JP2013130118A - Fuel supply device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply device of an internal combustion engine in which a heat exchanger using heat of an engine cooling water for vaporizing liquified gas fuel is arranged in a fuel tank of the liquified gas fuel, wherein the liquified gas fuel is not mixed into the engine cooling water even though the heat medium passage of the heat exchanger is damaged.SOLUTION: In the fuel supply device of the internal combustion engine in which the first heat exchanger 20 using the heat of the engine cooling water for vaporizing the liquified gas fuel is arranged inside a fuel tank 10 of the liquified fuel, the second heat exchanger 60 is arranged outside of the fuel tank, a heat medium passing through the heat medium passage of the first heat exchanger is heated using the heat of the engine cooling water by the second heat exchanger, and the first heat exchanger indirectly uses the heat of the engine cooling water via the heat medium for vaporizing the liquified fuel.

Description

  The present invention relates to a fuel supply device for an internal combustion engine for vaporizing and supplying liquefied gas fuel to the internal combustion engine.

  As a fuel for an internal combustion engine, it is known to use a gaseous fuel at room temperature and normal pressure such as LPG. Such gas fuel is liquefied by pressurization and cooling and stored in the fuel tank. An internal combustion engine that uses liquid fuel such as gasoline in addition to gas fuel is known, and in such a fuel supply device of the internal combustion engine, in order to reduce the size of the fuel supply device, liquid fuel is liquefied in a fuel tank. It has been proposed to arrange a fuel tank for gas fuel (see Patent Document 1).

  By the way, in a fuel supply device for an internal combustion engine that uses liquefied gas fuel, a heat exchanger for vaporizing the liquefied gas fuel is necessary. To reduce the size of the fuel supply device, a heat exchanger is installed in the fuel tank. It is possible to arrange. Generally, the heat exchanger vaporizes the liquefied gas fuel using the heat of the engine cooling water.

JP2011-052668

  As described above, when the heat exchanger is disposed in the fuel tank of liquefied gas fuel, if the wall of the heat medium passage through which the engine coolant of the heat exchanger passes is damaged, The liquefied gas fuel may be mixed from the liquefied gas fuel passage or from the fuel tank into the engine cooling water passing through the heat medium passage, and the mixed liquefied gas fuel may be vaporized and discharged to the outside from the radiator or the like. .

  Accordingly, an object of the present invention is to provide heat exchange in an internal combustion engine fuel supply apparatus in which a heat exchanger that uses heat of engine cooling water to vaporize liquefied gas fuel is disposed in a fuel tank of liquefied gas fuel. This is to prevent the liquefied gas fuel from being mixed into the engine cooling water even if the heat medium passage of the vessel is damaged.

  According to a first aspect of the present invention, there is provided a fuel supply device for an internal combustion engine, wherein a first heat exchanger that uses heat of engine cooling water to vaporize the liquefied gas fuel is disposed inside the fuel tank of the liquefied gas fuel. In the fuel supply apparatus for an internal combustion engine, a second heat exchanger is disposed outside the fuel tank, and the heat medium passing through the heat medium passage of the first heat exchanger is transmitted by the second heat exchanger. Heated using the heat of the engine cooling water, the first heat exchanger indirectly uses the heat of the engine cooling water through the heat medium to vaporize the liquefied gas fuel. .

  According to a second aspect of the present invention, there is provided the internal combustion engine fuel supply apparatus according to the first aspect, wherein the liquefied gas fuel in the fuel tank is metered into the first heat exchanger. A metering valve for supplying the fuel is disposed inside the fuel tank.

  According to a third aspect of the present invention, there is provided the internal combustion engine fuel supply apparatus according to the first aspect, wherein the liquefied gas fuel in the fuel tank is metered into the first heat exchanger. The metering valve for supplying the fuel is arranged outside the fuel tank.

  According to the fuel supply device for an internal combustion engine of the first aspect of the present invention, the first heat exchanger that uses the heat of the engine cooling water to vaporize the liquefied gas fuel inside the fuel tank of the liquefied gas fuel. The second heat exchanger is disposed outside the fuel tank, and the heat medium passing through the heat medium passage of the first heat exchanger is transmitted to the engine by the second heat exchanger. Heated using the heat of the cooling water, the first heat exchanger indirectly uses the heat of the engine cooling water via a heat medium to vaporize the liquefied gas fuel. Accordingly, in the first heat exchanger inside the fuel tank, the heat medium passage is damaged, and the heat medium in which the liquefied gas fuel passes from the liquefied gas fuel passage of the heat exchanger or from the fuel tank through the heat medium passage. Even if the heat medium is mixed, the heat medium is heated using the heat of the engine cooling water by the second heat exchanger, so that the liquefied gas fuel is not mixed into the engine cooling water.

