Pumps and beverage dispensers

Abstract

A pump capable of suppressing a decrease in pump efficiency even when a substance to be transported leaks from a pump chamber. [Solution] Pump 1 includes pistons 71, 72, 81, 82 that slide within cylinders 73, 83 to reduce or increase the volume of pump chambers 7, 8 that are provided on flow path 5 through which a fluid to be transported flows, O-rings 76 that are provided on the outer surfaces of pistons 71, 72, 81, 82 and seal gaps with the inner surfaces of cylinders 73, 83, diaphragm seals 77 that are provided outside of pump chambers 7, 8 relative to O-ring 76 and prevent fluid that has leaked from O-ring 76 from further leaking to the outside, and a return flow path 78 that returns fluid that has leaked from O-ring 76 to the flow path 5 upstream of pump chambers 7, 8. One end of return flow path 78 that faces cylinders 73, 83 is open toward pump chambers 7, 8 relative to diaphragm seal 77 in the piston sliding direction.

Description

[Technical Field]

[0001] The present disclosure relates to a pump and a beverage dispensing device. [Background technology]

[0002] Conventionally, pumps equipped with a piston for increasing or decreasing the volume of a pump chamber have been known. In such conventional pumps, an annular sealing member such as an O-ring is provided on the outer circumferential surface of the piston to prevent leakage of the liquid or gas to be transferred from a gap between the piston and the cylinder due to sliding of the piston within the cylinder (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3331489 Summary of the Invention [Problem to be solved by the invention]

[0004] However, even with a seal to prevent leakage, leakage can occur, for example, when the piston slides at high speed. In this case, the greater the amount of liquid or gas leaking from the pump chamber, the lower the pump efficiency. This is particularly noticeable when the pump is used in an espresso machine, which requires high-pressure output.

[0005] The present disclosure aims to provide a pump and a beverage supply device that can suppress a decrease in pump efficiency even when a substance to be transported leaks from a pump chamber. [Means for solving the problem]

[0006] A pump according to one aspect of an embodiment of the present invention comprises a flow path through which an object to be transferred flows, a pump chamber provided on the flow path, a piston that slides within a cylinder to reduce or increase the volume of the pump chamber, a first sealing member provided on the outer surface of the piston and sealing the gap between the piston and the inner surface of the cylinder, a second sealing member provided outside the pump chamber relative to the first sealing member and preventing further leakage of the object to be transferred that has leaked from the first sealing member to the outside, and a return flow path that returns the object to be transferred that has leaked from the first sealing member to the flow path upstream of the pump chamber, one end of the return flow path being open toward the pump chamber relative to the second sealing member in the sliding direction of the piston. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a pump and a beverage supply device that can suppress a decrease in pump efficiency even if a substance to be transported leaks from a pump chamber. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an example of the appearance of a pump according to an embodiment; [Figure 2] Schematic diagram showing the general configuration inside the housing of the pump shown in Figure 1 [Figure 3] FIG. 1 is a perspective view showing a schematic configuration of a resonant actuator; [Figure 4] An exploded perspective view of the resonant actuator shown in Figure 3. [Figure 5] 1 is a schematic diagram of a cross-sectional shape of a pump according to an embodiment taken along a symmetry axis CA; [Figure 6] 10 is a schematic diagram of a cross-sectional shape of a fourth flow path of the pump according to the embodiment, taken along the axial direction; [Figure 7] Schematic diagram showing pump operation when coil is energized [Figure 8] 8 is a schematic diagram showing the first pump chamber and its surroundings in the state shown in FIG. 7; [Figure 9] Schematic diagram showing pump operation when the coil is de-energized [Figure 10]10 is a schematic diagram showing the periphery of the first pump chamber in the state of FIG. [Figure 11] Schematic diagram of the magnetic field generated in an electromagnet using a flat core as a comparative example [Figure 12] Plan view of the internal structure of the pump housing from the Z positive side [Figure 13] 1 is an enlarged schematic view of a pump chamber according to the present embodiment; [Figure 14] Schematic diagram showing the state in which the piston moves in the direction that reduces the volume of the pump chamber [Figure 15] Schematic diagram showing the state in which the piston moves in a direction that increases the volume of the pump chamber. [Figure 16] 1 is a diagram showing an application example of a pump according to an embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0010] In the following description, the X, Y, and Z directions are perpendicular to one another. The X and Y directions are horizontal, and the Z direction is vertical. The X direction is the longitudinal direction of the housing 2 and the resonant actuator 6. The Y direction is the lateral direction of the housing 2 and the resonant actuator 6. For ease of explanation, the positive Z direction may also be referred to as the upper side, and the negative Z direction may also be referred to as the lower side.

[0011] [Basic pump configuration] The basic configuration of a pump 1 according to an embodiment will be described with reference to FIGS.

[0012] 1 is a perspective view showing an example of the appearance of a pump 1 according to an embodiment. As shown in FIG. 1, the pump 1 includes a housing 2, an inlet 3, and an outlet 4.

[0013] The housing 2 houses elements related to the pump function, such as a flow path 5 and a resonant actuator 6, which will be described later. In the example of Fig. 1, the housing 2 has a pair of rectangular main surfaces 21 and 22, and is formed in the shape of a rectangular parallelepiped, with the dimension between the main surfaces 21 and 22 being relatively thin compared to the sides of the main surfaces.

[0014] The pair of principal surfaces 21, 22 are formed to have the same shape and are arranged opposite each other in the Z direction. The pair of principal surfaces 21, 22 are arranged such that the long sides of the rectangle face each other in the Y direction and the short sides face each other in the X direction. That is, the pair of principal surfaces 21, 22 are formed so as to be line-symmetric in the Y direction with respect to an axis of symmetry CA (see FIG. 2) that passes through the center of the short sides in the Y direction and extends in the X direction, and are also formed so as to be line-symmetric in the X direction with respect to an axis of symmetry CB (see FIG. 2) that passes through the center of the long sides in the X direction and extends in the Y direction. FIG. 1 shows a center line CO of the pump 1 that passes through the intersection of these two axes of symmetry CA, CB (i.e., the center of the pair of principal surfaces 21, 22) and extends in the Z direction.

[0015] Four side surfaces 23 to 26 are provided between the pair of principal surfaces 21, 22, connecting the four sides of each principal surface. One pair of the four side surfaces 23, 24 is formed in the same rectangular shape and arranged opposite each other in the X direction, with the long sides of each side surface connected to the short sides of the pair of principal surfaces 21, 22. The other pair of the four side surfaces 25, 26 is formed in the same rectangular shape and arranged opposite each other in the Y direction, with the long sides of each side surface connected to the long sides of the pair of principal surfaces 21, 22.

[0016] Inlet port 3 draws fluid into housing 2. Outlet port 4 discharges fluid pressurized by the pump function inside housing 2. In the example of FIG. 1 , inlet port 3 is provided on the Y-negative side of side surface 23 of housing 2, and outlet port 4 is provided on the Y-positive side of side surface 24. Inlet port 3 and outlet port 4 are both connected in the X direction and are arranged so that the direction of fluid intake from inlet port 3 into housing 2 and the direction of fluid discharge from housing 2 to outlet port 4 are the same. In addition, inlet port 3 and outlet port 4 are arranged so that they are point-symmetrical when viewed from the Z direction with respect to the center line CO of pump 1.

