KR20110018062A - An electronic fuel injection control device for diesel engine - Google Patents

Abstract

PURPOSE: An electronic fuel injection controller for a diesel engine is provided to improve durability by periodically changing a fuel injection valve and to improve combustion performance by controlling injection pressure and time. CONSTITUTION: An electronic fuel injection controller for a diesel engine is composed as follows. Injection pressure control valves(8) are installed in an air inlet(41) formed on the top of a fuel injection valve(4). The injection pressure control valves are opened and closed by corresponding with an air pressure control signal outputted from an engine control unit(5). The injection pressure control valves control air pressure supplied to the fuel injection valve. An injection starting control valve(3) is installed between fuel supply holes(32) formed in a fuel injection pump(2) and a nozzle body(40).

Description

Electronic fuel injection control device for diesel engines {An electronic fuel injection control device for diesel engine}

The present invention relates to an electronic fuel injection control device for a diesel engine that can adjust the injection timing and injection pressure by using an electronically driven valve, more specifically, by opening the solenoid valve connected to the engine control unit according to the load conditions Close the injection timing, and the injection pressure control valve is also connected to the engine control unit to adjust the injection pressure.In low load, increase the injection pressure and advance the injection time to improve the combustion efficiency. The invention is invented to satisfy the engine's allowable strength condition by reducing the maximum cylinder pressure.

In other words, the injection start control valve and injection pressure control valve, which are very simple electronic valves, are installed in the existing mechanical fuel injection system to adjust the injection timing and injection pressure of the fuel through them, thereby greatly improving the combustion performance in the medium and low load areas. Invented to increase the injection pressure under low load conditions by controlling the common rail electronic control engine and to control the injection timing to prevent high fuel economy and excessive exhaust gas caused by low efficiency. The present invention relates to an electronic fuel injection control device for a diesel engine.

The mechanical fuel injection device of a diesel engine is generally fixed at the fuel injection timing by a cam shape and a fuel injection pump, and the injection timing cannot be changed depending on the load and the speed.

In addition, at low loads, since the fuel injection pressure is low, performance and efficiency are reduced, and a lot of exhaust gases such as smoke are generated.

In other words, in the low load condition of a general mechanical diesel engine, the injection pressure of the fuel generated by the fuel pump is lower than the high load condition.

This is due to the characteristics of the mechanical fuel pump, the low fuel injection pressure worsens the atomization of the fuel, reducing the combustion efficiency, resulting in high fuel economy, excessive exhaust gas, etc. do.

In order to improve the low load combustion characteristics, the present invention uses an electronically driven injection start control valve and an injection pressure control valve to increase the injection pressure at low load conditions and to accelerate the injection timing.

That is, in the mechanical diesel engine, fuel injection and injection are performed by a fuel injection pump driven by a fuel injection cam, so the fuel injection timing is fixed by the shape of the cam and the fuel injection pump. In general, diesel engines are designed to have maximum efficiency at 100% load conditions, so under low load operating conditions, poor atomization may occur as the injection pressure of the fuel drops. The sprayed state is to reduce the combustion efficiency to increase the exhaust gas and fuel economy, such as smoke and adversely affect the durability of the engine.

In order to solve such a problem, a conventionally developed common rail electronic control system is provided.

However, this system has the disadvantage of being very complicated in structure, difficult to manufacture, and expensive to modify the existing mechanical engine.

The present invention has been made in order to solve such a conventional problem, and the injection timing of the fuel through the injection start control valve and the injection pressure control valve that is electronically driven by mounting a very simple electronic valve in the existing mechanical fuel injection system and By adjusting the injection pressure, the combustion performance is greatly improved in the medium and low load range, and the effect is similar to that of the common rail electronic control engine.The combustion efficiency at the low load is improved by adjusting the injection pressure and injection timing. Exhaust gases such as fuel consumption and smoke can be reduced. Especially in the case of a large two-stroke diesel engine composed of one fuel injection pump and multiple fuel injection valves per cylinder, the injection is concentrated by blocking the fuel injection of one of the fuel injection valves at low and low loads. By increasing the injection pressure, the combustion efficiency can be further improved, and the fuel injection valve that blocks injection can be changed periodically to improve durability, and the start time of injection of several fuel injection valves can be changed slightly to change the engine combustion chamber. It is an object of the present invention to provide an electronic fuel injection control apparatus for a diesel engine that can alleviate the rapid pressure and temperature increase in the engine to significantly increase the durability of the engine and reduce the nitrogen oxide exhaust gas.

