The fuel supply system ensures fuel filtration and its uniform distribution over the engine cylinders in metered portions at strictly defined moments
The engine uses a split-type fuel supply system, consisting of a fuel tank, low-pressure fuel lines, coarse and fine fuel filters, fuel priming and priming pumps, a high-pressure fuel pump with a stop solenoid, high-pressure fuel lines, injectors, electromagnetic valve and pin candles of the electric torch device (EFD).
The fuel tank, the fuel coarse filter and the fuel priming pump must be installed on the product on which the engine is used, all other elements of the power system are installed directly on the engine.
Scheme of the engine fuel supply system is shown in Figure 1.
Fuel from the fuel tank 26 through the coarse filter 29 and the fuel priming pump 30 is supplied by the fuel priming pump 18, through the fuel pipe 13 to the fine filter 16.
From the fine filter, through the low-pressure fuel pipe 14, the fuel enters the high-pressure fuel pump 21, which, in accordance with the order of operation of the cylinders, distributes fuel through the high-pressure fuel lines 1-8 to the injectors 10.
Injectors inject fuel into the combustion chambers.
Excess fuel, and with it the air that has entered the system through the bypass valve 24 and valve 23, is discharged into the fuel tank.
Nozzle type 273 of closed design, with five spray holes and hydraulically controlled lifting of the needle of the sprayer, is shown in Figure 2.
All parts of the nozzle are assembled in the body 6. The body 1 of the atomizer, inside which there is a needle 12, is pressed with a nut 2 through a spacer 3.
The body and needle of the atomizer are a precision pair.
Angular fixation of the atomizer body relative to the spacer and the spacer relative to the nozzle body is carried out by pins 4.
Spring 11 exerts pressure on the upper end of the atomizer needle through rod 5.
The necessary tension of this spring is carried out by a set of adjusting washers 9, 10, installed between the spring and the end of the inner cavity of the nozzle body.
Fuel is supplied to the injector at high pressure through fitting 8 with a slotted filter 13 built into it, then through the channels of body 6, spacer 3 and atomizer body 1 - into the cavity between the atomizer body and needle 12 and, raising it, is injected into the cylinder engine.
The fuel that has leaked through the gap between the needle and the atomizer body is discharged through the channels in the nozzle body and drains into the tank through drain pipes 9 and 11, shown in Figure 42.
The nozzle is installed in the cylinder head, fixed with brackets, which are secured with a nut.
The butt end of the atomizer nut is sealed against gas breakthrough with a corrugated copper gasket.
O-ring 7 (picture 2) protects the cavity between the nozzle and the cylinder head from dust and liquids.
Checking and adjusting nozzles, as well as replacing nozzles, must be carried out in a specialized workshop.
It is forbidden to install injectors of other models, except those specified in the instructions, due to the possibility of engine failure.
The high-pressure fuel pump (Figure 3) is designed to supply strictly metered portions of high-pressure fuel to the engine cylinders at certain moments.
An injection pump model 337-20 with an all-mode regulator is installed on an automotive equipment engine.
An injection pump model 337-71 with a two-mode regulator is installed on the bus configuration engine.
The diameter of the injection pump plunger is -11 mm, the plunger stroke is -13 mm, the discharge valve is fungal, with a feather diameter of 7 mm without unloading.
Eight sections are installed in the injection pump housing 1, consisting of a housing 6, a plunger bushing 8, a plunger 7, a rotary bushing 4, a discharge valve 11 with a seat 10, a fitting 12 pressed against the plunger bushing.
The plunger reciprocates under the action of the shaft cam 46 and the pusher spring 3. The pusher 2 from turning in the body is fixed with a cracker 14.
The camshaft rotates in roller bearings 45.
The outer races of the bearings are installed in steel rings pressed into the pump housing. From axial movement, the camshaft is fixed by covers.
The tension of the camshaft bearings is regulated by gaskets 44 and should be 0.05 ... 0.15 mm.
