JPS6120709B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel vaporization accelerating device for, for example, an automobile engine, which applies heat only to the fuel in a mixture of fuel and air, and prevents heat from being lost to the air. be.

Conventional fuel vaporization accelerators have positive resistance-temperature characteristics, a Curie point at a specific temperature, and generate heat when energized, in order to facilitate cold starting and stabilize warm-up operation after starting. Some heaters are designed to expose a ceramic heater (PTC heater) to the flow of the air-fuel mixture, thereby promoting the vaporization of the fuel in the air-fuel mixture and preventing the fuel from being sucked into the engine in liquid form.

However, in the conventional type described above, a considerable amount of the heat generated from the ceramic heater is taken away by the intake air, and the fuel is indirectly heated by the intake air, but the temperature of the intake air Even if the temperature rises, its heat capacity is small and sufficient fuel vaporization is not carried out.Also, even if the fuel touches the heat-generating surface of the ceramic heater, the heat is absorbed by the intake air from the ceramic heater, so the fuel is not effectively vaporized. The problem is that it is not possible to promote Therefore, in order to promote the vaporization of the fuel, a large current must be passed through the ceramic heater to generate a large amount of heat, which places a heavy burden on the power source of the ceramic heater, such as an on-vehicle battery.

Therefore, in view of the above problems, the present invention provides a heat-resistant porous ceramic coating on the heat generating surface of the ceramic heater, thereby preventing the heat of the ceramic heater from being taken away by the intake air. Since the liquid fuel is absorbed by the porous ceramic coating, the heat of the ceramic heater is concentratedly applied to the fuel absorbed by the porous ceramic coating, thus effectively promoting the vaporization of the liquid fuel. It is an object of the present invention to provide a fuel vaporization promoting device that can achieve the above-mentioned results and reduce power consumption accordingly.

The present invention will be explained below with reference to embodiments shown in the drawings.
In FIGS. 1 and 2, reference numeral 1 denotes a rectangular ceramic heater according to the present invention, which has a positive resistance-temperature characteristic as shown in FIG. 3 and has a Curie point at a specific temperature. It is made of barium material. On both surfaces of the ceramic heater 1, positive and negative electrodes 2 and 3 made of nickel thin films are formed over the entire surface. Reference numeral 4 denotes a porous film made of aluminum oxide, which is provided on the surface of each electrode 2, 3, which is the heat generating surface of the ceramic heater 1. The coating 4 is formed by adding silica, which increases adhesiveness, to aluminum oxide powder and mixing and stirring the mixture with water to form a slurry.
A porous film 4 can be formed by soaking the material, drying it, and then firing it. Note that it is sufficient that the thickness of this porous film 4 is about 0.5 to 1.0 mm. When providing this porous coating 4, it goes without saying that the connection portions between each electrode 2, 3 and the lead wire of the power source 8 are masked.

The ceramic heater 1 is installed on the inner surface of a riser wall 7a of an intake passage 7 connecting an engine 5 and a carburetor 6, into which liquid fuel easily drips.
In addition, numeral 9 in the figure is a switch for energizing the ceramic heater 1.

Next, the apparatus of the present invention having the above configuration will be explained.
The liquid fuel in the air-fuel mixture generated in the vaporizer 6 falls onto the ceramic heater 1 due to gravity. Since this ceramic heater 1 is provided with a porous coating 4, liquid fuel is absorbed into this porous coating 4. Further, this porous film 4 acts as a heat insulating material and prevents the heat of the ceramic heater 1 from being taken away by the intake air in the mixture. Therefore,
Heat from the ceramic heater 1 is concentratedly applied to the liquid fuel absorbed by the porous coating 4, and this liquid fuel can be vaporized well.

As shown in Figure 3, the ceramic heater 1 has a positive resistance-temperature characteristic and a Curie point where the resistance value increases at a specific temperature. There's nothing to do.

Further, in the above embodiment, since the porous ceramic coating 4 has electrical insulation properties, the electrode 2
and the electrode 3 can be electrically insulated,
Therefore, when installing the ceramic heater 1 in the intake passage 7, no special electrical insulation structure is required between the electrodes 2 and 3.

The present invention is not limited to the above embodiments,
Various modifications are possible as shown below.

(1) The material of the porous coating 4 is not limited to aluminum oxide, but may include titanium oxide, magnesium oxide,
Any heat-resistant electrically insulating ceramic material such as beryllium oxide may be used.

(2) The shape of the ceramic heater 1 is not limited to a plate shape.
It may also have a honeycomb shape, a harmonica shape, etc. in which a large number of passages are formed. In addition, when such a honeycomb shape or a harmonica shape is used, a porous coating 4 may be provided on the surface of the many passages (heat generation surface).

(3) Ceramic heater 1 is also installed in intake passage 7.
It is not necessary to install it on the riser wall 7a, but it is sufficient to install it at a portion through which the air-fuel mixture passes.

(4) The present invention is not limited to having the carburetor 6, but can also be applied to injecting fuel upstream of the engine 5 with a fuel injection valve and mixing it with intake air.

(5) The present invention is also applicable to other uses than automobiles.

As described above, the device of the present invention includes a ceramic heater that has positive resistance-temperature characteristics, has a Curie point at a specific temperature, and generates heat when energized, and this ceramic heater is disposed in the intake passage. However, since a heat-resistant porous ceramic coating is provided on the heating surface of the ceramic heater, this porous ceramic coating prevents the heat of the ceramic heater from being taken away by the intake air in the mixture, and Since the liquid fuel in the air is absorbed by the porous coating, the heat of the ceramic heater is concentratedly applied to the liquid fuel absorbed by the porous coating, which improves the vaporization of this liquid fuel. can be promoted.

Furthermore, the porous coating described above can favorably promote the vaporization of liquid fuel without increasing the power consumption of the ceramic heater as in the prior art, which is effective in terms of power saving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention;
FIG. 2 is a partial sectional view showing a state in which the heater shown in FIG. 1 is installed in an intake passage, and FIG. 3 is a temperature-resistance characteristic diagram of the ceramic heater according to the present invention. 1... Ceramic heater, 2, 3... Electrode, 4
...porous coating, 5...engine, 6...carburizer, 7...intake passage.

Claims (1)

[Claims] 1. A ceramic heater that has a positive resistance-temperature characteristic, has a Curie point at a specific temperature, and generates heat when energized is placed in the intake passage for the air-fuel mixture that connects the engine and the fuel supply system. A fuel vaporization accelerator for an engine, characterized in that a heat-resistant porous ceramic coating is provided on a heat-generating surface.