KR20170011832A - Liquid petroleum-gas direct injection system - Google Patents

Abstract

The present invention relates to a direct spray type liquid propane injection (LPI) system. The direct spray type LPI system includes: a fuel pump which pumps the fuel stored in a bomb unit to supply the fuel to the engine to directly spray the LPG fuel stored in the bomb unit in the liquid form directly into the combustion chamber of an engine; a high-pressure fuel pump which presses a part of the fuels pumped by the fuel pump and supplied through the fuel supply line at a high pressure and transmits the remaining fuel to a fuel restoring line to restore the fuel in the bomb unit; a shutoff valve which is installed on a fuel restoring line and opens or closes the fuel restoring line; and an electronic control unit which controls the shutoff valve to close for a preset period to cut off the fuel restoration through the fuel restoring line when an engine starts. When the engine starts, the shutoff valve operates to block the fuel restoring line for restoring the fuel to the bomb unit from the high-pressure fuel pump for a preset time to press the entire fuel at the high pressure and supply the fuel to the engine, thereby enhancing the engine starting performance.

Description

[0001] LIQUID PETROLEUM-GAS DIRECT INJECTION SYSTEM [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0002] The present invention relates to a direct injection type ELF system, and more particularly, to a direct injection type ELF system in which an ELF fuel is pressurized at a high pressure and injected directly into an engine.

In general, the direct injection type Liquid Petroleum Direct Injection is a system in which a high-pressure fuel pump is installed in a fuel supply line, unlike a mechanical type LPG fuel system which depends on the pressure of a fuel tank, Fuel is injected from the injector into the cylinder to drive the engine.

This direct injection type Elfia system improves the power performance of a vehicle, reduces fuel consumption, improves fuel economy, and reduces carbon emissions.

The applicant of the present invention has already filed a patent application for direct injection type Elpiae system in many of the following Patent Documents 1 and the like.

FIG. 1 is a configuration diagram of a direct injection type ELPHI system according to Patent Document 1. FIG.

Patent Document 1 discloses, as shown in Fig. 1, a fuel pump 2 for pumping fuel, a cylinder 1 for storing fuel, a fuel pump 2 for pumping fuel, a fuel pump 2, E), a fuel recovery line R for recovering the fuel of the engine E to the cylinder 1, a fuel supply line S provided on the fuel supply line S and pumped by the fuel pump 2, A delivery pipe 4 connected to the discharge side of the high pressure pump 3 and filled with fuel pressurized at a high pressure, and a delivery pipe 4 connected to the discharge side of the high pressure pump 3, Pressure regulator 5 that keeps the high-pressure regulator 5 constantly in the high-pressure state in the high-pressure state.

The injector I injecting fuel injected into the delivery pipe 4 at a high pressure directly into the combustion chamber of the engine E is connected through a connection pipe from the delivery pipe 4 and is connected to the cylinder head of the engine E via a spark plug (P).

A shutoff valve SV is provided at the front end of the high pressure pump 3 in the fuel supply line S and the high pressure pump 3 is connected to the fuel Is pressurized to about 100 to 200 bar.

The high-pressure regulator 5 allows the pressure of the fuel injected through the injector I to remain constant in the delivery pipe 4 at a high pressure state, for example, about 120 bar, To be retrieved.

Here, the fuel recovered from the high-pressure regulator 5 is decompressed by the fuel pressure regulator 7 and then returned to the bomb case 1.

Accordingly, the direct injection type Elpia system according to Patent Document 1 properly maintains the liquid fuel level in the cylinder by recovering the fuel remaining in the engine or the fuel overflowed from the high-pressure regulator to the cylinder, So that cavitation is suppressed to achieve a thermal equilibrium state.

That is, the direct injection type Elfia system including Patent Document 1 is a system in which a low-pressure fuel portion for supplying the LPG stored in the cylinder to a high-pressure fuel pump at a pressure of about 5 bar and supplying the remaining fuel to the delivery pipe, And a high-pressure fuel portion for supplying the high-pressure fuel pressurized at about 40 to 100 bar to the injector through the delivery pipe.

