JP2005113778A - Pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump which is high in durability by reducing the internal stress in a diaphragm of a diaphragm pump working at the high load pressure. <P>SOLUTION: A difference is provided in the shape of a diaphragm peripheral fixing part so as to bend at different points when the diaphragm is pushed from a flat state and when pulled with a laminated piezoelectric element. Fixation of the diaphragm to a laminated piezoelectric element unit is carried out inside the circumference. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pump that moves a working fluid by changing a volume in a pump chamber using a piston or a diaphragm, and more particularly to a small high-power pump.

Conventionally, in a pump provided with a fluid resistance element such as a check valve only in the inlet channel, and the combined inertance value of the inlet channel is smaller than the combined inertance value of the outlet channel, the discharge flow rate corresponding to the high load pressure is reduced. Many high power and reliable pumps have been developed by the inventors of the present invention. (See Patent Document 1)
This utilizes the inertia effect of the fluid due to the large synthetic inertance value of the outlet channel.

JP 2002-322986 A

  In a pump that moves a fluid by changing the volume in the pump chamber using a diaphragm, it is necessary to make the diaphragm highly rigid in order to obtain a high output under a high load pressure. At that time, since the stress at the bent portion of the diaphragm also increases at the same time, there is a problem that the diaphragm is easily damaged by fatigue.

  In particular, in the configuration of Patent Document 1, in order to sufficiently generate the inertial effect of the fluid, it is necessary to make the pump chamber pressure much higher than that of a pump in which a check valve is arranged in a normal outlet channel. is there. At this time, since the diaphragm also needs to be thickened, the internal stress at the bent portion of the diaphragm increases, and the diaphragm is particularly susceptible to fatigue failure.

  Therefore, an object of the present invention is to provide a highly durable pump by reducing the internal stress of the diaphragm of the diaphragm pump that operates at a high load pressure.

  The pump of the present invention has a pump chamber whose volume can be changed by a diaphragm driven by a laminated piezoelectric element, an inlet flow path for flowing the working fluid into the pump chamber, and an outlet for flowing the working fluid from the pump chamber. In a pump including a flow path and a fluid resistance element that opens and closes the inlet flow path, the shapes of the peripheral fixing portions of the diaphragm on the pump chamber side and the laminated piezoelectric element side are different.

  According to the above configuration, the bending position of the diaphragm by the peripheral fixing portion of the diaphragm is different when it is displaced to the pump chamber side and when it is displaced to the stacking piezoelectric element side. Is relaxed and the durability of the diaphragm can be improved.

  According to a second aspect of the present invention, there is provided a pump chamber whose volume can be changed by a diaphragm driven by a laminated piezoelectric element, an inlet channel for flowing the working fluid into the pump chamber, and the working fluid flowing out from the pump chamber. In the pump including the outlet channel to be opened and the fluid resistance element that opens and closes the inlet channel, the diaphragm is fixed to the laminated piezoelectric element unit on the inner side of the outer periphery of the end face of the piezoelectric element unit.

  According to the above configuration, the bending position of the diaphragm at the periphery of the diaphragm differs depending on whether it is displaced to the pump chamber side or to the laminated piezoelectric element side, so that the amount of deformation of the bent portion is reduced and the internal stress is reduced. As a result, the durability of the diaphragm can be improved.

  In the invention of claim 3, the positional relationship between the multilayer piezoelectric element and the diaphragm is fixed so that the internal stress due to bending of the diaphragm is minimized at the vibration center of the multilayer piezoelectric element.

  According to the said structure, in the invention of Claim 1 and 2, since the stress by the deformation | transformation of a diaphragm will be in the state smallest, durability of a diaphragm becomes still higher.

  According to a fourth aspect of the invention, the combined inertance value of the inlet channel is smaller than the combined inertance value of the outlet channel.

  According to the above configuration, in the pump having a high output but a high pressure in the pump chamber, and the combined inertance value of the inlet flow path in which the durability of the diaphragm is a problem is smaller than the combined inertance value of the outlet flow path, Since the durability of the multi-layer piezoelectric element can be improved and the amount of variation of the multilayer piezoelectric element can be increased, a further high-output pump can be realized.