[0017] FIG. 2 is a schematic diagram showing the general configuration inside the housing 2 of the pump 1 shown in FIG. 1. FIG. 2 is a plan view of the pump 1 as viewed from the positive Z direction. FIG. 2 schematically shows the internal structure of the housing 2, and the outer shape of the housing 2 (i.e., the four side surfaces 23-26) is shown by a two-dot chain line. FIG. 2 also shows by a dash-dot chain line an axis of symmetry CA that passes through the center in the Y direction of the main surfaces 21 and 22 of the housing 2 and extends in the X direction, and an axis of symmetry CB that passes through the center in the X direction and extends in the Y direction. In FIG. 2, the intersection of the axis of symmetry CA and the axis of symmetry CB is shown as a center line CO.

[0018] 2, the pump 1 is provided with a flow path 5 inside the housing 2, which connects the intake port 3 and the exhaust port 4. The flow path 5 has a first flow path 51, a second flow path 52, a third flow path 53, a fourth flow path 54, a fifth flow path 55, a sixth flow path 56, a seventh flow path 57, and an eighth flow path 58.

[0019] The first flow path 51 has its upstream end connected to the downstream end of the intake port 3 and is arranged to extend in the X-positive direction. The second flow path 52 and the third flow path 53 have their upstream ends both connected to the downstream end of the first flow path 51, branch off, and are arranged to extend in the X-negative direction and the X-positive direction, respectively. The fourth flow path 54 has its upstream end connected to the downstream end of the second flow path 52 and is arranged to extend in the Y-positive direction. The fifth flow path 55 has its upstream end connected to the downstream end of the third flow path 53 and is arranged to extend in the Y-positive direction. The sixth flow path 56 has its upstream end connected to the downstream end of the fourth flow path 54 and is arranged to extend in the X-positive direction, and the seventh flow path 57 has its upstream end connected to the downstream end of the fifth flow path 55 and is arranged to extend in the X-negative direction, and the sixth flow path 56 and the seventh flow path 57 are arranged to merge at their downstream ends. The eighth flow path 58 has its upstream end connected to the junction of the sixth flow path 56 and the seventh flow path 57, extends in the X positive direction, and is disposed so that its downstream end is connected to the upstream end of the outlet 4. Note that in Figure 2, the flow direction of the fluid flowing inside the intake port 3, the flow path 5, and the outlet 4 is shown by arrows.

[0020] 1, the inlet 3 and the outlet 4 are arranged so as to be point-symmetrical when viewed from the Z direction with respect to the center line CO of the pump 1. Therefore, it is preferable that the overall shape of the flow path 5 is also arranged so as to be point-symmetrical when viewed from the Z direction with respect to the center line CO of the pump 1. This makes it easier for the fluid to flow from the inlet 3 to the outlet 4 through the flow path 5.

[0021] Also, a resonant actuator 6 is installed inside the housing 2 as a drive source for the pump 1. The resonant actuator 6 has an electromagnet 61 and is a device that generates vibration motion by switching the electromagnet 61 between energized and de-energized states. The resonant actuator 6 also puts the movable part, which is a vibration element (a group of components including movable plates 62 and 63 and leaf springs 64 and 65, described below), into a resonant state by setting the frequency of the control signal that switches between energized and de-energized states (i.e., switching frequency) to the same frequency as or close to the resonant frequency of the movable part. As a result, the resonant actuator 6 can efficiently vibrate the movable part by utilizing the resonance of the movable part in addition to the attraction of the movable part by the electromagnet 61 when the electromagnet 61 is energized.

[0022] 2, the resonant actuator 6 is arranged so that the X direction is the longitudinal direction and the Y direction is the lateral direction, and is arranged at the center when viewed in the Z direction. Similar to the housing 2, the resonant actuator 6 is also formed so as to be line-symmetric in the Y direction with respect to the axis of symmetry CA, and so as to be line-symmetric in the X direction with respect to the axis of symmetry CB. The electromagnet 61 is arranged at the center of the resonant actuator 6.

[0023] Furthermore, the fourth flow path 54 of the flow path 5 is disposed adjacent to the electromagnet 61 on the negative X side, and is disposed so as to penetrate the resonant actuator 6 in the Y direction. Similarly, the fifth flow path 55 of the flow path 5 is disposed adjacent to the electromagnet 61 on the positive X side, and is disposed so as to penetrate the resonant actuator 6 in the Y direction.

[0024] Furthermore, a first pump chamber 7 and a second pump chamber 8 are provided in the fourth flow path 54 and the fifth flow path 55, respectively, at portions that overlap with the resonant actuator 6 as viewed in the Z direction. The first pump chamber 7 and the second pump chamber 8 are elements that pressurize and send fluid from the upstream side to the downstream side of the flow path 5 in response to the vibration motion of the resonant actuator 6. The fluid in the flow path 5 can flow from the intake port 3 to the exhaust port 4 by the operation of the first pump chamber 7 and the second pump chamber 8. In the example of FIG. 2, both the first pump chamber 7 and the second pump chamber 8 are arranged on the axis of symmetry CA of the housing 2 and the resonant actuator 6. As described above, in the example of FIG. 2, the shape of the flow path 5 is arranged to be point-symmetric as viewed in the Z direction with respect to the central axis CO that passes through the centers of the pair of main surfaces 21, 22 of the housing 2. As a result, the first pump chamber 7 and the second pump chamber 8 are each positioned at approximately the middle position on the flow path 5, so that the energy required to draw fluid into the first pump chamber 7 and the second pump chamber 8 and to discharge fluid from the first pump chamber 7 and the second pump chamber 8 can be made approximately the same.

[0025] The configuration of the resonant actuator 6 of the pump 1 according to this embodiment will be described with reference to Figures 3 and 4. Figure 3 is a perspective view showing a schematic configuration of the resonant actuator 6. Figure 4 is an exploded perspective view of the resonant actuator 6 shown in Figure 3. The perspective directions of Figures 3 and 4 are the same as those of Figure 1.

[0026] As shown in FIGS. 3 and 4, the resonant actuator 6 includes an electromagnet 61, a pair of movable plates 62 and 63, and a pair of leaf springs 64 and 65.

[0027] The electromagnet 61 is disposed at the center of the resonant actuator 6 in the Z direction. As shown in FIG. 4, the electromagnet 61 has a core 611 and a coil 612. The core 611 has a winding portion 611A and a pair of widened portions 611B. The winding portion 611A is located at the center of the core 611 in the X direction and is formed to extend in the X direction. The winding portion 611A has a rectangular cross section along the YZ plane, and has four outer circumferential surfaces with the Y positive side, Y negative side, Z positive side, and Z negative side as normal directions. A coil 612 is wound around the outer circumferential surface of the winding portion 611A. The pair of widened portions 611B are formed at both ends of the winding portion 611A in the X direction, protruding on both sides in the Z direction relative to the winding portion. Widened portion 611B also has a rectangular cross section along the YZ plane, and has four faces whose normal directions are the positive Y, negative Y, positive Z, and negative Z. That is, widened portion 611B has upper and lower end faces that protrude by the same amount from wound portion 611A along the Y direction.

[0028] When a current flows through the conductor that forms the coil 612, the electromagnet 61 generates a magnetic field that passes through the center of the coil 612. The magnetic field generated by the coil 612 is further strengthened by the core 611.

