LPG bombe cooling system of bi-fuel vehicle

An LPG bombe cooling system of a bi-fuel vehicle using both gasoline and LPG is provided. The LPG bombe cooling system is configured to cool the interior of an LPG bombe and to reduce the vapor pressure of LPG by supplying some gasoline from a gasoline tank into the LPG bombe using the fact that the temperature of gasoline in the gasoline tank is lower than the temperature of LPG in the LPG bombe, whereby it is possible to easily refill the LPG bombe with LPG even in the case in which the external temperature is very high, e.g. in the hot season.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of priority to Korean Patent Application No. 10-2016-0088327 filed on Jul. 13, 2016, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to an LPG bombe cooling system of a bi-fuel vehicle.

(b) Background Art

A bi-fuel vehicle using both gasoline and LPG is equipped with a gasoline supply system and an LPG supply system, which are separately provided.

As shown inFIG. 1, a process of filling the LPG bombe of the bi-fuel vehicle with LPG includes a step of operating a filling pump2of an LPG filling station, a step of supplying LPG from an LPG storage space1of the LPG filling station to a filling gun3as the result of operating the filling pump2, and a step of filling the LPG bombe of the vehicle with LPG using an LPG filling pressure of the filling gun3.

The disclosure of this section is to provide background of the invention. Applicant notes that this section may contain information available before this application. However, by providing this section, Applicant does not admit that any information contained in this section constitutes prior art.

SUMMARY

One aspect of the present invention provides an LPG bombe cooling system of a bi-fuel vehicle using both gasoline and LPG, which is capable of cooling the interior of an LPG bombe and reducing the vapor pressure of LPG by supplying some gasoline from a gasoline tank into the LPG bombe using the fact that the temperature of gasoline in the gasoline tank is lower than the temperature of LPG in the LPG bombe, whereby it is possible to easily refill the LPG bombe with LPG even in the case in which the external temperature is very high, e.g. in the hot season.

Another aspect of the present invention provides an LPG bombe cooling system of a bi-fuel vehicle including an auxiliary chamber mounted in an LPG bombe of the bi-fuel vehicle, a first fuel branch line diverging from a gasoline supply line connected between a gasoline tank and an engine and connected to the auxiliary chamber, a second fuel branch line diverging from an LPG supply line connected between an LPI pump mounted in the LPG bombe and the engine and connected to the auxiliary chamber, a first solenoid valve mounted in the first fuel branch line, a second solenoid valve mounted in the second fuel branch line, and a controller for performing control such that the first solenoid valve and the second solenoid valve are opened or closed based on a pressure in the LPG bombe.

In an embodiment, the auxiliary chamber may include a flange portion seated on a mounting hole formed in the LPG bombe, a heat exchange chamber extending from the flange portion into the LPG bombe, and a sealing cover attached to the mounting hole in the LPG bombe on which the flange portion is seated.

In another embodiment, the heat exchange chamber may be provided, at a distal end portion thereof, with a check valve for allowing LPG to flow from the heat exchange chamber into the LPG bombe.

In still another embodiment, the auxiliary chamber may be made of an aluminum material having a high heat transfer rate.

In yet another embodiment, the auxiliary chamber may be provided, at an inlet thereof, with a jet nozzle for spraying gasoline into the heat exchange chamber.

In still yet another embodiment, the first fuel branch line may be provided, at a point thereof between the first solenoid valve and the auxiliary chamber, with a flow meter for measuring an amount of gasoline supplied to the auxiliary chamber.

In a further embodiment, the LPG bombe may have therein a partition wall for partitioning an interior of the LPG bombe into a space in which the auxiliary chamber is disposed and a space in which the LPI pump is disposed and for preventing gasoline from being directly supplied to the LPI pump.

In another further embodiment, the controller may control an amount of time for which the first solenoid valve is open based on a remaining LPG amount measurement signal from an LPG gauge mounted in the LPG bombe in order to determine an amount of gasoline that is supplied to the auxiliary chamber.