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

  FIG. 1 shows a longitudinal section of a first embodiment of a pump according to the invention. A case bottom plate 34 is firmly fixed to the lower portion of the piezoelectric element case 31 which is a holding member for the multilayer piezoelectric element by welding. An end plate 33 is bonded in advance to the upper surface of the multi-layer piezoelectric element 32 that is a pump drive source to form a multi-layer piezoelectric element unit, and is fixed inside the piezoelectric element case 31. This fixing is performed by bonding the lower surface of the multilayer piezoelectric element 32 and the upper surface of the case bottom plate 34.

  After fixing the multilayer piezoelectric element 32, the upper surface of the piezoelectric element case 31 and the upper surface of the end plate 33 are processed into the same plane by grinding. During this processing, the central value of the driving voltage of the multilayer piezoelectric element during driving is applied to the multilayer piezoelectric element 32. Accordingly, a step is generated on the upper surfaces of the multilayer piezoelectric element 32 and the end plate 33 when no voltage is applied to the multilayer piezoelectric element.

  After grinding, the diaphragm 22 is bonded to both the end plate 33 and the piezoelectric element case 31. The diaphragm 22 is formed of a stainless steel thin plate having a thickness of 20 μm, and a resin film is attached to an upper surface opposite to the lower surface bonded to the end plate 33 and the piezoelectric element case 31. The pump chamber member 21 is attached so that the diaphragm 22 is sandwiched between the piezoelectric element case 31. The shape of the inner peripheral portion of the outer peripheral fixed portion of the diaphragm 22 of the piezoelectric element case 31 and the pump chamber member 21 is slightly larger in the piezoelectric element case 31.

  As for the pump chamber member 21, the pump chamber 21a, the thin tube part 21b, and the exit connection pipe line 21c are formed in the inside. The piezoelectric element case 31 and the pump chamber member 21 are fixed with screws (not shown). The inlet channel member 11 is fitted to the upper portion of the pump chamber member 21 and is fixed by screws (not shown).

  The open upper surface of the inlet channel member 11 is sealed with a pressure fluctuation absorbing plate 12 that is flexible and has high gas barrier properties. The material of the pressure fluctuation absorbing plate 12 is preferably a composite material of a metal thin film and a resin in order to achieve both flexibility and gas barrier properties.

  An inlet conduit (not shown) is connected to the protruding portion of the inlet passage member 11 provided with the inlet passage 11a. Similarly, an outlet conduit (not shown) is connected to the protruding portion of the pump chamber member 21. The inlet pipe and the outlet pipe are constituted by a resin tube having appropriate flexibility.

  Next, the flow path inside the pump of the present invention will be described. The fluid that flows in from an inlet pipe (not shown) flows from the pressure fluctuation absorption chamber 11b into the pump chamber 21a. The flow path from the pressure fluctuation absorption chamber 11b to the pump chamber 21a is gradually reduced to a hole of about φ0.5 mm and communicates with the pump chamber 21a. A reed valve 23 made of a stainless steel thin plate of 15 μm is installed as a check valve at the boundary between the pressure fluctuation absorption chamber 11b and the pump chamber 21a to prevent backflow from the pump chamber 21a to the pressure fluctuation absorption chamber 11b. doing.

  The pump chamber 21a includes a connecting portion where the thin tube portion 21b opens and a flat compressed portion above the diaphragm 22. The fluid discharged from the pump chamber 21a passes through the narrow tube portion 21b and the connection channel 21c and is sent to a connection pipeline (not shown).

  Next, the operation of the pump of the present invention will be described. First, the inertance value L of the flow path is defined. The inertance value L is given by L = ρ × l / S, where S is the cross-sectional area of the flow path, l is the length of the flow path, and ρ is the density of the working fluid. When the differential pressure of the flow path is ΔP and the flow rate flowing through the flow path is Q, the relation of ΔP = L × dQ / dt is derived by modifying the equation of motion of the fluid in the flow path using the inertance value L. It is.

That is, the inertance value L indicates the degree of influence that the unit pressure has on the temporal change in the flow rate. The larger the inertance value L, the smaller the temporal change in the flow rate, and the smaller the inertance value L, the larger the temporal change in the flow rate.
In addition, the combined inertance value for parallel connection of multiple flow paths and serial connection of flow paths of different shapes is combined with the inertance values of individual flow paths in the same way as the parallel connection and series connection of inductances in electrical circuits. To calculate. Specifically, the combined inertance value when a plurality of flow paths are connected in parallel is obtained by combining in the same manner as the parallel connection of inductances in an electric circuit. Further, the combined inertance value in the case where a plurality of channels having different shapes are connected in series is obtained by synthesizing in the same manner as the series connection of inductances in an electric circuit.