Korean Patent Publication No. 10-2011-0012836 (published on Feb. 9, 2011)

On the other hand, the direct injection type ELISA system according to the prior art has many weaknesses depending on the temperature of the outside according to the use of the LPG fuel.

That is, in the direct injection type Elpia system according to the related art, vaporization and compression are caused due to the characteristics of the LPG fuel at low temperature and high temperature conditions, there is a problem that the startup delay and instability of the idle state occur.

Particularly, the direct injection type ELISA system according to the related art has a problem in that the startability in low temperature and high temperature conditions is lowered according to the external temperature condition.

Therefore, an object of the present invention is to provide a direct injection type ELISA system that pressurizes liquid state LPG at a high pressure and directly injects it into an engine.

Another object of the present invention is to provide a high pressure fuel pump which is capable of recovering the bubbles containing bubbles into the bomb by the heat generated from the flow control valve provided in the high pressure fuel pump and preventing the formation of abnormal pressure due to bubbles contained in the liquefied fuel, The present invention provides a direct injection type ELISA system capable of improving the performance of a direct injection type ELISA system.

It is still another object of the present invention to provide a direct injection type ELISA system capable of improving the starting performance of an engine by shutting off a fuel recovery line for recovering fuel from a high-pressure fuel pump to a cylinder at the time of starting the engine.

In order to achieve the above-mentioned object, the direct injection type ELFi system according to the present invention is built in the cylinder to inject the liquid state LPG fuel injected into the cylinder directly into the combustion chamber of the engine, A high-pressure fuel pump that pumps a portion of the fuel pumped by the fuel pump through the fuel supply line to a high pressure and delivers the remaining fuel to the fuel recovery line to recover the fuel to the cylinder, And an electronic control unit for controlling the shut-off valve to shut off the fuel shut-off valve for a preset time so as to shut off the fuel recovery through the fuel return line at the start of the engine. do.

As described above, according to the direct injection type ELFi system of the present invention, among the fuel sucked into the inside of the body through the inlet-side check valve of the high-pressure fuel pump, the gas is vaporized by the heat due to the operation of the flow control valve, The effect of being able to form a high pressure by sufficiently pressurizing the remaining amount of the LPF at a predetermined high pressure by recovering the contained LPF through the recovery port before pressurizing the LPF from the low pressure state to the high pressure.

Thus, according to the high-pressure fuel pump for the direct injection type ELFI system according to the present invention, it is possible to improve the restartability of the vehicle to which the direct injection type ELF system is applied after restarting at constant speed.

According to the present invention, when the engine is started, the shutoff valve is operated to shut off the fuel recovery line for recovering the fuel from the high-pressure fuel pump to the bomb for a preset time period so as to pressurize the entire fuel to the high pressure and supply it to the engine. The effect of improving the performance can be obtained.

That is, according to the present invention, as the fuel recovery line is shut off at the time of starting the engine, the whole fuel supplied to the high-pressure fuel pump is pressurized by the high-pressure fuel pump and supplied to the injector, .

According to the present invention, since the shutoff valve is opened after the engine is started to recover some of the fuel to the cylinder, the temperature inside the high-pressure fuel pump is lowered to smoothly supply the fuel to the high-pressure fuel portion and the low- An effect that can be improved is obtained.

FIG. 1 is a configuration diagram of a direct injection type ELFI system according to a first embodiment of the present invention,
FIG. 2 is a perspective view of the high-pressure fuel pump shown in FIG. 1,
3 is a cross-sectional view taken along line A-A 'of the high-pressure fuel pump shown in FIG. 2,
4 is a cross-sectional view taken along the line B-B 'shown in FIG. 2,
5 is a perspective view showing a modified example of the high-pressure fuel pump,
FIG. 6 is a configuration diagram of a direct injection type ELFI system according to a second embodiment of the present invention,
FIGS. 7 and 8 are graphs for evaluating the start-up performance of the direct injection type ELPIP system according to the first and second embodiments, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a high-pressure fuel pump for a direct injection type ELFi system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, the fuel supply line for supplying the LPG stored in the cylinder to the high-pressure fuel pump at a pressure of about 5 bar and the fuel recovery line for recovering the remaining fuel supplied from the high-pressure fuel pump to the delivery pipe are referred to as low-pressure fuel.

