JP2008256513A - Measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of simplification, cost reduction, and quick and accurate detection of the state of a measuring object, concerning a measuring device constituted so that the state of the measuring object such as flow velocity or a concentration is detected based on an output signal from a sensor element by installing the sensor element for outputting the output signal corresponding to the state of the measuring object. <P>SOLUTION: This device is equipped with an accumulated using time deriving means 29 for deriving an accumulated using time by accumulating using time of the sensor element 6, and a sensitivity correction means 25 for correcting sensitivity of the sensor element based on the accumulated using time of the sensor element 6, and is also equipped with a temperature deriving means 27 for deriving the temperature of the sensor element 6. The accumulated using time deriving means 29 derives the accumulated using time by accumulating a temperature-corrected using time acquired by correcting the using time of the sensor element 6 corresponding to the temperature of the sensor element 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a measurement apparatus configured to install a sensor element that outputs an output signal corresponding to a state of a measurement target and detect the state of the measurement target based on the output signal of the sensor element.

  As this type of measuring apparatus, a pair of ultrasonic transmitters / receivers capable of transmitting / receiving ultrasonic waves to / from each other are installed as the sensor elements on the upstream side and the downstream side of the measurement flow path through which the fluid flows. Propagation time measuring means for receiving the ultrasonic wave transmitted from one side of the transceiver on the other side and measuring the propagation time of the ultrasonic wave between the pair of ultrasonic transceivers, and the measurement result of the propagation time measuring means 2. Description of the Related Art An ultrasonic meter device having a flow velocity value calculation means for deriving the flow velocity value based on the above is known. (For example, see Patent Document 1).

  Specifically, the ultrasonic meter device includes a forward propagation time t1 in which ultrasonic waves propagate in the forward direction along the fluid flow direction between the pair of ultrasonic transceivers by the propagation time measuring unit, The backward propagation time t2 in which the ultrasonic wave propagates in the opposite direction to the forward direction is measured. Then, when the instantaneous flow velocity of the fluid is v ′, the sound velocity is C, and the distance between the pair of ultrasonic transmitters / receivers is L in the facing direction between the pair of ultrasonic transmitters / receivers, the above measured forward propagation time t1. And the reverse propagation time t2 can be expressed as shown in the following formulas (1) and (2). Therefore, the flow velocity v ′ is obtained by the following formula (3) regardless of the sound speed C. be able to.

t1 = L / (C + v ′)
t2 = L / (Cv ′)
v ′ = L · (1 / t1-1 / t2) / 2

  By utilizing this, the flow velocity value calculation means uses the flow velocity v ′ obtained by the above equation (3), and the flow velocity of the fluid in the measurement channel, or the flow rate break of the measurement channel in the flow velocity. A flow rate obtained by multiplying the area can be derived as a flow velocity value.

Further, in the conventional ultrasonic meter device, the received signal of the ultrasonic transmitter / receiver that has received the ultrasonic wave has a waveform that attenuates after the amplitude gradually increases, even if it is amplified to the maximum set voltage. Therefore, the time immediately after the reception signal is received has a very small amplitude, and it is difficult to accurately recognize the reception time. In the present application, the waveform of the received signal indicates the ratio of the maximum voltage of each wave to the maximum voltage of the entire received signal.
Therefore, the propagation time measuring means determines the ultrasonic wave reception time of the ultrasonic wave transmitter / receiver with reference to the time point when the amplitude of the received signal becomes large enough to be accurately recognized. The received signal and the reference voltage are compared for determination.
For example, the propagation time measuring means obtains a time point (hereinafter referred to as “zero cross point”) when the received signal becomes zero level immediately after the received signal reaches the reference voltage. Assuming that the waveform of the received signal is constant, the zero cross point obtained in this way coincides with the zero cross point of the specific wave from the reception time point (hereinafter referred to as “target wave”). The delay time from to the zero cross point can be recognized in advance as a value that is a fixed multiple of the period of the received signal.
Therefore, the propagation time measuring means can accurately determine the time point before the delay time from the zero cross point obtained as described above as the reception time point.

However, when the waveform of the received signal changes, for example, the wave of the received signal that exceeds the reference voltage is not the target wave but the waves before and after the target wave, and the reception time may not be accurately determined.
Therefore, in the conventional ultrasonic meter device, while changing the reference voltage, the propagation time of the ultrasonic wave between the pair of ultrasonic transmitters / receivers and the time difference from the time when the received signal reaches the reference voltage to the zero cross point are sequentially changed. Thus, the optimum reference voltage detection process for detecting the optimum reference voltage for detecting the zero-cross point of the target wave is executed from the propagation time and the change state of the time difference.
The flow velocity value is derived from the propagation time of the ultrasonic wave measured by setting the reference voltage to the optimum one detected by the optimum reference voltage detection process.
In this type of ultrasonic meter device, even when the received signal changes, the optimum reference voltage for detecting the zero-cross point of the target wave is detected by executing the optimum reference voltage detection process. Thus, an accurate flow velocity value can be derived.

