JP4047803B2 - Diaphragm pump - Google Patents

Description

  The present invention relates to a diaphragm pump, and more particularly to its structure.

  For example, in the medical field, there is a demand for a pump for injecting a small amount of medicine. Since the drug needs to be accurately infused in a prescribed amount, the pump is required to have an accurate flow rate. A positive displacement pump has a flow rate accurately determined, and a diaphragm pump belonging to the positive displacement pump has a feature that its structure is simple and suitable for miniaturization. Such a diaphragm pump with a minute flow rate is driven by a driving member including a piezoelectric element.

  FIG. 6 is a diagram showing a schematic configuration of a diaphragm pump 100 for minute flow rate. A processed plate 106 processed into a predetermined shape is bonded to a substrate 104 provided with a recess 102. The processed plate 106 is processed so that the position facing the concave portion 102 of the substrate 104 is thinner than the surroundings, and this portion becomes the diaphragm 108 of the pump. A portion surrounded by the concave portion 102 of the substrate and the diaphragm 108 provided to cover the concave portion 102 becomes the pump chamber 110. A driving member 112 made of a piezoelectric element is joined to the diaphragm 108. By applying a voltage to the piezoelectric element, the driving member 112 is deformed, whereby the diaphragm 108 is deformed, and the volume of the pump chamber 110 is expanded or contracted. As such a micro flow diaphragm pump, for example, Patent Document 1 below describes a micro diaphragm pump for artificial pancreas for injecting insulin.

JP 2002-213365 A

  Since the driving member of the micro diaphragm pump described above is supported by a flexible member (diaphragm) with respect to the substrate which is the casing of the pump, the force due to the deformation of the piezoelectric element is efficiently applied to the diaphragm. I couldn't tell. For this reason, there was a problem that the discharge pressure was low. The force generated by the piezoelectric element increases as its volume increases. However, in order to increase the volume of the piezoelectric element, even if the area of the conventional structure is increased as it is, the diaphragm is increased correspondingly, so that the discharge pressure is not increased. Further, when the piezoelectric element is thickened, the cost of the element increases.

  The present invention provides a diaphragm pump that is advantageous for increasing the discharge pressure.

The diaphragm pump of the present invention includes a casing in which a recess is formed, a diaphragm that covers the opening of the recess and defines a pump chamber together with the casing, and a drive member that drives the diaphragm to expand and contract the pump chamber. . Further, the drive member includes a piezoelectric element, and is fixed to the casing at least at two positions located across the pump chamber in a range where the piezoelectric element exists, and is joined to the vicinity of the center of the diaphragm. Has been.

  The drive member is fixed at the portion of the casing within the range where the piezoelectric element exists, and the piezoelectric element is deformed using this as a fulcrum, and the deformation can be efficiently transmitted to the diaphragm. Therefore, the position where the piezoelectric element is fixed to the substrate is preferably a position that is symmetric with respect to the center of the pump chamber. For example, if it protrudes in two places, it can arrange | position to the said 2 points | pieces on the straight line which passes along the center of a pump chamber.

Place the diaphragm and the pump chamber on both sides of the drive member. Furthermore, it can be set as the structure of 2 steps | paragraphs in series which are arrange | positioned on both front and back surfaces, and sends a handling fluid from one side of a pump chamber to the other.

Hereinafter, the technology that is the basis of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a diaphragm pump 10 according to the basic technology of the present invention . A glass substrate 12 and a silicon processing plate 14 are overlaid. The processed plate 14 is processed on each of an upper surface and a lower surface (hereinafter simply referred to as an upper surface and a lower surface) in the drawing. On the lower surface, a substantially square lower surface concave portion 16 is formed at a substantially central portion so as to be dug down. On the other hand, the upper surface recess 18 is formed in a substantially square groove shape on the upper surface so as to surround the periphery of the central portion. As described above, the substrate 12 is bonded to the lower surface of the processed plate 14, and the substrate 12 has two through passages 20 and 22 communicating with the upper and lower surfaces of the substrate at positions corresponding to the lower surface recesses 16. Yes. A portion surrounded by the lower surface recess 16 and the substrate 12 of the processed plate 14 is a pump chamber 24. Check valves 26 and 28 are connected to the through passages 20 and 22, respectively. The check valve 26 connected to the through passage 20 allows only the flow toward the pump chamber 24, and as a result, the through passage 20 functions as a suction passage for the diaphragm pump 10. On the other hand, the check valve 28 connected to the through passage 22 allows only the flow from the pump chamber 24, and as a result, the through passage 22 functions as a discharge passage of the diaphragm pump 10. Hereinafter, the through passages 20 and 22 are referred to as a suction passage 20 and a discharge passage 22, respectively.

