JPS6331664B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an intake air heating device for an internal combustion engine.

[Prior Art and Problems] In a fuel supply device that produces a mixture of fuel and air using, for example, a carburetor and supplies this to an internal combustion engine via an intake pipe, when the outside air temperature is low, Particularly when the internal combustion engine is not sufficiently warmed up, the fuel does not mix sufficiently with the air, and a portion of the fuel flows as a liquid film along the walls of the carburetor and intake pipe. The moving speed of this fuel liquid film flow is much slower than the flow speed of air, which makes it difficult to maintain the air-fuel ratio of the air-fuel mixture that is combusted at one time in the internal combustion engine at an ideal state.

For this reason, devices that heat intake air to make it easier to vaporize fuel are being considered, and devices that use internal combustion engine exhaust or cooling water have been commercialized. However, when the internal combustion engine is not sufficiently warmed up, the exhaust gas temperature and the cooling water temperature are low, so these methods do not provide sufficient effects. For this reason, consideration has begun to be given to using an electric heater in conjunction with the vehicle until warm-up is insufficient. What is important at this time is to selectively heat only the liquid film flow of fuel in the intake air; heating the already atomized fuel or air will result in a loss of power. .

The present invention has been made in view of the above points, and
It is an object of the present invention to provide an intake air heating device for an internal combustion engine that selectively heats and vaporizes a liquid film flow of fuel and reduces power loss.

[Means for solving problems]

In the present invention, a metal heat radiation part having a flange part is provided in the mixture passage that supplies fuel and air to the internal combustion engine, and an annular groove space with the flange part as the bottom is provided in the mixture passage. It has a PTC ceramic heater having a flat part, and the PTC ceramic heater is provided so that the flat part is in close contact with the back surface of the flange part so that the flange part serves as a heat radiation surface, and the PTC ceramic heater is installed in the axial direction. Adopt the technical means of providing electrodes for conducting electricity.

[Effect]

According to the present invention, the liquid film material of the fuel is selectively guided into the annular groove space, and in this groove space, the PTC ceramic heater provided in close contact with the flange part of the metal heat dissipation part forming the bottom surface of the groove space is used. It is heated and efficiently vaporizes the liquid fuel guided and retained in the annular groove space.

At this time, the PTC ceramic heater is installed on the back of the flange of the metal heat dissipation part, so the flange comes into contact with the air-fuel mixture and the heater itself does not come into direct contact with the air-fuel mixture, so there is no risk of damage due to thermal shock. Since the PTC ceramic heater is an annular thin plate and conducts electricity in its axial direction, it is easy to manufacture the PTC ceramic heater, especially the electrodes.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. 1 is a vaporizer. The carburetor 1 is connected to the atmosphere at its upstream side and to the internal combustion engine at its downstream side, and has the function of mixing fuel into air introduced from the atmosphere to form an air-fuel mixture and supplying the mixture to the internal combustion engine. The carburetor 1 has at least two fuel supply nozzles, one of which is a main nozzle (not shown) located above the throttle valve 2, and the other one is a slow nozzle located below the side of the throttle valve 2. It is 3. Fuel from the throat chamber 4 and air from the air bleed 5 are supplied to the slow nozzle 3 in the form of an emulsion. This emulsion passage has an adjustment screw 6 for adjusting it.
is provided.

The carburetor 1 is fixed to the intake pipe 8 by the flange 7 at the bottom thereof, but a heat insulator 10 is interposed between the flange 9 of the intake pipe 8 and the flange 7 of the carburetor 1. ing. The heat insulator 10 is generally a heat insulating resin plate, but in the present invention, the heat insulator 10
It is characterized by having an intake air heating device 11 built into it.