  In addition, when there is a pressure fluctuation absorption element such as a flexible part in the flow path, the combined inertance value may be taken into consideration up to the pressure fluctuation absorption element. Therefore, in the pump of the present invention, the combined inertance value of the inlet channel is the combined inertance value from the pressure fluctuation absorbing plate 12 that is the pressure fluctuation absorbing element to the reed valve 23. On the other hand, the combined inertance value of the outlet channel is the sum of the inertance values of the narrow tube portion 21b and the outlet connection pipeline 21c. Since the outlet channel has a longer channel length and a smaller sectional area compared to the inlet channel, the combined inertance value of the outlet channel is much larger than that of the inlet channel.

  FIG. 2 is a longitudinal sectional view of the main part during operation of the pump in the present embodiment. (a) is when the laminated piezoelectric element is stretched, (b) is when the laminated piezoelectric element is centered, and (c) is when the laminated piezoelectric element is contracted.

  When grinding the upper surface of the multilayer piezoelectric element 32 and the multilayer piezoelectric element case 31, the center value of the driving voltage of the multilayer piezoelectric element during driving is applied to the multilayer piezoelectric element 32 and cutting is performed. The diaphragm 22 is in a planar state at the vibration center of the multilayer piezoelectric element (1), and the generation of internal stress due to bending is the smallest.

  When the stacked piezoelectric element 32 expands, the diaphragm 22 is bent upward at the inner periphery of the contact surface of the pump chamber member 22 with the diaphragm as shown in FIG. On the other hand, when the multilayer piezoelectric element 32 contracts, the diaphragm 22 is bent downward at the inner periphery of the contact surface of the pump chamber member 22 with the diaphragm as shown in FIG.

  The piezoelectric element case 31 and the inner peripheral part of the outer peripheral fixing part of the diaphragm 22 of the pump chamber member 21 are slightly larger in the piezoelectric element case 31, so that when the bending position of the diaphragm is displaced toward the pump chamber side And when it is displaced toward the laminated piezoelectric element. Therefore, compared with the case where the shape of the inner peripheral portion of the outer peripheral fixed portion of the diaphragm 22 of the pump chamber member 21 is the same, the bending amount at the same position is ½, the stress value due to bending is small, and the durability of the diaphragm It can improve the performance.

  FIG. 3 shows a longitudinal and vertical cross section of the main part during the operation of the pump in the second embodiment of the pump according to the present invention. As in the first embodiment, (a) is when the multilayer piezoelectric element is expanded, (b) is when the multilayer piezoelectric element is centered, and (c) is when the multilayer piezoelectric element is contracted.

  In the present embodiment, contrary to the first embodiment, the piezoelectric element case 31 is slightly smaller in the shape of the inner peripheral part of the outer peripheral fixing part of the diaphragm 22 of the piezoelectric element case 31 and the pump chamber member 21. The effect of reducing the stress caused by bending of the other portions, operation, and diaphragm is the same as that of the first embodiment.

  In the configuration of the present embodiment, since the minute gap between the pump chamber member 21 and the diaphragm 22 generated in the first embodiment does not occur in FIG. It is possible to improve the durability of the diaphragm without the foreign matter inside being clogged in the minute gap.

  FIG. 4 shows a vertical and vertical cross section of the main part during the operation of the pump in the third embodiment of the pump according to the present invention. As in the first and second embodiments, (a) is when the multilayer piezoelectric element is expanded, (b) is when the multilayer piezoelectric element is centered, and (c) is when the multilayer piezoelectric element is contracted. is there.

  In the present embodiment, the piezoelectric element case 31 is slightly smaller in the shape of the inner peripheral portion of the outer peripheral fixing portion of the diaphragm 22 of the piezoelectric element case 31 and the pump chamber member 21 as in the first embodiment. Further, the ridge portion of the inner peripheral portion of the outer peripheral fixed portion of the diaphragm 22 of the piezoelectric element case 31 and the pump chamber member 21 is subjected to R processing.

