JPH02251012A - Ignition device using ceramic heater - Google Patents

Abstract

PURPOSE:To raise the durability of a ceramic heater by closing the rear end of a cylindrical body made of a heat resistant material which has a notch for gas flow-in formed from the end opening towards the rear end with a ceramic heater which has an electric resistor buried in a ceramic insulation body and at the same time inserting the heater until its tip end reaches the notch. CONSTITUTION:The rear end of a cylindrical body 2 made of a heat resistant material which forms a notch 22 for gas flow-in from the end opening 23 towards the rear end is closed with a ceramic heater 1 which has an electric resistor 33 buried in the ceramic insulation body 32 and at the same time the heater 1 is inserted so as to make the tip end of the heater 1 reach the notch 22. When this ceramic heater 1 is made to generate heat by electrification and a fuel gas is sent from the notch 22 for gas flow-in, ignition occurs near the notch 22 for gas flow-in. This ignition flame is carried to the opening at the tip end of the cylindrical body made of a heat resistant material by the pressure of the fuel gas. That is, the flow channel of the fuel gas is not likely to be subject to heat loss due to air blast, etc., because it is for the most part covered by the cylindrical body 2 made of a heat resistant material, and it is heated efficiently by the ceramic heater 1. The fuel gas that passes through the gas flow channel is ignited thereby at a low temperature.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ignition device that does not generate noise '1E waves in the case of fuel gas, and is particularly suitable for igniting difficult-to-ignite fuel (natural scum). Regarding the ignition device.

[Prior Art] A discharge device is known that causes a liquid fuel such as petroleum (vaporized) or a gas such as methane sludge to undergo spark discharge. However, since noise radio waves were generated during discharge, it was necessary to provide strict shielding to prevent interference with the electronic control circuits of combustion appliances equipped with this master device and the electronic circuits in nearby rooms.

Therefore, in recent years, ignition devices using ceramic heaters that do not generate noise radio waves have been attracting attention.

The ceramic heater used in this ignition device is manufactured by embedding an electric resistor in a ceramic insulator.

[Problem to be solved by the invention] Normally, when igniting city gas, mainly natural gas, the surface temperature of the ceramic heater is set to
It is necessary to heat the temperature to 00℃ or higher (12℃ in actual use)
10°C or higher). Therefore, if heating and cooling are repeated, even a ceramic heater using a silicon nitride-based ceramic insulator has a drawback that its durable life is short.

An object of the present invention is to provide an ignition device that can reliably ignite difficult-to-ignite fuel gas even if the ignition temperature is reduced, thereby improving the durability of a ceramic heater.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cylindrical body made of a heat-resistant material, which has a cylindrical shape and has a gas inflow notch formed from the tip opening toward the rear end. A ceramic heater in which an electric resistor is embedded in a ceramic insulator is used to close the rear end of the cylindrical body, and is fitted so that the tip of the navigation heater reaches the notch.The heater is energized to generate heat, and the gas A configuration was adopted in which fuel gas is sent in through a notch for inflow and ignited.

[Operation and Effects of the Invention 1 The ignition device using a ceramic heater has a cylindrical shape and has an electrical resistor attached to a cylindrical body made of a heat-resistant material with a gas inflow notch formed from the tip opening toward the rear end. A ceramic heater embedded in a ceramic insulator closes the rear end of the cylindrical body and is fitted so that the tip of the heater reaches the notch.

When this ceramic heater is energized to generate heat and fuel gas is fed through the gas inflow notch, ignition occurs near the gas inflow notch. This ignition flame is carried by the pressure of the fuel gas to the opening at the tip of the cylindrical body made of a heat-resistant material.

That is, since the gas flow path of the fuel gas is mostly surrounded by a cylindrical body made of a heat-resistant material, it is hardly affected by heat loss due to wind cooling, and can be efficiently heated by the ceramic heater. Therefore, the fuel gas passing through the gas flow path has a lower flame temperature than when there is no cylinder made of heat-resistant material. Furthermore, since the ignition temperature can be reduced, the heat generation temperature of the ceramic heater can be lowered, and the durability of the heater can be improved.

