JPH02234034A - Temperature detector - Google Patents

Abstract

PURPOSE:To improve reliability by utilizing the change in an output signal which is outputted from a temperature detecting terminal on the basis of the difference of temperature characteristics between a 1st and a 2nd detecting elements and obtaining a detected temperature as the boundary temperature of the 2nd detecting element. CONSTITUTION:A PTC thermistor 4 has the positive temperature characteristic in a fixed temperature range. And a V type thermistor 6, where a specified temperature To in the fixed temperature range is regarded as the boundary, has the positive temperature characteristic on a high temperature side corresponding to the thermistor 4, and has the negative temperature characteristic on the side where the temperature is lower than the temperature To. Such a temperature detector 1 is arranged, for example, near the heat generating part of an air conditioning equipment and a prescribed voltage Vcc is supplied between lead wires 7a and 7b. In the temperature range where the temperature of the thermistor 4 or 6 is higher than the temperature To, the ratio between the impedance of the thermistor 6 and the whole impedance of the thermistor 4 or 6 is always fixed. Contrarily, in the temperature range where the temperature of the thermistor 4 or 6 is lower than the temperature To, the ratio is rapidly increased on the basis of the negative temperature characteristic of the thermistor 6. Thus, the temperature control for the air conditioning equipment can be performed by detecting the output signal V01.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a temperature detector, and more specifically, to temperature detectors for heat generating objects such as air conditioners and internal combustion engines. This invention relates to a temperature detector useful for temperature control and temperature abnormality detection.

(Prior Art) Conventionally, as this type of temperature detection device, one shown in FIG. 6 is known.

The temperature detection device 30 shown in the same figure includes a PTC thermistor Tk and a resistor R, which are connected in series as a detection element whose resistance-temperature characteristics (hereinafter referred to as "temperature characteristics") are positive and linear in a certain temperature range. The connection point between the two is connected to one terminal of the comparator 31.

The other terminal of the comparator 31 is connected to a resistor R. ,R, are connected.

When a predetermined voltage Vcc is supplied from the power supply to the temperature detection device 30, the comparator 31 is supplied with a voltage corresponding to the change in the ambient temperature of the PTC thermistor Th and a reference voltage from the resistors R2 and R3. An output signal (voltage) vo corresponding to the change in the ambient temperature is obtained from the output terminal of the sensor, and desired temperature detection can be performed.

However, in the temperature detection device 30 described above,
In addition to the PTC thermistor Th, circuit elements such as the comparator 31 and resistors R and R are essential, and the number of components increases.
In addition to raising the price and lowering the reliability of the device itself, this also increases the size of the entire device, which poses problems in terms of mountability in the target equipment.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to provide a temperature detector that can be lowered in price, improved in reliability, and also has excellent mounting performance. It is something to do.

[Configuration of the Invention (Means for Solving the Problems) The temperature sensor of the present invention has the following features over a constant temperature range:
a first detection element having a positive temperature characteristic; a second detection element having a positive temperature characteristic corresponding to the first detection element in a high temperature side region of the temperature range; and a second detection element having a positive temperature characteristic in a low temperature side region; The sensor is configured by connecting the first and second sensing elements in series and using the connection point of the first and second sensing elements as a temperature detection terminal, and outputs from the temperature sensing terminal based on the difference in temperature characteristics of both the sensing elements. The detected temperature as the boundary temperature of the second detecting element is determined using the change in the output signal.

(for production) The operation of the temperature detector having the above configuration will be explained below.

When the temperature characteristics of the first and second detection elements change due to a change in ambient temperature, the temperature detection terminal detects the temperature at a certain temperature based on the difference in the temperature characteristics of both the detection elements, i.e., An output signal is output that suddenly changes at a boundary temperature where the characteristic of the second detection element changes from negative to positive. Therefore, the temperature at which the output signal suddenly changes can be specified as the detected temperature.

(Example) Examples of the present invention will be described below with reference to FIGS. 1 to 4.

The temperature sensor 1 shown in FIG. 1 includes a disk-shaped substrate 2 having insulating properties, and a first detection element disposed on the upper surface 2a of the substrate 2, which is a chip type and has electrode portions 3a and 3b. a PTC thermistor 4 as a second detection element (details will be described later) 6, which is also a chip type and has electrode parts 5a and 5b, and is also disposed on the upper surface part 2a.
Lead wires 7a, 7b, 7c attached to the substrate 2 and a lid 8 attached to cover the upper surface 2a of the substrate 2.
It is equipped with.

The upper end portion of the lead wire 7a passes through the substrate 2 to the upper surface portion 2.
a, and one electrode portion 3a of the PTC thermistor 4 is connected to this upper end.

The upper end of the lead wire 7b passes through the substrate 2 and is exposed on the upper surface 2a, and the -type thermistor 6 is connected to this upper end.
One electrode portion 5a of the two electrodes is connected to each other.

Further, the upper end portion of the lead wire 7C penetrates the substrate 2 and is exposed on the upper surface portion 2a, and the both thermistors 4 are connected to the upper end portion of the lead wire 7C.
, 6 are commonly connected.

An equivalent circuit of the temperature detector 1 is shown in FIG.

