KR102277080B1 - Fuel line system for LPDI automobile - Google Patents

Abstract

The present invention relates to a fuel line structure for a LPDI automobile. The fuel line structure comprises: a supply line (20) connected from the fuel pump (12) of a LPG cylinder (10) to an engine (15) via one regulator (21), and for applying pressure to fuel with a high-pressure pump (22) and transmitting the same to a fuel rail (24); a recovery line (30) connected from the high-pressure pump (22) of the supply line (20) to the LPG cylinder (10) via the other regulator (31), and for transmitting non-transmitted fuel in the high-pressure pump (22) to the LPG cylinder (10); and a branch line (40) connected to the other regulator (31) of the recovery line (30), and for inducing pressure reduction due to flow resistance of fuel. Accordingly, the fuel line structure can minimally improve a fuel system associated with the direct injection of liquid LPG fuel in a LPDI vehicle, thereby optimizing fuel control by smoothly supplying fuel according to vehicle driving conditions.

Description

LPDI vehicle fuel line system {Fuel line system for LPDI automobile}

The present invention relates to a fuel line for an LPDI vehicle, and more particularly, to a fuel line system for an LPDI vehicle that directly injects liquid LPG fuel into a cylinder of an engine through an injector.

As interest in eco-friendly, high-efficiency vehicles increases, various alternative fuels are being applied. Among them, LPG fuel has a lower carbon content ratio than gasoline, which is advantageous in reducing carbon dioxide emissions. In the case of vehicles using LPG fuel, electricity is generated from the LPI method to the LPDI (Liquefied Petroleum-gas Direct Injection) method. LPDI vehicles directly inject liquid LPG into the cylinder of the engine through the control of the fuel system. Optimizing fuel control for LPDI vehicles is recognized as an important factor in securing engine performance such as output, fuel efficiency, combustion stability, and startability.

As prior art documents that can be referenced in this regard, Korean Patent Registration No. 0449855 (Prior Document 1), Korean Patent Application Laid-Open No. 2014-0057025 (Prior Document 2), and the like are known.

Prior Document 1 discloses that a fuel auxiliary tank equipped with a compression/expansion member is installed in a vehicle using an LPG liquid injection system to quickly increase the fuel pressure at the rear of the injector, which has fallen to near the internal pressure of the fuel tank, at the same time as the engine is stopped, so that the engine start time shorten the Accordingly, it is expected that the effect of minimizing the inconvenience of the driver due to the instability and time delay of engine start is expected.

Prior Document 2 discloses a regulator that delivers LPG in a fuel tank to a high-pressure fuel pump at a constant pressure; a fuel supply line connecting the fuel tank to the injector to supply LPG to the engine; and a fuel return line installed to return the remaining LPG to the fuel tank. etc. Therefore, it is expected that the hot restart performance and cold start performance of the LPG engine will be improved by applying a regulator capable of variable control.

However, according to the aforementioned prior literature, there is room for improvement in terms of optimization of fuel control while accompanying significant structural changes in the fuel system.

Korean Patent Publication No. 0449855 "A device for improving engine starting performance of an LPG vehicle" (published on: November 5, 2003) Korean Patent Application Laid-Open No. 2014-0057025 "LPG Direct Injection System" (Publication Date: 2014.05.12.)

It is an object of the present invention to improve the conventional problems as described above, to minimize the improvement of the fuel system related to the direct injection of liquid LPG fuel in an LPDI vehicle to maintain smoothness of fuel supply in response to the driving conditions of the vehicle. It is to provide a fuel line system for LPDI vehicles for

In order to achieve the above object, the present invention provides a fuel line system for an LPDI vehicle, comprising: a supply line connected from a fuel pump of an LPG cylinder to an engine through a regulator on one side, boosting fuel with a high-pressure pump and sending it to a fuel rail; a recovery line connected from the high-pressure pump of the supply line to the LPG cylinder through the other side regulator, and sending the undelivered fuel of the high-pressure pump to the LPG cylinder; and a branch line connected to the recovery line in parallel with the regulator and causing pressure reduction due to flow resistance of the fuel.

As a first embodiment of the present invention, a control valve having a flow path switching function is provided on an upstream side that intersects the branch line in the recovery line.

As a second embodiment of the present invention, it is characterized in that a control valve having a flow rate control function is provided at an upstream side that intersects the branch line in the recovery line.

As a detailed configuration of the present invention, the branch line is characterized in that it is provided with a bottleneck member having a reduced flow cross-sectional area.