In still another further embodiment, when the LPI pump is operated in a state in which the first solenoid valve is closed, the controller may perform control such that the second solenoid valve is open for a predetermined time period, whereby a portion of LPG supplied from the LPG bombe to the engine is supplied to the auxiliary chamber, and at this time the controller may perform control such that the LPI pump is operated at a maximum operating level for a predetermined time period.

In yet another further embodiment, the pressure in the LPG bombe may be measured using a pressure sensor in a regulator mounted in an LPG supply line and an LPG return line.

A further aspect of the invention provides a bi-fuel vehicle comprising: a bi-fuel engine configured to run on two or more fuels which comprises gasoline and LPG (liquefied propane gas or liquefied petroleum gas); a gasoline tank containing gasoline and connected to the engine via a gasoline supply line; an LPG tank containing LPG and connected to the engine via an LPG supply line; a heat exchanger disposed in the LPG tank, the heat exchanger comprising a container which is connected to the gasoline tank via a gasoline branch line which is branched from the gasoline supply line and is further connected to the LPG tank via an LPG branch line which is branched from the LPG supply line, the heat exchanger comprising a check valve; a gasoline valve disposed on the gasoline branch line and configured to control the flow of the gasoline toward the container of the heat exchanger; an LPG valve disposed on the LPG branch line and configured to control the flow of the LPG toward the container of the heat exchanger; and a controller comprising one or more processors and configured to control the gasoline and LPG valves based on the pressure of the LPG tank such that part of the gasoline is transmitted to the container while supplying the gasoline to the engine for combustion, subsequently, either gasoline or LPG is not transmitted to the container for a time period for letting the gasoline in the container to heat-exchange with the LPG contained in the LPG tank; and subsequently, when the LPG is supplied to the engine for combustion, part of the LPG is transmitted to the container in which the part of the LPG is mixed with the gasoline contained in the container, thereby increasing a pressure in the container and causing the mixture of the gasoline and the LPG to be released to the LPG tank through the check valve. Other aspects and embodiments of the invention are discussed infra.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with embodiments, it will be understood that the present description is not intended to limit the invention to those embodiments. On the contrary, the invention is intended to cover not only the embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

A bi-fuel vehicle using both gasoline and LPG is equipped with a gasoline supply system and an LPG supply system, which are separately provided.

In a fuel supply system of the bi-fuel vehicle, in the case where the external temperature is very high, e.g. in the hot season, the pressure in the LPG bombe of the vehicle may be higher than the LPG filling pressure, with the result that LPG filling is not possible.

In the case in which the pressure in the LPG bombe of the vehicle is higher than the LPG filling pressure, a check valve of an excess flow valve mounted in an LPG injection port of the LPG bombe is not opened, with the result that it is not possible to fill the LPG bombe with LPG through the filling gun.

For example, when the atmospheric temperature in the hot season is about 40° C. or higher, the pressure in the LPG bombe of the vehicle becomes higher (e.g. 16.5 bar) than the LPG filling pressure in the filling gun (e.g. 16.3 bar=the pressure in the LPG storage space of the LPG filling station 8.3 bar+the LPG pumping pressure as the result of operating the filling pump 8.0 bar). Consequently, the check valve of the excess flow valve mounted in the LPG injection port of the LPG bombe is not opened, with the result that it may be impossible to fill the LPG bombe with LPG through the filling gun.

Referring toFIG. 2, in embodiments, a gasoline tank10and an LPG bombe or LPG tank20are mounted to the chassis of the bi-fuel vehicle so as to be parallel to each other. In the layout of the bi-fuel vehicle, the distance {circle around (a)} between the LPG bombe20and an exhaust gas discharge line12is shorter than the distance {circle around (b)} between the gasoline tank10and the exhaust gas discharge line12. As a result, the gasoline tank10is less affected by a heat source than the LPG bombe20.

Consequently, the temperature of gasoline in the gasoline tank10is maintained lower than the temperature of LPG in the LPG bombe (which can also be referred as LPG container or LPG tank)20.

In addition, the gasoline supplied from the gasoline tank to an engine is burned without returning to the gasoline tank, whereas the unburned portion of the LPG supplied from the LPG bombe to the engine is returned to the LPG bombe.

