KR20140001432A - Direct injection type liquefied petroleum-gas injection system - Google Patents

Abstract

The present invention relates to a direct injection LPI system including: a fuel pump which pumps and supplies fuel to an engine by being installed inside a cylinder; a high pressure pump which pressurizes a part of the fuel pumped and supplied by the fuel pump at high pressure and delivers remaining fuel to a fuel collecting line in order to collect the fuel in the cylinder; a delivery pipe which is connected to the high pressure pump and is filled with the fuel pressurized by the high pressure; an injector which is connected to the delivery pipe and directly injects the fuel of liquid state filled by the high pressure to the inside of a combustion chamber; an electronic control unit which controls the driving of the injector in order to directly inject the fuel pressurized by the high pressure pump to the inside of the combustion chamber based on the target RPM of the engine; and a bypass line which circulates the fuel filled in the delivery pipe to the front end of the high pressure pump of the fuel supply line. By using the direct injection LPI system like the forementioned, the present invention prevents an engine abnormality and a start-off which are caused by vaporization of LPG fuel by circulating fuel supplied to the delivery pipe with the high pressure pump through the bypass line. [Reference numerals] (18) Motor controller

Description

DIRECT INJECTION TYPE LIQUEFIED PETROLEUM-GAS INJECTION SYSTEM}

The present invention relates to a direct injection Elpiy system, and more particularly, to pressurize the LPG fuel to a high pressure directly to the engine to improve the power performance of the vehicle, improve fuel efficiency, and reduce the amount of carbon generated Direct injection Elpia is about this system.

In recent years, a direct injection Elpia system has been developed, which pressurizes the LPG fuel to a high pressure and directly sprays it into the cylinder of the engine.

The direct injection Elpiai system has the effect of improving the power performance of the vehicle, reducing fuel consumption, improving fuel economy, and reducing carbon emissions.

The present applicant has filed and disclosed a direct injection Elpia system in Korean Patent Application No. 10-2009-0070720 (filed on July 31, 2009, hereinafter referred to as 'Patent Document 1').

1 is a configuration diagram of a direct injection Elpii system according to Patent Document 1.

As illustrated in FIG. 1, the direct injection ELP system according to Patent Document 1 includes a cylinder 1 in which fuel is stored, a fuel pump 3 installed in the cylinder 1, and a fuel pump 3 and a fuel pump 3. Fuel supply line (S) for supplying the pumped fuel to the engine (E), the fuel recovery line (R), the fuel recovery line (R) for recovering the fuel of the engine (E) to the cylinder (1) A high pressure pump 7 for pressurizing the fuel pumped from the fuel pump 3 to a high pressure to supply the engine E, and a delivery pipe 9 connected to the discharge side of the high pressure pump 7 to fill the pressurized fuel at high pressure. And a high pressure regulator 8 in which the pressure of the fuel is kept constant in the high pressure state in the delivery pipe 9.

The injector I which directly injects the fuel filled with the delivery pipe 9 at high pressure into the combustion chamber of the engine E is connected through a connecting pipe from the delivery pipe 9, and the spark plug is connected to the cylinder head of the engine E. It is mounted adjacent to (P).

In addition, a shutoff valve SV is installed at the front end of the high pressure pump 7 in the fuel supply line S, and the high pressure pump 7 is pumped from the fuel pump 3 and transferred to the fuel supply line S. Press to 100 ~ 200bar.

The high pressure regulator 8 ensures that the pressure of the fuel injected through the injector I is kept constant in the delivery pipe 9 at a high pressure, for example, about 120 bar, and further overflows the pressure to the cylinder 1. It has a function to make a recall.

The fuel recovered from the high pressure regulator 8 is reduced in pressure by the fuel pressure regulator 6 and then recovered into the cylinder 1.

Accordingly, the direct injection ELPAI system according to Patent Document 1 maintains the liquid fuel level in the cylinder properly by recovering the fuel remaining in the engine or the fuel overflowed from the high-pressure regulator, and the empty space inside the cylinder is suddenly reduced. It is possible to prevent the increase and to suppress the cavitation to achieve the thermal equilibrium state.

In other words, the direct injection Elpiai system according to Patent Document 1 reduces the pressure of the fuel recovered through the fuel pressure regulator to recover to the cylinder, but since the fuel recovered to the cylinder is still at a high temperature, the temperature of the entire Elpji fuel stored in the cylinder Rises.

