JP6015042B2 - Fluid circulation device - Google Patents

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, there is a problem that the fluid cannot be circulated stably because the pressure or the like during the circulation of the fluid is not taken into consideration.

JP-A-8-242463

  The present invention has been made to solve at least a part of the conventional problems described above, and an object of the present invention is to provide a technique capable of stably circulating 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.
[Embodiment 1] A fluid circulation device, wherein a pump chamber that performs an operation of changing a volume; an inlet channel that is an inflow path of fluid to the pump chamber; and the fluid that travels from the pump chamber to the inlet channel A fluid resistance element that suppresses or inhibits the flow of the fluid; an outlet channel that is a fluid outlet from the pump chamber; and a circulation channel that is a channel through which the fluid circulates from the outlet channel to the inlet channel And a fluid storage section for storing the fluid of the volume Vb when the pump chamber is not operating and for supplying the stored fluid as a part of the circulating fluid when the pump chamber is operating. The amount of increase in the volume of the circulation channel during operation of the pump chamber is ΔVe; the amount of decrease in the volume of the fluid due to a change in the pressure of the fluid that occurs during operation of the pump chamber is ΔVp; Circulator A predetermined temperature within the temperature range to be used is defined as a reference temperature Ts; a temperature at which the volume of the fluid is smallest among temperature ranges in which the fluid circulation device is utilized is defined as a temperature Tmin; When the decrease amount of the volume of the fluid when changing from the temperature Ts to the temperature Tmin is ΔVt; the volume Vb satisfies the relationship of Vb ≧ ΔVe + ΔVp + ΔVt at the reference temperature Ts; A fluid storage chamber for storing the fluid used for the supply; a volume of the fluid storage chamber can be changed according to an amount of the fluid stored in the interior; a fluid circulation device.
If negative pressure advances on the suction side of the pump chamber, stable circulation of fluid becomes difficult. The negative pressure on the suction side of the pump chamber is caused by a lack of fluid circulating in the flow path. According to the configuration of the fluid circulation device, in consideration of the deformation of the circulation flow path, the decrease in the volume of the fluid due to the compression, and the decrease in the volume of the fluid due to the temperature change, which cause the shortage of the fluid, The volume Vb of the fluid accommodated by the fluid accommodating portion during non-operation is determined, and the fluid accommodating portion supplies the accommodated fluid as part of the circulating fluid during operation of the pump chamber. Thus, the negative pressure on the suction side of the pump chamber does not progress, and the fluid can be circulated stably. In addition, according to this configuration, since the liquid storage chamber can store the fluid when the pump chamber is not operating and can supply the fluid when the pump chamber is operating, the liquid storage chamber can sufficiently compensate for the shortage of circulating fluid, Negative pressure on the suction side of the pump chamber can be suppressed, and the fluid can be circulated stably.

[Application Example 1]
A fluid circulation device comprising:
A pump chamber that performs the operation of changing the volume;
An inlet channel which is a fluid inflow path to the pump chamber;
A fluid resistance element that inhibits or inhibits the flow of fluid from the pump chamber to the inlet channel;
An outlet channel that is an outlet of fluid from the pump chamber;
A circulation channel that is a channel through which the fluid circulates from the outlet channel to the inlet channel;
A fluid storage section that stores the fluid of volume Vb when the pump chamber is not operating, and supplies the stored fluid as part of the circulating fluid when the pump chamber is operating;
ΔVe is the amount of increase in the volume of the circulation channel during the operation of the pump chamber,
ΔVp is a decrease in volume of the fluid due to a change in the pressure of the fluid that occurs during operation of the pump chamber,
A predetermined temperature within a temperature range in which the fluid circulation device is used is set as a reference temperature Ts,
Of the temperature range in which the fluid circulation device is used, the temperature at which the volume of the fluid is minimized is defined as a temperature Tmin.
When the amount of decrease in the volume of the fluid when the temperature of the fluid changes from the reference temperature Ts to the temperature Tmin is ΔVt,
The volume Vb is the reference temperature Ts.
Vb ≧ ΔVe + ΔVp + ΔVt
Fluid circulation device that satisfies the relationship of
If negative pressure advances on the suction side of the pump chamber, stable circulation of fluid becomes difficult. The negative pressure on the suction side of the pump chamber is caused by a lack of fluid circulating in the flow path. According to the configuration of the fluid circulation device, in consideration of the deformation of the circulation flow path, the decrease in the volume of the fluid due to the compression, and the decrease in the volume of the fluid due to the temperature change, which cause the shortage of the fluid, The volume Vb of the fluid accommodated by the fluid accommodating portion during non-operation is determined, and the fluid accommodating portion supplies the accommodated fluid as part of the circulating fluid during operation of the pump chamber. Thus, the negative pressure on the suction side of the pump chamber does not progress, and the fluid can be circulated stably.

[Application Example 2]
A fluid circulation device according to Application Example 1,
Of the temperature range in which the fluid circulation device is used, the temperature at which the volume of the fluid is the largest is the temperature Tmax,
When the amount of increase in the volume of the fluid when the temperature of the fluid changes from the reference temperature Ts to the temperature Tmax is ΔVh,
The fluid storage portion can further store a fluid of ΔVh at the temperature Tmax when the pump chamber is not in operation.
Fluid circulation device.
According to this configuration, even when the temperature of the liquid changes to the temperature Tmax and the volume of the liquid increases, the increase amount ΔVh of the volume of the liquid can be absorbed by the fluid storage unit.

