JP2013187989A - Ehd fluid transporting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EHD fluid transporting apparatus having a means for removing a foreign matter attached to electrodes of an EHD pump.SOLUTION: An EHD fluid transporting apparatus 11 for transporting an EHD fluid 20 includes: a channel 14 through which the EHD fluid 20 passes; an EHD pump 15 disposed in the channel 14 and having two electrodes 16 and 17; a DC power supply 18 for applying a voltage to the two electrodes 16 and 17; and a polarity reversing device 19 for reversing the polarity of the voltage applied from the DC power supply 18 to the two electrodes 16 and 17.

Description

  The present invention relates to an EHD fluid transport device, and more particularly, to removal of deposits attached to an electrode of an EHD pump.

  The amount of heat generated by a heating element such as a heating element in an inverter or a CPU of a computer tends to increase. Therefore, an element cooler for efficiently cooling these heating elements is required.

  There is a liquid cooling method in which the heat of the heating element is diffused by filling the cooler with liquid and circulating the liquid. The liquid cooling method has an advantage that, as compared with the air cooling method, the refrigerant has a high thermal conductivity and a large specific heat, so that a large amount of heat can be taken from the heating element in a short time and cooled.

  In the liquid cooling system, a pump for circulating the liquid in the apparatus is required. If the pump fails, the liquid is not circulated and the cooling effect cannot be obtained. For this reason, the pump is required to have a simple configuration and high durability.

  One of the pumps used for the liquid cooling system is a micro pump using electrohydrodynamics (EHD). The EHD pump uses a phenomenon in which a fluid flow is generated between electrodes by applying a voltage to the electrodes in the EHD fluid. In a liquid cooling method using an EHD pump, an EHD fluid is used as a refrigerant. By applying a voltage to the electrode of the EHD pump, the EHD fluid flows and circulates in the cooler.

  The EHD pump causes the EHD liquid to flow by applying a voltage between the electrodes. For this reason, the movable parts which give fluidity, such as a piston and a blade | wing, are not required. Therefore, the apparatus configuration is simplified and the apparatus can be reduced in size. In addition, since there is no friction or vibration, the occurrence of failure is small and durability can be improved.

  EHD fluid is a dielectric liquid and has a property of convection under an electric field. Such convection phenomena include iontophoresis in which convection is generated by movement of ion species generated in the liquid by an electric field, or dielectric molecules are polarized by an electric field in a non-uniform electric field, and the direction of the electric field strength is strong or weak. Although the dielectrophoretic phenomenon that moves in the direction is known, the phenomenon that occurs under an electric field and the flow rate that occurs vary depending on the type of EHD fluid.

  In addition, as one type of EHD fluid, there is an electro-conjugate fluid (ECF). Also in the ECF, a jet flow is generated by applying a voltage between the electrodes, and the ECF convects.

  The principle of the EHD pump is shown in FIG. Here, a state in which a jet flow is generated between the electrodes is described. In FIG. 12, reference numeral 101 is an EHD pump device, 102 is a container filled with EHD fluid, 103 and 104 are electrodes, 105 is an EHD fluid in the container 102, and 106 is for applying a voltage to the two electrodes 103 and 104. Represents the DC power supply. In FIG. 12, a positive voltage is applied to the electrode 104 and a negative voltage is applied to the electrode 103.

  By applying a positive voltage to the electrode 104 and a negative voltage to the electrode 103, an EHD fluid jet stream 107 is generated in the direction from the electrode 104 to the electrode 103, that is, in the positive to negative direction of the electrode. This jet flow creates convection in the EHD fluid.

  FIG. 12 shows an example in which the convection of the EHD fluid occurs in the positive to negative direction of the electrode. In many EHD fluids, convection occurs in the positive to negative direction of the electrode. However, in certain EHD fluids, convection occurs in the negative to positive direction of the electrode. In another specific EHD fluid, the flow direction is determined depending on other conditions such as the shape of the electrode, without depending on the polarity direction of the electrode. In the following description, in order to avoid confusion, the description will be made on the assumption that convection occurs in the positive to negative direction of the electrode. However, the present invention is not limited to this, and the direction of flow depends on the shape of the electrode, etc., without depending on the polarity direction of the electrode, or when convection occurs in the negative to positive direction of the electrode. It can also be applied to the case where it is determined.

