JP2013059384A - Gas-mixing device and gas-mixing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-mixing device with which the mixing ratio of gases can be changed in a short response time with high accuracy.SOLUTION: The gas-mixing device 10 includes: a plurality of confluent valves 23 which are disposed in parallel to one another, to each of which oxygen and air are supplied and through which the oxygen and the air pass; a plurality of micropumps 24, each of which is disposed downstream of the confluent valve 23 one by one and sends out the mixture gas of the oxygen and the air passing through the confluent valves 23; and a confluent part 25 where the gases sent out from each of the micropumps 24 are confluent downstream of the micropumps 24.

Description

  The present invention relates to a gas mixing device and system used for a breathing assistance device and the like.

  In the medical field, a respiratory assistance device such as a ventilator is used. This breathing assistance device has a controlled ventilation system for patients without spontaneous breathing (general anesthesia, cardiopulmonary resuscitation, and severe patients), and positive pressure (positive pressure) in the respiratory tract according to the patient's spontaneous breathing Assisted Ventilation method to create Assistance, Partial Assist / Control method combining auxiliary ventilation and controlled ventilation, oscillate the gas supplied by the airway at a frequency of 5-40 Hz, 1-2 ml / kg Various systems such as a high frequency oscillation system that realizes a very low tidal volume are adopted.

  In any type of respiratory assistance device, oxygen is supplied to the airway using an oxygen cylinder or the like. Some types of respiratory assistance devices include a gas mixing device that mixes oxygen in an oxygen cylinder with air in the atmosphere (see, for example, Patent Document 1). This gas mixing device changes the mixing ratio of oxygen and air by adjusting the flow rate of oxygen released from the oxygen cylinder.

JP 2004-298554 A

  In such a gas mixing device, a certain amount of response time is required to accurately change the mixing ratio of oxygen and air. However, it is necessary to perform an appropriate treatment without taking time in a medical site related to human life. That is, in the case of the gas mixing device described above, it is necessary that the mixing ratio of oxygen and air can be accurately changed without taking any time. Such a necessity is not limited to a device that mixes oxygen and air, but is common to devices that mix other gases.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a gas mixing apparatus and system that can change the gas mixing ratio with a short response time and high accuracy.

  The above-mentioned object is achieved by the following means based on the earnest research of the present inventors.

  That is, the means for achieving the above object is arranged in parallel to each other, and each of the plurality of merging valves that receives a plurality of types of gas and allows the gas to pass therethrough, and one downstream of each of the plurality of merging valves. A plurality of micropumps that are arranged one by one and send out the gas that has passed through the merging valve; and a merging unit that joins the gases sent from each of the plurality of micropumps downstream of the plurality of micropumps. This is a gas mixing device.

  In the above invention, it is preferable that each of the plurality of merging valves in the gas mixing device that achieves the above object adjusts a ratio of the flow rates of the plurality of types of gases.

  Alternatively, in the above invention, it is preferable that each of the plurality of merging valves in the gas mixing device that achieves the above-mentioned object switches the type of gas to be passed.

  Alternatively, the means for achieving the object includes the gas mixing device and a gas supply unit that supplies a first gas to each of the plurality of merging valves, and the gas supply unit includes the first gas supply unit. A flow rate adjusting valve that adjusts the flow rate of the first gas discharged from one gas supply source, and in the middle of the path from the flow rate adjusting valve to the plurality of merging valves, or at a point branched from the path A gas chamber that is arranged and has an atmosphere port that is open to the atmosphere and that has the first gas introduced therein; and a flow rate that detects the flow rate at the atmosphere port and outputs the detected flow rate as a signal. A gas mixing system comprising: a sensor; and a control unit that receives the signal output from the flow sensor and controls the flow control valve based on the signal.

  According to the present invention, it is possible to obtain an excellent effect that the change of the gas mixing ratio can be performed with a short response time and high accuracy.

(A) It is the schematic which shows the structure of the gas mixing apparatus of 1st Embodiment which concerns on this invention, (B) and (C) are schematic which shows the structure of a confluence | merging valve. (A) is sectional drawing which shows the structural example of a micropump, (B) is a graph which shows the pressure-flow rate line of the micropump. It is a block diagram which shows the hardware constitutions of the control apparatus used with the same gas mixing apparatus. It is a block diagram which shows the function structure of the control apparatus used with the same gas mixing apparatus. It is the schematic which shows the structure of the gas mixing system of 2nd Embodiment which concerns on this invention. It is a block diagram which shows the function structure of the control apparatus used with the same gas mixing system.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1A illustrates the configuration of the gas mixing device 10 according to the first embodiment of the present invention. The gas mixing device 10 is a device that mixes a first gas and a second gas, and constitutes a part of a medical respiratory assistance device (not shown). In the present embodiment, a gas mixing device 10 that mixes oxygen serving as a first gas and air serving as a second gas will be described as an example.

