JP2015141057A - flame detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a reliable light shielding function at a flame detector, even if a light shielding mechanism is small.SOLUTION: A flame detector includes: a convex lens positioned in front of a flame light receiving part; a shutter provided in the vicinity of a focus of light converged by going through the lens for blocking entrance of light; a flame detection sensor for detecting the light; and a solenoid coil for moving the shutter by magnetic force and retreating it from the light path. Instead of the convex lens, a concave mirror having a paraboloid shape may be used.

Description

  The present invention relates to a light shielding mechanism of a flame detector that is used for monitoring a flame of a combustion apparatus and detects light from the flame.

A discharge tube (hereinafter referred to as “tube”) is used to monitor the flame of the burner in the combustion apparatus. The tube is a discharge tube configured such that a discharge is generated between electrodes when ultraviolet light or other light emitted from a flame enters.

In the prior art, it is necessary to detect whether the actual flame or the self-discharge of the tube at an early stage, and Patent Document 1 has been invented for the purpose of providing a tube failure detection device.
In the tube failure detection apparatus according to the present invention, a shutter for blocking the incident light of the tube is provided, and the rate of change of the tube output is measured when the shutter is shut off. Hesitated to give a warning signal. Thus, the shutter is important for the flame detector.

JP-A-5-012581

  In the prior art, the more light entering the flame detector, the easier it is to detect the flame. However, if the light receiving part of the flame detector is increased, the light shielding mechanism must be increased.

  In order to solve this problem, the present invention realizes a light blocking mechanism that can block a large amount of light even if the shutter is small by converging light by a lens or the like and providing a light blocking mechanism at a position where the optical path is narrowed. .

The present invention is a flame detection sensor for detecting light emitted from a flame,
A lens positioned between the flame and the flame sensor;
A shutter that blocks the incidence of light converged through this lens;
A diaphragm for limiting a range in which light can pass on the light path;
A drive unit that moves the shutter between a closed position and an open position that is a position where the amount of light blocking the incidence on the flame detection sensor is smaller than the closed position;
It is a flame detector characterized by providing.

Furthermore, the present invention provides a light path,
A lens moving mechanism for moving the position of the lens;
Or a diaphragm moving mechanism for moving the position of the diaphragm;
Furthermore, the present invention is a flame detection device that adjusts the amount of light shielding by combining with a shutter moving mechanism that moves the position of the shutter.

  Further, as another light converging mechanism, a flame detector is characterized in that a parabolic (parabolic) concave mirror is used and a shutter for blocking light incidence is provided at the focal point of the parabola.

  Due to constraints such as product size and temperature conditions, the force to open and close the shutter may be insufficient. The light-shielding mechanism according to the present invention shields the collected light so that the light can be sufficiently shielded even if the stroke is small, and this function is improved.

The position and size of the shielding mechanism that is the principle of the present invention will be shown. The flame sensor unit sectional drawing which is an embodiment of this invention is shown. The electric circuit structure for implementation of this invention is shown. The flame sensor unit sectional drawing which is an application aspect of implementation of this invention is shown. Sectional drawing of the flame sensor unit using the concave mirror which is another aspect of implementation of this invention is shown.

[Principle of the Invention]
First, a description will be given based on the principle of the present invention. First, the flame detection sensor 1 is a so-called tube in which a pair of discharge electrodes that receive light to cause discharge are enclosed in a cylindrical glass tube, and lead terminals of the discharge electrodes are led out from one end of the glass tube. is there. The shutter 2 is formed by a blade made of a long spring body. The blade is magnetically attracted to displace the blade, and is composed of a movable mechanism including a solenoid coil or the like that moves (withdraws) from the front surface of the distal end portion of the tube. The lens 5 is a convex lens.

In FIG. Shows the conventional configuration. Thus, in order to shield the parallel light of light in front of the sensor 1, a considerably large shutter 2 is necessary.
On the other hand, B. In the present invention, incident light is converged by the convex lens 5 and reaches the sensor 1. If a shielding mechanism is provided near the focal point of this optical path, the shutter can be made small.
B. The left figure shows the “open position”, B.I. The right side shows the “closed position”, which is the principle of the present invention.

