JP5180173B2 - Fuel heating device - Google Patents

Description

  The present invention relates to a fuel heating device that is provided between a fuel supply pipe and a fuel injection valve and heats the fuel supplied from the fuel supply pipe to the fuel injection valve, and prevents the fuel heating apparatus from fraying. In addition, the present invention relates to a technique for efficiently heating the fuel.

  In an internal combustion engine that uses a fuel injection valve to inject fuel, it is necessary to warm the fuel supplied to the fuel injection valve in order to enable a smooth start even at low temperatures. Therefore, a fuel heating apparatus is known in which a heater is provided in a fuel supply pipe so that fuel heated by the heater is supplied to a fuel injection valve. However, in such a fuel heating device, even if the fuel is heated in the fuel supply pipe, it is difficult to uniformly heat the entire fuel supplied to the fuel injection valve. Therefore, unwarmed fuel is supplied to the fuel injection valve. May be supplied. In such a case, there has been a problem that starting of the internal combustion engine becomes unstable. In order to solve this problem, an area for heating the fuel is provided in the vicinity of the upstream side of the fuel injection valve in the fuel supply pipe, the fuel is heated by the heater in this area, and only the heated fuel is supplied to the fuel supply pipe. Has been proposed (see Patent Document 1).

JP-A-5-26130

  However, in the invention described in Patent Document 1, the fuel is vaporized by heating of the heater to form bubbles, and when this bubble fills the heating region, the fuel heating device is in an empty state. For this reason, there is a possibility that not only the fuel is not efficiently heated, but also an increase in the fuel pressure is hindered and the fuel supply becomes unstable, or the heater heating wire is disconnected.

  The present invention has been devised to solve the problems imposed on the prior art, and its main purpose is to prevent the fuel heating device from being blown and to efficiently heat the fuel. Is to plan.

  In order to solve such a problem, the first invention is provided between the fuel supply pipe (2) and the fuel injection valve (4), and from the fuel supply pipe (2) to the fuel injection valve (4). A fuel heating device (3) for heating fuel to be supplied, which defines a heating chamber (6), and has a plurality of inlets (7a) through which fuel flows from a fuel supply pipe (2) and a fuel injection valve ( 4) A heater housing (7) having an outlet (7b) through which fuel flows out, and a heater (8) provided in the heating chamber (6) and having a heat generating part (9h) for heating the fuel by heating. The heater housing (7) has an upper wall (7u) that is located above the heat generating portion (9h) and is inclined with respect to the horizontal plane, and a plurality of inlets (7a) are formed on the upper wall (7u). ) And arranged at different height positions.

  When the fuel is overheated by the heating of the heater, bubbles are generated around the heat generating portion, and the generated bubbles move upward in the heating chamber. According to the present invention, the heater housing has an upper wall that is positioned above the heat generating portion and is inclined with respect to the horizontal plane, and the plurality of inlets are formed on the upper wall, so that the heater housing moves upward along the upper wall. The moved bubbles flow out from the inlet arranged on the higher side to the fuel supply pipe. When the bubbles flow into the fuel supply pipe, the fuel in the fuel supply pipe flows into the heating chamber from the inlet arranged on the lower side. As a result, the fuel in the heating chamber flows into the fuel supply pipe through the inlet arranged on the higher side, and the fuel in the heating chamber passes through the inlet arranged on the lower side in the fuel supply pipe. Convection flowing into the For this reason, the temperature of the fuel in the heating chamber is lowered, the generation of bubbles is suppressed, and the bubbles are not accumulated in the heating chamber, so that the fuel heating device can be prevented from being blown. Further, the fuel in the heating chamber and the fuel supply pipe can be efficiently and evenly heated. Furthermore, since the bubbles that have entered the fuel supply pipe are cooled by the fuel in the fuel supply pipe and returned to the liquid, the fuel can be used effectively.

  Further, according to a second invention, in the fuel heating device (3) according to the first invention, the plurality of inflow ports (7a) are two, and one (7au) is near the upper end of the upper wall (7u). The other side is arranged near the lower end of the upper wall (7 ul).