  The gas mixing apparatus 10 includes an oxygen path branching unit 21 that branches a plurality of paths from the oxygen supply source (five in the present embodiment) and a plurality of paths (five in the present embodiment) from the air supply source. The air path branching section 22 that branches into the air path, and the oxygen path branching section 21 and the air path branching section 22 downstream of the air path branching section 22 are supplied with oxygen and air, and a plurality of them (five in the present embodiment, 5). ) And a plurality of (five in the present embodiment) micropumps 24 that are arranged one by one downstream of each of the plurality of merging valves 23 and send out the mixed gas that has passed through the merging valves 23, At the downstream of the plurality of micropumps 24, a merging portion 25 for merging the mixed gas sent from each of the plurality of micropumps 24, and a control unit 14 for overall control of the entire apparatus (FIG. 3). And called reference 4), and a.

  The type of the merging valve 23 is not particularly limited, but a rotary valve can be adopted as a valve for adjusting the ratio of the flow rate of oxygen and air. Specifically, as shown in FIGS. 1B and 1C, the merging valve 23 includes a rotating body 23a. The merging valve 23 changes the oxygen path width Wo and the air path width Wa by rotating the rotating body 23a.

  Since the plurality of micropumps 24 are arranged in parallel to each other, the total flow rate of the mixed gas delivered from the plurality of micropumps 24 is proportional to the number of micropumps 24 to be driven.

  Each of the plurality of micropumps 24 employs a micropump 100 shown in FIG. This micropump 100 is proposed in Patent Document WO2008 / 069266, and includes a primary blower chamber 101 and a secondary blower chamber 102 formed outside the primary blower chamber 101.

  The primary blower chamber 101 includes a piezoelectric element 103 serving as a vibration source, a diaphragm 104 to which the piezoelectric element 103 is fixed, and a vibration frame 105 that forms a space together with the diaphragm 104. The vibration frame 105 has an opening 106 that moves fluid inside and outside the primary blower chamber 101. The secondary blower chamber 102 has a suction port 107 on the diaphragm 104 side and a discharge port 108 so as to face the opening 106.

  In the micropump 100 described above, when the diaphragm 104 resonates by the piezoelectric element 103, the fluid moves between the primary blower chamber 101 and the secondary blower chamber 102, and the vibration frame 105 resonates due to the fluid resistance caused by the fluid. Due to the resonance between the diaphragm 104 and the vibration frame 105, the fluid is sucked from the suction port 107 and discharged from the discharge port 108.

  The micropump 100 is suitable for blower applications that transport gas, and can be transported without using a check valve. The micropump 100 has a box shape with an outer diameter of about 20 mm × 20 mm × 2 mm and is extremely small. However, when the input sine wave is set to 26 kHz at 15 Vpp (Volt peak to peak), the maximum is about 1 L / min (static pressure). Air at 0 Pa) and a maximum static pressure of about 2 kPa (flow rate 0 L / min) can be obtained.

  On the other hand, since the micropump 100 conveys fluid by the vibration of the diaphragm 104 by the piezoelectric element 103, the volume of the fluid that can be conveyed is naturally limited, and this static pressure / flow rate characteristic is also shown in FIG. A straight line. That is, for example, when a static pressure of about 1 kPa is obtained, the flow rate is 0.5 L / min.

  Note that, when the Vpp of the input sine wave is changed to 10 or 20, the amplitude of the piezoelectric element 103 changes, so that the flow rate and pressure can be changed. That is, when Vpp of the input sine wave is changed smoothly, the flow rate and pressure can be changed smoothly. Alternatively, when the frequency of the input sine wave is changed, the flow rate and pressure can be changed. That is, when the frequency of the input sine wave is changed smoothly, the flow rate and pressure can be changed smoothly. However, the flow rate and pressure have upper limits depending on the ability of the piezoelectric element 103, the strength of the member, and the durability. Usually used at rated Vpp and frequency.

  In this example, a monomorph (unimorph) structure in which one piezoelectric element 103 is attached to the diaphragm 104 is introduced. Of course, a bimorph structure in which two piezoelectric elements are attached to increase the vibration amount can also be adopted. . There are various other structures of the micropump 100 such as a structure suitable for liquid transport. Therefore, in the present invention, an optimum structure may be adopted according to the purpose. That is, the micropump 100 described here can convey gas without using a check valve, but instead of the micropump 100, a micropump having check valves at the suction port and the discharge port may be applied. good.

