JP2014129811A - Liquid heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently heat fuel of an internal combustion engine.SOLUTION: A fuel heating device 15 is provided in the middle of a fuel passage 13 connected between a fuel injection valve 14 and a fuel pump 12, and the fuel heating device 15 includes: a columnar heating part 16 which heats fuel in the fuel passage 13; and a cylindrical guide part 17 arranged in the surroundings of the heating part 16. The heating part 16 is arranged so as to extend approximately in the horizontal direction in the fuel passage 13, and the guide part 17 is arranged so as to surround the whole circumference of the heating part 16 at predetermined distance from the heating part 16. A plurality of circular through holes 18 are formed on at least each of an upper surface side and a lower surface side of the guide part 17. Thus, when the fuel is heated by the heating part 16, the fuel can be promptly transited to a nucleate boiling state, it becomes possible to maintain the fuel at the nucleate boiling state (or from a later stage of the nucleate boiling state to a former stage of a transition boiling state) for a long time, and the fuel can be efficiently heated.

Description

  The present invention relates to a liquid heating apparatus that heats a liquid in a liquid passage.

In recent years, internal combustion engines that can use gasoline, alcohol (ethanol, methanol, etc.), and alcohol-mixed fuels mixed with gasoline as fuel, in response to social demands such as reducing CO ₂ emissions and using alternative fuels for petroleum. The demand for automobiles equipped with is increasing. However, since alcohol has a larger latent heat of vaporization than gasoline and is difficult to vaporize at low temperatures, the startability of the internal combustion engine is deteriorated when alcohol fuel (100% alcohol or a mixed fuel containing alcohol) is used. There is a problem.

  As a countermeasure against this, there is one that promotes vaporization of the injected fuel by heating the fuel supplied to the fuel injection valve with a heater when the internal combustion engine is at a low temperature. In addition, as a technique for efficiently heating the fuel, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2011-80379), the surface of the heater disposed in the case containing the fuel is roughened. In some cases, air bubbles generated on the surface of the heater when the fuel is heated are easily separated from the surface of the heater.

JP 2011-80379 A

  In the technique of Patent Document 1 described above, the surface of the heater is roughened so that bubbles generated on the surface of the heater when the fuel is heated are easily separated from the surface of the heater. If deposits are generated on the surface of the heater due to the contact of the fuel, the surface state of the heater cannot be maintained at an appropriate rough surface, and the fuel may not be efficiently heated.

  Therefore, the problem to be solved by the present invention is to provide a liquid heating apparatus capable of heating a liquid more reliably and efficiently.

  In order to solve the above problems, the invention according to claim 1 is directed to a liquid heating apparatus in which a heating section (16) for heating a liquid in a liquid passage (13) is disposed in the liquid passage (13). (13) includes a guide portion (17, 24) disposed so as to surround the entire circumference or part of the heating portion (16) at a predetermined distance from the heating portion (16), and the guide portion (17 24), one or a plurality of through holes (18, 20, 21, 22) are formed.

  As shown in FIG. 2, when the liquid is boiled, first, a nucleate boiling state in which relatively small bubbles are generated on the surface of the heating unit is brought about, and then a relatively large bubble (of the heating unit is passed through the transition boiling state). The film transitions to a film boiling state where bubbles are generated to cover the surface. In the nucleate boiling state, the heat transfer coefficient from the heating unit to the liquid increases, and then the heat transfer coefficient decreases in the process of transition from the nucleate boiling state to the film boiling state. Therefore, in order to heat the liquid efficiently, it is preferable to quickly transition the liquid to the nucleate boiling state and to maintain the nucleate boiling state (or from the latter stage of the nucleate boiling state to the first stage of the transition boiling state) for a long time.

  Focusing on this point, in the present invention, since the guide unit is disposed so as to surround the heating unit at a predetermined distance from the heating unit, when heating of the liquid by the heating unit is started, first, the heating unit and the guide are arranged. The liquid in a relatively narrow area between the parts can be heated. Thereby, the temperature of the liquid around a heating part can be raised rapidly, and a liquid can be changed to a nucleate boiling state rapidly.

