JP2013194533A - Fluid circulation device and medical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique with which a fluid can be circulated while ensuring a flow rate.SOLUTION: A fluid circulation device includes: a pump chamber which performs a pumping action; an inflow channel; a fluid resistance element which suppresses or blocks a fluid flowing from the pump chamber to the inflow channel; a discharge port; a circulation channel that is a tubular channel in which the fluid is circulated from the discharge port to the inflow channel; and a fluid storage section which is provided on the circulation channel, stores the fluid while the pumping action is stopped, and supplies the stored fluid as a part of the circulating fluid while the pumping action is performed. When a flow rate of the fluid circulating in the circulation channel during the pumping action is defined as Q, channel resistance per unit length of the circulation channel from the fluid storage section to an inflow channel side end portion is defined as R and a suction pressure that is a pressure for the pump chamber to suck the fluid is defined as Pv (Pv>0), the fluid storage section is provided at a position of a length h satisfying a predetermined relational expression from the inflow channel side end portion on the circulation channel.

Description

  The present invention relates to a fluid circulation device and a medical device using the fluid circulation device.

  Conventionally, as a technique for adjusting the temperature of an object, a technique using a fluid circulation device is known (for example, Patent Document 1). In this technique, an object whose temperature is to be adjusted (hereinafter also referred to as a temperature adjustment target) is brought into contact with a circulation channel through which a fluid circulates, and the temperature of the temperature adjustment target is set by the heat of the circulating fluid. adjust. However, in the conventional fluid circulation device, the pressure at the time of circulation of the fluid is not taken into consideration, and thus there is a problem that the fluid may not be circulated while securing a preset flow rate.

JP-A-8-242463

  The present invention has been made to solve the above-described conventional problems, and an object thereof is to ensure a predetermined flow rate and circulate a fluid.

  In order to solve at least a part of the problems described above, the present invention can take the following forms or application examples.

この流体循環装置によると、ポンプ室が循環流路を介して流体収容部から流体を吸入するために必要な圧力に比べて、ポンプ室の吸入圧力Ｐｖが大きくなる位置に流体収容部を備えるので、ポンプ室は流体収容部から流量Ｑで流体を吸入することができる。結果として、流量Ｑを確保して循環流路に流体を循環させることができる。 [Application Example 1]
A fluid circulation device that performs a pumping operation for sucking and discharging fluid; an inflow passage that is a passage through which fluid flows into the pump chamber; and the heading from the pump chamber toward the inflow passage. A fluid resistance element that suppresses or inhibits the flow of fluid, a fluid discharge port from the pump chamber, a circulation channel that is a tubular channel through which the fluid circulates from the discharge port to the inflow channel, A fluid storage section that is provided on the circulation flow path and that stores the fluid when the pump operation is stopped and supplies the stored fluid as a part of the circulating fluid when the pump is operating. , Where Q is the flow rate of the fluid circulating through the circulation channel during the pump operation, and per unit length of the circulation channel from the fluid storage unit to the inflow channel side end during the pump operation. When the path resistance is R and the suction pressure, which is the pressure at which the pump chamber sucks the fluid, is Pv (Pv> 0), the fluid storage portion is an end on the inflow channel side on the circulation channel. To a fluid circulation device provided at a position of a length h that satisfies the relationship of formula (3).

According to this fluid circulation device, since the pump chamber includes the fluid storage portion at a position where the suction pressure Pv of the pump chamber becomes larger than the pressure required to suck the fluid from the fluid storage portion via the circulation flow path. The pump chamber can suck fluid from the fluid storage portion at a flow rate Q. As a result, it is possible to ensure the flow rate Q and circulate the fluid through the circulation channel.

この流体循環装置によると、循環流路の流路断面形状が所定の大きさの円形である場合に、流量Ｑを確保して流体を循環させることができる。 [Application Example 2]
In the fluid circulation device according to Application Example 1, in the case where the viscosity of the fluid is μ and the diameter of the circulation channel is d, the fluid storage portion is an end on the inflow channel side on the circulation channel. A fluid circulation device provided at a position of a length h that satisfies the relationship of formula (4) from the section.

According to this fluid circulation device, when the cross-sectional shape of the circulation channel is a circular shape having a predetermined size, the fluid can be circulated with the flow rate Q secured.

[Application Example 3]
The fluid circulation device according to Application Example 1 or Application Example 2, wherein the circulation channel includes a tubular suction channel formed integrally with the inflow channel, the suction channel, and the discharge conduit. And a tubular fluid flow path that connects the fluid flow paths, and the fluid storage portion is provided by branching from the suction flow path.
According to this fluid circulation device, the fluid storage portion is provided by branching from the tubular suction pipe formed integrally with the suction flow path, so that a structure having high strength can be obtained.

[Application Example 4]
The fluid circulation device according to any one of Application Example 1 to Application Example 3, wherein the fluid storage unit includes a fluid storage chamber that stores the fluid used for the supply, and is stored in the interior. A fluid circulation device that is deformable according to the amount of the fluid.
According to this fluid circulation device, since the fluid storage chamber that can be deformed according to the amount of fluid stored in the interior is used as the fluid storage section, even if the amount of fluid stored in the interior changes, The pressure can be kept constant.

[Application Example 5]
The fluid circulation device according to application example 4, wherein the fluid storage chamber is a pack formed by sealing a film in a bag shape.
According to this fluid circulation device, since the pack is used as the fluid storage chamber, a simple configuration can be achieved.

[Application Example 6]
The fluid circulation device according to any one of Application Example 1 to Application Example 5, wherein the fluid storage unit is a branch channel branched from the circulation channel.
According to this fluid circulation device, since the branch flow path is used as the fluid storage portion, the fluid storage portion can be made a simple structure.