An apparatus for achieving the above object comprises: an engine control unit configured to receive an engine load, an engine speed, and a crank angle signal to perform an overall control function according to driving of a diesel engine; A governor for controlling the injection amount of the fuel injection pump according to the rotational speed of the engine and the load in response to the load control signal output from the engine control unit while being connected to the injection amount control mechanism of the fuel injection pump main body; A fuel injection pump driven by a fuel injection cam and compressing the fuel at an injection amount corresponding to the output of the governor to supply the fuel injection valve to the fuel injection valve; In the fuel injection device of a diesel engine having a fuel injection valve for injecting fuel from the fuel injection pump into the engine at a pressure corresponding to the air pressure, the engine control in the air inlet hole formed on the upper surface of the fuel injection valve An injection pressure control valve is installed to open and close in response to the air pressure control signal output from the unit, and to control the air pressure supplied to the fuel injection valve, and between the fuel injection pump and the fuel supply hole formed in the nozzle body of the fuel injection valves. It is operated in response to the injection timing control signal output from the engine control unit, characterized in that the injection start control valves for controlling the injection timing of the fuel to be injected into the engine from each fuel injection pump is installed.

At this time, the injection start control valve is a solenoid operated in response to the injection timing control signal of the engine control unit in the interior of the fuel supply hole and the fuel return hole connected to each other, the valve operating portion and the solenoid driven by the solenoid And a return spring is provided for connecting the fuel supply hole and the fuel return hole to each other when not in operation.

As described above, according to the present invention, a very simple electronic valve, that is, an electronically driven injection start control valve and an injection pressure control valve, is installed in the existing mechanical fuel injection system, and thus the injection timing and injection pressure of the fuel are adjusted. By adjusting it, the combustion performance can be greatly improved in the medium and low load area, and the effect can be similar to that of the common rail electronic control engine. Firstly, the exhaust gas such as fuel consumption and smoke can be reduced, and second, especially one cylinder In the case of a large two-stroke diesel engine composed of two fuel injection pumps and several fuel injection valves, the injection pressure is increased by blocking the fuel injection of one of the multiple fuel injection valves at a low speed and low load to concentrate the injection. It is possible to further improve the combustion efficiency, and the fuel injection valve that blocks the third injection The durability of the engine can be improved by improving the durability of the engine by reducing the sudden pressure and temperature increase in the engine combustion chamber by slightly changing the timing of injection of several fuel injection valves. It is a very useful invention that can be obtained.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows a schematic block diagram of the apparatus of the present invention, Figure 2 shows an operating state diagram of the fuel injection valve of the diesel engine to which the present invention is applied. (A)-(c) of FIG. 3 is a graph showing the increase in the fuel injection valve fuel injection starting pressure and its effect under low load conditions, and FIG. 4 (a) (b) is the plunger length of the fuel injection pump. 5 shows a graph of the variable injection timing and the maximum combustion pressure versus the engine load when the injection start time is advanced according to the increase. FIG. 5 shows the fuel injection pressure versus the crank angle according to the fuel injection timing and the fuel injection nozzle opening pressure. 6 shows a conversion graph, and FIG. 6 shows a block diagram when the present invention is applied to a large stroke diesel engine.

According to the present invention, the apparatus includes: an engine control unit 5 which receives an engine load, an engine speed, and a crank angle signal to perform an overall control function according to driving of a diesel engine; The injection amount of the fuel injection pump 2 according to the rotational speed and the load of the engine in response to the load control signal output from the engine control unit 5 while being connected to the injection amount adjusting mechanism 23 of the main body of the fuel injection pump 2. A governor 6 for controlling the; A fuel injection pump (2) driven by the fuel injection cam (1) and compressing the fuel at an injection amount corresponding to the output of the governor (6) and supplying the fuel to the fuel injection valve (4); Several fuel injection valves having a fuel injection amount adjustment port 42, a spring 43, and a nozzle body 40 and for injecting fuel from the fuel injection pump 2 into the engine at a pressure corresponding to the air pressure. A fuel injection device for a diesel engine having (4),

