JPH0511782B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sensor that detects state quantities Q such as temperature and gas concentration.

The sensor of the present invention is a sensor that can quickly detect temporal changes (dQ/dt, etc.) in the state quantity Q, and is used, for example, in fire prevention equipment, gas leak alarms, etc.

[Prior Art] Conventionally, sensors have been provided that detect state quantities Q such as the temperature and gas concentration of a target to be detected as electrical signals E and provide them as control data for temperature control devices, fire prevention equipment, gas leak warning devices, etc. has been done.

In the above, if data regarding temporal changes in the state quantity Q (dQ/dt, etc.) is required,
The detected signal is processed by software using a microcomputer or by hardware using a differential circuit or the like to obtain data regarding the required temporal change.

[Problems to be Solved by the Invention] As described above, data regarding the rate of change over time of the state quantity Q is required as control data for temperature control devices, fire prevention equipment, gas leak warning devices, etc. Ru.

For example, if we consider fire prevention equipment as an example,
It is too late to activate the alarm once the fire temperature T _f has been reached. For this reason, in the past, focusing on the fact that the temperature increase rate V _f = dT/dt that leads to a fire outbreak is more rapid than the normal temperature increase pattern, the detected temperature data T (state quantity Q) was calculated using a differential circuit. The required data regarding the rate of change over time has been obtained by processing the data using hardware such as the above or software using a microcomputer.

However, processing using the above-mentioned microcomputers or hardware circuits is not only expensive, but also has problems such as reduced reliability due to circuit complexity, environmental resistance problems of circuit components, and worsened installation ease due to larger equipment. bring points.

In addition, as in the case of temperature control, if switching the control of operating parts such as air conditioners after reaching the set upper limit (and lower limit) temperature does not pose a particular problem in terms of safety, the microcomputer or No processing using hardware circuits was performed, and the detection data was used as is for control.

However, such methods generally provide control that lacks quick response and have problems such as increased temperature ripple.

The present invention aims to eliminate the above drawbacks.

[Means for Solving the Problems] The present invention directly detects data related to temporal changes in the state quantity Q (dQ/dt, etc.) by devising a sensor structure.

That is, in the present invention, the state quantity Q(t) of the object at time t, which is placed directly with respect to the object to be detected, is set at the same time t.
a first detection element that converts the state quantity Q of the object to be detected into an electric signal E1(t) at a predetermined time a, a delay element that transmits the state quantity Q of the detected object with a delay of a predetermined time a; and a delay element arranged directly with respect to the delay element; The state quantity Q at the time ta that is transmitted with a delay
(t-a) as the electrical signal E2(t) at time t
a second detection element that converts the output signal E1(t) into a signal E2(t) of the second detection element; The integrated sensor is characterized in that the first detection element, the delay element, and the second detection element are integrally configured.

Each component will be explained below.

The first detection element and the second detection element are elements that convert a state quantity such as temperature or heat of a detection target or gas concentration into an electrical signal. The element may be of a type that directly outputs a voltage signal V or current signal I in response to a change in the state quantity Q, or may be an element that outputs a resistivity ρ (resistance R) in response to a change in the state quantity Q. The change in resistivity ρ is expressed as a voltage signal V
Alternatively, it may be a type of element that detects the current signal I. Note that it is desirable for the first detection element and the second detection element to have the same state quantity-electrical signal (QE) conversion characteristic in terms of sensor accuracy.

The delay element changes the state quantity Q of the object to be detected at a time a
This is an element that delays and transmits the signal to the second detection element.
In other words, due to the presence of the delay element, the second detection element always detects the state at time ta at time t.

When the state quantity Q is the temperature T, it is preferable to use a heat transfer medium such as thin glass, metal, metal compound, or resin as the material of the delay element, and cover the second detection element with the heat transfer medium. Further, when the state quantity is the gas concentration G, a gas permeation resistor such as a glass pipe, a metal orifice, or a resin permeation membrane may be used as the delay element.