[Application Example 7]
The fluid circulation device according to Application Example 6, wherein the accommodated fluid is sealed in the branch flow path, and the pressure difference between the pressure of the fluid in the branch flow path and atmospheric pressure A fluid circulation device in which a sealing material that moves in accordance with the pressure is arranged.
According to this fluid circulation device, since the sealing material is disposed in the branch channel, it is possible to prevent the liquid from flowing out from the branch channel.

[Application Example 8]
The fluid circulation device according to Application Example 7, wherein the fluid is a first liquid, and the first liquid and the sealing material are disposed between the first liquid and the sealing material in the branch channel. A fluid circulation device in which a second liquid that is phase-separable from one liquid is sealed, and the heat of vaporization of the second liquid is greater than the heat of vaporization of the first liquid.
According to this fluid circulation device, vaporization of the first liquid from the branch channel can be suppressed.

[Application Example 9]
A medical device using the fluid circulation device according to any one of Application Example 1 to Application Example 8.
According to this configuration, since the fluid circulates stably in the fluid circulation device, the reliability of the medical device can be improved.

  Note that the present invention can be realized in various modes. For example, the present invention can be realized in the form of a fluid circulation method and apparatus, a fluid circulation system, a temperature adjustment device, and the like.

It is explanatory drawing which shows schematic structure of a fluid injection system. It is a schematic diagram which shows roughly the structure of the cross section of a fluid circulation apparatus. It is explanatory drawing which shows the flow of the liquid in the inside of a circulation pump. It is explanatory drawing which shows the structure of a film pack. It is explanatory drawing explaining the internal pressure of a liquid flow path. It is explanatory drawing explaining the structure of a branch flow path. It is explanatory drawing explaining the fluid circulation apparatus in the modification 1. It is explanatory drawing which showed the fluid resistance element which can be employ | adopted.

A. First embodiment:
(A1) System configuration:
Embodiments of the present invention will be described based on examples. FIG. 1 is an explanatory diagram showing a schematic configuration of a fluid ejection system 10 as an embodiment of the present invention. The fluid ejection system 10 includes a fluid ejection device 20 and a fluid circulation device 100 that cools the fluid ejection device 20. The fluid ejecting apparatus 20 is a water jet knife that ejects a jet water flow onto a living tissue such as skin and peels and incises the living tissue by the impact energy. In particular, the fluid ejection device 20 of the present embodiment is a water jet pulse knife that intermittently ejects a jet water flow.

  The fluid ejection device 20 includes a pulsation generating unit 30 that ejects a jet water flow, a fluid container 40 that stores water, a supply pump 42 that sucks up water that is stored in the fluid container 40 and supplies the water to the pulsation generating unit 30. A connection tube 44 that connects the fluid container 40 and the supply pump 42 and a connection tube 46 that connects the supply pump 42 and the pulsation generator 30 are provided.

  The pulsation generating unit 30 communicates with the fluid chamber 32, a fluid chamber 32 that temporarily stores water supplied from the connection tube 46, a piezoelectric actuator 34 that pulsates the water stored in the fluid chamber 32, and the fluid chamber 32. A fluid jet pipe 36 through which water pulsated by the piezoelectric actuator 34 passes, a lower case 38 that houses the piezoelectric actuator 34 therein, and a fluid chamber 32, and an upper case 39 connected to the lower case 38. And.

  The piezoelectric actuator 34 is a laminated piezoelectric element, and changes the volume of the fluid chamber 32 by deforming the diaphragm using the piezoelectric effect of the piezoelectric element (piezo element). When the volume of the fluid chamber 32 is reduced, the water stored in the fluid chamber 32 is jetted to the outside through the fluid jet pipe 36 as a jet water flow.

  The fluid circulation device 100 is a device that cools the piezoelectric actuator 34 of the fluid ejection device 20, and includes a circulation pump 110 and a liquid flow channel 190 that is a circulation flow channel having both ends connected to the circulation pump 110. The liquid channel 190 is a tube having pressure resistance and flexibility. The tube having pressure resistance and flexibility is, for example, a medical tube or a general industrial tube made of a thermoplastic resin such as PTFE or other fluororesin, polyimide resin or PVC resin, or silicone rubber. Although it is possible, it is not particularly limited to this. It is wound around the piezoelectric actuator 34. For this reason, the heat generated in the piezoelectric actuator 34 is transmitted to the fluid circulating in the liquid flow path 190 (circulating fluid), and the piezoelectric actuator 34 is cooled. The circulating fluid whose temperature has risen is cooled by air cooling while circulating in the liquid channel 190. In addition, the circulating fluid may be cooled separately using a radiator. In this embodiment, the circulating fluid is a liquid in consideration of heat exchange efficiency. In the fluid circulation device 100, water is used as the liquid.

  FIG. 2 is a schematic diagram schematically showing a cross-sectional configuration of the fluid circulation device 100. In the present embodiment, in the fluid circulation device 100, a closed circulation path is configured by the circulation pump 110 and the liquid flow path 190. The closed circulation path means a circulation path having no part where the circulating fluid is in contact with the outside (atmosphere). By adopting a closed circulation channel, it is possible to prevent bubbles and other foreign matters from entering the circulating fluid. Further, by preventing the circulating fluid itself from volatilizing and reducing its amount, the flow rate of the circulating fluid can be secured stably, contributing to maintaining stable circulation efficiency.

  The circulation pump 110 includes a laminated piezoelectric element 114, a piezoelectric element case 112 that accommodates the piezoelectric element 114 therein, and a flow path case 140 in which a flow path is formed. The bottom of the piezoelectric element 114 is fixed to the piezoelectric element case 112. A circular reinforcing plate 116 is attached to the upper end of the piezoelectric element 114, and a circular diaphragm 118 formed of a thin metal plate or the like is bonded to the upper surface of the reinforcing plate 116. The reinforcing plate 116 reinforces the strength of the diaphragm 118. The thickness of the reinforcing plate 116 is set so that the lower surface of the diaphragm 118 is in contact with the upper end surface of the piezoelectric element case 112.

