JP2002136595A - Respiratory flow meter - Google Patents

Abstract

(57) [Problem] To provide a respiratory flow meter useful for a device using a mouthpiece such as an artificial respirator or an anesthesia machine. SOLUTION: A first flow path 52 through which respiratory air flows, and a first flow path 52,
Mouthpiece having a second flow path 53 branched from the first flow path 52 and passing only inhalation, and a third flow path 54 branched from the first flow path 52 and passing only expiration 51, a first flow rate sensor 57 provided in the second flow path 52 for detecting the amount of inspired air, and a second flow rate sensor 58 provided in the third flow path 54 for detecting the expiration amount. Consists of

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a respiratory flow meter suitable for a device using a mouthpiece, such as an artificial respirator and an anesthesia machine.

[0002]

2. Description of the Related Art Hitherto, a flow sensor has been used for checking the oxygen inhalation concentration according to the condition of a patient in a respirator and checking the degree of absorption of anesthetic gas during anesthesia by an anesthesia machine.

[0003] In respiratory management in a ventilator (for the mouth), a sensor usually used is inserted between a mouthpiece and a flexible tube connecting the main body of the ventilator to the mouthpiece. Large), heavy,
It can be used only to temporarily set it up when you want to use it and check the condition of the patient. Further, it is necessary to replace the contact part with the human body for each patient, but replacement parts are expensive. Therefore, even if the replacement part is expensive, it must be used for emergency breathing management. However, even if it is desired to use it for normal breathing management on a daily basis, it is difficult to use because it is expensive.

In some cases, it is desired to observe the state of respiration in real time. However, since different types of sensors are used on the exhalation side and the inspiration side, observation waveforms are different, and it is troublesome to determine the respiration state. It is.

On the other hand, a recent anesthesia machine is functionally the same as a respiratory organ, and thus requires the above-mentioned sensor. However, the parameters required for the anesthesia machine include the entry of an anesthetic gas (in, sebo, etc.). There is a concentration control for outflow. Currently,
Expensive and dirt-sensitive infrared spectroscopy sensors are placed in the anesthesia machine, and used while performing maintenance such as cleaning.
Such a sensor can be placed in the breathing circuit,
If it is cheap, it can be used in a disposable.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a respiratory flow meter useful for a device using a mouthpiece such as a ventilator or an anesthesia machine in view of the above-mentioned problems. is there.

[0007]

In view of the above-mentioned object,
The respiratory flow meter according to the first aspect of the present invention has a first flow path through which respiratory air flows, a second flow path branched from the first flow path, and passing only inspired air, and a first flow path. A mouthpiece provided with a third flow passage branched from the road and passing only expiration, a first flow sensor provided in the second flow passage for detecting an inspired air volume, and a third flow passage A second flow sensor is provided in the road and detects the amount of expiration.

According to the first aspect of the present invention, a respiratory flow meter according to the present invention has a first flow path through which respiratory air flows and a second flow path branched from the first flow path to allow only the inhalation to pass. A mouthpiece having a third flow path branched from the first flow path and passing only expiration, and a first mouthpiece provided in the second flow path and configured to detect the amount of inhaled air. And a second flow sensor provided in the third flow path and detecting the expiratory volume.

According to a second aspect of the present invention, in the respiratory flow meter according to the first aspect, the first and second flow sensors detect inhalation or expiration flowing through the second or third flow path. A heater for heating, an upstream temperature sensor arranged upstream of the heater for inhalation or expiration to detect a temperature of inhalation or expiration and outputting a first temperature detection signal; A downstream temperature sensor that is disposed downstream of the exhalation and detects a temperature of inhalation or expiration and outputs a second temperature detection signal; and a support substrate that supports the heater, the upstream temperature sensor, and the downstream temperature sensor. And a flow sensor comprising:

According to the second aspect of the present invention, the first and second flow sensors have a heater for heating the intake or expiration flowing through the second or third flow path, and a heater for inhaling or exhaling the heater. An upstream temperature sensor that is disposed on the upstream side and detects the temperature of inhalation or expiration and outputs a first temperature detection signal; and an upstream temperature sensor that is disposed on the downstream side of inspiration or expiration with respect to the heater and detects the temperature of inspiration or expiration And a flow sensor including a heater, an upstream temperature sensor, and a support substrate that supports the downstream temperature sensor.

According to a third aspect of the present invention, there is provided a respiratory flow meter having a first flow path through which respiratory air flows, and a second flow path branched from the first flow path and passing only inspired air. A mouthpiece having a third flow passage branched from the first flow passage and passing only exhaled air, and a mouthpiece provided in the second flow passage for detecting the amount of inspired gas and the type of gas contained in inspired air First
A flow rate and gas type sensor, and a second sensor provided in the third flow path for detecting an expiration amount and a gas type contained in the expiration.
And a gas type sensor.

According to the third aspect of the present invention, a respiratory flow meter according to the present invention has a first flow passage through which respiratory air flows, and a second flow passage branched from the first flow passage and allowing only the inhalation to pass therethrough. And a mouthpiece provided with a third flow passage branched from the first flow passage and passing only expiration, and a mouthpiece provided in the second flow passage and included in the inspired air volume and the inspired air The sensor comprises a first flow rate and gas type sensor for detecting a gas type, and a second flow rate and gas type sensor provided in the third flow path for detecting an exhalation amount and a gas type contained in the exhalation.

