KR20180065780A - Apparatus for dual fuel switching of two cylinder type and method for supplying fuel - Google Patents

Abstract

Disclosed are a fuel conversion apparatus of a dual cylinder type and a method for supplying fuel. The fuel conversion apparatus of the dual cylinder type according to an embodiment of the present invention comprises: a fuel supply passage connected with an engine; a liquefied gas fuel supply passage connected with the fuel supply passage and a liquefied gas fuel tank; a liquid fuel supply passage connected with the fuel supply passage and a liquid fuel tank; first and second check valves for selectively opening and closing the liquefied gas fuel supply passage and the liquid fuel supply passage; first to sixth solenoid valves for changing a movement route of the liquefied gas fuel supply passage; and a pressure intensifying means for intensifying liquid fuel supplied to the liquid fuel supply passage using pressure of liquefied gas fuel supplied to the liquefied gas fuel supply passage. The pressure intensifying means includes: first and second liquid fuel chambers; first and second pistons for pressurizing the first and second liquid fuel chambers; and first and second liquefied gas fuel chambers in which the first and second pistons reciprocate. Therefore, the fuel conversion apparatus according to the present invention can maintain a constant pressure of fuel at the time of conversion of fuel in a system using fuel of two kinds.

Description

TECHNICAL FIELD [0001] The present invention relates to a two-cylinder type fuel switching device and a fuel supply method,

The present invention relates to a two-cylinder type fuel switching device and a fuel supply method, and more particularly, to a two-cylinder type two-kind fuel switching device And a method of supplying fuel.

A vehicle equipped with a two-kind fuel engine is provided with a fuel supply device for switching the fuel to be supplied to the engine in accordance with the operation of the driver or the control of the control means for diagnosing the condition of the vehicle.

The conventional fuel switching system uses two fuel injection systems and two types of fuel. However, since it requires the use of two fuel systems, not only the system cost increases but also the whole system is unstable.

To improve this, one fuel injection system and a separate fuel switching device or a pressure pump were provided. However, when one fuel injection system and a fuel switching device or a pressurizing pump are used, there is a problem that two fuel are mixed in the fuel tank during the pressurization of the fuel.

In order to solve such a problem, Korean Patent Laid-Open Publication No. 2013-31744 (published on March 29, 2013) discloses a fuel supply apparatus 1 for a two-kind fuel engine as shown in Fig. 1, A fuel supply device 1 for a two-kind fuel engine including a liquid fuel supply passage 203, a liquid fuel supply passage 303, a fuel selection valve 400 and a control unit 500, There is known a technique further including a pressure increase / decrease step for increasing the pressure of the liquid fuel supplied to the flow path 303.

The fuel supply passage 101 is connected to the engine 901, and specifically to the fuel rail. In order to adjust the pressure of the fuel supplied through the fuel supply passage 101 to the required pressure, a pressure adjusting section may be interposed between the fuel rail and the fuel. The fuel that has passed through the pressure adjusting section is supplied to the fuel rail Can be supplied.

The fuel supply passage 101 is connected to the liquefied gas fuel supply passage 203 and the liquid fuel supply passage 303 so as to be supplied with any one selected from the liquefied gas fuel or the liquid fuel.

Next, the liquefied gas fuel supply passage 203 is connected to the liquefied gas fuel tank 201. The liquefied gas fuel tank 201 stores liquefied gas fuel therein, and the stored fuel is supplied to the liquefied gas fuel supply passage 203 at a high pressure by the first pump 202.

Such a system performs a function of increasing the liquid fuel by using the pressure of the liquefied gas fuel when supplying the liquid fuel, and when the predetermined pressure time is to be maintained, it is necessary to increase the fuel pressure chamber to sufficiently pressurize the gasoline, When the pressure piston 620 is retracted, there is a problem that the pressure can not be sufficiently generated and the start-up off phenomenon of the engine may be caused.

2 is a graph showing a change in pressure when the gasoline is pressurized in the fuel supply device 1 of the two-kind fuel engine.

In FIG. 2, the X-axis represents the time and the Y-axis represents the pressure. It can be seen that the section A during which the piston is kept at a constant pressure but rises again after the pressure drops during the retraction of the piston.