  A recess 140C is formed on the lower surface side of the flow path case 140 (side facing the piezoelectric element case 112), and an annular member 120 is fitted in the recess 140C. The inner diameter of the annular member 120 is smaller than the outer diameter of the diaphragm 118. When the piezoelectric element case 112 and the flow path case 140 face each other and are fixed by screws or the like, the diaphragm 118 is sandwiched between the annular member 120 and the piezoelectric element case 112, and between the flow path case 140 and the diaphragm 118. The airtightness is secured by the annular member 120. As a result, a pump chamber 130 that is a space surrounded by the recess 140 </ b> C of the case 140, the inner peripheral surface of the annular member 120, and the diaphragm 118 is formed. The volume of the pump chamber 130 changes as the piezoelectric element 114 expands or contracts and the diaphragm 118 deforms.

  The flow path case 140 further includes a liquid chamber 146 that guides the liquid to the pump chamber 130 and a pump discharge flow path 142 that is connected to one end of the liquid flow path 190 and guides the liquid in the pump chamber 130 to the liquid flow path 190. And a pump suction flow path 144 that is connected to the other end of the liquid flow path 190 and guides the liquid supplied from the liquid flow path 190 to the liquid chamber 146.

  The liquid chamber 146 communicates with the pump chamber 130 and is formed so that the diameter decreases toward the pump chamber 130 (so that the cross-sectional area decreases). A check valve 148 is provided at the boundary between the liquid chamber 146 and the pump chamber 130. The check valve 148 allows the liquid to flow from the liquid chamber 146 to the pump chamber 130 and prevents the liquid from flowing back from the pump chamber 130 to the liquid chamber 146.

  On the liquid channel 190, the film pack 160 is airtightly connected via a connection member 162 at a position branched from the liquid channel 190. The film pack 160 is formed of a flexible film having gas barrier properties and heat resistance in order to prevent air bubbles from being mixed into the circulating fluid. The film pack 160 is detachable from the connecting member 162. The installation position of the film pack 160 on the liquid flow path 190 will be described in detail later.

  The fluid circulation device 100 configured as described above circulates the liquid in the liquid flow path 190 by driving the piezoelectric element 114 of the circulation pump 110. Next, details of the operation of the circulation pump 110 will be described.

(A2) Operation of circulation pump 110:
FIG. 3 is an explanatory diagram showing the flow of the liquid inside the circulation pump 110. FIG. 3A is an explanatory diagram illustrating a state where the circulation pump 110 is not operating (a state before a driving voltage is applied to the piezoelectric element 114). Hereinafter, a state where the circulation pump 110 is operating is also referred to as an operating state, and a state where the circulation pump 110 is not operating is also referred to as a stopped state. In the stop state, the pressure inside the pump chamber 130 and the liquid flow path 190 is atmospheric pressure. In the stopped state, the pump chamber 130 is filled with liquid. In the stopped state, the film pack 160 also contains a predetermined amount of liquid in advance. The liquid stored in the film pack 160 in the stopped state (hereinafter also referred to as pressure adjusting liquid BF) is used to adjust the inside of the liquid flow path 190 to an appropriate pressure in the operating state. Details of the pressure adjusting liquid BF will be described later.

  FIG. 3B is an explanatory diagram showing a state in which a driving voltage is applied to the piezoelectric element 114. When a drive voltage is applied to the piezoelectric element 114 in a state where the pump chamber 130 is filled with liquid, the piezoelectric element 114 expands due to the applied drive voltage, and the diaphragm 118 is moved through the reinforcing plate 116 to the pump chamber 130. Push up in the direction of. When the pump chamber 130 is pushed by the diaphragm 118, the volume of the pump chamber 130 decreases and the liquid in the pump chamber 130 is pressurized. At this time, the check valve 148 is closed and the back flow of the liquid from the pump chamber 130 to the liquid chamber 146 is prevented, so that the liquid corresponding to the reduced volume of the pump chamber 130 passes through the pump discharge flow path 142. Thus, it is pumped toward the liquid channel 190.

  When the liquid is sent into the liquid flow path 190 in this way, the liquid in the liquid flow path 190 is successively pushed downstream. Further, as described above, in the fluid circulation device 100 of the present embodiment, the liquid flow path 190 and the circulation pump 110 constitute a closed system, and the liquid pushed into the liquid flow path 190 is the liquid flow path 190. And flow into the connected film pack 160. Here, the film pack 160 is formed of a flexible film, and is attached in a state in which the liquid pack 160 is not completely filled with the liquid but is still inflated. Therefore, even if the liquid flows into the film pack 160, the pressure in the film pack 160 and the liquid flow path 190 communicating with the film pack 160 is suppressed by the film pack 160 expanding.

  FIG. 3C is an explanatory diagram showing a state in which the driving voltage applied to the piezoelectric element 114 has decreased. When the drive voltage decreases, the piezoelectric element 114 contracts and returns to its original length. Then, the volume of the pump chamber 130 increases (restores to the original volume). At this time, since the pressure in the pump chamber 130 becomes negative, the check valve 148 is opened, and the liquid is sucked into the pump chamber 130 from the film pack 160 via the liquid chamber 146 and the pump suction flow path 144. . The negative pressure refers to a pressure below atmospheric pressure.

  The negative pressure in the pump chamber 130 also acts on the pump discharge channel 142. However, the flow resistance of the pump discharge flow path 142 is set larger than the flow resistance from the film pack 160 to the check valve 148. Therefore, it is easier for the liquid to flow from the liquid chamber 146 to the pump chamber 130 than the pump discharge flow path 142. Further, since the liquid chamber 146 communicates with the film pack 160 through the liquid flow path 190, the liquid in the film pack 160 flows into the pump chamber 130 without stagnation.