According to a fourth aspect of the present invention, in the respiratory flow meter according to the third aspect, the first and second flow rate and gas type sensors are provided for inhaling air flowing through the second or third flow path. Or a heater for heating expiration, an upstream temperature sensor disposed upstream of inhalation or expiration with respect to the heater, and detecting a temperature of inspiration or expiration and outputting a first temperature detection signal; A downstream temperature sensor that is disposed downstream of inspiration or expiration and detects the temperature of inspiration or expiration and outputs a second temperature detection signal; and a heater that is substantially perpendicular to the flow direction of inspiration or expiration with respect to the heater. A lateral temperature sensor that is disposed and detects a temperature of inhalation or expiration and outputs a third temperature detection signal; and supports the heater, the upstream temperature sensor, the downstream temperature sensor, and the lateral temperature sensor. It consists of one chip type flow sensor comprising a supporting substrate and said.

According to the fourth aspect of the present invention, the first and second flow rate and gas type sensors include a heater for heating intake air or expiration flowing through the second or third flow path, and an intake air for the heater. Or, an upstream temperature sensor that is arranged on the upstream side of exhalation and detects the temperature of inspiration or expiration and outputs a first temperature detection signal, and is disposed on the downstream side of inspiration or expiration with respect to the heater, The temperature is detected and the second
A downstream temperature sensor that outputs a temperature detection signal, and a lateral temperature that is arranged in a direction substantially perpendicular to the flow direction of the intake or expiration with respect to the heater, detects the temperature of the intake or exhalation, and outputs a third temperature detection signal. The sensor comprises a one-chip type flow sensor including a sensor, a heater, an upstream temperature sensor, a downstream temperature sensor, and a support substrate that supports the lateral temperature sensor.

According to a fifth aspect of the present invention, there is provided the respiratory flow meter according to the third aspect, wherein the first and second flow rate and gas type sensors are provided in the second or third flow path. Or a heater for heating expiration, an upstream temperature sensor disposed upstream of inhalation or expiration with respect to the heater, and detecting a temperature of inspiration or expiration and outputting a first temperature detection signal; And a downstream temperature sensor that is disposed downstream of inhalation or expiration and detects the temperature of inspiration or expiration and outputs a second temperature detection signal, and supports the heater, the upstream temperature sensor, and the downstream temperature sensor. A first flow sensor comprising a supporting substrate to be heated, a heater for heating intake air or expiration flowing through the second or third flow path, and a flow direction substantially parallel to the flow direction of intake or expiration on both sides of the heater. The first and / or second temperature sensors are disposed in the direction, detect the temperature of inhalation or expiration and output a third temperature detection signal, and support the heater and the first and / or second temperature sensors. A two-chip type flow sensor including a second flow sensor comprising a supporting substrate to be formed.

According to the fifth aspect of the present invention, the first and second flow rate and gas type sensors include a heater for heating intake air or expiration flowing through the second or third flow path, and an intake air for the heater. Or, an upstream temperature sensor that is arranged on the upstream side of exhalation and detects the temperature of inspiration or expiration and outputs a first temperature detection signal, and is disposed on the downstream side of inspiration or expiration with respect to the heater, The temperature is detected and the second
A downstream temperature sensor that outputs a temperature detection signal, a heater,
A first flow sensor including an upstream temperature sensor and a support substrate supporting the downstream temperature sensor; a heater for heating intake air or expiration flowing through the second or third flow path; It is arranged in a direction substantially perpendicular to the flow direction of expiration, and detects the temperature of inhalation or expiration to obtain
Two-chip type flow including a first and / or second temperature sensor that outputs a temperature detection signal, and a second flow sensor including a heater and a support substrate that supports the first and / or second temperature sensor Consists of sensors.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of a respiratory flow meter according to the present invention. In FIG. 1, a respiratory flow meter includes a first flow path 52 through which respiratory air flows, and a first flow path 5.
A mouthpiece 51 having a second flow path 53 branched from the first flow path 2 and passing only inhaled air, and a third flow path 54 branched and formed from the first flow path 52 and passing only expiration.
It has. First, second and third of mouthpiece 51
Are formed, for example, in a shape in which pipes are connected in a substantially Y-shape.

The first flow path 52 of the mouthpiece 51 is inserted into the mouth of the patient 50, and the second flow path 53 is connected to an inspiratory valve 66 of a respirator 65 through a flexible tube 63. Is connected to an exhalation valve 67 of a ventilator 65 via a flexible tube 64.

An elastic valve 55 that opens only when the patient inhales is provided near the connection port with the flexible tube 63 in the second flow path 53, and the elastic valve 55 is provided downstream of the elastic valve 55. A sensor 57 for measuring the intake air that has passed is provided.
The sensor 57 is used to detect a first intake air amount, as will be described later.
Or a flow sensor serving as a first flow rate and gas type sensor for detecting the amount of intake air and the type of gas contained in the intake air.

An elastic valve 56 that opens only when the patient exhales is provided near the connection with the first flow path 52 in the third flow path 54, and on the downstream side of the elastic valve 56, A sensor 58 for measuring the expiration that has passed through the elastic valve 56 is provided. The sensor 58 has the same configuration as the sensor 57,
As will be described later, a first flow sensor for detecting the intake air amount,
Alternatively, it is a flow sensor that functions as a first flow rate and gas type sensor for detecting the amount of intake air and the type of gas contained in the intake air.

The ventilator 65 includes a flow rate calculation section 68 and a display section 69 in addition to the intake valve 66 and the expiration valve 67. The flow rate calculation unit 68 includes a sensor 57,
58 is connected via cables 59 and 60, one-touch connector 61 and cable 62.