  In a cooler using an EHD pump, one problem is that foreign substances and bubbles are mixed in the EHD fluid. Since a high voltage is applied to the electrode of the EHD pump, discharge easily occurs when such foreign matter or bubbles reach the vicinity of the electrode. Discharging may cause electrode breakage or EHD fluid alteration, degrading the performance of the EHD pump and reducing cooling efficiency.

  It is difficult to prevent foreign substances and bubbles from entering the EHD fluid. For this reason, a means for capturing foreign matter and bubbles in the EHD fluid has been proposed so that the foreign matter does not approach the electrode of the EHD pump. Patent Document 1 proposes an apparatus that traps foreign matters and bubbles by providing a trap in a flow path.

  FIG. 13 shows an example of a trap for capturing foreign matter in Patent Document 1. The thermal diffusion device 111 includes a passage forming member 112. Inside the passage forming member 112, a flow path for the EHD fluid to flow is formed. In Patent Document 1, ECF, which is a kind of EHD fluid, is used as the liquid flowing in the flow path. An EHD pump is installed in the flow path. The passage forming member 112 has upper and lower protrusions 113 and 114 that are connected to the flow path inside and are attached to four corners. In the space inside the protrusion, an EHD fluid flows as a part of the flow path. The inside of this protrusion becomes a trap, and foreign matter and bubbles are captured.

  The protrusions 113 and 114 are installed at the four corners of the passage forming member 112 and are further attached vertically. For this reason, regardless of the posture of the thermal diffusion device 111 including the passage forming member 112, any trap exists at a position higher and lower than the EHD pump. With such a configuration, foreign matter and bubbles having a specific gravity lower than that of the fluid are captured by a trap at a higher position, and foreign matters having a specific gravity higher than that of a fluid are captured by a trap at a lower position.

JP 2010-123851 A

  As a result of an experiment in which the EHD fluid was circulated through the flow path using the apparatus shown in FIG. 13, foreign matter and bubbles were trapped by the traps of the protrusions 113 and 114. However, it has been found that the flow rate in the flow path decreases with time.

  The reason why the flow rate is reduced is that the foreign matter is charged with electricity or polarized and becomes charged and adheres to the electrode due to Coulomb force. When foreign matter adheres to the electrodes, the shape of the electrodes changes, and the flow rate between the electrodes decreases. Further, the adhered foreign matter grows greatly, so that the flow at the electrode portion is stagnated and the flow rate of the entire apparatus is reduced. Furthermore, there is a possibility that electric discharge may occur between electrodes to which foreign matter is attached or between an electrode to which foreign matter is attached and foreign matter in the fluid.

  For this reason, it is necessary to provide a means for capturing the foreign matter and a means for separating the foreign matter attached to the electrode so that the foreign matter does not adhere to the electrode of the EHD pump.

  An object of the present invention is to provide an EHD fluid transport device having means for separating foreign matter adhering to an electrode of an EHD pump.

  Another object of the present invention is to provide an EHD fluid transport device having means for capturing foreign matter in the EHD fluid.

  According to the present invention, an EHD fluid transport device (11) for transporting an EHD fluid (20) is installed in a flow path (14) through which the EHD fluid (20) flows and in the flow path (14). An EHD pump (15) having two electrodes (16, 17), a DC power source (18) for applying a voltage to the two electrodes (16, 17), and the two electrodes from the DC power source (18). A polarity inversion device (19) for inverting the polarity of the voltage applied to (16, 17).

  With such a configuration, in the EHD fluid transport device, an effect of separating foreign matter adhering to the electrode from the electrode can be obtained.

  In the above invention, the polarity reversing device (19) includes a switch (55, 56) for reversing the polarity of the voltage applied to the two electrodes (16, 17) by the DC power source (18), and the switching The vessel (55, 56) is preferably constituted by a manual switch.

  With such a configuration, it is possible to obtain an effect that the foreign matter adhering to the electrode is peeled off from the electrode by manually operating the polarity reversing device to reverse the polarity of the electrode.