  After the pump chamber 130 whose volume has been recovered in this way is filled with the liquid flowing in from the liquid chamber 146, when the piezoelectric element 114 expands again due to an increase in driving voltage, as shown in FIG. The liquid pressurized in 130 is pumped toward the pump discharge channel 142 and the liquid channel 190. When the circulation pump 110 repeats the above operation, the fluid circulation device 100 circulates the liquid in the liquid flow path 190.

(A3) Structure of film pack:
FIG. 4 is an explanatory diagram showing the configuration of the film pack 160. FIG. 4A shows an exploded perspective view of the film pack 160. The film pack 160 includes a pair of flexible films 164 having gas barrier properties and heat resistance, a connecting member 162 having a communication hole 162a and detachably connecting the film pack 160 to the liquid chamber 146, and an openable opening. It is composed of an open mouth member 166 provided with a mouth. The pair of films 164 are formed in a substantially rectangular shape. The film pack 160 is formed by sandwiching the connection member 162 on one end side in the longitudinal direction of the pair of films 164, sandwiching the open port member 166 on the other end side, and airtightly bonding the periphery by thermocompression bonding or the like.

  FIG. 4B shows a film pack 160 formed by bonding a pair of films 164 together. In FIG. 4B, the seal portion bonded by thermocompression bonding or the like is shown with hatching. As shown in FIG. 4B, the film pack 160 is in a state in which the pair of films 164 are in contact with each other in a state where no liquid is accommodated therein.

  On the other hand, when the liquid flows into the film pack 160 through the communication hole 162a of the connection member 162, the film pack 160 swells as the pair of films 164 separate from each other as shown in FIG. The liquid can be accommodated. Further, when the liquid in the film pack 160 flows out through the communication hole 162a of the connecting member 162, the pair of films 164 approach each other and the film pack 160 is deflated (the volume is reduced). In this way, the film pack 160 can be deformed according to the amount of liquid stored inside.

  FIG. 4D illustrates the structure of the film 164 used for the film pack 160. The illustrated film 164 has a multilayer structure, and is bonded to both sides of an aluminum foil (AL) with polypropylene (PP) having excellent liquid resistance, and from above, polyethylene having excellent impact resistance on both sides. A structure in which terephthalate (PET) is bonded is adopted. Each layer is bonded by an adhesive. By providing the middle layer of the aluminum foil, the strength of the film can be enhanced and the gas barrier property can be enhanced. The film pack 160 having such a configuration has excellent heat resistance, can be handled at a high temperature (for example, 150 ° C.), has flexibility, and can be easily deformed. Further, the film pack 160 can be easily formed by thermocompression bonding in addition to realizing weight reduction.

  The structure of the film 164 used for the film pack 160 is not limited to the structure shown in FIG. 4 (D). For example, instead of aluminum foil as the middle layer, ethylene-vinyl alcohol copolymer resin (EVOH), Polyvinylidene chloride (PVDC) or the like may be used. Alternatively, the outer layer of polyamide (nylon) and the inner layer of polypropylene (PP) may be directly bonded with an adhesive to form a transparent film. By making the film pack 160 transparent, it becomes possible to visually recognize the inside of the film pack 160 (the amount of liquid and the flow of liquid).

(A4) Installation position of the film pack 160:
Next, the installation position of the film pack 160 in the liquid channel 190 will be described. In the fluid circulation device 100 in the present embodiment, the installation position of the film pack 160 is determined so that a predetermined flow rate Q (unit: [ml / min]) is secured and the liquid circulates in the liquid flow path 190. FIG. 5 is an explanatory diagram for explaining the internal pressure in the liquid flow path 190 when the liquid circulates while ensuring a predetermined flow rate Q in the liquid flow path 190.

  The upper part of FIG. 5 shows a model of the fluid circulation device 100 (internal pressure consideration model) for considering the internal pressure in the liquid flow path 190. As shown in the figure, in the internal pressure consideration model, the liquid flow path 190 is shown on a straight line and the film pack 160 is simply shown for easy consideration. In the internal pressure consideration model in the present embodiment, the liquid flow path 190 and the pump suction flow path 144 are regarded as a series of tubular flow paths (hereinafter also referred to as a circulation flow path 195) having a circular cross-sectional shape. Then, consider the internal pressure. The connection point between the pump discharge flow path 142 and the circulation flow path 195 is defined as a flow path start point S, and the boundary between the circulation flow path 195 and the liquid chamber 146 is defined as a flow path end point E. That is, the flow path end point E is a boundary point between the pump suction flow path 144 and the liquid chamber 146.

  In addition, the length (hereinafter also referred to as a separation distance) from the installation position of the film pack 160 to the channel end point E in the circulation channel 195 is h (unit: [m]). In FIG. 5, the flow path end point E and the liquid chamber 146 are shown as separated from each other, but in the actual fluid circulation device 100, the flow path end point E and the liquid chamber 146 are connected. The broken-line arrows shown in the figure indicate the direction in which the liquid flows. Further, the internal pressure of the circulation flow path 195 at the flow path start point S in the operation state of the circulation pump 110 is the pressure Pout, and the internal pressure value of the flow path end point E of the circulation flow path 195 in the operation state of the circulation pump 110 is the pressure Pin. To do.

  The circulation pump 110 pressurizes the liquid that has flowed into the pump chamber 130 from the pump suction flow path 144, and pumps the liquid from the pump discharge flow path 142 toward the circulation flow path 195 with a pressure Pin. Then, a pressure gradient is generated in the internal pressure of the circulation flow path 195 by the liquid pumping by the circulation pump 110, and the liquid flows through the circulation flow path 195 at a flow rate Q by the generated pressure gradient and flows into the film pack 160.