  As another measuring device, a gas detection element whose electric resistance changes in response to a specific component is arranged as the sensor element in the measurement channel, a heater for heating the gas detection element, and the gas detection element There has been known a gas detection device including a gas detection means for determining the presence or concentration of a specific component based on an output voltage that changes in accordance with a change in electrical resistance. Further, such a gas detection device is employed in a gas alarm device configured to perform an alarm operation when the concentration of methane or carbon monoxide as the specific component reaches a dangerous level (for example, patent document) 2).

JP 2003-106882 A Japanese Patent Laid-Open No. 11-283147

In the measurement apparatus such as the ultrasonic meter apparatus and the gas detection apparatus as described above, a sensor element that outputs an output signal corresponding to a state of a measurement target such as a fluid flowing in the measurement flow path or a specific component existing in the measurement flow path. The sensitivity gradually decreases as the accumulated use time becomes longer and the deterioration progresses.
In addition, even when the sensitivity of the sensor element is corrected based on the accumulated usage time, the sensitivity of the sensor element cannot be corrected to a normal state due to a difference in the installation environment. It has been difficult to accurately detect the state of a measurement object such as concentration.

  Further, in the ultrasonic meter device described in Patent Document 1, the optimum reference voltage detection process is executed as described above to accurately derive the flow velocity value. There is a problem that the cost is increased and the time until the flow velocity value is derived becomes longer. In addition, if the time until the flow velocity value is derived becomes longer, the flow velocity of the fluid may change significantly while the time elapses, and the reference voltage detected in the optimum reference voltage detection process is the next flow velocity value. There is a problem that it is no longer optimal for deriving the value, and an accurate flow velocity value cannot be derived.

  The present invention has been made in view of the above problems, and its purpose is to install a sensor element that outputs an output signal corresponding to the state of the measurement target, and to measure the measurement target based on the output signal of the sensor element. In a measuring apparatus configured to detect a state such as a flow rate and a concentration, it is possible to simplify and reduce the cost, and to provide a technique capable of detecting a state of a measurement target quickly and accurately.

In order to achieve the above object, a measuring apparatus according to the present invention is provided with a sensor element that outputs an output signal corresponding to a state of a measurement target, and detects the state of the measurement target based on the output signal of the sensor element. The first characteristic configuration is a cumulative usage time deriving unit that accumulates the usage time of the sensor element to derive the cumulative usage time,
Sensitivity correction means for correcting the sensitivity of the sensor element based on the cumulative use time of the sensor element derived by the cumulative use time deriving means;
Temperature deriving means for deriving the temperature of the sensor element;
The cumulative usage time deriving unit is configured to derive the cumulative usage time by accumulating a temperature corrected usage time obtained by correcting the usage time of the sensor element according to the temperature of the sensor element derived by the temperature deriving unit. It is in the point.

  As a result of earnest research, the inventors of the present application have found that the sensor element has a flow rate, a flow rate, a concentration, and the like based on the output signal of the sensor element installed in the measurement flow path where the measurement object exists. It has been found that in addition to the increase in the cumulative usage time, the temperature history of the sensor element so far is the main factor that decreases the sensitivity of the sensor element. Then, if the accumulated usage time of the sensor element is derived in consideration of the temperature history of this sensor, a correlation between the increase in the accumulated usage time and the decrease in the sensitivity of the sensor element is obtained in advance by experiments, etc. It has been found that if the sensor sensitivity is corrected by the accumulated use time considering the temperature history using the correlation, the state of the measurement object can be accurately detected, and the present invention has been completed.

  That is, according to the first feature configuration, in deriving the accumulated use time, the accumulated time taking into account the temperature history by accumulating the temperature correction use time sequentially corrected by the temperature of the sensor element by the accumulated time deriving means. The sensitivity of the sensor element can be corrected by the sensitivity correction means using the temperature accumulated use in consideration of the temperature history, and as a result, the output signal of the sensor element that has been sequentially corrected for sensitivity can be quickly and The state of the measurement object can be detected accurately.

  In the second characteristic configuration of the measuring apparatus according to the present invention, in addition to the first characteristic configuration, the cumulative use time deriving means is calculated by the Arrhenius rule or the 10 ° C. double rule using the temperature of the sensor element. The temperature correction coefficient is integrated with the usage time of the sensor element to obtain the temperature correction usage time.

  According to the second characteristic configuration, the temperature influence coefficient calculated by the Arrhenius law or the 10 ° C. double law known as the law for predicting the lifetime due to the temperature stress of the semiconductor or the like is calculated using the temperature of the sensor element. It is possible to obtain the temperature correction usage time by calculating and integrating the temperature influence coefficient with the usage time of the sensor element. Then, the sensitivity of the sensor element is corrected based on the accumulated use time obtained by accumulating the temperature correction use time obtained by using the Arrhenius law or the 10 ° C. double rule in this way, thereby detecting the state of the measurement object more accurately. can do.