The signal processing unit calculates the state quantity Q(t) from the output signals E1(t) and E2(t) of the first detection element and the second detection element.
Compute data regarding temporal changes in . As data regarding the temporal change of the state quantity Q(t),
Not limited to the above dQ/dt, there are various cases such as E1/E2, E1-E2, E1·E2/(E1±E2), (E1-E2)/(E1+E2), etc. As mentioned above, the output signal E2(t) of the second detection element at time t is the state quantity at time t-a as E2(t)=F{Q(t-a)}...(1) Q(t-a)
In particular, the state quantity-electrical signal conversion characteristic (Q
-E conversion characteristics) are equal and there is no attenuation due to the delay element, E2(t)=E1(t-a)...(2) holds true.

The signal processing section can be configured integrally with the sensor using a resistor or the like connected to the first detection element and/or the second detection element, but it may also be configured separately if necessary.

[Effect] State quantities Q such as temperature and gas concentration at time t
(t) is instantaneously detected as an electric signal E1 by the first detection element.
(t).

On the other hand, the state quantity Q(ta) at time ta
is delayed for a time a by a delay element, and then converted into an electrical signal E2(t) by a second detection element at time t.

The signal processing section processes the signals E1(t) and E2(t) to obtain data regarding temporal changes in the state quantity Q(t), and provides the data as control data for the actuating section.

[Examples] The present invention will be described below with reference to specific examples that illustrate the invention.

FIG. 1 is a perspective view schematically showing the configuration of an example sensor, and FIG. 2 is a longitudinal sectional view of the sensor. FIG. 3 is an electrical circuit diagram of the sensor.

In this embodiment, the temperature T is detected as the state quantity Q.

As shown in FIGS. 1 and 2, the sensor of this embodiment includes an outer cylindrical body 5 made of copper having good thermal conductivity, and a structure in which the outer cylindrical body 5 is in contact with the outer cylindrical body 5. a first thermistor 1 which is a housed first detection element;
A second thermistor 2, which is a second detection element, is housed in the outer cylinder 5 apart from the outer cylinder 5; It consists of a delay element 3 made of epoxy resin that delays heat from the outside of the outer cylinder 5 for a predetermined time a before transmitting it to the second thermistor 2.

The temperature-electrical resistance conversion characteristics (TR characteristics) of the first thermistor 1 and the second thermistor 2 are equal;
They are adjusted so that they each exhibit the same resistance value at the same temperature. Therefore, R2(t)=F{T(t-a)}=R1(t-a)...(3) holds true. Here, T is the temperature of the object to be detected, and R1 and R2 are the electrical resistance values of the first thermistor 1 and the second thermistor 2, respectively. That is, the electrical resistance value of the second thermistor 2 at time t is equal to the electrical resistance value of the first thermistor 1 at time ta.

Figure 4 is a graph showing a relatively gradual temperature increase pattern (temperature increase pattern when applying AC30V to an electric heater)
It is a graph which shows the change of the electrical resistance value of the 1st thermistor 1 and the 2nd thermistor 2 of the sensor of a present Example corresponding to the temperature increase pattern of a figure. In addition, Figure 6 shows a relatively rapid temperature rise pattern (for electric heaters).
FIG. 7 is a graph showing the temperature rise pattern when heating is performed by applying AC100V, and FIG.
2 is a graph showing changes in electrical resistance values of thermistor 1 and second thermistor 2. FIG.

In Figure 4, T=kt+To (t≧0) ……(4) holds true. From equation (4), t=(T-To)/k...(5) , and t≧0 T≧To...(6) corresponds to

On the other hand, in Fig. 5, approximately R1 (t) = -Kt + Ro (t≧0) ... (7) and R2 (t) = R1 (t-a) = -K (t-a) + Ro (t ≧a) ...(8) holds true. Note that a≧t≧0 (this means that T≧To
+ak), R2(t) is R2
(t)=Ro...(9).

Substituting (5) into equations (7) and (8) and eliminating t, (7) and
Expressing equation (8) as a function of temperature T, R1 (T) = -K (T - To) / k + Ro = -A (T - To) + Ro (T≧To) ... (10) and R2 ( T)=-K(T-To)/k+Ro+Ka=-A(T-To)+Ro+Ka (T≧To+ak)...(11). Note that A=K/k. Further, FIG. 8 is a graph showing R1 and R2 as a function of temperature T based on FIGS. 4 and 5.