The LPG gas contained in the engine fuel system can not be maintained at a high pressure state when the gasoline fuel is switched from the LPG fuel to the LPG fuel. As a result, the LPG gas is evaporated as a result, causing the engine to be shut off.

Korean Patent Application No. 10-2013-0031744

In an embodiment of the present invention, in the fuel switching system of an engine using a two-kind fuel, the LPG fuel in the fuel system is evaporated and filled in the fuel system and the high-pressure pump chamber in a gas state so that sufficient fuel is not supplied to the combustion chamber Cylinder type two-kind fuel switching device and fuel supply device including two cylinders of different phases in order to maintain the fuel pressure sufficiently high and uniform at the time of fuel conversion to solve the problem that the start- And a method thereof.

According to an aspect of the present invention, there is provided a fuel supply system comprising: a fuel supply passage connected to an engine;

A liquefied gas fuel supply passage connected to the fuel supply passage and the liquefied gas fuel tank;

A liquid fuel supply passage connected to the fuel supply passage and the liquid fuel tank;

First and second check valves for selectively opening and closing the liquefied gas fuel supply passage and the liquid fuel supply passage;

Control valves for changing the movement path of the liquefied gas fuel supply passage; And

A pressurized water tank for pressurizing the liquid fuel supplied to the liquid fuel supply passage using the pressure of the liquefied gas fuel supplied to the liquefied gas fuel supply passage;

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Wherein the pressure-

First and second liquid fuel chambers;

First and second pistons for pressing the first and second liquid fuel chambers; And

First and second liquefied gas fuel chambers through which the first and second pistons reciprocate;

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The first and second liquefied gas fuel chambers are disposed in the first space of the first liquefied gas fuel chamber and the second liquefied gas chamber of the first liquefied gas fuel chamber, both of which are partitioned by the first and second pistons to selectively press the first and second pistons. A first liquefied gas fuel branching passage communicating with the second space of the fuel chamber and a second liquefied gas fuel branching passage communicating with the second space of the first liquefied gas fuel chamber and the first space of the second liquefied gas fuel chamber Respectively.

Wherein the first piston comprises:

A first piston portion that pressurizes the first liquid fuel chamber; And

A second piston which pressurizes the first liquefied gas fuel chamber;

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And the second piston includes:

A first piston portion for pressing the second liquid fuel chamber; And

A second piston portion that pressurizes the second liquefied gas fuel chamber;

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The first and second pistons are respectively provided with first and second piston extension bars for supplying liquefied gas fuel to a second space of the first and second liquefied gas fuel chambers, respectively.

The control valves may be first to sixth solenoid valves.

The two-cylinder type two-kind fuel switching device may further include a control unit for controlling opening and closing of the control valves.

The two-cylinder type second fuel switching device may further include a liquefied gas fuel pressure regulator for regulating the pressure of the liquefied gas fuel.

The two-cylinder type second fuel switching device may further include a liquefied gas fuel returning passage through which the liquefied gas fuel pressurized by the first and second pistons returns.

The two-cylinder type second fuel switching device may further include first and second fuel returning passages through which the supplied fuel returns.

The two-cylinder type second fuel switching device may further include a shut-off valve for preventing the liquid fuel from flowing into the second fuel returning passage.

The two-cylinder type second fuel switching device may further include a pressure and temperature sensor for measuring a pressure and a temperature of the fuel supplied to the fuel supply passage.

According to another aspect of the present invention, there is provided a fuel supply method for a two-kind fuel engine by the two-cylinder type two-kind fuel switching device according to claim 1,

A liquid fuel supply step of supplying the liquid fuel to the liquid fuel supply passage and interrupting the supply to the fuel supply passage of the liquefied gas fuel so that the liquefied gas fuel is supplied to the first and second liquefied gas fuel chambers;

The liquid fuel is supplied to the liquid fuel supply passage, and the first liquefied gas fuel branch passage is closed and the second liquefied gas fuel branch passage is opened to allow the liquid fuel filled in the first liquid fuel chamber to flow into the first liquefied gas fuel chamber A first boosting step of causing the first piston to advance and pressurize with pressure and to cause the second piston to retract in the second liquefied gas fuel chamber;