[Example] Next, the present invention will be described based on a first example shown in FIGS. 1 to 4.

The ignition device A shown in FIG. 1 is used for igniting methane gas, and is made up of a ceramic heater 1 and an outer cylinder 2 fitted therein. This igniter A is attached near the main burner 100 of a gas cooker (not shown).

In the ceramic heater 1, the rear end (not shown) of the heater body 3 is embedded in an insulator 4 (cylindrical), and the tip 31 protrudes from the tip surface 41 of the insulator 4. Heater body 3
is a ceramic sintered body (flat plate) mainly composed of silicon nitride.
32, a molybdenum wire 33 is buried in a substantially W-shape.

Both ends of this molybdenum wire 33 are connected to the rear end surface 42 of the insulator 4.
It is energized by lead wires 11, 12 taken out from. Note that the dimensions of the tip 31 (protruding portion) of the heater main body 3 are 4 mm in width, 2 mm in thickness, and 33 mm in length.

The outer cylinder 2 is formed of a ceramic sintered body mainly composed of silicon nitride, and the rear end 21 has a slightly larger diameter and is fitted into the tip 43 of the insulator 4. This outer cylinder 2 largely surrounds the tip 31 of the heater main body 3. Further, a gas inflow notch 22 is formed from the tip end [123] toward the rear end 21.

An opening 52 of a gas jet pipe 51 is arranged to face this gas inflow notch 22 . In addition, each dimension (shown in FIG. 3) is as follows. The tip 24 of the outer cylinder 2 is
The length is 38 mm and the inner diameter i = 6 mm. The gas inflow notch 22 has a width j=4 mm, and a length 1 from the tip opening 23 to the end 25 of the notch 22 is 18 mm. The distance 1lik between the tip portion 34 of the heater main body 3 and the tip opening 23 is 5 mm.

<Regarding the surface temperature of the starter to ensure ignition> Ignition device 9
As shown in FIG. 2, when 99% pure methane gas (200 mmAq) 5 was introduced from the gas inflow notch 22, the heater surface temperature at the tip 31 of the heater body 3 rose to 1060°C or higher. It was found that ignition was possible with certainty.

Comparative product D is the one with outer cylinder 2 removed from this ignition device A.
(shown in FIG. 7), and when similarly measured, it was found that the surface temperature needed to be 1100° C. or higher.

<About durability test> The ceramic heater 1 draws a durability life curve as shown in FIG. Here, the horizontal axis is the Table 1-01 temperature of the tip 31 when the heater main body 3 is energized for 1 minute, and the vertical axis is the 1-minute energization and the next 1-minute energization J1 as one cycle. This is the number of cycles until the end of life.

In actual use, the heater 1 is used in an overload range of about 10%, so the surface temperatures of the ignition device A and the comparative product during use are considered to be 1166° C. and 11210° C., respectively. In other words, the durability of the ignition device A can be improved by about three times from the life curve shown in FIG. 4.

FIG. 5 shows an ignition bag JR which is a second embodiment of the present invention.

In the ignition device B, the length of the tip 24 of the outer cylinder 2 is shortened, and the distance l (between the tip surface 34 and the tip opening 23) is Omm.

Also, the length ρ from the tip opening 23 to the end 25 of the notch 22
is 6 mm. Other dimensions, materials, etc. are the same to the igniter.

In ignition device B, the reliably reliable heater surface temperature is 1070°C (10% overload temperature) 177°C. The durability of the igniter B is about 3 times better than the comparative crystal by a little over 1 turn.

FIG. 6 shows a ignition bag WC according to a third embodiment of the present invention.

The ignition bag HHc extends from the distal end surface 1] 23 to the end 25 of the notch 22.
The length β of the trowel is 30 mm. Other dimensions, materials, etc. are the same as igniter A.