The third characteristic configuration of the measuring device according to the present invention is, in addition to any of the first to second characteristic configurations described above, a fluid flowing in a measurement channel as the measurement target,
On the upstream side and the downstream side of the measurement channel, a pair of ultrasonic transmitters / receivers capable of transmitting / receiving ultrasonic waves to each other are installed as the sensor elements,
The ultrasonic wave transmitted from one side of the pair of ultrasonic transceivers is received on the other side, and the reception time of the ultrasonic wave of the ultrasonic transceiver is determined by the received signal and the reference voltage of the ultrasonic transceiver. Propagation time measuring means for determining by comparison and measuring the propagation time of ultrasonic waves between the pair of ultrasonic transceivers;
The ultrasonic meter device includes a flow velocity value calculating unit that derives a flow velocity value related to the flow velocity of the fluid flowing through the measurement flow path based on the measurement result of the propagation time measuring unit.

According to the third characteristic configuration described above, the measurement apparatus according to the present invention described so far has a pair of ultrasonic transmitters / receivers arranged as sensor elements in the measurement flow path, and the output signals of the pair of ultrasonic transmitters / receivers are used. Thus, it can be configured as an ultrasonic meter device for deriving a flow velocity value relating to a flow velocity such as a fluid flow velocity or a flow rate as the state of the measurement target.
That is, the sensitivity correction means corrects the output signal of the ultrasonic transmitter / receiver and the reference voltage to be compared with the output signal based on the accumulated usage time considering the temperature history of the ultrasonic transmitter / receiver. By accurately and quickly correcting the sensitivity of the transmitter / receiver, the propagation time measurement means compares the output signal of the ultrasonic transmitter / receiver with the reference voltage to accurately determine the reception time point and measures the correct propagation time. can do.
Therefore, it is possible to realize an ultrasonic meter device that derives a flow velocity value relating to the flow velocity of the fluid flowing through the measurement channel with high accuracy.

In addition to any of the first to second characteristic configurations described above, the fourth characteristic configuration of the measuring device according to the present invention is a specific component present in the measurement flow path as a measurement target,
In the measurement channel, a gas detection element whose electrical resistance changes in response to the specific component is disposed as the sensor element,
A heater for heating the gas detection element;
The gas detection device includes gas detection means for determining the presence or concentration of the specific component based on an output voltage that changes in accordance with a change in electrical resistance of the gas detection element.

According to the fourth characteristic configuration, the measurement apparatus according to the present invention described so far has the gas detection element disposed in the measurement flow path as a sensor element, and the state of the measurement target is measured using the output voltage of the gas detection element. As a gas detection device for determining the presence or concentration of a specific component in the measurement channel.
That is, the output of the gas detection element is output by the gas detection means by correcting the output voltage of the gas detection element accurately and quickly by the accumulated use time in consideration of the temperature history of the gas detection element. Based on the voltage, the presence or concentration of the specific component can be determined with high accuracy.

[Ultrasonic meter device]
An ultrasonic meter device as an embodiment of a measuring device according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a flow velocity relating to the flow velocity such as a flow velocity and a flow velocity of a gas g (an example of a measurement target) flowing through the measurement channel 2 by the ultrasonic meter device (hereinafter, abbreviated as “meter device”) of the present embodiment. FIG. 2 is a side sectional view of the meter device in a state in which values are being derived, FIG. 2 is a diagram illustrating a state of a reception signal of the ultrasonic transceiver 6, and FIG. 3 is a cumulative diagram of the ultrasonic transceiver 6. It is a graph which shows the relationship of the setting reference voltage with respect to use time, and FIG. 4 is a sectional side view of the meter apparatus of another embodiment.

First, the basic configuration of the meter device will be described.
As shown in FIG. 1, the meter device is arranged at both ends of the measurement channel 2 in a direction that obliquely crosses between the upstream side and the downstream side, and transmits and receives ultrasonic waves along the transverse direction. Measurement is performed by a pair of possible ultrasonic transmitters / receivers (hereinafter abbreviated as “transmitter / receiver”) 6 (an example of a sensor element) and the propagation state of ultrasonic waves in the measurement channel 2 measured by the pair of transmitter / receivers 6. A control device 50 configured to derive the flow velocity value of the gas g flowing through the flow path 2 as the state of the gas g is provided.

  The transmitter / receiver 6a installed on the upstream side of the measurement channel 2 and the transmitter / receiver 6b installed on the downstream side of the measurement channel 2 are installed facing each other at a position separated by a distance L. The facing direction of the transmitter / receiver 6 and the flow direction of the gas g flowing through the measurement flow path 2 (the direction along the central axis of the measurement flow path 2) form an angle θ.

  In addition, when a drive pulse that is an electrical signal is input from the control device 50 side, the transmitter / receiver 6 transmits an ultrasonic wave toward the other transmitter / receiver 6 side, while transmitting from the other transmitter / receiver 6 side. When the received ultrasonic wave is received, a reception signal which is an electric signal is output to the control device 50 side.