  As shown in FIG. 3, the control unit 14 includes, as hardware configurations, a CPU 28, a first storage medium 29, a second storage medium 30, a third storage medium 31, an input device 32, and a display device 33. The input / output interface 34 and the bus 35 are provided.

  The CPU 28 is a so-called central processing unit, and implements various functions of the control unit 14 by executing various programs. The first storage medium 29 is a so-called RAM (Random Access Memory) and is used as a work area for the CPU 28. The second storage medium 30 is a so-called ROM (Read Only Memory), and stores a basic OS executed by the CPU 28. The third storage medium 31 is composed of a hard disk device incorporating a magnetic disk, a disk device containing a CD, DVD, or BD, a non-volatile semiconductor flash memory device, and the like, and stores various programs executed by the CPU 28. Is done.

  The input device 32 is an input key, a keyboard, or a mouse, and inputs various information. The display device 33 is a display and displays various operation states. The input / output interface 34 inputs and outputs a power source (sine wave waveform) for operating the micropump 24 and a control signal. Further, the input / output interface 34 acquires data such as a program from an external personal computer. The bus 35 is a wiring that performs communication by integrally connecting the CPU 28, the first storage medium 29, the second storage medium 30, the third storage medium 31, the input device 32, the display device 33, the input / output interface 34, and the like. .

  FIG. 4 shows a functional configuration obtained by the CPU 28 executing the control program stored in the control unit 14. The control unit 14 includes a pump control unit 39 and a valve control unit 40 as functional configurations. The pump control unit 39 controls the Vpp and frequency of the input sine wave to the micropump 24 so as to approach the target desired flow rate value. The valve control unit 40 controls the merging valve 23 so that the ratio of oxygen and air approaches a target desired value.

  Next, a control example of the gas mixing device 10 will be described. The control unit 14 controls the merging valve 23 to adjust the ratio of the flow rate of oxygen and air. Specifically, when the flow rate of oxygen is increased, as shown in FIG. 2B, the oxygen path width Wo is made larger than the air path width Wa. On the other hand, when the flow rate of oxygen is reduced, as shown in FIG. 2C, the oxygen path width Wo is made smaller than the air path width Wa.

  Further, when increasing or decreasing the flow rate of the mixed gas generated by the gas mixing device 10, the control unit 14 performs control so as to change the number of micro pumps 24 to be driven.

  As described above, according to the gas mixing apparatus 10, the mixing ratio of oxygen and air can be changed with a short response time and high accuracy.

  FIG. 5 illustrates the configuration of the gas mixing system 50 of the second embodiment. Since the first embodiment and the second embodiment have many parts that are the same or similar, explanations thereof will be omitted, and here, differences from the first embodiment will be mainly described.

  The gas mixing system 50 comprehensively controls the gas mixing device 10, an oxygen supply unit 11 that supplies oxygen to the gas mixing device 10, an air supply unit 12 that supplies air to the gas mixing device 10, and the entire apparatus. A control unit 14.

  However, the gas mixing system 50 may include a plurality of control units that individually control the gas mixing device 10, the oxygen supply unit 11, and the air supply unit 12 in place of the control unit 14. In this case, the plurality of control units cooperate with each other to integrally control the entire system.

  The oxygen supply unit 11 is used together with the oxygen cylinder 15 and supplies oxygen that is compressed and confined in the oxygen cylinder 15 to the gas mixing unit 13. Specifically, the oxygen supply unit 11 is arranged in the middle of the flow rate adjusting valve 16 that adjusts the flow rate of oxygen released from the oxygen cylinder 15 and the flow from the flow rate adjusting valve 16 to the gas mixing unit 13, and oxygen is supplied. A gas chamber 17 having an atmosphere port 17a introduced and opened to the atmosphere, and a flow rate at the atmosphere port 17a, that is, a flow rate released from the gas chamber 17 to the atmosphere is detected, and the detected flow rate is detected. Is provided as a sensing signal.

  The flow rate adjustment valve 16 is controlled based on a sensing signal of the flow rate sensor 18 so that the inside of the gas chamber 17 has a pressure of about atmospheric pressure. The type of the flow rate adjusting valve 16 is not particularly limited, and an electric valve, an electromagnetic valve having a high response speed, or the like can be adopted.

  The gas chamber 17 is a space having a predetermined spread, and prevents oxygen from suddenly changing in the path from the flow regulating valve 16 to the gas mixing unit 13 when oxygen is released from the oxygen cylinder 15. Functions as a buffer space. In the present embodiment, the gas chamber 17 is disposed in the middle of the path from the flow rate adjustment valve 16 to the gas mixing unit 13, but may be disposed at a location branched from the path.