Since the LPG is returned from the engine to the LPG bombe in the state in which the temperature of the LPG is increased by the heat of combustion in the engine, the temperature in the LPG bombe is increased.

As a result, the temperature in the LPG bombe becomes higher than the temperature in the gasoline tank. Furthermore, in the case in which the external temperature is very high, e.g. in the hot season, the temperature in the LPG bombe is further increased, and at the same time the pressure in the LPG bombe is also increased. If the pressure in the LPG bombe becomes higher than the LPG filling pressure, it becomes impossible to refill the LPG.

In consideration that the temperature of gasoline in the gasoline tank is lower than the temperature of LPG in the LPG bombe, to reduce the pressure in the LPG tank, some of the gasoline in the gasoline tank is supplied into the LPG bombe to cool the interior of the LPG bombe and to reduce the vapor pressure of LPG using the supplied gasoline.

Hereinafter, the construction of an LPG bombe cooling system of a bi-fuel vehicle according to embodiments of the present invention will be described.

FIG. 3is a view showing the construction of an LPG bombe cooling system of a bi-fuel vehicle according to embodiments of the present invention. InFIG. 3, reference numeral10indicates a gasoline tank for storing gasoline, and reference numeral20indicates an LPG bombe for storing LPG.

The gasoline tank10and the LPG bombe20are connected to a single engine30so as to supply gasoline and LPG to the engine30, respectively.

Specifically, the gasoline tank10is connected to the engine30via a gasoline supply line11, and the LPG bombe20is connected to the engine30via an LPG supply line21.

The LPG bombe20is also connected to the engine30via an LPG return line22. A regulator24having a pressure sensor23is mounted in the LPG supply line21and the LPG return line22.

When LPG from the LPG bombe20is supplied to the engine30via the LPG supply line21and unburned LPG is returned to the LPG bombe20via the LPG return line22, the regulator24controls a flow rate of LPG and senses the pressure of LPG.

Specifically, when LPG from the LPG bombe or LPG tank20is supplied to the engine30via the LPG supply line21, the pressure sensor23, which is included in the regulator24, senses the pressure of LPG passing through the regulator24, and the sensed pressure is transmitted to a controller (ECU)50as a signal indicating the pressure in the LPG bombe20.

According to embodiments of the present invention, the LPG bombe20is provided with an auxiliary chamber40for storing gasoline from the gasoline tank10. Gasoline in the auxiliary chamber40heat-exchanges with the inner space of the LPG bombe and with LPG in the LPG bombe to cool the LPG bombe and LPG in the LPG bombe.

Referring toFIGS. 4 and 5, the auxiliary chamber40includes a flange portion42, which is seated on a mounting hole25formed in the LPG bombe20in a stepped manner, and a heat exchange chamber44, which extends from the flange portion42into the LPG bombe20. The auxiliary chamber40may be preferably made of an aluminum material having a high heat transfer rate.

More preferably, in order to secure sufficient heat exchange area suitable for the internal volume of the LPG bombe20, the heat exchange chamber44may be formed in various shapes, e.g. a straight tube, a zigzag tube, or the like.

In addition, a check valve46is mounted to a distal end portion of the heat exchange chamber44of the auxiliary chamber40in order to allow LPG to flow from the heat exchange chamber44only into the LPG bombe20.

When the auxiliary chamber40is mounted in the LPG bombe20, the heat exchange chamber44is inserted into the LPG bombe20through the mounting hole25in the LPG bombe20such that the flange portion42is seated on the outer periphery of the mounting hole25, a sealing cover48is brought into close contact with the flange portion42, and bolts are fastened from the sealing cover48to the LPG bombe20via the flange portion42.

A first fuel branch line13, which diverges from the gasoline supply line11, passes through the sealing cover48, and the distal end portion of the first fuel branch line13is communicably connected to the auxiliary chamber40.

Specifically, the first fuel branch line13, which diverges from the gasoline supply line11connected between the gasoline tank10and the engine30, passes through the sealing cover48and is communicably connected to the auxiliary chamber40.