Accordingly, the direct injection ELP system according to Patent Document 1 has a problem that cavitation occurs during pressurized delivery of fuel while the LPG fuel is changed into a gaseous state inside the bombe.

In addition, Patent Document 1 has a high-pressure regulator for maintaining a constant fuel pressure of the delivery pipe and a fuel pressure regulator for reducing the pressure of the recovered fuel, thereby increasing the number of parts, which complicates the construction of the direct injection Elpia system. There was a problem of rising costs.

In addition, the conventional direct injection ELPI system including Patent Document 1, as the fuel delivered from the high pressure pump to the delivery pipe is continuously maintained in the fuel supply line and the inside of the delivery pipe, the temperature of the Lizzy fuel by the heat of the engine. Vaporizes as it rises.

As described above, the conventional direct injection ELP system has a problem in that the fuel pressure is increased while vaporizing the LLP fuel filled in the fuel supply line and the delivery pipe, and thus fuel delivery from the high pressure pump is impossible.

For this reason, the conventional direct injection Elpia system has a problem that it is impossible to normal fuel supply to the engine, the engine relief and starting off phenomenon occurs.

Republic of Korea Patent Application No. 10-2009-0070720 (filed July 31, 2009)

The present invention is to solve the problems as described above, an object of the present invention is to provide a direct injection Elpiai system for direct injection into the engine by pressurizing the pressure of the liquid lipji fuel in the high pressure.

It is another object of the present invention to provide a direct injection Elpia system that circulates the Elpji fuel supplied to the delivery pipe with a high pressure pump to prevent the temperature rise of the fuel due to the heat of the engine.

Another object of the present invention is to directly recover the vellum fuel circulated to the high pressure pump after being supplied to the delivery pipe back to the cylinder to prevent the cavitation inside the cylinder caused by the temperature rise of the levitation fuel to directly supply the pleasing fuel to the engine Injection Elpia is to provide this system.

According to a feature of the present invention for achieving the above object, the present invention is a direct injection Elpia system for directly injecting the liquid lipid fuel in the cylinder into the combustion chamber of the engine, in the interior of the cylinder To pump the fuel and supply the fuel to the engine, a high pressure pump for supplying a portion of the fuel pumped by the fuel pump to a high pressure and transferring the fuel to a fuel recovery line to recover the remaining fuel to the cylinder; A delivery pipe connected to the pressurized fuel to be filled with high pressure, an injector connected to the delivery pipe and directly injecting the liquid fuel filled with high pressure into the combustion chamber, and pressurized from the high pressure pump based on a target RPM of the engine. Drive the injector to inject the spent fuel directly into the combustion chamber. A control electronic control unit and the fuel filled in the inside of the delivery pipe, which comprises a bypass line to the high-pressure pump for circulating the front end of the fuel supply line.

The present invention is installed at the front of the high pressure pump of the fuel supply line and the rear end of the high pressure pump of the fuel recovery line to reduce the pressure of the fuel recovered from the low pressure portion of the high pressure pump to the cylinder and to supply a constant amount of fuel supplied to the high pressure pump. It characterized in that it further comprises a regulator unit for maintaining.

The high pressure pump is a body, a pressure means for pressurizing a part of the fuel supplied from the bomb through the inlet formed on one side of the body to a high pressure and a low pressure state before being pressed by the pressurization means from the fuel introduced through the inlet And a low pressure portion for delivering the remaining fuel to the fuel recovery line, wherein the low pressure portion is a path for delivering the low pressure fuel introduced through the inlet to the fuel recovery line via a damper for reducing the pulsation of the fuel. It is characterized by.

The pressurizing means is provided inside the body to generate a suction force and a pressing force of the fuel piston and return spring, a spill valve coupled to the inlet to control the supply flow rate and discharge pressure of the fuel, the inlet side connected to the spill valve And a discharge side check valve coupled to a check valve and a discharge hole for discharging the fuel pressurized by the piston.

As described above, the present invention can circulate the fuel supplied to the delivery pipe through the bypass line with a high-pressure pump to prevent engine relief and start-up due to the vaporization of the LPG fuel.

In addition, the present invention can prevent the vaporization of the fuel supplied to the combustion chamber of the engine by supplying the fuel pressurized by the high-pressure pump to the delivery pipe by the same amount as the injection amount injected through the injector to maintain a high pressure inside the delivery pipe. have.