  Further, the diaphragm 22 is fixed to the end plate 33 on the inner side of the outer periphery of the upper surface of the end plate 33, which is the end surface of the piezoelectric element unit. Further, the ridge portion of the outer peripheral portion of the end plate 33 is also subjected to R processing.

  In the operation of this embodiment, when the laminated piezoelectric element 32 is expanded, the diaphragm 22 is bent upward at the inner periphery of the contact surface of the pump chamber member 22 with the diaphragm as shown in FIG. On the other hand, when the multilayer piezoelectric element 32 contracts, the diaphragm 22 is bent downward at the inner periphery of the contact surface of the pump chamber member 22 with the diaphragm as shown in FIG.

  The piezoelectric element case 31 and the inner peripheral part of the outer peripheral fixing part of the diaphragm 22 of the pump chamber member 21 are slightly larger in the piezoelectric element case 31, so that when the bending position of the diaphragm is displaced toward the pump chamber side And when it is displaced toward the laminated piezoelectric element. Therefore, compared with the case where the shape of the inner peripheral portion of the outer peripheral fixed portion of the diaphragm 22 of the pump chamber member 21 is the same, the bending amount at the same position is ½, the stress value due to bending is small, and the durability of the diaphragm It can improve the performance.

  Furthermore, in the present embodiment, the diaphragm 22 is fixed inside the outer periphery of the upper surface of the end plate 33, which is the end surface of the piezoelectric element unit. Therefore, the laminated piezoelectric element 32 is also extended on the inner periphery of the diaphragm 22. In the case of 4 (a), the bending position of the diaphragm is the outer peripheral portion of the end plate 33, and in the case of FIG. 4C in which the laminated piezoelectric element 32 is contracted, the bending position of the diaphragm is the end plate 33. Compared to the case where the fixing is performed up to the outermost periphery of the end plate 33, the bending amount at the same position is also halved in the inner peripheral portion, and the stress value due to bending is It is small and can improve the durability of the diaphragm.

  In addition, the fact that the R processing is applied to each ridge portion can alleviate the bending stress and further improve the durability of the diaphragm.

  The present invention can be used in various industries that use small high-power pumps.

It is a longitudinal section of a 1st embodiment of a pump concerning the present invention. It is a longitudinal cross-sectional view of the principal part at the time of operation | movement of 1st Embodiment of the pump concerning this invention. It is a longitudinal cross-sectional view of the principal part at the time of operation | movement of 2nd Embodiment of the pump concerning this invention. It is a longitudinal cross-sectional view of the principal part at the time of operation | movement of 3rd Embodiment of the pump concerning this invention.

Explanation of symbols

11: Inlet channel member 11a: Inlet connection pipe line 11b: Pressure fluctuation absorption chamber 12: Pressure fluctuation absorption plate 21: Pump chamber member 21a: Pump chamber 21b: Narrow pipe part 21c: Outlet connection pipe line 22: Diaphragm 23: Reed valve 31: Piezoelectric element case 32: Multilayer piezoelectric element 33: End plate 34: Case bottom plate 41: Piezoelectric element case 42: Pump chamber member 43: End plate 44: Case bottom plate 45: Holding screw

Claims (4)

  A pump chamber whose volume can be changed by a diaphragm driven by a laminated piezoelectric element, an inlet channel for flowing working fluid into the pump chamber, an outlet channel for flowing working fluid from the pump chamber, and the inlet A pump comprising a fluid resistance element that opens and closes a flow path, wherein the shape of the peripheral fixing portion of the diaphragm on the pump chamber side and the laminated piezoelectric element side is different.   A pump chamber whose volume can be changed by a diaphragm driven by a laminated piezoelectric element, an inlet channel for flowing working fluid into the pump chamber, an outlet channel for flowing working fluid from the pump chamber, and the inlet A pump comprising a fluid resistance element that opens and closes a flow path, wherein the diaphragm is fixed to the laminated piezoelectric element unit inside the outer periphery of the end face of the piezoelectric element unit.   3. The positional relationship between the multilayer piezoelectric element and the diaphragm is fixed so that an internal stress due to bending of the diaphragm is minimized at the vibration center of the multilayer piezoelectric element. Pump. 4. The pump according to claim 1, wherein a combined inertance value of the inlet channel is smaller than a combined inertance value of the outlet channel.

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