[Application Example 3]
The fluid circulation device according to Application Example 1 or Application Example 2,
The fluid storage unit includes a fluid storage chamber that stores the fluid used for the supply inside,
The volume of the fluid storage chamber can be changed according to the amount of the fluid stored in the interior.
Fluid circulation device.
According to this configuration, the liquid storage chamber can store the fluid when the pump chamber is not operating and can supply the fluid when the pump chamber is operating. It is possible to suppress negative pressure on the suction side and circulate the fluid stably.

[Application Example 4]
A fluid circulation device according to Application Example 3,
The fluid storage chamber is a pack formed in a bag shape,
Fluid circulation device.
According to this configuration, the fluid storage chamber can be easily realized, and the cost can be reduced.

[Application Example 5]
The fluid circulation device according to any one of Application Example 1 to Application Example 4,
The fluid storage part includes a branch channel branched from the circulation channel,
Fluid circulation device.
According to this configuration, the branch flow path can accommodate the fluid when the pump chamber is not in operation and can supply the fluid when the pump chamber is in operation. It is possible to suppress negative pressure on the suction side and circulate the fluid stably.

[Application Example 6]
The fluid circulation device according to Application Example 5,
A sealing material that seals the accommodated fluid and moves according to a pressure difference between the pressure of the fluid and the atmospheric pressure inside the branch channel is disposed inside the branch channel. ing,
Fluid circulation device.
According to this structure, since the sealing material is arrange | positioned inside the branch flow path, it can suppress that a fluid flows out outside from a branch flow path.

[Application Example 7]
The fluid circulation device according to Application Example 6,
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 heat of vaporization of the second liquid is greater than the heat of vaporization of the first liquid.
Fluid circulation device.
According to this configuration, vaporization of the first liquid can be suppressed.

[Application Example 8]
A medical device using the fluid circulation device according to any one of Application Example 1 to Application Example 7.
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 method and apparatus for circulating fluid, a fluid circulation system, an integrated circuit for realizing the functions of the method or apparatus, a computer program, a recording medium on which the computer program is recorded, and the like.

It is explanatory drawing which shows schematic structure of the fluid injection system as one Example of this invention. 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 a schematic diagram which shows the mode of the change of the volume of the liquid by a temperature change. It is explanatory drawing for demonstrating the increase amount (DELTA) Ve of the volume of a liquid flow path. It is explanatory drawing which shows the change of the volume of a liquid flow path typically. It is explanatory drawing which shows the relationship between the temperature of a liquid, and the volume of a liquid in a graph format. It is explanatory drawing which shows typically the mode at the time of operation | movement of a fluid circulation apparatus. It is a schematic diagram which shows roughly the structure of the cross section of the fluid circulation apparatus in 2nd Example. It is a schematic diagram which shows roughly the structure of the cross section of the fluid circulation apparatus in 3rd Example. It is a schematic diagram which shows roughly the fluid circulation apparatus in 4th Example. It is explanatory drawing which showed the fluid resistance element which can be employ | adopted.

Next, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A1. Device configuration:
A2. Circulation pump operation:
A3. Composition of film pack:
A4. About the volume of liquid contained in the film pack:
A5. Regarding the increase amount ΔVe of the volume of the liquid flow path:
A6. About the decrease amount ΔVp of the liquid volume due to the change in pressure:
A7. Regarding the decrease amount ΔVt of the volume of the liquid due to the change in temperature:
A8. Summary:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Variations:

A. First embodiment:
A1. Device configuration:
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 supplies water stored in the fluid container 40 to the pulsation generating unit 30, and a fluid container. 40 and a connection tube 44 that connects the supply pump 42 and a connection tube 46 that connects the supply pump 42 and the pulsation generator 30.

  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 ejection pipe 36 through which water pulsated by the piezoelectric actuator 34 passes, a lower case 38 that accommodates the piezoelectric actuator 34 therein, 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. The fluid circulation device 100 includes a circulation pump 110, a liquid passage 190 that is a circulation passage connected to the circulation pump 110 at both ends, and the circulation pump 110. And a control unit 196 for controlling. In this embodiment, the circulation pump 110 and the liquid flow path 190 constitute a closed circulation path. That is, the fluid in the fluid circulation device 100 circulates in a state where it is not in contact with outside air.

  The liquid channel 190 is a tube having pressure resistance and flexibility. As a tube having pressure resistance and flexibility, 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 is applicable. However, it is not particularly limited to these. In this embodiment, a silicon tube is employed as the liquid flow path 190. The liquid flow path 190 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 that does not intentionally have a portion where the circulating fluid is in contact with the outside (atmosphere).

  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 channel 144 that is connected to the other end of the liquid channel 190 and guides the liquid supplied from the liquid channel 190 to the liquid chamber 146. In the present embodiment, a discharge side buffer 143 having a larger cross-sectional area than the pump discharge flow path 142 is formed in the middle of the pump discharge flow path 142. The discharge side buffer 143 has a function of reducing the pulsation of the liquid discharged from the pump chamber 130.

  One end of the liquid chamber 146 opens to the upper surface side of the flow path case 140 (the side opposite to the side facing the piezoelectric element case 112), and the other end communicates with the pump chamber 130, and faces the pump chamber 130 side. Thus, the diameter is reduced (so that the cross-sectional area is reduced). A pump suction flow path 144 is connected to a portion where the diameter of the liquid chamber 146 is reduced. A check valve 148 is provided at the end of the liquid chamber 146 on the pump chamber 130 side. 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.