Accordingly, the present invention eliminates the high-pressure regulator provided to maintain the pressure of the fuel overflowed in the delivery pipe in the conventional direct injection Elpia system at a high pressure to simplify the configuration of the system and reduce the manufacturing cost Can be.

In addition, the present invention is to recover some of the fuel supplied to the high-pressure pump from the low pressure portion of the high-pressure pump by the continuous pumping operation of the fuel pump to maintain the thermal equilibrium inside the cylinder to keep the Elpji fuel due to the fuel temperature rise inside the cylinder To prevent vaporization.

Accordingly, the present invention can improve the pump efficiency by minimizing the cavitation caused by the vaporization of the vellum fuel in the pressurized delivery process of the fuel, it is possible to smoothly supply the lpgi fuel to the engine.

As a result, the present invention directly injects the high-pressure liquid liquid LPG fuel into the engine, and recovers the remaining fuel under low pressure to the cylinder before supplying it to the engine, thereby reproducing the power performance of the vehicle similar to the direct injection method of gasoline fuel. Improve fuel economy and reduce the amount of carbon generated.

1 is a configuration diagram of an Elpiai system according to the prior art,
2 is a block diagram of a direct injection Elpiyi system according to a preferred embodiment of the present invention,
3 is a perspective view of the high pressure pump shown in FIG.
4 is a cross-sectional view taken along line AA ′ of FIG. 3;
FIG. 5 is a cross-sectional view taken along line BB ′ shown in FIG. 3. FIG.

Hereinafter, the direct injection Elpia system according to the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a configuration diagram of a direct injection ELPIA system according to a preferred embodiment of the present invention, FIG. 3 is a perspective view of the high pressure pump shown in FIG. 2, and FIG. 4 is a line A-A 'shown in FIG. 3. 5 is a cross-sectional view taken along line BB ′ shown in FIG. 3.

In this embodiment, the fuel supplied through the fuel supply line (S) by the pumping operation of the fuel pump 12 at the start of the engine is initially delivered to the high pressure pump 14 at a constant pressure, for example, a pressure of about 2 bar. Likewise, the fuel pressure supplied at the start of the start is called a 'low pressure state'.

In addition, the transfer path for transferring the low-pressure LPG fuel from the inlet 21 of the high pressure pump 14 to the fuel recovery line R through the damper 25 is referred to as a 'low pressure part 30'.

As illustrated in FIG. 2, the direct injection Elpia system according to the preferred embodiment of the present invention is installed in a cylinder 11 in which fuel is stored, a fuel pump 12 installed in the cylinder 11, and a fuel pump 12. A fuel supply line S for supplying the fuel pumped from the engine 12 to the engine E, a high pressure pump 14 for pressurizing the fuel pumped by the fuel pump 12 to a high pressure, and a high pressure pump 14 A fuel recovery line (R) for recovering a portion of the used fuel from the low pressure portion of the high pressure pump (14) to the cylinder (11), a delivery pipe (15) and a delivery pipe in which the fuel pressurized from the high pressure pump (14) is filled with high pressure. The injector I which directly injects fuel filled at 9 into the combustion chamber of the engine E, the motor and the injector I in the fuel pump 12 based on the target RPM of the engine E. The motor and the motor according to the control signals of the ECU 17 and the ECU 17 which generate a control signal for controlling the driving. A motor controller 18 for controlling the driving of the projector (I).

And the front of the high pressure pump 14 of the fuel supply line (S) and the rear end of the high pressure pump 14 of the fuel recovery line (R) of the fuel recovered from the low pressure portion 30 of the high pressure pump 14 to the cylinder 11 A regulator unit 16 is installed to reduce the pressure and keep the supply amount of fuel supplied to the high pressure pump 14 constant.

Although not shown in the drawing, the regulator unit 16 includes a fuel pressure regulator, a gas pressure measuring sensor, a gas temperature measuring sensor, and a shutoff valve, and through this, a fuel supply line S and a fuel recovery line R are provided. To control fuel supply and shutdown.

The fuel pump 12 pumps the LLP fuel stored in the cylinder 11 and supplies it to the fuel supply line S. At this time, the fuel supplied through the fuel supply line S is initially delivered to the high pressure pump 14 at a low pressure, for example, a pressure of about 2 bar.

