JPS6153606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric ignition device that increases discharge energy and significantly improves ignitability.

This type of piezoelectric ignition device consists of a pair of polarized columnar piezoelectric elements whose positive electrode surfaces face each other and come into contact with each other through a terminal plate, and a needle provided at the tip of an insulated wire connected to the terminal plate. The positive discharge electrode is electrically connected to the negative electrode surfaces at both ends of a pair of piezoelectric elements, and a needle-shaped negative discharge electrode is connected to a part of a grounded metal case or protrudes from the metal case. The output is increased by electrically connecting a pair of piezoelectric elements in parallel, and by grounding the discharge electrode on the negative side through a metal case. Although the ignition performance is generally satisfactory for general combustion equipment such as gas burners, it has become easier to ignite under all kinds of severe conditions or for small ignition devices such as ignition devices of cigarette lighters. There is a demand for high ignitability that can sufficiently handle even when

The present invention has been made to satisfy the above-mentioned needs, and as shown in FIG. The electrode 11 is formed into a plate shape and is grounded, while the negative electrode side 1
The discharge surface of the negative spark discharge electrode 12 connected to the lead wires drawn out from b and 1b, which faces the positive spark discharge electrode 11, is shaped like an arc to form a discharge gap G. be.

FIG. 2 shows a specific example of this, and 1 and 1 are a pair of piezoelectric elements made of a lead zirconate titanate compound, etc., each having electrode surfaces (not shown) formed by baking silver on both end faces and polarized. In an insulating case 3 equipped with a terminal plate 2 having needle-like terminal legs 2a protruding outward, mechanically in series and electrically in parallel,
In the present invention, contrary to the conventional method, the negative electrode surfaces of the two terminals are connected to each other, facing each other, and the positive electrode surfaces of the two electrodes are housed as the outer ends. 4 and 5 each have their outer ends protruding outward from the insulating case 3, and their inner ends abut against the positive electrode surfaces of the piezoelectric elements 1, 1 via cushioning materials 6, 6 made of thin sheets of soft metal. , a pressurizer and a stator 7 made of metal that transmit external force to the piezoelectric elements 1, 1 seat a stator 5 protruding from the side end of the insulating case 3 on one end surface 7a, and a similarly insulating plate on the other end. The pressurizer 4 protrudes from the other side end of the case 3 and the pressurizer 4 is connected to the energy storage spring 9.
A metal case is provided with a striking element 8 that is subjected to an impact by the striking element 8 and an impact means (not shown) that engages with the striking element 8 and biases the storage spring 9 and then explodes to impact the striking element 8. The metal case 7 is insulated from the negative electrode surfaces of the piezoelectric elements 1, 1 by the insulating case 3, and is also a fixed metal case 7 that is in contact with the positive electrode surface of one of the outer ends of the piezoelectric elements 1, 1. The metal case 7 is electrically connected and grounded through the pressurizer 4 and the striker 8 that are in contact with the stator 5 and the other positive electrode side, and extends from one end surface 7a of the metal case 7 on which the stator 5 is seated. an insulated electric wire connected to a plate-shaped positive electrode discharge electrode 11 and a terminal leg 2a protruding from the side wall of an insulating case 3 and protruding from a terminal plate 2 that comes into contact with the negative electrode surface of the piezoelectric elements 1, 1. A spark gap G is formed by the negative electrode side spark discharge electrode 12 which is provided at the tip of the electrode 10 and has an arcuate discharge surface. In this example, a solid cylindrical body is used for the positive discharge electrode 12, but a hollow cylindrical body or one formed into a cylindrical coil shape from a metal wire as shown in FIG. Any type of coil may be used; in particular, the use of the latter cylindrical coil makes it easy to connect to the end of the insulated wire by extending one end in a straight line, and it also allows the raw gas to be injected from the burner nozzle toward the spark gap G. This is advantageous in that the unevenness of the large number of winding portions causes disturbance and improves the mixing state with air.

Example A pair of columnar piezoelectric ceramics 1, 1 made of a lead zirconate titanate compound and having a piezoelectric constant _g33 of 28 x ^{10 -3} Vm/N and measuring 5 mmφ x 10 ml were mechanically assembled as shown in Fig. 2A. A metal case 7 with a U-shaped cross section is made of a steel plate and is electrically connected in series and electrically in parallel within the insulating case 3, and is electrically connected to the positive electrode surfaces at both outer ends of the pair of piezoelectric elements. As shown in FIG. 2C, a spark discharge electrode 11 on the positive electrode side with a width of 10 mm and a length of 20 mm extended from one end surface of the grounded electrode, and an insulated wire 10 connected to the terminal plate 2 on the inner end surface on the negative electrode side, as shown in FIG. 1
A piano wire of 0.6 mmφ is wound at a pitch of 2.5 mm to a total length of 25 mm in the spark discharge gap G formed by the positive electrode 12, which is a coil-shaped positive electrode 12 made by winding a stainless steel wire of mmφ with an outer diameter of 6 mmφ and a length of 20 mm. Rotated spring constant 80
g/mm is compressed to 15 mm by a 90 g impactor 8, and then is rapidly rebound to impact the pressurizer 4 to show the relationship between the spark discharge intermittent G and the discharge energy induced at that time. As before, the positive side electrode surfaces of the piezoelectric element were faced and brought into contact, and the positive side spark discharge electrode extended from this was insulated as a 1 mmφ needle.
The spark discharge electrodes on the negative side at both outer ends were plate-shaped and grounded, and the needle-like electrode on the positive side was opposed at right angles to the plate-shaped electrode on the negative side, but the conditions were exactly the same. Figure 3 shows the average values of the results of each 50 experiments.