  In addition, since the through hole is formed in the guide portion, bubbles generated by nucleate boiling are cooled and disappeared by being discharged to the outside of the guide portion through the through hole. In the nucleate boiling state, the generation and disappearance of such bubbles cause a turbulence (flow) of the liquid around the heating unit, and the heat transfer rate from the heating unit to the liquid is improved.

  Furthermore, the bubbles generated by nucleate boiling are discharged to the outside of the guide part through the through-hole, thereby suppressing the bubbles from gathering around the heating part to form large bubbles, and to the film boiling state. Transition can be suppressed, and the nucleate boiling state (or the late stage of the nucleate boiling state to the early stage of the transition boiling state) can be maintained for a long time.

  In this way, the liquid can be quickly transitioned to the nucleate boiling state, and can be maintained in the nucleate boiling state (or from the latter stage of the nucleate boiling state to the first stage of the transition boiling state) for more reliable liquid Can be efficiently heated.

FIG. 1 is a diagram showing a schematic configuration of a fuel supply system according to Embodiment 1 of the present invention. FIG. 2 is a diagram for explaining a nucleate boiling state, a transition boiling state, and a film boiling state. FIG. 3 is a partially broken side view of the fuel heating device in a nucleate boiling state. FIG. 4 is a diagram for explaining the effect of the first embodiment. FIG. 5 is a partially broken side view of the fuel heating apparatus according to the second embodiment. FIG. 6 is a plan view of the fuel heating apparatus according to the second embodiment. FIG. 7 is a partially broken side view of the fuel heating apparatus according to the third embodiment. FIG. 8 is a partially broken side view of the fuel heating apparatus according to the fourth embodiment. FIG. 9 is an external perspective view of the fuel heating rail of the fifth embodiment. FIG. 10 is a front sectional view of the fuel heating rail of the fifth embodiment. FIG. 11 is a side sectional view of the fuel heating rail of the fifth embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, a schematic configuration of an engine fuel supply system will be described with reference to FIG.

  An engine (not shown) that is an internal combustion engine can use any of gasoline, alcohol (such as ethanol and methanol), and alcohol-mixed fuel obtained by mixing alcohol with gasoline as fuel (liquid). One of these gasoline, alcohol, and alcohol mixed fuel is supplied to the fuel tank 11 and supplied to the engine. A fuel tank 12 that pumps fuel is installed in a fuel tank 11 that stores fuel. The fuel discharged (pressure-fed) from the fuel pump 12 is supplied to the fuel injection valve 14 through the fuel passage 13 (liquid passage).

  In the middle of the fuel passage 13 connected between the fuel injection valve 14 and the fuel pump 12, a fuel heating device 15 (liquid heating device) is provided. The fuel heating device 15 is provided with a columnar heating unit 16 (for example, an electric heater) that heats the fuel in the fuel passage 13 and a cylindrical guide unit 17 disposed around the heating unit 16. It has been.

  The heating unit 16 is disposed so as to extend substantially horizontally in the fuel passage 13, and the guide unit 17 is disposed so as to surround the entire circumference of the heating unit 16 at a predetermined distance from the heating unit 16. A plurality of circular through holes 18 are formed at least on the upper surface side and the lower surface side of the guide portion 17. Fuel heated by the heating unit 16 and bubbles generated by boiling are discharged to the outside of the guide unit 17 through the through hole 18 on the upper surface side of the guide unit 16 and guided from the through hole 18 on the lower surface side of the guide unit 16. The fuel flows into the portion 17.

  The ECU 19 (control means) is composed mainly of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby control the fuel injection amount and the engine operation state. Control ignition timing. In addition, when the fuel is heated by the heating unit 16, the ECU 19 controls the heating unit 16 so that the surface temperature of the heating unit 16 is higher than the boiling point of the fuel.