The delivery pipe and the injector, which supply the high-pressure fuel pressurized at about 40 to 100 bar from the high-pressure fuel pump to the engine, are referred to as a high-pressure fuel portion.

FIG. 1 is a configuration diagram of a direct injection type ELISA system according to the first embodiment of the present invention.

In the present embodiment, the fuel supplied through the fuel supply line S by the pumping operation of the fuel pump 12 at the time of engine startup is initially delivered to the high-pressure fuel pump 14 at a predetermined pressure, for example, a pressure of? Similarly, the fuel pressure supplied at the start of the engine is referred to as a "low-pressure state".

The transfer path for transferring the low-pressure LPG fuel from the intake port of the high-pressure fuel pump 14 to the fuel recovery line R through the recovery port is referred to as a "low-pressure section 30 (see FIG. 3)".

1, the direct injection type ELF i system 10 according to the first embodiment of the present invention includes a cylinder 11 in which a fuel is stored, a fuel pump 12 A fuel supply line S for supplying fuel pumped by the fuel pump 12 to the engine E, a high-pressure fuel pump 14 for pressurizing the fuel pumped by the fuel pump 12 to high pressure, A fuel recovery line R for collecting a part of the fuel supplied to the high pressure fuel pump 14 from the low pressure portion 30 of the high pressure fuel pump 14 to the cylinder 11, A pipe 15 and an injector I for directly injecting the fuel filled in the delivery pipe 15 into the combustion chamber of the engine E and a motor RPM in the fuel pump 12 based on the target RPM of the engine E, And an ECU 17 (hereinafter referred to as " ECU ") 17 for generating a control signal for controlling the driving of the injector I, And a motor controller 18 for controlling the driving of the motor in accordance with a control signal of the motor controller 18.

The fuel supply line S is opened and closed in response to the drive signal of the motor controller 18 based on the control signal from the ECU 17 to the front end of the high pressure fuel pump 14 to shut off the fuel supplied from the cylinder 11 A valve SV is provided at a downstream end of the high pressure fuel pump 14 of the fuel recovery line R and a fuel for reducing the pressure of the fuel recovered from the low pressure portion 30 of the high pressure fuel pump 14 to the cylinder 11 A pressure regulator 16 may be installed.

The fuel pump 12 pumps the LPG stored in the cylinder 11 and supplies it to the fuel supply line S. [ Here, the fuel supplied through the fuel supply line S is initially delivered to the high-pressure fuel pump 14 at a low-pressure state, for example, a pressure of about 5 bar.

The high-pressure fuel pump 14 presses a part of the fuel pumped by the fuel pump 12 and supplied through the fuel supply line S at a low pressure to a high pressure, for example, about 40 to 150 bar and supplies it to the delivery pipe 15 , And the remaining fuel is recovered from the internal low-pressure section (30) to the cylinder (11) through the fuel recovery line (R).

On the other hand, at the upstream end of the high-pressure fuel pump 14 of the fuel supply line S and at the downstream end of the high-pressure pump 14 of the fuel recovery line R, And a third pressure sensor (not shown) may be installed in the delivery pipe 15. The pressure sensor (not shown)

Thus, the ECU 17 controls the shutoff valve SV, the fuel pump 12, the multi-valve 13, and the like according to the fuel pressure sensed by the first and second pressure sensors and the third pressure sensor provided on the delivery pipe 15, And the fuel pressure regulator 16 in accordance with the control signal.

Next, the configuration of the high-pressure fuel pump 14 will be described in detail with reference to Figs. 2 to 4. Fig.

FIG. 2 is a perspective view of the high-pressure fuel pump shown in FIG. 1, FIG. 3 is a cross-sectional view of the high-pressure fuel pump taken along line A-A ' Fig.

