JPS626498Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature detection device that utilizes a plurality of temperature switches having mutually different operating temperatures, each of which is a combination of a reed switch, a permanent magnet, and a temperature-sensitive magnetic material.

The configuration of this type of temperature switch is shown in Figures 1 and 2.
As shown in the figure.

The temperature switch shown in FIG. 1 has a reed switch 1 fitted with an annular temperature-sensitive magnetic material 2 having a predetermined Kyrie point so as to face its contact portion, and an annular permanent magnet on both sides of the temperature-sensitive magnetic material 2. 3.3 is fitted. In the temperature detection operation, while the temperature of the temperature-sensitive magnetic material 2 is lower than its Curie point, the reed switch 1 is in a closed state by forming a closed magnetic path passing through its contact portion, and when the temperature exceeds the Curie point, the reed switch 1 is in a closed state. The body 2 exhibits paramagnetism and the reed switch 1 opens and opens, which is a so-called normally closed type.

On the other hand, the temperature switch shown in FIG. 2 has an annular paramagnetic material 4 interposed between the two annular temperature-sensitive magnetic materials 2, 2, so that the temperature switch shown in FIG. It is a normally open type in which the reed switch 1 is closed when the temperature of the reed switch 2 exceeds its Curie point.

All of these devices can perform desired temperature detection by selecting the Curie point of the temperature-sensitive magnetic material 2, and are used in many industrial fields because they are small, highly reliable, and inexpensive.

By the way, when trying to detect multiple levels of temperature using such a temperature switch, it is necessary to install a temperature switch equipped with a temperature-sensitive magnetic material that has a Curie point corresponding to each detected temperature on the temperature-detected part. The required number of lead wires are drawn out from each temperature switch to directly take out the detection signal, or a changeover switch is inserted and connected to obtain the detection signal only from the desired temperature switch.

An object of the present invention is to enable selection of a desired detection temperature without using a changeover switch when temperature detection is performed using a plurality of temperature switches having different operating temperatures.

The temperature detection device according to the present invention connects a resistor in series to each of a plurality of temperature switches having different operating temperatures, and connects each of these series connected circuits in parallel to a single resistor to form a parallel circuit, Furthermore, a variable resistor is connected in series to the parallel circuit, and a semiconductor switching element is connected so as to be turned on and off by the voltage divided by the parallel circuit and the variable resistor, and by adjusting the variable resistor. A feature is that the detected temperature can be arbitrarily selected.

Examples of the present invention will be described below.

FIG. 3 shows a circuit diagram of an embodiment of the temperature detection device according to the present invention.

In the figure, 13 and 14 are a temperature-controlled load and an AC power source, which are connected to a temperature detection device via a relay RL. TS ₁ , TS ₂ , TS ₃ are load 1
A normally open type _temperature switch having _{the structure} shown _in FIG _. T ₃ ). These temperature switches TS ₁ , TS ₂ ,
Resistors 5, 6, and 7 with resistance values R ₁ , R ₂ , and R ₃ are connected in series to TS ₃ , and then connected in parallel with a resistor 9 with resistance value R ₄ to form a parallel circuit 1.
2 is constructed, and is connected to a DC power supply V _DC and a ground terminal via a variable resistor 8 connected in series with this parallel circuit 12 . Furthermore, the collector terminal of transistor Q is connected to DC power supply V _DC via relay RL.
, the emitter terminal is connected to the ground terminal of the parallel circuit 12,
A base terminal is connected to a connection point 10 between the parallel circuit 12 and the variable resistor 8.

Now, _let R' 1 be the sum of the contact resistance of the contact portion when the temperature switch TS ₁ is in the closed state and the resistance value R ₁ of the resistor 5. Resistance value R ₂ of temperature switch TS ₂ and resistor 6, resistance value of temperature switch TS ₃ and resistor 7
Similarly, for R ₃ , the total value in the closed state is
Let R′ ₂ and R′ ₃ . Also, the combined resistance of parallel circuit 12 is
R ₀ (=1/1/R' ₁ +1/R' ₂ +1/R' ₃ +1/
R' ₄ ), the voltage between terminals 10 and 11 of the parallel circuit 12 is represented by _Vi , the DC power supply voltage is represented by _Vp , and the resistance value of the variable resistor 8 is represented by _Vi = R _p /R _p +RV ₀ . Indicated by (1).