Injection to open and close the air inlet hole 41 formed on the upper surfaces of the fuel injection valves 4 in response to the air pressure control signal output from the engine control unit 5 and to adjust the air pressure supplied to the fuel injection valve 4. The pressure control valves 8 are additionally installed,

Between the fuel injection pump 2 and the fuel supply hole 44 formed in the nozzle body 40 of the fuel injection valves 4 is operated in response to the injection timing control signal output from the engine control unit 5, respectively. It is characterized in that the injection start control valves (3) for controlling the injection timing of the fuel to be injected into the engine from the fuel injection pump (2) is additionally installed.

At this time, the injection start control valve 3 is operated in response to the injection timing control signal of the engine control unit 5 in the interior of the body 30, the fuel supply hole 32 and the fuel return hole 31 is provided. Return that allows the fuel supply hole 32 and the fuel return hole 31 to be connected to each other when the solenoid 33, the valve actuating portion 34 driven by the solenoid 33, and the solenoid 33 are not operated. It is characterized by having a configuration in which the spring 35 is installed.

Referring to the effects of the electronic fuel injection control device for a diesel engine of the present invention configured as described above are as follows.

First, the present invention is a fuel injection device of a known diesel engine, the injection pressure control valve 8 which is controlled by the engine control unit 5 in the air inlet hole 41 formed on the upper surface of the fuel injection valve (4) And an injection start control valve 3 controlled by the engine control unit 5 between the fuel injection pump 2 and the fuel supply hole 44 formed in the nozzle body 40 of the fuel injection valves 4. The main components of this installation are additional installations.

At this time, the injection pressure control valve 8 is opened and closed in response to the air pressure control signal output from the engine control unit 5 and controls the air pressure supplied to the fuel injection valve 4, and the injection start The control valve 3 has a solenoid 33, a valve actuating portion 34, and a return spring 35, and operates in response to the injection timing control signal output from the engine control unit 5, and each fuel injection pump. In (2), the function of controlling the injection timing of the fuel injected into the engine is performed.

In addition, the injection start control valve 3 is a solenoid operated in response to the injection timing control signal of the engine control unit 5 inside the body 30 provided with the fuel supply hole 32 and the fuel return hole 31. (33) is installed, as well as the fuel supply hole when the valve operating portion 34 and the solenoid 33 that is driven by the solenoid 33 to control the opening and closing amount of the fuel return hole 31 is not operated The return spring 35 which has 32 and the fuel return hole 31 connected to each other is provided.

The mechanical fuel injection pump 2 driven by the fuel injection cam 1 in the diesel engine to which the apparatus according to the present invention is applied has a fuel injection valve 4 through the injection start control valve 3 by pressurizing the fuel. The fuel is delivered at high pressure, where the injection amount of the fuel is determined by the amount of fuel compressed in the fuel injection pump 2, which is controlled by the governor 6 connected to the engine control unit 5.

In addition, since the injection pressure control valve 8 is connected to the air inlet hole 41 formed on the upper surface of the fuel injection valve 4, it is supplied into the fuel injection valve 4 through the injection pressure control valve 8. The compression force of the spring 43 is adjusted in accordance with the air pressure to control the fuel injection pressure.

In this way, when the injection start pressure of the fuel injection valve 4 is increased at low load, the time for reaching the increased injection pressure is increased, resulting in a delay in the injection timing, and as a result, the combustion chamber of the engine. The maximum pressure (Pmax) in the (not shown) is reduced, and the fuel efficiency and exhaust gas increase because the combustion efficiency is lowered.

Therefore, although the injection pressure of the fuel is increased at low load, the injection timing is delayed and the effect of increasing the injection pressure is halved.

In addition, by controlling the air pressure in accordance with the load and speed of the engine to control the fuel injection start pressure of the fuel injection valve 4, where the injection pressure control valve 8 may be replaced by a solenoid valve.

That is, the fuel injection start pressure may be controlled by compressing the spring 43 by a solenoid driven as an electrical signal instead of the air pressure.

As described above, the present invention adjusts the fuel injection timing to return the injection timing delayed due to the increase in the fuel injection starting pressure to the existing state. The injection timing is increased by increasing the plunger 22 length in the general mechanical fuel injection pump 2. This can bring about an effect.

