RU2278295C1 - Diesel engine fuel-feed accumulator system - Google Patents

Abstract

FIELD: mechanical engineering; diesel engines.

SUBSTANCE: proposed fuel-feed accumulator system consists of fuel tank, fuel heater with thermostat, fine fuel filter, low-pressure fuel pump, cutoff electric valve, high pressure fuel pump, pressure transmitter, high-pressure accumulator, pressure regulating electric valve, fuel cooler, electrohydraulic nozzles and low-temperature air radiator. Fuel-feed system is furnished additionally with low-pressure accumulator placed in nozzle leak-off fuel system and divided into two parts with restrictor in between. Leak-off fuel pipes from nozzles are connected to first part of accumulator, and second part of accumulator is connected through non-return valve to fuel tank through fuel cooler. Non-return valve is adjusted to opening pressure not lower than 4-5 MPa.

EFFECT: provision of quick action of nozzles, reduced consumption of fuel for control, improved serviceability of fuel-feed system.

1 dwg

Description

The invention relates to engine building, in particular to systems for supplying fuel to a diesel engine.

Of the known closest to the claimed technical essence and the achieved positive effect is a diesel diesel fuel supply system containing a fuel tank, a fuel heater, a low pressure fuel pump, an isolation valve, a high pressure fuel pump, a pressure sensor, a high pressure accumulator, a pressure control solenoid , fuel cooler, electro-hydraulic nozzles and low temperature air radiator.

A disadvantage of the known fuel supply system is the probability of the appearance of vapor-gas bubbles in the hydraulic control chamber during certain injection modes and, as a consequence, the slowdown at the most critical moment of the injection process during cut-off, as well as the difficulty of further reducing fuel consumption for control (Grekhov L. B. Fuel equipment of diesel engines with electronic control.Training and practical manual.M: Legion - Avtodata, 2003, p.65 ... 67 - prototype).

The invention solves the problem of increasing the speed of the nozzle, reducing fuel consumption for control and increasing the efficiency of the fuel supply system.

The technical problem is solved due to the fact that the diesel engine fuel supply system containing a fuel tank, a fuel heater with a thermostat, a fuel fine filter, a low pressure fuel pump, an isolation valve, a high pressure fuel pump, a pressure sensor, a high pressure accumulator, a control solenoid pressure, fuel cooler, electro-hydraulic nozzles, low-temperature air radiator, according to the invention, supplemented by a low-pressure battery included in the system the topic of draining fuel from nozzles and divided into two parts, between which a throttle is located, and drain pipes from nozzles are connected to the first part of the battery, and the second part of the battery is connected to the fuel tank through a non-return valve and the non-return valve is not adjusted to the opening pressure below 4 ... 5 MPa. The non-return valve design provides for the ability to control the upper limit of the fuel pressure in the battery.

The technical essence of the claimed invention is illustrated in the drawing, which shows a diagram of the inventive diesel fuel supply system.

The diesel fuel supply system comprises a fuel tank 1, a fuel heater with a thermostat 2, a fuel fine filter 3, a low pressure fuel pump 4, an electric shut-off valve 5, a high pressure fuel pump 6, a pressure sensor 7, a high pressure accumulator 8, a pressure control solenoid 9, a fuel cooler 10, electro-hydraulic nozzles 11, a low-temperature air radiator 12, an inductor 13 separating the first cavity of the low-pressure accumulator 14 from the second cavity of the accumulator 15, non-return valve 16.

Studies of diesel fuel supply systems found that during the end of injection with a decrease in pressure during cut-off, gas bubbles are formed in the high pressure line and nozzle in the fuel, consisting of air and fuel vapor. The air dissolved in the fuel is released in the form of bubbles with a decrease in pressure in fractions of a millisecond, and with an increase in pressure it dissolves rather slowly. The content of fuel vapor in the bubbles depends on the temperature of the fuel, and the higher it is, the more fuel vapor in them.

It was also established that with increasing fuel pressure to about 4 MPa, gas bubbles disappear or become unusually small in size and do not have a significant negative effect on the injection process.