[0029] The pair of movable plates 62, 63 are plate-like members made of a magnetic material, and include a first movable plate 62 and a second movable plate 63. The first movable plate 62 is disposed on the positive Z side of the electromagnet 61, and the second movable plate 63 is disposed on the negative Z side of the electromagnet 61. The first movable plate 62 and the second movable plate 63 are formed in the same shape and are disposed opposite each other in the Z direction.

[0030] Since the first movable plate 62 and the second movable plate 63 are made of magnetic material, they are attracted to the electromagnet 61 by the magnetic field generated by energizing the electromagnet 61. Furthermore, when the electromagnet 61 changes from an energized state to a de-energized state, the first movable plate 62 and the second movable plate 63 move in the direction opposite to the attracting action due to the biasing forces applied by the leaf springs 64 and 65 attached to them, respectively. In other words, the first movable plate 62 and the second movable plate 63 can perform an oscillating motion in the Z direction by switching between energizing and de-energizing the electromagnet 61.

[0031] As shown in FIG. 4 , the first movable plate 62 has a central portion 621 and a pair of end portions 622, 623. The central portion 621 is a central portion of the first movable plate 62 in the X direction, and is formed into a rectangular shape with its long sides facing each other in the Y direction and its short sides facing each other in the X direction when viewed in the Z direction. The central portion 621 is shaped to cover the entire outer shape of the electromagnet 61 when viewed from the Z positive side. The pair of end portions 622, 623 are provided by connecting to both ends of the central portion 621 in the X direction, i.e., the short sides of the rectangular shape. In the example of FIG. 4 , one end portion 622 is located on the negative X direction side of the central portion 621, and the other end portion 623 is located on the positive X direction side of the central portion 621. The Y direction dimension of the pair of end portions 622, 623 is the same as that of the central portion 621. The X direction dimension of the pair of end portions 622, 623 is approximately the same. Furthermore, the thickness dimension in the Z direction of the pair of end portions 622, 623 is preferably formed to be thinner than that of the central portion 621, as exemplified in, for example, FIGS.

[0032] Pistons 71 and 81 are provided on the negative Z direction surfaces of the pair of end portions 622 and 623 of the first movable plate 62 so as to extend in the negative Z direction. The pistons 71 and 81 will be described later.

[0033] The second movable plate 63 has a central portion 631 and a pair of end portions 632, 633. The central portion 631 is a central portion of the second movable plate 63 in the X direction, and is formed into a rectangular shape with its long sides facing each other in the Y direction and its short sides facing each other in the X direction when viewed in the Z direction. The shape of the central portion 631 is formed to cover the entire outer shape of the electromagnet 61 when viewed from the negative Z direction side. The pair of end portions 632, 633 are provided by connecting to both ends of the central portion 631 in the X direction, i.e., the short sides of the rectangular shape. In the example of FIG. 4 , one end portion 632 is located on the negative X direction side of the central portion 631, and the other end portion 633 is located on the positive X direction side of the central portion 631. The Y direction dimension of the pair of end portions 632, 633 is the same as that of the central portion 631. The X direction dimension of the pair of end portions 632, 633 is approximately the same. Furthermore, the thickness dimension in the Z direction of the pair of end portions 632, 633 is preferably formed to be thinner than that of the central portion 631, as exemplified in, for example, FIGS.

[0034] Pistons 72 and 82 are provided on the Z positive side surfaces of the pair of end portions 632 and 633 of the second movable plate 63 so as to extend in the Z positive direction. Pistons 72 and 82 will be described later.

[0035] The pair of leaf springs 64, 65 are elastic members that bias in the Z direction, and include a first leaf spring 64 and a second leaf spring 65. The first leaf spring 64 is disposed on the Z positive side of the first movable plate 62, and the first movable plate 62 is attached to the first leaf spring 64. The second leaf spring 65 is disposed on the Z negative side of the second movable plate 63, and the second movable plate 63 is attached to the first leaf spring 64. The first leaf spring 64 and the second leaf spring 65 have the same shape and are disposed opposite each other in the Z direction. That is, as shown in FIG. 3 , the first leaf spring 64 and the second leaf spring 65 form the outermost parts of the resonant actuator 6 in the Z direction. In response to the attraction of the first movable plate 62 to the electromagnet 61, the first leaf spring 64 biases the first movable plate 62 in the direction opposite to the attraction (Z positive direction). Similarly, in response to the attraction of the second movable plate 63 to the electromagnet 61, the second leaf spring 65 biases the second movable plate 63 in the direction opposite to the attraction (negative Z direction).

[0036] 4, the first leaf spring 64 has a central portion 641, a pair of fixed end portions 642, and a pair of flexible portions 643. The central portion 641 is the center portion of the first leaf spring 64 in the X direction, and is a flat portion having a constant width in the Y direction and outer edges on both sides in the Y direction extending along the X direction. The first movable plate 62 is attached to the central portion 641 of the first leaf spring 64, and thus the first movable plate 62 and the first leaf spring 64 are installed so as to be movable integrally therewith.

[0037] The pair of fixed ends 642 are arranged at both ends of the first leaf spring 64 in the X direction, and are flat plate-like portions formed so that the outer edges in the X direction both extend in the Y direction. The pair of fixed ends 642 of the first leaf spring 64 are fixed to a support 9 (see FIG. 5, etc.) which is an example of a fixed object installed inside the housing 2, thereby fixing both end portions in the X direction.

[0038] The pair of flexible portions 643 are portions that are disposed between a central portion 641 and a pair of fixed end portions 642 along the X direction of the first leaf spring 64. The pair of flexible portions 643 are elastically deformed and bent so as to vary the relative positional relationship in the Z direction between the central portion 641, to which the first movable plate 62 is attached, and the pair of fixed end portions 642 that are fixed to the support body 9. The first leaf spring 64 can bias the first movable plate 62 attached to the central portion 641 by such elastic deformation of the pair of flexible portions 643.

[0039] 4 and other figures, the pair of flexible portions 643 are formed so that the width dimension perpendicular to the direction connecting the central portion 641 and the pair of fixed end portions 642 is relatively small so as to facilitate elastic deformation, and are curved in an S-shape when viewed in the Z direction. In order to make the amount of bending in the Y direction more uniform, the S-shaped curved portions are arranged on both sides of the axis of symmetry CA in the Y direction and are formed so as to be line-symmetrical with respect to the axis of symmetry CA. Note that the curved portions may have a shape other than an S-shape.

[0040] 4, the second leaf spring 65 has a central portion 651, a pair of fixed end portions 652, and a pair of flexible portions 653. The central portion 651 is the center portion of the second leaf spring 65 in the X direction, and is a flat portion having a constant width in the Y direction and outer edges on both sides in the Y direction extending along the X direction. The second movable plate 63 is attached to the central portion 651 of the second leaf spring 65, and thus the second movable plate 63 and the second movable plate 63 are installed so as to be movable together.

[0041] The pair of fixed ends 652 are arranged at both ends of the second leaf spring 65 in the X direction, and are flat plate-like portions formed so that the outer edges in the X direction both extend in the Y direction. The pair of fixed ends 652 of the second leaf spring 65 are fixed to a support 9 (see FIG. 5, etc.) which is an example of a fixed object installed inside the housing 2, thereby fixing both end portions in the X direction.

