oil reservoir, which makes the device independent of the engine lubrication system. The open design is connected directly to the engine lubrication system. The body of the device is attached with screws to the gear, and the compensating and adjusting eccentrics are installed in the body so that they turn freely. Compensating and adjusting eccentrics are guided by a pin, which is rigidly connected to the body. In addition to being cheaper, the "open" type has the advantage of requiring less space and lubricating more efficiently.
The principle of operation of the injection advance device
The injection advance device is driven by a toothed gear, which is installed in the engine timing drive housing. The connection between the input and the output for the drive (hub) is made through the interlocking pairs of eccentric elements.
The largest of them, the adjusting eccentric elements (4) are located in the holes in the locking disc (8), which, in turn, is bolted to the drive element (1). The compensating eccentric elements (5) are installed in the adjusting eccentric elements (4) and guided by them and the bolt into the hubs (6). On the other hand, the hub bolt is directly connected to the hub (2). The weights (7) are connected to the adjusting eccentric element and are held in their original positions by springs with variable stiffness.
Rice. a) in the initial position; b) low rpm; c) Average turnovers; d) High speed end position; a is the injection advance angle.
Injection advance device dimensions
The size of the injection advance device, determined by the outer diameter and depth, in turn determines the weight of the installed weights, the distance between the centers of gravity and possible move weights. These three factors also determine the power output and application.
Rice. M size injection pump
Rice. 1. Discharge valve; 2. Sleeve; 7. Cam shaft; 8. Cam.
The M size injection pump is the smallest pump in the range of in-line injection pumps. It has a light alloy body and is flange mounted to the engine. Access to the inside of the pump is possible after removal of the base plate and side cover, and therefore the size M pump is defined as an open injection pump. Peak injection pressure is limited to 400 bar.
After removing the side cover of the pump, the amount of fuel supplied by the plunger pairs can be adjusted and set at the same level. Individual adjustment is carried out by moving the clamping parts on the control rod (4).
During operation, the installation of the pump plungers and, together with them, the amount of fuel supplied is regulated by the control rod in the range determined by the design of the pump. The control rod of the injection pump of size M is a round steel rod with a plane on which clamping elements (5) with grooves are installed. The levers (3) are tightly connected to each control sleeve, and the rod riveted to its end enters the groove of the control rod clamping element. This design is known as lever control.
The injection pump plungers are in direct contact with the roller tappets (6), and the adjustment of the preliminary stroke is carried out by selecting rollers with the appropriate diameters for the pusher.
Lubrication of the injection pump size M is carried out by normal oil supply from the engine. The M size injection pump is available with 4.5 or 6 piston pairs (4-, 5- or 6-cylinder injection pump) and is designed for diesel fuel only.
Rice. Injection pump size A
In-line A size injection pumps with a large delivery range follow directly after the M size injection pump. This pump also has a light alloy casing and can be flanged or frame mounted to the engine. Type A injection pump also has an "open" design, and the pump liners (2) are inserted directly from the top into the aluminum housing, with the discharge valve (1) assembly pressed into the injection pump housing using a valve holder. The sealing pressure, which is much greater than the hydraulic supply pressure, must be absorbed by the injection pump housing. For this reason, the peak injection pressure is limited to 600 bar.
Unlike the Type M injection pump, the Type A injection pump is equipped with an adjusting screw (with locknut) (7) in each roller tappet (8) to set the prestroke.
To adjust the amount of fuel supplied by means of the control rack (4), the injection pump type A, in contrast to the injection pump type M, is equipped with gear control instead of lever control. The toothed segment, clamped on the control sleeve (5) of the plunger, is engaged with the control rack and in order to adjust the plunger pairs to the same feed, the fixing screws must be released, and the control sleeve must be rotated relative to the toothed segment and, thus, relative to the control rail.
All adjustment work on this type of injection pump must be carried out on the pump installed on the stand and with an open casing. Like the M injection pump, the Type A injection pump has a spring-loaded side cover that must be removed to gain access to the inside of the injection pump.
For lubrication, the injection pump is connected to the engine lubrication system. High pressure fuel pump type A is available in versions with up to 12 cylinders, and, unlike high pressure fuel pump type M, it is suitable for operation on various types of fuels (not just diesel).
Rice. WM size injection pump
The MW inline injection pump has been designed to meet the need for increased pressure. The MW injection pump is a closed type in-line injection pump and its peak injection pressure is limited to 900 bar. It also has a light alloy body and is attached to the engine with a frame, flat base or flange.
The design of the MW injection pump differs markedly from the design of the A and M injection pumps. The main difference is the use of a plunger pair that includes a sleeve (3), a pressure valve and a pressure valve holder. It is assembled outside the engine and inserted from above into the injection pump housing. On the MW injection pump, the pressure valve holder is screwed directly into the sleeve, which protrudes upwards. The pre-stroke is adjusted using shims that are inserted between the body and sleeve with valve assembly. Adjustment of the uniform supply of individual plunger pairs is carried out outside the injection pump by turning the plunger pairs. Plunger pair mounting flanges (1) are provided with grooves for this purpose.