  In the above invention, the polarity reversing device (19) includes a switch (55, 56) and a timer (57) for reversing the polarity of the voltage applied to the two electrodes (16, 17) by the DC power source (18). ) And the switch (55, 56) is configured by an electrically drivable switch, and the timer (57) measures a predetermined time interval and performs the switching at each predetermined time interval. It is preferable to control the DC power supply (18) to reverse the polarity of the voltage applied to the two electrodes (16, 17) by operating the device (55, 56).

  With such a configuration, the polarity reversing device is automatically operated by the timer to reverse the polarity of the electrode, thereby obtaining the effect of separating the foreign matter adhering to the electrode from the electrode.

  Moreover, in the said invention, it is preferable to provide a recessed part (64) or a convex part (65) in the wall of the said flow path (14).

  With such a configuration, an effect that foreign matter is captured in the concave portion or the convex portion of the flow path wall is obtained.

  Moreover, in the said invention, it is preferable to apply the voltage of a positive electrode or a negative electrode to the wall of the said flow path (14).

  With such a configuration, there is an effect that foreign matter is captured at a place where the voltage of the flow path wall is applied.

  In addition, the code | symbol in the bracket | parenthesis of each said means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a figure (transverse section of a channel and an electrode) showing an EHD fluid transportation device by the present invention. It is a figure which shows one example of the thermal diffusion apparatus using an EHD fluid transport apparatus. FIG. 6 is a diagram (part 1) illustrating an example of the arrangement of an EHD pump and the transport of an EHD fluid. FIG. 6 is a diagram (part 2) illustrating an example of the arrangement of the EHD pump and the transport of the EHD fluid. It is a figure (upper section of a channel and an electrode) showing a principle of EHD fluid transportation by an EHD pump. It is a figure (the 1) which shows the shape of the electrode of an EHD pump. FIG. 3 is a diagram (No. 2) illustrating the shape of an electrode of an EHD pump. It is a figure which shows the example of the polarity inversion apparatus by this invention. It is a figure which shows the structure of the flow path by this invention. It is a figure which shows the example of the shape of the flow path by this invention. It is a figure explaining the method of polarity switching of the several EHD pump arrange | positioned along with the flow path by this invention. It is a figure which shows the principle of an EHD pump. It is a figure which shows the EHD fluid transport apparatus provided with the projection part for a foreign material capture | acquisition.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. The technical scope of the present invention is not limited to these embodiments, but covers the invention described in the claims and equivalents thereof. Moreover, it is also possible to implement with the form which added the various change in the range which does not deviate from the meaning of this invention.

  First, with reference to FIGS. 2 to 7, the heat diffusion device using the EHD fluid transport device according to the present invention and the principle of heat diffusion using the EHD pump will be described.

  FIG. 2 is a view showing the appearance of a heat diffusion device 31 in which the EHD fluid transport device according to the present invention is used. The thermal diffusion device 31 includes a cooling unit 32 for cooling the heating element 36, a heat radiating unit 33 for releasing heat sent from the cooling unit 32 via the EHD fluid to the outside, and the cooling unit 32 and the heat radiating unit. It is comprised by the connection part 35 between the parts 33. FIG. The cooling unit 32 and the heat radiating unit 33 each have a flow path forming plate 34. A flow path is formed in the flow path forming plate 34, and the EHD fluid is carried in the flow path. The number of flow path forming plates 34 can be determined by the number of heating elements 36, the amount of heat generation, the device scale, and the like. Two systems of flow paths are formed inside the connecting portion 35, and the EHD liquid is carried between the cooling section 32 and the heat radiating section 33 through the two systems of the connecting section 35.

  In the cooling unit 32, a heating element 36 to be cooled is inserted between the flow path forming plates 34. The heat radiated from the heating element 36 is carried by the EHD fluid flowing through the flow path from the cooling section 32 to the heat radiating section 33 through the flow path of one system of the connecting section 35. Similarly, a flow path is formed in the flow path forming plate 34 of the heat radiating section 33, and the EHD fluid flows in the flow path. The heat of the heating element 36 carried from the cooling unit 32 is released into the air by the air cooling fins 37 installed between the flow path forming plates 34 of the heat radiating unit 33. The cooled EHD fluid is conveyed to the cooling unit 32 through the flow path of the other system of the connecting unit 35. In the heat diffusion device 31, the EHD fluid performs such a circulation operation to cool the heating element 36 adjacent to the flow path forming plate 34 of the cooling unit 32. The DC power source 38 is a power source for operating the EHD pump.