The metal heat radiation part 12 of the intake air heating device 11 is pipe-shaped with a flange part 15 and is made of aluminum. The inner diameter of the pipe portion 13 of the heat radiating portion 12 is the same as that of the air-fuel mixture passage (usually referred to as a barrel) 14 of the carburetor 1 . The inner circumferential side of the flange portion 15 of the heat dissipating section 12 is exposed to the passage 14, and the outer circumferential side is covered with resin 16, which is the main body of the heat insulator 10. As a result, flange part 1
At the exposed part of 5, there is a flange 7 of the carburetor.
An annular groove space 17 is formed by using the lower part of the heat insulator as an upper wall, the upper surface of the flange 15 of the heat radiation part as a lower wall, and the resin main body 16 of the heat insulator as a back wall. The axial center of this annular groove space 17 is eccentric from the axial centers of the pipe portion 13 of the heat radiation section 12 and the barrel 14 of the carburetor, and is closer to the slow nozzle 3 side of the carburetor. Therefore, the depth of this annular groove space 17 is larger (deeper) on the slow nozzle side than on the opposite side. Flange 15 of heat radiation part 12
The flat surface of the PTC ceramic heater 18 is in close contact with the back surface of the PTC ceramic heater 18.

PTC ceramic is mainly made of barium titanate, mixed with Pb, Mn, etc. and fired, and has a Kyuri point at approximately 150°. A characteristic of this PTC ceramic is that it exhibits a small electrical resistance at temperatures below this Curie point, and an extremely high electrical resistance at temperatures above this Curie point.

The PTC ceramic heater 18 is an annular thin plate, and has approximately the same shape and dimensions as the lower surface of the flange 15. The lower surface of this PTC ceramic heater 18 is supported by stainless wool 19. Stainless wool is made by knitting and forming thin stainless steel wires with a diameter of about 0.1mm.
It has an annular shape similar to the ceramic heater 18.
This stainless steel wool 19 is in close contact with the lower surface of the PTC ceramic heater 18, which is the positive electrode, to conduct electricity and also to have a buffering effect. Furthermore, it also has a heat insulating function. A copper electrode plate 20 is provided on the lower surface of this stainless wool 19. The electrode plate 20 is also an annular thin plate having the same shape as the PTC ceramic heater 18. A rectangular copper plate 2 is provided at a predetermined location on the lower surface of the electrode plate 20.
1 is welded, and this copper plate 21 penetrates the resin 16 that is the main body of the heat insulator and protrudes to the outside. This copper plate 21 is the terminal of the positive electrode and is connected to the battery.

A similar copper plate 22 is also welded to the upper surface of the flange 15 of the heat dissipation section 12, and this serves as a ground electrode terminal. PTC ceramic heater 18,
The stainless wool 19 and the electrode plate 20 have an insulator 23 that is a resin pipe so that the annular inner peripheral surface thereof does not come into contact with the pipe 13 of the heat radiation section 12 and cause an electrical short circuit.

As described above, the heat dissipation section 12, PTC ceramic heater 18, stainless wool 19, electrode plate 20,
The intake air heating device 11 constituted by the terminals 21 and 22 is entirely built into the resin 16 that is the main body of the heat insulator 10, except for a part of the heat radiating section 12. As a method for incorporating it, a mold may be used, or appropriately divided resin may be bonded after being incorporated. As a result, the heat insulator 10 incorporating the intake air heating device 11 can be handled in the same way as a normal heat insulator, apparently as a single plate.

The mixture passage 14, which continues vertically into the carburetor 1, the heat insulator 10, and the intake pipe 8, changes its direction horizontally within the intake pipe 8 and branches as many as the number of cylinders that make up the internal combustion engine. do. The intake manifold 24 has a plurality of intake manifolds, for example, the most common four intake manifolds.
This figure shows a cross section of one of the pieces. A water jacket 25 is provided at the bottom of the intake pipe 8, including the intake manifold 24, into which cooling water 26 for the internal combustion engine is introduced.