  Then, when the volume of the pump chamber 130 increases (see FIG. 3C), the liquid is sucked from the film pack 160 at a predetermined pressure through the pump suction flow path 144, thereby causing the film pack 160 and the flow path to flow. Even with the end point E, the liquid Q can be circulated with the flow rate Q secured. In this embodiment, since the circulation channel 195 has a tubular structure, the liquid flow in the circulation channel 195 is treated as a laminar flow. In this embodiment, the internal pressure of the liquid flow path 190 is considered by such an internal pressure consideration model.

  The lower part of FIG. 5 shows an internal pressure distribution model of the circulation channel 195 in the case where the liquid circulates in the circulation channel 195 at the flow rate Q. In the internal pressure distribution model, the horizontal axis is the position x from the flow path start point S in the circulation flow path 195, and the vertical axis is the internal pressure P (x) at the position x. The internal pressure P (x) is expressed as a relative pressure (atmospheric pressure is 0). The internal pressure of the liquid flowing out from the pump discharge channel 142 into the circulation channel 195 decreases with the channel resistance of the circulation channel 195 as the position x increases. That is, as described above, a pressure gradient is generated in the internal pressure of the liquid channel 190. In this embodiment, the pressure gradient in the circulation channel 195 employs a linear model.

  The internal pressure of the circulation channel 195 at the installation position of the film pack 160 is 0 (atmospheric pressure). This is because the liquid in the film pack 160 flows into or out of the circulation channel 195 according to the difference between the internal pressure of the circulation channel 195 near the installation position of the film pack 160 and the atmospheric pressure. . As can be seen from this, the film pack 160 can make the internal pressure of the circulation flow path 195 at the installation position thereof atmospheric pressure. Therefore, by controlling the installation position, when the circulation pump 110 secures the flow rate Q and circulates the liquid, it is possible to prevent the internal pressure of the circulation flow path 195 from falling below a predetermined pressure. it can. For example, if the film pack 160 is installed in the vicinity of the flow path end point E, the internal pressure in the vicinity of the flow path end point E can be controlled to be 0 (atmospheric pressure).

  Moreover, the film pack 160 contains the pressure adjustment liquid BF in advance in a stopped state. This is because, in the operation state of the circulation pump 110, the internal pressure of a part of the circulation flow path 195 becomes equal to or higher than the atmospheric pressure, and this part corresponds to expansion. That is, the total volume in which the circulation pump 110 and the circulation flow path 195 contain liquid (hereinafter also referred to as fluid storage total volume) is the total volume of the circulation fluid (hereinafter referred to as total circulation fluid volume) due to the expansion of the circulation flow path 195. In order to compensate for the difference, the pressure adjustment liquid BF is previously stored in the film pack 160 in the stopped state. In the operating state of the circulation pump 110, when the difference between the total volume of fluid accommodation and the total volume of the circulating fluid occurs and the internal pressure of the circulation flow path 195 moves in a direction that decreases below atmospheric pressure, the pressure of the film pack 160 is increased. The adjustment liquid BF is automatically supplied to the circulation flow path 195 according to the atmospheric pressure, and compensates for the difference between the total fluid storage volume and the total circulation fluid volume.

  As described above, when the film pack 160 is installed in the vicinity of the flow path end point E and the internal pressure of the circulation flow path 195 is adjusted to be equal to or higher than the atmospheric pressure by the pressure adjusting liquid BF, The internal pressure becomes equal to or higher than atmospheric pressure, and deformation of the circulation channel 195 in the inward direction due to the difference between the internal pressure and atmospheric pressure can be avoided. Therefore, the film pack 160 is preferably provided in the vicinity of the flow path end point E.

  On the other hand, as shown in the internal pressure distribution model of FIG. 5, when the separation distance h is increased, the circulation pump 110 is connected to the circulation channel 195 in order to suck liquid from the film pack 160 into the liquid chamber 146 at a flow rate Q. It is necessary to inhale liquid at a predetermined pressure or higher. This will be described in detail below.

  When the flow resistance per unit length of the circulation flow path 195 is flow resistance R (unit: kg / m ^ 5 · S), in order to generate the flow of the flow rate Q in the circulation flow path 195, a film It is necessary to apply a pressure gradient of “R · Q” to the internal pressure between the pack 160 and the flow path end point E. Considering that the internal pressure of the film pack 160 is “0”, when the internal pressure at the flow path end point E is set to the internal pressure Pin = −R · Q · h, the film pack 160 and the flow path end point E A pressure gradient having a magnitude of “R · Q” can be applied therebetween.

Here, the pressure at which the circulation pump 110 can apply the liquid to the flow path end point E during the suction is defined as the suction pressure Pv (Pv> 0), and is used as a reference value for the pressure at which the circulation pump 110 sucks the liquid. That is, when the circulation pump 110 sucks liquid from the circulation flow path 195 at the suction pressure Pv, the internal pressure Pin = −Pv at the flow path end point E is obtained at the relative atmospheric pressure (atmospheric pressure is 0). When defined in this way, the circulation pump 110 can generate the flow of the flow rate Q between the film pack 160 and the flow path end point E by satisfying the following formula (5). Q can inhale liquid.

Moreover, when Formula (5) is expressed as a restriction on the separation distance h, it can be expressed as the following Formula (6).

Expression (6) represents the upper limit value of the separation distance h. On the other hand, as the lower limit value of the separation distance h, the closer the film pack 160 is to the flow path end point E, the more the suction pressure Pv applied to the flow path end point E can be, the more the flow rate Q can be generated. The lower limit of h is h> 0. Therefore, when the separation distance h satisfies the following formula (7), the circulation pump 110 having the suction pressure Pv can suck the liquid from the film pack 160 at the flow rate Q.