  The heat diffusing device 31 shown in FIG. 2 is one example, and the heat diffusing device 31 may have other configurations as long as it includes the EHD fluid transport device according to the present invention.

  FIG. 3 shows an internal configuration when the flow path forming plate 34 is viewed from the “A” direction of FIG. The flow path forming plate 34 is configured using an external plate 41 that forms the outside and an internal plate 42 that forms a flow path inside the external plate 41. The flow path includes a vertical flow path 43 and a horizontal flow path 44. In the flow paths 43 and 44, an appropriate number of EHD pumps 15 are installed at appropriate positions to form a flow of the EHD fluid 20 in the flow paths. In FIG. 3, the EHD fluid 20 that has flowed in from the outside of the flow path forming plate 34 (connecting portion 35) flows in the left vertical flow path 43 in the upward direction 45, and is divided into a plurality of horizontal flow paths 44. And flows in the lateral direction 47. Furthermore, the flows of the plurality of lateral flow paths 44 merge, and the EHD fluid 20 flows downward in the vertical flow path 43 on the right side 46 to the outside of the flow path forming plate 34 (connecting portion 35). Discharged.

  The configuration of the flow path shown in FIG. 3 is one example. The number of flow paths and the size of the flow paths can be determined by several conditions such as the type of EHD fluid, the material of the flow path forming plate, the amount of heat generated by the heating element, and the ability of the EHD pump. Furthermore, the number and arrangement interval of the EHD pumps installed in the flow path can be set in consideration of these conditions.

  FIG. 4 shows the internal configuration when the flow path forming plate 34 is viewed from the “B” direction of FIG. Two flow path forming plates 34 and a connecting portion 35 are shown. The EHD fluid 20 flows in the direction 49 through the flow path 48 in the connecting portion 35. In the longitudinal flow path 43 of the two flow path forming plates 34, the EHD fluid 20 is carried upward by the EHD pump 15. An appropriate number of EHD pumps 15 can be installed at appropriate locations.

  When FIG. 4 is viewed from the opposite side surface, the EHD fluid 20 flows downward in the longitudinal flow path 43 of the flow path forming plate 34, and the flow path 48 in the connecting portion 35 flows in a direction opposite to the direction 49. Will flow.

  The configuration of the flow path shown in FIG. 4 is one example. Further, the number of channels and the size of the channels can be determined according to some conditions as described above. In the example of FIG. 4, the EHD pump is not disposed in the flow path 48 in the connecting portion 35, but can be disposed.

  FIG. 5 is a diagram showing the principle of EHD fluid transport using an EHD pump. It is assumed that the EHD fluid 20 is filled in the flow path 14. An EHD pump 15 is installed in the flow path 14. The EHD pump 15 includes two electrodes 16 and 17. In FIG. 5, the power supply 51 applies a positive potential to the electrode 16 and a negative potential to the electrode 17. Thereby, a jet flow 52 of EHD fluid is generated between the electrode 16 and the electrode 17.

  In FIG. 5, the electrode 16 has an acute-angled tip, and the electrode 17 has a hollow shape or a gap. In some EHD fluids, the jet flow 52 is generated by adopting such an electrode shape. However, it is not limited to such a shape. By installing a plurality of EHD pumps 15 in the flow path 14, a flow 53 of the EHD fluid 20 having a flow rate that provides a predetermined heat transfer coefficient necessary for cooling is generated in the flow path 14.

  FIG. 6 shows an example of the shape of the electrode 16. In the example of FIG. 5, a positive electrode potential is applied to the electrode 16. 6A to 6C, it is assumed that the right end of each electrode is directed toward the other electrode 17. (A) is a cone shape with one point as a tip. The bottom surface is shown as a rectangle, but is not limited to this. (B) is a triangular column shape in which the tip portion is constituted by one side. (C) is similarly a pentagonal columnar shape.