The high pressure pump 14 is pumped by the fuel pump 12 to supply a portion of the fuel supplied to the low pressure through the fuel supply line (S) to a high pressure, for example about 40 ~ 150 bar to supply to the delivery pipe 15, The remaining fuel is to be recovered to the cylinder 11 through the fuel recovery line (R) from the low pressure portion 30 therein.

In particular, the fuel supply line (S) connected to the front end of the high-pressure pump 14 is connected through the delivery pipe 15 and the bypass line (B) to circulate some of the fuel supplied to the delivery pipe (15). .

That is, one end of the bypass line (B) is connected to the rear end of the delivery pipe 15, the other end of the bypass line (B) is connected to the front end of the high-pressure pump 14 of the fuel supply line (S).

Accordingly, the present invention can circulate some of the fuel supplied to the delivery pipe through the bypass line to the high-pressure pump again to prevent the temperature and pressure rise of the fuel due to heat of the engine.

Referring to Figures 3 to 5 will be described in detail the structure of the high pressure pump.

3 to 5, the inlet 21 and the outlet 22 are formed on the side of the body 20 forming the outer shape of the high-pressure pump 14, the fuel of the inside of the body 20 A piston 23 and a return spring 24 are provided as a pressurizing means for generating suction force and a pressing force, and a damper portion 25 for reducing pulsation of fuel is mounted on the upper portion of the body 20.

The inlet 21 has a spill valve 26 for controlling the supply flow rate and the discharge pressure and an inlet check valve 27 connected to the spill valve 26, and a discharge check valve 28 is coupled to the outlet 22. do.

A plurality of valleys 251 are formed on the inner surface of the damper portion 25 to reduce pulsation of the fuel, and a connection hole 252 connected to the low pressure portion 30 is formed on the side of the damper portion 25.

When the engine E is driven, the high pressure pump 14 receives the engine driving force in conjunction with a camshaft (not shown) to operate the pumping operation.

And the fuel pump 12 and the high pressure pump 14 is preferably provided as a volumetric pump using a piston 23, a diaphragm, gears, vanes and the like, as shown in FIG.

Impeller-type pumps, such as turbine pumps, have a positive pressurizing capacity in the pressurization process using two pumps, but the fuel pump 12 and the high-pressure pump 14, which are provided as a volumetric pump, have each pump 12, It can represent the effect of the pressure capacity multiplied by the pumping capacity of 14).

According to the experimental value, the high pressure pump 14 pumps about 95% of the fuel pumped by the fuel pump 12 and supplied to the high pressure pump 14 when the engine E is idle. ) To recover to the cylinder 11, and during the normal operation of the engine (E) to recover about 60% of the fuel to the cylinder (11).

In the fuel pressure regulator of the regulator unit 16, the pressure of the fuel recovered from the low pressure portion 30 of the high pressure pump 14 to the cylinder 11 is reduced from the low pressure state (2 bar) by the continuous pumping operation of the fuel pump 12. When a predetermined pressurization pressure, for example, Δ5bar is pressed to about 7bar, an internal valve is opened to deliver fuel to the cylinder 11.

When the pressure inside the fuel is lower than about 7 bar as the fuel is delivered to the cylinder 11 through the open valve, the pressure inside the fuel pressure regulator 16 is higher than about 7 bar after closing the valve. Repeat the opening operation.

The pressurized pressure is a pressure set in advance to pressurize the fuel recovered to the cylinder 11 to achieve thermal equilibrium in the cylinder 11 to prevent vaporization.

Accordingly, in the cylinder 11, thermal equilibrium is achieved by the fuel discharged by the fuel pump 12 and the fuel recovered from the high pressure pump 14.

In detail, the fuel stored in the cylinder 1 is discharged by the fuel in the cylinder 1 in the conventional Elpia system, but the liquid stored in the cylinder 1 remains in the liquid state, but vaporization occurs in the space above the cylinder 1. The internal saturated vapor pressure is lowered.

As a result, the internal temperature of the cylinder 1 is drastically lowered, the fuel is more easily vaporized, and as the cavitation occurs in the first pumping process, the fuel delivery capacity of the fuel pump 3 is significantly reduced.

On the other hand, in the present invention to achieve a heat balance inside the cylinder by recovering the appropriate amount of fuel through the fuel recovery line.