2 and 3, the high-pressure fuel pump 14 includes a body 20 having a suction port 21 and a discharge port 22 formed on a side surface thereof, a body 20 coupled to a lower portion of the body 20, A bracket 24 provided with a pressurizing means 27 for pressurizing a part of the fuel supplied from the cylinder 11 through a valve 21 and a high pressure valve 27 connected to one side of the body 20 and controlling the supply flow rate of the fuel and the discharge pressure And a spill valve (26).

The high pressure fuel pump 14 is provided between the body 20 and the cam of the engine camshaft (not shown) to convert the rotational motion of the cam into a linear reciprocating motion and transmit it to the pressing means 27, (Not shown) and a damper unit 25 coupled to the upper portion of the body 20 and reducing pulsation of the sucked fuel.

The pressing means 27 serves to generate a suction force and a pressing force of fuel inside the body 20. [

3, the pressure means 27 includes a piston 271 connected to the camshaft of the engine through the roller tappet and moving up and down, and a return spring 274 coupled to the piston 271 to provide a restoring force 272).

The damper unit 25 includes a damper cover 251 and a damper 252. The damper cover 251 is formed in a cylindrical shape having a lower opening to be coupled to the upper portion of the body 20 and a damper 252 ).

A collection port 23 for collecting a part of the fuel supplied to the high-pressure fuel pump 14 to the cylinder 11 may be formed on one side of the damper cover 252, for example, one side or upper surface of the damper cover 252 .

A plurality of troughs 253 may be formed on the outer surface of the damper 252.

The damper unit 25 reduces the pulsation of fuel generated while the fuel is sucked only during the suction operation of the piston 271 provided in the pressurizing unit 27, so that the fuel is stably transported.

When the impact of the pulsation of the fuel on the performance of the high-pressure fuel pump 14 is insignificant, the damper unit 25 is removed when the pulsation of the fuel is small as the magnitude of the fuel pulsation generated in the pumping operation differs according to the specifications of the high- .

As described above, the high-pressure fuel pump 14 according to the preferred embodiment of the present invention has the suction port 21 formed on each side of the body and the recovery port 23 formed in the damper portion 25, The low pressure portion 30 is provided in the low pressure portion 30 and the bomb 11 is provided through the recovery port 23 along the direction of the arrow shown in FIG. 3 before the high pressure of the low pressure fuel filled in the low pressure portion 30, ).

That is, in the present embodiment, the high-pressure fuel pump 14 is provided with the intake port 21 and the recovery port 23 on both sides of the flow control valve 26 and the inlet-side check valve 29, The fuel containing bubbles is immediately recovered to the cylinder 11 while the fuel is vaporized by the generated heat.

Therefore, according to the present invention, the LPF is vaporized by the heat due to the operation of the flow control valve, and the LPF containing bubbles is quickly recovered to the bomb, so that the remaining LPF can be sufficiently pressurized to a preset high pressure to form a high pressure .

Accordingly, the present invention can improve the restartability of the vehicle to which the direct injection type ELF system is applied when the vehicle is restarted after the vehicle is driven at a constant speed.

In addition, according to the present invention, a part of the fuel sucked through the intake port is recovered to the bomb through the damper part and the recovery port, so that the size of the damper part can be minimized or the damper can be removed.

Accordingly, the present invention minimizes the volume of the damper portion, thereby making it possible to manufacture the high-pressure fuel pump compactly, and to reduce the manufacturing cost of the product.

3 and 4, the body 20 is connected to a discharge check valve 28 and a flow control valve 26 which are coupled to the discharge port 22, Side check valve 29 for supplying the fuel to the discharge side check valve 28 while preventing the back flow of the fuel.

A discharge port 211, a suction port 221 and a recovery port 231 may be provided in the suction port 21, the discharge port 22 and the recovery port 23, respectively.

In addition, as shown in FIG. 4, the body 20 is moved in the direction of the movement of the fuel sucked through the suction port 21 toward the inlet-side check valve 29, the pressure means 27 and the discharge port 22 The flow path 201 can be formed.

