JP2005069052A - Piezoelectric pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric pump miniaturized and lightened by simplification of a pump structure and capable of accurately sending liquid without pulsation. <P>SOLUTION: A piezoelectric vibrator 1 having piezoelectric elements 3 provided on plural part in a longitudinal direction of a deformable shim material 3 is supported by and stored in a part of a pipe wall part 4 of a pump chamber 10. Progressive wave transmitting from one end to another end in a longitudinal direction of the piezoelectric vibrator 1 is generated by displacement generated by applying drive voltage provided with phase difference to each piezoelectric elements 3. Liquid in the pump chamber 10 is sent while being stirred between the piezoelectric vibrator 1 and the pipe wall part 4 by transmission of the progressive wave. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a piezoelectric pump using a piezoelectric element as a vibrator.

Conventionally, a pump using a piezoelectric element as a drive source can be reduced in size and weight, and has advantages such as low noise and no electromagnetic noise. Therefore, a small pump for feeding a liquid has been developed. An example of a pump using a piezoelectric element as a drive source will be described. A check valve that connects the pump chamber and the flow path, and one that feeds liquid in one direction using the volume change caused by the displacement of the piezoelectric element provided in the pump chamber (see Patent Document 1). An ultrasonic motor that is rotationally driven by the generated vibration is used as a drive source to rotate a moving body provided with a squeezing roller and squeeze the tube with the squeezing roller to feed the liquid (see Patent Document 2). There has been proposed one that deforms a tube by circumscribing a flow path and feeds liquid (see Patent Document 3).
JP 2000-265964 A JP 2001-115972 A JP-A-5-202857

The pump shown in Patent Document 1 is likely to cause variations in the amount of liquid that is delivered when the check valve is opened and closed. In addition, since a check valve is provided in the liquid flow path, variation in flow path resistance is increased, and pulsation is likely to occur in liquid feeding, resulting in a decrease in pump efficiency. Also. An error is likely to occur in the amount of liquid fed until the check valve stops moving, and it becomes difficult to maintain the sealing effect of the check valve with time.
In Patent Document 2, the contact portion between the squeezing roller and the tube is easily worn, and regular maintenance is required. In addition, since the angle range for squeezing the tube by the squeezing roller is determined during one rotation of the moving body, the liquid feeding amount can be changed only by changing the rotational speed of the moving body, so the liquid feeding speed is slow, and the motor It is difficult to change the amount of liquid delivered because the load changes. In addition, since the liquid is fed while the tube is crushed by the squeezing roller, pulsation is likely to occur, and further, it is difficult to select a material in consideration of wear and deformation associated with the aging of the tube. Furthermore, there are many parts and it is difficult to reduce the size of the pump.
Furthermore, the pump of Patent Document 3 is likely to be worn and deformed with the aging of the tube, and it is necessary to provide a laminated electrostrictive element that circumscribes the tube. Therefore, an error in the amount of liquid to be fed easily occurs.

  The object of the present invention is to solve the above-mentioned problems of the prior art, to reduce the size and weight by simplifying the pump structure, to deliver liquid accurately without pulsation, and to easily control the direction and amount of liquid feeding. Another object of the present invention is to provide a piezoelectric pump that can withstand long-term use.

In order to achieve the above object, the present invention comprises the following arrangement.
A piezoelectric vibrator in which a plurality of piezoelectric elements are provided in the longitudinal direction of the deformable base material is supported and accommodated by a part of the tube wall of the pump chamber, and a drive in which a phase difference is provided to each piezoelectric element A traveling wave propagating from one end of the longitudinal direction of the piezoelectric vibrator to the other end is generated by the displacement caused by the application of the voltage, and the liquid in the pump chamber is caused to flow between the piezoelectric vibrator and the tube wall portion by the propagation of the traveling wave. It is characterized in that the liquid is fed while being beaten.
By switching the direction in which the driving voltage is applied to each piezoelectric element, the liquid-feeding direction can be switched by changing the traveling direction of the traveling wave.
It is characterized in that the liquid flow velocity is changed by changing the vibration frequency of each piezoelectric element.
In the piezoelectric vibrator, one side of the substrate in the short direction is fixed to the tube wall, and the cross-sectional shape of the tube wall perpendicular to the liquid feeding direction of the liquid flowing through the pump chamber is a space from the fixed end toward the free end. It is formed in the inclined wall surface which a part expands, It is characterized by the above-mentioned.
Alternatively, the central portion in the short direction of the piezoelectric vibrator is fixed to a fixing member protruding from the tube wall to the pipe side, and there are slits in the short direction in the vicinity of the base material on which the piezoelectric element is provided. It is formed. In this case, a driving voltage is applied to the piezoelectric element on one end in the longitudinal direction of the base material, and a driving voltage is applied to the piezoelectric element on the other end in the longitudinal direction with a phase difference of 90 degrees. It is characterized by forming a continuous traveling wave.