  According to the fuel supply device for an internal combustion engine according to claim 2 of the present invention, in the fuel supply device for the internal combustion engine according to claim 1, the liquefied gas fuel in the fuel tank is adjusted to the first heat exchanger. Since the metering valve for supplying the metered amount is arranged inside the fuel tank, the upstream pipe and the downstream pipe of the metering valve are located in the fuel tank, and the upstream pipe and the downstream side Even if the piping is damaged, the liquefied gas fuel does not leak out of the fuel tank.

  According to the fuel supply device for an internal combustion engine according to claim 3 of the present invention, in the fuel supply device for the internal combustion engine according to claim 1, the liquefied gas fuel in the fuel tank is adjusted to the first heat exchanger. Since the metering valve for measuring and supplying is arranged outside the fuel tank, the control valve of the metering valve is connected to the fuel tank like when the metering valve is arranged inside the fuel tank. It is not necessary to pull out to the outside, and there is no concern that the liquefied gas fuel leaks from the seal portion at this pulling position.

It is the schematic which shows the fuel tank structure of the fuel supply apparatus of the internal combustion engine by this invention. It is the schematic which shows another fuel tank structure of the fuel supply apparatus of the internal combustion engine by this invention.

  FIG. 1 is a schematic view showing a fuel tank structure of a fuel supply device for an internal combustion engine according to the present invention. In the figure, reference numeral 10 denotes a fuel tank, which stores LPG mainly composed of propane (boiling point −42.09 ° C.) and butane (boiling point −0.5 ° C.). Of course, the liquefied gas fuel targeted by the fuel supply apparatus according to the present invention is not limited to LPG, and can be any combustible substance that is gaseous at normal temperature and pressure. For example, a flammable substance having a boiling point similar to that of propane, a flammable substance having a boiling point comparable to that of butane, and a flammable substance having a boiling point between that of propane and that of butane can be used.

  The liquefied gas fuel F in the fuel tank 10 is vaporized and supplied into the cylinder of the internal combustion engine. For this purpose, a heat exchanger for vaporizing the liquefied gas fuel is required. In the fuel supply apparatus of the present embodiment, a double-pipe heat exchanger 20 is spirally disposed along the inner wall of the fuel tank 10. In this way, a relatively large heat exchanger (long in the case of a double tube heat exchanger) can be disposed in the fuel tank 10 to vaporize a large amount of liquefied gas fuel, and the fuel supply device The whole can be reduced in size.

  If the spiral heat exchanger 20 is brought into contact with the inner wall of the fuel tank 10, the heat exchanger 20 itself functions as a reinforcing member for the fuel tank 10. Since the strength can be increased and the contact area between the heat exchanger 20 and the liquefied gas fuel in the fuel tank 10 is reduced, the liquefied gas fuel stored in the fuel tank 10 is transferred by the heat exchanger 20. It can be made difficult to be heated.

  In addition, the liquefied gas fuel is mainly positioned in the space inside the spiral heat exchanger 20 in the fuel tank 10, and in the spiral double pipe heat exchanger 20, Since both the outer tube and the outer tube can have a relatively large radius of curvature, stress concentration can be reduced. The fuel tank 10 in which the spiral heat exchanger 20 is arranged is preferably cylindrical in accordance with the spiral shape of the heat exchanger 20. In this case, it is preferable that the upper end surface and the lower end surface of the fuel tank 10 have an end plate shape (mirror shape) in order to increase pressure resistance as a pressure vessel.

  The double pipe heat exchanger 20 has a high pressure resistance for both the inner pipe and the outer pipe by using a double pipe having a circular cross section, and the surface area of the wall of the inner pipe that functions as a heat exchange wall is small. It becomes large and high heat exchange efficiency can be realized.

  The inner tube 20a that functions as a liquefied gas fuel passage through which the liquefied gas fuel passes can be made of, for example, aluminum having excellent thermal conductivity, and a heat medium passage through which a heat medium passes outside the inner tube 20a. The outer tube 20b that functions as, for example, can be made of stainless steel having excellent heat insulation. Since the inner tube 20a having a smaller diameter than the outer tube 20b is structurally stronger than the outer tube 20b, the inner tube 20a is preferably used as a passage for liquefied gas fuel having a pressure higher than that of the heat medium.

