JPH0144941Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a control device used for combustion equipment for gas, kerosene, etc., and uses a flame detection rod (flame rod) to detect the presence or absence of a flame to rectify the flame. This invention relates to a high voltage absorbing device in a high impedance input circuit that detects whether a flame current is flowing.

In the present invention, in a control device for a combustion device, it is desirable to set the discharge gap as narrow as possible for the purpose of absorbing the high voltage when abnormal discharge occurs in the discharge electrode portion of the electric spark ignition mechanism. On the other hand, in order to improve the characteristics of a high impedance input circuit, it is necessary to set the discharge gap as wide as possible in order to maintain high insulation resistance.

As a solution to these two contradictory conditions, the present invention is designed to minimize the effects of the insulation resistance (including deterioration of insulation due to moisture absorption) of the printed circuit board material by punching out rectangular holes in the printed circuit board. This helps prevent high voltage from flowing into the control section of the high-impedance input circuit from the circuit, and also provides a discharge gap between the high-impedance input circuit and ground to absorb high voltage, and prevents high voltage from flowing into the flame detection rod. Even if the high voltage flows in, the energy is consumed in the air gap, completely preventing the high voltage from flowing into the control section of the high impedance input circuit, and protecting the electronic components in the control section of the high impedance input circuit from being destroyed. It is configured as follows.

[Conventional technology]

As shown in Fig. 2, this kind of conventional technology connects a gas-filled arrester 4 between a copper foil 2 of a high impedance input circuit and a copper foil 3 of a ground on a printed circuit board 1 to provide protection against abnormal voltage. There are some, but they have the disadvantage of being expensive.

In addition, as shown in Figure 3, parts such as the gas-filled arrester 4 are omitted by taking a measure to maintain a predetermined creepage distance between the copper foils on the back side of the printed circuit board 1 for the purpose of absorbing high voltage against lightning surges. However, with this method, as mentioned above, since it is a high impedance input circuit, it is necessary to apply the usual technique of applying an organic material solution (insulating varnish, etc.) to the back side of the printed circuit board 1. Therefore, there was a drawback that the discharge voltage for a given creepage distance became unstable due to the influence of the thickness of the coating film.

Generally, a flame detection circuit that detects the presence or absence of a flame has a very high impedance. This is because the rectified current of the flame is very weak, usually 0.2 μA ~
The signal is about 10μA, and the resistance of the equivalent circuit of the flame is about 1MΩ to several hundred MΩ. For this reason, as mentioned above, we are taking measures to improve the printed circuit board by using highly insulating materials.

In addition, in cases where the pattern circuits must be close to each other, a rectangular shape is placed on the printed circuit board 1 in order to minimize the effect of insulation resistance between the copper foil 2 of the high impedance input circuit and the copper foil 3 of the ground. It is known to provide the hole 9 by punching or the like.

[Problem that the invention attempts to solve]

This invention is suitable for cases where the distance between the flame detection rod 5 and the discharge electrode 6 of the electric spark ignition mechanism (igniter) IG is not set to the specified dimension value due to an operation error (setting error, installation error), or when the burner is During the spark discharge, the high voltage flows into the flame detection rod 5 due to mischievous wind, etc., and is transmitted through the copper foil 2 of the high impedance input circuit connected to the flame detection rod 5. The purpose of this invention is to prevent the control circuit from being destroyed by the high voltage (generally 16 KV) generated from the electric spark ignition mechanism IG that is added to the control circuit (not shown) for fuel supply, etc.

[Means for solving problems]

The present invention consists of a copper foil 2 of a high impedance input circuit connected to a flame detection rod 5 and a copper foil 3 of its ground.
A discharge gap T for absorbing high voltage is provided in between to discharge at a voltage sufficiently lower than the voltage output from the electric spark ignition mechanism IG for burner ignition.

〔Example〕

In the present invention, when an abnormal high voltage flows into the flame detection circuit as shown in FIG. This is constructed by utilizing bent portions 7' and 8' formed by inserting the lead wire 8 into the through hole of the printed circuit board 1.

In this case, since the distance between the copper foils on the back side of the printed circuit board 1 becomes narrow because it also serves as the electrical connection of circuit components, a rectangular hole 9 as shown in FIG. It is desirable to take measures to minimize insulation deterioration between the two.

In addition, as shown in FIG. 5, by providing high voltage absorbing discharge electrodes P1 and P2 facing each other between the copper foil 2 of the high impedance input circuit and the grounding copper foil 3, an appropriate high voltage discharge gap can be created. T can be easily obtained. In this way, the creepage distance between the copper foil 2 of the high impedance input circuit and the copper foil 3 of the ground can be sufficiently large on the printed circuit board 1, so that the rectangular hole 9 shown in FIG.
It becomes unnecessary to provide

[Effect]

Next, the operation of the present invention will be explained based on FIG. 6. Normally, the discharge electrode 6 of the electric spark ignition mechanism IG
and the flame detection rod 5 are configured to have a sufficient interval so that the discharge of the electric spark ignition mechanism IG does not flow through the flame detection rod 5 to the control circuit section of the flame detection circuit, and the discharge of the ignition device The current flows as in loop A and the flame detection current flows as in loop B.

However, due to operational errors and mischievous wind,
When the discharge of the electric spark ignition mechanism IG flows from the discharge electrode 6 to the flame detection rod 5, a loop C circuit is formed by the discharge gap T and is released to the ground copper foil 3, thereby forming a flame detection circuit section. This prevents damage to the electronic components by preventing high voltage from being applied to the electronic components in the control section of the high impedance input circuit.

〔effect〕

As explained above in detail, the present invention provides a discharge gap for high voltage absorption between the high impedance input circuit and the ground, so that the high discharge voltage generated from the electric spark ignition mechanism flows into the flame detection rod. However, by flowing into the control circuit electrically connected to this, the discharge voltage can be absorbed by the discharge gap so as not to destroy the electronic components of the circuit controlled by the low voltage. Since this objective is achieved without using other parts such as an arrester, it has the advantage of being able to be manufactured at low cost.

[Brief explanation of the drawing]

FIG. 1 shows a high voltage absorbing device according to an embodiment of the present invention, and FIGS. 2 and 3 show conventional high voltage absorbing devices. 4 and 5 show a high voltage absorbing device according to another embodiment of the present invention, and FIG. 6 shows an operation diagram of the present invention. 1 is a printed circuit board, 2 is a high impedance input circuit copper foil, 3 is a grounding copper foil, 5 is a flame detection rod,
6 is a discharge electrode, 7 is a resistor, 7' is a resistor bending part,
8 is a lead wire, 8' is a bent part of the lead wire, 9 is a rectangular hole, IG is an electric spark ignition mechanism, T is a discharge gap, and P1 and P2 are discharge electrodes for high voltage absorption.

Claims (1)

[Claims for Utility Model Registration] 1. An air gap that discharges at a voltage sufficiently lower than the voltage of an electric spark ignition mechanism used in the ignition and flame detection mechanism of a combustion control device is connected to a high impedance input circuit connected to a flame detection rod. A high voltage absorbing device characterized by being provided between the ground and the ground. 2. A utility model characterized in that the discharge gap is configured such that the bent portion formed by the jumper wire connected to the ground and the lead wire of the electrical component constituting the high impedance circuit is opposed to each other. A high voltage absorbing device according to claim 1. 3. The high voltage absorbing device according to claim 1 of the utility model registration, characterized in that the discharge portion is provided on the surface of a printed circuit board.