  The control device 50 is configured by a microcomputer including a storage medium including a memory, a CPU, an input / output unit, and the like, and the computer executes a predetermined program, thereby causing a propagation time measuring unit 10 and a flow velocity value calculation described later. It functions as various means such as means 20, reference voltage setting means 25, temperature deriving means 27, accumulated usage time deriving means 29, and the like. Hereinafter, a detailed configuration of each unit will be described.

  The propagation time measuring means 10 in which the control device 50 functions includes a switching unit 11 that switches between a transmission state of a driving pulse and a reception state of a reception signal for each of the pair of transceivers 6, and ultrasonic waves to the transceiver 6 through the switching unit 11. A driving unit 12 for outputting a driving pulse for generating a signal, an amplifying unit 13 for amplifying a received signal of the transceiver 6 inputted through the switching unit 11, and a reference voltage to be described later for the received signal amplified by the amplifying unit 13. The reception time determination unit 14 that determines the reception time of the ultrasonic waves of the transmitter / receiver 6 as compared with the time measurement that is measured as the propagation time of the ultrasonic waves between the pair of transmitters / receivers 6 based on the determination result of the reception time determination unit 14 Part 15.

  The switching unit 11 transmits the drive pulse input from the drive unit 12 to the upstream side transmitter / receiver 6 a of the pair of transmitters / receivers 6, and receives the reception signal received from the downstream side transmitter / receiver 6 b to the amplification unit 13. In contrast to the forward propagation state to be output, conversely, the drive pulse input from the drive unit 12 is transmitted to the downstream transmitter / receiver 6b of the pair of transmitters / receivers 6, and the received signal received from the upstream transmitter / receiver 6a is transmitted. It is configured to switch the reverse propagation state output to the amplifying unit 13.

  As shown in FIG. 1, the reception time point determination unit 14 obtains a zero cross point at which the reception signal amplified by the amplification unit 13 becomes zero level immediately after reaching a predetermined reference voltage, and the zero cross point is obtained. The time point before a predetermined delay time set in advance is determined as the reception time point.

  Then, the time measuring unit 15 refers to the time from the transmission time when the driving pulse is output by the driving unit 12 to the reception time determined by the reception time determining unit 14 while referring to the time measured by the timer 28. It is configured to measure the propagation time of ultrasonic waves between the six.

  Then, the control device 50 switches the switching unit 11 between the forward propagation state and the backward propagation state, so that the timer unit 15 in the forward direction along the flow direction of the gas g flowing through the measurement flow channel 2. The ultrasonic wave is transmitted in a direction opposite to the forward direction along the flow direction of the gas g flowing through the measurement flow path 2 and the forward propagation time t1 in which the ultrasonic wave propagates between the pair of transceivers 6 in the direction. It is configured to measure the backward propagation time t2 that propagates between the transceivers 6.

  The flow velocity value calculation means 20 in which the control device 50 functions is configured to derive a flow velocity value related to the flow velocity of the gas g flowing through the measurement flow path 2 based on the measurement result of the propagation time measurement means 10. The method for deriving the flow velocity value will be described below.

The instantaneous flow velocity of the gas g along the facing direction between the pair of transceivers 6 is denoted by v ′, the instantaneous flow velocity along the flow direction of the measurement flow path 2 is denoted by v, and the angle between the facing direction and the flow direction is θ. Assuming that the distance between the pair of transceivers 6 is L and the sound velocity in the gas g is C, the forward propagation time t1 and the backward propagation time t2 measured by the propagation time measuring means 10 are as follows: As shown in FIG.
t1 = L / (C + v ′) = L / (C + v · cos θ)
t2 = L / (Cv ′) = L / (Cv · cos θ)

From these equations, the instantaneous flow velocity v is a function obtained only from the forward propagation time t1, the backward propagation time t2, and the distance L as shown in the following equation.
v = L · (1 / t1-1 / t2) / (2 · cos θ)

Therefore, the flow velocity value calculating means 20 uses the above function to calculate the instantaneous flow velocity of the gas g flowing through the measurement flow path 2 from the forward propagation time t1 and the backward propagation time t2 measured by the propagation time measuring means 10. per unit time obtained by deriving v and calculating the instantaneous flow rate v itself, or the instantaneous flow rate v obtained by multiplying the instantaneous flow rate v by the cross-sectional area of the measurement flow path 2 or the instantaneous flow rate per unit time. Is derived as the flow velocity value.
Further, the control device 50 can display or store the flow velocity value derived in this way or output it to the outside.

