KR20030083423A - Fuel injection system of diesel engine - Google Patents

Abstract

PURPOSE: A fuel injection system is provided to prevent waste of fuel, noises and soot formation by allowing for an electronic control of fuel supply. CONSTITUTION: A fuel injection system comprises a plunger driving at the maximum effective stroke; a branch pipe(64) branched off from a fuel supply pipe and connected to a fuel tank(10); an electronic control valve(66) communicated to the branch pipe, which opens/shuts in accordance with a control signal so as to guide the flow of the fuel to the fuel tank; a pedal sensing unit for sensing the operation of an accelerating pedal; and a controller(72) for receiving the engine state sensing signal including the signal applied from the pedal sensing unit, and applying a control signal to the electronic control valve.

Description

Fuel injection system of diesel engine

The present invention relates to a fuel supply system of a diesel engine that enables electronic control of a mechanical mechanism for supplying fuel to a diesel engine.

In general, as a fuel supply process of a diesel engine by a mechanical mechanism, as shown in FIG. 1, the fuel contained in the fuel tank 10 passes through the fuel filter 14 by the fuel supply pump 12. The combustion chamber 22 is passed through the fuel injection nozzle 20 through the opening of the delivery valve 18 and the fuel pipe 19 by being driven to the injection pump 16 and again driven by the fuel injection pump 16. In the atomization (atomization) state in the injection is supplied.

Here, the configuration of the above-described fuel injection pump 16 and the driving relationship according to these configurations will be described in more detail. As shown in FIG. 2, the camshaft 24 that cooperates with the crankshaft (omitted for simplicity of the drawing) is shown. At one side of the camshaft 24 opposite to the cam 26, the tappet assembly 30 which receives the elasticity of the return spring 28 and continuously contacts the cam 26 is rotated by the cam 26. The plunger 32 supported by the tappet assembly 30 is rotatable through the inner side of the sleeve 34 and the barrel 36 which are installed in succession in the longitudinal direction again. Linear reciprocating motion.

At this time, the fuel supply relationship according to the linear reciprocating motion of the plunger 32, as shown in Figure 3a to 3d, the fuel flowing into the suction / return port 38 formed on the side of the barrel 36 to the upper portion The delivery valve 28 is pressurized, and the delivery valve 28 is opened by pressurization higher than or equal to the set position by the lifting position of the plunger 32 such that the pressurized fuel is injected through the fuel pipe 19 through the fuel injection nozzle 20. To move to

On the other hand, FIG. 3A shows a case where the cam 26 is in a low position without changing the rotation angle displacement of the cam shaft 24. The end of the plunger 32 has a suction / return port formed in the barrel 36. FIG. Located at the lower portion of the 38, at this time, the fuel guided by the fuel supply pump 12 inside the barrel 36 is filled through the suction / return port 38 to be filled, and at the same time a delivery valve ( 18 is a state in which the passage leading to the fuel injection nozzle 20, that is, the fuel pipe 19 is blocked.

Then, when the rotation angle displacement change of the cam 26 is positioned by the continuous rotation of the camshaft 24, as shown in FIG. 3B, the plunger 32 is supported by the tappet assembly 30 and driven up and down to drive the plunger 32. The fuel introduced into the barrel 36 is pressurized from the time point when the upper end of the bar passes through the position of blocking the suction / return port 38 formed at the side of the barrel 36.

As shown in FIG. 3C, when the upper portion of the plunger 32 is further raised by the continuous rotation of the camshaft 24, the fuel in the barrel 36 exceeds the blocking force of the delivery valve 18. It is pressurized to open the delivery valve 18 and flow to the fuel injection nozzle 20. Subsequently, as shown in FIG. 3D, the rotation angle displacement of the cam 26 due to the rotation of the cam shaft 24 Ascending further, the control helix 40 formed on the plunger 32 is in communication with the suction / return port 38 on the barrel 36, with the fuel located between the plunger 32 and the delivery valve 18. The delivery is caused by return flow to the control helix 40 which communicates through the bypass hole 42 at a predetermined inclination with the bypass hole 42 extending from the upper center of the upper end of the plunger 32 to the lower side thereof. The valve 18 is elastically connected to the fuel injection nozzle 20 It is formed a series of cycle to block the passage.

In such a relational configuration, the amount of fuel supplied is controlled by the control helix at the point where the effective stroke of the plunger 32, that is, the upper sidewall portion of the plunger 32 for driving the piston blocks the suction / return port 38 by the lift driving. It is determined by the lifting distance of the plunger 32 and the pressure change at that time until 40 is in communication with the suction / return port 38 again.

At this time, the formation direction of the control helix 40 described above forms an inclination angle of a predetermined angle with respect to the longitudinal direction of the plunger 32, and thus the effective stroke distance of the plunger 32 corresponds to the suction / return port 38. It will be in the relationship determined according to the rotation position of 32. As shown in FIG.

