JP2000046678A - Liquid leakage detection device and chemical filling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the existence or non-existence of liquid leakage with the application of simple constitution. SOLUTION: As a liquid leakage detection method for detecting the leakage of liquid running in a passage 1, electric power is supplied to a thermister 8 laid near the passage 1, and the change of the resistance value of the heated thermister 8 is detected with a resistance value detection part 3. When the variation of the resistance value per specified time is equal to or above a required value, a control circuit 6 identifies that the closure of the passage 1 with a solenoid valve 2 is insufficient and causes an alarm part 7 to output an alarm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid leakage detecting device for detecting liquid leakage of a liquid flowing through a flow path, and a chemical liquid injection device for injecting a chemical liquid into a living body.

[0002]

2. Description of the Related Art In recent years, morphine hydrochloride and the like have been used for the purpose of relieving pain in patients with terminal cancer, and a portable liquid injector for injecting a liquid by operating the patient himself when the patient feels pain. Is used. This device requires a mechanism for opening and closing the injection channel of the chemical solution in order to inject the chemical solution intermittently. As such a mechanism, for example, a method of opening and closing with a valve using electromagnetic force is used, but when an abnormality occurs in the valve and the flow path is not sufficiently closed, a drug solution in a living body more than necessary is necessary. It is possible that it is administered incorrectly. In addition, it is conceivable that a bodily fluid may flow backward from the living body to the drug solution side due to such an abnormality of the valve, which is a serious problem in terms of safety.

[0003]

In order to cope with these problems, doctors and nurses have periodically inspected the state of the flow path visually to detect abnormalities. In addition, as means for automatically detecting abnormality of the valve, using a flow meter or the like,
Although it is conceivable to constantly monitor the flow of the liquid in the flow path, the flow meter is provided with a conversion means for converting signals obtained from various sensors into a flow rate value, and its configuration is complicated and expensive. Therefore, there has been a need for a drug solution injector having means for easily detecting whether the injection channel for the drug solution has been reliably closed.

The present invention has been made in view of the above conventional example, and has as its object to provide a liquid leakage detection device and a chemical liquid injection device capable of accurately detecting the presence or absence of liquid leakage with a simple configuration.

It is another object of the present invention to provide a liquid leakage detecting device and a liquid injector capable of detecting liquid leakage at low cost and issuing a warning when the liquid leakage can be detected.

[0006]

In order to achieve the above object, a liquid leakage detecting device according to the present invention has the following arrangement. That is, a liquid leakage detection device that detects liquid leakage of a liquid flowing through a flow path, heating means for supplying heat to a heat-sensitive element disposed near the flow path to heat the heat-sensitive element, and heating by the heating means. Detecting means for detecting a change in the resistance value of the heat-sensitive element, and when the amount of change in the resistance value detected by the detecting means per predetermined time is equal to or more than a predetermined amount, the liquid leaks from the flow path. And a judging means for judging.

[0007] In order to achieve the above-mentioned object, a drug solution injector of the present invention has the following configuration. That is, a drug solution injection device for injecting a drug solution contained in a drug solution bag into a living body, a drug solution path for introducing a drug solution discharged from the drug solution bag into the living body, and the drug solution provided in the drug solution channel. Opening / closing means for opening / closing a passage; heating means for heating the thermosensitive element by energizing a thermosensitive element disposed near the chemical liquid passage; and detecting a change in the resistance value of the thermosensitive element heated by the heating means. It has a detecting means and a judging means for judging that the opening / closing means is abnormal when an amount of change in the resistance value detected by the detecting means per predetermined time is equal to or more than a predetermined amount.

The liquid leakage abnormality that can be detected by the present invention includes a case where the valve is abnormal, a case where the flow path is abnormal (for example, a hole is opened), and the like. In addition, when the valve is abnormal, the liquid leakage abnormality flows erroneously downstream of the flow path through the valve (leakage valve), and the liquid leakage abnormality flows backward from the living body through the valve (leakage valve). It is possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, a description will be given of an example of a chemical liquid injection device for injecting a chemical liquid. However, a liquid leakage (fluid movement) detection method according to the present embodiment is other general fluid (for example, flowing through a pipe) Needless to say, the present invention can be applied to the detection of movement and leakage of water and the like.

FIG. 1 is a block diagram showing a configuration of a main part of a drug solution injection device according to the present embodiment.