  According to the present invention, since the two outlets are arranged in the vicinity of the upper and lower ends of the upper wall, the two outlets are separated from each other to increase the convection, and the fuel in the heating chamber and the fuel supply pipe is totally replaced. Therefore, the fuel in the heating chamber and the fuel supply pipe can be heated more effectively. In addition, since the high-side inflow port is disposed near the upper end of the upper wall, it becomes easier for bubbles to enter the fuel supply pipe, and bubbles can be prevented from remaining in the heating chamber. In addition, the lower side inlet is arranged near the lower end of the upper wall, so that cooler fuel in the fuel supply pipe can flow into the heating chamber, and the fuel in the heating chamber and the fuel supply pipe is heated as a whole. can do.

  Further, according to a third aspect of the present invention, in the fuel heating device (3) according to the first or second aspect of the present invention, the opening area of the inflow port (7au) disposed at a higher position is a flow position disposed at a lower position. It is characterized by being larger than the opening area of the inlet (7 ul).

  The warmed fuel rises and accumulates at a high position in the heating chamber. Therefore, for example, when the fuel is not heated by the heater, if the opening area of the high inlet and the opening area of the low inlet are the same, the cold fuel in the fuel supply pipe flows into the heating chamber first. Resulting in. According to this invention, the opening area of the high-side inlet is larger than the opening area of the low-side inlet, so that the fuel enters the heating chamber from the higher-side inlet. That is, the warm fuel on the higher side in the fuel supply pipe enters the heating chamber first, and the fuel heating efficiency can be increased.

  According to a fourth invention, in the fuel heating device (3) according to the first to third inventions, the heater housing (7) has a cylindrical shape, and its axis (A) is inclined with respect to a horizontal plane. The heater (9) has a rod shape and is provided substantially along the axis (A) of the heater housing (7) so that the tip (9a) is on the lower side, and the heating part (9h) Is arranged on the tip (9a) side.

  The fuel heated by the heat generating part rises in the heating chamber, and the cold fuel flowing in from the inflow port descends in the heating chamber. According to the present invention, the rod-shaped heater is arranged in a state inclined with respect to the horizontal surface with the tip down, and the heat generating part is arranged on the tip side, so that the heating chamber returns to the inclination direction of the heater housing. Since convection occurs and the generated bubbles are likely to rise on the convection, the bubbles can be reliably collected on the upper wall. Since the heater housing has a cylindrical shape, the bubbles rising along the upper wall are collected at the ridgeline (center line) of the curved upper wall, and the bubbles rise aslant along the center line. It can be more reliably collected at the inlet. Thereby, it becomes easy for bubbles to return to the fuel supply pipe, and bubbles can be prevented from remaining in the heating chamber.

  As described above, according to the present invention, the fuel heating device can be prevented from being blown, the heater can be disconnected from being blown, and the fuel can be efficiently heated.

It is a perspective view of the fuel heating unit which concerns on embodiment. It is sectional drawing of the fuel heating apparatus which concerns on embodiment. It is explanatory drawing of the effect by the fuel heating apparatus which concerns on embodiment.

  Hereinafter, a fuel heating device 3 according to the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings. When indicating the direction of each member or each part, when the fuel heating unit 1 is installed on an automobile engine stopped on a horizontal flat road, the vertical direction is set as a reference and the vertical direction is set as a reference. And right and left orthogonal to this shall be defined.

  As shown in FIG. 1, a fuel heating unit 1 is provided in an in-line four-cylinder automobile alcohol engine (hereinafter abbreviated as “engine”) using ethanol as a main fuel, and the fuel heating unit 1 supplies fuel. A fuel heating device 3 for heating the fuel supplied by the pipe 2 and a shaft that is provided in the intake passage of the engine so as to inject the fuel heated by the fuel heating device 3 and supply it to the fuel chamber of the engine One fuel injection valve 4 is provided for each cylinder.

  The fuel supply pipe 2 has a flat distribution portion 2a having a large cross-sectional area at the downstream end thereof, so that fuel can be distributed to each fuel heating device 3 with equal pressure. Although not shown, the upstream end of the fuel supply pipe 2 is connected to a fuel pump as fuel supply means. When the ignition switch is turned on, the fuel pump is driven and a predetermined pressure is applied. Send the fuel with.