  The film pack 160 is airtightly connected to the opening of the liquid chamber 146 formed on the upper surface side of the flow path case 140 via a connecting member 162. 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. In the present embodiment, the film pack 160 is detachable from the flow path case 140.

  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. Circulation pump operation:
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 a 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 is used to adjust the inside of the liquid channel 190 to an appropriate pressure in the operating state. The amount (volume) of the liquid stored in the film pack 160 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 flow path 190 is pushed out and returned to the circulation pump 110. The liquid flows into the film pack 160 through the pump suction channel 144. Here, the film pack 160 is formed of a flexible film, and is attached not in a completely stretched state filled with a liquid but in a state in which it still has a margin for swelling. Therefore, even if the liquid returned from the liquid flow path 190 flows into the film pack 160, the film pack 160 swells to increase the pressure in the film pack 160 or the liquid chamber 146 communicating with the film pack 160. It is suppressed.

  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 inside of the pump chamber 130 becomes negative pressure, the check valve 148 is opened, and the liquid is sucked into the pump chamber 130 from the liquid chamber 146. 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 to be larger than the flow resistance of the liquid chamber 146 and 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. The liquid chamber 146 communicates with the film pack 160, and the liquid in the film pack 160 flows into the pump chamber 130 without stagnation, so that the liquid chamber 146 is unlikely to have a negative pressure.

  After the pump chamber 130 whose volume has been recovered in this way is filled with the liquid from the liquid chamber 146, when the piezoelectric element 114 expands again due to an increase in the drive voltage, as shown in FIG. The liquid pressurized inside 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. Composition 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 opening member 166 on the other end side, and air-tightly bonding the periphery by thermocompression bonding or the like.

  FIG. 4B shows a film pack 160 formed by bonding a pair of film 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 when the liquid is not contained therein.

  On the other hand, when the liquid flows into the film pack 160 through the communication hole 162a of the connecting member 162, as shown in FIG. 4C, the pair of film 164 separates from each other so that the film pack 160 swells (volume). 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 film 164 approaches each other and the film pack 160 is deflated (the volume is reduced). As described above, the film pack 160 can be deformed in accordance with the amount of liquid accommodated therein.

  FIG. 4D illustrates the structure of the film 164 used for the film pack 160. The illustrated film 164 has a multi-layer structure. Polypropylene (PP) having excellent liquid resistance is bonded to both sides of an aluminum foil (AL), and further, polyethylene having excellent impact resistance is provided on both sides thereof. 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 increased and the gas barrier property can be improved. The film pack 160 having such a configuration is excellent in heat resistance, can be handled at a high temperature (for example, 150 ° C.), has flexibility, and can be easily deformed. Moreover, the film pack 160 can be easily formed by thermocompression bonding in addition to realizing weight reduction.

The structure of the film 164 used in the film pack 160 is not limited to the structure shown in FIG. 4D. For example, instead of an aluminum foil as an intermediate layer, an 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. About the volume of liquid contained in the film pack:
In the present embodiment, the film pack 160 stores a predetermined volume of liquid when the pump chamber 130 is not operating (stopped), and circulates the stored liquid when the pump chamber 130 is operating. As part of the supply. Hereinafter, this reason will be described.

  When the pump chamber 130 is operated and the circulation of the liquid is started, a pressure difference is generated between the discharge side and the suction side of the circulation pump 110 (that is, a pressure gradient is generated). When a pressure difference occurs between the discharge side and the suction side, the liquid flow path 190 is deformed, and the liquid volume in the liquid flow path 190 is biased. If the operation of the pump chamber 130 is continued as it is, the pressure on the suction side of the circulation pump 110 becomes a negative pressure, and the pump characteristics deteriorate.

  In addition, due to the discharge pressure of the circulation pump 110, the liquid is compressed on the discharge side of the circulation pump 110, and the volume of the liquid is reduced according to the discharge pressure of the circulation pump 110 and the liquid compression rate. As a result, the volume of the liquid is insufficient with respect to the volume of the flow path, and the negative pressure further proceeds.

  Further, when the temperature around the fluid circulation device 100 changes and the temperature of the liquid in the flow path changes, the volume of the liquid changes.

  FIG. 5 is a schematic diagram showing how the volume of the liquid changes due to temperature changes. FIG. 5 (A) shows the state of the liquid in the channel at normal temperature (for example, 20 ° C.), and FIG. 5 (B) shows the state of the liquid in the channel at high temperature. FIG. 5C shows the state of the liquid in the channel at a low temperature. When the liquid temperature changes, the liquid expands or contracts depending on the liquid expansion coefficient, creating a difference between the volume of the flow path and the volume of the liquid, and the penetration of the liquid out of the flow path. (FIG. 5 (B)) and the entry of air or the like from outside the flow path may occur (FIG. 5 (C)). In particular, when the liquid in the flow path contracts, the liquid is insufficient with respect to the volume of the flow path, and the negative pressure may be further increased.

  As a result, the negative pressure advances on the suction side of the circulation pump 110, and it becomes difficult to circulate the liquid stably. Therefore, in this embodiment, the film pack 160 suppresses the shortage of the liquid in the flow path by supplying the contained liquid as a part of the circulating fluid during the operation of the pump chamber 130, and the circulation pump 110. It suppresses that the pressure in the suction side becomes negative pressure.