[0042] The pair of flexible portions 653 are portions that are disposed between a central portion 651 and a pair of fixed end portions 652 along the X direction of the second leaf spring 65. The pair of flexible portions 653 are elastically deformed and bent so as to vary the relative positional relationship in the Z direction between the central portion 651, to which the second movable plate 63 is attached, and the pair of fixed end portions 652 that are fixed to the support body 9. The second leaf spring 65 can bias the second movable plate 63 attached to the central portion 651 by such elastic deformation of the pair of flexible portions 653.

[0043] 4 and other figures, the pair of flexible portions 653 are formed so that the width dimension perpendicular to the direction connecting the central portion 651 and the pair of fixed end portions 652 is relatively small so as to facilitate elastic deformation, and are curved in an S-shape when viewed in the Z direction. In order to make the amount of bending in the Y direction more uniform, the S-shaped curved portions are arranged on both sides of the axis of symmetry CA in the Y direction and are formed so as to be line-symmetrical with respect to the axis of symmetry CA. Note that the curved portions may have a shape other than an S-shape.

[0044] 4, each element of the resonant actuator 6 is arranged so that the center position of each outer shape when viewed in the Z direction coincides with the center line CO of the pump 1. This allows the center of gravity of the resonant actuator 6 to be located near the center line CO of the pump 1, allowing the resonant actuator 6 to operate in a well-balanced manner.

[0045] In this embodiment, the first and second leaf springs 64 and 65 are respectively configured such that the first and second movable plates 62 and 63 are attached at the central portions 641 and 651, but the first and second movable plates 62 and 63 may be attached at any position other than the central portions in the X direction of the first and second leaf springs 64 and 65. Furthermore, the first and second leaf springs 64 and 65 are respectively configured such that they are fixed to the support 9 at a pair of fixed ends 642 and 652, but they may be fixed to the support 9 at any position other than both ends in the X direction.

[0046] Furthermore, in this embodiment, as described above, the first movable plate 62 and the second movable plate 63 are formed to have the same shape, and the first leaf spring 64 and the second leaf spring 65 are formed to have the same shape. The attachment position of the first movable plate 62 to the first leaf spring 64 is also the same as the attachment position of the second movable plate 63 to the second leaf spring 65. Therefore, the resonant frequency of the first movable part (the first movable plate 62 and the first leaf spring 64) is also the same as the resonant frequency of the second movable part (the second movable plate 63 and the second leaf spring 65). Therefore, if the switching frequency of the single electromagnet 61 disposed between the first movable part and the second movable part, which switches between a conductive state and a non-conductive state, is set to the same frequency as or close to the resonant frequency common to the first movable part and the second movable part, both the first movable part and the second movable part can be brought into a resonant state together. This allows the resonant actuator 6 of this embodiment to vibrate the movable part more efficiently.

[0047] The configuration of the first pump chamber 7 and the second pump chamber 8 of the pump 1 according to this embodiment will be described with reference to Figures 5 and 6. Figure 5 is a schematic diagram of the cross-sectional shape of the pump 1 according to this embodiment taken along the axis of symmetry CA. In Figure 5, elements of the pump 1 that are outside the resonant actuator 6, including the housing 2, are not shown.

[0048] As shown in FIG. 5 , the fourth flow path 54 and the fifth flow path 55 are holes formed in a support 9, which is an example of a fixed object installed inside the housing 2. The support 9 may be, for example, a block-shaped component fixed to the inner wall surface of the housing 2. The other flow paths of the flow path 5, other than the fourth flow path 54 and the fifth flow path 55, are also holes formed in the support 9. In the example of FIG. 5 , the support 9 on which the flow path 5 is provided and the support 9 to which the pair of fixed ends 642 of the first leaf spring 64 and the pair of fixed ends 652 of the second leaf spring 65 of the resonant actuator 6 are fixed are illustrated as an integrated component. However, separate components may be integrally connected to each other. Similarly, the first to eighth flow paths 51 to 58 constituting the flow path 5 may be provided in separate supports, and these supports may be connected to form the flow path 5.

[0049] 5 is a cross section taken along the axis of symmetry CA of the pump 1, and therefore, as is clear from reference to FIG. 2, it is a cross section of a portion of the fourth flow path 54 where the first pump chamber 7 is disposed, and a portion of the fifth flow path 55 where the second pump chamber 8 is disposed. As shown in FIG. 5, the first pump chamber 7 and the second pump chamber 8 are provided with cylinders 73 and 83, respectively, which communicate with each other along the Z direction.

[0050] The cylinder 73 of the first pump chamber 7 is formed to open on the Z positive side and the Z negative side of the support body 9. Furthermore, in this embodiment, the first piston 71 provided in the first movable plate 62 and the second piston 72 provided in the second movable plate 63 are disposed in positions where their axial directions overlap with the first pump chamber 7, i.e., positions where they overlap with the axial direction of the cylinder 73. For this reason, as shown in FIG. 5 , the first piston 71 is slidably inserted into the cylinder 73 from the opening on the Z positive side, and the second piston 72 is slidably inserted into the cylinder 73 from the opening on the Z negative side.

[0051] The cylinder 83 of the second pump chamber 8 is formed to open on the Z positive side and the Z negative side of the support body 9. Furthermore, in this embodiment, the first piston 81 provided in the first movable plate 62 and the second piston 82 provided in the second movable plate 63 are disposed at positions where their axial directions overlap with the second pump chamber 8, i.e., positions where they overlap with the axial direction of the cylinder 83. For this reason, as shown in FIG. 5 , the first piston 81 is slidably inserted into the cylinder 83 from the opening on the Z positive side, and the second piston 82 is slidably inserted into the cylinder 83 from the opening on the Z negative side.

[0052] These first pistons 71, 81 and second pistons 72, 82 are respectively mounted on the first movable plate 62 and the second movable plate 63. Therefore, in conjunction with the vibration motion of the first movable plate 62 and the second movable plate 63 in the Z direction caused by energization control of the electromagnet 61, the first pistons 71, 81 and the second pistons 72, 82 slide within the respective cylinders 73, 83, repeatedly moving toward and away from each other. This allows the volumes of the first pump chamber 7 and the second pump chamber 8 to increase or decrease.

[0053] FIG. 6 is a schematic diagram of a cross-sectional shape of the fourth flow path 54 of the pump 1 according to the embodiment, taken along the axial direction. As shown in FIG. 6 , an inlet valve 74 and a discharge valve 75 are provided in the fourth flow path 54, respectively, on the upstream and downstream sides of the first pump chamber 7. When the first piston 71 and the second piston 72 approach each other in the cylinder 73 and the volume of the first pump chamber 7 decreases, the inlet valve 74 closes to prevent fluid from flowing into the first pump chamber 7 from the upstream side of the fourth flow path 54, and the discharge valve 75 opens to discharge fluid from the first pump chamber 7 to the downstream side of the fourth flow path 54. On the other hand, when the first piston 71 and the second piston 72 move away from each other in the cylinder 73 and the volume of the first pump chamber 7 increases, the inlet valve 74 opens to allow fluid to flow into the first pump chamber 7 from the upstream side of the fourth flow path 54, and the discharge valve 75 closes to prevent fluid from being discharged from the first pump chamber 7 to the downstream side of the fourth flow path 54.

[0054] 6 illustrates a configuration for achieving this effect in which both suction valve 74 and discharge valve 75 have a sphere disposed upstream of fourth flow path 54 so as to be able to seal the flow path, and a spring disposed downstream for biasing this sphere upstream. However, the configurations of suction valve 74 and discharge valve 75 other than those shown in FIG. 6 may also be used.