That is, the present invention can maintain the level of the liquid fuel in the cylinder appropriately by immediately recovering fuel from the low pressure portion of the high pressure pump, and can suppress cavitation by preventing the empty space inside the cylinder from rapidly increasing. .

In particular, the present invention can maintain the temperature of the fuel in a low temperature state by recovering the fuel in a low pressure state before supplying to the delivery pipe through the high pressure pump can maintain a constant temperature inside the cylinder.

Accordingly, the inside of the cylinder 11 is to maintain the thermal equilibrium state. As such, when the thermal equilibrium is made in the cylinder 11, the pressurized delivery process of the fuel may be smoothly performed, and thus, the performance of the LLP fuel supply system may be best exhibited.

The amount of fuel recovered may be controlled to an amount necessary for thermal balance through an appropriate evaluation according to the size of the cylinder 11, the displacement of the vehicle.

On the other hand, as the fuel of the same amount as the injection amount of the fuel injected through the injector I is supplied to the delivery pipe 15 in a state of being pressurized to a high pressure by the high pressure pump 14, the pressure inside the delivery pipe 15 It is maintained at a constant high pressure, that is about 40 ~ 150bar.

As described above, in the delivery pipe 15 maintained at a high pressure, vaporization of the fuel is suppressed due to the high pressure, so that the LLP fuel supplied to the combustion chamber of the engine E through the injector I is maintained in the liquid state.

In particular, some of the fuel filled in the delivery pipe is circulated through the bypass line to the fuel supply line while the temperature and the pressure raised by the heat of the engine are lowered to maintain the liquid state. Will be lowered.

The present invention is to recover some of the fuel supplied to the high pressure pump to the cylinder by the continuous pumping operation of the fuel pump to maintain the thermal equilibrium inside the cylinder to maintain the thermal equilibrium of the fuel oil due to the fuel temperature rise inside the cylinder Prevent vaporization

Accordingly, the present invention improves pump efficiency by minimizing cavitation generated by vaporization of LLP fuel in pressurized delivery of fuel, and smoothly supplies fuel to improve vehicle power performance and fuel economy, and reduce carbon generation amount. You can get the effect.

In addition, the present invention circulates some of the fuel supplied to the delivery pipe to the high pressure pump to prevent the temperature and pressure rise of the fuel due to the heat of the engine to prevent the engine relief and starting off due to the vaporization of the fuel.

On the other hand, the first and second pressure sensors for detecting the fuel pressure to check the moving fuel pressure in the front of the high pressure pump 14 of the fuel supply line (S) and the rear of the high pressure pump 14 of the fuel recovery line (R). (Not shown) is preferably provided, and the delivery pipe 15 is preferably provided with a third pressure sensor (not shown).

The ECU 17 is a shut-off valve, fuel pump 12, multi-valve 13 and fuel pressure regulator in accordance with the fuel pressure detected from the first and second pressure sensors and the third pressure sensor installed in the delivery pipe 15. A control signal is generated in the motor controller 18 to control the driving of the motor.

Next, a method of operating the direct injection Elpia system according to a preferred embodiment of the present invention will be described in detail.

When the ignition key (not shown) is operated to supply power, the ECU 17 drives the motor embedded in the fuel pump 12 and opens the shutoff valve of the regulator unit 16. A control signal for controlling the driving and a control signal for controlling the driving of the spark plug P and the injector I are generated to rotate the engine E to the target RPM.

Accordingly, the fuel pump 12 inside the cylinder 11 is driven to pump fuel stored in the cylinder 11 and supplied through the fuel supply line S, and the shutoff valve is supplied with a high pressure pump ( 14) open operation to be delivered.

At this time, since the inside of the delivery pipe 15 is filled with a high-pressure liquid of the liquid oil, the injector I and the spark plug P are driven in accordance with the control signal of the ECU 17 to drive the engine E. do.

Then, the high pressure pump 14 is driven using the driving force of the engine in conjunction with the camshaft of the engine E, pressurizes a part of the fuel supplied through the shutoff valve to a high pressure to deliver to the delivery pipe 15, the rest The fuel is transferred to the fuel recovery line R through the connection hole 252 of the damper part 25, which is the low pressure part 30.