Next, an examination will be made as to how much volume of liquid the film pack 160 contains when the pump chamber 130 is not in operation, so that the shortage of liquid can be sufficiently compensated and negative pressure can be suppressed. The causes of the negative pressure described above are summarized as follows.
Cause 1. Deformation of liquid flow path 190 Cause 2. Reduced liquid volume due to compression Cause 3. Liquid volume reduction due to temperature change

  Therefore, in this embodiment, corresponding to the cause 1, the increase amount of the volume of the liquid flow path 190 during the operation of the pump chamber 130 is set to ΔVe. Then, corresponding to cause 2, the amount of decrease in the volume of the liquid due to the change in the pressure of the liquid that occurs during the operation of the pump chamber 130 is denoted by ΔVp. Further, corresponding to cause 3, a predetermined temperature within the temperature range in which the fluid circulation device 100 is used is set as the reference temperature Ts, and the volume of the liquid is the smallest in the temperature range in which the fluid circulation device 100 is used. Let the temperature be the temperature Tmin, and let ΔVt be the amount of decrease in the volume of the liquid when the temperature of the liquid changes from the reference temperature Ts to the temperature Tmin.

As described above, considering the three causes, in this embodiment, the volume Vb of the liquid stored in the film pack 160 when the pump chamber 130 is not in operation is set to satisfy the following expression (1) at the reference temperature Ts. Yes.
Vb ≧ ΔVe + ΔVp + ΔVt (1)
Below, the specific calculation method of (DELTA) Ve, (DELTA) Vp, and (DELTA) Vt is demonstrated.

A5. Regarding the increase amount ΔVe of the volume of the liquid flow path:
An example of a method for calculating the volume increase amount ΔVe of the liquid channel 190 will be described. In this specification, it is assumed that ΔVe has a positive value when the volume of the liquid flow path 190 increases.

  FIG. 6 is an explanatory diagram for explaining the increase amount ΔVe of the volume of the liquid channel 190. As shown in FIG. 6A, in this embodiment, the film pack 160 is connected to the circulation pump 110, and the pressure of the liquid in the liquid flow path 190 before the operation of the fluid circulation device 100 is the atmospheric pressure P0. Consider a model in which the length of the liquid channel 190 is L.

  In this model, when the circulation pump 110 starts operating at the discharge pressure Ps, as shown in FIG. 6B, the pressure on the discharge side of the circulation pump 110 is Ps, and the pressure on the suction side of the circulation pump 110 is Since the liquid is supplied from the film pack 160 and the negative pressure is suppressed, the atmospheric pressure P0 is obtained.

  In the liquid channel 190, pressure loss occurs due to channel resistance, so the pressure of the liquid in the liquid channel 190 decreases from the discharge side of the circulation pump 110 toward the suction side. In this embodiment, it is assumed that the pressure of the liquid in the liquid flow path 190 decreases linearly from the discharge side of the circulation pump 110 toward the suction side. And since the liquid flow path 190 deform | transforms according to the pressure of the liquid in the liquid flow path 190, it can be assumed that it deform | transforms like FIG.6 (B).

  As shown in FIG. 6C, assuming that the liquid flow path 190 is a cylinder having an inner diameter 2a (inner wall radius a) and an outer diameter 2b (outer wall radius b), the internal pressure p is set at a position of radius r. The radial displacement u in the case of receiving can be expressed by the following equation (A1) from the equation of displacement of the thick-walled cylinder that receives the internal pressure.

  Here, ν is Poisson's ratio and E is Young's modulus. Substituting the radius a of the inner wall of the liquid channel 190 for r in the above equation (A1) to obtain the displacement u (a) of the inner wall of the liquid channel 190, the following equation (A2) is obtained.

  Here, c is a constant. The amount of increase ΔVedl of the volume of the liquid channel 190 per unit length due to the change of the radius of the inner wall of the liquid channel 190 from a to a + u (a), where L is the axial length of the liquid channel 190, The following formula (A3) is obtained.

  In the above formula (A3), when the value of u (a) ^ 2 is small enough to be ignored, u (a) ^ 2 can be omitted. In the above formula (A3), when u (a) ^ 2 is omitted and the above formula (A2) is substituted, the following formula (A4) is obtained. (In this specification, the symbol “^” means power.)

  Further, when the value representing the discharge pressure of the circulation pump 110 as an absolute pressure is Ps and the value representing the atmospheric pressure as an absolute pressure is P0, the pressure at the position x of the liquid flow path 190 is represented as an absolute pressure. The value P (x) is expressed by the following equation (A5) when the pressure loss due to the channel resistance is linearly approximated (FIG. 6B).

  Since the pressure affecting the deformation of the liquid flow path 190 is a difference from the atmospheric pressure P0, when p (x) = P (x) −P0 and ps = Ps−P0, the above formula (A5) is The following formula (A6) is obtained.

  In the present specification, the absolute pressure is represented by a capital letter P, and the relative pressure with the atmospheric pressure as a reference (0) is represented by a small letter p. Substituting the above formula (A6) into the above formula (A4) and integrating x in the range from 0 to L, the following formula (A7) is obtained, and the increase amount ΔVe of the volume of the entire liquid channel 190 is obtained. Can do.

  In the above formula (A3), when the value of u (a) ^ 2 is not ignored, the above formula (A7) becomes the following formula (A8).