When such a configuration is applied, as shown in the graph of the fuel injection valve fuel injection start pressure increase and its effect under the low load condition shown in FIGS. 3A to 3C, the fuel injection pump 2 Since the compression of the fuel begins at the time when the plunger 22 blocks the fuel supply hole 21, the length of the plunger 22 is increased so that the time at which the fuel supply hole 21 is blocked is advanced, and the fuel is compressed. And the start of injection is also advanced.

In addition, as the fuel injection timing is advanced as shown in FIG. 4A, the combustion efficiency increases and the maximum explosion pressure in the combustion chamber also increases.

As the injection pressure increases, the injection inertia of the fuel increases when the fuel is injected from the fuel injection nozzle, so that the mixture is better mixed with the air in the combustion chamber, and when the fuel injection timing is advanced, the fuel and air are mixed and explode. Since the time to reach the state is sufficiently increased, by increasing the injection pressure of the fuel in the low load region and advancing the injection timing, the fuel can be mixed with the air more smoothly than before, greatly improving the combustion efficiency, lowering fuel economy and exhaust gas Can be reduced.

In the above, when the plunger 22 length of the fuel injection pump 2 is extended, the effect of accelerating the fuel injection start time is brought.

Therefore, when the fuel injection timing is accelerated in the low load region, the fuel injection timing, which has been delayed due to the fuel injection starting pressure, is accelerated again, resulting in a good mixing of the injected fuel and air, increasing the combustion efficiency and increasing the maximum pressure in the combustion chamber (Pmax). Also increases.

In addition, the fuel injection timing can be further improved by lowering the fuel injection timing in the low load region, but as the engine load rises, the pressure limit in the combustion chamber is reached. Do not exceed.

As described above, when the fuel injection time is advanced, the maximum combustion chamber pressure also increases as the combustion efficiency increases, but the maximum pressure of the engine combustion chamber has a limit value considering the strength of components such as a cylinder head. By using 3), in the low load or the medium load region, the fuel injection timing is further advanced to increase the combustion efficiency, and in the high load region, the fuel injection timing is delayed again so that the maximum pressure of the combustion chamber does not exceed the limit. (B) of)

At this time, the fuel injection timing is determined by the injection start control valve 3 driven by the solenoid 33, the injection start control valve 3 by the engine control unit 5 received the engine load and the speed signal, etc. Controlled.

In the system consisting of the conventional mechanical fuel injection pump (2) and the fuel injection valve (4), since the compression and injection of the fuel starts from the time when the plunger 22 blocks the fuel supply hole 21, fuel by engine load, speed Injection timing control is impossible, but in the case of applying the present invention, since the injection start control valve 3 is always opened by the spring 43, the compression and injection timing of the fuel is controlled from the solenoid 33 from the engine control unit 5. Since the injection current is applied to the injection start control valve 3 to be closed, the injection timing can be freely adjusted according to the engine load and speed, and FIG. 5 is according to the fuel injection timing and the fuel injection nozzle opening pressure adjustment. A graph of fuel injection pressure versus crank angle is shown.

On the other hand, while the common rail electronic control engine controls all the various variables such as fuel injection pressure, injection start time and end time (fuel injection amount), in the diesel engine to which the present invention is applied, fuel injection is performed based on a mechanical engine. Only the start time and injection pressure are controlled, and the end time (fuel injection amount) is controlled by the governor 6 in the same way as the existing mechanical system. The advantage is that the logic is simple to configure.

Such a device of the present invention may be applied to both 2 and 4 stroke diesel engines, and particularly when applied to a large two stroke engine as shown in FIG. 6, it has an additional advantage in addition to the aforementioned effects.

In this case, two or more fuel injection valves 4 may be installed in one fuel injection pump 2 per cylinder.

Therefore, when the device of the present invention is applied to a large two-stork engine, not only can control the injection pressure and the injection timing of the fuel, but also selectively control the fuel injection blocking and the injection sequence according to the attachment position and the number of valves. Since it is possible to increase the injection pressure of the fuel in the low load region, and to increase the durability of the fuel injection valve (4) as well as to obtain an additional effect such as exhaust gas reduction.