Next, the characteristic configuration of the meter device will be described.
In order to stabilize the strength of the received signal after amplification of the transceiver, the amplifying unit 13 maximizes the preset set voltage for the received signal of the transceiver 6 input through the switching unit 11. It is comprised as an amplification means to amplify.
Then, the received signal of the transmitter / receiver 6 that has received the ultrasonic wave (output of the amplifying unit 13) has a waveform that attenuates after the amplitude gradually increases, as shown in FIG. Since the waveform of the received signal changes due to the change in the accumulated usage time, the reception time determination unit 14 determines the ultrasonic reception time of the transmitter / receiver 6 by comparing the received signal of the transmitter / receiver 6 with a reference voltage. In this case, if the reference voltage is constant, the waveform of the received signal changes due to changes in the temperature and the accumulated usage time, and the wave of the received signal exceeding the predetermined reference voltage is not a predetermined target wave. As a result, the reception time may not be accurately determined.

Therefore, the meter device can be simplified and reduced in cost, and in order to quickly and accurately derive the flow velocity value, as shown in FIG. 1, the usage time of the transceiver 6 is accumulated to derive the accumulated usage time. The accumulated usage time deriving means 29 and the sensitivity correction means for correcting the sensitivity of the transceiver 6 based on the accumulated usage time of the transceiver 6 derived by the accumulated usage time deriving means 29 are used as the accumulated usage time of the transceiver 6. A reference voltage setting means 25 for setting a reference voltage based on the above and a temperature deriving means 27 for deriving the temperature of the transceiver 6 are provided in a form in which the control device 50 functions. 29 is configured to derive the accumulated usage time by accumulating the temperature-corrected usage time obtained by correcting the usage time of the transceiver 6 according to the temperature of the transceiver 6 derived by the temperature deriving means 27.
Hereinafter, these detailed configurations will be described.

  A peak voltage measuring unit 26 that measures a peak voltage of a reception signal before amplification in the transceiver 6 input to the amplifying unit 13 as an amplifying unit is provided. The temperature deriving unit 27 performs transmission / reception based on the peak voltage. The temperature of the vessel 6 is derived.

That is, using the fact that the peak voltage decreases as the temperature of the transmitter / receiver 6 decreases, the correlation between the temperature of the transmitter / receiver 6 and the peak voltage of the received signal of the transmitter / receiver 6 is obtained in advance by experiments or the like. be able to.
Prior to the measurement of the propagation time by the propagation time measurement means 10, the peak voltage measurement means 26 transmits the drive pulse input from the drive unit 12 to the transceiver 6 on one side and transmits the transmitter / receiver on the other side. The maximum voltage of the received signal received from 6 before amplification is measured as the peak voltage.

  Then, the temperature deriving unit 27 refers to the correlation between the temperature of the transmitter / receiver 6 and the peak voltage obtained in advance, and uses the peak voltage of the received signal derived by the peak voltage measuring unit 26 to calculate the temperature. The temperature of the transceiver 6 can be derived.

  On the other hand, the accumulated usage time deriving means 29 refers to the time measured by the timer 28 and starts using the meter device or replaces the transmitter / receiver 6 with a new one and uses it up to the present time. The accumulated value of time is derived as the accumulated usage time of the transceiver 6.

  Further, the accumulated usage time deriving means 29 corrects the usage time longer as the temperature rises, for example, so that the accumulated usage time more accurately indicates the aging deterioration state of the transmitter / receiver 6. In such a form that the use time is corrected to be shorter as the value becomes lower, the use time of the transmitter / receiver 6 is corrected by the temperature of the transmitter / receiver 6 derived by the temperature deriving means 27, and the corrected temperature correction use time is accumulated, The cumulative usage time is derived.

As a method for deriving the temperature correction use time, the temperature influence coefficient K (T) calculated by the Arrhenius law or the 10 ° C. double law known as a law for predicting the lifetime due to temperature stress of a semiconductor or the like is used. The temperature K of the transmitter / receiver 6 is used for calculation, and the temperature influence coefficient K (T) is integrated with the usage time t of the transmitter / receiver 6 to obtain [K (T) × t] as the temperature-corrected usage time. it can.
That is, the temperature influence coefficient Ka (T) obtained by the Arrhenius rule and the temperature influence coefficient K ₁₀ (T) obtained by the 10 ° C. double rule can be obtained by the following equations.
Ka (T) = AeΔ ^{E / kT}
K ₁₀ (T) = B × 2ΔT ^{/ 10}
A, B: constant k: Botman constant (8.6159 × 10 ⁻⁵ [eV / K])
ΔE: activation energy [eV]
T: Temperature of the transceiver 6 [K]
t: Usage time of transmitter / receiver 6 [h]

Further, as the temperature influence coefficient K (T), a temperature influence correction coefficient K ′ (T) obtained by the following formula is used instead of the above temperature influence coefficients Ka (T) and K ₁₀ (T). It doesn't matter.