Here, as an example, if the following specific values are substituted into the formula (A7), ΔVe becomes 0.021 cc.
Inner diameter 2a of liquid flow path 190: 0.5 mm
The outer diameter 2b of the liquid channel 190: 1.0 mm
Length L of liquid flow path 190: 2000 mm
Young's modulus E of the liquid flow path 190: 5 MPa
Poisson's ratio ν of liquid flow path 190: 0.46
Discharge pressure ps of circulation pump 110: 0.5 MPa

  Further, when the above specific value is substituted into the formula (A8), ΔVe becomes 0.022 cc. In this case, since the error is about 5%, it can be understood that ΔVe may be calculated while ignoring the minute term. However, in the above specifications, when the discharge pressure of the circulation pump 110 is 10 times 5.0 MPa, ΔVe calculated from the equation (A7) is 0.21 cc, and ΔVe calculated from the equation (A8) is 0. It becomes 36cc. Therefore, when the error becomes large, such as when the discharge pressure of the circulation pump 110 is large, ΔVe is preferably calculated from the above equation (A8).

A6. About the decrease amount ΔVp of the liquid volume due to the change in pressure:
Next, an example of a method for calculating the decrease amount ΔVp of the liquid volume due to a change in pressure will be described. In this specification, it is assumed that ΔVp has a positive value when the volume of the liquid is reduced.

  FIG. 7 is an explanatory diagram schematically showing a change in the volume of the liquid flow path 190. In FIG. 7, the liquid flow path 190 is depicted as being disconnected from the suction side of the circulation pump 110. FIG. 7A shows a state before the operation of the circulation pump 110, and FIG. 7B shows a state when the circulation pump 110 is in operation.

  As shown in FIG. 7A, the discharge-side buffer 143 has a columnar shape with a diameter D, a length h, and a volume V1, and the length of the liquid channel 190 is L. Further, the radius of the inner wall of the liquid channel 190 before the operation of the circulation pump 110 is a, and the volume of the liquid channel 190 is Vtu.

  Further, as shown in FIG. 7B, when the circulation pump 110 is in operation, the liquid flow path 190 is deformed, so that the radius of the portion of the inner wall of the liquid flow path 190 connected to the discharge side buffer 143 is a + u (a), and the volume of the liquid flow path 190 is V2 (= Vtu + ΔVe). The discharge pressure of the circulation pump 110 is Ps, and the liquid in the discharge side buffer 143 is uniformly applied with the pressure Ps. A pressure gradient is generated in the liquid in the liquid flow path 190. In the following, for this model, a decrease amount ΔVp of the volume of the liquid due to a change in pressure is calculated.

  In general, when the liquid compressibility is κ and the liquid volume at atmospheric pressure (absolute pressure P0) is V0, the amount of decrease ΔVp in the liquid volume when the pressure (relative pressure) is p is given by It is represented by the formula (B1).

  Here, a decrease amount ΔVp of the volume of the liquid during the operation of the circulation pump 110 is obtained. When the discharge pressure of the circulation pump 110 is ps and ΔVp is calculated separately for the liquid in the discharge-side buffer 143 and the liquid in the liquid flow path 190, the following equation (B2) is obtained.

  Here, VtudL is the volume of the liquid per unit length of the liquid channel 190 before deformation. Note that p (x) in the above equation (B2) can be obtained by substituting the above equation (A6), and ΔVedL can be obtained by substituting the above equation (A3). In this way, the decrease amount ΔVp of the volume of the liquid due to a change in pressure during the operation of the circulation pump 110 can be obtained.

Here, as an example, if the following specific values are substituted into the formula (B2), ΔVp becomes 0.00027 cc (0.27 mm ³ ).
Diameter D of discharge side buffer 143: 5 mm
Length h of discharge side buffer 143: 50 mm
Inner diameter 2a of liquid flow path 190: 0.5 mm
The outer diameter 2b of the liquid channel 190: 1.0 mm
Length L of liquid flow path 190: 2000 mm
Young's modulus E of the liquid flow path 190: 5 MPa
Poisson's ratio ν of liquid flow path 190: 0.46
Discharge pressure ps of circulation pump 110: 0.5 MPa
Liquid (water) compressibility κ: 0.45 GPa ⁻¹

When ΔVp is obtained for a model that does not include the discharge-side buffer 143 (the third embodiment described below), the first term on the right side of the equation (B2) is set to 0, and the above specific value is expressed by the equation ( B2) may be substituted, and ΔVp is 0.00006 cc (0.06 mm ³ ).

A7. Regarding the decrease amount ΔVt of the volume of the liquid due to the change in temperature:
Next, an example of a method for calculating the decrease amount ΔVt of the volume of the liquid due to a change in temperature will be described. In the present specification, it is assumed that ΔVt has a positive value when the volume of the liquid decreases.

  First, a predetermined temperature within a temperature range in which the fluid circulation device 100 is used is defined as a reference temperature Ts, a liquid volume at the reference temperature Ts is defined as Vs, and a liquid volume in the temperature range in which the fluid circulation device 100 is utilized. Is the temperature Tmin, and the volume of the liquid at the temperature Tmin is Vmin. When the liquid temperature changes from the reference temperature Ts to the temperature Tmin, the decrease amount ΔVt of the liquid volume is expressed by the following equation (C1 ).

  Here, when the expansion coefficient of the liquid is β, the volume Vmin of the liquid at the temperature Tmin is expressed by the following formula (C2).

  When the above formula (C2) is substituted into the above formula (C1), ΔVt is represented by the following formula (C3).