When the above-described piezoelectric pump is used, a piezoelectric vibrator having piezoelectric elements provided at a plurality of locations in the longitudinal direction of the base material is supported and accommodated by a part of the tube wall portion of the pump chamber. A traveling wave propagating from one end to the other end in the longitudinal direction of the piezoelectric vibrator is generated by the displacement caused by the application of the driving voltage provided with a phase difference, and the propagation of the traveling wave causes a propagation wave between the piezoelectric vibrator and the tube wall. Since the liquid in the pump chamber is pumped while being pumped, a drive source can be provided in the liquid flow path, and the pump can be reduced in size and weight. Further, since there is no check valve, liquid flow can be carried out with little flow resistance and without deformation of the pipe line, so that liquid can be fed with high accuracy without pulsation and pump efficiency can be improved. In addition, since the liquid can be fed without reducing (deforming) the flow path like a tube, a piezoelectric pump that can withstand long-term use can be provided.
In addition, the liquid feeding direction is switched by changing the propagation direction of the traveling wave due to the vibration of the piezoelectric vibrator, and the liquid flow velocity can be changed by changing the vibration frequency of the piezoelectric element. It is easy to control the amount of liquid and can perform control with a wide adjustment range.

  Hereinafter, the best embodiment of a piezoelectric pump according to the present invention will be described in detail with reference to the accompanying drawings. In the piezoelectric pump of this embodiment, a piezoelectric vibrator in which a plurality of piezoelectric elements are provided in a longitudinal direction of a deformable base material is supported and accommodated in a part of a tube wall portion of the pump chamber. A traveling wave propagating from one end of the longitudinal direction of the piezoelectric vibrator to the other end is generated by the displacement caused by the application of the driving voltage with a phase difference to the piezoelectric vibrator. The present invention can be widely applied to pumps that feed liquid while pumping liquid in the pump chamber.

  A typical configuration of the piezoelectric vibrator will be described with reference to FIGS. In FIG. 1, a piezoelectric vibrator 1 is provided with a plurality of piezoelectric elements 3 in a longitudinal direction of a deformable base material (shim material) 2. As the shim material 2, for example, a metal plate material such as phosphor bronze or stainless steel, or a resin film material such as CFRP (carbon reinforced plastic) is used. The shim material 2 is used as an electrode for applying a voltage to the piezoelectric element 3 and is used for giving strength as a vibrator. The piezoelectric element 3 may be either a bimorph type provided on both sides of the shim material 2 or a unimorph type provided on one side of the shim material 2. The piezoelectric element 2 can also be formed by sticking with an adhesive, vapor deposition of a piezoelectric material on the shim material 2, thermal spraying, or the like. In this embodiment, the intervals between the piezoelectric elements 3 are uniform, but the intervals are not necessarily uniform, and a uniform traveling wave is formed by providing a phase difference in the drive voltage (applied voltage). May be. Further, the number of piezoelectric elements 3 provided in the longitudinal direction of the shim material 2 can be variously designed regardless of whether it is an even number or an odd number.

  A part of the piezoelectric vibrator 1 is fixed in the liquid flow path. In this embodiment, one side of the short direction (width direction) is fixed to the tube wall portion (fixed portion) 4. It is configured to generate a traveling wave by vibrating the free end 5 of the piezoelectric vibrator 1 by energizing each piezoelectric element 3. Specifically, due to the displacement caused by the application of a driving voltage having a phase difference to each piezoelectric element 3, the longitudinal direction of the piezoelectric vibrator 1 (left end in this embodiment) to the other end (right end in this embodiment). A traveling wave propagating to the inside is generated, and the liquid 7 in the pump chamber is fed between the piezoelectric vibrator 1 and the tube wall portion 4 by the propagation of the traveling wave.