After the first booster step is performed, the first liquefied gas fuel branch passage is opened and the second liquefied gas fuel branch passage is closed, so that the liquid fuel filled in the second liquid fuel chamber is discharged to the pressure of the second liquefied gas fuel chamber A second boosting step for causing the first piston to retract in the first liquefied gas fuel chamber while the two pistons are advanced and pressed; And

(d) repeating the first boosting step and the second boosting step until the liquefied gas fuel remaining in the delivery pipe, the common rail, and the high-pressure pump is combusted in the engine, 2 pressure increasing step;

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A liquefied gas fuel supply step of supplying the liquefied gaseous fuel to the fuel supply passage after the step (d), interrupting the supply of the liquid fuel to the liquid fuel supply passage, and supplying the liquefied gas fuel to the fuel supply passage;

As shown in FIG.

In the first boosting step, the second, third and fifth solenoid valves of the first to sixth solenoid valves may be closed to allow the first piston to advance and pressurize the liquid fuel.

In the second boosting step, the second, fourth and sixth solenoid valves of the first to sixth solenoid valves may be closed to allow the second piston to advance and pressurize the liquid fuel.

According to an embodiment of the present invention, the two-cylinder type fuel switching device and the fuel supplying method include two cylinders having different phases, so that when the LPG to gasoline fuel is switched, two cylinders of the fuel switching device And maintains a constant pressure, so that the start-off phenomenon due to pressure drop can be solved through continuous fuel supply, thereby improving the safety.

1 is a schematic diagram showing a conventional fuel supply system for a two-kind fuel engine.
2 is a graph showing a change in pressure when gasoline is pressurized.
3 is a schematic diagram of a two-cylinder type two-kind fuel switching device according to an embodiment of the present invention.
FIG. 4 is a schematic diagram showing the first piston pressurization in the two-cylinder type two-kind fuel switching device according to the embodiment of the present invention shown in FIG. 3;
FIG. 5 is a schematic view showing a second piston pressurization in the two-cylinder type two-kind fuel switching device according to the embodiment of the present invention shown in FIG.
6 is a graph illustrating a change in pressure when gasoline is pressurized according to an embodiment of the present invention.
7 is a flowchart showing a method of supplying fuel for a two-kind fuel engine according to an embodiment of the present invention.

Various embodiments of the present invention will now be described by way of specific embodiments shown in the accompanying drawings. The differences between the embodiments of the present invention described below are to be understood as mutually exclusive. That is, the specific shapes, structures, and characteristics described may be embodied in other embodiments in accordance with one embodiment without departing from the spirit and scope of the present invention, It is to be understood that the arrangements may be altered, where like reference numerals refer to like or similar features throughout the several views, and length and area, thickness, and the like may be exaggerated for convenience.

FIG. 3 is a schematic diagram of a two-cylinder type fuel switching device according to an embodiment of the present invention. FIG. 4 is a block diagram of a two-cylinder fuel switching device according to an embodiment of the present invention. FIG. 5 is a schematic diagram showing the second piston pressurization in the two-cylinder type fuel switching device according to the embodiment of the present invention shown in FIG. 3; FIG.

3 to 5, the two-cylinder type two-kind fuel switching device includes a fuel supply passage 110, a liquefied gas fuel supply passage 120, a liquid fuel supply passage 130, First to sixth solenoid valves 141 to 146, and a pressure increase / decrease end 150. The first to sixth solenoid valves 141 to 146 and the pressure increase /

The fuel supply passage 110 is connected to the engine.

The liquefied gas fuel supply passage 120 is connected to the fuel supply passage 110 and the liquefied gas fuel tank 112.

The liquid fuel supply passage 130 is connected to the fuel supply passage 110 and the liquid fuel tank 122.

The first and second check valves 131 and 132 are configured to selectively open and close the liquefied gas fuel supply passage 120 and the liquid fuel supply passage 130.

The booster 150 boosts the liquid fuel supplied to the liquid fuel supply passage 130 by using the pressure of the liquefied gas fuel supplied to the liquefied gas fuel supply passage 120.