  The pressure in the gas chamber 17 is increased by introducing oxygen from the oxygen cylinder 15. On the other hand, the pressure in the gas chamber 17 is reduced by releasing oxygen in the gas chamber 17 from the atmosphere port 17 a to the atmosphere or releasing it to the gas mixing unit 13. That is, the pressure in the gas chamber 17 includes the flow rate of oxygen introduced from the oxygen cylinder 15, the flow rate of oxygen released from the atmosphere port 17 a to the atmosphere, and the flow rate of oxygen released to the gas mixing unit 13. Increase or decrease by percentage.

  In the present embodiment, the flow rate adjustment valve 16 is controlled to adjust the flow rate of oxygen introduced from the oxygen cylinder 15 and keep the pressure in the gas chamber 17 constant at about atmospheric pressure. Note that the flow rate of oxygen released from the atmosphere port 17a to the atmosphere is affected by the pressure in the gas chamber 17, and increases as the pressure in the gas chamber 17 increases. That is, in this embodiment, the flow rate of oxygen released from the atmosphere port 17a to the atmosphere is kept constant so that the pressure in the gas chamber 17 becomes constant at about atmospheric pressure.

  The flow rate of oxygen introduced from the oxygen cylinder 15 is adjusted by the flow rate adjustment valve 16. The flow rate of oxygen released from the atmosphere port 17a to the atmosphere is affected by the pressure in the gas chamber 17 and cannot be directly adjusted, but decreases when the pressure in the gas chamber 17 decreases. The flow rate of oxygen released to the gas mixing unit 13 is affected by the amount of oxygen used when the mixed gas is generated in the gas mixing unit 13 and cannot be directly adjusted. By controlling the amount of oxygen used when generating the mixed gas, the flow rate of oxygen released to the gas mixing unit 13 can be indirectly adjusted.

  The type of the flow sensor 18 is not particularly limited, and various types such as an electric type (electromagnetic type), a mechanical type (impeller type, float type, Kalman type, Coriolis type), ultrasonic type, thermal type, etc. The type can be adopted.

  The air supply unit 12 supplies air in the atmosphere to the gas mixing unit 13. Specifically, the air supply unit 12 includes a pump 19 that sends out air in the atmosphere, and a check valve 20 disposed in the middle of the path from the pump 19 to the gas mixing unit 13.

  The type of the pump 19 is not particularly limited, and a blower that sends a gas by rotating a fan, a cylinder pump that sends a gas by reciprocating a piston, and the like can be adopted. The check valve 20 prevents a back flow from the gas mixing unit 13 to the pump 19.

  In the present embodiment, the size of the atmosphere port 17a is constant, but a throttle valve (not shown) that makes the size of the atmosphere port 17a wider or narrower may be provided. The throttle valve is controlled together with the flow rate adjusting valve 16 based on a sensing signal of the flow rate sensor 18 and the like. Thereby, for example, the flow rate of oxygen released to the atmosphere increases by widening the atmosphere port 17a, so that even if the flow rate of oxygen released from the oxygen cylinder 15 increases, An increase in pressure is prevented. Moreover, since the flow rate of oxygen released into the atmosphere is reduced by narrowing the atmosphere port 17a, even if the flow rate of oxygen released from the oxygen cylinder 15 is reduced, it is released into the gas mixing unit 13. It is prevented that the flow rate of oxygen decreases.

  The gas mixing unit 13 has the same configuration as the structural portion of the gas mixing device 10 of the first embodiment. That is, the gas mixing unit 13 includes an oxygen path branching portion 21 that branches the path from the oxygen supply unit 11 into a plurality (in this embodiment, five) and a plurality of paths (from 5 in the present embodiment) to the air supply unit 12. A plurality of (five in the present embodiment) merging valves 23, a plurality (five in the present embodiment) micropumps 24, and a merging portion 25. (See FIG. 1A).

  The third storage medium 31 (see FIG. 3) in the control unit 14 further stores sensing data based on the sensing signal of the flow sensor 18. The input / output interface 34 (see FIG. 3) further inputs and outputs the sensing signal of the flow sensor 18 and outputs the sensing signal to an external personal computer.

  As shown in FIG. 5, the control unit 14 further includes a sensing unit 38 as a functional configuration. The sensing unit 38 always acquires the sensing signal of the flow sensor 18 and transmits it to the valve control unit 40. The pump control unit 39 further controls the pump 19 to approach the target desired flow rate value. The valve control unit 40 further refers to the sensing signal of the sensing unit 38 and controls the control signal to the flow rate adjusting valve 16 so as to approach the desired flow rate value as a target.