To change the fuel supply, the plunger 7 is rotated with the help of a sleeve 4 connected through the axis of the leash to the rail 5 of the pump. The rail moves in guide bushings 40.
The holes for the guide bushings in the injection pump housing on the drive side are closed with plugs 39.
On the opposite side of the pump, on the back cover 20 of the regulator, there is a fuel supply corrector for charge air pressure 24.
At the front end of the housing, at the point where the fuel exits the pump, a bypass valve 38 is installed, which provides pressure in front of the inlet holes of the plungers at operating modes of 0.13 ... 0.19 MPa (1.3 ... 1.9 kgf/cm2).
The lubrication of the pump is circulation, under pressure from the general lubrication system of the engine.
Regulator of the frequency of rotation of the injection pump mod. 337-20 (Figure 4) all-mode, direct action, changes the amount of fuel supplied to the cylinders depending on the load, maintaining a given crankshaft speed.
The regulator is installed in the collapse of the injection pump housing. The drive gear of the regulator 16 (Figure 3) is installed on the cam shaft of the pump, the rotation of which is transmitted through rubber crackers 17.
The driven gear is made integral with the holder of 28 weights, rotating on two ball bearings.
When the holder rotates, the loads 31, swinging on the axes 29, diverge under the action of centrifugal forces and move the regulator clutch 32 through the thrust bearing 30, which, resting against the pin 34, in turn, moves the levers 2, 8 and 9 of the regulator (Figure 4), overcoming the force of the spring 5.
Lever 2 is connected through a pin to the right rail 3 of the fuel pump. The right rail through the rail lever 7 is connected to the left rail 11.
The operation of the speed controller is shown in Figure 5.
The regulator control lever 16 is rigidly connected to the lever 12. The regulator spring 13 is connected to the lever 12, and the starting spring 15 is connected to the levers 14 and 11.
During the operation of the regulator, the centrifugal forces of the weights are balanced by the force of the spring 13.
With an increase in the crankshaft speed, the loads, overcoming the resistance of the spring 13, move the levers 2, 4 and 9, and with them the injection pump rails - the fuel supply decreases.
When the crankshaft speed decreases, the centrifugal force of the loads decreases, and the levers with the injection pump rack move in the opposite direction under the action of the spring force - the fuel supply and the crankshaft speed increase.
When the lever 9 of the regulator rests against the bolt 6 and the crankshaft speed is less than 1800 min-1, the spring 10 of the direct corrector moves the pump rails (through levers 2 and 4) into
the direction of increasing the fuel supply, providing the required amount of maximum engine torque.
Spring 3 of the reverse corrector at a speed of less than 1400 min-1 moves the lever 4 with rails in the direction of reducing the fuel supply, limiting the maximum smoke of the exhaust gases of the engine.
The fuel supply is stopped by turning the lever 3 (Figure 6) to stop the engine until it stops against the bolt 5.
The lever is turned by the force of the spring built into the engine stop solenoid 6 when the holding winding of the electromagnet is disconnected from the power source (the key of the instrument switch and starter lock is in the fixed position "0").
At the same time, lever 3, having overcome the forces of springs 33 (Figure 3) and 5 (Figure 4), will turn levers 2,9 and 8 through pin 14, the rails will move until the fuel supply is completely cut off
When the key of the instrument and starter switch lock is turned to the fixed position "I", power is supplied to the holding winding of the stop solenoid, and when the key is further turned to the non-fixed position "II", power is supplied to the retracting winding of the electromagnet, the electromagnet rod, overcoming the force of its own spring, extends and releases lever 3 (Figure 6).
Lever 3 under the action of spring 33 (Figure 3) returns to its working position, and the starting spring 6 (Figure 4) through the rack lever 7 will return the injection pump racks to the position corresponding to the maximum and the fuel supply necessary to start the engine.
When the instrument and starter switch lock key is moved from the non-fixed position “II” to the fixed position “I”, the retracting winding of the electromagnet is disconnected from the power source and the stem of the stop solenoid remains in the working position only due to the holding winding.