In the above configuration, when the patient 50 breathes while the first flow path 52 of the mouthpiece 51 is inserted into the mouth of the patient 50, the inspired air flowing through the second flow path 53 hits the flow sensor 57. , A detection signal corresponding to the amount of inspired air is generated from the sensor 57, and is supplied to the flow calculator 68 of the ventilator 65 via the cables 59 and 60, the one-touch connector 61 and the cable 62. Similarly, patient 50
When breathing, the exhaled air flowing through the third flow path 54 hits the flow sensor 58, and the sensor 58 generates a detection signal corresponding to the exhaled air volume, and performs artificial respiration via the cables 59 and 60, the one-touch connector 61 and the cable 62. Bowl 65
Is supplied to the flow rate calculation unit 68.

The flow rate calculator 68 includes flow sensors 57 and 5
8 to generate a display signal indicating the inspiratory volume and the expiratory volume, and supply the display signal to the display unit 69. The display unit 69 displays the respiratory volume of the patient 50, and can manage the respiration of the patient 50.

When the necessity of breathing management of the patient 50 is eliminated, the mouthpiece 51 is disconnected from the flexible tubes 63 and 64, and furthermore, the one-touch connector 61 is disconnected from the cables 57 and 58 and the cable 62. , Can be disposable.

As described above, since the flow sensors 57 and 58 and the cables 57 and 58 are only integrated in the mouthpiece 51, the mouthpiece 51 is lightweight and compact, and can be disposable or used all the time. In addition, since both inspiration and expiration can be detected, disordered breathing can be managed in real time. Moreover, since the flow sensors on the intake side and the expiration side have the same configuration, it is easy to observe the waveform of the detection signal.

Next, an example of a flow sensor suitable for use as the flow sensors 57, 58 of the respiratory flow meter of FIG. 1 will be described with reference to the drawings shown in FIGS. In this example, a one-chip type flow sensor 1 serving as a flow rate and gas type sensor capable of detecting the amount of inhalation or exhalation (hereinafter referred to as gas) and the type of gas contained in inspiration or exhalation will be described.

FIG. 2 is a schematic diagram showing a flow rate and gas type which can be detected.
1 is a schematic diagram illustrating a schematic configuration of a chip type flow sensor 1. The micro flow sensor 1 is provided on the inner wall of the second flow path 53 (or the third flow path 54) shown in a cross section in FIG. The micro flow sensor 1 includes a micro heater 4 formed on a Si substrate 2, a downstream thermopile 5 formed downstream of the micro heater 4, and an upstream thermopile 8 formed upstream of the micro heater 4. When,
Right and left thermopiles 11, 1 arranged on both sides of the micro-heater 4 in a direction substantially perpendicular to the gas flow direction (X direction) and detecting the physical property value of the gas and outputting a temperature detection signal.
3 is provided.

As will be described in detail below, the downstream thermopile 5 and the upstream thermopile 8 help to detect the flow rate, and the right thermopile 11 and the left thermopile 13 help to detect the gas type.

FIGS. 3 and 4 are a configuration diagram and a sectional view of the microflow sensor of FIG. In FIG. 3, a micro flow sensor 1 includes a Si substrate 2, a diaphragm 3, a micro heater 4 formed of platinum or the like formed on the diaphragm 3, and a downstream thermopile 5 formed on the diaphragm 3 downstream of the micro heater 4. Power supply terminals 6A and 6B for supplying a drive current from a power supply (not shown) to the microheater 4, an upstream thermopile 8 formed on the diaphragm 3 upstream of the microheater 4, and a first temperature output from the upstream thermopile 8 First output terminals 9A and 9B for outputting a detection signal, and a second output terminal 7 for outputting a second temperature detection signal output from the downstream thermopile 5
A, 7B. The downstream thermopile 5 and the upstream thermopile 8 constitute a temperature sensor.

The micro flow sensor 1 is disposed in a direction substantially perpendicular to the gas flow direction (the direction from arrow P to arrow Q in FIG. 3) with respect to the micro heater 4, and detects the physical property value of the gas. The right thermopile 11 for outputting the right temperature detection signal (corresponding to the third temperature detection signal), the third output terminals 12A and 12B for outputting the right temperature detection signal output from the right thermopile 11, and the micro heater 4 Arranged in a direction substantially perpendicular to the gas flow direction,
A left thermopile 13 for detecting a physical property value of the gas and outputting a left temperature detection signal (corresponding to a third temperature detection signal); a fourth output terminal 14A for outputting a left temperature detection signal output from the left thermopile 13; 14B, resistors 15 and 16 for obtaining a gas temperature, and output terminals 17A and 17B for outputting gas temperature signals from the resistors 15 and 16. The right thermopile 11 and the left thermopile 13 constitute a temperature sensor.

The upstream thermopile 8, the downstream thermopile 5, the right thermopile 11, and the left thermopile 1
Reference numeral 3 includes a thermocouple. This thermocouple is p ++
-Composed of Si and Al, having a cold junction and a hot junction, detecting heat, and generating a thermoelectromotive force from a temperature difference between the cold junction and the hot junction to output a temperature detection signal. Has become.

As shown in FIG. 4, a diaphragm 3 is formed on the Si substrate 2. The diaphragm 3 has a micro heater 4, an upstream thermopile 8,
Each hot junction of the downstream thermopile 5, the right thermopile 11, and the left thermopile 13 is formed.

According to the micro flow sensor 1 configured as described above, when the micro heater 4 starts heating by an external drive current, the heat generated from the micro heater 4 is converted into a downstream thermopile using gas as a medium. 5 and the upstream thermopile 8 are transmitted to the respective hot junctions. The cold junction of each thermopile is a Si substrate (S
i.sub. substrate), the temperature is the substrate temperature. Each hot junction is on the diaphragm, so it is heated by the transmitted heat, and its temperature rises above the Si substrate temperature.
Each thermopile generates a thermoelectromotive force based on the temperature difference between the hot junction and the cold junction, and outputs a temperature detection signal.

