JPH05302550A - Dual fuel automobile - Google Patents

Abstract

PURPOSE:To prevent emission to the atmosphere of residual fuel in one fuel tank and improve the fuel consumption by providing two fuel tanks for storing fuel of different kind, and transferring the residual fuel in the one fuel tank, when fuel therein is decreased to a small amount, to the other fuel tank. CONSTITUTION:In a dual fuel automobile provided with a fuel supply device 28 of including an LNG tank 30 and an LPG tank 32 for individually storing LNG and LPG as the fuel of different kind, the LNG vaporized by a vaporizer 38, after governing the pressure and amount by a regulator 42, is supplied to an internal combustion engine 2 by opening an LNG solenoid valve 36 and closing an LPG solenoid valve 64 at the time of running. Next, an LNG amount in the LNG tank 30 is decreased to a small amount, and when an output from a small quantity detecting sensor 80 is generated, charge/discharge valves 70, 76 are opened by a control part 78 to transfer residual LNG, formed into a high molecular component, to the LPG tank 32 by a pipe 68. Thereafter, the LPG is supplied to the internal combustion engine by closing the LNG solenoid valve 36 and opening the LPG solenoid valve 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual fuel vehicle, and in particular, the residual fuel in one fuel tank is transferred to the other fuel tank to be filled therein, and the composition of new fuel to be filled in one fuel tank is changed at an early stage. The present invention relates to a dual fuel vehicle capable of preventing air pollution, improving fuel efficiency, and preventing air pollution.

[0002]

2. Description of the Related Art Fuels such as gasoline and light oil are mainly used as fuels for internal combustion engines mounted on automobiles.
However, recently, an internal combustion engine that supplies fuel such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas) has been proposed.

That is, as shown in FIGS.
For example, LNG is supplied to 2 as a fuel by the fuel supply device 104. This fuel supply device 104 is
A fuel pipe 114 supplies a fuel from an LNG tank 106, which is a fuel tank for storing G, to a fuel injection valve 110 and a concentration injection valve 112 attached to an intake manifold 108 connected to the internal combustion engine 102. This fuel pipe 114
In addition, the manual extraction valve 116 and the liquefied LNG stored in the LNG tank 106 are sequentially installed from the LNG tank 106 side.
Shutoff valve 118 that is opened and closed to supply and shut off the fuel to the internal combustion engine 102 side, and vaporizer 120 that vaporizes LNG.
And a regulator 12 for adjusting the pressure of the vaporized LNG.
2 and are provided. Vaporizer 120 is LNG
The liquid LNG from the tank 106 side is vaporized. The regulator 122 is connected to the intake manifold 108 by a pressure guiding tube 124 and regulates the pressure of the vaporized LNG.

The fuel injection valve 110 and the enrichment injection valve 11
2. The shutoff valve 118 is connected to the control unit 124.
An air-fuel ratio sensor 126 is also connected to the control unit 124.

A fuel supply device 104 for the internal combustion engine 102.
The shutoff valve 1 supplies the LNG in the LNG tank 106 to the internal combustion engine 102 when the internal combustion engine 102 is operating, in response to signals input from various sensors by the control unit 124.
18 is controlled to open. As a result, the LNG tank 106
LNG flows through the fuel pipe 114, and the vaporizer 12
It is vaporized by 0, regulated and regulated by the regulator 122, supplied to the internal combustion engine 102 by the fuel injection valve 110 or the thickening injection valve 112, and burned. At this time,
The control unit 124 feedback-controls the air-fuel ratio to a target value by the detection signal of the air-fuel ratio sensor 126.

As shown in FIG. 5, a small amount detection sensor 128 for detecting a small amount of LNG is provided in the liquid phase portion at the bottom of the LNG tank 106. The small amount detection sensor 128 is connected to the control unit 124,
The fact that the amount of NG is small is detected as a conduction / non-conduction state of the current due to the float 130 descending and the detection lever 132 coming into contact, and the signal is output to the control unit 124.

A fuel supply device for an internal combustion engine to which fuel other than gasoline and light oil is supplied is disclosed in Japanese Patent Laid-Open No. 1-113529. The fuel supply device described in this publication has a refractive index and a dielectric constant of light of fuel,
A fuel sensor for detecting the mixing ratio of gasoline and methanol, which is the fuel composition, from the electrostatic capacity is provided, and the fuel supply amount to the internal combustion engine and the ignition timing are controlled by the mixing ratio detected by the fuel sensor.

