RU2342555C1 - Fuel supply system to diesel - Google Patents

Abstract

FIELD: motors and pumps.

SUBSTANCE: invention relates to engine engineering and, particularly to fuel supply system of diesel engine. According to the invention the fuel supply system in diesel engines contains high-pressure fuel pump, pressure valve, makeup main line, additional channel and non-return valve. The pump is linked with makeup main line and coupled with injector through the pressure valve and high-pressure pipeline. The non-return valve is located in additional channel, which is connected with high-pressure pipeline by one of its ends and with makeup main line by the another end. In addition auxiliary high-pressure fuel pump with pressure valve and high-pressure battery are available in the system. They are coupled with non-return valve by means of makeup main line. The relief valve linked with low-pressure pipeline is mounted on high-pressure battery.

EFFECT: improvement of power and economic characteristics and reduction of exhaust smoke emissions and toxicity.

1 dwg

Description

The invention relates to the field of engine engineering, in particular to a fuel-supplying equipment of diesel engines.

A known system for supplying fuel to a diesel engine comprising a high pressure fuel pump, a discharge valve, a feed line, an additional channel and a non-return valve, the pump being connected through a pressure valve and a high pressure pipe to the nozzle, and a non-return valve is placed in the additional channel, which is connected at one end with a high pressure pipeline, and another with a feed line, while the standard fuel intake is made of a floating type and the system is additionally equipped with a fuel supply a suction pump, a fuel intake of heavy impurities that are located in the lower part of the fuel tank and are connected by a feed line to a non-return valve (RF patent No. 2184265, IPC F02M 55/00, 2002).

However, this system of fuel supply to diesel does not improve the flow of the working process due to the injection of heavy impurities from the fuel tank into the diesel cylinder together with diesel fuel. In this case, the combustion process inevitably worsens with an increase in the content of toxic components and soot particles in the exhaust gases. As a result, the power and economic performance of the diesel engine deteriorates, the service life of the precision pairs (nozzle-sprayer) of the nozzle and the non-return valve with the seat decreases, and the nozzle filter may become clogged, which will lead to the failure of the nozzle and, as a result, to uneven operation of the diesel engine. In addition, this system of fuel supply to diesel does not provide an increase in the residual pressure in the high pressure pipeline to the optimum value, which leads to a deterioration in engine power and economic performance, to increased smoke and toxicity of exhaust gases.

All of the above will lead to a decrease in the reliability and durability of the diesel engine.

The closest technical solution, selected as a prototype, is a fuel supply system for a diesel engine containing a high pressure pump, a discharge valve, a feed line, an additional channel and a non-return valve with an unloading belt, and the pump is connected to the feed line and connected through the discharge valve and pipeline high pressure with a nozzle, and a non-return valve is placed in an additional channel, which is connected at one end to the high pressure pipeline and the other end to the supply line, and the additional channel is constantly connected to the supply line and contains a throttle, while the throttle is made in the form of radial and axial holes in the body of a non-return valve (RF patent No. 2171908, IPC F02M 55/00, 2001).

However, the known system for supplying fuel to a diesel engine does not provide an increase in the residual pressure in the high pressure pipe to an optimum value. This leads to a decrease in injection pressures at low cyclic feeds and low crankshaft rotational speeds compared with the values that occur at maximum speed due to a drop in the average speed of the plunger during the active stroke with a decrease in speed.

It is known that with an increase in the residual pressure that is established in the discharge pipe between successive fuel injections, the injection pressure increases at the same volumetric rate of fuel supply by the plunger [1].

With a reduced pressure of fuel injection into the combustion chamber, the rate of fuel outflow from nozzle nozzle openings decreases, which leads to a deterioration in the fineness and uniformity of atomization, a slowdown of the combustion process of the working mixture, a decrease in the active stroke of the plunger and the size of the cyclic feed [1]. All of the above leads to a deterioration in the flow of the working cycle and, as a consequence, to a decrease in power and economic indicators of the engine, to a decrease in smoke and toxicity of exhaust gases.

The technical result is aimed at increasing the power and economic indicators of the engine, at reducing smoke and toxicity of exhaust gases.

The technical result is achieved by the fact that in the fuel supply system to a diesel engine containing a high pressure fuel pump, a discharge valve, a feed line, an additional channel and a non-return valve, the pump being connected to a feed line and connected through a pressure valve and a high pressure pipe to a nozzle, and a non-return valve is located in an additional channel, which is connected at one end to a high-pressure pipeline and the other to a feed line; a high-pressure fuel pump with a discharge valve and a high-pressure accumulator connected by a feed line to a non-return valve, and a pressure-reducing valve connected to the low-pressure pipeline is placed on the high-pressure accumulator.