The booster 150 includes the first and second liquid fuel chambers 151 and 152, the first and second pistons 161 and 162 and the first and second liquefied gas fuel chambers 171 and 172 .

The first piston 161 includes a first piston portion 161a for pressing the first liquid fuel chamber 151 and a second piston portion 161b for pressing the first liquefied gas fuel chamber 171 have.

The second piston 162 comprises a first piston portion 162a for pressing the second liquid fuel chamber 152 and a second piston portion 162b for pressing the second liquefied gas fuel chamber 172 have.

The first and second pistons 161, 162 alternately pressurize the first and second liquid fuel chambers 151, 152.

The first and second pistons 161 and 162 reciprocate between the first and second liquid fuel chambers 151 and 152 and the first and second liquefied gas fuel chambers 171 and 172.

The first and second liquefied gas fuel chambers 171 and 172 are communicated with each other by the first and second liquefied gas fuel branching passages 183 and 184 so as to selectively pressurize the first and second pistons 161 and 162 .

That is, the first liquefied gas fuel branch passage 183 communicates the first space 171a of the first liquefied gas fuel chamber 171 and the second space 172b of the second liquefied gas fuel chamber 172, The second liquefied gas fuel branch passage 184 communicates the second space 171b of the first liquefied gas fuel chamber 171 and the first space 172a of the second liquefied gas fuel chamber 172. [

The first to sixth solenoid valves 141 to 146 are provided to change the movement path of the liquefied gas fuel supply passage 120, respectively.

The two-cylinder type fuel switching device of the present invention further includes a control unit for controlling the opening and closing of the first to sixth solenoid valves 141 to 146.

The control unit closes the second, third, and fifth solenoid valves 142, 143, and 145 of the first to sixth solenoid valves 141 to 146 so that the first piston 161 advances and pressurizes the liquid fuel And the first, fourth, and sixth solenoid valves 141, 144, and 146 are opened.

When the first piston 161 is advanced to the first space 171a of the first liquefied gas fuel chamber 171 to pressurize the liquid fuel, the second piston 162 moves to the second position of the second liquefied gas fuel chamber 172 And retreats into the space 172b.

The first and second pistons 161 and 162 are connected to first and second piston extensions 171 and 172 for supplying liquefied gas fuel to the second spaces 171b and 172b of the first and second liquefied gas fuel chambers 171 and 172, Bars 163 and 164, respectively.

The control unit closes the second, fourth and sixth solenoid valves 142, 144 and 146 of the first to sixth solenoid valves 141 to 146 so that the second piston 162 advances and pressurizes the liquid fuel And the first, third, and fifth solenoid valves 141, 143, and 145 are opened.

When the second piston 162 is advanced to the first space 172a of the second liquefied gas fuel chamber 172 and pressurizes the liquid fuel, the first piston 161 is moved to the second position of the second liquefied gas fuel chamber 172 And retreats into the space 171b.

The two-cylinder type second fuel switching device further includes a liquefied gas fuel pressure regulator 175 for regulating the pressure of the liquefied gas fuel.

The two-cylinder type two-wheel type fuel switching device further comprises a liquefied gas fuel returning passage 177 for returning the liquefied gas fuel pressurized by the first and second pistons 161, 162.

The two-cylinder type two-stage fuel switching device further comprises first and second fuel return passages 181 and 182 through which the supplied fuel returns.

The two-cylinder type second fuel switching device further comprises a shutoff valve 185 for preventing the liquid fuel from flowing into the second fuel return flow path 182.

The two-cylinder type fuel switching device further comprises a pressure and temperature sensor 190 for measuring the pressure and temperature of the fuel supplied to the fuel supply passage 110.

FIG. 6 is a graph showing a change in pressure when gasoline is pressurized according to an embodiment of the present invention.

Referring to FIG. 6, a constant pressure is maintained after being pressurized. In the conventional gasoline pressurization of FIG. 2, when the piston is retracted, the pressure rises again. However, according to the embodiment of the present invention, when the gasoline is pressurized, .

FIG. 7 is a flowchart showing a fuel supply method for a two-kind fuel engine according to an embodiment of the present invention.