The heat transmitted by using the gas as a medium is transmitted to each thermopile by a synergistic effect of a thermal diffusion effect of the gas and a flow velocity of the gas flowing from P to Q. That is, when there is no flow velocity, the heat is uniformly transmitted to the upstream thermopile 8 and the downstream thermopile 5 by thermal diffusion, and the first temperature detection signal from the upstream thermopile 8 and the second temperature detection signal from the downstream thermopile 5 Is zero.

On the other hand, when a flow velocity is generated in the gas, the amount of heat transmitted to the hot junction of the upstream thermopile 8 increases due to the flow velocity, and the difference signal between the second temperature detection signal and the first temperature detection signal is reduced to the flow velocity. It will be a corresponding positive value.

On the other hand, when the micro-heater 4 starts heating by an external driving current, the heat generated from the micro-heater 4 is supplied to the micro-heater 4 only by the heat diffusion effect of the gas without being affected by the gas flow velocity. Right thermopile 11 arranged in a direction substantially perpendicular to the gas flow direction
Is transmitted to In addition, the left thermopile 1 disposed in the direction substantially perpendicular to the gas flow direction with respect to the micro heater 4.
Similar heat is transmitted to the third. Therefore, the third output terminals 12A and 12B are generated by the electromotive force of the right thermopile 11.
The fourth output terminal 14A, due to the right temperature detection signal output from the
Based on the left-side temperature detection signal output from 14B, it is possible to calculate physical properties of the gas such as a heat diffusion constant determined by heat conduction, heat diffusion, specific heat and the like.

Further, according to the micro flow sensor 1, since the micro heater 4, the upstream thermopile 8, the downstream thermopile 5, the right thermopile 11, and the left thermopile 13 are formed on the diaphragm 3, the heat capacity thereof is reduced. Thus, power consumption can be reduced. In addition, since the configuration of the micro flow sensor 1 is simple, there is an effect that it can be manufactured at low cost.

Next, a description will be given of a flow meter using the above-mentioned micro flow sensor 1 which can always accurately measure the gas flow rate regardless of the type or composition of the gas regardless of the change. .

FIG. 5 is a block diagram showing the construction of a flow meter using the micro flow sensor 1 shown in FIGS. This flow meter corresponds to the flow calculation unit 68 of the respirator 65 in FIG. 1, and detects the second temperature detection signal from the downstream thermopile 5 in the microflow sensor 1 and the upstream thermopile 8 in the microflow sensor 1. Amplifier 33a for amplifying the difference signal from the first temperature detection signal from the first thermo-pile, amplifier 35a for amplifying the right temperature detection signal from the right thermo-pile 11 in the micro flow sensor 1, and the left thermo pile in the micro flow sensor 1. It comprises an amplifier 35b for amplifying the left-side temperature detection signal from 13 and a microcomputer 40.

The microcomputer 40 includes an amplifier 35
a adding section 45 for adding the right-side temperature detection signal from the amplifier a to the left-side temperature detection signal from the amplifier 35b;
A dividing unit 47 for dividing the difference signal between the second temperature detection signal and the first temperature detection signal obtained by the above by the addition signal output from the addition unit 45, and the flow rate of the gas based on the division signal output from the division unit 47 And a fluid property value calculation section 43 for calculating property values such as heat conductivity, specific heat, viscosity, and density of the gas based on the addition signal output from the addition section 45. .

Next, a flow rate measuring method realized by the flow meter of FIG. 5 will be described with reference to a flowchart shown in FIG.

First, the micro heater 4 is heated by a driving current based on a pulse signal from the outside (step S1).
1), a second temperature detection signal is output from the downstream thermopile 5, and a first temperature detection signal is output from the upstream thermopile 8 (step S13). The second temperature detection signal is output to the differential amplifier 33, and the first temperature detection signal is output to the differential amplifier 33. FIG. 7 shows the response of the first temperature detection signal and the second temperature detection signal to the pulse signal.

Next, the differential amplifier 33 receives the second temperature detection signal from the downstream thermopile 5 and the upstream thermopile 8
The difference signal from the first temperature detection signal is amplified (step S15).

The adder 45 adds the right-side temperature detection signal from the amplifier 35a and the left-side temperature detection signal from the amplifier 35b to obtain an addition signal (step S17).
FIG. 8 shows a timing chart of the right temperature detection signal, the left temperature detection signal, and the addition signal. Next, the division unit 47
Obtains a divided signal by dividing the amplified difference signal obtained in step S15 by the addition signal obtained in step S17 (step S19).

Subsequently, the flow rate calculating section 41 determines in step S1
The accurate flow rate of the gas is calculated based on the division signal obtained in step 9 (step S21). Further, the fluid property value calculation unit 4
3 is the sum of the addition signal obtained in step S17 and step S17.
Based on the accurate flow rate of the gas calculated in step 21, the physical properties of the gas, such as the thermal conductivity, specific heat, viscosity, and density of the gas, are calculated (step S23).

As described above, the right thermopile 11 and the left thermopile 13 arranged in the direction perpendicular to the gas flow direction detect the physical properties of the gas to measure the thermal conductivity of the gas. Become. When the flow velocity of the gas is zero, the speed at which heat is transmitted by the gas depends on the thermal conductivity and the thermal diffusion constant (one of the physical properties of the gas) determined by thermal diffusion, specific heat, and the like. When the flow velocity is zero, the thermal diffusion constant is obtained from the temperature difference between the right thermopile 11, the left thermopile 13, and the microheater 4. The larger the temperature difference, the smaller the thermal diffusion constant.