Here, assuming that the channel diameter of the circulation channel 195 is d and the viscosity of the liquid circulating in the liquid channel 190 is μ (unit: Pa · s), the channel per unit length is calculated according to Hagen-Poiseuille's law. The resistance R can be expressed as the following formula (8).

Therefore, the following equation (9) is derived from the equations (7) and (8).

In this embodiment, the suction pressure Pv of the circulation pump 110 is 10 [kpa], the channel diameter d of the liquid channel 190 is 0.0005 [m], and the viscosity of the liquid (water) μ = 0.001 [Pa · s], flow rate Q = 5 [ml / min]. Therefore, by installing the film pack 160 at a position where the separation distance h [m] satisfies the following formula (10), the circulation pump 110 circulates the liquid while ensuring a flow rate Q = 5 [ml / min]. Can do.

  In the fluid circulation device 100 of the present embodiment, the film pack 160 is provided at a position where the separation distance h satisfies the expression (10) based on the above-described restriction of the separation distance h. As a result, the circulation pump 110 can circulate the liquid while ensuring the flow rate Q = 5 [ml / min] without deteriorating the pump characteristics. In particular, as the separation distance h is closer to 0, the internal pressure Pin becomes sufficiently smaller than the suction pressure Pv, so that the burden on the circulation pump 110 is reduced and the circulation pump 110 operates stably. Further, as can be seen from the equation (10), the separation distance h may be provided in the vicinity of the flow path end point E, so that the film pack 160 is provided in the pump suction flow path 144 as will be described in Modification 1 described later. It is good.

  As described above, since the fluid circulation device 100 includes the film pack 160, the internal pressure of the circulation channel 195 can be controlled. Further, since the fluid circulation device 100 is provided with the film pack 160 at the position of the circulation flow path 195 where the separation distance h satisfies the expression (10), the flow path necessary for sucking the liquid from the film pack 160 at the flow rate Q. Compared with the pressure drop amount “R · Q · h” at the end point E, the suction pressure Pv can be increased. Therefore, the circulation pump 110 can circulate the liquid through the circulation channel 195 at the flow rate Q. Further, by providing the film pack 160 on the liquid flow path 190, the film pack 160 can be easily detached from the fluid circulation device 100, and assembly and maintenance can be easily performed.

B. Second embodiment:
Next, a second embodiment of the present invention will be described. In the second embodiment, a fluid circulation device 200 is used instead of the fluid circulation device 100 as a fluid circulation device. Although the fluid circulation device 100 in the first embodiment stores the pressure adjusting liquid BF in the film pack 160, the fluid circulation device 200 in the second embodiment is provided in the liquid flow path 190 instead of the film pack 160. The pressure adjusting liquid BF is accommodated in the branch channel 210. Since the configuration other than the branch flow path 210 is the same as that of the first embodiment, the description of the configuration other than the branch flow path 210 is omitted. In addition, the same code | symbol is used about the same structure in 1st Example and 2nd Example.

  FIG. 6 is an explanatory diagram illustrating the configuration of the branch flow path 210 in the present embodiment. The branch flow path 210 is provided at a position of a separation distance h on the circulation flow path 195 that satisfies Expression (10). The branch flow path 210 is made of a material having a high gas barrier property and is less likely to volatilize the internal liquid. In the branch flow path 210, the liquid that circulates through the liquid flow path 190 by the operation of the circulation pump 110 is accommodated, including the pressure adjusting liquid BF. Hereinafter, the liquid circulating through the circulation pump 110 and the liquid flow path 190 is also referred to as a first liquid Lq1.

  The branch flow path 210 is installed so that the position of the liquid head of the first liquid Lq1 is higher than the circulation pump 110. A first liquid Lq1 having a volume Vb is accommodated in the branch flow path 210, and functions as the pressure adjusting liquid BF in the operation state of the circulation pump 110.

  As illustrated, the branch channel 210 includes a movable portion 216 therein. The branch flow path 210 has a vent hole 218 as an air flow path, and is configured such that the movable portion 216 is in contact with outside air. The movable part 216 includes the second liquid Lq2 and the high-viscosity gel fluid 214. The second liquid Lq2 is located in contact with the liquid head of the first liquid Lq1. When the position of the liquid head of the first liquid Lq1 moves, the movable portion 216 moves in the height direction of the branch flow path 210 while being in contact with the liquid head of the first liquid Lq1. The inner wall surface of the branch flow path 210 has a smooth surface so that the movable part 216 can move smoothly. In addition, the fluid circulation device 200 includes a sensor 230 that can measure the amount of movement of the movable part 216 in the vicinity of the branch flow path 210, and can measure the amount of movement of the movable part 216.

  The high-viscosity gel fluid 214 that is a constituent element of the movable portion 216 is sealed as a sealing material for preventing leakage of the first liquid Lq1 from the branch flow path 210 and preventing evaporation (a liquid ballpoint pen liquid stopper). The same principle). The high viscosity gel fluid 214 is based on polybutene having an average molecular weight of 630 and has viscoelasticity and transparency. As the high-viscosity gel fluid 214, polybutene, α-olefin, or the like having an average molecular weight of 300 to 3700 can be used.

  Further, it is desirable that the high-viscosity gel fluid 214 is substantially incompatible with the first liquid Lq1. When an oily medium is used for the first liquid Lq1, an aqueous high-viscosity gel using water as a medium can be used. When the aqueous high-viscosity gel fluid 214 is used and the gas permeability of the high-viscosity gel fluid 214 is high or it is easy to dry, an organic solvent is further added on the high-viscosity gel fluid 214. An oily layer as a solvent may be formed to prevent permeation and drying.