[0008]

By the way, LNG is
The composition changes depending on the sales area and the state of neglect. This change in composition causes a change in the combustion state in the internal combustion engine, which has a disadvantage that the output and the fuel consumption rate are deteriorated and the exhaust gas harmful component value is deteriorated.

Therefore, conventionally, when the amount of LNG in the LNG tank is reduced to about 10% of the capacity of the LNG tank, the residual LNG having a changed composition is released to the atmosphere. This is the residual LNG whose composition has changed in the LNG tank.
This is because, when new LNG is mixed with (ethane, propane, butane), the polymer component is increased and the composition of the new LNG is adversely affected.

However, if the residual LNG is released to the atmosphere in this manner, the LNG cannot be effectively utilized, which causes a problem that fuel consumption is deteriorated and air pollution is caused.

[0011]

In order to eliminate the above-mentioned inconvenience, the present invention provides a fuel supply system with two fuel tanks for respectively storing two kinds of fuel having different properties to be supplied to an internal combustion engine. A residual fuel transfer means for transferring and filling the residual fuel of the one fuel tank to the other fuel tank when the fuel in the one fuel tank becomes small is provided.

[0012]

According to the structure of the present invention, when the amount of fuel in one of the fuel tanks becomes small, the residual fuel in the one of the fuel tanks is transferred to the other of the fuel tanks, and thus the other fuel tank is filled. This residual fuel can be supplied to the internal combustion engine from the other fuel tank without releasing the residual fuel of the other to the atmosphere, improving fuel efficiency and preventing air pollution, and one fuel tank in the empty state. Since the fuel can be filled with new fuel, it is possible to prevent the composition of the new fuel in one of the fuel tanks from changing early.

[0013]

Embodiments of the present invention will now be described in detail and specifically with reference to the drawings. FIG. 1 shows an embodiment of the present invention. In FIG. 1, 2 is an internal combustion engine mounted on an automobile, 4 is a cylinder block, 6 is a cylinder head, 8 is a piston, 10 is a combustion chamber, 12 is an intake manifold, 14 is an intake passage, 16 is a venturi portion, and 18 is Throttle valve, 20 is an intake port, 22 is an intake valve, 24 is an exhaust valve,
26 is an exhaust port.

LNG (liquefied natural gas) and LPG (liquefied petroleum gas) are supplied to the internal combustion engine 2 by the fuel supply device 28 as two kinds of fuel having different properties.

The fuel supply device 28 is provided with an LNG tank 30 for storing LNG as one fuel tank and an LPG tank 32 for storing LPG as the other fuel tank.

The above-mentioned fuels are supplied to the internal combustion engine 2 through a fuel supply pipe 34. This fuel supply pipe 34
Is the liquid phase portion 30 at the bottom of the LNG tank 30 at one end side.
While being located at a, the other end is connected to the intake manifold 12 downstream of the throttle valve 18. This fuel supply pipe 3
4, the LNG solenoid valve 36, the vaporizer 38, and the electromagnetic valve 4 are sequentially arranged from the LNG tank 30 side.
0 and a regulator 42 are provided.

The LNG solenoid valve 36 supplies / shuts off liquefied LNG from the LNG tank 30 to the internal combustion engine 2 side. The vaporizer 38 vaporizes liquefied LNG or LPG fuel. Regulator 42
Is for adjusting the pressure of the vaporized fuel. One end of a pressure introducing pipe 44 is connected to the regulator 42. The other end of the pressure introducing pipe 44 is opened to communicate with the venturi portion 16. Therefore, the operation of the regulator 42 is controlled by the pressure from the pressure introducing pipe 44.

At the upper portion of the LNG tank 30 in the vapor phase portion 30b, one end of a vapor phase LNG introduction pipe 46 is provided. At the other end of the vapor phase LNG introducing pipe 46, the LN
A G adsorption / desorption mechanism 48 is provided. In the gas-phase LNG introduction pipe 46, the pressure gauge 50 is sequentially installed from the LNG tank 30 side.
And an automatic safety valve 52 are provided. The pressure gauge 5
One end of the vapor phase LNG bypass pipe 54 is connected to the midway of the vapor phase LNG introduction pipe 46 between the valve 60 and the automatic safety valve 52.
The other end of the vapor phase LNG bypass pipe 54 is connected to the automatic safety valve 52.
And the LNG adsorption / desorption mechanism 48 are connected in the middle of the gas phase LNG introduction pipe 46. A manual gas release valve (one-way valve) 56 is provided in the middle of the vapor phase LNG bypass pipe 54.

The LNG adsorption / desorption mechanism 48 is provided with a relief valve 58.