[0055] In this embodiment, the volume of the first pump chamber 7 is the area between the lower end surface of the first piston 71 and the upper end surface of the second piston 72 in the cylinder 73. This volume increases or decreases in accordance with the up and down movement of the first piston 71 and the second piston 72 in the cylinder 73.

[0056] 6 illustrates the cross section of the fourth flow path 54 to explain the configuration of the first pump chamber 7, but the second pump chamber 8 in the fifth flow path 55 has a similar configuration. That is, the area between the lower end surface of the first piston 81 and the upper end surface of the second piston 82 in the cylinder 83 defines the volume of the second pump chamber 8. This volume increases or decreases in accordance with the up and down movement of the first piston 81 and the second piston 82 in the cylinder 83.

[0057] [Pump operation] The operation of the pump 1 according to the embodiment will be described with reference to FIGS.

[0058] Fig. 7 is a schematic diagram showing the operation of the pump 1 when the coil is energized. Fig. 8 is a schematic diagram showing the periphery of the first pump chamber 7 in the state shown in Fig. 7. The overview of Figs. 7 and 8 is similar to Figs. 5 and 6.

[0059] As shown in Fig. 7, when coil 612 of electromagnet 61 is energized, a magnetic field M1 is generated that passes through the center of coil 612. Magnetic field M1 generated by coil 612 is further strengthened by winding portion 611A of core 611 that is installed to pass through the center of coil 612. In the example of Fig. 7, magnetic field M1 is generated inside winding portion 611A toward the positive X direction.

[0060] The magnetic field M1 thus generated branches into the Z-positive and Z-negative directions along the protruding direction of one of the widened portions 611B disposed on the X-positive side of the winding portion 611A of the core 611. Next, the magnetic field M1 flows toward the X-negative direction inside the first movable plate 62 and the second movable plate 63, which are disposed opposite the upper and lower end faces of the widened portion 611B, respectively. Then, the magnetic fields M1 flow toward the Z-negative direction from the upper and lower end faces of the other widened portion 611B disposed on the X-negative side of the winding portion 611A, inside the widened portion 611B, respectively, toward the center in the Z direction, merge, and then flow back into the winding portion 611A. In other words, the magnetic field M1 illustrated in FIG. 7 flows clockwise on the first movable plate 62 side and counterclockwise on the second movable plate 63 side when viewed from the Y-negative side.

[0061] By generating such a magnetic field M1, the first movable plate 62 is attracted to the electromagnet 61 and moves in the negative Z direction, as shown by arrow A in Fig. 7. Similarly, the second movable plate 63 is attracted to the electromagnet 61 and moves in the positive Z direction, as shown by arrow B.

[0062] Due to this movement of the first movable plate 62 and the second movable plate 63 toward the side attracted to the electromagnet 61, in the first pump chamber 7, the first piston 71 slides in the negative Z direction inside the cylinder 73 as indicated by arrow C. Also, the second piston 72 slides in the positive Z direction inside the cylinder 73 as indicated by arrow D. As a result, the lower end surface of the first piston 71 and the upper end surface of the second piston 72 approach each other, and the volume of the first pump chamber 7 decreases.

[0063] Similarly, in the second pump chamber 8, the first piston 81 slides in the negative Z direction within the cylinder 83 as indicated by arrow E. Also, the second piston 82 slides in the positive Z direction within the cylinder 83 as indicated by arrow F. As a result, the lower end surface of the first piston 81 and the upper end surface of the second piston 82 approach each other, and the volume of the second pump chamber 8 decreases.

[0064] Ideally, the first movable plate 62 and the second movable plate 63 are both moved parallel to the Z direction by the magnetic field M1. Therefore, the sliding distance of the two first pistons 71, 81 installed on the first movable plate 62 is the same as the sliding distance of the two second pistons 72, 82 installed on the second movable plate 63. Therefore, the reduction amounts of the volumes of the first pump chamber 7 and the second pump chamber 8 are also the same.

[0065] Furthermore, as the first movable plate 62 moves toward the side where it is attracted to the electromagnet 61, the central portion 641 of the first leaf spring 64 to which the first movable plate 62 is attached also moves integrally with the first movable plate 62 in the direction of arrow A. At this time, since the fixed end 642 of the first leaf spring 64 is fixed to the support 9, the central portion 641 is displaced in the negative Z direction relative to the fixed end 642. In FIG. 7, the Z-direction position of the first leaf spring 64 in the steady state shown in FIG. 5 is indicated by a dotted line S1. As a result of this displacement, the flexible portion 643 disposed between the central portion 641 and the fixed end 642 is elastically deformed in the negative Z direction, which generates a biasing force f1 in the flexible portion 643 for elastically returning to the positive Z direction, as indicated by the dotted arrow f1 in FIG. 7.

[0066] Similarly, as the second movable plate 63 moves toward the side where it is attracted to the electromagnet 61, the central portion 651 of the second leaf spring 65 to which the second movable plate 63 is attached also moves integrally with the second movable plate 63 in the direction of arrow B. At this time, since the fixed end 652 of the second leaf spring 65 is fixed to the support 9, the central portion 651 is displaced in the positive Z direction relative to the fixed end 652. In FIG. 7, the Z-direction position of the second leaf spring 65 in the steady state shown in FIG. 5 is indicated by a dotted line S2. As a result of this displacement, the flexible portion 653 disposed between the central portion 651 and the fixed end 652 is elastically deformed in the positive Z direction. As a result, a biasing force f2 is generated in the flexible portion 653, causing it to elastically return in the negative Z direction, as indicated by the dotted arrow f2 in FIG. 7.

[0067] When the first pistons 71, 81 and the second pistons 72, 82 move closer to each other as shown in FIG. 7, the volumes of the first pump chamber 7 and the second pump chamber 8 decrease. As a result, as shown in FIG. 8, in the first pump chamber 7, the spherical bodies of the suction valve 74 and the discharge valve 75 are pressed toward the upstream and downstream sides of the fourth flow path 54, respectively, by the fluid in the first pump chamber 7. At this time, the spherical body of the suction valve 74 blocks the upstream side of the fourth flow path 54, so the suction valve 74 is closed. On the other hand, the spherical body of the discharge valve 75 is movable downstream as shown by arrow G, so the discharge valve 75 is opened. As a result, the fluid in the first pump chamber 7 is pressurized and discharged to the downstream side of the fourth flow path 54.

[0068] As described above, the amount of reduction in the volume of the first pump chamber 7 and the second pump chamber 8 is the same, so in the second pump chamber 8, the fluid in the second pump chamber 8 is pressurized and discharged downstream of the fifth flow path 55, similar to the operation of the first pump chamber 7 shown in Figure 7.

[0069] Fig. 9 is a schematic diagram showing the operation of the pump 1 when the coil is switched from energized to de-energized as shown in Fig. 7. Fig. 10 is a schematic diagram showing the periphery of the first pump chamber 7 in the state shown in Fig. 9. The overview of Figs. 9 and 10 is similar to Figs. 5 and 6.

[0070] As shown in FIG. 9, when the coil 612 of the electromagnet 61 is switched from the energized state shown in FIG. 7 to the de-energized state, the magnetic field M1 generated around the electromagnet 61 disappears.