Referring to Fig. 7 together with Fig. 3 to Fig. 5, a description will be given of a fuel supply method of the two-cylinder type two-kind fuel switching device. (A) Liquid fuel is supplied to the liquid fuel supply passage, Thereby shutting off the supply of the liquefied gas fuel to the first and second liquefied gas fuel chambers (S110).

(b) supplying the liquid fuel to the liquid fuel supply passage, closing the first liquefied gas fuel branch passage, closing the second, third and fifth solenoid valves, and closing the first, fourth, and sixth solenoid valves The valve is opened and the second liquefied gas fuel branch passage is opened so that the liquid fuel filled in the first liquid fuel chamber is advanced and pressed by the pressure of the first liquefied gas fuel chamber and the second liquefied gas And causes the second piston to retreat within the fuel chamber (S120).

(c) After this process, the first liquefied gas fuel branching passage is opened, the second liquefied gas fuel branching passage is closed, the second, fourth and sixth solenoid valves 142, 144 and 146 are closed, The first, third and fifth solenoid valves (141, 143, 145) are opened so that the liquid fuel filled in the second liquid fuel chamber is advanced and pressed by the pressure of the second liquefied gas fuel chamber Simultaneously, the first piston is retracted in the first liquefied gas fuel chamber (S130).

(d) The first boosting step and the second boosting step are repeated (S140) until the liquefied gas fuel remaining in the delivery pipe, the common rail, and the high-pressure pump is combusted in the engine and the supplied fuel is converted to liquid fuel. When the liquefied gas fuel remains in the delivery pipe, the common rail, and the high-pressure pump, the liquid fuel supply may be interrupted. Therefore, the first boosting step and the second boosting step are repeated until the conversion to liquid fuel becomes 100%.

After step (d), (e) the liquefied gas fuel is supplied to the fuel supply passage, and the supply of the liquefied gas fuel to the fuel supply passage is interrupted by interrupting the supply of the liquid fuel to the liquid fuel supply passage.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Deletion, addition or the like of the present invention may be variously modified and changed within the scope of the present invention.

110: fuel supply passage 112: liquefied gas fuel tank
120: Liquefied gas fuel supply passage 122: Liquid fuel tank
130: Liquid fuel supply passage 131, 132: First and second check valves
141 to 146: First to sixth solenoid valves
150: Stored water
151, 152: first and second liquid fuel chambers
161: first piston 162: second piston
161a, 162a: first piston portion 161b, 162b: second piston portion
171: First liquefied gas fuel chamber
171a: a first space of the first liquefied gas fuel chamber
171b: a second space of the first liquefied gas fuel chamber
172: second liquefied gas fuel chamber
172a: a first space of the second liquefied gas fuel chamber
172b: the second space of the second liquefied gas fuel chamber
175: Liquefied Gas Fuel Pressure Regulator
177: liquefied gas fuel return flow path
181, 182: the first and second fuel return passages
183, 184: First and second liquefied gas fuel branching ducts
185: shutoff valve 190: pressure and temperature sensor

Claims (16)