(1) Mechanical structure FIG. 2 is a sectional view illustrating a light shielding mechanism in a flame detector as one embodiment of the present invention. In general, a viewing window such as a gas burner (
A flange unit 20 attached to the flange unit 20, a unit holder 30 attached to the flange unit 20, and the unit holder 30.
A shutter unit 40 incorporated in the lower part of the camera. The flame detection unit 10 is detachably mounted on the upper surface of the unit holder 30, and the unit holder 30 and the shutter unit 40 are collectively covered with a synthetic resin cover 50 having a higher light shielding property.

The lens 5 is provided on the optical path where the flame light inside the flange unit 20 enters. The flame light converged by the lens 5 gathers at the focal position of the lens, and further diffuses and reaches the flame detection unit 10. A diaphragm 6 is provided for limiting the range in which light can pass on the light path. The diaphragm 6 is also for shielding sneak light other than regular incoming light.

The shutter unit 40 includes a flame detection unit 10 attached to the unit holder 30.
The shutter blade 41 is provided opposite to the front end portion (light receiving window) and blocks the incidence of light on the flame detection unit 10.
And a drive mechanism comprising a solenoid coil 42 of the shutter blade 41.
Incidentally, the shutter blade 41 is made of, for example, stainless steel (
SUS) made of a long leaf spring body, and the tip portion bent into an L shape is the flame detection unit 10.
It is installed in the vicinity of the focal point of the light converged from the lens, and its rear end portion (root portion) is fixed. Even if the displacement stroke of the tip is small, it is sufficiently secured. The shutter blade 41
A solenoid coil (driving mechanism) 42 that is bent to be displaced and driven is a hollow core formed by winding a coil conductor in a rectangular shape, and is energized and driven at a predetermined cycle by a shutter control unit (not shown).

Now, due to the magnetic force generated by the energization of the solenoid coil 42, the metal piece 41c attached downward to the front end side of the shutter blade 41 is drawn into the air core portion of the solenoid coil 42, whereby the shutter blade 41 is bent downward against its elastic force. Then L of the shutter blade 41
The tip end bent in a letter shape is withdrawn from the position near the focal point on the optical path converged by the lens, and the incoming flame light (light) enters the tube accommodated in the flame detection unit 10 to cause the flame. Detection is performed. This is the “open position” where the amount of light blocking the incidence on the flame detection sensor is small.

Thereafter, when the energization of the solenoid coil 42 is stopped, the shutter blade 41 returns to its original state by its elastic return force, and L
The tip end bent in a letter shape is positioned again on the front surface of the flame detection unit 10 and returns to the state of blocking the incidence of light on the flame detection unit 10. This is the “closed position”, and the feature of the present invention is that the stroke of the open / close state transition can be small.

(2) Electric circuit Next, with reference to FIG. 3, an electric circuit for carrying out the present invention will be described.
In this case, the flame sensor (unit) 3 has a light receiving portion of the burner 300.
The sensor 1 is a tube disposed opposite to the sensor 1, the shutter 2 is movably provided on the front surface of the light receiving unit of the sensor 1, and the solenoid coil 42 moves the shutter 2. Such a flame sensor 3 constitutes a flame detector together with an external circuit 200 that controls its operation. This external circuit 200
Are an AC power source 201 that applies a voltage between the discharge electrodes of the sensor 1 and a flame detection unit 202 that detects the presence or absence of flame in the burner 300 based on the discharge current flowing from the sensor 1.
And a shutter control unit 203 for supplying a coil current to the solenoid coil 103 based on the detection result by the flame detection unit 202.

Here, in the flame sensor 100, the shutter 2 is initially closed. At this time, the shutter 2 is closed by being pulled by the pulling force of the spring as shown in the drawing.
Next, in order to open the shutter 2, the flame detection unit 202 instructs the shutter control unit 203 to pass a current from the shutter control unit 203 to the solenoid coil 42. As a result, since the shutter 2 is retracted from the location and the light passes (open state), if a flame is generated in the burner 300, the light emitted from the flame is irradiated to the light receiving portion of the sensor 1 through the lens. , Discharge current flows.