Distinctive features of the prototype is that an auxiliary high-pressure fuel pump with a discharge valve and a high-pressure accumulator connected by a feed line to a non-return valve are additionally introduced into the system, and a pressure-reducing valve connected to the low-pressure pipe is placed on the high-pressure accumulator.

Signs that distinguish the claimed technical solution in other technical solutions in the study of this and related areas of technology have not been identified and, therefore, provide the claimed solution with the criteria of "significant differences" and "novelty."

The drawing shows a system for supplying fuel to a diesel engine.

The system comprises low pressure pipelines 1, 2 and 3, a high pressure fuel pump 4 with a discharge valve 5, a high pressure pipeline 6, a nozzle 7, a non-return valve 8 located in an additional channel 9, the additional channel 9 being connected to the high pressure pipe at one end 6, and the other with the feed line 10. The feed line 10 connects the auxiliary high pressure fuel pump 11 to the non-return valve 8 through the high pressure accumulator. The pump 11 is connected through a pipe 3 to a pipe 1. A pressure valve 12 is located in the pump 11, and a pressure reducing valve 14 is installed on the high-pressure accumulator 13, consisting of a ball 15 and a spring 16. The pressure reducing valve 14 is connected via a pipe 2 to a pipe 3. An auxiliary fuel the high pressure pump 11 is designed to supply high pressure fuel to the high pressure accumulator 13. The pressure relief valve 14 limits the fuel pressure in the high pressure accumulator 13. The pressure relief valve 14 is adjusted The pressure is 20% less than the pressure of the nozzle 7 needle in the saddle. For example, for a KamAZ-740.10 diesel, the pressure of the nozzle needle into the saddle is 10 MPa [2]. In this case, the pressure reducing valve 14 should be adjusted to a pressure of 8 MPa in order to compensate for possible surges in fuel pressure in the high pressure pipe 6.

The proposed fuel supply system operates as follows.

With the active stroke of the plunger of the high pressure fuel pump 4, the discharge valve 5 opens and the fuel enters the high pressure pipe 6 and the nozzle 7, from which it is injected into the diesel cylinder. During the injection process, the fuel pressure in the high-pressure pipe 6 and in the nozzle 7 increases until the supply is cut off, and then sharply decreases until the discharge valve 5 of the pump 4 fits into the saddle. Before the discharge valve 5 is seated in the seat, despite the openings in the nozzle 7 nozzle, the fuel injection pressure will increase, since the amount of fuel displaced by the plunger of the high pressure pump 4 is much larger than the amount that flows through the nozzle 7 openings into the diesel combustion chamber . The increase in pressure at pump 4 continues until the cutoff begins. In this case, the fuel from the high pressure pipe 6 will flow into the low pressure pipe 1 through the discharge valve 5.

After the cut-off, the discharge valve 5 of the pump 4 sits on the seat and disconnects the fuel line 6 from the above-plunger space. Further fuel supply to the combustion chamber of the diesel engine is carried out due to the energy accumulated during compression of the fuel by the pump plunger, and continues until the nozzle needle 7 is put on the saddle. The nozzle needle 7 sits in the saddle quickly due to a sharp decrease in fuel pressure acting on the needle cones. When fuel is injected into the diesel cylinder, the non-return valve 8 is closed, since the fuel pressure in the additional channel 9 and in the high pressure pipe 6 is higher than the fuel pressure of the feed line 10, into which the fuel comes from the high-pressure accumulator 13. Fuel to the high-pressure accumulator 13 it is constantly pumped by the auxiliary high-pressure pump 11. In the process of pumping fuel into the accumulator 13, the discharge valve 12 of the pump 11 is open, and when the plunger space is filled with fuel from the master whether 3 is closed.

When the fuel pressure in the high-pressure accumulator 13 is exceeded above 8 MPa for the KamAZ-740.10 diesel engine, the pressure reducing valve ball 15 opens, the spring 16 is compressed, and the fuel flows from line 2 to line 3.

After the discharge valve 5 and the nozzle needle 7 are seated on their seats, the pressure in the high pressure pipe 6 will be less than in the feed line 10. Therefore, the non-return valve 8 will open and the pressure in the high pressure pipe 6 will increase to the pressure to which the pressure reducing valve 14 is adjusted high pressure 13.

Thus, the excess fuel pressure in the high pressure pipeline 6 in the time intervals between fuel injection into the cylinder will also not exceed 8 MPa for the KamAZ-740.10 diesel engine. This pressure value eliminates the arbitrary injection of fuel into the cylinder, since a higher pressure is required to inject fuel into the cylinder. For example, for a KamAZ-740.10 diesel, the pressure of the needle lift of the nozzle 7 is 21 MPa.

It is known that with an increase in the residual pressure in the high pressure pipe 6, the fuel injection pressure increases, but the nozzle needle’s landing speed slows down and the possibility of additional injections appears. Excessive unloading of the high pressure pipeline leads to a disruption in the continuity of the fuel flow and, as a consequence, to an increase in the injection delay and a decrease in the steepness of the front of the pressure pulse [3].