  As Vs, a value obtained by adding the volume of the liquid contained in the film pack 160 to the volume of the liquid existing in the liquid flow path 190 or the circulation pump 110 when the pump chamber 130 is not operating is used. It is preferable. However, when the volume of the liquid stored in the film pack 160 is very small compared to the volume of the liquid existing in the liquid flow path 190 or the circulation pump 110, ΔVt is calculated. The volume of the liquid contained in the film pack 160 may be ignored. Similarly, in the case of calculating ΔVh described later, the volume of the liquid stored in the film pack 160 is similarly small compared to the volume of the liquid existing in the liquid flow path 190 and the circulation pump 110. In some cases, the volume of the liquid contained in the film pack 160 may be ignored when calculating ΔVt. Hereinafter, an example of ΔVt is calculated by substituting a specific value into the above formula (C3).

FIG. 8 is an explanatory diagram showing the relationship between the temperature of the liquid and the volume of the liquid in a graph format. In FIG. 8, the temperature range in which the fluid circulation device 100 is used is set to 0 ° C. to 100 ° C., and the reference temperature Ts is set to 20 ° C. For example, the reference temperature Ts is preferably set to the temperature of the environment in which the fluid circulation device 100 is manufactured. Vs was 2.000 cc, and the expansion coefficient β of the liquid (water) at 20 ° C. was 2.1 × 10 ⁻⁴ / ° C. Although the expansion coefficient β varies depending on the temperature, it is assumed here that the expansion coefficient β is constant in the temperature range of 0 ° C. to 100 ° C. When these values are substituted into the formula (C3), ΔVt becomes 0.0084 cc. Note that ΔVh, Vmax, and Tmax shown in FIG. 8 will be described later.

  FIG. 9 is an explanatory diagram schematically showing a state during operation of the fluid circulation device 100. FIG. 9 shows an example in which the film pack 160 is connected to the liquid flow path 190. Further, the size of the film pack 160 depicted in FIG. 9 indicates the amount (volume) of the liquid stored in the film pack 160. In the example of FIG. 9, the film pack 160 contains a liquid having a volume equal to or larger than ΔVe + ΔVp + ΔVt at the reference temperature Ts.

  FIG. 9A shows a state during operation of the fluid circulation device 100 at the temperature Tmin. In FIG. 9A, the volume of the liquid in the flow path decreases due to the compression of the liquid due to the temperature change, and the liquid stored in the film pack 160 decreases so as to compensate for the decrease. FIG. 9B shows a state during operation of the fluid circulation device 100 at the reference temperature Ts. FIG. 9C shows a state during operation of the fluid circulation device 100 at the temperature Tmax. In FIG. 9C, the volume of the liquid in the flow path increases due to the expansion of the liquid due to the temperature change, and the liquid stored in the film pack 160 increases so as to absorb the increase. .

A8. Summary:
As described above, in this embodiment, the volume Vb of the liquid stored in the film pack 160 when the pump chamber 130 is not operating satisfies the following formula (1) at the reference temperature Ts. The shortage of liquid can be sufficiently compensated, negative pressure on the suction side of the circulation pump 110 can be suppressed, and the liquid can be circulated stably.
Vb ≧ ΔVe + ΔVp + ΔVt (1)

  As shown in FIG. 8, the temperature at which the volume of the liquid becomes the largest in the temperature range in which the fluid circulation device 100 is used is the temperature Tmax (100 ° C. in FIG. 8), and the volume of the liquid at the temperature Tmax is Vmax. And the amount of increase in the volume of the liquid when the temperature of the liquid changes from the reference temperature Ts to the temperature Tmax is ΔVh.

  In this embodiment, the film pack 160 has a swellable margin that can further accommodate the liquid of ΔVh when the pump chamber 130 is not operating and at the temperature Tmax. Therefore, even when the temperature of the liquid changes to the temperature Tmax, ΔVh, which is an increase in the volume of the liquid, can be absorbed by the film pack 160. ΔVh can be obtained by the following equation (C4). The reason why the temperature is set to “temperature Tmax when the pump chamber 130 is not in operation” is that the amount of liquid stored in the film pack 160 is maximized at this timing. In FIG. 8, when calculating ΔVh, 2.000 cc is adopted as the value of Vs.

B. Second embodiment:
FIG. 10 is a schematic diagram schematically showing a cross-sectional configuration of the fluid circulation device 100b in the second embodiment. The main difference from the first embodiment shown in FIG. 2 is that a suction side buffer 160b is provided instead of the film pack 160, and the other configuration is the same as that of the first embodiment.

  A deformable diaphragm 161 is provided on the upper surface of the suction side buffer 160b. The diaphragm 161 can be deformed according to the amount of liquid stored in the suction side buffer 160b, and the volume of the suction side buffer 160b changes as the diaphragm 161 is deformed.

  In the present embodiment, when the pump chamber 130 operates at the reference temperature Ts, the diaphragm 161 of the suction side buffer 160b is deformed, and among the liquids stored in the suction side buffer 160b, a liquid having a volume of ΔVe + ΔVp circulates. Supplied as part of In other words, when the pump chamber 130 operates at the reference temperature Ts, the diaphragm 161 is deformed, so that the volume of the suction side buffer 160b is reduced by ΔVe + ΔVp.

  Further, when the pump chamber 130 operates at the temperature Tmin, the diaphragm 161 of the suction side buffer 160b is further deformed, and among the liquids stored in the suction side buffer 160b, a liquid having a volume of ΔVe + ΔVp + ΔVt is a part of the circulating liquid. Supplied as In other words, when the pump chamber 130 operates at the temperature Tmin, the diaphragm 161 is deformed, so that the volume of the suction side buffer 160b is reduced by ΔVe + ΔVp + ΔVt.