Next, the coupling relationship and operation method of the high-pressure fuel pump will be described in detail.

First, a piston 271 is installed inside the body 20 after the piston 271 and the return spring 272 are engaged.

The suction port 211 is connected to the suction port 21 formed at one side of the body 20 and the discharge side check valve 28 is provided through the discharge port 22 formed at the other side of the body 20, And the discharge port 221 is coupled to the discharge port 22.

Likewise, the inlet-side check valve 29 is provided through a coupling port formed on one side of the body 20, and then the flow control valve 29 is engaged.

A damper portion 25 is coupled to the upper portion of the body 20 and the recovery port 231 is coupled to the recovery port 23 formed on one side or upper surface of the damper portion 25, Connect the recovery line (R).

When the engine is driven, the assembled high-pressure fuel pump 14 performs the suction, discharge, and recovery operations of the fuel as the piston 271 moves up and down in association with the camshaft.

That is, when the piston 271 is lowered, a suction force is generated in the internal space of the body 20, the fuel is sucked into the internal space of the body 20 through the suction port 23 formed at one side of the body 20, Is transmitted to the pressing means (27) through the moving passage (201) formed inside the body (20).

At this time, the flow control valve 26 opens and closes the inlet-side check valve 29 provided between the damper portion 25 and the pressurizing means 27 to control the fuel supply flow rate and the discharge pressure.

Bubbles may be generated as the fuel filled in the body 20 is vaporized by the heat generated during the operation of the flow control valve 26.

Accordingly, the high-pressure fuel pump 14 according to the present embodiment recovers the fuel containing the bubbles inside the bomb 11 from the low-pressure state via the recovery port 23.

According to the experimental results, the high-pressure pump 14 injects about 95% of the fuel in the idle state of the engine E from the fuel pumped by the fuel pump 12 to the high-pressure pump 14, And recovers about 60% of the fuel to the cylinder 11 during normal operation of the engine E,

The fuel pressure regulator 16 regulates the pressure of the fuel recovered from the low pressure portion 30 of the high pressure pump 14 to the cylinder 11 from the low pressure state 2 bar by the constant pumping operation of the fuel pump 12, When the pressure is increased by, for example,? 5 bar and reaches about 7 bar, the internal valve is opened to transfer the fuel to the cylinder 11.

And, as the fuel pressure regulator 16 is lowered below the above-mentioned 7 bar as the fuel is delivered to the cylinder 11 through the opened valve, when the internal pressure again becomes higher than about 7 bar after closing the valve And repeats the opening operation.

The pressurizing pressure is a pressure preset to prevent vaporization by pressurizing the fuel recovered in the cylinder 11 to achieve thermal equilibrium in the cylinder 11.

Thus, the fuel discharged from the fuel pump 12 and the fuel recovered from the high-pressure pump 14 are thermally balanced within the cylinder 11.

Specifically, in the conventional ELF system, the fuel stored in the cylinder 1 is maintained in a liquid state in the lower portion due to the delivery of the fuel in the cylinder 1, but vaporization occurs in the space above the cylinder, The internal saturated vapor pressure is lowered.

As a result, the internal temperature of the cylinder 1 is drastically lowered, and the fuel is more easily vaporized and cavitation occurs in the primary pumping process, so that the fuel delivery performance of the fuel pump 3 is significantly lowered.

On the other hand, in the present invention, a proper amount of fuel is recovered through the fuel recovery line (R), thereby achieving thermal equilibrium inside the cylinder.

That is, according to the present invention, it is possible to appropriately maintain the level of the liquid fuel in the cylinder by recovering the fuel directly to the cylinder at the low-pressure portion of the high-pressure pump, and to prevent the cavitation in the cylinder by abruptly increasing the void space inside the cylinder .

Particularly, according to the present invention, since the low-pressure fuel is recovered before being supplied to the delivery pipe through the high-pressure pump, the temperature of the fuel can be maintained at a low temperature, and the temperature inside the cylinder can be kept constant.