The magnitude of the thermal diffusion constant also affects the first temperature detection signal output by the upstream thermopile 8 and the second temperature detection signal output by the downstream thermopile 5, and these values are used to determine the magnitude of the thermal diffusion constant. It changes according to. Therefore,
In principle, the first temperature detection signal and the second temperature detection signal are
Alternatively, by dividing these differences by the thermal diffusion constant, an accurate flow rate can be calculated even for gases having different thermal diffusion constants, that is, for any kind of gas.

On the other hand, when the flow rate is not zero, heat is carried downstream by the gas flow, and the amount of heat reaching the right thermopile 11 and the left thermopile 13 is
It decreases with it. That is, the heat diffusion around the right thermopile 11 and the left thermopile 13 is increased by the gas flow. Here, it is generally known that the rate of increase of the thermal diffusion is proportional to the square root of the flow velocity of the gas, and in principle, the thermal diffusion constant of the gas is such that even if the flow rate of the gas is known in some way, In this case, it can be estimated at any flow rate.

On the other hand, also around the upstream thermopile 8 and the downstream thermopile 5, an increase in heat diffusion due to the gas flow, similar to that around the right thermopile 11 and the left thermopile 13 (decrease in the amount of heat transferred from the micro heater 4). When the flow rate of the gas increases, the difference between the temperature of the gas around the downstream thermopile 5 and the temperature of the gas around the upstream thermopile 8 decreases due to the increase in thermal diffusion accompanying the gas flow.

For this reason, the difference between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8, which should normally increase in proportion to the increase in the gas flow velocity. If the signal becomes smaller due to the increase in heat diffusion and the flow rate of the gas becomes too large, the decrease due to the increase in heat diffusion exceeds the increase due to the increase in flow velocity, and the signal increases despite the increase in flow rate. The difference signal between the second temperature detection signal and the first temperature detection signal may decrease.

Therefore, when the flow rate is zero, the added value of the right temperature detection signal output by the right thermopile 11 and the left temperature detection signal output by the left thermopile 13 is considered to be "1", and The ratio of the added value of the right temperature detection signal and the left temperature detection signal in the case of there is imitated as a coefficient representing the rate of change of the amount of moving heat, this coefficient,
An operation of multiplying a difference signal between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8 is performed.

That is, by dividing the difference signal between the second temperature detection signal and the first temperature detection signal by the sum of the right temperature detection signal and the left temperature detection signal, the flow rate excluding the influence of the heat diffusion change is eliminated. Calculation becomes possible, and an accurate and high-resolution flow rate can be obtained.

In the above-described embodiment, the amplified difference signal between the second temperature detection signal from the downstream thermopile 5 obtained from the differential amplifier 33 and the first temperature detection signal from the upstream thermopile 8 is used. In the divider 47, the influence of the change in heat diffusion is eliminated by dividing the right-side temperature detection signal from the amplifier 35a and the left-side temperature detection signal from the amplifier 35b by an addition signal obtained by the addition unit 45. The flow rate can be calculated.

In the above embodiment, the dividing unit 4
7 is performed prior to the calculation of the flow rate by the flow rate calculation unit 41. This is because of the thermal diffusion that appears in the amplified difference signal between the second temperature detection signal and the first temperature detection signal. This is because, in order to eliminate the influence of the change, it is not necessary to grasp the physical properties of the gas as strictly accurate values such as thermal conductivity, specific heat, viscosity, and density.

That is, in the above-described embodiment, the fluid physical property value calculator 43 calculates the thermal conductivity, specific heat, viscosity, and density of a gas that cannot be specified unless the state of thermal diffusion is understood with high precision. The accurate flow rate of the gas excluding the influence of the change in heat diffusion is calculated in advance by the flow rate calculation unit 41, and this is reflected in the calculation of the physical property value by the fluid property value calculation unit 43.

However, the fluid property value calculation unit 4
Depending on the type of the factor calculated in step 3, the physical property value is calculated in advance by the fluid property value calculating unit 43, and the second temperature detection signal from the downstream thermopile 5 from the differential amplifier 33 and from this. Based on the amplified difference signal from the first temperature detection signal from the upstream thermopile 8 and the amplified temperature difference signal, the accurate flow rate of the gas excluding the influence of the change in heat diffusion may be calculated later.

As described above, according to the above-described flow meter, the right thermopile 11 and the left thermopile 13 are arranged in the direction substantially perpendicular to the gas flow direction with respect to the microheater 4, and the right temperature detection signal and the left temperature detection signal are provided. Is output, the physical property values of the gas such as the thermal diffusion constant can be accurately calculated based on the right temperature detection signal and the left temperature detection signal without being affected by the gas flow direction. The type of gas can be specified.

Since the gas flow rate calculated by the flow rate calculation section 41 is corrected based on the calculated physical properties of the gas, the type and composition of the gas are changed without any special measures. Even in this case, the flow rate can be accurately measured.

Therefore, referring again to FIG. 1, when the flow sensors 57 and 58 capable of detecting the flow rate and the gas type described with reference to FIGS. It is possible to grasp the kind of gas contained in the gas. Therefore, in such a case,
The mouthpiece 51 can be used in an anesthesia machine (not shown) instead of the respirator 65, and the amount of anesthetic gas absorbed by a patient can be determined by gas type determination.

As described above, the embodiment of the present invention has been described. However, the present invention is not limited to this, and various modifications and applications are possible.

For example, in the present invention, since the flow rate calculation unit is not integrated with the mouthpiece with the sensor but is formed separately, the configuration of the flow rate calculation unit can be freely designed. A warning function can be added to notify an alarm when the value exceeds a predetermined amount.