The first fuel branch line13is provided with a first solenoid valve14, which is opened or closed in response to a control signal from the controller50, so as to allow or interrupt the flow of gasoline from the gasoline tank10into the auxiliary chamber40.

In addition, a second fuel branch line26diverges from the LPG supply line21connected between an LPI pump27mounted in the LPG bombe20and the engine30, and is also communicably connected to the auxiliary chamber40.

The second fuel branch line26is also provided with a second solenoid valve28, which is opened or closed in response to a control signal from the controller50, so as to allow or interrupt the flow of some of the LPG from the LPG bombe20into the auxiliary chamber40.

As shown inFIG. 6, a jet nozzle45, which is a kind of a jet pump capable of spraying a fixed amount of gasoline from the first fuel branch line26into the heat exchange chamber44in a short amount of time, is mounted to an inlet of the auxiliary chamber40.

As shown inFIG. 7, a flow meter43for measuring the amount of gasoline that is supplied to the auxiliary chamber40and transmitting the measurement result to the controller50is further mounted in the first fuel branch line13connected between the first solenoid valve14and the auxiliary chamber40.

An LPG gauge29for measuring the amount of LPG remaining in the LPG bombe20is mounted in the LPG bombe20, and the remaining amount of LPG measured by the LPG gauge29is transmitted to the controller50as a signal indicating the remaining amount of LPG.

Upon determining that the pressure in the LPG bombe20, which is received from the pressure sensor23, is equal to or higher than a reference pressure, the controller50performs control such that the first solenoid valve14is opened. In addition, the controller50controls the amount of time for which the first solenoid valve14is open based on the amount of LPG remaining in the LPG bombe20, which is received from the LPG gauge29as a signal.

Gasoline from the gasoline tank10passes through the first solenoid valve14, is supplied to the heat exchange chamber44of the auxiliary chamber40, and exchanges heat with the inner space of the LPG bombe and with LPG in the LPG bombe. Consequently, the interior of the LPG bombe is cooled. As a result, the temperature in the LPG bombe is lowered, and the vapor pressure of LPG is also lowered.

The pressure in the LPG bombe20becomes lower than the reference value as the result of the interior of the LPG bombe20being cooled and the vapor pressure of LPG being lowered. Consequently, it is possible to easily refill the LPG bombe20with LPG.

Meanwhile, when the LPI pump27is operated in the state in which the first solenoid valve14is closed, the controller50performs control such that the second solenoid valve28is opened for a predetermined time period, whereby some of the LPG supplied from the LPG bombe20to the engine30is supplied to the heat exchange chamber44of the auxiliary chamber40and is mixed with gasoline.

At this time, the controller50performs control such that the LPI pump27is operated at the maximum operating level for a predetermined time period so that LPG is mixed with gasoline rapidly.

Consequently, LPG is easily mixed with gasoline in the heat exchange chamber44of the auxiliary chamber40, and the pressure in the auxiliary chamber40is increased by pressurization force of the LPI pump, which performs pumping at the maximum operating level. The check valve46mounted to the lower end of the heat exchange chamber44is opened, and gasoline and LPG in the heat exchange chamber44are all discharged into the LPG bombe20.

Therefore, the heat exchange chamber44of the auxiliary chamber40becomes empty. In the state in which the pressure in the LPG bombe does not fall below the reference pressure, the above-described process of filling the auxiliary chamber40with gasoline may be repeatedly performed in order to cool the interior of the LPG bombe.

When gasoline is mixed with LPG, gasoline reduces the vapor pressure of LPG since the temperature of gasoline is lower than the temperature of LPG.

Gasoline and LPG are compounds including C and H (gasoline and LPG are different from each other only in terms of the number of C and H atoms). When gasoline is mixed with LPG, therefore, the mixture is burned without any problem. In order to comply with relevant regulations, however, the controller50may control the amount of time for which the first solenoid value is open such that the amount of gasoline supplied into the auxiliary chamber is less than 10% the amount of LPG.

As shown inFIG. 7, a partition wall18is mounted in the LPG bombe20to partition the interior of the LPG bombe20into a space in which the auxiliary chamber is disposed and a space in which the LPI pump is disposed. The partition wall18prevents gasoline from being directly supplied to the LPI pump.