  Reference numeral 30 denotes a fuel pipe for supplying the liquefied gas fuel in the fuel tank 10 into the inner pipe 20 a of the heat exchanger 20. Most of the fuel pipe 30 is located outside the fuel tank 10, and the lower end face of the fuel tank 10 communicates with the upper end of the inner pipe 20 a of the spiral heat exchanger 20. A metering valve 31 for metering and supplying the liquefied gas fuel into the inner pipe 20a of the heat exchanger 20 is arranged. Further, a closing valve 32 is disposed in the vicinity of the lower end surface of the fuel tank 10 of the fuel pipe 30. The closing valve 32 is normally opened, and the liquefied gas fuel in the fuel tank 10 is pumped into the inner pipe 20a of the heat exchanger 20 through the fuel pipe 30 by the vapor pressure of the liquefied gas fuel in the fuel tank 10. ing. The closing valve 32 is closed as necessary, and the pumping of the liquefied gas fuel in the fuel tank 20 to the heat exchanger 20 can be stopped. A fuel pump may be arranged in the fuel pipe 30 in case the vapor pressure of the liquefied gas fuel in the fuel tank 10 is low.

  On the other hand, 40 is a heat medium pipe for supplying a heat medium into the outer tube 20b of the heat exchanger 20. The heat medium pipe 40 communicates the upper end and the lower end of the outer pipe 20b of the spiral heat exchanger 20, and the heat medium pipe 40 measures the heat medium in the outer pipe 20b of the heat exchanger 20. A metering valve 41 for supplying to is arranged. A heat medium pump 42 for pumping the heat medium is disposed upstream of the metering valve 41. By operating the heat medium pump 42, the heat medium in the heat medium pipe 40 circulates in the outer pipe 20 b and the heat medium pipe 40 of the heat exchanger 20.

  As a result, in the heat exchanger 20, heat is exchanged between the heat medium in the outer tube 20b and the liquefied gas fuel in the inner tube 20a, and the liquefied gas fuel is vaporized, so that the inner tube 20a of the heat exchanger 20 is vaporized. It is discharged from the gas pipe 50 connected to the lower end. In the present embodiment, the heat medium moves the outer tube 20b of the heat exchanger 20 from the upper end toward the lower end. Thereby, the liquefied gas fuel supplied to the upper end of the inner pipe 20a of the heat exchanger 20 can be vaporized satisfactorily by a relatively high-temperature heat medium immediately after flowing into the heat exchanger 20.

  Gas fuel discharged from the gas pipe 50 is supplied to a fuel injection valve (not shown) via a gas fuel tank (not shown) or directly, and is injected from the fuel injection valve to be an internal combustion engine. Is supplied into the cylinder. The gas pipe 50 is provided with a normally open closing valve 51. By closing the closing valve 51 as necessary, the supply of gas fuel to the fuel injection valve can be stopped.

  Further, the upstream side of the closing valve 51 of the gas pipe 50 and the upper end surface of the fuel tank 10 are connected by a relief passage 53 having a safety valve 52, and the gas fuel discharged from the inner pipe 20 a of the heat exchanger 20 is connected. When the pressure becomes excessively high, the safety valve 52 is opened, and the gaseous fuel is returned to the fuel tank 10 via the relief passage 53.

  As described above, the double-pipe heat exchanger 20 has a spiral shape and is not intended to limit the present invention. However, one end of the inner tube 20a and the outer tube 20b is on the upper side, and the other end is on the lower side. It arrange | positions in the fuel tank 10 so that it may become, and liquefied gas fuel is supplied to the inner pipe | tube 20a from the upper end part. Thereby, the liquefied gas fuel is gradually vaporized by receiving heat from the heat medium passing through the outer tube 20b while flowing downward through the spiral inner tube 20a, so that the liquefied gas fuel accumulates in the middle of the inner tube 20a. The liquefied gas fuel can be vaporized satisfactorily.

  By the way, it is preferable that the heat exchanger 20 uses the heat of the engine cooling water so as not to use new energy. However, since the heat exchanger 20 is disposed in the fuel tank 10, the engine cooling water is circulated through the outer pipe 20 b of the heat exchanger 20. When a part of the outer pipe 20b is broken, the vapor pressure of the liquefied gas fuel in the fuel tank 10 may be higher than the circulating pressure of the engine cooling water (for example, 100 kPa). The liquefied gas fuel may be mixed into the engine coolant, vaporize, and discharged from the radiator cap to the outside.

  Further, in the double pipe heat exchanger 20 in the fuel tank 10, if the engine cooling water passes through the inner pipe 20a and the liquefied gas fuel in the outer pipe 20b passes, the outer pipe Even if a part of 20b is broken, the liquefied gas fuel in the outer tube 20b only leaks into the fuel tank 20, and external leakage can be prevented. In this case, when a part of the inner pipe 20a is broken, the liquefied gas fuel in the outer pipe 20b is partially vaporized by heating, and therefore is higher than the circulating pressure of the engine cooling water. The liquefied gas fuel is mixed into the engine cooling water.

  It is necessary to prevent such liquefied gas fuel from being mixed into the engine cooling water. In this embodiment, heat exchange between the heat medium passing through the heat medium pipe 40 and the engine cooling water is already performed. One heat exchanger 60 (second heat exchanger) is disposed outside the fuel tank 10. In another heat exchanger 60, high-temperature engine cooling water before returning from the engine body to the radiator passes around the heat medium pipe 40. As described above, the engine cooling water may be passed through the heat exchanger 60 by using an engine cooling water pump that is generally arranged in the internal combustion engine. A cooling water passage and an electric pump may be provided.