  Next, a control example of the oxygen supply unit 11 will be described.

  The control unit 14 stores in advance the flow rate at the atmosphere port 17a when the pressure in the gas chamber 17 is about atmospheric pressure. The control unit 14 uses this data as a reference, based on the sensing signal of the flow sensor 18, whether or not the flow rate at the atmosphere port 17a is higher than when the pressure in the gas chamber 17 is about atmospheric pressure, that is, the reference Determine whether there are more. If it is determined that there is more than the reference, the control unit 14 controls the flow rate adjustment valve 16 to decrease the flow rate of oxygen released from the oxygen cylinder 15. By always performing this control, the atmospheric pressure in the gas chamber 17 can be maintained at a pressure of about atmospheric pressure.

  Next, a control example of the gas mixing unit 13 will be described.

  As described above, in order to keep the pressure in the gas chamber 17 constant at about atmospheric pressure, the control unit 14 controls the flow rate adjustment valve 16 to increase or decrease the flow rate of oxygen released from the oxygen cylinder 15. The ratio of the flow rate of oxygen and air is adjusted by controlling the merging valve 23 corresponding to the control of the flow rate adjusting valve 16. Specifically, when the flow rate of oxygen released from the oxygen cylinder 15 is increased, the oxygen path width Wo is made smaller than the air path width Wa, as shown in FIG. On the other hand, when the flow rate of oxygen released from the oxygen cylinder 15 is decreased, the oxygen path width Wo is made larger than the air path width Wa, as shown in FIG.

  As described above, according to the gas mixing system 50, the inside of the airway can be set to a pressure of about atmospheric pressure while changing the desired flow rate of oxygen.

  In addition, the gas mixing apparatus of this invention is not limited to above-described embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. In addition, the configuration requirements of the above-described embodiment may be applied to other embodiments to the extent possible.

  That is, in each said embodiment, although the gas mixing apparatus 10 is an apparatus which mixes two types of gas, you may make it mix three or more types of gas.

  Alternatively, in each of the above embodiments, each of the merging valves 23 is a valve that adjusts the ratio of the flow rate of oxygen and air, but is a valve that switches the type of gas to be passed, that is, allows oxygen to pass or passes air. A valve for switching between them may be used. In this case, the ratio of the flow rate of oxygen and air as a total is adjusted by changing the number of valves through which oxygen passes and the number of valves through which air passes.

  Or although the said 2nd Embodiment demonstrated as an example the case where the inside of an airway can be set to the pressure about atmospheric pressure, it is not limited to this, You may enable it to set the inside of an airway to a desired pressure. In this case, the control unit 14 may store in advance the flow rate at the atmosphere port 17a when the atmospheric pressure in the gas chamber 17 becomes a desired pressure. And the control unit 14 should just be made to control on the basis of the data.

  Alternatively, in the second embodiment, the oxygen cylinder 15 is used as the first gas supply source. However, the supply source only needs to be able to send out the first gas, and may use a pump or the like.

10 Gas Mixing Device 11 Oxygen Supply Unit (Gas Supply Unit)
14 Control unit (control unit)
15 Oxygen cylinder (source)
16 Flow Control Valve 17 Gas Chamber 17a Atmosphere Port 18 Flow Sensor 23 Junction Valve 24,100 Micropump 25 Junction 50 Gas Mixing System

Claims (4)

A plurality of merging valves that are arranged in parallel with each other and each receive supply of a plurality of types of gas and allow the gases to pass therethrough;
A plurality of micropumps arranged one by one downstream of each of the plurality of merging valves, and sending out the gas that has passed through the merging valves;
A merging portion for merging the gas sent from each of the plurality of micropumps downstream of the plurality of micropumps,
Gas mixing device. Each of the plurality of merging valves adjusts a flow rate ratio of the plurality of types of gases,
The gas mixing device according to claim 1. Each of the plurality of merging valves is characterized by switching the type of gas to be passed.
The gas mixing device according to claim 1. A gas mixing device according to any one of claims 1 to 3,
A gas supply unit that supplies a first gas to each of the plurality of merging valves,
The gas supply unit includes:
A flow rate adjusting valve for adjusting a flow rate of the first gas discharged from the source of the first gas;
In the middle of the path from the flow rate adjusting valve to the plurality of merging valves, or at a place branched from the path, the first gas is introduced, and an air outlet opening toward the atmosphere is provided. A gas chamber comprising:
A flow rate sensor that detects the flow rate at the atmosphere port and outputs the detected flow rate as a signal;
A controller that receives the signal output from the flow sensor and controls the flow control valve based on the signal;
Gas mixing system.

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