Further, the rotational positioning of the plunger 32 is performed by the operation of the accelerator pedal (omitted for the sake of simplicity of the drawing), the rack 52 which drives the sliding drive, and the pinion 54 which is connected to the rack 52 by gears and rotates. The pinion 54 is fixed and rotated so that the sleeve 34 supports the rotational position of the plunger 32.

Therefore, when the user presses the accelerator pedal to increase the output, the effective stroke distance of the plunger 32 forms the distance indicated by L in FIG. 3B, and FIG. 3B in a natural state in which the accelerator pedal is not relatively operated. At the distance indicated by ℓ.

However, as described above, when the user presses the accelerator pedal to increase the output, the plunger 32 supplies the fuel at maximum, but the rotation speed of the engine, that is, the rotation speed of the crankshaft increases gradually. As a result, the fuel supplied is supplied at a corresponding speed or more, which leads to unnecessary waste of fuel, and the oversupply of such fuel does not reach an immediate reaction in the combustion chamber, thereby generating a large amount of unburned soot and nitrogen oxides. .

In addition, the fuel injection pump by the mechanical mechanism is not distinguished between the cold time and the warm time according to the supply of fuel, and is determined by the rotation of the camshaft. This is because the cam shape is formed according to the efficiency in the main operation section. Insufficient improvement measures for the city lowers the engine efficiency at low temperatures, and at the time of idling, the engine is largely affected by the surrounding environment, which causes a lot of relief.

On the other hand, looking at the fuel supply process of the diesel engine by the electronic mechanism, as shown in Figure 4, the fuel contained in the fuel tank (10b) via the fuel filter 14b by the drive of the high pressure supply pump 44, the rail guided into a rail 46 and in a predetermined pressure state, and then atomized into corresponding combustion chambers 22b by a plurality of fuel injectors 48 installed in communication on the rail 46, respectively. Injection is supplied in the state.

Here, the fuel injector described above is provided with an electronic control valve 50 for controlling the fuel injection to the corresponding combustion chamber 22b, the electronic control valve 50 is fueled by a control signal applied from the controller 56 To selectively direct the combustion chamber 22b or the fuel tank 10b.

The supply of fuel by the electronic mechanism is effective in suppressing the generation of a certain amount of fuel and the smoke and denitrification oxides according to the engine speed, but the conversion to the electronic mechanism by the conventional mechanical mechanism For this purpose, there are difficulties such as the replacement of many configurations.

It is an object of the present invention to control fuel supply by the above-described mechanical mechanism at an electronic control level, thereby preventing fuel waste and suppressing noise, soot and generation of nitrogen oxides. To provide a spray system.

1 is a flowchart schematically illustrating a process of supplying fuel by a conventional mechanical mechanism.

FIG. 2 is an exploded perspective view schematically illustrating a structure of the fuel injection pump illustrated in FIG. 1 and an operation relationship between the components.

3A to 3D are cross-sectional views schematically illustrating a cam rotation angle and a pumping relationship between plungers according to time changes.

4 is a flowchart schematically illustrating a process of supplying fuel by an electronic mechanism.

5 is a flowchart schematically illustrating a fuel supply process of a diesel engine according to an embodiment of the present invention.

*** Explanation of symbols for the main parts of the drawing ***

10, 10a: fuel tank 12: fuel supply pump

14, 14a: fuel filter 16, 60: fuel injection pump

18: delivery valve 19, 62: fuel pipe

20: fuel injection nozzle 22, 22a: combustion chamber

24: camshaft 26: cam

28: Return spring 30: Tappet assembly

32, 68: Plunger 34: Sleeve

36: barrel 38: suction / return port

40: Control Helix 42: Bypass Hole

44: high pressure supply pump 46: rail

48: fuel injector 50, 66: electronic control valve

52: rack 54: pinion

56, 72: controller 64: branch pipe

70: pedal detection sensor

In the fuel injection system of the diesel engine according to the present invention for achieving the above object, the pressure of the fuel is supplied to the combustion chamber through the fuel supply pipe and the fuel injection nozzle sequentially by opening the delivery valve driven by the plunger. CLAIMS 1. A fuel supply system of a diesel engine, comprising: a plunger driven by being set to a maximum effective stroke;

A branch pipe branched from the fuel supply pipe to the fuel tank; An electronic control valve which is opened and controlled to guide the flow of fuel to the fuel tank in accordance with a control signal installed in communication on the branch pipe; Pedal detection unit for sensing the operation degree of the accelerator pedal; And a controller configured to receive a detection signal of an engine state including a detection signal applied from the pedal detection unit and apply a control signal to an electronic control valve.