The reliably reliable heater surface temperature in the ignition bag WC is 1060°C (10% overload temperature 1166°C). The durability of igniter C is about 3 times better than that of the comparative crystal.

Next, the clearance m between the corner 35 of the heater body 3 and the inner wall 26 of the outer cylinder 2, and the distance between the tip opening 23 of the outer cylinder 2 and the tip surface 34 of the heater body 3, as shown in FIGS. 8 to 10. IJI
k, the width j of the gas inflow notch 22, and the tip opening 23
The appropriate range of the length ρ from to the end 25 of the notch 22 will be described.

The appropriate clearance m is in the range of 0.5 mm to 2.0 T1111. If it is less than 0.5 mm, methane gas5
If it exceeds 2.0111111, the heat generation efficiency will deteriorate.

The appropriate distance is within the range of O (mm) to 2 i (TIIIT+).
If the heater body 3 protrudes from the tip opening 23, the ignition flame 6 (see FIG. 2) jetting out from the tip opening 23 is obstructed, and the flame 6 causes the protruding portion of the heater body 3 to become excessively heated. Moreover, if it exceeds 2i (mm), heat loss increases.

The width j is (1/3) i (mm) ~ i (In
ITI > range or appropriate. (1/3)i (m
m), the inflow of methane gas 5 is poor, and i(mm
), the reduction in ignition temperature is poor.

The appropriate length ρ is in the range of i (mm) to 5j (mm). If it is less than 1, it will be poor in quality, and if it exceeds 5j, it will be poor in suppressing wind cooling on the surface of the heater.

The present invention includes embodiments other than the above embodiments.

a. In the above example, the ignition device used methane gas, but liquids (oil gas, oil scum, coal gas,
C is also suitable for ignition of gaseous fuels such as aqueous scum and blast furnace scum.

1) The shape of the electrically insulating ceramic insulator may be a square bar shape or a round bar shape.

C. As the material of the ceramic insulator and the heat-resistant cylinder, other ceramics such as alumina, mullite, and silicon carbide may be used. Further, the cylinder made of heat-resistant material may be made of heat-resistant metal such as stainless steel or nickel alloy.

d. In addition, tungsten, tantalum, alloys thereof, conductive ceramics, etc. may be used for the electric resistor.

e. Ceramic insulators may be manufactured by laminating clean sheets, and electrical resistors may be manufactured by applying conductive paste.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the ignition device according to the first embodiment of the present invention; FIG. 2 is an explanatory diagram illustrating the ignition principle of the ignition device; and FIG. 3 is a partial cross-sectional view of the ignition device. FIG. 4 is a graph showing the relationship between the heater surface temperature and the durability life curve of a ceramic heater. FIG. 5 is a partial sectional view showing an ignition device according to a second embodiment of the invention, and FIG. 6 is a partial sectional view showing an ignition device according to a third embodiment of the invention. FIG. 7 is a side view of a comparative product. FIG. 8, FIG. 9, and FIG. 10 are explanatory diagrams for explaining appropriate dimensions of each part. In the diagram: 1...Ceramic heater 2...Outer tube (tube made of heat-resistant material) 3...Heater body 4...Insulator (insulator) 5...Methane gas (fuel gas) 21...Back End 22...Notch for gas inflow 23...Tip opening
31... Tip 32... Ceramic sintered body (ceramic insulator) 33... Molybdenum, m (electrical resistor) A, B, C... Ignition device

Claims (1)

[Scope of Claims] 1) A ceramic cylinder having a cylindrical shape and having a notch for gas inflow formed from the tip opening toward the rear end, and an electric resistor embedded in a ceramic insulator. A heater is used to close the rear end of the cylindrical body and is fitted so that the tip of the heater reaches the notch, and the heater is energized to generate heat and fuel gas is sent through the gas inflow notch to ignite the ceramic. Ignition device using a heater.