Hereinafter, the operation of the LPG bombe cooling system according to embodiments of the present invention with the above-stated construction will be described.

FIG. 8is a flowchart showing the operation of the LPG bombe cooling system according to embodiments of the present invention, andFIGS. 9 to 11are views showing the operation of the LPG bombe cooling system according to embodiments of the present invention.

First, the pressure in the LPG bombe20is sensed.

Specifically, the pressure in the LPG bombe20is sensed using the pressure sensor23, and the sensed pressure is transmitted to the controller50as a signal.

Subsequently, the controller50compares the pressure in the LPG bombe20with the upper reference value (e.g. 11 bar) (S101).

When the pressure in the LPG bombe20is lower than the upper reference value (e.g. 11 bar), the controller50performs control such that the first solenoid valve14is closed (S102).

As the result of the first solenoid valve14being closed, gasoline in the gasoline tank10is supplied only to the engine. In embodiments, gasoline in the gasoline tank10is not supplied to the auxiliary chamber40mounted in the LPG bombe20.

When the pressure in the LPG bombe20is higher than the upper reference value (e.g. 11 bar), the controller50performs control such that the first solenoid valve14is opened (S103).

Therefore, as shown inFIG. 9, gasoline from the gasoline tank10is supplied to the engine, and at the same time some gasoline passes through the first solenoid valve14and is supplied to the heat exchange chamber44of the auxiliary chamber40(S104).

Gasoline in the heat exchange chamber44of the auxiliary chamber40exchanges heat with the inner space of the LPG bombe and with LPG in the LPG bombe. Consequently, the interior of the LPG bombe is cooled. As a result, the temperature in the LPG bombe and the temperature of LPG are lowered, and the vapor pressure of LPG is also lowered.

The pressure in the LPG bombe20becomes lower than the reference value (e.g. 11 bar) as the result of the interior of the LPG bombe20being cooled and the vapor pressure of LPG being lowered. Consequently, it is possible to easily refill the LPG bombe20with LPG.

At this time, the controller50compares the amount of time for which the first solenoid valve14is open with a reference time (e.g. the time for which gasoline is supplied into the heat exchange chamber of the auxiliary chamber, about 5 seconds) (S105). Upon determining that the amount of time for which the first solenoid valve14is open exceeds the reference time, the controller50immediately performs control such that the first solenoid valve14is closed (S106).

After the step S106, when LPG in the LPG bombe20is supplied to the engine30by the operation of the LPI pump27, the controller50performs control such that the second solenoid valve28is opened (S107).

Therefore, as shown inFIG. 10, some of the LPG supplied from the LPG bombe20to the engine30is supplied to the heat exchange chamber44of the auxiliary chamber40and is mixed with gasoline.

If LPG supplied to the heat exchange chamber44of the auxiliary chamber40is mixed with gasoline, the vapor pressure of LPG is further reduced by heat exchange with gasoline since the temperature of gasoline is lower than the temperature of LPG. In addition, the temperature in the LPG bombe and the temperature of LPG are further lowered, whereby it becomes possible to easily refill the LPG bombe20with LPG.

At this time, in order to quickly supply LPG to the heat exchange chamber44to be mixed with gasoline, the controller50performs control such that the LPI pump27pumps LPG at the maximum operating level (S108).

Subsequently, the controller50compares the amount of time for which the LPI pump27is operated at the maximum operating level with a reference time (e.g. 10 seconds) (S109). Upon determining that the amount of time for which the LPI pump27is operated at the maximum operating level exceeds the reference time, the controller50performs control such that the operation of the LPI pump27at the maximum operating level is released. This is because the pressure in the LPG bombe has fallen to a value (e.g. 8˜10 bar) lower than the reference pressure.

The pressure generated by the operation of the LPI pump27at the maximum operation level is applied to the heat exchange chamber44of the auxiliary chamber40, in which LPG and gasoline are mixed. Accordingly, the pressure in the heat exchange chamber44is increased higher than the pressure in the LPG bombe20. As a result, the check valve46mounted to the lower end of the heat exchange chamber44is opened.