  FIG. 7 shows an example of the shape of the electrode 17. In the example of FIG. 5, a negative electrode potential is applied to the electrode 17. In FIGS. 7A and 7B, it is assumed that the electrode 16 facing the left direction of each electrode is installed. (A) is a ring-shaped shape. A jet flow is generated from the tip portion of the electrode 16 toward the ring hollow portion of the electrode 17. (B) is the shape which provided the slit in the electrode. Similar to (a), a jet flow is generated from the tip of the electrode 16 toward the slit of the electrode 17. Since the ring-shaped electrode 17 of FIG. 7A is difficult to manufacture, in this embodiment, the slit-shaped electrode 17 of FIG. 7B is used, and the two pillar portions of the slit are 17a, 17b.

  When the above-described heat diffusion device using the EHD pump is used, there is a case where the foreign matter is charged and attached to the electrode of the EHD pump when the foreign matter is mixed in the EHD fluid. In the structure in which the EHD fluid flow path is sealed, it is conceivable that foreign substances are mixed in when the EHD fluid is inserted, and corrosive substances in the flow path flow out to the EHD fluid. Since it is difficult to completely prevent the contamination of foreign substances in the EHD fluid, it is necessary to capture the foreign substances flowing in the EHD fluid and to separate the foreign substances attached to the electrodes from the electrodes. Note that the EHD fluid flow path may have a structure that is released without being sealed, but in that case, dust in the air is mixed, increasing the amount of foreign matter mixed in the EHD fluid. To do.

  FIG. 1 is a diagram showing an EHD fluid transport device 11 using an EHD pump according to the present invention. (A) is side surface sectional drawing which looked at the flow path from the side surface, (b) is front sectional drawing seen from the "A" direction of (a). The EHD fluid transport device 11 includes a flow path 14 through which the EHD fluid 20 flows, an EHD pump 15, a DC power supply 18, and a polarity reversing device 19. In the case where the electrode 17 has a slit shape, when viewed from above perpendicular to the “A” direction in FIG. 1, one electrode 16 and two slit-shaped electrodes 17 a and 17 b are the same as the electrode 16 in FIG. It will look like 17.

  The flow path 14 is formed by the flow path upper surface 12, the flow path lower surface 13, and two flow path walls. However, the shape of the cross section in the direction perpendicular to the flow direction of the flow path 14 can be a square, a circle, or other shapes. Depending on the shape of the channel cross-section, the configuration of the channel wall varies. The EHD pump 15 is mainly composed of one electrode 16 and a pair of electrodes 17a and 17b. A plurality of EHD pumps 15 can be installed in the flow path. The number and installation interval of the EHD pumps 15 can be determined according to various conditions. For example, the type of EHD fluid, the size and length of the flow path, the scale of the entire apparatus, the amount of heat generated by the heating element to be cooled, and the like. Moreover, the wiring for applying a voltage to the electrode 16 and the electrodes 17a and 17b can be provided on the two flow path walls 22, 23 and the flow path lower surface 13, and the metal layer of the wiring is exposed to the flow path. It may be. Note that the wiring may have an appropriate structure and shape depending on the structure of the flow path and the like.

  A DC power supply 18 applies a positive electrode voltage and a negative electrode voltage to one electrode 16 and one set of electrodes 17 a and 17 b of the EHD pump 15. In the following description, one set of electrodes 17 a and 17 b is represented as an electrode 17. If the EHD fluid 20 to be used has a property of causing a flow from the positive electrode toward the negative electrode when a voltage is applied to the electrode, for example, the DC power supply 18 supplies the electrode 16 with the positive electrode potential and the electrode 17. A negative electrode potential is applied to. Thereby, the flow of the EHD fluid 20 from the electrode 16 toward the electrode 17 is generated. In the other EHD pumps 15 as well, by applying a voltage in the same manner, a flow in the same direction is generated, and an overall flow 21 of the EHD fluid 20 is generated in the flow path, and the EHD fluid is flown in the flow path 14. 20 are transported. The polarity of the voltage applied to the two electrodes is constant, and the EHD fluid 20 always flows in one direction 21.