  The second liquid Lq2 is accommodated in the branch flow path 210 in order to prevent the high-viscosity gel fluid 214 from dissolving in the first liquid Lq1. The second liquid Lq2 is a liquid having a larger heat of vaporization than the first liquid Lq1, and is a liquid that can be phase-separated from the first liquid Lq1. Further, the density of the second liquid Lq2 is smaller than that of the first liquid Lq1. In this embodiment, liquid paraffin is used as the second liquid Lq2. In addition, calcium alginate can be used as the second liquid Lq2.

  In the fluid circulation device 200 having the above-described configuration, when the circulation pump 110 operates, a pressure gradient is generated in the internal pressure of the liquid flow path 190 as described in the first embodiment. Then, due to the volume change of the liquid flow path 190, the pressure in the vicinity of the flow path end point E of the liquid flow path 190 moves in a direction below atmospheric pressure. At that time, due to the pressure difference between the internal pressure in the vicinity of the flow path end point E and the atmospheric pressure applied to the branch flow path 210, the first liquid Lq1 (corresponding to the pressure adjusting liquid BF) in the branch flow path 210 enters the liquid flow path 190. Supplied. As a result, the internal pressure of the circulation flow path 195 at the installation position of the branch flow path 210 is maintained at 0 (atmospheric pressure), and the circulation pump 110 can operate with the internal pressure of the circulation flow path 195 in an appropriate state. it can.

  As described above, in the fluid circulation device 200, the branch flow path 210 is provided at the position of the separation distance h on the circulation flow path 195 that satisfies the expression (10). The suction pressure Pv can be increased compared to the flow path resistance up to E. Therefore, the circulation pump 110 can circulate the liquid through the circulation flow path 195 while ensuring a predetermined flow rate Q. Further, by providing the branch channel 210 on the liquid channel 190, the film pack 160 can be easily detached from the fluid circulation apparatus 100, and assembly and maintenance can be easily performed. In addition, since the branch channel 210 includes the movable portion 216, the first liquid Lq1 is prevented from leaking outside from the branch channel, and further, the first liquid Lq1 is prevented from being diffused. Can do.

C. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.
(C1) Modification 1:
In the above embodiment, the film pack 160 is provided in the liquid flow path 190 as the circulation flow path 195, but the above-described limitation of the separation distance h (formula (7), formula (9), formula (10)). The film pack 160 may be installed at another position as long as it satisfies the requirement. For example, the pump suction flow path 144 as the circulation flow path 195 may be provided. FIG. 7 is an explanatory diagram illustrating the fluid circulation device 100 according to the first modification. As shown in the figure, the flow path case 140 is provided with a flow path (hereinafter also referred to as a communication flow path 145) that communicates with the pump suction flow path 144, and the film pack 160 is connected to the pump suction flow path 144 via the communication flow path 145. By connecting, the film pack 160 can be provided in the pump suction flow path 144. By doing in this way, the circulation pump 110 and the film pack 160 can be made into an integral structure, and compactness and improvement in durability can be realized.

(C2) Modification 2:
In the above-described embodiment, the film pack 160 or the branch flow path 210 is used as the fluid storage unit. However, other fluid storage units may be employed without being limited thereto. For example, a fluid container such as a diaphragm (diaphragm pump), a syringe, or a bellows can be employed. Similarly to the above-described embodiment, each fluid storage chamber is connected to the liquid flow path 190 via a connection member, or connected to the communication flow path communicating with the pump suction flow path 144 described in the first modification. Can be realized. Even if it does in this way, the effect similar to the said Example can be acquired.

(C3) Modification 3:
In the above-described embodiment, the tubular circulation channel 195 having a circular cross-sectional area is adopted as an embodiment of the circulation channel. However, the present invention is not limited to this, and various circulation channels can be employed. In this case, the restriction of the separation distance h can be derived by calculating the flow resistance R per unit length of the circulation flow path to be adopted by a predetermined calculation and applying it to the flow resistance R of Expression (7). it can. And the film pack 160 is provided in the position of the circulation flow path 195 which satisfy | fills the restriction | limiting of the derived separation distance h. By doing in this way, the circulation pump 110 can circulate the fluid by ensuring the flow rate Q in the circulation channels of various shapes.

  In the above embodiment, the suction pressure Pv of the circulation pump 110 is 10 [kpa], the channel diameter d of the liquid channel 190 is 0.0005 [mm], and the viscosity of the liquid (water) μ = 0.001 [ It is assumed that the film pack 160 is provided by adopting the separation distance h that satisfies the expression (10) derived as Pa · s] and the flow rate Q = 5 [ml / min]. However, the fluid circulation device 100 may be configured by changing the type of the circulation pump to set the suction pressure Pv to another value, or adopting other values as the flow path diameter d, viscosity μ, and flow rate Q. Good. In this case, by applying the values of the adopted suction pressure Pv, flow path diameter d, viscosity μ, and flow rate Q to the equation (9), a specific limit of the separation distance h is derived and derived. By installing the film pack 160 at a position that satisfies the separation distance h, the circulation pump 110 can ensure the flow rate Q and circulate the fluid through the circulation channel 195.

(C4) Modification 4:
In the above embodiment, the fluid circulation device 100 is used for cooling the piezoelectric actuator 34 of the fluid ejection device 20 (water jet knife). In medical devices that require particularly high safety, the fluid circulation device 100 according to the above-described embodiments and modifications can be applied to various medical devices in order to ensure stable circulation efficiency. For example, the fluid circulation device 100 may be used to adjust the temperature of a motor unit of a medical drill or an ultrasonic generator of an ultrasonic scaler that removes tartar by ultrasonic waves. Further, the fluid circulation device 100 is not limited to the case where it is used for cooling the heat generating portion, but may be used when heating an object. For example, it can be used when a part of a human body is heated or kept warm. In this case, it can be realized by providing the fluid circulation device 100 with a separate heating unit for heating the circulating fluid.