As a modified example of the present invention, the bottleneck member is characterized in that it further includes an expansion and contraction member for varying the flow cross-sectional area in association with the flow resistance of the fuel.

As described above, according to the present invention, the fuel system related to the direct injection of liquid LPG fuel in the LPDI vehicle is minimized, thereby optimizing fuel control through smooth fuel supply corresponding to the driving conditions of the vehicle. .

1 is a schematic diagram of an LPDI system to which a structure according to the present invention is applied;
2 is a schematic diagram showing a main part of a fuel line according to the present invention;
3 is a schematic diagram showing a modified example of a fuel line according to the present invention;

Hereinafter, an embodiment of the present invention will be described in detail based on the accompanying drawings.

The present invention proposes with respect to a fuel line system of an LPDI vehicle. In the LPDI vehicle, the liquid LPG fuel stored in the LPG cylinder 10 is directly injected into the cylinder of the engine 15 . The present invention is directed to a fuel system of a vehicle equipped with an LPDI engine, but is not necessarily limited thereto.

Referring to FIG. 1 , the fuel system of the LPDI vehicle includes an LPG cylinder 10 , a fuel pump 12 , a high pressure pump 22 , a fuel rail 24 , an injector 26 , and the like. The fuel line is narrowly a conduit for transporting fuel, but broadly includes functional parts mounted on the conduit. A fuel pump 12 is mounted inside the LPG cylinder 10 .

According to the present invention, the supply line 20 connected from the fuel pump 12 of the LPG cylinder 10 to the engine 15 through the one side regulator 21 pressurizes the fuel with the high-pressure pump 22, and the fuel rail 24 ) has a structure that transmits The supply line 20 induces a step-up pressure of the fuel through the fuel pump 12 and the high-pressure pump 22 . The fuel pump 12 supplies fuel of about 8 bar to the high-pressure pump 22 , and the high-pressure pump 22 supplies fuel of about 150 bar to the fuel rail 24 . The pressurized fuel is discharged to the cylinder of the engine 15 through the fuel rail 24 and the injector 26 .

At this time, the regulator 21 of the supply line 20 sends the fuel of the set pressure to the high-pressure pump 22 irrespective of the pressure fluctuation of the LPG cylinder 10 . The regulator 21 may be electrically controlled by the ECU 50 .

In addition, according to the present invention, the recovery line 30 connected from the high-pressure pump 22 of the supply line 20 to the LPG cylinder 10 through the other side regulator 31 removes the fuel not delivered from the high-pressure pump 22 . It has a structure that sends it to the LPG cylinder (10). The high-pressure pump 22 forms a flow path with a suction port, a discharge port, and a recovery port, and includes a spill valve for flow control therein. The undelivered fuel is the remainder not supplied to the fuel rail 24 through the discharge port of the high-pressure pump 22 . The recovery line 30 is connected from the recovery port of the high-pressure pump 22 to the diverter of the LPG cylinder 10 . The fuel pressure of the recovery line 30 is maintained in the range of about 3 to 8 bar.

At this time, the regulator 31 of the recovery line 30 sends the fuel of the set pressure to the LPG cylinder 10 regardless of the pressure fluctuation of the high-pressure pump 22 . The regulator 31 may be electrically controlled by the ECU 50 .

Although the regulators 21 and 31 are shown separately in the present invention, they may be substantially integrally configured.

In addition, according to the present invention, the branch line 40 for causing the pressure reduction due to the flow resistance of the fuel is connected to the recovery line 30 in parallel with the regulator 31 . The branch line 40 forms a flow path bypassed from the upstream side to the downstream side of the regulator 31 . The branch line 40 arranged in parallel with the regulator 31 induces a resistance that interlocks with the flow of fuel. The amount of pressure reduced by the flow path of the regulator 31 or the flow path of the branch line 40 affects the delivery flow rate of the high-pressure pump 22 as will be described later.

As a first embodiment of the present invention, it is characterized in that a control valve 35 having a flow path switching function is provided on an upstream side that intersects the branch line 40 in the recovery line 30 . The control valve 35 having a flow path switching function is driven by a solenoid connected to the ECU 50 . The control valve 35 opens one of the flow path of the regulator 31 and the flow path of the branch line 40 and closes the other.

As a second embodiment of the present invention, a control valve 35 having a flow rate control function is provided on an upstream side where the recovery line 30 intersects with the branch line 40 . The control valve 35 having a flow control function is driven by an actuator connected to the ECU 50 . The control valve (35) fluctuates the opening degree of the flow path of the regulator (31) and the flow path of the branch line (40) at the same time.