Further, one end side of a separated fuel supply pipe 60 is connected to the LNG adsorption / desorption mechanism 48. The other end of the detached fuel supply pipe 60 is connected to the electromagnetic valve 40.

In the liquid phase portion of the LPG tank 32, the LP
One end side of the G supply pipe 62 is provided. The other end of the LPG supply pipe 62 is connected to the fuel supply pipe 34 between the LNG solenoid valve 36 and the vaporizer 38. The LPG tank 32 is provided in the middle of the LPG supply pipe 62.
An LPG solenoid valve 64 for supplying / shutting off the liquefied LPG from is provided.

In the fuel supply device 28, when the amount of fuel in the LNG tank 30, which is one of the fuel tanks, becomes small, for example, about 10% of the capacity of the LNG tank 30, the residual LNG in the LNG tank 30 is left. Residual fuel transfer means 66 is provided to transfer and fill the fuel into the LPG tank 32 which is the other fuel tank.

That is, one end side of the residual fuel supply pipe 68 is provided in the liquid phase portion 30a in the bottom portion of the LNG tank 30. The other end side of the residual fuel supply pipe 68 is provided in the liquid phase portion of the LPG tank 32. In the residual fuel supply pipe 68, sequentially from the LNG tank 30 side,
A first fill and release valve 70, a first coupling 72, a second
A coupling 74 and a second fill and release valve 76 are provided.

The first filling / discharging valve 70 and the second filling / discharging valve 76 are connected to a control unit 78 and can be automatically actuated by the control unit 78 or can be actuated manually. Is.

The control unit 78 includes a small amount detection sensor 80 which outputs an electric signal to that effect to the control unit 78 when the amount of LNG in the LNG tank 30 becomes small at the bottom of the LNG tank 30. Have been contacted.

The control unit 78 is also connected to the LNG solenoid valve 36, the electromagnetic valve 40, and the LPG solenoid valve 64.

LNG stored in the LNG tank 30
In the composition and characteristics of LPG stored in the LPG tank 32, as shown in Table 1, immediately after LNG is filled in the LNG tank 30, methane CH4 evaporates with the passage of time, and finally, LNG containing ethane, propane and normanbutane, which have the same composition as LPG for cold regions
It is clear that it remains as. Therefore, the residual LNG having a changed composition is filled in the LPG tank 32 and mixed with the LPG in the LPG tank 32 to mix the internal combustion engine 2
There is no inconvenience even if it is supplied to.

[Table 1]

Next, the operation of this embodiment will be described.

Before the vehicle travels, first, the LNG tank 30 is fully filled with LNG and the LPG tank 32 is
Fully filled with LPG. At this time, the full filling amount of the LPG tank 32 is set to an amount that can accommodate the residual amount of LNG (about 15% of LNG).

During traveling, the LNG in the LNG tank 30 reaches the vaporizer 38 via the fuel supply pipe 34 by the opening operation of the LNG solenoid valve 36, and is vaporized by the vaporizer 38. At this time, L
The PG solenoid valve 64 is closing. The LNG vaporized by the vaporizer 38 is the regulator 4
The pressure is regulated and adjusted in 2 and is supplied to the internal combustion engine 2 through the intake passage 14.

Further, depending on the operating state of the internal combustion engine 2, the LN
The separated LNG of the G adsorption / desorption mechanism 48 is the separated fuel supply pipe 60.
Is supplied to the electromagnetic valve 40 side from the vaporizer 38, is joined to the vaporized LNG from the vaporizer 38 side, and is supplied to the internal combustion engine 2 side.

By the way, when the amount of LNG in the LNG tank 30 becomes, for example, about 10% of the capacity of the LNG tank 30,
The small amount detection sensor 80 outputs a signal to the control unit 78.

Then, the controller 78 opens the first and second filling / discharging valves 70 and 76, and the residual L which has become a polymer component is left.
NG is transferred from the residual fuel supply pipe 68 into the LPG tank 32. At this time, the internal pressure in the LNG tank 30 is 5〓f / c〓 / 10 ° C for cold regions and 3〓f / c〓 / for summer.
Maximum at 30 ° C. Therefore, since the internal pressure in the LNG tank 30 is 9.5〓f / c〓,
Transfer filling to the PG tank 32 is possible.

Next, the residual LNG in the LNG tank 30
Is completely lost and the LNG tank 30 becomes empty, the first and second filling and discharging valves 70 and 76 are closed.