The flow sensors 57 and 58 shown in FIG.
Since the micro flow sensor described with reference to FIGS. 8A and 8B is used, the gas flow is determined based on the polarity inversion of the difference signal between the second temperature detection signal from the downstream thermopile 5 and the first temperature detection signal from the upstream thermopile 8. Direction can be detected, and therefore backflow can also be detected.

As another embodiment of the present invention, a one-chip type micro flow sensor according to the above-described embodiment is used as a flow sensor capable of detecting the flow rate of inhalation or expiration and the type of gas contained in inspiration or expiration. Instead of 1, two-chip type flow sensors 101 and 101 'may be used as shown in FIGS.

FIG. 9 is a flow chart showing the detection of the flow rate and the gas type.
It is a schematic diagram explaining a schematic structure of a chip type flow sensor. Two-chip microflow sensors 101 and 1
01 'is provided on the inner wall of the flow path 53 (or 54) shown in a cross section in FIG.

One micro flow sensor 101 has
Micro heater 104 formed on i-substrate 102
And a downstream thermopile 105 formed on the downstream side of the microheater 104 and an upstream thermopile 108 formed on the upstream side of the microheater 104, and serve to detect a gas flow rate.

The other micro flow sensor 101 ′
Micro heater 10 formed on Si substrate 102 '
4 'and first and second thermopiles 105' which are arranged on both sides of the micro-heater 104 'in a direction substantially perpendicular to the gas flow direction (X direction), and which detect the physical properties of the gas and output a temperature detection signal. , 108 ′ to assist in detecting the type of gas.

FIGS. 10 and 11 are a structural view and a sectional view of the micro flow sensor of FIG. The micro flow sensor 101 is disposed in the gas flow direction (the direction from the solid arrow P to the solid arrow Q), and the Si substrate 10
2. Diaphragm 103, micro heater 104 made of platinum or the like formed on diaphragm 103, downstream thermopile 105 formed on diaphragm 103 downstream of micro heater 104, micro heater 104
Power supply terminal 10 for supplying a drive current from a power supply (not shown)
6A and 6B, an upstream thermopile 108 formed on the diaphragm 103 at the upper end of the micro heater 104, first output terminals 109A and 109B for outputting a first temperature detection signal output from the upstream thermopile 108, and a downstream thermopile 105. And second output terminals 107A and 107B for outputting a second temperature detection signal output from the second output terminal. The downstream thermopile 5 and the upstream thermopile 8 are
Construct a temperature sensor.

The upstream thermopile 108 and the downstream thermopile 105 are composed of thermocouples. This thermocouple is made of p ++-Si and Al, has a cold junction and a hot junction, detects heat, and generates a thermoelectromotive force from a temperature difference between the cold junction and the hot junction, A temperature detection signal is output.

Further, as shown in FIG.
2, a diaphragm 103 is formed, and a hot junction of each of the micro heater 104, the upstream thermopile 108, and the downstream thermopile 105 is formed on the diaphragm 103.

Further, the micro flow sensor 101 ′
Although it has the same structure as the micro flow sensor 101, in FIGS. 10 and 11,
Si substrate 102 ′, diaphragm 103 ′, micro heater 104 ′, and first and second thermopiles 105 ′ and 10 formed on both sides of micro heater 104.
Only 8 'is shown. Micro flow sensor 101 '
Are arranged in the gas flow direction (the direction from the dotted arrow P to the dotted arrow Q) in FIG. 10, and the first and second thermopiles 105 'and 108' constitute a temperature sensor.

According to the micro flow sensor 101 configured as described above, when the micro heater 104 starts heating with an external drive current, the micro heater 1
The heat generated from 04 is transferred to the respective hot junctions of the downstream thermopile 105 and the upstream thermopile 108 using gas as a medium. Since the cold junction of each thermopile is on the Si substrate (Si substrate), it is at the substrate temperature. Since each hot junction is on the diaphragm, it is heated by the transferred heat, and the temperature is lower than the Si substrate temperature. The temperature rises. Each thermopile generates a thermoelectromotive force based on the temperature difference between the hot junction and the cold junction, and outputs a temperature detection signal.

The heat transmitted by using the gas as a medium is transmitted to each thermopile by a synergistic effect of a gas thermal diffusion effect and a flow velocity of the gas flowing from P to Q. That is, when there is no flow velocity, the heat is uniformly transmitted to the upstream thermopile 8 and the downstream thermopile 105 by thermal diffusion, and the first temperature detection signal from the upstream thermopile 108 and the second temperature detection signal from the downstream thermopile 105 Is zero.

On the other hand, when the flow velocity is generated in the gas, the amount of heat transmitted to the hot junction of the upstream thermopile 108 increases due to the flow velocity, and the difference signal between the second temperature detection signal and the first temperature detection signal becomes the flow velocity. It will be a corresponding positive value.

On the other hand, according to the micro flow sensor 101 ′, when the micro heater 104 ′ starts heating by an external driving current, the heat generated from the micro heater 104 ′ is not affected by the gas flow rate, Is transmitted only to the first thermopiles 105 'and 108' arranged on both sides of the micro-heater 104 'in a direction substantially perpendicular to the gas flow direction. For this reason,
Based on the first temperature detection signal output by the electromotive force of the first thermopile 105 'and / or the second temperature detection signal output by the electromotive force of the second thermopile 108', heat conduction and heat diffusion are performed. , The physical properties of the gas such as the thermal diffusion constant determined by the specific heat and the like can be calculated.

Next, the micro flow sensor 10 described above is used.
1 and 101 ', a flow meter that can always accurately measure the gas flow rate regardless of the type or composition of the gas, will be described.