In addition, the electronic control valve is preferably installed on the branch pipe close to the fuel supply pipe, it is preferable that the inner diameter of the branch pipe is formed to be at least the size of the inner diameter of the fuel supply pipe. .

In addition, the plunger may be formed in a single piston shape having no control helix or bypass hole, thereby facilitating its manufacture.

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

5 is a block diagram schematically illustrating a fuel injection system of a diesel engine according to the present invention, and FIG. 6 is a flowchart illustrating a process of supplying fuel according to the configuration of FIG. 5, and the same reference numerals are assigned to the same parts as in the prior art. The detailed description thereof will be omitted.

In the fuel supply system of the diesel engine according to the present invention, as shown in FIG. 5, the fuel contained in the fuel tank 10 is injected through the fuel filter 14 through the fuel filter 14 by driving the fuel supply pump 12. It is pumped to the pump 60 and is driven again by the fuel injection pump 60 to pass through the fuel injection nozzle 20 through the opening of the delivery valve 18 and the fuel pipe 62, and thus inside the combustion chamber 22. At the atomization (atomization) state, the injection supply is made.

Here, a branch pipe 64 for inducing fuel flow to the fuel tank 10 is connected to one side of the fuel pipe 62 described above, and the fuel pipe 62 is described above on the branch pipe 64. An electronic control valve 66 is installed to control the opening and closing of the fuel flow through the branch pipe 64 in close proximity to the branched portion from).

On the other hand, the configuration of the above-described fuel injection pump 60 is a part of the fuel injection supply process by the conventional mechanical mechanism and the same operation process, but in the case of the plunger 68 of the prior art configuration related to the fuel supply amount control The configuration related to the sleeve 34 and the pinion 54 and the rack 52 is not required of the prior art configuration which is always set to the maximum effective stroke position and determines the effective stroke position of the plunger 68, It is fixed at the maximum effective stroke position of the plunger 68.

Accordingly, the technical configuration of the plunger 68 can be replaced by a single rod-shaped piston in which the control helix 40 and the bypass hole 42 according to the prior art configuration are not formed.

In addition, the operation of the accelerator pedal (omitted for the sake of simplicity of the drawing) for controlling the amount of fuel supplied further includes a pedal sensor 70 for detecting the degree of operation of the accelerator pedal, the pedal sensor 70 Is applied to the controller 72 the operation degree detection signal of the accelerator pedal by the user.

In addition, the above-described controller 72 is a signal of the pedal detection sensor 70 and the sense signal of each part related to the driving of the engine, such as the rotation angle of the crankshaft (omitted for simplicity of the drawing) and the temperature of the engine. Based on the determination, the fuel supply amount of the appropriate amount is determined, and from this determination, the predetermined amount of the fuel pumped to the fuel injection nozzle 20 by the fuel injection pump 60 is controlled by controlling the driving of the above-described electronic control valve 66. Bypass 64 to the fuel tank (10).

At this time, the control signal applied from the controller 72 to the electronic control valve 66 is periodically applied to at least one subdivided pulse signal for one rotation of the crankshaft to continuously and repeatedly open and close the degree of the electronic control valve 66 To control.

Therefore, according to the present invention, the fuel supply amount according to the mechanical mechanism is controlled and supplied to the appropriate supply amount through the detection of the state of the engine such as the rotation angle of the speed crankshaft of the engine and the temperature of the engine, thereby reducing the waste of fuel, according to the smoke and nitrogen Oxide emissions can be reduced, resulting in the advantage of stable engine operation and efficiency.

Although the present invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical scope of the present invention, and such modifications and modifications are within the scope of the appended claims.

Claims (4)

In the fuel supply system of a diesel engine, in which the fuel under pressure is supplied to the combustion chamber sequentially through the fuel supply pipe and the fuel injection nozzle by opening the delivery valve by driving the plunger, A plunger which is set to a maximum effective stroke and is driven; A branch pipe branched from the fuel supply pipe to the fuel tank; An electronic control valve which is opened and controlled to guide the flow of fuel to the fuel tank according to a control signal which is installed and communicated on the branch pipe; Pedal detection unit for sensing the operation degree of the accelerator pedal; And And a controller configured to receive a detection signal of an engine state including a detection signal applied from the pedal detection unit, and apply a control signal to an electronic control valve. The method of claim 1, The electronic control valve is a fuel supply system of the diesel engine, characterized in that installed on the branch pipe adjacent to the fuel supply pipe. The method of claim 1, The inner diameter of the branch pipe is connected to at least the size of the inner diameter of the fuel supply pipe in communication with the diesel engine, characterized in that made. The method of claim 1, The plunger is a fuel supply system of the diesel engine, characterized in that formed in the shape of a piston having no control helix or bypass hole.