  In the present invention, a polarity inverting device 19 is provided and connected between the DC power supply 18 and the EHD pump 15. The polarity inverting device 19 inverts the polarity of the voltage applied from the DC power source 18 to the electrodes 16 and 17 of each EHD pump 15. When the positive potential is applied to the electrode 16 and the negative potential is applied to the electrode 17 as in the above example, the polarity reversing device 19 causes the electrode 16 to be the negative electrode and the electrode 17 to be the positive electrode only for a short time. Operate. Such processing is performed, for example, every predetermined time, and the polarity is inverted only for a short time. That is, when a negative electrode voltage is applied to the electrode 17, it becomes a positive electrode for a short time and then returns to the negative electrode. By reversing the polarity of the electrode, for example, a foreign material charged positively and adhering to the negative electrode has a repulsive force between the electrode and the polarity of the adhering electrode. For this reason, the foreign matter adhering to the electrode is peeled off from the electrode and released into the EHD fluid 20. The time for reversing the polarity can be set as appropriate, and can be, for example, between a few ms and a few seconds.

  Polarity reversal is performed automatically using a timer or the like or manually. The polarity switching can be performed mechanically or electrically, but is not limited thereto. For example, using a timer, the polarity can be reversed every few hours for several milliseconds. Such polarity reversal in a short time does not reduce the flow of EHD fluid generated by each EHD pump. Alternatively, the user can be prompted to manually reverse the polarity by blinking a lamp, a buzzer sound, or the like using a timer. Furthermore, after prompting the manual polarity reversal, if the reversal is not executed, it may be performed automatically. The interval at which the polarity is reversed and the time during which the polarity is reversed can be set in consideration of the type of EHD fluid, the scale of the apparatus, the contamination state of foreign matter, and the like.

  FIG. 8 shows an example of the polarity inverting device 19. The polarity inverting device 19 includes two switches 55 and 56 and a timer 57. The switch 55 switches whether the electrode 16 is connected to the positive electrode or the negative electrode of the power source 51. The switch 56 switches whether the electrode 17 is connected to the positive electrode or the negative electrode of the power source 51. The switch 55 and the switch 56 are configured so that the electrodes 16 and 17 are connected to different poles of the power source 51, that is, when the electrode 16 is connected to the positive electrode of the power source 51, the electrode 17 is connected to the negative electrode of the power source 51. When connecting and connecting the electrode 16 to the negative electrode of the power source 51, the electrode 17 operates to connect to the positive electrode of the power source 51. FIG. 8 shows a state in which the electrode 16 is connected to the positive electrode of the power source 51 by the switch 55 and the electrode 17 is connected to the negative electrode by the switch 56 (solid line). The dotted line shows another connection state.

  The switches 55 and 56 are configured by electrically driven high voltage switches having a voltage applied between the electrode 16 and the electrode 17, for example, a withstand voltage of 5 kV or more. The switch 55 can be composed of two switches if it is a switch with one input and one output, and one switch if it is a switch with one input and two outputs. The same applies to the switch 56.

  The timer 57 controls the connection state of the switching devices 55 and 56. Normally, the connection state shown by the solid line in FIG. 8, that is, the switching device 55 makes the electrode 16 the positive electrode of the power source 51, and the switching device 56 makes the electrode 17 Is connected to the negative electrode of the power source 51. The timer 57 includes, for example, an oscillation circuit and a counter circuit, measures a predetermined time interval, switches the connection state of the switches 55 and 56 when a predetermined time interval is measured, and passes a predetermined inversion time. Then, the switches 55 and 56 are controlled so as to return to the original connection state again. Specifically, as indicated by the dotted line for a short time, the switch 55 controls the electrode 16 to be connected to the negative electrode of the power source 51, and the switch 56 is connected to the electrode 17 to the positive electrode of the power source 51. Return to the connection status shown in. After a predetermined inversion time has elapsed, the timer 57 resets the counter circuit and restarts measuring a predetermined time interval.

  The polarity inverting device 19 shown in FIG. 8 is one example, and the present invention is not limited to this. For example, the switches 55 and 56 can be electromagnetic switches that mechanically actuate contacts by electrical operation, but any switch that can be electrically driven can be used. . In addition, if a high breakdown voltage transistor using silicon nitride (SiN), gallium nitride (GaN), or the like having a breakdown voltage higher than the voltage applied between the electrode 16 and the electrode 17 is available, such a It is also possible to configure the switching devices 55 and 56 with transistors.