The shutter opening is determined by the balance between the pulling force due to the coil current and the reaction force due to the spring. The flame detection unit 202 is designed so that the coil current can be appropriately changed. Specifically, the voltage value of the power supply voltage 204 provided to the shutter control unit 203 is determined as appropriate. That is, in this embodiment, the electric power (product of the power supply voltage 204 and the coil current) related to the opening / closing operation of the shutter 2 in the flame sensor unit 3 can be smaller than the conventional one in the flame sensor unit 3. It is.

(3) Other Examples FIG. 4 shows an example of an adjustment mechanism for adjusting the optical path and the light amount in order to enhance the light shielding effect, as another example of the present invention.
The lens 5 is mounted on the front surface of the flange unit 20 and slides the lens 5 itself on the optical path. The lens position may be slid by rotating the attachment 21 at the front of the flange unit 20 with a screw. By doing so, the focal position of the convergent light can be changed, and the lens moving mechanism can adjust the shutter effect.

  Furthermore, the amount of light that has passed through the lens 5 can also be reduced by the diaphragm 6 provided between the lens 5 and the shutter blade 41. The position of the diaphragm 6 can be realized by intermittent adjustment by changing the mounting position, for example, by continuous adjustment using a screw or a solenoid. By providing this mechanism, it is the diaphragm moving mechanism that enables sensitivity adjustment.

In addition, the position of the shutter 41 can be directly adjusted, and a shutter moving mechanism that mechanically adjusts the shutter unit 40 in the holder 30 with a screw 60 or the like may be provided.

(4) Another embodiment As another light converging mechanism, a concave mirror having a parabolic shape is used, and a shutter for blocking light incidence is provided at the focal point of the parabola. It is an example of the flame detector to do. Since the parallel light incident due to the parabolic shape can be condensed at the focal position of the parabola, an equivalent function can be realized by using a mirror instead of the lens in the above example if a shutter is provided near the focal point.

An example is shown in FIG. A parabolic concave mirror 8 with a sharpened tip is provided inside the flange unit 20. In this way, the shutter blade 41 is positioned near the focal point of the light that has passed through the cut portion. The characteristics of the light shielding mechanism are the same as in the above-described embodiment.
Also in this embodiment, a lens equivalent to the stop 6 may be provided before or after the concave mirror as in the first embodiment, and the effect is also common. However, illustration is omitted.

  In addition, although it demonstrated in common with the above this Example with the tension | pulling spring, it is the same also by employ | adopting a pushing spring conversely. Other various design matters can be changed and improved, but they remain within the scope of the present invention.

1 Sensor (tube)
2 Shutter
3 Flame sensor unit 5 Lens 6 Aperture 8 Concave mirror 10 Flame detection unit 20 Flange unit 21 Attachment 30 Unit holder 40 Shutter unit 41 Shutter blade 41c Metal piece 42 Solenoid coil 50 Cover 60 Adjustment screw 200 External circuit 201 AC power supply 202 Flame detection unit 203 Shutter control unit 204 Drive power source 300 Burner

Claims (5)

A flame detection sensor for detecting light emitted from the flame;
A lens positioned between the flame and the flame sensor;
A shutter that blocks the incidence of light converged through this lens;
A diaphragm for limiting a range in which light can pass on the light path;
A drive unit that moves the shutter between a closed position and an open position that is a position where the amount of light blocking the incidence on the flame detection sensor is smaller than the closed position;
A flame detector comprising: The flame detection apparatus according to claim 1, further comprising a lens moving mechanism that moves a position of the lens on a path of the light. The flame detection device according to claim 1, further comprising: a diaphragm moving mechanism that moves a position of the diaphragm on a path of the light. The flame detection apparatus according to claim 3, further comprising a shutter moving mechanism that moves a position of the shutter on a path of the light. A flame detection sensor for detecting light emitted from the flame;
A parabolic concave mirror positioned between the flame and the flame sensor;
A shutter that is provided in the vicinity of the focal point of light converged by reflecting the concave mirror,
A drive unit that moves the shutter between a closed position and an open position that is a position where the amount of light blocking the incidence on the flame detection sensor is smaller than the closed position;
A flame detector comprising:

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