Meanwhile, the ECU 50 of the present invention is configured based on a microcomputer circuit and is connected to the fuel pump 12 , the high pressure pump 22 , the regulators 21 and 31 , the injector 26 , and the like. The ECU 50 controls the injection timing and the injection amount of the fuel injected through the injector 26 to a range set according to the driving conditions, respectively.

As a detailed configuration of the present invention, the branch line 40 is characterized in that it is provided with a bottleneck member 42 having a reduced flow cross-sectional area. The bottleneck member 42 is formed of an orifice 44 to perform a function similar to that of the regulator 31 . ΔP pressure-reduced by the bottleneck member 42 is approximately 5 bar, but is not limited thereto. For simplicity of configuration, the bottleneck member 42 may not be directly connected to the ECU 50 .

Referring to FIG. 2 , it shows a state in which the pressure is reduced by an orifice 44 of a throttled form in the middle of the branch line 40 . When a conventional regulator is applied, fuel is supplied and recovered at a set pressure regardless of the driving conditions of the vehicle. In this case, a decrease in fuel supply is caused due to lack of flexibility in fuel recovery in a high-speed or high-torque region where the load of the vehicle is increased.

On the other hand, when the regulator 31 of the recovery line 30 and the bottleneck member 42 of the branch line 40 are connected according to the present invention, smoothness of fuel supply can be maintained by interlocking with the load. The ECU 50 operates the control valve 35 in the set load region to select one function among the regulator 31 and the bottleneck member 42 (first embodiment) or share the functions of both (second embodiment). )do. In the case of the first embodiment, the ECU 50 separates and controls the low load region and the high load region of the engine 15 . In the set low load region, only the flow path of the regulator 31 is opened to perform normal fuel injection of the high pressure pump 22 . Only the flow path of the branch line 40 is opened in the set high load region to cause an increase in fuel pressure and flow rate of the high pressure pump 22 due to a bottleneck caused by the bottleneck member 42 . In the case of the second embodiment, the ECU 50 shares the functions of the regulator 31 and the bottleneck member 42 .

As a modified example of the present invention, the bottleneck member 42 is characterized in that it further includes an expansion and contraction member 46 for varying the flow cross-sectional area in association with the flow resistance of the fuel. Referring to FIG. 3 , it shows a state in which the ring-shaped elastic member 46 is installed in the orifice 44 of the bottleneck member 42 . The stretchable material 46 may vary the flow passage cross-sectional area of the orifice 44 by its own physical properties or external control. For example, the stretchable material 46 is implemented by selecting a stretchable material such as synthetic rubber. When the load variation of the vehicle increases, the elastic material 46 performs a damping function for the fuel system.

The present invention is not limited to the described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Accordingly, it should be said that such variations or modifications fall within the scope of the claims of the present invention.

10: LPG cylinder 12: fuel pump
15: engine 20: supply line
21: regulator 22: high pressure pump
24: fuel rail 26: injector
30: return line 31: regulator
35: control valve 40: branch line
42: bottle neck member 44: orifice
46: elastic material 50: ECU

Claims (5)

In the fuel line system of an LPDI vehicle:
A supply line (20) connected from the fuel pump (12) of the LPG cylinder (10) to the engine (15) through a regulator (21) on one side, boosting the fuel with the high-pressure pump (22) and sending it to the fuel rail (24) ;
A recovery line 30 is connected from the high-pressure pump 22 of the supply line 20 to the LPG cylinder 10 through the other side regulator 31, and sends the undelivered fuel of the high-pressure pump 22 to the LPG cylinder 10. ); and
A branch line 40 connected in parallel with the regulator 31 to the recovery line 30 and causing pressure reduction due to the flow resistance of the fuel;
A control valve 35 having a flow path switching function is provided on an upstream side that intersects the branch line 40 in the recovery line 30, or
A control valve 35 having a flow rate control function is provided on an upstream side that intersects the branch line 40 in the recovery line 30,
The branch line (40) is a fuel line system for an LPDI vehicle, characterized in that it includes a bottleneck member (42) having a reduced flow cross-sectional area. delete delete delete The method according to claim 1,
The bottleneck member (42) is a fuel line system for an LPDI vehicle, characterized in that it further comprises a stretchable material (46) for varying the flow cross-sectional area in association with the flow resistance of the fuel.

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