FIG. 12 is a block diagram showing the construction of a flow meter using the micro flow sensor shown in FIGS. This flow meter corresponds to the flow calculation unit 65 of the respirator 65 in FIG. 1, and detects a temperature detection signal from a downstream thermopile 105 in the microflow sensor 101 and an upstream thermopile 108 in the microflow sensor 101.
Amplifier 3 amplifies the difference signal from the temperature detection signal from
And an amplifier 3 for amplifying a temperature detection signal from the first thermopile 105 'in the micro flow sensor 101'.
5a, an amplifier 35b for amplifying a temperature detection signal from the second thermopile 108 'in the micro flow sensor 101', and a microcomputer 40.

The microcomputer 40 includes an amplifier 35
an adder 45 for adding the temperature detection signal from the amplifier a and the temperature detection signal from the amplifier 35b; a divider 47 for dividing the difference signal obtained by the differential amplifier 33 by the addition signal output from the adder 45; A flow rate calculator 41 for calculating a gas flow rate based on the division signal output from the divider 47;
5, the thermal conductivity and specific heat of the gas,
Fluid physical property calculation unit 43 for calculating physical properties such as viscosity and density
And is provided.

Next, a flow rate measuring method realized by the flow meter of FIG. 12 will be described with reference to a flowchart shown in FIG.

First, when the micro heaters 104 and 104 'are heated by a driving current based on a pulse signal from the outside (step S31), a temperature detection signal is output from the downstream thermopile 105 and the upstream thermopile 108, respectively (step S33). ).

Next, the differential amplifier 33 compares the temperature detection signal from the downstream thermopile 105 with the upstream thermopile 1
Then, the difference signal from the temperature detection signal from step 08 is amplified (step S35).

The adder 45 generates the temperature detection signal from the first thermopile 105 'amplified by the amplifier 35a and the second thermopile 10 amplified by the amplifier 35b.
The temperature detection signal from 8 'is added to obtain an addition signal (step S37). Next, the division unit 47 determines in step S
The amplified difference signal obtained in step S35 is divided by the addition signal obtained in step S37 to obtain a division signal (step S3).
9).

Subsequently, the flow rate calculator 41 determines in step S3
An accurate gas flow rate is calculated based on the division signal obtained in step 9 (step S41). Further, the fluid property value calculation unit 4
3 is the sum of the added signal obtained in step S37 and step S37.
Based on the accurate flow rate of the gas calculated in 41, the physical properties of the gas, such as the thermal conductivity, specific heat, viscosity, and density of the gas, are calculated (step S43).

As described above, according to the flow meters shown in FIGS. 9 to 12, the gas flow rate can be measured by the micro flow sensor 101 and the physical property value of the gas can be calculated by the micro flow sensor 101 '. And therefore the type of gas can be specified.

As a further embodiment, the sensor used in the present invention is not limited to the above-described flow sensor, and a sensor having another configuration may be used. Further, if only the flow rate of expiration or inspiration is measured, the gas type sensor is not necessary and only the flow rate sensor may be used.

As still another example, in the above-described embodiment, sensors are separately arranged on the inhalation side and the expiration side, but one sensor, for example, a flow sensor or a flow sensor, is provided in the first flow path of the mouthpiece. Place flow and gas type sensors,
A single sensor may be used for measurement of both inspiration and expiration flowing through the first flow path.

In the above embodiment, the respirator has been described, but the present invention can be used for other devices using a mouthpiece, such as an anesthesia machine. Therefore, the respiratory flow meter of the present invention, air, oxygen, laughter, carbon dioxide,
Helium, xenon, nitric oxide, carbon monoxide, isoflurane, sevoflurane, etc. are raised. In addition, air, oxygen,
The measurement can be performed by focusing on one component of a mixed gas of laughter, carbon dioxide, helium, xenon, nitric oxide, carbon monoxide, isoflurane, and sevoflurane.

[0088]

According to the first aspect of the present invention, it is lightweight and compact, and can be disposable or constantly used. In addition, since both inspiration and expiration can be detected, disordered breathing can be managed in real time.

According to the second aspect of the present invention, the flow sensor can detect the flow rate of inhalation and expiration and the type of gas contained in inspiration and expiration.

According to the third aspect of the present invention, it is lightweight and compact, and can be disposable or constantly used. In addition, since both inspiration and expiration can be detected, disordered breathing can be managed in real time. In addition, the type of gas contained in the breath can be detected.

According to the fourth aspect of the present invention, the flow rate of inhalation and expiration and the type of gas contained in inspiration and expiration can be detected by the one-chip type flow sensor.

According to the fifth aspect of the present invention, the flow rate of inhalation and expiration and the type of gas contained in inspiration and expiration can be detected by the two-chip type flow sensor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a respiratory flow meter according to the present invention.

FIG. 2 is a schematic diagram illustrating a schematic configuration of a one-chip type micro flow sensor as an example of the flow sensor in FIG.

FIG. 3 is a configuration diagram of the micro flow sensor of FIG. 2;

FIG. 4 is a sectional view of the micro flow sensor of FIG. 2;

FIG. 5 is a configuration block diagram of a flow meter using the micro flow sensor of FIG. 2;

FIG. 6 is a flowchart showing a flow rate measuring method realized by the flow meter of FIG.

FIG. 7 is a diagram showing a first temperature detection signal and a second temperature detection signal.

FIG. 8 is a diagram showing a right temperature detection signal and a left temperature detection signal.

FIG. 9 is a schematic diagram illustrating a schematic configuration of a two-chip type micro flow sensor as another embodiment of the respiratory flow meter in FIG. 1;

FIG. 10 is a configuration diagram of the micro flow sensor of FIG. 9;

FIG. 11 is a sectional view of the micro flow sensor of FIG. 9;

12 is a configuration block diagram of a flow meter using the micro flow sensor of FIG.