The residual LNG transferred to the LPG tank 32 is supplied to the internal combustion engine 2 together with the LPG when the LNG solenoid valve 36 closes and the LPG solenoid valve 64 opens. Therefore, the internal combustion engine 2 is operated by the LPG.

As a result, when the amount of LNG in the LNG tank 30 becomes small, the residual LNG whose composition has changed is changed to LPG.
Transfer and fill the tank 32, and after the residual LNG in the LNG tank 30 is completely gone, a new LNG is
The tank 30 can be filled with new LN
It prevents the composition of G from changing early, and also prevents residual LN.
Since G is not released to the atmosphere, it is possible to improve fuel efficiency, prevent air pollution, and eliminate the cause of pollution.

Further, since the components of the residual LNG transferred to the LPG tank 32 are almost the same as those for LPG for cold regions, even if the residual LNG is mixed with LPG and supplied to the internal combustion engine 2, There is no adverse effect on 2.

Further, according to the configuration of this embodiment, the LNG
Although the two types of fuels, LPG and LPG, are supplied to the internal combustion engine 2, parts such as the LPG tank 32 and the residual fuel transfer means 66 are provided on the basis of the conventional LNG fuel supply device of FIGS. Since it is only good, devices such as the vaporizer 38 and the regulator 42 can be commonly used, and the number of parts can be suppressed low.

Furthermore, the LNG and LPG fuels have similar characteristics required by the internal combustion engine 2, such as octane number and fuel speed, so that the LNG characteristics can be fully exhibited. For example, when LNG and gasoline are mixed, the compression ratio can be suppressed to 10 or less.

Furthermore, by sharing the LNG and LPG, it is possible to travel with peace of mind in Japan where such a basic fuel facility is inadequate.

It is needless to say that this embodiment is not limited to the above-mentioned embodiment and various application modifications are possible.

For example, in FIG. 3, according to the result of the fuel evaporation test, if the methane CH4 evaporates over a long period of time, the liquid temperature in the LNG tank 30 suddenly rises (from -130 ° C., for example). -10 ° C). Therefore, as shown in FIG. 2, instead of the small amount detection sensor, the temperature sensor 9
0 is provided in the LNG tank 30, and when the temperature reaches, for example, −100 ° C., a signal is output from the temperature sensor 90 to the control unit 78, and similarly, the operation control of the first and second filling and discharging valves 70 and 76 is performed. Is also possible. As a result, the LPG of the residual LNG can be detected only by detecting the temperature state in the LNG tank 30.
The transfer to the tank 32 can be performed.

When there is a problem in strength due to the design of the LPG tank 32, the safety valve 52 and a manual release valve which is a one-way valve, like the LNG, is introduced into the vapor phase portion in the upper portion of the LPG tank 32. It is also possible to provide the valve 56 and introduce the gas phase LPG to the LNG adsorption / desorption tank 48.

[0044]

As is apparent from the above detailed description, according to the present invention, two fuel tanks for respectively storing two kinds of fuel having different properties to be supplied to the internal combustion engine are provided in the fuel supply device, and one of them is provided. By providing residual fuel transfer means for transferring and filling the residual fuel of one fuel tank to the other fuel tank when the fuel in the fuel tank becomes small, the residual fuel of one fuel tank is released to the atmosphere. Since the residual fuel can be supplied from the other fuel tank to the internal combustion engine without releasing it, the fuel efficiency is improved and the air pollution is prevented, and one empty fuel tank can be filled with new fuel. , It may prevent the composition of the new fuel from changing prematurely.

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a fuel supply device for a dual fuel vehicle.

FIG. 2 is a system configuration diagram of a fuel supply device in which a temperature sensor is provided in the LNG tank.

FIG. 3 is a diagram showing a fuel evaporation test result.

FIG. 4 is a system configuration diagram of a conventional fuel supply device.

5 is a schematic configuration diagram inside the LNG tank in FIG. 4. FIG.

[Explanation of symbols]

 2 Internal Combustion Engine 30 LNG Tank 32 LPG Tank 66 Residual Fuel Transfer Means 70 First Fill Release Valve 76 Second Fill Release Valve 78 Control Unit 80 Small Quantity Detection Sensor

Claims (1)

[Claims] 1. A fuel supply device is provided with two fuel tanks for respectively storing two kinds of fuel having different properties to be supplied to an internal combustion engine, and when one of the fuel tanks has a small amount of fuel, the other fuel tank is provided. A dual fuel vehicle, comprising: a residual fuel transfer means for transferring and filling the residual fuel in the fuel tank in the other fuel tank to the other fuel tank.