  A thin metal plate 30 is joined to the upper surface of the processed plate 14, and a PZT (lead zirconate titanate) piezoelectric element 32 is joined so as to be stacked thereon. The thin plate 30 is joined to the center portion 34 inside the upper surface recess 18 and the portion around the upper surface recess 18 of the processed plate 14. The piezoelectric element 32 is substantially circular, and its periphery is located outside the periphery of the processed plate 14.

  The diaphragm pump 10 shown in FIG. 1A can be considered to have the configuration shown in FIGS. 1B and 1C if the way of viewing is changed. The substrate 12 and the processed plate 14 constitute a casing and a diaphragm of the diaphragm pump 10. The part enclosed by the dashed-dotted line to which the code | symbols 38 and 40 of FIG.1 (b) were attached | subjected corresponds to a casing and a diaphragm (Hereinafter, these code | symbols are used and it describes as the casing 38 and the diaphragm 40). That is, a portion of the processed plate 14 facing the pump chamber 24 is the diaphragm 40, and a portion of the processed plate 14 outside the diaphragm 40 and the substrate 12 is the casing 38. The pump chamber 24 can also be regarded as a space defined by the diaphragm 40 provided so as to cover the opening of the concave portion of the casing 38. Referring to FIG. 2 when the diaphragm pump 10 of FIG. 1 is viewed from above, the peripheral portion of the central portion 34 of the diaphragm 40 is thinner than the periphery because the concave portions are provided from both the upper surface side and the lower surface side. . Further, the thin plate 30 and the piezoelectric element 32 drive the diaphragm 40, but it is the range where the piezoelectric element 32 exists that actually contributes to the generation of the driving force, and this part, that is, FIG. Hereinafter, a portion surrounded by an alternate long and short dash line indicated by reference numeral 42 is referred to as a drive member 42.

  As shown in FIG. 2, the outer periphery of the drive member 42 is located outside the upper surface recess 18 of the processed plate 14, and the entire outer periphery is directly fixed to the processed plate 14, that is, the casing 38. That is, the outer diameter of the drive member 42 is larger than the diameter of the pump chamber 24, that is, my dimension. Since the pump chamber 24 of the diaphragm pump 10 has a substantially square shape, the maximum dimension is the dimension in the diagonal line, but the outer diameter of the drive member 42 is larger than this dimension.

  FIG. 3 is an explanatory view of the operation of the diaphragm pump 10. When a voltage is applied to the piezoelectric element 32 by a lead wire (not shown), the piezoelectric element 32 expands and contracts according to the polarity. When the piezoelectric element 32 is to be expanded, since the thin plate 30 is bonded to the lower surface, this surface is constrained, so that the driving member 42 is on the upper side, that is, the side opposite to the side on which the thin plate 30 is bonded. It warps so that it may become convex (refer Fig.3 (a)). Conversely, when the piezoelectric element 32 is about to contract, the drive member 42 is warped so as to protrude downward (see FIG. 3B). Due to the movement of the drive member 42, the diaphragm 40 is driven, the volume of the pump chamber 24 is changed, and the diaphragm pump 10 operates. FIG. 3A shows the suction stroke, and FIG. 3B shows the discharge stroke.

  Since the periphery of the drive member 42 is fixed to the casing 38 that is a rigid body, the above-described operation of the drive member 42 is reliably transmitted to the central portion 34 of the diaphragm 40 and pushes and pulls the diaphragm 40. Moreover, the thin part around the central part 34 makes the diaphragm 40 easy to bend, and further, since this part is not in contact with the driving member 42, the deformation of the driving member 42 is not restrained.

As described above, da IA Fulham pump 10, the periphery of the circular piezoelectric elements 32, over the entire circumference, is fixed at the outside of the top recess 18 of the working plate 14, the drive member 42 motion here as a fulcrum To do. In contrast to this, the piezoelectric element can be made smaller as shown by a one-dot chain line indicated by reference numeral 44 in FIG. The piezoelectric element 44 projects outward from the outer periphery of the upper surface recess 18 in four directions, that is, at four locations, and is fixed to the processed plate 14, that is, the casing 38 at these portions. In this case, in the portion where the drive member is fixed to the casing, the outer diameter of the drive member is larger than the size of the pump chamber. As shown, the size of this portion of the pump chamber 24 corresponds to the length of the side of the square. The outer diameter of the driving member is larger than the square side and smaller than the diagonal line. Even in this case, the driving member moves with the fixed portion as a fulcrum, and the force can be effectively transmitted to the diaphragm 40. The portion where the piezoelectric element is fixed to the substrate is preferably arranged symmetrically with respect to the center of the central portion 34. For example, two locations of the piezoelectric element can be provided at a position equidistant from the center on one straight line passing through the center. Further, if there are three places, the circumference can be divided into three equal parts, and if there are four places, it can be a position on two straight lines that intersect at an angle other than a right angle other than the piezoelectric element 44 of FIG.