In FIG. 1, reference numeral 1 denotes a flow path (chemical solution passage) through which a chemical solution discharged from a chemical solution bag (not shown) flows. Pushed out of the bag. 2
Is a solenoid valve, and by opening and closing the valve 2, the liquid medicine in the flow path 1 is supplied to the patient side. Reference numeral 3 denotes a resistance value detection unit that detects a change in the resistance value of the thermistor 8, that is, a temperature change in the thermistor 8, and outputs the detected voltage as a voltage signal. Reference numeral 4 denotes a heating drive unit, which energizes the thermistor 8 to heat the thermistor 8 itself. A valve control circuit 5 controls opening and closing of the solenoid valve 2 based on an instruction from the control circuit 6. Reference numeral 6 denotes a control circuit which includes, for example, a CPU such as a microcomputer and a memory which is accessed by the CPU and stores various data. Reference numeral 6a denotes a timer which counts a predetermined time designated by the CPU, generates an interrupt signal to the CPU when the time has elapsed, and notifies the CPU that the time has elapsed. Reference numeral 7 denotes an alarm unit, which includes, for example, an LED, a piezoelectric buzzer, or the like.

The thermistor 8 is arranged outside the flow path 1,
The change in temperature is output as a change in resistance. Now, the thermistor 8 is heated by the heating drive unit 4 to a temperature higher than the temperature of the chemical solution in the flow path 1. Specifically, when current is caused to flow through the thermistor 8 to generate heat by the resistance of the thermistor 8, If the chemical flows in the path 1, the heat of the thermistor 8 is quickly taken away by the chemical, and the temperature detected by the thermistor 8 rapidly decreases. On the other hand, when the liquid medicine is not flowing in the flow path 1, that is, when the liquid medicine is stagnant, the degree of lowering of the temperature of the thermistor 8 is smaller than when the liquid medicine is flowing.

A threshold value is provided for such a change in resistance due to a decrease in temperature, and when the resistance value exceeds the threshold value, the flow path is not sufficiently closed by the electromagnetic valve 2 and the electromagnetic valve 2 It can be determined that the chemical is flowing out of the flow path 1 through the passage.

Therefore, by utilizing such characteristics, the presence / absence of liquid leakage in the solenoid valve 2 can be detected.

The signal from the thermistor 8 is converted into an appropriate signal by a filter, an amplifier or the like in the resistance detector 3 and output to the control circuit 6. Then, when the resistance value of the thermistor 8 greatly decreases even though the solenoid valve 2 is closed, the control circuit 6 determines that the closed state of the flow path 1 is abnormal, and the alarm unit 7 is abnormal. Is output, and an alarm sound is generated by, for example, a piezoelectric buzzer.

FIG. 2 is a block diagram showing a configuration of the resistance value detecting section 3. As shown in FIG.

In FIG. 2, reference numeral 8 denotes the thermistor described above;
21 is a thermistor for detecting the ambient temperature. 2
3 and 24 are fixed resistors, 22 is a differential amplifier,
The difference voltage of the bridge circuit constituted by the thermistors 8 and 21 and the resistors 23 and 24 is detected, amplified and output to the control circuit 6. Reference numeral 25 denotes a power supply terminal for supplying power for the thermistor. With such a configuration, a change in the resistance value of the thermistor 8 can be detected without the influence of the ambient temperature.

FIG. 3 is a diagram conceptually showing a change in the waveform of an output signal from the thermistor 8, and FIG. 3A shows a state in which the solenoid valve 2 is completely closed. 3
(B) shows a state when the closing by the solenoid valve 2 is not sufficient.

In FIG. 3A, after the solenoid valve 2 is opened at time t1 and the drug solution is injected through the flow path 1 to the patient side,
At time t2, the solenoid valve 2 is closed. Almost at the same time as the closing of the solenoid valve 2, energization of the thermistor 8 by the heating drive unit 4, that is, heating is started. When the thermistor 8 is heated in this way, the resistance value of the thermistor 8 increases, but the heat is taken away by conduction of heat to the chemical solution, so that the temperature of the thermistor 8 starts to gradually decrease, and immediately after the heating, the resistance value ΔR1 After that, the state becomes substantially stable.

