JPH02298727A - Igniter plug - Google Patents

Abstract

PURPOSE:To stably perform an ignition even at a high rate of air speed by disposing a protective cover having a plurality of air holes around the ignition source in parallel with the air flowing direction so as to reduce the influence of the air speed on the ignition performance. CONSTITUTION:Since the air pressure in the protective tube 2 becomes lower that the outside air pressure in accordance with the principle of Pitot tube, the air enters from holes 3 drilled in the side of the protective tube 2. On account of the pressure loss when the air passes through the holes 3, the speed of air passing through the protective tube 2 becomes less than 1/2 of that which passes outside the igniter plug. Further, since the fuel particles injected near to the igniter plug are carried away with the incoming air through the holes 3, the ignition at the igniter plug becomes easier. The holes 3 in the side of the protective tube 2 will have the same effect if they are drilled at an angle. The protective tube 2, moreover, prevents the heat generator 1 from being damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ignition device, and particularly to an igniter plug having a structure with excellent ignition performance in high-speed airflow.

[Conventional technology]

An example of a typical conventional igniter plug structure will be described with reference to the drawings.

FIGS. 3(a) and 3(b) show an example of the structure of an igniter plug using pulsed discharge, and the electrode 10
Igniter plugs that apply a voltage of 1.000 to 2000 V between the electrode 11 and the electrode 11 to cause discharge and ignite, and which generate energy of 2 to 32 J (joules) due to discharge, are generally commercially available.

FIGS. 4(a) and 4(b) show an example of the structure of an igniter plug using a resistive heating element, in which a laminated heating element 20 made of a conductive ceramic 25 and an insulating ceramic 26 is shown. By applying a voltage of 45V or less to the electrodes and flowing a current of 10 to 15A, the laminated heating element 20
The tip of the lamp is heated to a red-hot temperature of 1,000 to 1,300°C and used as an ignition source.

FIG. 5 shows an igniter plug (3rd generation) with a capacity of 2 J that uses the conventional pulse discharge described above.
Figure 4) and an igniter plug using a resistive heating element (Figure 4) with the temperature of the heating element set at 1000°C, the flow velocity (m/s) of air passing near both igniter plugs, Time from fuel injection to ignition (
The results of investigating the relationship S) are shown below. As shown in the figure, at the same air flow velocity, there is a difference in ignition performance between the two igniter plugs, but as the air flow velocity increases, both igniter plugs tend to experience a delay in ignition. Furthermore, it is shown that when the air flow velocity is 30 to 40 m/s or more, no ignition occurs in any of the igniter plugs. Note that light oil was used as the fuel for this ignition test.

In the above-mentioned conventional igniter plug, when the allowable value of the time from fuel injection to ignition is set to 2 seconds (allowable ignition delay time) and the air flow velocity (m/s) is varied, the pulse discharge type FIGS. 6 and 7 show the results of investigating the energy required to ignite the igniter plug and the temperature required to ignite the igniter plug using a resistive heating element.

FIG. 6 is a graph showing the relationship between the energy (J) required for ignition of a pulse discharge type igniter and the air flow velocity (m/s). At an air flow velocity of 10 m/s, the energy required for ignition is approximately Although it was possible to ignite with 2 J, at an air flow velocity of 50 m/s, approximately 30 J of energy is required.

In addition, in the case of an igniter using a resistance type heating element shown in Fig. 7, the temperature required for ignition was 850°C at an air flow velocity of 10 m/s, but when the air flow velocity was 5 m/s, the temperature required for ignition was 850 °C.
At 0 m/s, a temperature of approximately 1200°C is required.

As is clear from the above results, in order to reliably ignite under high air flow rates, a pulse discharge type igniter with high generated energy or an igniter using a resistance heating element that can maintain high temperatures is required. There has been a problem in that the life of the igniter decreases proportionally as the energy increases and as the heat generation temperature increases.