  That is, the suction side buffer 160b accommodates a liquid having a volume equal to or larger than ΔVe + ΔVp + ΔVt at the reference temperature Ts, and supplies the liquid having a volume of ΔVe + ΔVp + ΔVt as a part of the circulating fluid when the diaphragm 161 is deformed. If it is possible. However, in the present embodiment, the suction side buffer 160b also has a function as a part of the liquid circulation path, and therefore contains more liquid than ΔVe + ΔVp + ΔVt.

  Thus, even if the suction side buffer 160b is provided instead of the film pack 160, the negative pressure on the suction side of the circulation pump 110 can be suppressed and the liquid can be circulated stably as in the first embodiment. Is possible.

C. Third embodiment:
FIG. 11 is a schematic diagram schematically showing a cross-sectional configuration of the fluid circulation device 100c in the third embodiment. The difference from the second embodiment shown in FIG. 10 is that the discharge side buffer 143 is omitted, and the other configuration is the same as that of the second embodiment.

  As described above, even when the discharge side buffer 143 is omitted, the negative pressure on the suction side of the circulation pump 110 can be suppressed and the liquid can be circulated stably as in the second embodiment.

D. Fourth embodiment:
FIG. 12 is a schematic view schematically showing a fluid circulation device 100d in the fourth embodiment. The difference from the first embodiment shown in FIG. 2 is that the film pack 160 is omitted in the circulation pump 110, and the branch channel 210 is provided in the liquid channel 190 instead of the film pack 160. In other respects, the configuration is the same as that of the first embodiment.

  The branch channel 210 is provided at a position in the liquid channel 190 close to the pump suction channel 144. 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. The same liquid as the liquid circulating in the liquid flow path 190 is accommodated in the branch flow path 210. Hereinafter, the liquid accommodated in the liquid flow path 190 and the liquid circulating through the circulation pump 110 are 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 the first liquid Lq1 accommodated in the branch flow path 210 is a part of the circulating liquid when the circulation pump 110 is operated. Supplied as

  The branch flow path 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. The fluid circulation device 100d 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, which is a component of the movable part 216, functions as a sealing material for suppressing leakage and evaporation of the first liquid Lq1 from the branch flow path 210 (similar to a liquid stopper of an aqueous ballpoint pen). principle). The high-viscosity gel fluid 214 is composed of polybutene having an average molecular weight of 630 as a base material, and has viscoelasticity and transparency. As the high-viscosity gel fluid 214, for example, polybutene having an average molecular weight of 300 to 3700, α-olefin, or the like 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 as the high-viscosity gel fluid 214. In the case of using the aqueous high-viscosity gel fluid 214, when the gas permeability of the high-viscosity gel fluid 214 is high or when it is easy to dry, an organic solvent is further added onto the high-viscosity gel fluid 214 as a solvent. Permeation and drying may be suppressed by forming an oily layer.

  The second liquid Lq2 is accommodated in the branch flow path 210 in order to suppress 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.

  When the circulation pump 110 operates in this embodiment, a pressure gradient is generated inside the liquid flow path 190 as described in the first embodiment. Then, the first liquid Lq1 in the branch channel 210 is supplied to the liquid channel 190 due to the pressure difference between the internal pressure of the liquid channel 190 and the atmospheric pressure applied to the branch channel 210. As a result, the internal pressure of the liquid channel 190 can be maintained at atmospheric pressure or higher, and the negative pressure on the suction side of the circulation pump 110 can be suppressed.

  As described above, in this embodiment, the fluid circulation device 100d includes the branch flow path 210 that stores the first liquid Lq1, and therefore, as in the first embodiment, negative pressure on the suction side of the circulation pump 110 is suppressed. In addition, the liquid can be circulated stably.

  Moreover, since the branch flow path 210 includes the movable portion 216, the first liquid Lq1 can be prevented from leaking outside from the branch flow path, and further, the first liquid Lq1 can be prevented from being diffused.

  Furthermore, since the fluid circulation device 100d includes the sensor 230, it is possible to measure the position of the movable portion 216 when the circulation pump 110 is stopped, thereby detecting the decrease in the first liquid Lq1 due to external leakage or the like. Can do. In this case, normal operation of the fluid circulation device 100d can be maintained by replenishing the first liquid Lq1 from the branch flow path 210 before the operation of the circulation pump 110.

E. 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.

E1. Modification 1:
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 devices 100 of the above-described embodiments and modifications can ensure stable circulation efficiency and can be applied to various medical devices. is there. For example, the fluid circulation device 100 may be used to adjust the temperature of a motor unit of a medical drill, an ultrasonic generator of an ultrasonic scaler that removes tartar by ultrasonic waves, or the like. Further, the fluid circulation device 100 is not limited to being used for cooling the heat generating portion, but may be used for 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 a separate heating unit for heating the circulating fluid in the fluid circulation device 100.

E2. Modification 2:
In the above embodiment, a liquid, particularly water, is used as the fluid circulating through the fluid circulation device 100, but various fluids can be used 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.

E3. Modification 3:
In the above embodiment, the film pack 160 and the suction side buffer 160b, which is a casing having the diaphragm 161, are employed as the liquid storage chamber. However, the liquid storage chamber is not limited thereto, and for example, an elastic bag-like rubber pack, bellows, etc. A liquid storage chamber that can be deformed according to the amount of liquid to be stored may be employed. Even if such a liquid storage chamber is employed, the same effect as in the above embodiment can be obtained.