From the above equations (10) and (11), R2(T)-R1(T)=Ka...(12). Here, when evaluating Ka, from equations (7) and (8), K is the rate of change over time in the electrical resistance value R,
That is, it is expressed as K=dR/dt...(13), so the difference Ka between R2(T) and R1(T) is, in other words, , it can be seen that the larger the rate of temperature change of the object to be detected is, the larger it is. In addition, Figure 9 is based on Figures 6 and 7, and R1
and R2 as a function of temperature T.

From the comparison of FIG. 8 and FIG. 9, the above conclusion, that is, with the sensor of this example, the larger the rate of temperature change of the detected object, the larger the difference between R2(T) and R1(T). It is supported.

FIG. 10 is a graph showing a temperature increase pattern when no fire occurs, and FIG. 11 is a graph showing a temperature increase pattern when a fire occurs.

As shown in the figure, the rate of temperature change in the case of fire is large, while the rate of temperature change in the case of non-fire is small.
Therefore, when the sensor of this embodiment is used, the difference between R2(T) and R1(T) becomes large in the case of a fire.

Therefore, by using the sensor of this embodiment, a bridge circuit is constructed as shown in FIG. It is useful to output this to activate the alarm 7, since it is possible to detect the occurrence of a fire from the temperature rise pattern even when the temperature is relatively low. Furthermore, R3 and R4
is a constant resistance, and by selecting the values of R3 and R4, the activation level of the alarm 7 can be set arbitrarily.

In the above description, an example of application to a temperature sensor or a gas sensor has been described, but the invention can also be easily applied to other sensors such as pressure, strain, and optical sensors. In this case, the delay element can be an elastic member such as rubber for pressure and strain, and an opaque member such as frosted glass for light.

[Effects] As described above in detail, the present invention is a sensor that directly detects data regarding changes in state quantities by devising the structure of the sensor.

As described in the embodiment, according to the sensor of the present invention, the state quantity Q is
When data regarding the rate of change over time is required, an abnormality such as a fire can be detected at an early stage without using a hard circuit such as a differential circuit or a microcomputer.
Further, temperature control can be performed without problems such as temperature ripple.

Furthermore, it is not only inexpensive because it does not require a microcomputer, but also solves problems such as reduced reliability due to circuit complexity, environmental resistance of circuit components, and poor installation ease due to larger equipment. be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the configuration of an example sensor, and FIG. 2 is a longitudinal sectional view of the sensor. FIG. 3 is an electrical circuit diagram of the sensor. Figure 4 is a graph showing a relatively gradual temperature increase pattern (temperature increase pattern when heating by applying AC30V to an electric heater), and Figure 5 corresponds to the temperature increase pattern in Figure 4. It is a graph showing changes in the electrical resistance values of the first thermistor 1 and the second thermistor 2 of the sensor of the present example. In addition, Figure 6 shows a relatively rapid temperature rise pattern (for electric heaters).
FIG. 7 is a graph showing the temperature rise pattern when heating is performed by applying AC100V, and FIG.
2 is a graph showing changes in electrical resistance values of thermistor 1 and second thermistor 2. FIG. FIG. 8 is a graph showing R1 and R2 as a function of temperature T based on FIGS. 4 and 5. FIG. 9 is a graph showing R1 and R2 as a function of temperature T based on FIGS. 6 and 7. FIG. 10 is a graph showing a temperature increase pattern when no fire occurs, and FIG. 11 is a graph showing a temperature increase pattern when a fire occurs. 1...First detection element, 2...Second detection element, 3
... Delay element, 4... Heat insulation member.

Claims (1)

[Scope of Claims] 1. A first detection element that is arranged directly with respect to an object to be detected and converts the state quantity of the object into an electrical signal; a second detection element that is arranged directly with respect to the delay element and converts the delayed and transmitted state quantity into an electrical signal; a signal processing unit that processes according to the output signal of the second detection element, and at least the first detection element, the delay element, and the second delay element are integrally configured. Body shape sensor. 2. The integrated sensor according to claim 1, wherein the state quantity of the object to be detected is temperature, and a heat transfer medium is used as the delay element. 3. The integrated sensor according to claim 1, wherein the state quantity of the object to be detected is a gas concentration, and a gas permeation resistor is used as the delay element. 4. In claim 1, the signal processing section is an integrated type that outputs a drive signal according to a difference between an output signal level of the first detection element and an output signal level of the second detection element. sensor. 5. The integrated sensor according to claim 1, wherein the first detection element and the second detection element have the same conversion characteristics.