  The fuel heating device 3 is attached to the lower surface of the distribution unit 2 a where the fuel outlet is formed, that is, the downstream end of the fuel supply pipe 2. The fuel heating device 3 has a built-in heating wire as a heating element, and the current from the battery to the heating wire is duty-controlled by an ECU (Electric Control Unit) according to the temperature of the engine coolant, etc. The fuel in the heating chamber 6 is appropriately heated. The fuel heating device 3 starts to operate when a first start operation is performed by an engine start button (not shown), performs fuel preheating (starting heating), and starts the engine by a second start operation. When the fuel injection by the fuel injection valve 4 is started, the heating is switched to the post-starting heating and the heating of the fuel is continued.

  The fuel injection valve 4 is connected to the downstream side in the fuel flow direction with respect to the fuel heating device 3. The fuel injection valve 4 incorporates an electromagnetic valve that is driven and controlled by the ECU, and injects a predetermined amount of fuel toward the combustion chamber of the engine at a predetermined time by opening and closing the electromagnetic valve. The fuel heating device 3 and the fuel injection valve 4 are connected via a base plate 10 for integrating the respective members as the fuel heating unit 1, and all the fuel heating devices 3 and the fuel injection valves 4 are connected. By being attached to one base plate 10 and being unitized, the assembly to the engine is facilitated, and the assembly accuracy of the fuel injection valve 4 to the engine can be increased.

  As shown in FIG. 2, the fuel heating device 3 is provided between the fuel supply pipe 2 and the fuel injection valve 4, and includes a heater housing 7 that defines the heating chamber 6, and a heater 8 attached to the heater housing 7. It has.

  The heater housing 7 has a substantially cylindrical shape whose axis A is inclined with respect to the horizontal direction. More specifically, the heater housing 7 has a long cylindrical shape whose axial length is longer than the diameter, and is attached to the engine with the axis A inclined at about 45 degrees with respect to the horizontal plane. An opening 7 o for inserting the heater 8 is formed at the upper shaft end of the heater housing 7.

  The heater 8 includes a rod-shaped heater member 9 having a heat generating portion 9h that generates heat and heats the fuel on the tip side. The heater 8 is attached to the heater housing 7 in such a manner that the heater member 9 is inserted into the heating chamber 6 through the opening 7o. The heater member 9 extends coaxially along the axis A of the heater housing 7 so that the front end 9a is on the lower side and a predetermined gap is formed between the front end 9a and the heater housing 7. 7 is accommodated. A heating part 9 h is provided on the tip 9 a side of the heater member 9. The heating part 9h has a built-in heating wire that has a large resistance and generates heat by energization, and is a part that maintains a relatively large amount of heat by transmitting the heat of the heating wire and is in a heating state. It is set to about 70% to 80% on the front end side of the heater member 9.

  Accordingly, the upper wall 7u of the heater housing 7 located above the heat generating portion 9h covers the upper portion of the heat generating portion 9h in a state where the curved wall forming a part of the cylinder is inclined. The heater housing 7 has an upper wall 7u on the ridge line 7r connecting the highest points of the heater housing 7 in each cross section orthogonal to the axis A, that is, on the center line of the upper wall 7u, from the fuel supply pipe 2 to the heating chamber 6u. Two circular inlets 7au and 7al are formed to allow fuel to flow into the tank. An inflow port (hereinafter referred to as an upper inflow port) 7au disposed on the upper side is disposed near the uppermost portion of the upper wall 7u, and an inflow port (hereinafter referred to as a lower inflow port) 7al disposed on the lower side is The upper wall 7u is disposed in the vicinity of the lowermost portion. That is, the two inflow ports 7au and 7al are arranged at different heights, the upper inflow port 7au is arranged at a position higher than the heat generating portion 9h, and the lower inflow port 7al is equivalent to the heat generating portion 9h. It is arranged at the height position. The opening area of the upper inlet 7au is made larger than the opening area of the lower inlet 7al.

  On the other hand, the lower wall 7l of the heater housing 7 positioned below the heat generating part 9h is a circular cylindrical wall part 7lt that forms a part of an inclined cylinder and a circular shape that closes the lower shaft end of the inclined cylinder. And a bottom wall portion 7lb. The lower wall 7l of the heater housing 7 has a heating chamber in the vicinity of the lowest part on the valley line 7v connecting the lowest points of the heater housing 7 in each cross section orthogonal to the axis A, that is, the center line of the cylindrical wall portion 7lt. An outflow port 7 b through which fuel flows out from 6 toward the fuel injection valve 4 is formed. Therefore, the outflow port 7b is disposed at a position lower than the heat generating portion 9h, and is disposed on the side opposite to the inflow port 7a across the heat generating portion 9h.