As is clear from this equivalent circuit, the PTC' thermistor 4 and the V-type thermistor 6 are connected in series through the electrode portions 3b and 5b. The lead wire 7a is used as a power supply terminal for supplying a predetermined voltage Vcc, the lead wire 7b is used as a ground terminal, and the electrode portion 3
b,. The lead wires 7C connected to the terminals 5b are respectively made to function as temperature detection terminals.

Here, the temperature characteristics of the PTC thermistor 4 and the V-type thermistor 6 will be explained with reference to FIGS. 3(a) and 3(b).

The PTC thermistor 4, as shown in FIG. 3(a),
It has a positive temperature characteristic in which the value of impedance Z1 increases as the temperature rises within a certain temperature range.

On the other hand, as shown in FIG. 3(b), the V-type thermistor 6 operates at a specific temperature (boundary temperature) within a certain temperature range.
It has the same positive temperature characteristic as the PTC thermistor 4 or the same ratio as the PTC thermistor 4 in which the value of impedance Z2 increases on the high temperature side with T0 as the boundary, and also has a specific temperature T. Impi on the lower temperature side? It has a negative temperature characteristic in which the value of dance Z2 decreases.

A specific example of such a V-type thermistor 6 is BaT.
One example is a TiOx system in which barium Ba in an iO3-based PTC is replaced with strontium S and lead P, which have the same valence and approximate ionic radius (SrPb) (Electro Ceramic X: 1988 May 5) Monthly issue: “
(See “V-type characteristic PTC material”).

Next, the operation of the temperature detector 1 having the above structure will be explained with reference to FIG. 4 as well.

This temperature detector 1 is placed near the heat generating part of an air conditioner, for example, and the lead wire is used. A predetermined voltage ycc is supplied between a and 7b.

The temperatures of the PTC thermistor 4 and the V-type thermistor 6 are the specific temperature T. In a temperature range higher than , the ratio Z2/(Z■
+2. ) is always constant, and conversely, the temperature of both thermistors 4.6 is the specified temperature T. In a temperature range lower than , the ratio Z2/(zt +z2') increases rapidly based on the negative temperature characteristic of the V-type thermistor 6.

Therefore, at this time, the relationship of the following equation {1} holds true.

? ...(11 And from the relationship of this equation (11), the temperature detection terminal 7
The output signal (voltage) Vos from c is at a specific temperature T as shown in FIG. After that, it decreases rapidly.

Therefore, this output signal V. By detecting (2), the temperature of the heat generating part of the air conditioner to be detected by the temperature detector 1 can be specified, and the temperature of the air conditioner can be controlled.

According to the temperature detector 1 described in detail above, temperature can be detected simply by using the first and second detection elements having the above-mentioned temperature characteristics, so the cost can be reduced by reducing the number of parts. Reliability is improved, and furthermore, since it can be made smaller, high-density mounting in air conditioning equipment and the like is also possible.

? Next, another example of the embodiment of the present invention will be explained with reference to FIG.

The temperature detector IA shown in the figure is different from the one shown in FIG. 2 in that the lead wire 7b is used as a power supply terminal and the lead wire 7a is used as a ground terminal.

In the case of this temperature detector IA, the temperature of both thermistors 4.6 is the specific temperature T. PT in the temperature range higher than
Ratio of impedance z1 of C thermistor 4 to overall impedance (Z1+22) 2■/ (21 +22)
is constant, and conversely, in a temperature range lower than the specific temperature T0, the ratio Z1/(Zl +22) increases rapidly. Therefore, in this case, the following (2)
The formula holds true.

...(2) From the relationship of this equation (2), the temperature detection terminal 7
The output signal V from c. 2 becomes as shown in Figure 4,
As in the case described above, the temperature of a heat generating part of an air conditioner or the like can be specified.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

[Effects of the Invention] According to the present invention detailed above, the first detection element having a positive temperature characteristic in a certain temperature range and the second detection element having a ■-shaped temperature characteristic are used. As a result, it is possible to provide a temperature detector that can significantly reduce the number of parts compared to conventional devices, lower the cost, improve reliability, and also improve mountability.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view of an embodiment of the present invention, Fig. 2 is a circuit diagram of the embodiment, and Fig. 3(a) is a PT in the embodiment.
FIG. 3(b) is a temperature characteristic diagram of the type C thermistor in the same embodiment. FIG. 4 is a temperature characteristic diagram of the output signal of the device shown in the same embodiment and FIG. 5. The figure is a circuit diagram showing another example of the embodiment of the present invention, and FIG. 6 is a circuit diagram of a conventional device. 1, IA...Temperature detector, 4...PTC thermistor, 6...V type thermistor. To = (T) 1 (T) (a) (b) Figure 3 Figure 4 Figure 1 Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] A first detection element having positive temperature characteristics over a certain temperature range, a positive temperature characteristic corresponding to the first detection element in the high temperature region of the temperature range, and a negative temperature characteristic in the low temperature region. A second detecting element having a characteristic is connected in series, and a connection point between the first and second detecting elements is a temperature detecting terminal. A temperature detector characterized in that a detected temperature as a boundary temperature of the second detection element is determined by utilizing a change in an output signal output from a temperature detection terminal.