  An example of a traveling wave created by the vibration of the piezoelectric vibrator 1 in the liquid feeding pipe 6 will be described with reference to FIG. 2A to 2D show a state in which traveling waves propagate from the left side to the right side. It is assumed that the piezoelectric vibrator 1 is fixed to the tube wall portion 4 on the back side in the vertical direction in the drawing. A voltage having a phase difference is sequentially applied to the piezoelectric element 3 from the leftmost piezoelectric element 3a to the right piezoelectric element 3b. At this time, the liquid 7 is squeezed between the tube wall portion 4 due to the displacement of the piezoelectric vibrator 1, so that the liquid is fed in the direction of arrow F through the liquid feeding tube 6. FIGS. 3A to 3D show the states of FIGS. 2A to 2D in a three-dimensional manner. 3A to 3D, the free end 5 side of the piezoelectric vibrator 1 is greatly waved to form a traveling wave, which is fed in the direction of arrow F. The operation of shifting from the state shown in FIG. 2D to the state shown in FIG. 2A is repeated, and the liquid is supplied in the direction of arrow F through the liquid supply pipe 6.

  When the liquid feeding direction is opposite to the arrow F direction, a phase difference is provided in the order from FIG. 2D to FIG. 2A, and a driving voltage is applied to each of the piezoelectric elements 3a to 3d. The liquid feeding direction of the liquid 7 can be switched. Moreover, the flow velocity of the liquid 7 can be changed by changing the vibration frequency of each piezoelectric element 3a-3d.

  Next, another configuration of the piezoelectric vibrator will be described with reference to FIGS. In the embodiment described above, one side of the piezoelectric vibrator 1 in the short direction (width direction) is fixed to the tube wall 4. In this embodiment, in FIG. 4, a part of the piezoelectric vibrator 1 in the short side direction (width direction), for example, the central part is sandwiched and fixed by a fixing member 8 protruding from the pipe wall part 4 into the pipe. The fixing member 8 is used as an electrode portion that applies a driving voltage to the piezoelectric element 3. The piezoelectric elements 3 are provided on both sides at both ends in the longitudinal direction of the shim material 2. In the vicinity of the shim material 2 on which the piezoelectric element 3 is provided, slits 9 are formed in the lateral direction (width direction). Therefore, the displacement generated by the application of the driving voltage to the piezoelectric element 3 propagates in the longitudinal direction through the connecting portions 2a provided on both sides of the shim material 2 in the short direction (width direction). That is, in the piezoelectric vibrator 1, a wave in which a mountain of traveling waves continues in the width direction of the shim 2 propagates in the longitudinal direction. As described above, the slit 9 is provided in the shim material 2. If the slit 9 is not provided, the displacement of the piezoelectric element 3 is not propagated in parallel in the longitudinal direction as a traveling wave, and the shim material 2 itself This is to prevent absorption by deformation. Note that the length and number of the slits 9 can be arbitrarily changed. Further, if the shape of the shim material 2 is a strip shape, the slit 9 can be omitted.

  An example of the traveling wave generated by the vibration of the piezoelectric vibrator 1 described above will be described with reference to FIGS. The case where a traveling wave is formed in the longitudinal direction of the shim material 2 (arrow F direction) in FIG. A driving voltage is applied to the piezoelectric element 3 at the left end portion in the longitudinal direction of the shim material 2 to momentarily displace it so as to protrude upward, and the driving voltage is applied to the piezoelectric element 3 at the right end portion in the longitudinal direction with a phase difference of 90 degrees. Is applied and momentarily displaced so as to be convex upward, as shown in FIGS. 5 (b) to 5 (d), the longitudinal direction (the direction of arrow F) via the connecting portions 2 a on both sides of the shim material 2. A traveling wave propagates to With the propagation of the traveling wave, the liquid is fed between the piezoelectric vibrator 1 and the tube wall part 4 in the direction of arrow F while being sprinkled.

  Next, an example of a piezoelectric pump using the above-described piezoelectric vibrator 1 will be described with reference to FIGS. 6 (a) and 6 (b) and FIGS. 7 (a) and 7 (b). FIGS. 6A and 6B are quadruple piezoelectric pumps using the piezoelectric vibrator 1 shown in FIGS. Piping connection portions 11 are provided on both sides of the pump chamber 10, and the piezoelectric vibrator 1 is built in the pump chamber 10. One side of the piezoelectric vibrator 1 in the short side direction (width direction) is sandwiched and fixed by a tube wall part 4 forming the pump chamber 10. An electrode portion 12 for applying a driving voltage to each piezoelectric element 3 is provided from the shim material 2. The sectional shape of the pump chamber 10 is such that an inclined wall surface 13 is formed vertically so that the space portion expands from the fixed end to the free end in the width direction of the piezoelectric vibrator 1 (direction orthogonal to the liquid feeding direction). . This corresponds to the amount of displacement (amplitude) of the traveling wave increasing from the fixed end of the piezoelectric vibrator 1 to the free end. The tube wall is generated by the traveling wave generated by the vibration of the piezoelectric vibrator 1. This is to ensure that the liquid 7 is driven into and out of the part 4 and fed in one direction.