[0071] When the magnetic field M1 disappears, the attractive force that the first movable plate 62 and the second movable plate 63 received from the electromagnet 61 also disappears. Therefore, the first leaf spring 64 operates to return to its original position due to the biasing force f1 generated in the flexible portion 643 of the first leaf spring 64, as indicated by the dotted arrow in FIG. 7 , and the first movable plate 62 also moves in the positive Z direction in response to this operation. However, because the attractive force that was balanced with the biasing force f1 has disappeared, neither the first movable plate 62 nor the first leaf spring 64 remains stationary at the normal position S1, but moves further in the positive Z direction. Finally, as indicated by the arrow H in FIG. 9 , they move in the positive Z direction from the normal position S1 by an amount equal to the amount of movement due to the attraction of the electromagnet 61. Similarly, as indicated by arrow I, the second movable plate 63 and the second leaf spring 65 also move from the steady position S2 toward the negative Z direction due to the biasing force f2 toward the negative Z direction that has been generated in the flexible portion 653.

[0072] As a result of this movement of the first movable plate 62 and the second movable plate 63 away from the electromagnet 61, in the first pump chamber 7, the first piston 71 slides in the positive Z direction within the cylinder 73 as indicated by the arrow J. Also, the second piston 72 slides in the negative Z direction within the cylinder 73 as indicated by the arrow K. As a result, the lower end surface of the first piston 71 and the upper end surface of the second piston 72 move away from each other, and the volume of the first pump chamber 7 increases.

[0073] Similarly, in the second pump chamber 8, the first piston 81 slides in the positive Z direction within the cylinder 83 as indicated by the arrow L. Also, the second piston 82 slides in the negative Z direction within the cylinder 83 as indicated by the arrow M. As a result, the lower end surface of the first piston 81 and the upper end surface of the second piston 82 move away from each other, and the volume of the second pump chamber 8 increases.

[0074] Ideally, the first movable plate 62 and the second movable plate 63 move parallel to each other in the Z direction due to the biasing forces f1 and f2 of the flexible portions 643 and 653. Therefore, the sliding distance of the two first pistons 71 and 81 installed on the first movable plate 62 is the same as the sliding distance of the two second pistons 72 and 82 installed on the second movable plate 63. Therefore, the increase in volume of the first pump chamber 7 and the second pump chamber 8 is also the same.

[0075] 9, when the first pistons 71, 81 and the second pistons 72, 82 move away from each other, the volumes of the first pump chamber 7 and the second pump chamber 8 increase. As a result, as shown in FIG. 10, in the first pump chamber 7, the balls of the suction valve 74 and the discharge valve 75 are each sucked toward the cylinder 73 by the fluid in the first pump chamber 7. At this time, the ball of the discharge valve 75 moves to block the upstream side of the fourth flow path 54 as indicated by arrow N, so the discharge valve 75 is closed. On the other hand, the ball of the suction valve 74 is able to move downstream as indicated by arrow O, so the suction valve 74 is opened. As a result, the fluid upstream of the fourth flow path 54 is sucked into the first pump chamber 7.

[0076] As described above, the increase in volume of the first pump chamber 7 and the second pump chamber 8 is the same, so in the second pump chamber 8, the fluid upstream of the fifth flow path 55 is sucked into the second pump chamber 8, similar to the operation of the first pump chamber 7 shown in Figure 10.

[0077] In the pump 1 of this embodiment, the pump 1 can be driven by controlling the supply of electricity to the coil 612 of the electromagnet 61 so as to alternate between the state when the coil is energized (first state) shown in Figures 7 and 8 and the state when the coil is not energized (second state) shown in Figures 9 and 10.

[0078] With this control, the pressure of the fluid discharged from the pump 1 can be adjusted according to the amount and speed of movement of the first pistons 71, 81 and the second pistons 72, 82. To adjust the pressure, it is necessary to adjust the amount and speed of movement of the first movable plate 62 and the second movable plate 63 on which the first pistons 71, 81 and the second pistons 72, 82 are installed. To adjust the movement of the movable plates 62, 63, it is necessary to adjust the strength (magnetic flux density, etc.) of the magnetic field M1 generated by the electromagnet 61. To adjust the magnetic field M1, it is necessary to control the magnitude of the current flowing through the coil 612 of the electromagnet 61. In other words, with the pump 1 of this embodiment, it is possible to control the discharge of fluid at a desired pressure by controlling the value of the current flowing through the coil 612 of the resonant actuator 6.

[0079] Alternatively, in the pump 1 of this embodiment, it is possible to control the discharge of fluid at a desired pressure by adjusting various structural elements, such as the number of turns of the conducting wire of the coil 612 of the electromagnet 61, the X-direction and Y-direction dimensions of the wound portion 611A of the core 611, the Z-direction protrusion amount and X-direction and Y-direction dimensions of the widened portion 611B of the core 611, the area and shape of the first movable plate 62 and the second movable plate 63 as viewed in the Z direction, and the spring constants of the first leaf spring 64 and the second leaf spring 65.

[0080] The pump 1 of this embodiment includes an electromagnet 61, a first movable plate 62 and a second movable plate 63 that are attracted to the electromagnet 61 by a magnetic field M1 generated by energizing the electromagnet 61, and a first leaf spring 64 and a second leaf spring 65 to which the first movable plate 62 and the second movable plate 63 are attached, respectively, and which urge the first movable plate 62 and the second movable plate 63 in a direction opposite to the attracting action of the first movable plate 62 and the second movable plate 63 to the electromagnet 61 in response to the attracting action of the first movable plate 62 and the second movable plate 63. and second leaf spring 65, a flow path 5 through which a fluid flows, a first pump chamber 7 and a second pump chamber 8 provided on the flow path 5, and an electromagnet 61 that operates to reduce the volume of the first pump chamber 7 and the second pump chamber 8 in response to the suction action of the first movable plate 62 and the second movable plate 63, and when the electromagnet 61 is switched to a non-energized state after the suction action, the electromagnet 61 ... The pump is provided with: a first piston (71, 81) and a second piston (72, 82) as an example of a volume-changing member that operates to increase the volume of the first pump chamber (7) and the second pump chamber (8) in response to the moving away from the stone (61); an intake valve (74) that is provided upstream of the flow path (5) in the first pump chamber (7) and the second pump chamber (8) and opens when the first piston (71, 81) and the second piston (72, 82) move in the direction of increasing the volume of the first pump chamber (7) and the second pump chamber (8) to draw fluid from the upstream side of the flow path (5) into the first pump chamber (7) and the second pump chamber (8); and a discharge valve (75) that is provided downstream of the flow path (5) in the first pump chamber (7) and the second pump chamber (8) and opens when the first piston (71, 81) and the second piston (72, 82) move in the direction of reducing the volume of the first pump chamber (7) and the second pump chamber (8) to discharge fluid from the first pump chamber (7) and the second pump chamber (8) to the downstream side of the flow path (5).

[0081] Here, among the above components, the electromagnet 61 can also be expressed as a “fixed part.” The first and second movable plates 62 and 63, and the first and second leaf springs 64 and 65 can also be expressed as a “movable part that performs a vibrating motion in which it is attracted to the fixed part by a magnetic field generated when the electromagnet 61 is energized, and moves away from the fixed part by a biasing force generated when the electromagnet 61 is not energized.”