FIG. 13 is a flowchart showing a flow rate measuring method realized by the flow meter of FIG.

[Explanation of symbols]

1 1-chip type micro flow sensor (first and second flow rate sensors; first and second flow rate and gas type sensors) 2 Si substrate (supporting substrate) 4 micro heater (heater) 5 downstream thermopile (downstream temperature) 8) Upstream thermopile (upstream temperature sensor) 11 Right thermopile (lateral temperature sensor) 13 Left thermopile (horizontal temperature sensor) 41 Flow rate calculation unit 43 Fluid property value calculation unit 45 Addition unit 47 Division unit 50 Patient 51 mouse Piece 52 First flow path 53 Second flow path 54 Third flow path 57 Sensor (first flow rate sensor; first flow rate and gas type sensor) 58 Sensor (second flow rate sensor; second flow rate) And gas type sensor) 59 cable 60 cable 61 one-touch connector 62 cable 63 coiled tube 64 coiled tube 65 artificial call Suction device 66 Intake valve 67 Expiration valve 68 Flow rate calculation unit 69 Display unit 101 Micro flow sensor (part of a two-chip type flow sensor; first and second flow sensors; one of first and second flow and gas type sensors) Part) 101 'micro flow sensor (part of a two-chip type flow sensor; first and second flow rate sensors; first and second flow rate and gas type sensors) 102 Si substrate (supporting substrate) 102' Si substrate ( Support substrate) 104 Micro heater (heater) 104 'Micro heater (heater) 105 Downstream thermopile (downstream temperature sensor) 105' First thermopile (first temperature sensor) 108 Upstream thermopile (upstream temperature sensor) 108 ′ Second thermopile (second temperature sensor)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01F 1/692 G01F 1/68 104Z (72) Inventor Kazuhiro Ushijima 23 Minamikashima, Futamata-cho, Tenryu City, Shizuoka Prefecture Yazaki Keiki (72) Inventor Kiyoshi Oda 1500 Onjuku, Susono-shi, Shizuoka Prefecture Yazaki Sogyo Co., Ltd. (72) Inventor Mitsuyoshi Anzai 1500 Onjuku, Susono-shi, Shizuoka Prefecture Yazaki Sogyo Co., Ltd.F-term (reference) 2F030 CA10 CC11 2F035 EA08 4C038 SS04 ST00 SU04 SX01 SX02

Claims (5)

[Claims] 1. A first flow path through which respiratory air flows, a second flow path branched from the first flow path, and a second flow path through which only inhalation passes, and a branch flow formed from the first flow path, only expiration A mouthpiece provided with a third flow path through which the air flows, a first flow sensor provided in the second flow path and detecting the amount of inspired air, and an expiration volume provided in the third flow path And a second flow sensor for detecting the following. 2. The heater according to claim 1, wherein the first and second flow rate sensors are arranged on a heater for heating intake air or expiration flowing through the second or third flow path, and are arranged upstream of the heater for intake or expiration. An upstream temperature sensor for detecting the temperature of inhalation or expiration and outputting a first temperature detection signal, and a second temperature sensor disposed downstream of inhalation or expiration with respect to the heater and detecting the temperature of inspiration or expiration. 2. The respirator according to claim 1, further comprising a flow sensor including a downstream temperature sensor that outputs a temperature detection signal, and a support substrate that supports the heater, the upstream temperature sensor, and the downstream temperature sensor. Flowmeter. 3. A first flow path through which respiratory air flows, a second flow path branched from the first flow path, and a second flow path through which only inhalation passes, and a branch flow formed from the first flow path, and only expiration A mouthpiece provided with a third flow path through which air flows, a first flow rate and gas type sensor provided in the second flow path and configured to detect an intake amount and a gas type included in the intake air, And a second flow rate and gas type sensor for detecting the amount of expiration and the type of gas contained in the exhalation. 4. The first and second flow rate and gas type sensors include: a heater for heating intake air or expiration flowing through the second or third flow path; and an upstream side of intake or expiration with respect to the heater. An upstream temperature sensor that detects the temperature of inspiration or expiration and outputs a first temperature detection signal; and an upstream temperature sensor that is disposed downstream of inspiration or expiration with respect to the heater to detect the temperature of inspiration or expiration. A downstream temperature sensor that outputs a second temperature detection signal to the heater, and is disposed in the heater in a direction substantially orthogonal to the flow direction of the intake or expiration to detect the temperature of the intake or expiration and outputs a third temperature detection signal And a one-chip type flow sensor comprising a heater, an upstream temperature sensor, a downstream temperature sensor, and a support substrate that supports the horizontal temperature sensor. Respiratory flow meter according to claim 3, wherein. 5. The first and second flow rate and gas type sensors include: a heater for heating intake air or expiration flowing through the second or third flow path; and an upstream side of intake or expiration with respect to the heater. An upstream temperature sensor that detects the temperature of inspiration or expiration and outputs a first temperature detection signal; and an upstream temperature sensor that is disposed downstream of inspiration or expiration with respect to the heater to detect the temperature of inspiration or expiration. A first flow sensor comprising: a downstream temperature sensor that outputs a second temperature detection signal through the first temperature sensor; and a support substrate that supports the heater, the upstream temperature sensor, and the downstream temperature sensor; A heater for heating the intake air or the expiration flowing through the flow path, and a third temperature detection signal disposed on both sides of the heater in a direction substantially orthogonal to the flow direction of the intake or the expiration for detecting the temperature of the intake or the expiration. First and outputs the /
Or a second temperature sensor, the heater and the first
4. A respiratory flowmeter according to claim 3, comprising a two-chip type flow sensor comprising: a second flow sensor comprising a support substrate for supporting the second temperature sensor.