  Furthermore, the switches of the switching devices 55 and 56 can be configured by manually operated switches such as slide switches and toggle switches. In this case, the timer 57 does not control the switches 55 and 56. The timer 57 is connected to a lamp, buzzer, etc. (not shown). When a predetermined time interval is measured, the timer 57 prompts the user to operate the switches and switches 55 and 56 by blinking the lamp, a buzzer sound, and the like. In response to this, the operator operates the switches of the switches 55 and 56 to switch the polarity of the voltage applied to the electrodes 16 and 17 for a short time.

  In the above example, the polarity switching of the electrodes 16 and 17 of the plurality of EHD pumps 15 is simultaneously performed by the switching devices 55 and 56. However, a plurality of sets of switchers 55 and 56 may be provided to enable polarity switching for each of the electrodes 16 and 17 of each EHD pump 15 and to perform polarity switching with a time difference according to the arrangement order of the EHD pumps 15. . In this case, the switching devices 55 and 56 are configured by electrically drivable switches. Specifically, the polarity of the EHD pump 15 is sequentially switched by shifting the arrangement interval of the EHD pump 15 by the time divided by the flow velocity. The foreign matter peeled off from the electrode due to the polarity switching reaches the vicinity of the EHD pump 15 disposed next according to the flow. At this time, the polarity of the next EHD pump 15 is switched. This makes it possible to switch the polarity without lowering the flow rate, and to reduce the adhesion of foreign matter peeled off from the electrode to other electrodes.

  Note that the plurality of EHD pumps 15 arranged side by side along the flow path may be divided into a plurality of groups, and the polarity inversion device may perform polarity switching while shifting the time for each group. The polarities of the EHD pumps 15 belonging to the same group are simultaneously switched. Grouping is performed as appropriate. For example, a plurality of EHD pumps 15 continuous along the flow of the flow path are made into one group, and the polarity switching time is shifted for each group. Referring to FIG. 10A, a plurality of EHD pumps 15 a to 15 i are arranged along the flow path 14, and are divided into three groups A, B, and C. The polarities of the EHD pumps 15a to 15c belonging to the group A are simultaneously switched, the polarities of the EHD pumps 15d to 15f belonging to the group B are simultaneously switched, and the polarities of the EHD pumps 15g to 15i belonging to the group C are simultaneously switched. Thereby, the number of the switchers 55 and 56 can be reduced.

  A plurality of EHD pumps 15 arranged along the flow path are divided into a plurality of groups, and the EHD pumps 15 arranged in the same order along the flow path in each group are grouped into the same group. However, as described above, the polarity may be switched by shifting the time for each group in consideration of the flow velocity. As a result, the above operations are performed in parallel in a plurality of groups. Referring to FIG. 10B, a plurality of EHD pumps 15a to 15i are arranged side by side along the flow path 14, and are divided into three groups A, B, and C. In group A, the EHD pumps are arranged in the order of 15a, 15b, 15c along the flow path, and in group B, the EHD pumps are arranged in the order of 15d, 15e, 15f along the flow path. The EHD pumps are arranged in the order of 15 g, 15 h, and 15 i along the flow path. In each group, the first EHD pumps 15a, 15d, and 15g arranged along the flow path in each group are group 1, and in each group, the second EHD pumps 15b, 15e, and 15h arranged in the flow path are group 2. The third EHD pumps 15c, 15f, and 15i arranged along the flow path in each group are referred to as a group 3. The polarity inversion device performs polarity switching by shifting the time in the order of groups 1, 2, and 3. Thereby, the number of the switchers 55 and 56 can be reduced.

  The foreign matter mixed in the EHD fluid 20 is charged and adheres to the electrode. Foreign matter adhering to the electrode obstructs the flow in the flow path and reduces the flow rate from the EHD pump. Furthermore, there is a possibility that a discharge occurs between the foreign substances, and there is a possibility that the electrode is broken or the EHD fluid is deteriorated. For these reasons, the efficiency of EHD fluid transportation is greatly reduced.

  In the EHD fluid transport device according to the present invention, the polarity of the electrode of the EHD pump is reversed at predetermined time intervals using a polarity reversing device. Due to the polarity reversal of the electrode, the foreign matter adhering to the electrode is peeled off from the electrode by repulsion. As a result, the EHD fluid transport device can be operated efficiently over a long period of time without degrading the performance of the EHD pump.