The residual pressure in the system with the discharge valve 5 having a constant discharge stroke depends on the mode of operation of the diesel engine. So, with partial engine operation, the fuel line 6 is almost completely unloaded, which increases the throttling periods of the fuel and increases the sensitivity of the pump section to the resistance of the discharge path. However, even with a constant discharge stroke of the discharge valve 5, the stability of the fuel supply can be significantly improved by increasing the pressure at which the rise of the discharge valve 5 begins. In order to increase the opening pressure of the discharge valve 5, it is proposed to increase it in the high pressure pipe 6 to a pressure that is less than the pressure of the nozzle 7 nozzle in the nozzle seat of the nozzle is approximately 20%. The fuel in the high pressure pipe comes from the high-pressure accumulator 13 immediately after the nozzle 7 nozzles fit into its seat through the non-return valve 8. The opening pressure of the non-return valve is also 20% less than the pressure of the needle in the seat.

It is known that fuel is injected into the cylinder under varying pressure of the fuel in the cylinder, the most favorable conditions for spraying being the middle part of the injection process. The beginning and end of injection occur at lower pressures, which causes the appearance of unacceptably large drops and a decrease in the range of part of the cyclic feed.

Especially difficult is the provision of a sharp cut-off at the end of the fuel supply, due to the formation of wave phenomena in the high pressure fuel line. In this case, due to a sharp decrease in pressure in the supraplunger cavity, when the fuel passage opens into the shut-off window, the pressure valve spring 5 closes the valve, and the volume of the high-pressure fuel line is closed. The residual pressure in it, depending on the operating mode of the engine, can vary from 1 to 5 MPa [3].

In the claimed technical solution, the residual pressure in the high pressure pipeline will be not 1-5 MPa, but 8 MPa in all diesel operation modes.

In the subsequent process of injecting fuel into the diesel cylinder, a larger active stroke of the plunger of the high pressure fuel pump 6 will be used to inject fuel, while the injection pressure will increase. With an increase in the injection pressure, the flow rate of the fuel along the channels of the nozzle atomizer increases and the rate of flow of the fuel from the atomizer to the combustion chamber. In this regard, firstly, perturbations in the fuel stream are intensified, leading to the appearance of vortex movements inside the jet and on its periphery, and, secondly, due to the increased influence of aerodynamic forces on the surface of the jet at higher flow rates, the fragmentation effect of air charge in the combustion chamber into which fuel is injected. As a result of the combined influence of these factors, the decay of the fuel stream is significantly facilitated and smaller, more uniform droplets of fuel are obtained, that is, the fineness and uniformity of atomization due to an increase in the active stroke of the plunger are improved, the cyclic supply of fuel to the cylinder increases, and the unevenness of fuel supply along the cylinders, stable minimum feeds are ensured at low load, idle and fuel supply equipment optimization, while the necessary imye quality dynamic engine transient operation modes. In addition, increasing the injection pressure optimizes the workflow according to the criteria of economy, reduction of toxicity and smoke of exhaust gases. It was revealed that with fine atomization at high pressures through small nozzles, the self-ignition delay time is noticeably reduced. In this case, the process of formation of nitrogen oxides NO at a moderate maximum pressure in the cylinder and the stiffness of combustion are caused by small advancing angles of fuel injection and the dynamic factor of flow, and good fuel economy and low smoke emissions are caused by the fineness of atomization when injecting fuel at high pressures through small atomizing openings of the atomizer nozzles [3].

Thus, the use of the inventive system for supplying fuel to diesel improves the flow of the working process, which increases the power and economic performance of the engine and reduces the smoke and toxicity of exhaust gases.

Information sources

1. Sins L.V., Ivashchenko N.A., Markov V.A. Fuel equipment and diesel control systems. - M.: Legion-Avtodata. 2004 .-- 342 p.

2. Abelyan A.M. Improving the fuel supply system for diesel engines of military vehicles. Dis. ... cand. tech. sciences. - Ryazan, 1998 .-- 156 p.

3. Buryachko V.R., Guk A.V. Car engines. NPICC. - St. Petersburg. 2005 .-- 291 p.

Claims (1)

A fuel supply system to a diesel engine comprising a high pressure fuel pump, a discharge valve, a feed line, an additional channel and a non-return valve, the pump being connected to a feed line and connected through a pressure valve and a high pressure pipe to the nozzle, and the non-return valve is located in an additional channel, which is connected at one end to a high-pressure pipeline and the other to a feed line, characterized in that auxiliary fuel is additionally introduced into the system a high-pressure pump with a discharge valve and a high-pressure accumulator connected by a feed line to a non-return valve, and a pressure-reducing valve connected to the low-pressure pipeline is placed on the high-pressure accumulator.