  Thus, the heat exchanger 20 (first heat exchanger) in the fuel tank 10 indirectly uses the heat of the engine coolant through the heat medium to vaporize the liquefied gas fuel. Thereby, even if the heat medium passage is damaged in the heat exchanger 10 in the fuel tank 10, the liquefied gas fuel is not mixed into the engine cooling water circulating in the engine body. The heat medium of the heat exchanger 20 in the fuel tank 10 can be ethylene glycol similar to water or engine cooling water.

  FIG. 2 is a schematic view showing another fuel tank structure of a fuel supply device for an internal combustion engine according to the present invention. Only the differences from FIG. 1 will be described below, and the same members are denoted by the same reference numerals and the description thereof will be omitted. In the present embodiment, the fuel pipe 30 ′ for supplying the liquefied gas fuel in the fuel tank 10 into the inner pipe 20 a of the heat exchanger 20, together with the metering valve 31 ′ and the closing valve 32 ′, Is placed inside.

  Accordingly, even if liquefied gas fuel leaks from the metering valve 31 ′, the closing valve 32 ′, and the fuel pipe 30 ′, the liquefied gas fuel does not leak to the outside of the fuel tank 10. However, a control wiring L from an electronic control device (not shown) for controlling the metering valve 31 ′ and the closing valve 32 ′ must be drawn to the outside of the fuel tank 10 via the seal portion 11. There is a concern that liquefied gas fuel (fuel vapor) may leak from the seal portion 11. In the fuel tank structure shown in FIG. 1, since the metering valve 31 and the closing valve 32 are located outside the fuel tank 10, there is no fear of such fuel leakage.

  In both fuel tank structures shown in FIGS. 1 and 2, the metering valves 31 and 31 ′ for the liquefied gas fuel are used to vaporize the required amount of gas fuel based on the engine operating state. The flow rate of the liquefied gas fuel supplied to the heat exchanger 20 in the tank 10 is controlled. The metering valve 41 for the heat medium supplies the heat medium temperature (measured or estimated) and the heat exchanger 20 so that the pressure of the gas fuel discharged from the gas pipe 50 becomes a desired pressure. The flow rate of the heat medium supplied to the heat exchanger 20 is controlled based on the flow rate of the liquefied gas fuel. Here, the pressure of the gas fuel discharged from the gas pipe 50 is set higher than the pressure of the heat medium circulating in the heat medium pipe 40, and in the heat exchanger 20 in the fuel tank 10, the heat medium passage (for example, outside) When the partition wall (for example, the inner tube 20a) between the tube 20b) and the liquefied gas fuel passage (for example, the inner tube 20a) is damaged, the liquefied gas fuel is mixed into the heat medium. Thereby, when the partition wall (for example, the inner pipe 20a) is damaged, the heat medium is mixed into the liquefied gas fuel and finally supplied into the cylinder, and the engine body is prevented from being damaged.

  Further, if the pressure of the gas fuel discharged from the gas pipe 50 is set higher than the pressure of the heat medium circulating in the heat medium pipe 40, the pressure of the heat medium in the heat medium pipe 40 is measured, When the measured pressure is higher than the set value, in the heat exchanger 20 in the fuel tank 10, the liquefied gas fuel having a pressure higher than that of the heat medium due to damage to the partition wall between the heat medium passage and the liquefied gas fuel passage. It can be determined that is mixed in the heat medium.

DESCRIPTION OF SYMBOLS 10 Fuel tank 20 Heat exchanger 20a Inner pipe 20b Outer pipe 30 Fuel piping 31 Metering valve 40 Heat medium piping 50 Gas piping 60 Heat exchanger

Claims (3)

  A fuel supply device for an internal combustion engine in which a first heat exchanger that uses the heat of engine cooling water to vaporize the liquefied gas fuel is disposed inside the fuel tank of the liquefied gas fuel. A second heat exchanger is disposed, and the heat medium passing through the heat medium passage of the first heat exchanger is heated by the second heat exchanger using heat of engine cooling water, and the first heat exchange The apparatus indirectly uses the heat of the engine cooling water through the heat medium to vaporize the liquefied gas fuel.   2. The internal combustion engine according to claim 1, wherein a metering valve for metering and supplying the liquefied gas fuel in the fuel tank to the first heat exchanger is disposed inside the fuel tank. Engine fuel supply.   2. The internal combustion engine according to claim 1, wherein a metering valve for metering and supplying the liquefied gas fuel in the fuel tank to the first heat exchanger is arranged outside the fuel tank. Engine fuel supply.

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