K ′ (T) = CT ^m eΔE ^{′ / kT}
ΔE ′ = ΔE−mkT
C, m: constant

  Then, the reference voltage setting means 25 is based on the derivation result of the accumulated use time deriving means 29, that is, the accumulated use time of the transceiver 6 obtained by time integration of the temperature correction use time [K (T) × t]. Thus, the reference voltage used for determining the reception time point in the reception signal by the reception time point determination unit 14 of the propagation time measuring means 10 is quickly set to the optimum set reference voltage that matches the waveform of the reception signal.

  Specifically, as shown in FIG. 3, for example, the reference voltage setting unit 25 increases the target wave in the amplified received signal as the cumulative usage time Ti of the transceiver 6 derived by the cumulative usage time deriving unit 29 is longer. Since the maximum voltage of the previous wave increases, the set reference voltage is shifted to a higher side in accordance with the increase.

  Therefore, the reference voltage used for determining the reception time point in the reception signal by the reception time point determination unit 14 of the propagation time measuring means 10 is set by the reference voltage setting means 25 to the optimum set reference voltage. The first wave in the received signal that exceeds the set reference voltage is almost certainly the specific target wave from the reception time, and the zero cross point and the reception time are determined based on the time when the received signal in the target wave reaches the reference voltage. It is determined accurately and the accurate propagation time is measured.

Further, the accumulated use time derived by the accumulated use time deriving means 29 takes into account the temperature history of the transmitter / receiver 6 so that the deterioration state of the transmitter / receiver 6 can be accurately determined.
Therefore, when the accumulated use time derived by the accumulated use time deriving means 29 exceeds a preset allowable value, the LED is turned on to prompt the user to replace or maintain the transceiver 6. Or a notification process such as outputting an alarm can be performed.

  In the above embodiment, the temperature deriving means 27 is configured to derive the temperature of the transceiver 6 based on the peak voltage of the reception signal of the transceiver 6, but separately configured as follows. You can also.

That is, the meter device shown in FIG. 4 includes a sound speed calculation means 30 for deriving the sound speed in the measurement flow path 2 based on the measurement result of the propagation time measurement means 10, and the temperature deriving means 31 that the control device 51 functions is The temperature of the transmitter / receiver 6 is derived based on the speed of sound. Since the transmitter / receiver 6 is installed in the measurement channel 2, the temperature of the transmitter / receiver 6 is assumed to be the temperature in the measurement channel 2.
In the description of the meter device shown in FIG. 4, the same components as those of the meter device shown in FIG.

Since the sound velocity C in the measurement channel is a function of the temperature Th of the transmitter / receiver 6 as shown in the following equation, if the sound velocity C is obtained, the temperature Th of the transmitter / receiver 6 can be obtained.
C = C1 + C2 · Th
C1, C2: Constant

The sound speed calculation means 30 can derive the sound speed C from, for example, the forward propagation time t1 and the reverse propagation time t2 measured immediately before by the propagation time measurement means 10 as shown in the following equation.
t1 = L / (C + v ′) = L / (C + v · cos θ)
t2 = L / (Cv ′) = L / (Cv · cos θ)
C = L · (1 / t1 + 1 / t2) / (2 · cos θ)

  The temperature deriving means 31 substitutes the sound speed C derived by the sound speed calculating means 30 into a function of the sound speed C and the temperature Th of the transmitter / receiver 6 to obtain the temperature Th of the transmitter / receiver 6. it can.

  Of course, the temperature deriving means 31 may be configured to directly derive the temperature of the transmitter / receiver 6 based on the output of a temperature sensor installed in the vicinity of the transmitter / receiver 6.

  Moreover, in the said embodiment, the reception time determination part 14 is a delay time before the zero crossing point which became a zero level immediately after the time when the reception signal amplified by the amplification part 13 reached the reference voltage. Although it is configured to determine the time as the reception time, the reception is performed in another form, for example, when the reception signal reaches the reference voltage or the zero cross point itself is determined as the reception time. The signal may be compared with a reference voltage to determine the time of reception of the ultrasonic wave of the transceiver 6.

In the above embodiment, the amplifying unit 13 that amplifies the received signal of the transmitter / receiver 6 so as to maximize the set voltage is provided. If there is no problem, the amplifying unit is used to amplify the received signal to a predetermined level. It may be modified to amplify at a rate, or the amplifying unit may be omitted.
When the amplification unit is modified or omitted in this way, the reference voltage can be set and adjusted based on the ratio of the received signal to the peak voltage.

  When the amplification unit is configured to amplify the received signal at a predetermined amplification factor, the reference voltage set by the reference voltage setting unit 25 is set to a fixed value and the sensitivity for correcting the sensitivity of the transmitter / receiver 6 is set. As a correction means, for example, the amplification factor of the amplification section is corrected in such a manner that the amplification factor is shifted to the increasing side as the cumulative usage time Ti of the transmitter / receiver 6 derived by the cumulative usage time deriving unit 29 is longer. It doesn't matter.

[Gas detector]
Next, a gas detection apparatus as an embodiment of a measurement apparatus according to the present invention will be described based on the drawings.
FIG. 5 shows a gas in a state where the presence or concentration of methane or carbon monoxide (an example of a specific component as a measurement target) is determined in the air a flowing through the measurement channel 52 by the gas detection device of the present embodiment. It is a sectional side view of a detection.