[0082] With this configuration, the fixed part (electromagnet 61) generates vibrations in the movable part (first movable plate 62, second movable plate 63, first leaf spring 64, and second leaf spring 65), causing the first piston 71 and the second piston 72 installed in the first pump chamber 7 to slide synchronously within the common cylinder 73. In other words, the resonant actuator 6 can be used as a drive source for the pump 1. This reduces the amount of piston movement required to increase or decrease the volume of the first pump chamber 7 and the second pump chamber 8 compared to conventional solenoid-driven metering pumps, thereby reducing vibration during operation of the pump 1. Furthermore, by setting the switching frequency for switching between the energized and de-energized states of the electromagnet 61 to the same frequency as or near the resonant frequency of the movable part, which is a vibrating element, the movable part can be placed in a resonant state. As a result, the resonant actuator 6 efficiently vibrates the movable part by utilizing the resonance of the movable part in addition to the attraction of the movable part by the electromagnet 61 when the electromagnet 61 is energized. As a result, the efficiency of the pump 1 of this embodiment can be improved.

[0083] In the pump 1 of this embodiment, the first movable plate 62 and the second movable plate 63 are disposed opposite each other with the electromagnet 61 interposed therebetween. The first movable plate 62 and the second movable plate 63 are attached to the first leaf spring 64 and the second leaf spring 65, respectively. That is, the first leaf spring 64 and the second leaf spring 65 are also disposed opposite each other with the electromagnet 61 interposed therebetween. The first pistons 71 and 81 are mounted on the first movable plate 62 and move in conjunction with the movement of the first movable plate 62. The second pistons 72 and 82 are mounted on the second movable plate 63 and move in conjunction with the movement of the second movable plate 63.

[0084] With this configuration, a pair of opposing movable parts (first movable plate 62 and first leaf spring 64, second movable plate 63 and second leaf spring 65) can be vibrated in synchronization with a single electromagnet 61. At this time, since the pair of movable parts are arranged opposite each other with the electromagnet 61 in between, the directions in which they are attracted by the electromagnet 61 are opposite. Therefore, the vibration directions of the pair of movable parts are out of phase. This makes it possible to offset and cancel vibrations generated in the pump 1 by the operation of each movable part.

[0085] In addition, in the pump 1 of this embodiment, the first movable part (first movable plate 62 and first leaf spring 64) and the second movable part (second movable plate 63 and second leaf spring 65) are arranged opposite each other with the fixed part (electromagnet 61) in between. The first pistons 71 and 81 are linked to the operation of the first movable part, and the second pistons 72 and 82 are linked to the operation of the second movable part. The first piston 71 and the second piston 72 are installed in the same first pump chamber 7. Similarly, the first piston 81 and the second piston 82 are installed in the same second pump chamber 8.

[0086] With this configuration, a common pump chamber can be used for the pair of pistons, so only one flow path (fourth flow path 54) and one valve (suction valve 74, discharge valve 75) are required for each pair of first piston 71 and second piston 72. Similarly, only one flow path (fifth flow path 55) and one valve (suction valve 74, discharge valve 75) are required for each pair of first piston 81 and second piston 82. This reduces the number of parts and simplifies the structure of pump 1. Furthermore, because the pump chamber is common, the reaction force acting on the pair of pistons installed in this pump chamber is the same, and there is less misalignment in the movements of the pair of moving parts arranged opposite each other. This allows the number of pump chambers to be increased while reducing the number of parts, thereby improving pump efficiency.

[0087] Here, the effect of core 611 of electromagnet 61 according to this embodiment will be described with reference to Fig. 11 in addition to Fig. 7. Fig. 11 is a schematic diagram showing magnetic field M2 generated in electromagnet 61A using flat core 611C as a comparative example.

[0088] In the comparative example of Fig. 11, electromagnet 61A has a flat core 611C. Core 611C of the comparative example differs from core 611 of the embodiment in that it does not have widened portion 611B as shown in Fig. 7 and other figures. Core 611C is formed so that the dimension in the Z direction is uniform throughout the entire X direction. In other words, core 611C has a shape in which wound portion 611A of core 611 of the embodiment extends to both sides of the range in the X direction where widened portion 611B is located.

[0089] 11 , when a magnetic field M2 is generated inside the core 611C in the X-positive direction by energizing the coil 612, this magnetic field M2 first advances in the X-positive direction from the end of the core 611C on the X-positive side into the space of the resonant actuator 6. Then, it branches off toward the Z-positive side and the Z-negative side, curves, reverses its direction, enters the interior from the X-positive side ends of the first movable plate 62 and the second movable plate 63, and heads toward the X-negative side. Then, it advances again in the X-negative direction into the space of the resonant actuator 6 from the X-negative side ends of the first movable plate 62 and the second movable plate 63, curves toward the Z-negative side and the Z-positive side, reverses its direction to the X-positive side, and merges with the magnetic field M2 before flowing into the X-negative side end of the core 611C.

[0090] 11 is the same as the magnetic field M1 of the embodiment shown in Fig. 7 in that, when viewed from the Y negative direction, the magnetic field M2 of the comparative example flows clockwise on the first movable plate 62 side and counterclockwise on the second movable plate 63 side. However, the magnetic field M2 of the comparative example flows more in the space of the resonant actuator 6 than the magnetic field M1 of the embodiment, that is, the air gap is larger, and therefore the magnetic resistance tends to increase.

[0091] 7, the electromagnet 61 of this embodiment is provided with an expanded width portion 611B in the core 611, so that the air gap in the magnetic field M1 can be limited to the gap between the upper end surface of the expanded width portion 611B and the first movable plate 62, and the gap between the lower end surface of the expanded width portion 611B and the second movable plate 63. This reduces the air gap in the magnetic field M1, and reduces the magnetic resistance, so that the magnetic force can be generated more efficiently than in the comparative example.

[0092] In this embodiment, the core 611 of the electromagnet 61 is formed by stacking multiple electromagnetic steel plates in the Y direction, as shown in Figures 3 and 4. Adjacent electromagnetic steel plates are bonded together with an adhesive, and this adhesive portion forms an air gap, which creates magnetic resistance that makes it difficult for magnetic flux to flow. Since the magnetic flux generated by the coil 612 flows through the core 611 toward the movable plates 62 and 63, if the stacking direction is the Y direction as in this embodiment, the air gap is positioned parallel to the flow of the magnetic flux, which results in less obstruction to the flow of magnetic flux and improved energy transmission efficiency.

[0093] On the other hand, in a configuration in which the lamination direction is 90 degrees different from that of this embodiment, that is, in which the lamination direction is the X direction, an air gap is placed in a position that obstructs the flow of magnetic flux, resulting in a decrease in efficiency.

[0094] Next, the effects of the shapes of the movable plates 62, 63 and the leaf springs 64, 65 in this embodiment will be described with reference to Fig. 12. Fig. 12 is a plan view of the internal structure of the housing 2 of the pump 1 as viewed from the Z positive side. Fig. 12 illustrates the interior of the housing 2 as viewed from the first leaf spring 64 side, with the main surface of the housing 2 on the Z positive side removed from the pump 1 shown in Fig. 1.

[0095] If the direction (Y direction) perpendicular to the direction (X direction) of the magnetic field M1 generated by the electromagnet 61 is defined as the width direction, as shown in Fig. 12, the width dimension W1 of at least the flexible portion 643 of the first leaf spring 64 is larger than the width dimension W2 of the first movable plate 62. The same applies to the relationship between the second movable plate 63 and the second leaf spring 65, which are hidden at the back of Fig. 12, and the width dimension W1 of at least the flexible portion 653 of the second leaf spring 65 is larger than the width dimension W2 of the second movable plate 63.