[Problem to be solved by the invention]

As mentioned above, in the conventional technology, ignition is generally performed at a constant air flow velocity in many cases, so little consideration is given to the relationship between the ignition performance of the igniter plug and the air flow velocity. First, in normal cases, the air flow velocity at the exit of the ignition torch should be designed so that it does not become too high, or if the air flow velocity is high, a pulse discharge type igniter that generates high energy or one that can be maintained at a high temperature can be used. Igniters using resistance-type heating elements have been selected and used as appropriate, but as mentioned above, their lifespan is short due to harsh usage conditions.As a result, the frequency of igniter replacement has increased, and igniter repair has become more and more difficult. There were problems of increased costs and complicated maintenance.The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional technology, reduce the influence of air flow velocity on the ignition performance of the igniter, and reduce the influence of air flow velocity on the ignition performance of the igniter, even under high air flow velocity. An object of the present invention is to provide an igniter plug having a structure that allows easy ignition and convenient use.

[Means to solve the problem]

The object of the present invention is, for example, in a discharge-type igniter plug using pulse discharge or an electric resistance-type igniter plug using a resistance-type heating element, the air flow that contacts the ignition source part of the igniter plug is slowed down. like,
This can be achieved by providing an igniter plug with a cylindrical airflow-buffering protective cover that is parallel to the airflow direction and has a plurality of ventilation holes around the ignition source.

The present invention provides an electric resistance type igniter plug that uses a resistance type heating element as the ignition source of the igniter and performs ignition operation by energizing the heating element and heating it to a high temperature. The electrical resistance type igniter plug is constructed with a protective cover having a plurality of vent holes for semi-isolating the ignition source from high-speed airflow flowing through the ignition source and forming a low-speed airflow region around the ignition source.

The present invention also provides a discharge-type igniter plug that is used as an ignition source for an igniter and performs ignition by applying a voltage between electrodes and discharging the igniter. The discharge type igniter plug is constructed with a protective cover having a plurality of vents to isolate and create a low-velocity airflow region around the ignition source.

In the igniter plug of the present invention, it is preferable that the protective cover provided in the igniter plug and having a plurality of ventilation holes has a shape that surrounds the ignition source of the igniter plug in a cylindrical shape. The cylindrical protective cover provided on the igniter plug has a plurality of ventilation holes, and the opening diameter at the tip of the protective cover is D, the diameter of the ventilation hole provided on the side surface of the cylindrical protective cover is d, and the ventilation hole is When the number of N is N, it is more preferable that the relationship satisfies NXd2.

[Effect]

By semi-isolating the ignition source of the igniter plug (e.g., the discharge part in a pulse discharge igniter, or the red-hot part in an igniter using a resistive heating element) from the high-velocity airflow flowing around the igniter plug, The igniter plug 1 can secure the air flow velocity range, makes it extremely easy to ignite the igniter, and does not require the energy generated in the ignition source or the temperature of the ignition source to be abnormally high during the ignition operation. Stable ignition is obtained over a long period of time, and its life is significantly improved.

〔Example〕

An embodiment of the present invention will be described below in more detail using one drawing.

FIG. 1 is a sectional view showing an example of the structure of an igniter plug using the resistance type heating element of the present invention.

In the figure, the igniter plug is composed of a heating element 1, an electrode joint 5, and a protective tube 2, and has a structure in which when electricity is applied between screws 6 and 8, current flows through the heating element 1 and generates heat. The protective tube 2 has a cylindrical shape, and a large number of holes 3 are provided in the cylinder.

Figure 2 shows the distribution of air flow velocity at the tip of the protection tube when the igniter plug shown in Figure 1 is installed in a high-speed air flow. Since the air pressure inside the protection tube 2 is lower than that outside due to the Pitot tube principle, air flows into the protection tube 2 through the hole 3 provided on the side surface thereof. The air flow rate inside the protection tube 2 is never faster than the air flow rate passing through the outside of the protection tube 2 because a pressure loss occurs when the air passes through the holes 3. The hole diameter d provided on the side of the protection tube 2 is relative to the opening diameter of the tip of the protection tube 2.
If the relationship between the number of holes and the number of holes N is ``4Nxd'', the air flow rate passing through the protective tube 2 is 1/1/1 of the air flow rate passing outside the igniter plug due to the pressure loss passing through the holes 3. 2 or less.

Further, when the air flows into the hole 3, particles of fuel sprayed near the igniter plug are carried along with the air, so that the igniter can be ignited more easily.