On the other hand, as shown in FIG.
Is insufficient, the leakage of the electromagnetic valve 1 causes the chemical to flow in the flow path 1, and thus the heat of the heated thermistor 8 is more greatly released through the chemical. As a result, the amount of decrease in the resistance value of the thermistor 8 is as shown in FIG.
ΔR2 (ΔR2> ΔR1). Therefore, the threshold value is set based on the decrease (ΔR1) in the resistance value of the thermistor 8 when the solenoid valve 2 is completely closed, and
It is determined that there is an abnormality in the closing of the flow path 1 when the resistance value has changed more.

In this embodiment, the abnormal closing of the solenoid valve 2 is determined by the difference between the resistance value of the thermistor 8 immediately after heating the thermistor 8 and the resistance value of the thermistor 8 when the temperature is lowered and stabilized. If it is detected that the solenoid valve 2 is not closed sufficiently, a determination is made based on the differential value of the resistance value, utilizing the fact that the speed of the temperature decrease due to the flow of the liquid and the loss of heat is high, Another index indicating a difference in the temperature change pattern may be used.

FIG. 4 shows a case where the solenoid valve 2 has no leakage.
FIG. 5 is a diagram showing an output signal of the differential amplifier 22 of FIG.
3 illustrates a change in an output signal of the differential amplifier 22 when leakage occurs in the solenoid valve 2. In FIGS. 4 and 5,
The vertical axis shows the differential voltage, and the horizontal axis shows time (second).

In these figures, the time when self-heating is started by applying a voltage to the thermistor 8 is defined as a start time (0 second).
And As is apparent from a comparison between FIG. 4 and FIG. 5, when no leakage occurs in the solenoid valve 2 (FIG. 4), the difference voltage is approximately −0.5 V, while the leakage occurs in the solenoid valve 2. In the generated state (FIG. 5), the voltage falls below the voltage (about -0.5 V) in FIG. 4 in about 2 seconds. Therefore, the threshold value of the differential voltage is set to -0.6 V, and when the voltage falls below the threshold voltage, it is determined that liquid leakage has occurred from the solenoid valve 2. Thus, for example, in the case of FIG. 5, it is determined that liquid leakage from the solenoid valve 2 has occurred approximately 3 seconds after the heating of the thermistor 8 is started, and at that time the operation of the air pump for discharging the chemical solution from the chemical solution bag is performed. Was stopped.

FIG. 6 is a flowchart showing the processing by the control circuit 6 for the chemical solution bag according to the present embodiment.

First, in step S1, the solenoid valve 2 is closed via the valve control circuit 5, and an air pump (not shown) is driven to start feeding a chemical solution from the chemical solution bag. When it is considered that the liquid medicine has been filled in the flow path 1 in this way, the process proceeds to step S3, where the thermistor 8 is energized via the heating drive unit 4 to start heating by the thermistor 8. Next, proceeding to step S4, it is determined whether or not the voltage level of the output signal of the differential amplifier 22 of the resistance value detection unit 3 has become equal to or lower than a predetermined value (for example, threshold voltage: -0.6 V). If not, the process proceeds to step S5, and steps S4 and S5 are executed until the predetermined time elapses. If the output of the differential amplifier 22 does not fall below the threshold voltage even after the predetermined time measured by the timer 6a elapses, Proceeding to step S6, it is determined that the solenoid valve 2 is normal, and the operation proceeds to normal operation.

If the voltage of the thermistor 8 drops below the predetermined voltage in step S4, the operation proceeds to step S7, in which the operation of the air pump is stopped. Then, in step S8, the alarm unit 7 displays a warning or sounds a buzzer or the like. Make an occurrence.

In the above-described embodiment, the heating of the thermistor is started immediately after the solenoid valve 2 is closed. However, the heating may be performed at any time before and after the closing of the solenoid valve 2 unless it is contrary to the gist of the present invention. good.

The arrangement position of the thermistor 2 for measuring the temperature change is arbitrary as long as the temperature of the chemical can be measured.

In the present embodiment, a thermistor is described as an example of a heat-sensitive element. However, other elements having heat-resistance conversion characteristics can be used.

Further, the thermistor 2 has been described as having a characteristic of increasing resistance when the temperature rises.
It is also possible to use one that decreases in resistance when the temperature rises. Although the thermistor is installed outside the flow channel, it may be installed inside the flow channel.