Since the temperature switches TS ₁ , TS ₂ , and TS ₃ are of the normally open type, as the temperature rises, the combined resistance value R _p of the parallel circuit 12 changes stepwise as shown in FIG. That is, until the temperature T ₁ is reached, R _p1 =
1/1/R ₄ = R ₄ , and since the temperature switch TS ₁ is closed when the temperature is between T ₁ and T ₂ , R _p1 = 1/1/R' ₁ + 1/
Within the temperature range of R′ ₄ , T ₂ and T ₃ , R _p2 =
1/1/R' ₁ + 1/R' ₂ + 1/R' ₄ , and since all temperature switches TS ₁ to TS ₃ are closed when the temperature is T ₃ or higher, R _p3 = 1/1/R ' ₁ +1/R' ₂ +1/R' ₃
+1/ _R'4 . Therefore, the voltage V _i between the terminals of the parallel circuit 12 also changes as the temperature rises and depending on the resistance value of the variable resistor 8.

For example, R′ ₁ = 12kΩ, R′ ₂ = 6kΩ, R′ ₃ = 2kΩ,
If R ₄ = 4KΩ, R _pp = 4kΩ, R _p1 = 3kΩ, R
_p2 = 2kΩ, R _p3 = 1kΩ, and in this case V _i
The relationship between the resistance value of the variable resistor 8 and the resistance value of the variable resistor 8 is shown in the fifth
It will look like the figure.

Now, if the voltage V _ON to be added to the base of transistor Q in order to flow the current necessary to operate relay RL is 0.4V ₀ , then in Fig. 5, the solid line V _O
In the upper region of _N , the contacts of the relay RL are in a closed state, and the AC power supply 14 is energized to the load 13, and in the lower region, the contacts of the relay RL are in an open state. Therefore _, by setting the resistance value of the variable resistor ₈ within _the respective ranges shown in FIG. be able to.

For example, a variable resistor 8
When the resistance value is set, when the temperature of the detected part is less than _T1 , the voltage V _i between the terminals 10 and 11 is greater than V _ON , so the contact of the relay RL is closed. When the temperature exceeds T ₁ , the temperature switch TS ₁ operates (closes) and the voltage V _i changes from a value on the curve R _pp to a value on the curve R _{p 1} and smaller than V _ON as shown by the arrow. The contacts of relay RL open. The temperature rises further and reaches T ₂ and T ₃ , and the temperature switch is activated.
Even if TS ₂ and TS ₃ operate, voltage V _i is lower than V _ON and the contacts of relay RL remain open. Conversely, when the temperature decreases from a high temperature to less than temperature _T1 and temperature switch _TS1 returns (opens), the contact of relay RL changes to the closed state.

Next, set the resistance value of variable resistor 8 to the median value of the range.
When set to 3.8 kΩ, when the temperature reaches T ₁ and the temperature switch TS ₁ is closed, the voltage V _i changes from on the curve R _pp to on the R _{p 1} as shown by the dashed arrow, but V _O
Since it is larger than _N , the contact of relay RL remains closed, and when the temperature reaches T ₂ and temperature switch TS ₂ closes, V _i changes to become less than V _ON as shown by the arrow, and the relay The RL contact opens.

Similarly, by setting the resistance value to the median value of the range, 2.3 kΩ, the operation of the temperature switch TS ₃ at the temperature T ₃ can be reflected in the operation of the relay RL to detect the temperature T ₃ .

As described above, the temperature detection device of the present invention can obtain the opening/closing signal of any one of a plurality of temperature switches having different operating temperatures by adjusting the resistance value of the variable resistor. .

Although the embodiment has been described using a normally open temperature switch, it is clear that selective temperature detection can be similarly performed using a normally closed temperature switch. However, in this case, a relay with a make contact will be used. Further, various changes such as using a semiconductor switching element in place of relay RL are possible, and the present invention is not limited to the embodiment.

[Brief explanation of the drawing]

1 and 2 respectively show a normally closed type temperature switch and a normally open type temperature switch used in the present invention;
The figure is a circuit diagram of one embodiment of the temperature detection device according to the present invention, Figure 4 is a diagram showing the relationship between the combined resistance of the parallel circuit in Figure 3 and temperature, and Figure 5 is the resistance value of the variable resistor. FIG. 2 is a diagram showing the relationship between V i and transistor input voltage V _i . 1...Reed switch, 2...Temperature-sensitive magnetic material, 3
...Permanent magnet, 4...Paramagnetic material, TS ₁ , TS ₂ ,
TS ₃ ...Temperature switch, 8...Variable resistor, RL
...Relay, 13...Load, 14...AC power supply.

Claims (1)

[Scope of utility model registration request] A resistor is connected in series to each of a plurality of temperature switches having mutually different operating temperatures, each of which is a combination of a reed switch, a permanent magnet, and a temperature-sensitive magnetic material, and each of these series-connected circuits is connected in parallel to a single resistor. to form a parallel circuit, further connecting a variable resistor in series to the parallel circuit, and connecting a semiconductor switching element so as to be turned on and off by a voltage divided by the parallel circuit and the variable resistor, A temperature detection device characterized in that the detected temperature can be arbitrarily selected by adjusting the variable resistor.