Checking and adjusting the injection pump, as well as replacing the plunger pairs, sealing rings of the injection pump sections must be carried out in a specialized workshop by a qualified specialist.
It is STRICTLY PROHIBITED to install other models of injection pump on the engine 740.30-260 in order to avoid deterioration in the quality of the engines working process, an increase in toxicity and opacity of exhaust gases, as well as engine failure!
Fuel supply corrector based on charge air pressure (Figure 7).
The charge air pressure corrector reduces the fuel supply when the charge air pressure drops below 40...45 kPa (0.4...0.45 kgf/cm2), thereby engine protection and limiting exhaust smoke.
A piston 26 with a spool 2 is installed in the body of the corrector 1. The spring 27 acts on the piston, fixed by the plate 25 and the ring 3.
A stud 29 with a tip 31, which is the nominal stop in the regulator, is wrapped and locked with a nut 28 into the piston.
The tip is locked with a nut 30. The spool 2 is acted upon by a spring 7, the pretension of which can be changed by an adjusting screw 11.
Membrane body 8 is attached to corrector body 1 through gasket 4. Membrane assembly with stem (parts 24,16,17,23,22, 19, 18) is installed in it.
The membrane is clamped between the body 8 and the cover 21. In the body of the membrane 8 on the axis of the lever 13 there is a corrector lever 12, the rotation of which is limited by the adjusting screw 15.
Fuel corrector not direct action; when the charge air pressure changes in the membrane cavity, the position of the spool changes, which, in turn, determines the position of the corrector piston.
In the cavity "A" between the body of the corrector 1 and piston 26, oil is supplied under pressure from the engine lubrication system through a threaded hole and a 0.7 mm jet in the body of the corrector (not shown in the figure).
The piston under the action of this pressure, compressing the spring 27, moves to the left until the windows in the piston and spool open and the oil goes to the drain. This sets a constant oil flow through the corrector.
When changing the position of the spool, the piston moves after it (following system).
Air from the engine intake manifold is supplied through the threaded hole of the cover 21 into the cavity of the membrane.
When the air pressure drops below 0.04 MPa (0.4 kgf / cm2), the force of the corrector spring 7 acting on the spool becomes greater than the force created by the charge air pressure on the membrane and transmitted through the rod membranes and the corrector lever are also on the spool.
The spool moves to the right until the balance of forces acting on it.
Following the spool, the piston with pin 29 and tip 31 also moves to the right, moving the regulator lever 8 resting against it to the right (Figure 4).
After the regulator lever, under the action of the centrifugal forces of the weights, the levers 9,2 and 7 with the pump rails move in the direction of reducing the fuel supply.
Corrector adjustment
The corrector has two external adjustments - screws 11 and 15 (Figure 7).
Screw 11 changes the pretension of the corrector spring 7, while changing the beginning of the corrector operation.
If it is necessary to increase the value of the charge air pressure at which the corrector starts to work, then the screw 11 is turned in, increasing the preload of the spring 7.
Screw 15 regulates the nominal cyclic fuel supply. Turning out the screw 15 increases the fuel supply.
If it becomes necessary to remove the corrector, then it is first necessary to measure the protrusion of the tip of the stud 31 relative to the rear end of the injection pump housing, and after installing the corrector in place, restore the value of this protrusion and lock the tip with nut 30.
Injection pump drive is shown in Figure 8.
It consists of a drive shaft for injection pump 6 with packages of front 7 and rear 8 compensating plates, driven half-coupling 2, driven half-coupling flange 3, centering flange 4, drive half-coupling 9 and centering bushings 5.
Each package of compensating formationsying consists of 5 plates with a thickness of 0.5 mm each.
All bolts in the injection pump drive must be of strength class R100 and tightened with a torque of 65 ... 75 Nm (6.5 ... 7.5 kgf m).