Further, in the above-described embodiment, an alarm mechanism for generating an alarm sound by a piezoelectric buzzer or the like when it is determined that there is an abnormality in the closing of the flow path has been described, but a warning mark is displayed on a liquid crystal display device or the like. It is also possible to attach an alarm unit, for example. Also, when used at the hospital bedside, using wireless or wired communication technology,
By providing a mechanism for notifying a doctor or a nurse of an abnormality as a part of the alarm means, it is possible to quickly deal with the abnormality.

In the present embodiment, use under various conditions, such as the type of drug solution, the concentration, the dose, or which part of the living body is to be injected, is considered depending on the disease or the condition of the patient. These are optional as long as they do not contradict the spirit of the present invention.

As a mechanism for injecting a chemical, there are known a mechanism using electric power as seen in a syringe pump and an infusion pump, and a mechanism for extruding a chemical by gas pressure or the like. Also, as in the case of an infusion, a chemical solution is arranged at a position higher than an injection part into a living body, so that the chemical solution is injected by gravity and naturally dropped.

It is apparent that the mechanism according to the present embodiment can be applied to any chemical liquid injection system as long as it can be arranged in the flow path for feeding liquid.

Further, in the present embodiment, the means for closing the flow path is a valve controlled by a control circuit, but other methods can be used. For example, when the flow path is an elastic tube such as polyisoprene, the flow path can be closed by a mechanism that presses and closes the tube. On the other hand, the flow path can be opened and closed by manually opening and closing the valve without having a means for controlling the valve such as a control circuit. In addition, various methods can be used as a method for closing the flow path, but it is apparent that all of these methods fall within the scope of the present invention.

As described above, according to the present embodiment, by detecting whether or not the flow path for stopping the injection of the chemical solution has been completely closed, excessive injection of the chemical solution or the detection of the biological Of the body fluid can be prevented.

[0037]

As described above, according to the present invention, the presence or absence of liquid leakage can be accurately detected with a simple configuration.

Further, according to the present invention, there is an effect that a liquid leak can be detected at low cost and a warning can be issued when the liquid leak can be detected.

[0039]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a drug solution injection device according to the present embodiment.

FIG. 2 is a circuit diagram illustrating a configuration of a resistance measurement circuit of a thermistor in the chemical liquid injector according to the present embodiment.

FIG. 3 is a diagram illustrating a change in the thermistor resistance when the solenoid valve is normal (A) and when the solenoid valve is not normal (B) in the drug solution injector of the present embodiment.

FIG. 4 is a diagram showing a specific measurement result example when the solenoid valve according to the present embodiment is normal.

FIG. 5 is a diagram showing a specific measurement result example when the solenoid valve according to the present embodiment is not normal;

FIG. 6 is a flowchart showing a process in a control circuit of the drug solution injection device of the present embodiment.

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Claims (8)

[Claims] 1. A liquid leakage detecting device for detecting liquid leakage of a liquid flowing through a flow path, comprising: a heating unit configured to energize a heat-sensitive element disposed near the flow path to heat the heat-sensitive element; Detecting means for detecting a change in the resistance value of the heat-sensitive element heated by the means; and a liquid leaking from the flow path when a change amount of the resistance value detected by the detecting means per predetermined time is equal to or more than a predetermined amount. And a judging means for judging that the liquid has leaked. 2. The liquid leakage detection device according to claim 1, further comprising a valve for controlling discharge of the liquid from the flow path. 3. The liquid leakage detection device according to claim 1, further comprising an alarm unit that issues an alarm when the determination unit determines that the liquid is leaking. 4. The liquid leakage detecting device according to claim 1, wherein the thermosensitive element is a thermistor. 5. A drug solution injection device for injecting a drug solution contained in a drug solution bag into a living body, wherein a drug solution path for introducing a drug solution discharged from the drug solution bag into the living body is provided in the drug solution channel. Opening / closing means for opening and closing the chemical solution path; heating means for energizing a thermal element arranged near the chemical solution path to heat the thermal element; and a change in the resistance value of the thermal element heated by the heating means. Detecting means for detecting the opening / closing means is determined to be abnormal when a change amount of the resistance value detected by the detecting means per predetermined time is equal to or more than a predetermined amount. Liquid injector. 6. The liquid injector according to claim 5, wherein the opening / closing means includes a valve. 7. The chemical liquid injector according to claim 5, further comprising an alarm unit that generates an alarm when the determination unit determines that the liquid is leaking. 8. The liquid injector according to claim 5, wherein the heat-sensitive element is a thermistor.