E4. Modification 4:
In the above embodiment, a piezoelectric element is employed as the operating element, but not limited thereto, 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. Further, in the above-described embodiment, the laminated type is adopted 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 adopted.

E5. Modification 5:
In the above embodiment, the reference temperature Ts is set to 20 ° C., and the temperature range in which the fluid circulation device is used is set to 0 ° C. to 100 ° C., but these temperatures are not limited to the environment in which the fluid circulation device is manufactured or actually It can be set as appropriate based on the temperature range in which the fluid circulation device is used. In addition, if the volume Vb of the liquid stored in the film pack 160 when the pump chamber 130 is not operating satisfies the following formula (2) at the reference temperature Ts, the liquid shortage can be sufficiently compensated, It is not necessary to unnecessarily increase the volume of the liquid storage chamber (film pack 160), and the fluid circulation device can be reduced in size.
ΔVe + ΔVp + ΔVt ≦ Vb ≦ (ΔVe + ΔVp + ΔVt) × K (2)
However, K is a positive number of 1 or more. For example, K can be selected from 1.5, 2.0, 2.5, 3.0, and the like.

E6. Modification 6:
In the above-described embodiment, the check valve 148 is employed as the fluid resistance element, but not limited thereto, various fluid resistance elements can be employed. FIG. 13 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 that of 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. Moreover, since the fluid resistance element (B) and the fluid resistance element (C) have no movable part like the check valve 148, durability can be improved.

DESCRIPTION OF SYMBOLS 10 ... Fluid injection system 20 ... Fluid injection apparatus 30 ... Pulsation generation | occurrence | production part 32 ... Fluid chamber 34 ... Piezoelectric actuator 36 ... Fluid injection pipe 38 ... Lower case 39 ... Upper case 40 ... Fluid container 42 ... Supply pump 44 ... Connection tube 46 ... Connection tube 100 ... Fluid circulation device 100b ... Fluid circulation device 100c ... Fluid circulation device 100d ... Fluid circulation device 110 ... Circulation pump 112 ... Piezoelectric element case 114 ... Piezoelectric element 116 ... Reinforcing plate 118 ... Diaphragm 120 ... Ring member 130 ... Pump chamber DESCRIPTION OF SYMBOLS 140 ... Flow path case 140C ... Concave part 142 ... Pump discharge flow path 143 ... Discharge side buffer 144 ... Pump suction flow path 146 ... Liquid chamber 148 ... Check valve 160 ... Film pack 160b ... Suction side buffer 161 ... Diaphragm 162 ... Connection member 162a ... Communication hole 164 Film 166 ... open port member 190 ... liquid flow path 196 ... control unit 210 ... branch flow channel 214 ... high-viscosity gel-like fluid 216 ... movable part 218 ... vent 230 ... sensor Lq1 ... first liquid Lq2 ... second liquid

Claims (6)

A fluid circulation device comprising:
A pump chamber that performs the operation of changing the volume;
An inlet channel which is a fluid inflow path to the pump chamber;
A fluid resistance element that inhibits or inhibits the flow of fluid from the pump chamber to the inlet channel;
An outlet channel that is an outlet of fluid from the pump chamber;
A circulation channel that is a channel through which the fluid circulates from the outlet channel to the inlet channel;
A fluid storage section that stores the fluid of volume Vb when the pump chamber is not operating, and supplies the stored fluid as part of the circulating fluid when the pump chamber is operating;
ΔVe is the amount of increase in the volume of the circulation channel during the operation of the pump chamber,
ΔVp is a decrease in volume of the fluid due to a change in the pressure of the fluid that occurs during operation of the pump chamber,
A predetermined temperature within a temperature range in which the fluid circulation device is used is set as a reference temperature Ts,
Of the temperature range in which the fluid circulation device is used, the temperature at which the volume of the fluid is minimized is defined as a temperature Tmin.
When the amount of decrease in the volume of the fluid when the temperature of the fluid changes from the reference temperature Ts to the temperature Tmin is ΔVt,
The volume Vb is the reference temperature Ts.
Vb ≧ ΔVe + ΔVp + ΔVt
Meet the relationship,
The fluid storage unit includes a fluid storage chamber that stores the fluid used for the supply inside,
The volume of the fluid storage chamber can be changed according to the amount of the fluid stored in the interior.
Fluid circulation device. The fluid circulation device according to claim 1,
Of the temperature range in which the fluid circulation device is used, the temperature at which the volume of the fluid is the largest is the temperature Tmax,
When the amount of increase in the volume of the fluid when the temperature of the fluid changes from the reference temperature Ts to the temperature Tmax is ΔVh,
The fluid storage portion can further store a fluid of ΔVh at the temperature Tmax when the pump chamber is not in operation.
Fluid circulation device. The fluid circulation device according to claim 1 ,
The fluid storage chamber is a pack formed in a bag shape,
Fluid circulation device. The fluid circulation device according to any one of claims 1 to 3 ,
The fluid storage part includes a branch channel branched from the circulation channel,
Fluid circulation device. The fluid circulation device according to claim 4 ,
A sealing material that seals the accommodated fluid and moves according to a pressure difference between the pressure of the fluid and the atmospheric pressure inside the branch channel is disposed inside the branch channel. ing,
Fluid circulation device. The fluid circulation device according to claim 5 ,
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 heat of vaporization of the second liquid is greater than the heat of vaporization of the first liquid.
Fluid circulation device.

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