In the accumulator fuel supply system adopted as a prototype, in the absence of a low-pressure accumulator during injection, the fuel pressure in the nozzle hydraulic control chamber during diesel operation in a wide range of the engine crankshaft speed, load changes, transient operating modes, and oscillatory processes in the fuel supply system can decrease to the point where gas bubbles can form in the fuel.

At the very least, there are no guarantees that during the operation of the diesel engine when injecting fuel in the control chamber, nozzles of such bubbles will not form, if one takes into account that when the hydraulic control valve is open in the drainage system, the pressure is not much higher than 0.1 MPa, and due to the occurrence of oscillatory processes, it can decrease significantly below 0.1 MPa. The formation of gas bubbles in the nozzle hydraulic control chamber is especially detrimental to the process of the end of injection at the time of cut-off. The cut-off becomes less sharp, as a result of which, in the final phase of the injection process, the atomization of the fuel deteriorates, and this is associated with an increased likelihood of coking of the nozzle openings of the atomizer nozzle, the formation of large droplets of atomized fuel and diesel smoke.

The proposed battery fuel supply system, due to the presence of a low-pressure battery, eliminates any possibility of a decrease in fuel pressure in the nozzle hydraulic control chamber below 4 ... 5 MPa, which ensures that under all possible diesel operating conditions there is no formation of gas bubbles in the fuel.

The battery diesel fuel supply system operates as follows.

When an electric current pulse is fed into the electromagnet or the nozzle piezo actuator, the hydraulic control valve is activated and the fuel pressure in the hydraulic control chamber sharply decreases, due to which the multiplier with the needle valve of the atomizer nozzle moves to the open side and fuel injection into the diesel combustion chamber begins. After closing the hydraulic control valve in the hydraulic control chamber, the fuel pressure rises and the multiplier, together with the needle valve of the sprayer, moves towards the nozzle closing direction. Under no circumstances does the pressure decrease in the process of fuel injection in the hydraulic control chamber occur below 4 ... 5 MPa due to the fact that the pressure in the range 4 ... 5 MPa is maintained in the first cavity of the low-pressure accumulator 14, and therefore, in the process no gas bubbles are injected.

Any valve has a certain inertness. Therefore, to reduce pressure fluctuations in the first cavity of the low-pressure accumulator 14, it is separated from the second cavity of the accumulator 15 by a throttle 13, the throughput of which is determined by the fuel consumption for control at the nominal operating mode of the diesel engine.

The opening pressure of the non-return valve 16 is set optimal for a diesel engine, but not lower than 4 ... 5 MPa. At the same time, in the proposed fuel supply system, due to the increased pressure of the fuel in the low-pressure accumulator at a constant fuel pressure in the high-pressure accumulator 8, the fuel consumption for control is somewhat reduced, and the absence of gas bubbles increases the speed of the nozzle compared to the prototype.

The volume of the cavities of the low-pressure accumulator is selected from the condition of ensuring permissible fluctuations in the pressure of the fuel, especially in the first cavity 14 of the accumulator, the volume of the second cavity 15 is not significant and can be selected from structural considerations.

The proposed addition to the diesel battery system does not require large additional costs and is easily feasible.

Claims (1)

Accumulator diesel fuel supply system, consisting of a fuel tank, a fuel heater with a thermostat, a fuel fine filter, a low pressure fuel pump, an electric shut-off valve, a high-pressure fuel pump, a pressure sensor, a high-pressure accumulator, a pressure control electro-valve, a fuel cooler, and electro-hydraulic nozzles , low-temperature air radiator, characterized in that the fuel supply system is supplemented by a low-pressure accumulator included in the system fuel drain from nozzles and divided into two parts, between which a throttle is placed, drain pipes from nozzles are connected to the first part of the accumulator, and the second part of the accumulator is connected through the non-return valve through the fuel cooler to the fuel tank, and the non-return valve is adjusted to the opening pressure not lower than 4 ÷ 5 MPa.