Accordingly, the inside of the cylinder 11 maintains a thermal equilibrium state. If the thermal equilibrium is established in the cylinder 11 as described above, the pressure feeding process of the fuel can be smoothly performed, and the performance of the LP feed system can be excellently exerted.

Here, the amount of fuel recovered can be controlled to an amount necessary for thermal equilibrium through appropriate evaluation according to the size of the cylinder 11 and the displacement of the vehicle.

On the other hand, as the amount of fuel equal to the amount of fuel injected through the injector I is supplied to the delivery pipe 15 under the high pressure by the high-pressure pump 14, the pressure inside the delivery pipe 15 Is kept constant at the above-mentioned high pressure, i.e., about 40 to 150 bar.

Thus, in the delivery pipe 15 maintained at a high pressure, the vaporization of the fuel is suppressed due to the high pressure, and the LPF supplied to the combustion chamber of the engine E through the injector I is maintained in the liquid state.

Therefore, according to the present invention, a part of the fuel supplied to the high-pressure fuel pump is recovered from the low-pressure portion of the high-pressure fuel pump to the cylinder by the continuous pumping operation of the fuel pump to maintain the thermal balance inside the cylinder, The vaporization of the fuel can be prevented.

Accordingly, it is an object of the present invention to improve the pump efficiency by minimizing the cavitation caused by the vaporization of the LPG fuel during the pressurization and discharge of the fuel, improve the power performance and fuel efficiency of the vehicle by smoothly supplying the fuel, The effect can be obtained.

In addition, since the bubbles contained in the fuel sucked into the body through the inlet-side check valve of the high-pressure fuel pump are quickly recovered to the bomb, the fuel is sufficiently pressurized to a predetermined high pressure It is possible to pressurize.

Accordingly, the present invention can prevent the restart failure due to the bubbles contained in the fuel at the time of restarting the vehicle after the constant-speed running of the vehicle, thereby improving the restartability.

4, the intake port is formed in the body and the recovery port 23 is formed in the damper portion. However, the present invention is not limited thereto.

For example, FIG. 5 is a perspective view showing a modification of the high-pressure fuel pump.

5, the suction port 21 and the recovery port 23 are communicated with each other on both sides of the body 20, and the discharge port 22 is formed on the other side of the body 20 can be changed.

That is, the high-pressure fuel pump 14 is provided with the intake port 21 and the recovery port 23 on both sides of the flow control valve 26 and the inlet-side check valve 29, The fuel containing bubbles is immediately recovered to the cylinder 11.

Therefore, according to the present invention, the LPF is vaporized by the heat due to the operation of the flow control valve, and the LPF containing bubbles is quickly recovered to the bomb, so that the remaining LPF can be sufficiently pressurized to a preset high pressure to form a high pressure .

Accordingly, the present invention can improve the restartability of the vehicle to which the direct injection type ELF system is applied when the vehicle is restarted after the vehicle is driven at a constant speed.

In addition, according to the present invention, a part of the fuel sucked through the intake port is directly recovered to the bomb, and only the remaining fuel is delivered to the damper part, so that the size of the damper part can be minimized or the damper can be removed.

Accordingly, the present invention minimizes the volume of the damper portion, thereby making it possible to manufacture the high-pressure fuel pump compactly, and to reduce the manufacturing cost of the product.

Next, the configuration of the direct injection type ELFI system according to the second embodiment of the present invention will be described in detail with reference to FIG.

FIG. 6 is a configuration diagram of a direct injection type ELISA system according to a second embodiment of the present invention.

As shown in FIG. 6, the direct injection type ELF i system 10 according to the second embodiment of the present invention is similar to that of the first embodiment, except that the fuel injection system And a shut-off valve (19).

The shutoff valve 19 may be provided as a solenoid valve that opens and closes the fuel return line R in accordance with the control signal of the ECU 17. [

In this embodiment, the shutoff valve 19 is installed in the fuel return line R to eliminate the instability in the low temperature or high temperature state according to the temperature change in the engine room and to stably supply the fuel to the injector I And controls to temporarily shut off the fuel for a set time preset after the start of the engine from the start of the engine.