Although the hole 3 provided on the side surface of the protective tube 2 is perpendicular to the side surface in this embodiment, it has been confirmed that the same effect as described above can be obtained even if the hole 3 is provided diagonally.

Furthermore, compared to the igniter plug using a resistive heating element according to the prior art shown in FIG. 4, the igniter plug of the present invention shown in FIG. Another feature is that the protection tube 2 can prevent the heating element 1 from breaking.

〔Effect of the invention〕

As explained in detail above, even when the igniter plug of the present invention is installed in a high-speed air flow, the ignition source part of the igniter (in the case of a pulse discharge type igniter plug, the discharge part, and the igniter using a resistive heating element) The red-hot part of the heating element in the plug can be set to a low air flow velocity compared to the air flow velocity outside the igniter plug, ensuring stable ignition at all times and significantly extending the service life of the igniter plug. can be extended to

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the structure of an electrical resistance type igniter plug illustrated in an embodiment of the present invention. Figure 2 is a schematic diagram showing the air flow velocity distribution at the tip of the protective tube of the igniter plug shown in Figure 1, Figure 3 (a)
is a cross-sectional view showing the structure of a conventional pulse discharge type igniter plug, Fig. 3 (b) is a view taken in the direction of arrow A in Fig. 3 (,), and Fig. 4 (,) is a cross-sectional view showing the structure of a conventional pulse discharge type igniter plug. A cross-sectional view showing the structure of the igniter plug, FIG. 4(b) is B of FIG. 4(a).
Fig. 5 is a graph showing the test results of the ignition performance of a conventional pulse discharge type igniter and an igniter using a resistive heating element. Fig. 6 is a graph showing the energy required for ignition of a conventional pulse discharge type igniter. FIG. 7 is a graph showing the relationship between the temperature required to ignite an igniter using a conventional resistance type heating element and the air flow speed. 1... Heating element 2... Protection tube 3... Hole
4... Sealing glass 5... Electrode joint part
6... Screw 7... Insulator 8... Screw 10... Electrode 11... Electrode 12...
・Gap 13...Semiconductor 14...Glass powder 15...Insulator 16...Screw
17...Screw 18...Insulator 20...
Laminated heating element 21... Metal protection tube 22... Screw 23... Insulator 24... Screw 25...
Conductive Ceramics 26... Insulating Ceramics Agent Patent Attorney Junnosuke Nakamura 3 --- One Hole 7 --- Seishu 114 ---
--t↑Stopper 8----hL" Fig. 1 2==: Fig. 2 (a) to-m-electrode 11-continuation 12--W*Iv1 (b) 'th 3 Figure 20-111o 11th; (t5f!: I book 21--
-- Money, lll protection! The tube 22 --- one' Fig. 4 Pulse wL Mr. `` 8 < m / S ) Fig. 5 Empty Ta L Ubijt ( m / sl Fig. 6 Air Uke 'tJ- (m/s) Light figure 7

Claims (1)

[Scope of Claims] 1. An electric resistance type igniter plug that uses a resistance type heating element as the ignition source of the igniter, and in which the heating element is energized and heated to a high temperature to perform the ignition operation. , an electrical resistance type igniter comprising a protective cover having a plurality of ventilation holes semi-isolated from the high-speed airflow flowing around the igniter plug and forming a low-speed airflow region around the ignition source. plug. 2. In a discharge-type igniter plug that performs ignition operation by applying a voltage between electrodes and discharging the igniter as an ignition source, the ignition source of the igniter is semi-isolated from the high-speed airflow flowing around the igniter plug, A discharge type igniter plug, further comprising a protective cover having a plurality of ventilation holes for forming a low-velocity airflow region around the ignition source. 3. In the igniter plug according to claim 1 or 2, the protective cover having a plurality of ventilation holes provided in the igniter plug has a shape that surrounds the ignition source of the igniter plug in a cylindrical shape. An igniter plug characterized by being a protective cover. 4. In the igniter plug according to any one of claims 1 to 3, the cylindrical protective cover provided on the igniter plug and having a plurality of ventilation holes has an opening diameter of D at the tip of the protective cover. , the diameter of the ventilation holes provided on the side of the cylindrical protective cover is d, and the number of ventilation holes is N.
An igniter plug characterized by having a relationship that approximately satisfies D^2≒N×d^2.