  The ECU 19 may be configured by a single control circuit that comprehensively controls the engine (fuel injection amount, ignition timing, etc.), the fuel pump 11, the heating unit 16, and the like, or a control circuit that controls the engine; A control circuit that controls the fuel pump 11 and a control circuit that controls the heating unit 16 may be provided separately.

  As shown in FIG. 2, when the fuel boils, first, a nucleate boiling state in which relatively small bubbles are generated on the surface of the heating unit 16 is obtained, and then relatively large bubbles (heating unit) are passed through the transition boiling state. Transition to a film boiling state in which bubbles 16 covering the surface of 16 are generated. In the nucleate boiling state, the heat transfer rate from the heating unit 16 to the fuel increases, and then the heat transfer rate decreases in the process of transition from the nucleate boiling state to the film boiling state. Therefore, in order to heat the fuel efficiently, it is preferable to quickly change the fuel to the nucleate boiling state and to maintain it for a long time from the nucleate boiling state (or from the latter stage of the nucleate boiling state to the first stage of the transition boiling state).

  Focusing on this point, in this embodiment, since the guide portion 17 is disposed so as to surround the heating portion 16 at a predetermined distance from the heating portion 16, when heating of the fuel by the heating portion 16 is started, The fuel in a relatively narrow region between the heating unit 16 and the guide unit 17 can be heated. Thereby, the temperature of the fuel around the heating unit 16 can be quickly raised, and the fuel can be quickly changed to the nucleate boiling state.

  In addition, since the through hole 18 is formed in the guide portion 17, bubbles generated by nucleate boiling are cooled and disappeared by being discharged to the outside of the guide portion 17 through the through hole 18. As shown in FIG. 3, in the nucleate boiling state, the turbulence (flow) of the fuel occurs around the heating unit 16 due to the generation and disappearance of such bubbles, and the heat transfer rate from the heating unit 16 to the fuel is improved. .

  Further, the bubbles generated by the nucleate boiling are discharged to the outside of the guide portion 17 through the through-holes 18, thereby suppressing the bubbles from gathering around the heating portion 16 to become large bubbles, and the film Transition to the boiling state can be suppressed, and the nucleate boiling state (or the latter stage of the transition boiling state from the latter stage of the nucleate boiling state) can be maintained for a long time.

  In the first embodiment described above, the guide portion 17 is disposed so as to surround the heating portion 16 at a predetermined distance from the heating portion 16, and the through hole 18 for discharging bubbles is formed in the guide portion 17. As described above, when the fuel is heated by the heating unit 16, the fuel can be quickly changed to the nucleate boiling state, and the nucleate boiling state (or from the latter stage of the nucleate boiling state to the first stage of the transition boiling state) is prolonged. The fuel can be maintained, and the fuel can be heated more reliably and efficiently. Moreover, in the first embodiment, the surface temperature of the heating unit 16 is controlled to a temperature higher than the boiling point of the fuel. Therefore, the fuel around the heating unit 16 is quickly heated to a temperature higher than the boiling point to Can be boiled.

  As a result, as shown in FIG. 4, the fuel heating device 15 of the first embodiment can heat the fuel more efficiently than the conventional fuel heating device (fuel heating device that does not include a guide portion). The temperature of the fuel can be quickly raised.

  Embodiments 2 to 5 according to the present invention will be described below with reference to FIGS. However, parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted or simplified, and parts different from those in the first embodiment are mainly described.

  As shown in FIGS. 5 and 6, in the second embodiment, a plurality of types of through holes 20 to 22 are formed in the guide portion 17. Specifically, a large-diameter circular through hole 20 is formed in the center portion on the upper surface side of the guide portion 17 (the portion corresponding to the center portion of the heating portion 16), and the center on the upper surface side of the guide portion 17. An elliptical through hole 21 having an opening area smaller than that of the central through hole 20 is formed in a part other than the part (a part corresponding to the tip side and the base side of the heating part 16). When the amount of heat generated in the central part of the heating unit 16 is large, many bubbles are generated near the central part on the upper surface side of the heating unit 16, so the through hole 20 in the central part on the upper surface side of the guide unit 17 is enlarged. Thus, bubbles generated near the central portion on the upper surface side of the heating unit 16 can be easily discharged from the large through-hole 20 in the central portion on the upper surface side of the guide portion 17.