To this end, the ECU 17 generates a control signal for closing the shutoff valve 19 during the set time period when the ignition key is started at the start of the engine.

When the set time has elapsed, the ECU 17 generates a control signal to open the shutoff valve 19 again.

The set time may be set to be longer than a normal vehicle start time.

For example, in the present embodiment, the set time may be set to about 3 to 7 seconds, preferably about 5 seconds.

However, the present invention is not limited thereto, and can be changed and set according to various conditions such as vehicle, engine specifications, performance, and the like.

In addition, the set time may be set within a maximum of 30 seconds in a bad condition in which the temperature inside the engine room suddenly changes due to the influence of climate or the like.

As described above, in the present embodiment, the shutoff valve 19 is closed during the engine starting process to shut off the fuel recovered to the temporary bomb 11, whereby the fuel supply line S is pumped by the pumping operation of the fuel pump 12 Pressure fuel pump 14 to increase the pressure of the fuel supplied to the high-pressure fuel pump 14 to compress the vaporized fuel in the fuel supply line S.

Thus, the high-pressure fuel pump 14 can stably receive the fuel, presses the entire supplied fuel to a predetermined high pressure, and supplies the pressurized fuel to the injector I through the delivery pipe 15.

As described above, according to the present invention, when the engine is started, the shutoff valve is operated to shut off the fuel recovered in the cylinder, and the whole fuel is pressurized to the high pressure and supplied to the injector.

FIGS. 7 and 8 are graphs for evaluating the starting performance of the direct injection type ELPIP system according to the first and second embodiments, respectively.

As shown in Fig. 7, the direct injection type ELFi system 10 according to the first embodiment is configured such that, as the shutoff valve 19 is not used, some of the fuel supplied to the high-pressure fuel pump 14 To the bomb (11).

Accordingly, it can be seen that the startup time of about 1.81 seconds is required as the delay time occurs in the direct injection type ELF system 10 according to the first embodiment to reach the target pressure of the high-pressure fuel portion.

8, the direct injection type ELF i system 10 according to the second embodiment closes the shutoff valve 19 for a predetermined time, for example, about 5 seconds at the time of starting the engine, R).

Thus, the entire fuel supplied to the high-pressure fuel pump 14 is pressurized by the high-pressure fuel pump 14 to a predetermined high pressure, and is supplied to the injector I through the delivery pipe 15.

Accordingly, it can be confirmed that the direct injection type ELiA system 10 according to the second embodiment requires a startup time of about 0.84 seconds by shortening the time required to reach the target pressure of the high-pressure fuel portion.

As described above, the present invention can improve the starting performance of the engine by shortening the time for reaching the target pressure in the high-pressure fuel portion by shutting off the shutoff valve at the time of starting the engine for blocking the fuel recovery.

Further, the present invention reduces the temperature inside the high-pressure fuel pump by opening the shut-off valve after the engine is started and collecting some fuel into the cylinder, thereby smoothly supplying the fuel to the high-pressure fuel portion and the low- .

Although the shutoff valve of the fuel supply line, the shutoff valve of the fuel recovery line, and the fuel pressure regulator are separately provided in this embodiment, the present invention is not limited thereto.

That is, according to the present invention, the shutoff valve provided in the fuel supply line and the fuel pressure regulator provided in the fuel return line are integrally formed in accordance with the shape of the vehicle, the configuration and installation position of the fuel supply system, .

Further, the present invention may be modified to integrally form the shutoff valve, the fuel pressure regulator, and the shutoff valve.

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 relates to a direct injection type air-fuel ratio control system for reducing the time for reaching a target pressure in a high-pressure fuel portion by shutting off a shutoff valve provided in a fuel recovery line for a predetermined time, It applies to the i-system technology.

