JPH0228452Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air blow detection device that combines a temperature switch composed of a temperature-sensitive magnetic material, a reed switch, and a permanent magnet, and a heater element.

This type of airflow detection device is mainly used for detecting abnormal stoppage of cooling fans of power equipment and the like. However, conventional heaters have used a normal resistor as a heater element, and when the fan stops abnormally, the temperature of the resistor heating element rises abnormally, posing a problem in terms of safety.
Furthermore, since the heater element is exposed in the air detection area, there is a risk of electric shock or short circuit caused by an external object.

The purpose of the present invention is to solve the above problems by using a positive temperature coefficient thermistor with a self-temperature holding function as a heater element, and to provide an air blowing detection device that ensures thermal safety when the fan stops abnormally. do.

The present invention also aims to provide an air detection device that is easy to assemble, inexpensive, and highly safe.

The present invention includes a temperature switch composed of a temperature-sensitive magnetic material, a reed switch, and a permanent magnet, a heater element that heats the temperature-sensitive magnetic material, and a rectangular insulating main frame and auxiliary frame that hold them. In the air blow detection device, the heater element is a positive temperature coefficient thermistor having a self-temperature holding function;
and a second electrode plate having spring properties installed on the frame so as to sandwich the thermistor between the first electrode plate, and the main frame and the auxiliary frame have It is characterized in that a protective grid is provided to prevent contact between an external object and the heater element.

Examples of the present invention will be described below.

FIG. 1 is an external view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof.

This device has two legs of a U-shaped temperature-sensitive magnetic body 4.
A temperature switch in which two permanent magnets 5 and 5' are fitted around the outer periphery of a reed switch 7 with magnetic poles aligned in the axial direction and with a spacer 6 made of a gap or a non-magnetic material, and a temperature switch with positive characteristics. A heater element consisting of a thermistor 3, a first electrode plate 1 to which a power source is connected, and a square-shaped second electrode plate 2, and a rectangular insulating main frame 9 for holding these elements.
It consists of an auxiliary frame body 10 made of the same material.

In the temperature switch, the open end of the temperature-sensitive magnetic body 4 is fitted into grooves 91 and 91' provided in the main frame body 9,
Leads 71, 71' of the reed switch 7 and terminals 8, 8' welded to the lead ends 71, 71' are fitted into grooves 92, 92' provided in the main frame 9 and held therein. One end of the electrode plate 1 is fitted into a groove 93' provided in the inner wall of the main frame 9, and the other end serves as a lead wire connection terminal 83 and is fitted into the groove 93 provided in the main frame 9. That is, this electrode plate 1 is
It is installed so as to be in close contact with the outer surface of the closed end side of the temperature-sensitive magnetic body 4 of the temperature switch held in the main frame 9 to hold the temperature switch. Also, electrode plate 2
One end of the electrode plate 1 on the same side as the lead wire connection terminal 83 is fitted into a groove 94 provided on the inner wall of the main frame body 9, and the other end is used as the lead wire connection terminal 81 and provided on the main frame body 9. The groove 94' is fitted into the groove 94'. The electrode plate 2 is installed on the main frame 9 with the positive temperature coefficient thermistor 3 sandwiched between the trapezoidal upper side and the electrode plate 1. The positive temperature coefficient thermistor 3 includes projecting pieces 21 and 2 formed by folding back and cutting up the electrode plate 2.
1' and the projecting pieces 22, 22' prevent displacement in the surface direction. An auxiliary frame 10 is fixed to the main frame 9 by adhesive or welding to prevent the temperature switch and heater element from falling off. Reference numerals 95 and 95 are mounting pieces for the main body of the device.

This device is installed in a ventilation path using mounting pieces 95, 95' so that air can pass through the main frame 9,
A power source is connected to electrode plate 1 and electrode plate 2. As a result, the positive temperature coefficient thermistor 3 generates heat, but
When air is blown at the rated wind speed, heat is dissipated by the air flow, so the temperature of the closed end 41 of the temperature-sensitive magnetic body 4 is suppressed below its Curie point, and the entire temperature-sensitive magnetic body 4 exhibits ferromagnetism. ing. Therefore, most of the magnetic flux from the permanent magnets 5, 5' flows through the temperature-sensitive magnetic body 4, and only a small amount of magnetic flux flows through the contact portion of the reed switch 7, so that the reed switch 7 is in an open state.