  On the other hand, a small-diameter circular through hole 22 having a smaller open area than the through holes 20 and 21 on the upper surface side is formed on the lower surface side of the guide portion 17, and the number of the through holes 22 on the lower surface side is set to the upper surface. The number is smaller than the number of through holes 20 and 21 on the side. Accordingly, it is possible to suppress a large amount of fuel that is not heated from the through hole 22 on the lower surface side of the guide portion 17 from flowing into the periphery of the heating portion 16 and to reduce the temperature of the fuel around the heating portion 16. By suppressing it, the ease of discharging bubbles is increased.

  As shown in FIG. 7, in the third embodiment, a chamfer 23 is formed on the opening peripheral edge of the lower side (heating unit 16 side) of the through hole 18 on the upper surface side of the guide unit 17. Thus, fuel and bubbles are easily discharged from the through hole 18 on the upper surface side of the guide portion 17. Further, a chamfer 23 is formed on the opening peripheral portion of the lower side of the guide portion 17 below the through hole 18 (opposite the heating portion 16). As a result, the fuel can easily flow from the through hole 18 on the lower surface side of the guide portion 17.

  In the first to third embodiments, the cylindrical guide portion 17 is used. However, the shape of the guide portion is not limited to the cylindrical shape, and may be changed as appropriate. A polygonal cylindrical guide portion such as the above may be used.

  As shown in FIG. 8, in the fourth embodiment, a semi-cylindrical guide portion 24 is disposed so as to surround the upper surface side of the heating portion 16. Since the fuel heated by the heating unit 16 is directed upward by natural convection, even if the semi-cylindrical guide unit 24 surrounds only the upper surface side of the heating unit 16, the same effect as in the first embodiment can be obtained. (The fuel can be promptly transitioned to the nucleate boiling state and can be maintained for a long time in the nucleate boiling state (or from the latter stage of the nucleate boiling state to the first stage of the transition boiling state)).

  In the fourth embodiment, the semi-cylindrical guide portion 24 is used. However, the shape of the guide portion is not limited to the semi-cylindrical shape, and may be changed as appropriate. The upper surface side of the heating unit 16 may be surrounded by a guide portion having a shape or a guide portion having a U-shaped cross section.

Next, Embodiment 5 of the present invention will be described with reference to FIGS.
As shown in FIG. 9, the fuel discharged from the fuel pump 12 (see FIG. 1) is sent to a fuel heating rail 26 (liquid heating device) through a fuel pipe 25 from the fuel heating rail 26 to each cylinder of the engine. Fuel is supplied to the attached fuel injection valve 14. The fuel heating rail 26 includes a fuel rail 27 (liquid rail) connected to the fuel pipe 25 and a plurality of fuel heating chambers attached to the fuel rail 27 at positions corresponding to the fuel injection valves 14 of each cylinder. 28 (liquid heating chamber). The fuel rail 27 and the fuel heating chamber 28 function as a fuel passage (liquid passage), and the fuel sent into the fuel rail 27 through the fuel pipe 25 is supplied to the fuel injection valve 14 of each cylinder through each fuel heating chamber 28. Is done.

  As shown in FIGS. 10 and 11, the fuel rail 27 is formed by attaching an upper lid 30 to a lower lid 29, and a fuel passage is formed between the lower lid 29 and the upper lid 30. A box-shaped fuel heating chamber 28 is attached to the upper lid 30 of the fuel rail 27.

  As shown in FIG. 10, the fuel heating chamber 28 has a substantially cylindrical attachment portion 31 for attaching the heating portion 16 to the fuel heating chamber 28 in the lateral direction (a direction substantially parallel to the upper surface of the fuel rail 27). It attaches so that it may extend, and the guide part 17 is connected to the front end side of this attaching part 31. In the fifth embodiment, the attachment portion 31 and the guide portion 17 are formed as an integral part. The guide portion 17 is not limited to the guide portion described in the first embodiment, and may be the guide portion described in any of the second to fourth embodiments.