When the present invention is applied to the diesel engine as described above, the injection timing and pressure of the fuel are controlled using the injection start control valve 3 and the injection pressure control valve 8 to greatly increase the combustion efficiency in the low and medium load regions. In this case, the injection start control valve (3) can be manufactured in a small size, operate at a low pressure, there is no fuel leakage, quick response, fuel injection valve (4) and fuel injection pump (2) and It is easy to install due to various installation positions such as fuel piping.

That is, the device of the present invention can exhibit an effect similar to that of the common rail electronic control engine at low cost by attaching the injection start control valve 3 and the injection pressure control valve 8, which are simple electronic control valves, to an existing mechanical diesel engine. It has the advantage and can be mounted on 2 and 4 Stoke diesel engines, and can be mounted regardless of engine size, especially the large 2 consisting of two or more fuel injection valves in one fuel pump per cylinder. When installed on a stroke diesel engine, there are additional advantages:

First, it is possible to improve combustion efficiency at low load through the control of fuel injection timing and injection pressure. Second, injection is concentrated by blocking fuel injection of one of several fuel injection valves at low speed and low load. By increasing the injection pressure, the combustion efficiency can be further improved.The durability can be improved by periodically changing the fuel injection valve that blocks the third injection.The fourth injection timing of several fuel injection valves is slightly different. Therefore, by reducing the sudden pressure and temperature increase in the engine combustion chamber increases the engine durability and has the effect of reducing the nitrogen oxide exhaust gas.

It should be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

1 is a schematic block diagram of a device of the present invention;

Figure 2 is a state diagram of the operation of the fuel injection valve of the diesel engine to which the present invention is applied.

(A)-(c) of FIG. 3 are graphs illustrating an increase in fuel injection start pressure and its effect at low load conditions;

Figure 4 (a) (b) is a graph of the variable injection timing and the maximum combustion pressure compared to the engine load when the injection start time is accelerated by increasing the plunger length of the fuel injection pump.

5 is a graph of conversion of fuel injection pressure to crank angle according to fuel injection timing and fuel injection nozzle opening pressure adjustment;

6 is a block diagram when the present invention is applied to a large stroke diesel engine.

Explanation of symbols on the main parts of the drawings

1: fuel injection cam 2: fuel injection pump

21: fuel supply hole 22: plunger

23: injection amount adjustment mechanism 3: injection start control valve

30: body 31: fuel return ball

32: fuel supply hole 33: solenoid

34 valve operation part 35 return spring

4 fuel injection valve 40 main body

41: air inlet hole 42: fuel injection amount control

43: spring 44: fuel supply hole

5: engine control unit 6: governor

8: injection pressure control valve

Claims (2)

An engine control unit which receives an engine load, an engine speed, and a crank angle signal to perform an overall control function according to driving of a diesel engine; A governor for controlling the injection amount of the fuel injection pump according to the rotational speed of the engine and the load in response to the load control signal output from the engine control unit while being connected to the injection amount control mechanism of the fuel injection pump main body; A fuel injection pump driven by a fuel injection cam and compressing the fuel at an injection amount corresponding to the output of the governor to supply the fuel injection valve to the fuel injection valve; In the fuel injection device of a diesel engine having a fuel injection valve for injecting the fuel supplied from the fuel injection pump into the engine at a pressure corresponding to the air pressure, Injecting pressure control valves for opening and closing in response to the air pressure control signal output from the engine control unit to control the air pressure supplied to the fuel injection valve in the air inlet hole formed on the upper surface of the fuel injection valve, Between the fuel injection pump and the fuel supply hole formed in the nozzle body of the fuel injection valve is operated in response to the injection timing control signal output from the engine control unit, the injection to control the injection timing of the fuel injected from the fuel injection pump to the engine An electronic fuel injection control device for a diesel engine, characterized by an additional start control valve. The method according to claim 1, The injection start control valve may include a solenoid operated in response to an injection timing control signal of an engine control unit in a body provided with a fuel supply hole and a fuel return hole connected to each other, a valve operation unit and a solenoid driven by the solenoid. Electronic fuel injection control device for a diesel engine, characterized in that the configuration has a return spring is installed so that the fuel supply hole and the fuel return hole is connected to each other when not operated.

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