Therefore, as shown inFIG. 11, both gasoline and LPG in the heat exchange chamber44of the auxiliary chamber40are all discharged into the LPG bombe20via the opened check valve46, and the heat exchange chamber44of the auxiliary chamber40becomes empty.

In the state in which the pressure in the LPG bombe20does not fall below the reference pressure, the above-described process of filling the auxiliary chamber40with gasoline may be repeatedly performed in order to cool the interior of the LPG bombe.

As described above, in the case in which the external temperature is very high, e.g. in the hot season, the interior of the LPG bombe is cooled and the vapor pressure of LPG is lowered using gasoline, the temperature of which is lower than that of LPG. Consequently, it is possible to reduce the pressure in the LPG bombe, making it possible to easily refill the LPG bombe with LPG.

In embodiments, referring toFIGS. 1 to 11, a bi-fuel vehicle includes a bi-fuel engine30, a gasoline tank10, an LPG tank20and a heat exchanger40installed in the LPG tank20. The bi-fuel engine30is capable of runs run on two or more fuels, which are gasoline fuel and LPG (liquefied propane gas or liquefied petroleum gas). The gasoline tank10contains gasoline and is connected to the engine30via a gasoline supply line11, while the LPG tank20contains LPG and is connected to the engine30via an LPG supply line21. The heat exchanger40is disposed in the LPG tank, and includes a container connected to the gasoline tank10via a gasoline branch line13which is branched from the gasoline supply line11. The container is further connected to the LPG tank20via an LPG branch line26which is branched from the LPG supply line21. The heat exchanger40includes a check valve46.

The bi-fuel vehicle further includes a gasoline valve14and an LPG valve28. The gasoline valve14is disposed on the gasoline branch line13and controls the flow of the gasoline fuel toward the container of the heat exchanger40. The LPG valve28is disposed on the LPG branch line26and controls the flow of the LPG toward the container of the heat exchanger40. The vehicle further includes a controller including one or more processors.

The controller50controls the gasoline valve14and the LPG valve28based on the pressure of the LPG tank20. Under the control by the controller50, the gasoline valve14is opened while the LPG valve28is closed such that part of the gasoline fuel is transmitted to the container of the heat exchanger40while supplying the gasoline fuel to the engine30for combustion. Subsequently, the gasoline valve14and the LPG valve28are closed such that either gasoline fuel or LPG is not transmitted to the container for a time period for letting the gasoline fuel contained in the container of the container40to heat-exchange with the LPG contained in the LPG tank20. Subsequently, when the LPG is supplied to the engine30for combustion, the LPG valve28is opened while the gasoline valve14is closed such that part of the LPG is transmitted to the container of the heat exchanger in which the part of the LPG is mixed with the gasoline contained in the container. Supplying the LPG increases the pressure in the container of the heat exchanger40thereby causing the mixture of the gasoline and the LPG in the container of the heat exchanger40to be released to the LPG tank20through the check valve46. In embodiments, the gasoline fuel is not supplied to the heat exchanger40while the LPG is supplied to the heat exchanger40. Further, the LPG is not supplied to the heat exchanger40while the gasoline fuel is supplied to the heat exchanger40.

As is apparent from the above description, embodiments of the present invention have the following effects.

First, it is possible to cool the interior of the LPG bombe, and at the same time to lower the pressure in the LPG bombe by supplying some gasoline from the gasoline tank into the auxiliary chamber in the LPG bombe using the fact that the temperature of gasoline in the gasoline tank is lower than the temperature of LPG in the LPG bombe.

Second, it is possible to lower the vapor pressure of LPG using the cooling effect of gasoline by mixing some gasoline supplied to the auxiliary chamber in the LPG bombe with LPG. As a result, it is possible to further reduce the pressure in the LPG bombe.

In conclusion, in the case in which the external temperature is very high, e.g. in the hot season, the interior of the LPG bombe is cooled and the vapor pressure of LPG is lowered using gasoline, the temperature of which is lower than that of LPG. Consequently, it is possible to reduce the pressure in the LPG bombe, making it possible to easily refill the LPG bombe with LPG.