JPH0115896Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an intake burner structure for heating intake air flowing through the intake system of an internal combustion engine such as a diesel engine to improve engine startability. The present invention relates to an intake burner structure that can efficiently vaporize supplied fuel oil despite having a simple structure, and can contribute to improving the startability of an engine through reliable ignition performance and stable combustion.

[Technical background of the invention and its problems]

In general, internal combustion engines, and diesel engines in particular, generate spontaneous combustion only by compressing the intake air in the cylinder in environments where the temperature of the air being taken in is relatively low (cold regions, cold times, etc.). It is difficult to induce ignition, and a smooth engine start can hardly be expected.

In order to overcome this situation, as shown in Fig. 1, the intake system 2 of the engine 1 is equipped with a
The engine 1 uses this combustion heat to heat the circulating intake air and
An intake burner 3 is provided to improve the startability of the engine.

Conventionally, as this type of intake burner, the one illustrated in FIG. 2 is known. The intake burner 3a has an outer cylindrical body 4 forming an outer shell thereof, which is attached to an intake pipe 5 such as an intake manifold by passing through it. A heating resistor body 7 formed by winding it into a coil is built in, and a heater 9 formed by compactly filling powder 8 such as magnesium oxide is provided. This heater 9 is connected to the intake system 2
The fuel oil supplied at the outer circumferential surface of the end (hereinafter referred to as the "vaporizing end") 11 located on the outside and facing the fuel supply port 10 is received, and this fuel oil is sequentially passed along the outer circumferential surface in the longitudinal direction. While being transferred, the intake air is heated and vaporized, and is further heated on the outer circumferential surface of the end (hereinafter referred to as the "combustion end") 12 extending inward of the intake system 2 to ignite and burn the intake air, thereby heating the intake air. It is configured as follows. In particular, a cylindrical holder 13 is provided inside the outer cylinder 4 along its longitudinal direction to cover the outer circumferential surface of the heater 9 from the outside.
It is configured to promote vaporization of fuel oil transferred from the side to the combustion end 12. Note that 20 is a cylindrical sleeve for preventing the combustion flame from being blown out by intake air passing at high speed.

However, in the conventional method, (i) the metal sheath 6 is heated via the magnesium oxide powder 8 filled in the heater 9 to hold and fix the heat generating resistor 7, so it takes a long time to heat the metal sheath 6; (ii) Due to the compressed and packed magnesium oxide powder 8, it is not possible to set the heating resistor 7 installed therein at a predetermined pitch, and the heater 9 cannot be set to the desired temperature distribution. Since it cannot be heated, it cannot bring about the necessary effects, and it also has drawbacks such as poor reliability in terms of performance.

Therefore, the inventors of the present invention first developed an intake burner 3 as shown in FIG.
b, but in this, the heater 14
Regarding the structure, the entire heater 14 is molded from a ceramic body, and the heat generating resistor body 15 made of tungsten wire is embedded inside the heater 14, thereby taking advantage of the heat resistance of the ceramic body and the rapid temperature rising property of tungsten, which can generate high heat. However, in the case of such a new idea, there are shape limitations (at least a pair of opposing side surfaces are molded in parallel) in the production of the heater, which will be described later. As shown in FIGS. 4 and 5, if the holder 13 is formed into a cylindrical shape, a large clearance will be formed between the holder 13 and the heater 14, which has a substantially rectangular cross section. If the fuel oil is supplied by pouring it onto the surface, the fuel oil cannot be smoothly vaporized in the area covered by the holder 13, and the heater 1
4 and the holder 13, and there is a risk that stable combustion cannot be achieved on the combustion end 12 side.Therefore, it has been desired to solve this problem.

[Purpose of invention]

The present invention was devised in view of the above-mentioned problems, and its purpose is to efficiently vaporize the supplied fuel oil while having a simple structure, and to achieve steady ignitability and stable combustion. An object of the present invention is to provide an intake burner structure that can contribute to improving the startability of an engine.