The gas detection device is configured as a gas alarm device configured to determine the presence or concentration of methane or carbon monoxide in the air a and perform an alarm operation when the concentration of methane or carbon monoxide reaches a dangerous level. ing.
That is, as shown in FIG. 5, a gas detection element 56 whose electric resistance changes in response to methane or carbon monoxide is arranged as a sensor element in a measurement flow path 52 through which air a flows, and further, the gas detection element 56 And a control functioning as a gas detection means 63 for determining the presence or concentration of methane or carbon monoxide in the air a based on an output voltage that changes in accordance with a change in electrical resistance of the gas detection element 56. Device 60.

The gas detection element 56 is an output detection function in which the control device 60 functions as a voltage value obtained by converting a change in electric resistance of the gas detection element 56 (hereinafter, simply referred to as “output voltage”). The gas detection element output circuit 57 for outputting to the means 61 side is connected.
On the other hand, the heater 58 is connected to a heater drive circuit 59 that drives the heater 58. The heater drive circuit 59 is connected to the heater 58 in response to a control command from the heating control means 68 that functions by the control device 60. Control the output.

  The control device 60 is configured by a microcomputer having a storage medium including a memory, a CPU, an input / output unit, and the like, and when the computer executes a predetermined program, an output detection unit 61 and an output correction unit which will be described later 62, functions as various means such as a gas detection means 63, a notification means 64, a temperature deriving means 65, a cumulative use time deriving means 66, a heating control means 68, and the like. Hereinafter, a detailed configuration of various means will be described.

The output detection means 61 samples the output voltage of the gas detection element 56 at a predetermined period, and sends it to the gas detection means 63 via an output correction means 62 described later.
On the other hand, the heating control means 68 heats the heater drive circuit 59 in such a manner that the operating temperature of the gas detection element 56 is alternately switched between a high temperature range and a low temperature range at a sampling period of the output voltage by the output detection means 61. Take control. The high temperature region is set to a temperature (eg, 420 ° C.) at which the gas detection element 56 is sensitive to methane, and the low temperature region is sensitive to the carbon monoxide. It is set as a temperature to exert (for example, 80 ° C.).

Then, the gas detection means 63 determines the presence or concentration of methane in the air a based on the methane sensitivity of the gas detection element 56 from the output voltage in the high temperature range, while the output in the low temperature range. From the voltage, the presence or concentration of carbon monoxide in the air a is determined based on the carbon monoxide sensitivity of the gas detection element 56.
Further, when the gas detection means 63 detects methane or carbon monoxide, the notification means 64 notifies the outside by turning on an LED or outputting an alarm.

Next, the characteristic configuration of the gas detection device will be described.
Since the magnitude of the output voltage of the gas detection element 56 changes depending on the temperature of the gas detection element 56 and the change in the cumulative usage time, the presence or concentration of methane or carbon monoxide is determined by the gas detection means 63. In some cases, accurate determination may not be possible based on the magnitude of the output voltage.

Therefore, the gas detection device can be simplified and reduced in cost, and in order to quickly and accurately determine the presence or concentration of methane or carbon monoxide, as shown in FIG. As a cumulative use time deriving unit 66 for deriving the cumulative use time, and a sensitivity correction unit for correcting the sensitivity of the gas detection element 56 based on the cumulative use time of the gas detection element 56 derived by the cumulative use time deriving unit 66. The control device 60 includes an output correction means 62 that corrects the output voltage based on the accumulated usage time of the gas detection element 56 and a temperature derivation means 65 that derives the temperature of the gas detection element 56 in a form in which the control device 60 functions. Further, the accumulated use time deriving means 66 corrects the use time of the gas detection element 56 in accordance with the temperature of the gas detection element 56 derived by the temperature deriving means 65. By accumulating between it is configured to derive the cumulative usage time.
Hereinafter, these detailed configurations will be described.

  The temperature of the gas detection element 56 is derived from an output signal of a temperature sensor (not shown) provided in the temperature deriving means 65 and the measurement flow path 52. The temperature deriving means 27 may be configured to derive the temperature of the gas detection element 56 from the heating control signal of the heating control means 68.

  On the other hand, the cumulative use time deriving means 66 refers to the time measured by the timer 28 and starts using the gas detection device or replaces the gas detection element 56 with a new one until the present time. The cumulative value of the usage time is derived as the cumulative usage time of the gas detection element 56.

  Further, the accumulated use time deriving means 66 corrects the use time longer as the temperature increases, for example, so that the accumulated use time more accurately indicates the aging deterioration state of the gas detection element 56, and conversely. In such a form that the use time is corrected to be shorter as the temperature is lower, the use time of the gas detection element 56 is corrected by the temperature of the gas detection element 56 derived by the temperature deriving means 65, and the corrected temperature correction use time is accumulated. Thus, the accumulated usage time is derived.