Rice. 1. Mounting flange for a plunger pair; 2. Discharge valve; 3. Sleeve; 4. Plunger; 5. Control rail; 6. Control sleeve; 7. Roller pusher; 8. Cam shaft; 9. Cam.
The position of the injection pump plunger remains unchanged when the sleeve assembly with the discharge valve (2) is rotated. The MW injection pump is available in versions with up to 8 sleeves (8-cylinder) and is suitable for various mounting methods. It runs on diesel fuel and is lubricated through the engine's lubrication system.
Rice. P-size injection pump
Rice. 1. Discharge valve; 2. Sleeve; 3. Thrust control; 4. Control sleeve; 5. Roller pusher; 6. Cam shaft; 7. Cam.
The in-line injection pump of size (type) P was also designed to provide high peak injection pressure. Like the MW injection pump, it is a closed type pump and is attached to the engine with a base or flange. In the case of P-type injection pumps designed for a peak injection pressure of 850 bar, the sleeve (2) is inserted into the flange bushing, which is already threaded for the delivery valve holder (1). With this sleeve installation version, the sealing force does not load the pump housing. The pre-stroke is adjusted in the same way as for the MW injection pump.
In-line injection pumps, designed for low injection pressure, use the usual filling of the fuel line. In this case, the fuel passes fuel lines individual sleeves one after the other and in the direction of the longitudinal axis of the injection pump. Fuel enters the line and exits through the fuel return system.
Taking the P8000 version of the P injection pump as an example, which is designed for injection pressures up to 1150 bar (injection pump side), this filling method can lead to excessive fuel temperature differences (up to 40°C) inside the injection pump between the first and last sleeves. Since the energy density of a fuel decreases with an increase in its temperature and, as a result, with an increase in volume, this will lead to the injection of different amounts of energy into the combustion chambers of the engine. In this regard, such injection pumps use transverse filling, i.e. a method in which the fuel lines of individual sleeves are separated from each other by means of throttling holes. This means that they can be filled parallel to each other (at right angles to the longitudinal axis of the injection pump under almost identical temperature conditions).
This injection pump is also connected to the engine lubrication system for lubrication. High pressure fuel pump type P is also available in versions with up to 12 liners (cylinders) and is suitable for operation on both diesel and other fuels.
From gasoline is the principle of ignition of diesel fuel. Ignition of the fuel-air mixture in diesel engine realized by self-ignition of diesel fuel from contact with pre-compressed and heated air in the cylinders as a result of such compression.
Setting the ignition on a diesel engine involves changing the fuel injection advance angle, which is delivered at a well-defined moment at the end of the compression stroke. If the angle is set differently from optimal parameters, then the fuel injection will be untimely. The result will be incomplete combustion of the mixture in the cylinders, which causes a devastating imbalance in the operation of the engine.
It should be remembered that even slight deviations in the fuel injection angle setting can lead to serious damage to the diesel engine.
It turns out that the ignition system of a diesel engine should be understood as the most important element of the power unit power system -. In most diesel engines, it is this device, in combination with diesel injectors, that is responsible for the timely metered supply of diesel fuel to the engine cylinders.
Read in this article
How to set the injection advance angle on a diesel
The need to install the ignition on a diesel engine with your own hands often arises in such cases:
- diesel ignition must be corrected in parallel with the replacement of the timing belt;
- after dismantling the injection pump, it is not possible to install a pulley fuel pump according to special labels;
One of the recommendations before starting any work related to the analysis of the diesel fuel equipment is the urgent need to clearly mark and refresh all marks. To do this, it is enough to apply small strokes with paint or a high-quality marker. This will facilitate subsequent reassembly and installation of the injection pump pulley, which will automatically eliminate or minimize potential ignition failures.
There are several ways to set the ignition on a diesel engine:
- strictly by labels (subject to availability);
- selection method empirically;
Setting the angle by marks
The first way to independently set the ignition angle of a diesel engine (the moment of injection of diesel fuel) by marks involves the displacement of the fuel pump. This method is suitable for diesel internal combustion engines in which mechanical fuel equipment is installed.
The injection advance angle is adjusted by turning the injection pump around the axis. A method is also possible when the camshaft pulley rotates in relation to the hub. This method is suitable for those designs in which the pump and pulley do not have a rigid mount.
- To adjust the ignition on a diesel engine with your own hands, you need to turn to the rear of the internal combustion engine and get to, if necessary, dismantle the protective cover from it.
- Next, you need to find a stopper on the flywheel, which falls into a special slot.
- After that, the flywheel must be turned manually (using a key or other device). Cranking the flywheel means that the crankshaft of the internal combustion engine is rotating. You need to twist clockwise until the moment when the upper stopper-latch works.
- Then we pay attention to the injection pump drive shaft. It is possible that the scale on the drive clutch, through which the rotation is transmitted, occupies the upper position. In this case, the mark on the injection pump flange is aligned with the zero mark on the drive.