When the peripheral speed becomes lower than the rated wind speed from this state, the temperature of the positive temperature coefficient thermistor 3 increases because the heat dissipation due to the air flow decreases. Following this, the temperature of the electrode plate 1 and the closed end side 41 of the temperature-sensitive magnetic body 4 also rises, and when the temperature of the closed end portion 41 reaches the Curie temperature Tc,
Becomes paramagnetic. Due to this, the permanent magnet 5,
Most of the magnetic flux from 5' flows into the reeds of reed switch 7, causing the contacts to close, and an electrical circuit connected to terminals 8 and 8' detects a decrease in air flow. On the other hand, the positive temperature coefficient thermistor is stably maintained at a predetermined constant temperature above the Curie temperature Tc by its self-temperature holding function, so compared to the conventional air blowing detection device that uses a resistor heating element as the heater element, the air blowing stops. Thermal safety is improved.

Incidentally, AC 100 to 230 V is normally applied to the electrode plates 1 and 2 as the heater power supply voltage.
If a metal-based material is used as the temperature-sensitive magnetic body 4 to shorten the response time, the entire temperature-sensitive magnetic body 4 will have the same potential as the electrode plate 1, and external objects such as parts housed in a metal case, hands, fingers, etc. It is extremely dangerous if touched.

For this reason, in the present invention, protective grids 96 and 101 are provided in the wind passing parts of the main frame 9 and the auxiliary frame 10 so as not to obstruct the ventilation, so that external objects do not touch the current-carrying parts of the respective elements. It is integrated. As for the method of installing these, integral molding is preferable. Of course, it is provided on the side of the main frame 9 opposite to the joint surface with the auxiliary frame 10.

3 and 4 show other examples of the main frame 9 and the auxiliary frame 10, respectively.

In the extending direction of the electrode plate, there are two protective grids 9 whose thickness is minimized so as not to increase ventilation resistance.
6' (FIG. 3) and 101' (FIG. 4) are provided at predetermined intervals (according to safety standards).

The sixth line in FIG. 5 shows still another example of the main frame 9 and the auxiliary frame 10.

In either example, the lattice of the main frame body 9 is provided outside the bottom of the deep groove so as not to interfere with the arrangement of each element.

FIG. 7 is a diagram showing the installed state of the device of the present invention.

The auxiliary frame body 10 is installed so as to face the blades of the air cooling fan 12. In this case, even if the protective grid of the auxiliary frame 10 is omitted, there is no problem with safety.

As described above, the air blow detection device according to the present invention is
In order to arrange the heater element on the outer surface of the closed end side of the approximately U-shaped temperature-sensitive magnetic body through the first electrode plate, a trapezoidal second electrode plate having spring properties is used to ensure adhesion. By increasing the height, the heat generated by the heater element can be efficiently transmitted to the temperature-sensitive magnetic body, and the response when the air flow rate decreases can be improved. In addition, by using a thermistor with a self-temperature maintenance function as a heater element and providing a protective grid on the main frame,
Can prevent abnormal heat generation, electric shock, short circuits, etc.
It is possible to provide an air blow detection device that is easier and cheaper to assemble than conventional ones, and which operates with high integrity and stability.

[Brief explanation of drawings]

Figure 1 is an external view of an embodiment of the airflow detection device according to the present invention, Figure 2 is an exploded perspective view of Figure 1, and Figure 3 is an exploded perspective view of Figure 1.
5 and 5 respectively show other examples of the main frame, FIGS. 4 and 6 show other examples of the auxiliary frame, and FIG. 7 shows the device of the present invention. A diagram showing an installation example. In the figure, 1, 2; electrode plate; 3; positive temperature coefficient thermistor; 4; temperature-sensitive magnetic material; 5, 5'; permanent magnet; 7;
Reed switch, 9; main frame body, 10; auxiliary frame body,
12: Air cooling fan.

Claims (1)

[Scope of utility model registration request] A temperature switch is a reed switch in which two permanent magnets are fitted around the outer periphery of a reed switch with magnetic poles aligned in the axial direction and spaced apart from each other at a constant distance, and installed between the legs of a generally U-shaped temperature-sensitive magnetic body. , an air blowing detection device comprising a heater element that heats the temperature-sensitive magnetic material, and a rectangular insulating main frame and an auxiliary frame that hold the heater element; the heater element includes a positive temperature coefficient thermistor; A first electrode plate is installed on the frame so as to be in close contact with the outer surface of the closed end side of the magnetic body, and a spring is installed on the frame so as to sandwich the thermistor between the first electrode plate. and a second trapezoidal electrode plate having a trapezoidal shape, and a protective grid is provided on at least the main frame of the main frame and the auxiliary frame.