  7A and 7B show a vibration transmission type piezoelectric pump using the piezoelectric vibrator 1 shown in FIGS. Piping connection portions 11 are provided on both sides of the pump chamber 10, and the pump chamber 10 is formed in a rectangular cross section (or may be circular in cross section). In the pump chamber 10, the piezoelectric vibrator 1 is built in with a part fixed at both ends in the longitudinal direction. A central portion of the piezoelectric vibrator 1 in the short direction (width direction) is fixed to a fixing member 8 protruding from the tube wall 4 toward the pipe line. The fixing member 8 is used as an electrode portion for applying a voltage to the piezoelectric element 3. A driving voltage is applied to the piezoelectric element 3 on one end side (left end side) in the longitudinal direction of the shim material 2 and a driving voltage is applied to the piezoelectric element 3 on the other end side (right end side) in the longitudinal direction with a phase difference of 90 degrees. A traveling wave in which mountains are continuous in the width direction of 2 is formed. With this traveling wave, the liquid 7 is driven between the tube wall 4 and fed in one direction.

  The above-described piezoelectric pump is expected to be widely used for cooling electronic devices and supplying insulin, and various liquids such as antifreeze and chemicals are used in addition to water.

It is the top view and front view of a piezoelectric vibrator. FIG. 2 is a state explanatory diagram of a liquid feeding operation by the piezoelectric vibrator of FIG. 1. FIG. 2 is a perspective explanatory view of a vibration operation of the piezoelectric vibrator of FIG. 1. It is the top view and front view of the piezoelectric vibrator which concern on another example. FIG. 5 is a perspective explanatory view of the vibration operation of the piezoelectric vibrator of FIG. 4. It is sectional drawing of the piezoelectric pump using the piezoelectric vibrator of FIG. It is sectional drawing of the piezoelectric pump using the piezoelectric vibrator of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 2 Shim material 2a Connection part 3 Piezoelectric element 4 Tube wall part 5 Free end 6 Liquid supply pipe 7 Liquid 8 Fixing member 9 Slit 10 Pump chamber 11 Pipe connection part 12 Electrode part 13 Inclined wall surface

Claims (6)

  A piezoelectric vibrator in which a plurality of piezoelectric elements are provided in the longitudinal direction of the deformable base material is supported and accommodated by a part of the tube wall of the pump chamber, and a drive in which a phase difference is provided to each piezoelectric element A traveling wave propagating from one end of the longitudinal direction of the piezoelectric vibrator to the other end is generated by the displacement caused by the application of the voltage, and the liquid in the pump chamber is caused to flow between the piezoelectric vibrator and the tube wall portion by the propagation of the traveling wave. A piezoelectric pump characterized in that the liquid is fed while being swirled.   2. The piezoelectric pump according to claim 1, wherein the liquid feeding direction is switched by changing the propagation direction of the traveling wave by switching the direction in which the driving voltage is applied to each piezoelectric element.   2. The piezoelectric pump according to claim 1, wherein the flow velocity of the liquid is changed by changing the vibration frequency of each piezoelectric element.   In the piezoelectric vibrator, one side of the substrate in the short direction is fixed to the tube wall, and the cross-sectional shape of the tube wall perpendicular to the liquid feeding direction of the liquid flowing through the pump chamber is a space from the fixed end toward the free end. 2. The piezoelectric pump according to claim 1, wherein the piezoelectric pump is formed on an inclined wall surface such that the portion expands.   The piezoelectric vibrator is sandwiched and fixed by a fixing member that protrudes from the tube wall to the pipe side at the center in the short direction of the base, and in the vicinity of the piezoelectric elements provided at both ends of the base in the longitudinal direction. 2. The piezoelectric pump according to claim 1, wherein slits are respectively formed in the short direction.   The drive voltage is applied to the piezoelectric element on one end in the longitudinal direction of the substrate and the drive voltage is applied to the piezoelectric element on the other end in the longitudinal direction with a phase difference of 90 degrees, so that the peaks are continuous in the short direction of the piezoelectric vibrator. 6. The piezoelectric pump according to claim 5, wherein a wave is formed.

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