  Further, a support fixing portion 32 having a larger diameter than the heating portion 16 is integrally provided on the base side of the heating portion 16. The heating unit 16 is inserted from the side of the fuel heating chamber 28 to the inside of the guide unit 17 through the inside of the mounting unit 31 and the support fixing unit 32 is assembled and fixed to the mounting unit 31. Is inserted from the side of the fuel heating chamber 28 and attached in a state extending in the lateral direction.

  An inflow pipe 33 for introducing the fuel in the fuel rail 27 into the fuel heating chamber 28 is provided on the front end side of the heating unit 16 in the fuel heating chamber 28. An inflow port 34 is provided. On the other hand, a discharge pipe 35 for discharging the fuel in the fuel heating chamber 28 (supplying it to the fuel injection valve 14 side) is provided on the base side of the heating unit 16 in the fuel heating chamber 28. A fuel discharge port 36 is provided at the tip of 35. In other words, the fuel inlet 34 is disposed on the leading end side of the heating unit 16 in the fuel heating chamber 28, and the fuel discharge port 36 is disposed on the root side of the heating unit 16 in the fuel heating chamber 28.

  As shown in FIG. 11, the fuel inflow port 34 and the discharge port 36 are arranged behind the heating unit 16 (leftward in FIG. 11), and a partition wall 37 is provided between the inflow port 34 and the discharge port 36. Is arranged. The partition wall 37 is provided behind the heating unit 16 so as to partition the inlet 34 side and the outlet 36 side. As a result, the fuel that has flowed into the fuel heating chamber 28 from the inlet 34 flows in the direction substantially along the longitudinal direction of the heating unit 16 from the distal end side to the root side of the heating unit 16, and then from the discharge port 36. The fuel is discharged outside the fuel heating chamber 28.

  In the fifth embodiment described above, the fuel heating chamber 28 is configured by attaching the fuel heating chamber 28 to the upper lid 30 of the fuel rail 27, so that the fuel projected on the fuel heating rail 26 can be increased without substantially increasing the projected area. The heating chamber 28 can be attached (the fuel heating chamber 28 can be accommodated within the upper projected area of the fuel rail 27). Further, since the heating unit 16 is inserted into the fuel heating chamber 28 from the side of the fuel heating chamber 28 and extends in the lateral direction, the fuel heating performance of the fuel by the heating unit 16 is ensured while ensuring the fuel heating performance. The height dimension of the heating chamber 28 can be kept low, and the height dimension of the entire fuel heating rail 26 can be kept low. Thereby, the mounting property to the vehicle of the fuel heating rail 26 can be improved.

  Further, in the fifth embodiment, since the attachment portion 31 and the guide portion 17 are formed as an integral part, the fuel heating rail 26 of the fuel heating rail 26 is compared with the case where the attachment portion 31 and the guide portion 17 are separate parts. The number of parts can be reduced and the assemblability (productivity) can be improved, and the fuel heating rail 26 can be reduced in cost.

  Further, in the fifth embodiment, a fuel inflow port 34 is disposed on the front end side of the heating unit 16 in the fuel heating chamber 28, and a fuel discharge port is provided on the base side of the heating unit 16 in the fuel heating chamber 28. Since 36 is arranged, the fuel in the fuel heating chamber 28 can flow from the front end side of the heating unit 16 toward the root side. Thereby, the fuel in the fuel heating chamber 28 can be made to flow in a direction substantially along the longitudinal direction of the heating unit 16, and the fuel in the fuel heating chamber 28 can be efficiently heated by the heating unit 16.

  In the fifth embodiment, a fuel inflow port 34 is disposed on the leading end side of the heating unit 16 in the fuel heating chamber 28, and a fuel discharge port is provided on the base side of the heating unit 16 in the fuel heating chamber 28. However, the present invention is not limited to this, and a fuel inflow port 34 is arranged on the base side of the heating unit 16 in the fuel heating chamber 28, and the heating unit 16 in the fuel heating chamber 28 is arranged. A fuel discharge port 36 may be disposed on the front end side.