[Example of idea]

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

The features of this invention are as shown in Figures 6 and 7.
As shown in the figure, the shape is limited so that the fuel heated and supplied by the heating resistor (not shown) is transferred along its outer peripheral surface in the longitudinal direction, heated, vaporized, and combusted. heater 14
and a holder 16 for covering the outer circumferential surface of the heater 14 from the outside to promote vaporization of the fuel, and the other configurations are substantially the same as the above-mentioned intake burner. In addition, an example of the method for manufacturing the ceramic heater used in the present invention is as shown in FIG.
. . . A ceramic powder 17 is filled between them, and the heater 14 is formed by hot press molding the ceramic powder 17 using a molding press body 18 pushed between the molding partition walls 19 . Therefore, in the heater, at least a pair of opposing side surfaces 14a separated by the molding partition walls 19 are formed in parallel, and the other pair of side surfaces 14b are formed in parallel with each other.
By attaching a "mold" to the ceramic powder 17 side of 8..., there is some flexibility, but the shape can be formed into a substantially rectangular cross section.

By the way, in the present invention, as shown in FIGS. 6 and 7, the heater 14, which is formed to have a substantially rectangular cross section by the above manufacturing method, is connected from the vaporization end to the combustion end 12.
The holder 16, which covers the outer circumferential surface from the outside along the longitudinal direction, is formed in a cylindrical shape such that at least its inner circumferential surface 16a separates a substantially equal booth S from the outer circumferential surface of the heater 14. In this embodiment, the holder 16 is formed to have a similar shape so as to cover the heater 14.

According to experiments and studies conducted by the inventors of the present application, the supply speed of the sprayed fuel oil, its viscosity,
From the relationship with the thickness of the fuel oil film formed on the outer circumferential surface of the heater 14, the heating temperature distribution in the longitudinal direction of the heater 14, etc., the specifics of the booth S between the outer circumferential surface of the heater 14 and the inner circumferential surface 16a of the holder 16 are determined. As a target value
The results showed that 0.2 to 2.0 mm was the most desirable.

Therefore, if the heater 14, whose shape is limited to a substantially rectangular cross section, is combined with the holder 16 formed in a similar shape so as to space the above-mentioned booth S substantially equally over the entire outer circumferential surface of the heater 14, the supply The fuel oil can be efficiently vaporized while being transferred between the vaporization end side and the combustion end 12 side, and reliable ignitability and stable combustion characteristics of the vaporized fuel at the combustion end 12 are ensured. This can contribute to improving the startability of the engine.

[Effect of idea]

According to the present invention described above, the following excellent effects are exhibited.

(1) Overcoming the disadvantage of conventional intake burners that cannot sufficiently improve engine starting performance By forming and combining the holders so that the surfaces cover the heaters at approximately equal distances, the supplied fuel can be efficiently vaporized, ensuring reliable ignition performance and stable combustion characteristics. This can contribute to improving the startability of the engine.

(2) The structure is simple and can be easily adopted.

[Brief explanation of the drawing]

Fig. 1 is a schematic plan sectional view showing the intake system of an internal combustion engine, Fig. 2 is a partially cutaway side view showing a conventional example, and Fig. 3
The figure is a partially cutaway side view showing an intake burner to which the present invention is applied, Figure 4 is a perspective view of section A in Figure 3, Figure 5 is a sectional view taken along the - line in Figure 4, and Figure 6 is a FIG. 7 is a perspective view showing a preferred embodiment of the present invention, FIG. 7 is a cross-sectional view taken along the - line in FIG. 6, and FIG. 8 is a cross-sectional view showing a molded state of a ceramic heater. In the figure, 1 is an internal combustion engine, 2 is an intake system, 14 is a heater, 14a and 14b are side parts constituting its outer peripheral surface, 16 is a holder, 16a is its inner peripheral surface, and S is a separation distance.

Claims (1)

[Scope of utility model registration request] A heater for heating intake air flowing through an intake system of an internal combustion engine while transporting fuel supplied from a fuel supply port in a longitudinal direction along its outer peripheral surface to vaporize and burn the fuel; In the intake burner, the heater is formed of a ceramic body having a substantially rectangular cross section, and the surface of the heater facing the fuel supply port is is perpendicular to this to serve as a fuel receiving surface, and the inner circumferential surface of the holder is approximately equal to the outer circumferential surface of the heater, with a booth space of 0.2 to 2.0 mm apart from the outer circumferential surface of the heater to cover this. An intake burner structure characterized in that a holder is formed in a similar shape to the heater.