However, the discharge energy was measured using the measurement circuit shown in FIG. In the figure, P is a piezoelectric material according to the present invention, R is a resistance of 10Ω, and A ₁ is an attenuation ratio of 1/1000.
A ₂ is a probe with a damping ratio of 1/10, and S is a web form calculator (SM-1300) made by Iwasaki Tsushinki.

As shown in FIG. 3, the spark discharge energy induced by the spark discharge electrode of the present invention shows a clear difference from that by the conventional spark discharge electrode, and is actually quite large at the normally set discharge gap of 4 mm. The value was more than twice as high.

Next, the two types of piezoelectric igniters were fixed at a position where the front end of the spark discharge electrode was 10 mm away from the tip of a gas tube with an inner diameter of 3 mmφ and a primary air hole of 3 mmφ, and methane gas, which had poor ignitability, was passed from the gas tube. was ejected at a pressure of 250 mm of water column, and 50 mm each under the same conditions as before.
After performing several spark discharges and measuring the ignition rate,
As shown in FIG. 4, the piezoelectric ignition device using the discharge gap of the present invention has a spark discharge gap of 3 mm,
%, when the spark discharge gap was 4 mm, the ignition rate was 94%, whereas the piezoelectric ignition device using a conventional discharge electrode had an ignition rate of 0% at a spark discharge gap of 3 mm, and only a slight ignition rate when the spark discharge gap was 4 mm.
The discharge energy was only 30%, which was less than 1/3 of that of the present invention, and the result was similar to the discharge energy shown in FIG.

As described above, the discharge electrode of the present invention has the remarkable effect of greatly increasing the discharge energy compared to conventional discharge electrodes, and thereby significantly increasing the ignition rate. Even if the ignition device is made smaller, it still shows sufficient ignitability, so it is particularly effective for use in cigarette lighters that require smaller size.
It has great effects such as being able to fit into the small space of combustion equipment such as gas burners.

In the present invention, even if the negative electrode side discharge electrode drawn out and insulated from the negative electrode side of the piezoelectric element shown in the above embodiment is changed from a coil shape to a cylindrical shape, the same effect as that of the coil is obtained, and the discharge electrode The polarity is also opposite to that shown in Figures 1 and 2, with the positive side electrode surfaces of the pair of piezoelectric elements facing each other, and the positive side discharge electrode provided at the tip of the lead wire drawn out from the opposing surfaces as a flat plate. A metal case may be insulated and connected to the negative electrode surfaces at both ends of the pair of piezoelectric elements, and the negative discharge electrode extending from the metal case may be in a coil shape. It is also possible to use only one piezoelectric element without connecting them mechanically in series and electrically in parallel.

[Brief explanation of the drawing]

FIG. 1A is a schematic diagram showing the basic circuit device of the present invention, FIG. Figure B is a cross-sectional view of the discharge electrode along the Ro-Ro line in Figure A, Figure C is a cross-sectional view of another discharge electrode corresponding to Figure B, and Figure 3 is a cross-sectional view of the discharge electrode according to the present invention. A diagram comparing the discharge energy with respect to the discharge gap between the spark discharge electrode and the conventional spark discharge electrode, and FIG. 4 compares the ignition rate with respect to the discharge gap between the spark discharge electrode of the present invention and the conventional spark discharge electrode. Diagram shown in Figure 5
The figure is a circuit diagram for measuring spark discharge energy. 1... Column piezoelectric element, 11... Positive electrode side (ground)
Spark discharge electrode, 12... Negative electrode side (insulated) spark discharge electrode, G... Spark gap.

Claims (1)

[Claims] 1. A pair of spark discharge electrodes that are electrically connected to both the positive and negative electrode surfaces of a columnar piezoelectric element are arranged to face each other in close proximity to a burner of a combustion device, in which the positive spark discharge electrode is grounded in the form of a plate; A piezoelectric ignition device characterized in that a discharge surface of a negative spark discharge electrode facing the positive spark discharge electrode is formed in an arc shape.