Figure 4 is a sectional view showing a schematic configuration of a diaphragm pump 50 according to the related art of the basic technology of the present invention. Since the structure of the board | substrate 12 and the processed board 14 is the same as that of the structure of the diaphragm pump 10, the description is abbreviate | omitted. A characteristic configuration of the diaphragm pump 50 is a drive member 52. The drive member 52 includes a thin metal plate 54 and two piezoelectric elements 56 and 58 joined so as to sandwich the metal plate 54. That is, in contrast to the so-called unimorph type of the diaphragm pump 10, in this example , the drive member 52 is configured as a bimorph type. In the drawing, the lead wire for power feeding is omitted, but the voltage is supplied to the two piezoelectric elements 56 and 58 so that when one contracts, the other expands. The relationship between the diameters of the piezoelectric elements 56 and 58 and the upper surface recess 18 of the processed plate 14 is the same as that of the diaphragm pump 10 described above. By using the bimorph type, it is possible to further increase the force for driving the diaphragm than the diaphragm pump 10 described above.

  FIG. 5 is a cross-sectional view showing a schematic configuration of the diaphragm pump 70 of the present embodiment. The diaphragm pump 70 is configured by joining processed plates 14A and 14B and substrates 12A and 12B to both front and back surfaces of a drive member 42 similar to the diaphragm pump 10 described above. The lower pump in the figure is the first pump 72A and the upper pump is the second pump 72B in the drive member 42, and the configuration of each of the pumps 72A and 72B is basically the same as the diaphragm pump 10 described above. Description is omitted. The discharge path 22A of the first pump 72A is connected to the suction path 20B of the second pump 72B. When the drive member 42 is warped downward, the first pump 72A is in the discharge stroke, and the second pump 72B is in the suction step. When the drive member 42 is warped upward, the first pump 72A is in the suction stroke, The two pumps 72B are in the discharge process, and the phases of these two pumps 72A and 72B are reversed. As described above, since the two pumps 72A and 72B are connected to the discharge path 22A and the suction path 20B, the diaphragm pump 70 as a whole discharges the handling fluid sucked from the suction path 20A from the discharge path 22B. The area of the downstream diaphragm 40B is smaller than that of the upstream diaphragm 40A. Due to this area difference, the suction pressure of the second pump 72B can be increased, and the diaphragm pump 70 as a whole can be discharged at a high pressure.

  In the diaphragm pump 70 of FIG. 5, a bimorph type driving member 52 used in the diaphragm pump 50 of FIG. 3 can be used instead of the unimorph type driving member 42. In addition, the two pumps 72A and 72B may be separately sucked and discharged instead of being arranged in series. In this case, the effective areas of the two diaphragms are changed independently according to the application. be able to.

  Further, the drive member 42 has the piezoelectric element 32 attached and bonded to the thin plate 30, but a single piezoelectric element can also be used. A single piezoelectric element has a convex lens-like shape with a thickened central portion when contracted, and a concave lens-like shape when expanded. A diaphragm can be driven using this unevenness. In this case, since unevenness occurs on both the front and back sides of the piezoelectric element, it is preferable to configure pumps on both sides of the drive member as shown in FIG.

It is sectional drawing which shows the outline | summary of the diaphragm pump 10 which concerns on the technique used as the foundation of this invention. 2 is a plan view showing a main part of the diaphragm pump 10. FIG. FIG. 5 is an operation explanatory diagram of the diaphragm pump 10. It is sectional drawing which shows the outline | summary of the diaphragm pump 50 which concerns on another basic technology . It is sectional drawing which shows the outline | summary of the diaphragm pump 70 of embodiment of this invention . It is sectional drawing of the conventional diaphragm pump.

Explanation of symbols

  10, 50, 70 Diaphragm pump, 12 Substrate, 14 Processing plate, 16 Lower surface recess, 18 Upper surface recess, 24 Pump chamber, 30, 54 Thin plate, 32, 56, 58 Piezoelectric element, 38 Casing, 40 Diaphragm, 42, 52 Drive Element.

Claims (3)

First and second casings each having a recess,
A first diaphragm covering the recess of the first casing and defining a first pump chamber together with the first casing;
A second diaphragm covering a recess of the second casing and defining a second pump chamber together with the second casing;
The first and second diaphragms are joined to the front and back, respectively, and a drive member that drives them to expand and contract the first and second pump chambers;
Have
The drive member includes a piezoelectric element, and is fixed to the one casing at at least two positions located across the at least one of the first and second pump chambers in a region including the piezoelectric element, Join this near the center of the 1st and 2nd diaphragms,
Diaphragm pump. 2. The diaphragm pump according to claim 1, wherein the driving member is joined to the one casing around the entire area including the piezoelectric element. The diaphragm pump according to claim 1 or 2, wherein the handling fluid is sent from the first pump chamber to the second pump chamber, and the area of the second diaphragm is smaller than that of the first diaphragm.

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