(C5) Modification 5:
In the above embodiment, liquid, particularly water, is employed as the fluid circulating through the fluid circulation device 100, but various fluids can be employed without being limited thereto. For example, nitrogen or carbon dioxide may be employed as the gas. In addition to water and oil, propylene glycol, ethylene glycol, glycerin, and aqueous solutions thereof may be used as the liquid. In this case, by applying the viscosity value of the employed liquid as the viscosity μ, the same effect as in the above embodiment can be obtained.

(C6) Modification 6:
In the second embodiment, the branch flow path 210 includes the movable portion 216, but a branch flow path that does not include the movable portion may be employed. By doing in this way, the structure of a branch flow path can be simplified.

(C7) Modification 7:
In the above-described embodiment, the piezoelectric element is employed as the operating element. However, the present invention is not limited thereto, and various elements may be employed. For example, driving elements such as electrostrictive elements, electromagnetic actuators, electrostatic actuators, and dielectric polyactuators can be used. Even if these driving elements are employed, the same effects as in the above-described embodiment can be obtained. In the above-described embodiment, the stacked type is used as the piezoelectric element, but in addition, a piezoelectric element of a single crystal, a monomorph type, or a bimorph type piezoelectric element may be used.

(C8) Modification 8:
In the above embodiment, the check valve 148 is employed as the fluid resistance element in the above embodiment, but not limited thereto, various fluid resistance elements can be employed. FIG. 8 is an explanatory diagram showing fluid resistance elements that can be employed. The illustrated fluid resistance element (A) is a check valve installed at a position different from the first embodiment. The fluid resistance element (B) suppresses the flow of liquid from the pump chamber 130 to the liquid chamber 146 without using a check valve. The fluid resistance element (C) has a configuration in which the check valve 148 is not installed in the above embodiment. Even if it is a fluid resistance element (C), the flow of the liquid from the pump chamber 130 to the liquid chamber 146 can be suppressed with the shape. Further, since the fluid resistance element (B) and the fluid resistance element (C) do not have a movable portion like the check valve 148, durability can be improved.

DESCRIPTION OF SYMBOLS 10 ... Fluid ejecting system 20 ... Fluid ejecting apparatus 30 ... Pulsation generating part 32 ... Fluid chamber 34 ... Piezoelectric actuator 36 ... Fluid ejecting pipe 38 ... Lower case 39 ... Upper case 40 ... Fluid container 42 ... Supply pump 44 ... Connection tube 46 ... Connection tube 100 ... Fluid circulation device 110 ... Circulation pump 112 ... Piezoelectric element case 114 ... Piezoelectric element 116 ... Reinforcing plate 118 ... Diaphragm 120 ... Ring member 130 ... Pump chamber 140 ... Flow path case 140C ... Concave part 142 ... Pump discharge flow path 144 DESCRIPTION OF SYMBOLS ... Pump suction flow path 146 ... Liquid chamber 148 ... Check valve 160 ... Film pack 162 ... Connection member 162a ... Communication hole 164 ... Film 166 ... Opening port member 190 ... Liquid flow path 195 ... Circulation flow path 200 ... Fluid circulation apparatus 210 ... Branch channel 214 ... High viscosity gel fluid 216 ... Moving part 218 ... Vent 230 ... Sensor Q ... Flow rate S ... Flow path start point E ... Flow path end point h ... Separation distance Lq1 ... First liquid Lq2 ... Second liquid

Claims (9)

A fluid circulation device comprising:
A pump chamber that performs a pump operation for sucking and discharging a fluid; and
An inflow channel which is a channel through which fluid flows into the pump chamber;
A fluid resistance element that suppresses or inhibits the flow of the fluid from the pump chamber toward the inflow channel;
A fluid outlet from the pump chamber;
A circulation channel that is a tubular channel through which the fluid circulates from the discharge port to the inflow channel;
A fluid storage section provided on the circulation flow path and configured to store the fluid when the pump operation is stopped and to supply the stored fluid as a part of the circulating fluid when the pump is operated; Prepared,
Let Q be the flow rate of the fluid circulating through the circulation channel during the pump operation,
R is a flow path resistance per unit length of the circulation flow path from the fluid containing part to the inflow flow path side end during the pump operation,
When the suction pressure, which is the pressure at which the pump chamber sucks the fluid, is Pv (Pv> 0),
The fluid container is provided at a position of a length h that satisfies the relationship of the formula (1) from the end on the inflow channel on the circulation channel.

The fluid circulation device according to claim 1,
The viscosity of the fluid is μ,
When the diameter of the circulation channel is d,
The fluid accommodating portion is provided at a position of a length h that satisfies the relationship of Expression (2) from an end portion on the inflow channel on the circulation channel.

The fluid circulation device according to claim 1 or 2,
The circulation channel includes a tubular suction channel formed integrally with the inflow channel, and a tubular fluid channel connecting the suction channel and the discharge pipe line,
The fluid storage device is provided by branching from the suction flow path. The fluid circulation device according to any one of claims 1 to 3,
The fluid storage unit includes a fluid storage chamber that stores the fluid used for the supply, and is deformable according to the amount of the fluid stored in the interior. The fluid circulation device according to claim 4,
The fluid storage chamber is a pack formed by sealing a film in a bag shape. The fluid circulation device according to any one of claims 1 to 5,
The fluid storage device is a branch channel branched from the circulation channel. The fluid circulation device according to claim 6,
A sealing material that seals the accommodated fluid and moves according to a pressure difference between the pressure of the fluid in the branch channel and atmospheric pressure is disposed inside the branch channel. A fluid circulation device. The fluid circulation device according to claim 7,
The fluid is a first liquid;
A second liquid that can be phase-separated from the first liquid is sealed between the first liquid and the sealing material inside the branch flow path,
The fluid circulation device, wherein the heat of vaporization of the second liquid is greater than the heat of vaporization of the first liquid.   A medical device using the fluid circulation device according to any one of claims 1 to 8.

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