- After the marks are aligned, the fixing bolts can be tightened. A setting dial on the drive clutch that is not up means that the flywheel stopper must be lifted, after which the engine crankshaft rotates one revolution again. Next, the position of the scale is again controlled.
- After tightening the bolts of the drive clutch, the stopper on the flywheel is lifted, the crankshaft is rotated 90 °, then the stopper is placed in the groove.
The final step is to install the flywheel protection in place and tighten the mounting bolts. Next, the engine is started, its work is analyzed. The unit at idle should work smoothly and smoothly, without failures and twitches. Rigid diesel operation, accompanied by, is unacceptable.
Next, you need to check the correct setting in motion, avoiding serious loads. Warm up the engine to operating temperature and evaluate acceptability power plant, reactions to pressing the gas pedal. It is also necessary to monitor the color of the exhaust gases, since the late fuel injection advance angle will be followed.
Choosing the right injection angle
You can experimentally adjust the ignition angle on a diesel engine as follows:
- After installing the pulley, attempts are made to start a diesel engine. If the engine does not start, then the injection pump pulley is rotated relative to the belt by several teeth (2-4). Then they try to start the engine again.
- When the motor starts up after the manipulations described above, evaluate its work. The presence of obvious detonation knocks means that the fuel pump pulley must be turned a tooth or two in the opposite direction to rotation. The appearance of thick gray smoke may indicate a late injection angle. In such a situation, the pump pulley turns one tooth in the direction of rotation.
The lack of positive changes in the operation of the motor will require the rotation of the fuel pump around the axis. By such cranking, it is necessary to bring the motor to the optimum operating mode. The best option the diesel engine will work in such a mode when there is very little left before the start of detonation. The detonation knocks themselves are clearly visible in the sound of the internal combustion engine.
The second available method involves the following steps:
- The high-pressure pipe is dismantled from the nozzle of the first cylinder. A transparent plastic hose must be tightly put on the removed tube and placed in a vertical position.
- After that, you can turn on the ignition and turn the pump pulley. The pulley rotates as gently, slowly and accurately as possible.
- Next, you need to monitor the fuel level in the tube and identify the upper limit.
- Noticing when the level of diesel fuel in the tube is the highest, it is necessary to make a mark on the pulley.
- Then, according to the marks, you need to set the crankshaft and camshaft engine.
After starting, the operation of the engine is evaluated. If an early or late fuel injection angle is determined, the tuning operation must be repeated.
Read also
Signs for determining the correctness of the set ignition timing. The consequences of an incorrectly configured UOZ, ways to set the ignition.
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. 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 it gets dirty fuel filter, the plunger of the pressure reducing valve will stick open or the blades of the supply pump will sink (inside the injection pump). (FIG. 38, FIG. 39)
rice. 38 fig.39
Rice. 38. To fully check 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 when the engine is running, 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, as well as kerosene, almost does not contain heavy fractions, which provide lubrication of all rubbing parts), fuel with air and simply 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. While shaking out exhaust pipe there is blue smoke. 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 diesel engines, the piston-cylinder gap is very large and therefore they begin to work hard even at absolutely right angle injection advance. 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 advance the ignition 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 the 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 do all this when hot engine it doesn’t start well, although, as follows from practice, you can check everything even easier. Using snow and motor 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 blue color of the exhaust gases, it is necessary to repair 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 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 machines everything is different. In them, air and fuel enter the cylinders separately, and the air is highly compressed and heated accordingly (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 such a system as in petrol car, consisting of a breaker-distributor, a switch or impulse sensors, is not 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 in such a system device the efficiency and economy of fuel consumption, therefore 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 you can adjust the injection advance angle by turning the pump around its axis. You can also rotate the toothed pulley relative to the hub. If the injection pump and the gear pulley are rigidly fixed, then the adjustment occurs only due to the angular shift of the camshaft gear 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 casing with a 17 mm wrench (it's easier to get to this place from under the car). Insert a metal rod into the hole in the flywheel 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.
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.
P&G placement sponsor Related articles "How to set the injection timing on a diesel engine"
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...
1 0
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 connected 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 cover of the timing gears and the drive pulley of the fan drive: 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...
0 0
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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Registration: 07/07/2013
Address: Orel
Make: Jeep Cherokee, year of manufacture 1993, 4L, AW4 30-40LE, NP242J, and Hyundai Grace H-100 minibus, 1995, D4BX, des.
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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 the 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 imperative 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, auxiliary quantities are given for each motor (for example, the length of the arc of a circle drive pulley fan) 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 begins ...
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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. Everything you need to know Not a small amount modern cars they know how to drive a diesel engine 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 idling, the lead angle will be equal to 3 degrees, for 1000 revolutions 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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10
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 impulse sensors, in a diesel car. However, in winter it is sometimes difficult to start diesel engine, due to the fact that the air is too cold, therefore, 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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11
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, the 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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