  In addition, as a method for deriving the temperature correction use time, as in the embodiment of the ultrasonic meter device described above, the temperature influence calculated by the Arrhenius rule or the 10 ° C. double rule is used as the temperature of the gas detection element 56. And the temperature influence coefficient integrated with the usage time of the gas detection element 56 is obtained as the temperature correction usage time.

  Then, the output correction means 62 is based on the derivation result of the cumulative use time deriving means 66, that is, the cumulative use time of the gas detection element 56 obtained by integrating the temperature correction use time. Correct the output voltage.

Specifically, the output correction means 62 increases the output voltage as the cumulative use time increases because the output voltage decreases due to deterioration of the gas detection element 56 as the cumulative use time of the gas detection element 56 increases. To correct.
Therefore, since an output voltage in which fluctuations due to the accumulated use time are suppressed is sent to the gas detection means 63, the presence or concentration or the concentration of methane or carbon monoxide is accurately determined from the output voltage. It will be.

Further, the accumulated use time derived by the accumulated use time deriving means 66 takes into account the temperature history of the gas detection element 56, and can accurately determine the deterioration state of the gas detection element 56.
Therefore, when the accumulated use time derived by the accumulated use time deriving means 66 exceeds a preset allowable value, the LED is turned on to prompt the user to replace or maintain the transceiver 6. Or a notification process such as outputting an alarm can be performed.

  In each of the above-described embodiments, the measurement target is methane or carbon monoxide in the gas g and the air a existing in the measurement flow paths 2 and 52. The present invention can be applied.

  The measurement device according to the present invention is provided with a sensor element that outputs an output signal corresponding to the state of the measurement target, such as an ultrasonic meter device or a gas detection device, and the measurement target based on the output signal of the sensor element. In a measuring apparatus configured to detect the flow rate, concentration, and other conditions of the apparatus, it can be simplified and inexpensive, and can be effectively used as a device capable of detecting the state of the measurement object quickly and accurately. .

Schematic configuration diagram of ultrasonic meter device The figure which shows the state of the received signal of the ultrasonic transmitter / receiver 6 The graph which shows the relationship of the setting reference voltage with respect to the accumulation usage time of the ultrasonic transceiver Schematic configuration diagram of gas detector Schematic configuration diagram of gas detector

Explanation of symbols

2, 52: Measurement channel 6: Ultrasonic transceiver (sensor element)
25: Reference voltage setting means (sensitivity correction means)
27, 31, 65: Temperature deriving means 29, 66: Cumulative usage time deriving means 50, 51, 60: Control device 56: Gas detection element (sensor element)
62: Output correction means (sensitivity correction means)
a: Air g: Gas (measuring object)

Claims (4)

A measuring device configured to install a sensor element that outputs an output signal according to a state of a measurement target, and to detect the state of the measurement target based on the output signal of the sensor element,
Cumulative usage time deriving means for accumulating the usage time of the sensor element to derive the cumulative usage time;
Sensitivity correction means for correcting the sensitivity of the sensor element based on the cumulative use time of the sensor element derived by the cumulative use time deriving means;
Temperature deriving means for deriving the temperature of the sensor element;
The cumulative usage time deriving unit is configured to derive the cumulative usage time by accumulating a temperature corrected usage time obtained by correcting the usage time of the sensor element according to the temperature of the sensor element derived by the temperature deriving unit. Measuring device.   The accumulated usage time deriving unit adds the temperature influence coefficient calculated by the Arrhenius rule or the 10 ° C. double rule using the temperature of the sensor element to the usage time of the sensor element to obtain the temperature corrected usage time. The measuring device according to claim 1. The fluid flowing through the measurement channel is the measurement target,
On the upstream side and the downstream side of the measurement channel, a pair of ultrasonic transmitters / receivers capable of transmitting / receiving ultrasonic waves to each other are installed as the sensor elements,
The ultrasonic wave transmitted from one side of the pair of ultrasonic transceivers is received on the other side, and the reception time of the ultrasonic wave of the ultrasonic transceiver is determined by the received signal and the reference voltage of the ultrasonic transceiver. Propagation time measuring means for determining by comparison and measuring the propagation time of ultrasonic waves between the pair of ultrasonic transceivers;
The ultrasonic meter device according to claim 1 or 2, further comprising: a flow velocity value calculating means for deriving a flow velocity value relating to a flow velocity of the fluid flowing through the measurement flow path based on a measurement result of the propagation time measuring means. The measuring device described. A specific component present in the measurement channel
In the measurement channel, a gas detection element whose electrical resistance changes in response to the specific component is disposed as the sensor element,
A heater for heating the gas detection element;
3. The gas detection device according to claim 1, further comprising: a gas detection unit that determines the presence or concentration of the specific component based on an output voltage that changes in accordance with a change in electric resistance of the gas detection element. The measuring device described.

Images