  It is also necessary for the polarity reversing device 19 to prevent foreign matter peeled off from the electrode or foreign matter in the EHD fluid from adhering to the electrode again.

  In the example shown in FIG. 9, a negative voltage is applied by a power source 63 to one of the channel walls 61 and 62 that form the channel. As described above, since foreign matter tends to be positively charged, it easily adheres to the channel wall 61 to which the negative voltage is applied. As a result, the foreign matter that is separated from the electrode and flows in the EHD fluid is captured by the flow path wall 61. The voltage applied to the flow path wall may be lower than the voltage applied to the EHD pump.

  Depending on the type of EHD fluid or the like, foreign matter can be captured by applying a positive voltage to one of the flow path walls 61 and 62. It is also possible to apply a positive potential to the channel wall 61 and apply a negative potential to the channel wall 62.

  When a voltage is applied to the flow path wall, the voltage can be applied only to a part of the flow path walls. Alternatively, a voltage can be applied to the channel walls of all the channels inside the apparatus. For example, although wiring for applying a voltage to the electrodes 16 and 17 is provided on the flow path wall, electrodes for avoiding these wirings and capturing foreign substances are provided. In addition, wiring for applying a voltage to the electrodes 16 and 17 formed on the flow path wall also functions as an electrode for capturing foreign matter.

  As shown in FIG. 10, the flow path wall 61 can be provided with a concave portion or a convex portion. In FIG. 10A, the channel wall 61 is provided with a concave portion 64, and in FIG. 10B, a convex portion 65 is provided. By providing the projections and depressions, foreign matter is easily captured by these projections and depressions. In FIG. 10, although it was set as the recessed part or the convex part, it is not limited to these. For example, both concave and convex portions may be provided alternately. Alternatively, other shapes can be used. Furthermore, as shown in FIG. 9, a voltage can be applied to the flow path wall provided with the concave portion or the convex portion. This makes it easier for foreign matter to be captured.

  By applying a voltage to the flow path wall or providing a concave or convex portion, foreign matter separated from the electrode of the EHD pump is captured by the flow path wall and is prevented from adhering to the electrode of the EHD pump again. .

DESCRIPTION OF SYMBOLS 11 EHD fluid transport apparatus 12 Channel upper surface 13 Channel lower surface 61, 62 Channel wall 14 Channel 15 EHD pump 16, 17 Electrode 18, 38, 51, 63 DC power supply 19 Polarity inversion device 20 EHD fluid 31 Heat diffusion device 34 Flow path forming plate 36 Heating element 55, 56 Polarity changeover switch 57 Timer

Claims (5)

An EHD fluid transport device (11) for transporting an EHD fluid (20) comprising:
A flow path (14) through which the EHD fluid (20) flows;
An EHD pump (15) installed in the flow path (14) and comprising two electrodes (16, 17);
A DC power supply (18) for applying a voltage to the two electrodes (16, 17);
A polarity inversion device (19) for inverting the polarity of the voltage applied to the two electrodes (16, 17) from the DC power source (18);
An EHD fluid transport device characterized by comprising:   The polarity reversing device (19) includes a switch (55, 56) that reverses the polarity of the voltage applied to the two electrodes (16, 17) by the DC power supply (18), and the switch (55, 56. The EHD fluid transport device of claim 1, wherein 56) comprises a manual switch. The polarity reversing device (19) includes a switch (55, 56) and a timer (57) for reversing the polarity of the voltage applied to the two electrodes (16, 17) by the DC power source (18),
The switch (55, 56) is composed of an electrically drivable switch,
The timer (57) measures a predetermined time interval, operates the switch (55, 56) at each predetermined time interval, and the DC power source (18) causes the two electrodes (16, 17) to operate. 2. The EHD fluid transport device according to claim 1, wherein the EHD fluid transport device is controlled so as to reverse a polarity of a voltage applied to.   The EHD fluid transport device according to any one of claims 1 to 3, wherein the wall of the flow path (14) is provided with a concave portion (64) or a convex portion (65).   5. The EHD fluid transport device according to claim 1, wherein a positive or negative voltage is applied to a wall of the flow path (14).

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