The tightening of all bolts must be checked with a torque wrench. Before installing the bolts, check the presence of the centering sleeves.
Deformation (bending) of the front and rear compensating plates is not allowed.
The coupling bolt 10 of the drive coupling must be tightened last.
The fine fuel filter is shown in Figure 9. It is designed for the final purification of fuel from small particles before entering the injection pump.
The filter is installed at the highest point of the fuel supply system to collect and remove air into the tank along with part of the fuel through the valve (Figure 10) installed at the bypass from the filter
When replacing filter elements, it is necessary to strictly follow the rules for servicing the fuel supply system.
Do not let dirt enter the system and use filter elements only of the following models 740.1117040-01, 740.1117040-02, 740.1117040-04.
The valve is shown in Figure 10. When the pressure in cavity "A" of the fuel supply reaches 25...45 kPa (0.25...0.45 kgf/cm2), the ball 4 and the flow of fuel from cavity "A" to cavity "B" through valve jet 5.
At a pressure of 200...240 kPa (2...2.4 kgf/cm2), the valve is fully opened and fuel is bypassed into the fuel tank through cavity "B".
The piston-type fuel priming pump 13 (Figure 3) is designed to supply fuel from the tank through the coarse and fine filters and the fuel priming pump to the inlet cavity of the injection pump.
The pump is installed on the rear cover of the regulator, it is driven by an eccentric 19 located at the rear end of the injection pump camshaft.
Piston, piston spring, rod bushing 47 and pusher rod 48, inlet and discharge valves with springs are placed in the pump housing.
The eccentric 19 through the roller 49, the pusher 15 and the rod 48 reciprocates the piston of the fuel priming pump.
The pump operation diagram is shown in Figure 11.
When pusher 9 is lowered, piston 1 moves downwards under the action of spring 4. A vacuum is created in cavity "A" and inlet valve 2, compressing spring 3, passes fuel into cavity "A".
At the same time, the fuel in the discharge cavity "B" is forced out into the line "D", while the valve 5 closes under the action of the spring 6, eliminating the flow of fuel from the cavity "B" into the cavity "A".
When the piston 1 moves upwards, the fuel filling the cavity "A" through the discharge valve 5 enters the cavity "B" under the piston, while the inlet valve closes.
When the pressure in the discharge line increases, the piston does not make a full stroke after the pusher, but remains in a position that is determined by the balance of the fuel pressure force on one side and the spring force on the other.
Piston-type fuel priming pump 10 (Figure 11) is used to fill the fuel system with fuel before starting the engine and remove air from it.
The pump consists of a housing, piston, cylinder, inlet and discharge valves.
The fuel system should be pumped using the pump piston, having previously unlocked it by turning it counterclockwise.
When the piston 11 moves upwards, a vacuum is created in the space below it.
The inlet valve 12, compressing the spring 14, opens, and the fuel enters the cavity "D" of the pump.
When the piston moves down, the inlet valve closes and the discharge valve 13 opens, fuel under pressure enters the discharge line, ensuring the removal of air from the engine fuel system through the FTOT valve and the injection pump bypass valve.
After bleeding the system, it is necessary to lower the piston and fix it by turning it clockwise. In this case, the piston will press against the end of the cylinder through the rubber gasket, sealing the suction cavity of the fuel priming pump.
It is not allowed to start the engine with an unsecured piston due to the possibility of air leakage through the piston seal.
Fuel lines are subdivided into low pressure fuel lines - 0.4 ... 2 MPa (4 ... 20 kgf / cm2) and high pressure over 20 MPa (200 kgf/cm2).
Low pressure fuel lines are made of 10 mm steel pipe with brazed ends.
High-pressure fuel lines of equal length (1=595 mm) are made of steel tubes with an inner diameter of 2+0.05 mm by upsetting at the ends of the connecting cones with compression washers and union nuts for connection with the fittings of the injection pump and injectors.
The fuel lines are stapled to the intake manifolds to prevent damage from vibration