  A through hole 10 a is formed in the base plate 10 at a position aligned with the outlet 7 b of the heater housing 7. The fuel injection valve 4 is provided with a fuel inlet 4a at the base end of the shaft, and the axis B is aligned with the heater housing 7 so that the fuel inlet 4a is aligned with the through hole 10a. It is attached to the base plate 10 so as to be in a direction orthogonal to the axis A. Accordingly, the axis B of the fuel injection valve 4 is inclined by about 45 degrees with respect to the horizontal plane and is orthogonal to the cylindrical wall portion 7lt of the lower wall 7l of the heater housing 7. By arranging each member in this way, the lower inlet 7al of the heater housing 7 is positioned on the axis B of the fuel injection flight 4, and the upper inlet 7au of the heater housing 7 is the axis of the fuel injection valve 4. Offset to the upper side of B. In other words, the inlets 7au and 7al and the outlet 7b of the heater housing 7 are formed so as to be orthogonal to the cylindrical wall portion, and their axes (fuel flow direction) are parallel to the lower inlet 7al and the outlet. The outlet 7b extends on the same straight line.

  Next, with reference to FIG. 3, the effect by the fuel heating apparatus 3 which concerns on embodiment is demonstrated. As shown to (A), in the fuel heating apparatus 3 comprised in this way, since the air bleeding means is not provided, the air which was not discharged | emitted at the time of the first fuel supply remains inside. Then, before the fuel is heated, that is, in a state where the ignition switch is switched from the ACC position to the IG position and fuel having a predetermined pressure is supplied by the fuel pump, the heating chamber 6 and the distribution section of the fuel supply pipe 2 In 2a, compressed air is mixed in an upper portion thereof, more specifically, a portion higher than the upper inflow port 7au.

  In this state, when the heat generating portion 9h generates heat by the first start operation, the fuel around the heat generating portion 9h is heated as shown in (B), and the warmed fuel moves upward in the heating chamber 6. The warm fuel rises diagonally along the upper wall 7u of the heater housing 7, and the cold fuel moves downward along the lower wall 7l of the heater housing 7, so that the heater fuel 7 circulates in the clockwise direction in the figure. Convection occurs, and the fuel is heated evenly. In addition, the outflow port 7b of the heater housing 7 is arranged so that the fuel flowing out does not hinder convection. When the fuel in the heater housing 7 is overheated by the heat generating portion 9h, the fuel around the heat generating portion 9h is vaporized into bubbles, and the bubbles rise substantially vertically due to the difference in specific gravity and convection. And since the heater housing 7 has the upper wall 7u which inclines with respect to a horizontal surface above the heat generating part 9h, the bubbles rising substantially vertically and hitting the upper wall 7u of the heater housing 7 follow the upper wall 7u. Rise diagonally. At this time, even if the bubble hits a portion other than the ridge line 7r on the upper wall 7u, it rises so as to be collected on the ridge line 7r.

  Then, the bubbles rising along the ridge line 7r flow out to the distribution part 2a of the fuel supply pipe 2 through the upper inlet 7au formed in the vicinity of the uppermost part on the ridge line 7r without accumulating in the heating chamber 6. When the bubbles flow into the distribution unit 2a, the fuel in the distribution unit 2a flows into the heating chamber 6 from the lower inlet 7al. Thereby, the warm fuel in the heating chamber 6 flows into the distribution part 2a via the upper inlet 7au, and the cold fuel in the distribution part 2a flows into the heating chamber 6 via the lower inlet 7al. Convection is generated that circulates counterclockwise in the figure across 2 a and the heating chamber 6. For this reason, the temperature of the fuel in the heating chamber 6 is lowered, the generation of bubbles is suppressed, and the bubbles are not accumulated in the heating chamber 6, so that the fuel heating device 3 is prevented from being blown. Further, after the fuel in the heating chamber 6 is heated, the fuel in the heating chamber 6 and the distribution unit 2a is efficiently and evenly heated. In addition, since the bubble which entered the distribution part 2a is cooled by the cold fuel in the distribution part 2a and returns to the liquid, the fuel is effectively used. Therefore, a large amount of bubbles remain in the distribution unit 2a and does not hinder the increase in fuel pressure.