10: Direct injection type ELISA system 11: Bombardment
12: fuel pump 13: multi-valve
14: High-pressure pump 15: Delivery pipe
16: Fuel pressure regulator 17: ECU
18: motor controller 19: shut-off valve
20: body 201: moving channel
21: Suction port 211: Suction port
22: Discharge port 221: Discharge port
23: collecting port 231: collecting port
24: Bracket 25: Damper portion
251: damper cover 252: damper
253: Goal 26: Flow control valve
27: pressure means 271: piston
272: return spring 28: discharge side check valve
29: inlet side check valve 30: low pressure portion
SV: Shutoff valve S: Fuel supply line
R: fuel return line E: engine
I: Injector

Claims (8)

In a direct injection type LPI system in which liquid state LPG fuel built in a cylinder is directly injected into a combustion chamber of an engine,
A fuel pump which is built in the cylinder and pumps the fuel to the engine,
A high-pressure fuel pump that pressurizes a part of the fuel pumped by the fuel pump and supplied through the fuel supply line to a high pressure and transfers the remaining fuel to the fuel recovery line to recover the fuel to the cylinder,
A shutoff valve installed in the fuel recovery line and opening / closing the fuel recovery line,
And an electronic control unit for controlling the shut-off valve to close the fuel cut-off valve for a predetermined set time so as to block fuel collection through the fuel return line at the time of starting the engine. The method according to claim 1,
A delivery pipe through which the fuel pressurized from the high-pressure fuel pump is filled at a high pressure,
An injector for directly injecting the fuel filled in the delivery pipe into the combustion chamber of the engine,
A motor controller for controlling the driving of the motor in the fuel pump in accordance with the control signal of the electronic control unit,
A shutoff valve installed at a front end of the high-pressure fuel pump of the fuel supply line and closing the fuel supplied from the cylinder by opening and closing operations in response to a drive signal of the motor controller,
Further comprising a fuel pressure regulator provided downstream of the high-pressure fuel pump of the fuel recovery line for reducing the pressure of the fuel recovered from the low-pressure portion of the high-pressure fuel pump to the cylinder,
Wherein the electronic control unit generates a control signal for controlling the driving of the motor and the injector based on the target RPM of the engine. 3. The method of claim 2,
The shutoff valve and the fuel pressure regulator are integrally formed,
Wherein the shut-off valve is installed between the high-pressure fuel pump and the fuel pressure regulator. 3. The method of claim 2,
Wherein the shutoff valve, the fuel pressure regulator, and the shutoff valve are integrally formed. 5. The fuel pump system according to any one of claims 1 to 4, wherein the high-pressure fuel pump
body,
A pressurizing means for pressurizing a part of the fuel supplied from the cylinder through a suction port formed at one side of the body at a high pressure;
And a low pressure portion for transmitting remaining fuel in a low pressure state before being pressurized by the pressurizing portion among the fuel sucked through the inlet port to the fuel returning line,
Wherein the low pressure portion is a path formed inside the body to transmit the low-pressure fuel sucked through the suction port to the fuel recovery line through the recovery port. 6. The apparatus according to claim 5,
A piston provided inside the body and generating a suction force and a pressing force of fuel, a return spring,
A flow control valve coupled to the inlet port for controlling the supply flow rate of the fuel and the discharge pressure,
An inlet-side check valve connected to the flow control valve and
And a discharge-side check valve coupled to a discharge port for discharging the fuel pressurized by the piston. 6. The method of claim 5,
Wherein the high-pressure fuel pump further comprises a damper portion coupled to an upper portion of the body and reducing pulsation of the sucked fuel,
Wherein the intake port and the discharge port for discharging the fuel pressurized by the high pressure to the engine are formed on different sides of the body,
The recovery port is formed on a side surface or an upper surface of the damper portion,
A flow passage for moving fuel sucked into the body is formed between the inlet-side check valve, the damper portion, the pressurizing means, and the discharge-side check valve,
Wherein the damper portion is removable so as to shorten the movement path of the recovered fuel. 6. The method of claim 5,
The suction port and the recovery port communicate with each other at corresponding sides of the body,
And the discharge port for discharging the fuel pressurized by the high pressure to the engine side is formed on the other side of the body.

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