Next, the operation of the above-mentioned constituent device will be explained. When the key switch is turned on to start the internal combustion engine, the intake air heating device 11 is energized in conjunction with this. The current from the battery is passed through the positive electrode terminal 21 and the electrode plate 2.
0, through the stainless wool 19 to the PTC ceramic heater 18, and then to the PTC ceramic heater 1
8 is energized in the axial direction (vertical direction in FIG. 1).
The current generated by the PTC ceramic heater 18 passes through the flange 15 of the heat radiation section 12, the ground electrode terminal 22, and falls to the ground. At this time, the temperature of the PTC ceramic heater 18 is the same as the atmospheric temperature and its electrical resistance is small, so it allows a large current to reach the Curie point of 150° C. almost instantaneously. cuyuri point
When the temperature exceeds 150°C, the electrical resistance becomes extremely large, the current is suppressed, and the temperature is forced to drop, so the temperature of the PTC ceramic heater 18 is naturally maintained at 150°C, which is about 150°C above the Kyuri point. As a result, the heat dissipation section 12 also receives heat from the PTC ceramic heater 18, and its temperature rises to about 100° C. on the upper surface of the flange 15 and to about 60° C. on the inner circumference of the pipe 13. When the internal combustion engine starts, air introduced from the atmosphere flows into the intake pipe 8 through the gap between the throttle valve 2 in the barrel 14. Fuel is supplied from the slow nozzle 3 to be mixed with the air. At this time, if the fuel temperature is low, the air temperature is low, and the wall temperature of the barrel is also low, the fuel supplied from the slow nozzle 3 cannot be sufficiently atomized, and the liquid film remains as it is. It descends down the barrel wall while forming a . After the liquid film flow of fuel reaches the lowest end of the barrel, it passes along the lower surface of the flange 7 and enters the annular groove space 17 provided in the heat insulator 10 . The liquid film of fuel that has entered the annular groove space 17 is transferred to the heat dissipation section 12 that forms one surface of the annular groove space 17.
is heated and vaporized by the flange 15 of. The vaporized fuel leaves the wall and flows into the intake pipe along with the airflow.

In the above embodiment, the inner diameter of the pipe 13 of the heat radiating section 12 is approximately the same as the diameter of the barrel 14 of the carburetor, but the inner diameter of the pipe 13 may be made smaller. Furthermore, the pipe 13 may be eccentric to the opposite side of the slow nozzle 3. In this way, the effective area for heating the liquid film of fuel can be increased.

Furthermore, although it has been described that the PTC ceramic heater 18 is an annular thin plate and is integrally molded,
This may be a tiled arrangement of divided pieces. At this time, the area on the opposite side of the slow nozzle 3 may be reduced or omitted.

Furthermore, although the heat dissipation section 12 of the intake air heating device 11 has been described as having the pipe 13 and the flange 15, the minimum requirement of the present invention is that the flange 1
5, and the pipe 13 may be omitted.
At this time, it is sufficient to bring the resin 16, which is the core of the heat insulator 10, also to the part where the pipe 13 should be.

〔Effect of the invention〕

As described above, the present invention heats the annular groove space rather than heating the inside of the air-fuel mixture passage or its wall surface itself.
As a result, only the liquid film flow of fuel that has entered this groove space is heated, so that a sufficient effect can be obtained with a minimum amount of heat.

Further, since the groove space is annular, the liquid film flow of the fuel must necessarily pass through the groove space, and in this case, it is heated and vaporized, so that the liquid film flow of the fuel cannot continue.

Since the flat part of the PTC ceramic heater is in close contact with the flange part and serves as a heat dissipation surface, the bottom of the annular groove space can be effectively heated.Also, since the electrode is axially energized, the shape of the electrode is easy and productivity is high. There is an effect. Furthermore, since the PTC ceramic heater does not come into direct contact with the air-fuel mixture, there is no risk of damage due to thermal shock.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line A--A in FIG. 1... Carburetor, 3... Slow nozzle, 8... Intake pipe, 10... Heat insulator, 11...
Intake air heating device, 14...Mixture passage, 17...Annular groove, 18...PTC ceramic heater as a heating element, 24...Intake manifold.

Claims (1)

[Scope of Claims] 1. A metal heat dissipation section having a flange is provided in a mixture passage that supplies fuel and air to an internal combustion engine, and an annular groove space with the flange as a bottom surface is provided in the mixture passage. , has a PTC ceramic heater which is an annular thin plate and has a flat part, and the said flange part serves as a heat radiation surface.
An intake air heating device for an internal combustion engine, characterized in that a PTC ceramic heater is provided so that its flat surface is in close contact with the back surface of the flange, and an electrode is provided for axially energizing the PTC ceramic heater. 2. The axial center of the air-fuel mixture passage leading from the carburetor to the intake manifold and the axial center of the annular groove provided in a part thereof are eccentric to each other, and the annular groove is located in the position of the slow nozzle of the carburetor. The intake air heating device for an internal combustion engine according to claim 1, wherein the intake air heating device for an internal combustion engine is installed so as not to be deep on the side.