  Since the upper outlet 7au is arranged in the vicinity of the upper end of the upper wall 7u and the lower outlet 7al is arranged in the vicinity of the lower end of the upper wall 7u, the convection returning in a counterclockwise direction increases, and the heating chamber 6 In addition, since the fuel in the distribution unit 2a is replaced as a whole, the fuel in the heating chamber 6 and the distribution unit 2a is more effectively heated evenly. Further, since the upper inlet 7au is disposed in the vicinity of the upper end of the upper wall 7u, not only the air remaining in the heating chamber 6 is reduced, but also the bubbles can easily enter from the upper inlet 7au into the distributor 2a. Is less likely to remain in the heating chamber 6. Further, since the lower inflow port 7al is disposed in the vicinity of the lower end of the upper wall 7u, cooler fuel in the distribution unit 2a flows into the heating chamber 6, and the fuel in the heating chamber 6 and the distribution unit 2a. Is heated as a whole, and the fuel temperature in the heating chamber 6 can be efficiently reduced.

  Thereafter, when the engine is started by the second start operation, the fuel in the heater housing 7 is injected by the fuel injection valve 4, and the fuel is sequentially supplied from the distributor of the fuel supply pipe 2 to the heating chamber 6. Then, since the opening area of the upper inlet 7au is formed larger than the opening area of the lower inlet 7al, the fuel in the distributor 2a enters the heating chamber 6 from the upper inlet 7au. That is, the fuel in the upper part of the distribution part 2a that has been warmed by the heating by the heater member 9 first flows into the heating chamber 6, and the fuel heating efficiency is increased.

  Since the outlet 7b of the heater housing 7 is provided on the opposite side of the inlet 7a across the heat generating portion 9h, the fuel flowing into the heating chamber 6 from the inlet 7a generates heat on the way to the outlet 7b. It is reliably heated by the part 9h. And since the outflow port 7b is provided in the position lower than the heat-emitting part 9h, it becomes difficult for the bubble which generate | occur | produced in the heating chamber 6 to flow out from the outflow port 7b, and a bubble is supplied to the fuel injection valve 4. Is prevented.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. For example, in the above embodiment, the fuel heating device 3 according to the present invention is applied to an alcohol engine that uses ethanol as a main fuel, but it can also be applied to an engine that uses other components as fuel, such as light oil and gasoline, Of course, the present invention can be applied to engines other than the in-line four cylinders. In the above embodiment, the heater housing 7 has a long cylindrical shape and the upper wall 7u is curved. However, these shapes are not limited to this, and for example, the heater housing is a cube or a rectangular parallelepiped. Further, it may be a polygonal cylinder (cylinder) shape, a spherical shape, or the like, and may be a single plane in which the upper wall is inclined with respect to a horizontal plane, a combination of planes, or a spherical surface curved in two directions. In addition to these changes, the specific configuration and arrangement of each member can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Fuel heating unit 2 Fuel supply pipe 2a Distribution part 3 Fuel heating apparatus 4 Fuel injection valve 6 Heating chamber 7 Heater housing 7a Inlet 7b Outlet 7u Upper wall 7l Lower wall 8 Heater 9 Heater member 9h Heat generating part

Claims (4)

A fuel heating device that is provided between a fuel supply pipe and a fuel injection valve and heats fuel supplied from the fuel supply pipe to the fuel injection valve,
A heater housing defining a heating chamber and having a plurality of inflow ports through which fuel flows from the fuel supply pipe and an outflow port through which fuel flows out toward the fuel injection valve;
A heater provided in the heating chamber and having a heat generating part that heats the fuel by generating heat;
The heater housing has an upper wall that is located above the heat generating portion and is inclined with respect to a horizontal plane, and the plurality of inflow ports are formed on the upper wall and arranged at different height positions. The fuel heating apparatus characterized by the above-mentioned.   The plurality of inflow ports are two, one of which is disposed near the upper end of the upper wall and the other is disposed near the lower end of the upper wall. Fuel heating device.   The fuel heating device according to claim 1 or 2, wherein an opening area of the inlet arranged at a higher position is larger than an opening area of the inlet arranged at a lower position. . The heater housing has a cylindrical shape and is installed with its axis inclined with respect to a horizontal plane,
2. The heater according to claim 1, wherein the heater has a rod shape, is provided substantially along the axis of the heater housing so that a tip of the heater is on the lower side, and the heat generating portion is disposed on the tip side. The fuel heating apparatus according to claim 3.

Images