  Moreover, in the said Example 5, although the attachment part 31 and the guide part 17 were formed with integral components, it is not limited to this, As the attachment part 31 and the guide part 17 are formed with another components, Also good.

  Moreover, in each said Examples 1-5, it was made to use the cylindrical heating part 16, However, The shape of a heating part is not limited to a cylindrical shape, You may change suitably, for example, a square pole, A prismatic heating unit such as a hexagonal column or a flat heating unit may be used. Furthermore, you may make it arrange | position so that a some heating part may mutually serve as a guide part, or one may serve as the other guide part.

  Further, in each of the first to fifth embodiments, a circular (or elliptical) through hole is formed in the guide portion. However, the shape of the through hole is not limited to this, and may be changed as appropriate. For example, a polygonal through hole such as a quadrangle, an elliptical through hole, or a mesh-like through hole may be formed. Further, the guide portion may be configured by combining a plurality of members, and a gap formed between the plurality of members may be used as a through hole.

  Furthermore, the number and position of through holes formed in the guide may be changed as appropriate. In each of the first to fifth embodiments, a plurality of through holes are formed in the guide portion. However, a single through hole may be formed in the guide portion.

  In addition, the present invention is not limited to the fuel heating device that heats the fuel of the internal combustion engine, and the present invention may be applied to a liquid heating device that heats other liquids such as cooling water and lubricating oil of the internal combustion engine. Further, the present invention is not limited to the internal combustion engine, and the present invention may be applied to a liquid heating apparatus in a field other than the internal combustion engine, such as a liquid heating apparatus for a hot water washing toilet seat or a food heating sterilization.

  DESCRIPTION OF SYMBOLS 12 ... Fuel pump, 13 ... Fuel passage (liquid passage), 14 ... Fuel injection valve, 15 ... Fuel heating device (liquid heating device), 16 ... Heating part, 17 ... Guide part, 18 ... Through-hole, 19 ... ECU ( Control means) 20-22 ... through hole, 24 ... guide portion, 27 ... fuel rail (liquid rail), 28 ... fuel heating chamber (liquid heating chamber)

Claims (6)

In the liquid heating apparatus in which the heating section (16) for heating the liquid in the liquid passage (13, 28) is disposed in the liquid passage (13, 28),
Guide portions (17, 24) arranged to surround the entire circumference or a part of the heating portion (16) at a predetermined distance from the heating portion (16) in the liquid passage (13, 28). The liquid heating apparatus is characterized in that one or a plurality of through holes (18, 20, 21, 22) are formed in the guide portion (17, 24). The liquid is a fuel for an internal combustion engine;
The liquid passage is a fuel passage (13, 28) connected between a fuel injection valve (14) of the internal combustion engine and a fuel pump (12) for pumping the fuel to the fuel injection valve (14). The liquid heating apparatus according to claim 1.   3. The liquid heating apparatus according to claim 1, further comprising a control unit that controls a surface temperature of the heating unit to be higher than a boiling point of the liquid. 4. The liquid passage includes a liquid rail (27) having a lower lid (29) and an upper lid (30), and a liquid heating chamber (28) attached to the upper lid (30) of the liquid rail (27),
The said liquid heating chamber (28) has the said heating part (16) inserted from the side of the said liquid heating chamber (28), and is attached in the state extended in the horizontal direction. 4. The liquid heating apparatus according to any one of 3.   The attachment part (31) for attaching the said heating part (16) to the said liquid heating chamber (28) and the said guide part (17) are formed by integral components, The Claim 4 characterized by the above-mentioned. Liquid heating device.   Of the liquid heating chamber (28), the liquid inflow port (34) is arranged at one of the tip side and the base side of the heating unit (16), and the liquid discharge port (36) is arranged at the other side. The liquid heating apparatus according to claim 4, wherein the liquid heating apparatus is provided.

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