A fuel supply passage connected to the engine;
A liquefied gas fuel supply passage connected to the fuel supply passage and the liquefied gas fuel tank;
A liquid fuel supply passage connected to the fuel supply passage and the liquid fuel tank;
First and second check valves for selectively opening and closing the liquefied gas fuel supply passage and the liquid fuel supply passage;
Control valves for changing the movement path of the liquefied gas fuel supply passage; And
A pressurized water tank for pressurizing the liquid fuel supplied to the liquid fuel supply passage using the pressure of the liquefied gas fuel supplied to the liquefied gas fuel supply passage;
/ RTI >
Wherein the pressure-
First and second liquid fuel chambers;
First and second pistons for pressing the first and second liquid fuel chambers; And
First and second liquefied gas fuel chambers through which the first and second pistons reciprocate;
Cylinder type two-kind fuel switching device. The method according to claim 1,
The first and second liquefied gas fuel chambers are disposed in the first space of the first liquefied gas fuel chamber and the second liquefied gas chamber of the second liquefied gas fuel chamber, both of which are partitioned by the first and second pistons to selectively press the first and second pistons. A first liquefied gas fuel branching passage communicating with the second space of the fuel chamber and a second liquefied gas fuel branching passage communicating with the second space of the first liquefied gas fuel chamber and the first space of the second liquefied gas fuel chamber Cylinder type two-kind fuel switching device. The method according to claim 1,
Wherein the first piston comprises:
A first piston portion that pressurizes the first liquid fuel chamber; And
A second piston which pressurizes the first liquefied gas fuel chamber;
Cylinder type two-kind fuel switching device. The method according to claim 1,
And the second piston includes:
A first piston portion for pressing the second liquid fuel chamber; And
A second piston portion that pressurizes the second liquefied gas fuel chamber;
Cylinder type two-kind fuel switching device. The method according to claim 1,
Wherein the first and second pistons are respectively provided with first and second piston extension bars for supplying liquefied gas fuel to a second space of the first and second liquefied gas fuel chambers, Fuel conversion device. The method according to claim 1,
Wherein the control valves are first to sixth solenoid valves. The method according to claim 1,
Wherein the two-cylinder type two-kind fuel switching device further comprises a control unit for controlling opening and closing of the control valves. The method according to claim 1,
Wherein the two-cylinder type second fuel switching device further comprises a liquefied gas fuel pressure regulator for regulating the pressure of the liquefied gas fuel. The method according to claim 1,
Wherein the two-cylinder type two-kind fuel switching device further comprises a liquefied gas fuel returning passage through which the liquefied gas fuel pressurized by the first and second pistons is returned. The method according to claim 1,
Wherein the two-cylinder type two-kind fuel switching device further comprises first and second fuel return flow paths through which the supplied fuel returns. The method according to claim 1,
Wherein the two-cylinder type second fuel switching device further comprises a shut-off valve for preventing the liquid fuel from flowing into the second fuel returning passage. The method according to claim 1,
Wherein the two-cylinder type second fuel switching device further comprises a pressure and temperature sensor for measuring a pressure and a temperature of the fuel supplied to the fuel supply passage. A method for supplying a fuel for a two-kind fuel engine by a two-cylinder type fuel switching device according to claim 1,
(a) a liquid fuel supply step of supplying the liquid fuel to the liquid fuel supply passage and cutting off the supply to the fuel supply passage of the liquefied gas fuel, so that the liquefied gas fuel is supplied to the first and second liquefied gas fuel chambers;
(b) supplying the liquid fuel to the liquid fuel supply passage, closing the first liquefied gas fuel branch passage and opening the second liquefied gas fuel branch passage to cause the liquid fuel filled in the first liquid fuel chamber to pass through the first liquefier gas A first boosting step in which the first piston is advanced and pressed by the pressure of the fuel chamber and simultaneously the second piston is retracted in the second liquefied gas fuel chamber;
(c) after the first booster step, the first liquefied gas fuel branch passage is opened and the second liquefied gas fuel branch passage is closed, so that the liquid fuel filled in the second liquid fuel chamber flows into the second liquefied gas fuel chamber A second boosting step of causing the second piston to advance and pressurize with the pressure and at the same time to retreat the first piston in the first liquefied gas fuel chamber; And
(d) repeating the first boosting step and the second boosting step until the liquefied gas fuel remaining in the delivery pipe, the common rail, and the high-pressure pump is combusted in the engine, 2 pressure increasing step;
Fuel ratio of the two-kind fuel engine. 14. The method of claim 13,
After the step (d)
(e) a liquefied gas fuel supply step of supplying the liquefied gas fuel to the fuel supply passage, interrupting the supply of the liquid fuel to the liquid fuel supply passage, and supplying the liquefied gas fuel to the fuel supply passage;
Further comprising the step of: supplying the fuel to the second type of fuel. 14. The method of claim 13,
And the second, third and fifth solenoid valves of the first to sixth solenoid valves are closed to allow the first piston to advance and pressurize the liquid fuel in the first boosting step. Fuel supply method. 14. The method of claim 13,
And the second, fourth and sixth solenoid valves of the first to sixth solenoid valves are closed to allow the second piston to advance and pressurize the liquid fuel in the second boosting step. Fuel supply method.

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