At this time, as the valve inside the fuel pressure regulator of the regulator unit 16 is opened and closed, fuel pressurized by about Δ5 bar, which is a pressurized pressure, is recovered to the cylinder 11 through the fuel recovery line R.

Accordingly, in the cylinder 11, thermal equilibrium is achieved between the fuel pumped and discharged by the fuel pump 12 and the fuel pressurized and recovered by the fuel pressure regulator 16.

Meanwhile, according to the control signal of the ECU 17, the high-pressure fuel in the injector I is directly injected into the combustion chamber of the engine E as the high pressure liquid is directly injected into the combustion chamber of the engine E. Supplied to (15).

As such, since the delivery pipe 15 always maintains a high pressure state, the fuel inside the delivery pipe 15 may maintain a liquid state.

However, as the engine temperature increases due to the driving of the vehicle, the temperature of the fuel filled in the delivery pipe also increases.

Thus, the bypass line B circulates some of the fuel supplied to the delivery pipe 15 to the high pressure pump 14 to lower the temperature and pressure of the fuel.

Accordingly, the ECU 17 precisely controls the injection amount of the high-pressure liquid Ellipse fuel injected into the combustion chamber of the engine E to improve the power performance and fuel economy of the vehicle, similar to the direct injection method of gasoline fuel, The amount of carbon generated can be reduced.

Through the process as described above, the present invention circulates the fuel supplied to the delivery pipe through the bypass line with a high pressure pump to prevent engine relief and starting off due to the vaporization of the LPG fuel.

Although the present invention has been described in detail with reference to the above embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

The present invention is a direct injection Elpii system that pressurizes the liquid state of the LPG fuel to a high pressure directly circulating the fuel filled inside the delivery pipe through a bypass line in a high-pressure pump in the system of the direct injection Elpia by the heat of the engine vaporization Technology to prevent engine relief and starting off by preventing

10: Direct Injection Elpiai System 11: Bombe
12: fuel pump 13: multi-valve
14: high pressure pump 15: delivery pipe
16: Regulator Unit 17: ECU
18: motor controller 20: body
21: inlet 22: outlet
23: piston 24: return spring
25: damper portion 251: goal
252: connection hole 26: spill valve
27: inlet check valve 28: discharge check valve
30: low pressure part S: fuel supply line
R: Fuel recovery line B: Bypass line

Claims (4)

In the direct injection Elpiai system that directly injects the liquid Elfiji fuel in the cylinder into the combustion chamber of the engine,
A fuel pump built in the cylinder to pump fuel and supply it to an engine;
A high pressure pump which presses a part of the fuel pumped and supplied by the fuel pump to a high pressure and delivers the remaining fuel to the cylinder;
A delivery pipe which is connected to the high pressure pump and filled with fuel pressurized at high pressure;
An injector connected to the delivery pipe and directly injecting the liquid fuel filled at high pressure into the combustion chamber;
An electronic control unit for controlling the driving of the injector to directly inject the fuel pressurized from the high pressure pump into the combustion chamber based on the target RPM of the engine;
And a bypass line for circulating the fuel filled in the delivery pipe to the front of the high pressure pump of the fuel supply line. The method of claim 1,
It is installed at the front of the high pressure pump of the fuel supply line and the rear of the high pressure pump of the fuel recovery line to reduce the pressure of the fuel recovered from the low pressure portion of the high pressure pump to the cylinder and to maintain a constant supply amount of the fuel supplied to the high pressure pump. Direct injection Elpiay system further comprises a regulator unit. The method of claim 1 or 2, wherein the high pressure pump
body,
Pressing means for pressurizing a portion of the fuel supplied from the bomb through the inlet formed on one side of the body at high pressure;
Among the fuel introduced through the inlet comprises a low pressure portion for delivering the remaining fuel in the low pressure state before being pressed by the pressurizing means to the fuel recovery line,
The low pressure portion is a direct injection Elpia system, characterized in that the path for passing the low-pressure fuel flowing through the inlet to the fuel recovery line via a damper for reducing the pulsation of the fuel. The method of claim 3, wherein the pressing means
A piston and a return spring provided inside the body to generate a suction force and a pressing force of the fuel,
A spill valve coupled to the inlet to control a supply flow rate and a discharge pressure of the fuel;
An inlet check valve connected to the spill valve;
And a discharge side check valve coupled to the discharge hole for discharging the fuel pressurized by the piston.

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