[0096] As described with reference to FIG. 7 , when the electromagnet 61 is energized during operation of the resonant actuator 6, the first movable plate 62 and the second movable plate 63 ideally move parallel to each other in a direction (Z direction) toward the electromagnet 61 due to the magnetic field M1 generated by the electromagnet 61. However, if the magnetic field M1 has an uneven magnetic flux density across the width of the movable plates 62 and 63, the first movable plate 62 and the second movable plate 63 may be twisted during operation, such as tilting in the X direction or the Y direction. Therefore, by forming the width dimension W1 of the leaf springs 64 and 65 larger than that of the movable plates 62 and 63 as in this embodiment, the leaf springs 64 and 65 can more easily absorb the twisting of the movable plates 62 and 63 during operation, thereby enabling more stable translation of the first movable plate 62 and the second movable plate 63. As a result, the pump 1 of this embodiment, which uses the resonant actuator 6 as a drive source, can reduce noise and vibration.

[0097] Furthermore, the first pump chamber 7 and the second pump chamber 8 are disposed opposite each other at positions where a pair of first pistons 71, 81 are provided on both ends of the first movable plate 62 in the direction of the magnetic field M1 (X direction). Similarly, the second movable plate 63 is disposed opposite each other at positions where a pair of second pistons 72, 82 are provided on both ends of the second movable plate 63 in the direction of the magnetic field M1 (X direction). In this configuration having two pump chambers, two pistons are provided on one movable plate. Therefore, when the relationship between the widthwise dimension W1 of the leaf springs 64, 65 and the widthwise dimension W2 of the movable plates 62, 63 is satisfied, sliding of the two pistons provided on one movable plate relative to the pump chambers 7, 8 can be stabilized, thereby particularly effective in suppressing twisting of the movable plates 62, 63.

[0098] Next, the effects of the arrangement of the first pump chamber 7 and the second pump chamber 8 will be described. As shown in FIGS. 2 and 7 , among the flow paths 5 of the pump 1, the fourth flow path 54 including the first pump chamber 7 is arranged adjacent to a position opposite (on the negative X-direction side) the wound portion 611A of the core 611 of the electromagnet 61, across the widened portion 611B on the negative X-direction side of the core 611, and the flow direction is arranged along the width direction (Y direction). Similarly, the fifth flow path 55 including the second pump chamber 8 among the flow paths 5 of the pump 1 is arranged adjacent to a position opposite (on the positive X-direction side) the wound portion 611A of the core 611, across the widened portion 611B on the positive X-direction side of the core 611 of the electromagnet 61, and the flow direction is arranged along the width direction (Y direction).

[0099] Therefore, the first piston 71 inserted into the first pump chamber 7 is disposed adjacent to a position on the opposite side (X-negative direction side) of the wound portion 611A of the first movable plate 62, across the widened portion 611B on the X-negative direction side of the electromagnet 61. The second piston 72 also inserted into the first pump chamber 7 is disposed adjacent to a position on the opposite side (X-negative direction side) of the wound portion 611A of the second movable plate 63, across the widened portion 611B on the X-negative direction side of the electromagnet 61. Similarly, the first piston 81 inserted into the second pump chamber 8 is disposed adjacent to a position on the opposite side (X-positive direction side) of the wound portion 611A of the first movable plate 62, across the widened portion 611B on the X-positive direction side of the electromagnet 61. The second piston 82, which is also inserted into the second pump chamber 8, is positioned adjacent to the second movable plate 63 on the opposite side (X-positive side) of the winding portion 611A, sandwiching the widened portion 611B on the X-positive side of the electromagnet 61.

[0100] By providing widened portions 611B at both ends in the X direction of core 611 of electromagnet 61, a magnetic field M1 is generated such that magnetic flux passes through the upper and lower end surfaces of widened portion 611B in a concentrated manner, as shown in Fig. 7. That is, when electromagnet 61 is energized, the first movable plate 62 receives the strongest attractive force at a portion facing the upper end surface of widened portion 611B, and the second movable plate 63 receives the strongest attractive force at a portion facing the lower end surface of widened portion 611B. Therefore, by arranging first pistons 71, 81 and second pistons 72, 82 adjacent to widened portion 611B, each piston can be arranged near a portion of first movable plate 62 and second movable plate 63 that receives the strongest attractive force from electromagnet 61. This makes it possible to efficiently apply external force in the sliding direction from the first movable plate 62 and the second movable plate 63 to the first pistons 71, 81 and the second pistons 72, 82, thereby improving the operating efficiency of both the first pump chamber 7 and the second pump chamber 8.

[0101] Furthermore, by arranging the first pistons 71, 81 and the second pistons 72, 82 near the portions of the first movable plate 62 and the second movable plate 63 that receive the strongest attractive force from the electromagnet 61, it is possible to prevent the movement directions of the first pistons 71, 81 and the second pistons 72, 82 from being twisted during the attraction operation due to the attractive force generated when the electromagnet 61 is energized. This makes it possible to align the movement directions of the first pistons 71, 81 and the second pistons 72, 82 with the axial direction (Z direction) of the cylinders 73, 83 of the respective pump chambers 7, 8, thereby further improving the operating efficiency of the first pump chamber 7 and the second pump chamber 8. As a result, the pump 1 of this embodiment can achieve improved performance and high efficiency in a configuration that uses the resonant actuator 6 as a drive source.

[0102] Furthermore, the first pump chamber 7 is disposed adjacent to a position on the opposite side (X negative direction) of the wound portion 611A of the core 611 of the electromagnet 61, with one of the pair of widened portions 611B of the core 611 sandwiched therebetween, and the second pump chamber 8 is disposed adjacent to a position on the opposite side (X positive direction) of the wound portion 611A, with the other of the pair of widened portions 611B sandwiched therebetween. In this configuration having two pump chambers, two pistons are installed on one movable plate. Therefore, by arranging the pump chambers 7, 8 adjacent to the widened portion 611B, it is possible to more easily equalize the external forces applied to the two pistons installed on one movable plate, and it is possible to more easily synchronize the sliding of the pistons in the pump chambers 7, 8. This particularly improves the operating efficiency of the pump chambers.

[0103] As shown in FIG. 2 and other figures, it is preferable that both the first pump chamber 7 and the second pump chamber 8 be arranged on the axis of symmetry CA of the housing 2. As shown in FIG. 7 and other figures, the coil 612 of the electromagnet 61 is arranged so that its central axis coincides with the axis of symmetry CA, and therefore, magnetic flux tends to be most concentrated on the axis of symmetry CA near the center of the coil 612. Therefore, the first movable plate 62 and the second movable plate 63 are likely to receive the strongest attractive force from the electromagnet 61 on the axis of symmetry CA. Therefore, if the first pump chamber 7 and the second pump chamber 8 are arranged on the axis of symmetry CA, the first pistons 71, 81 and the second pistons 72, 82 are also arranged on the axis of symmetry CA. This makes it possible for the first movable plate 62 and the second movable plate 63 to efficiently apply an external force in the sliding direction to the first pistons 71, 81 and the second pistons 72, 82, thereby further improving the operating efficiency of the first pump chamber 7 and the second pump chamber 8.

[0104] [Detailed configuration of pump rooms 7 and 8] Next, the detailed configuration of the pump chambers 7 and 8 according to this embodiment will be further described with reference to FIGS.

[0105] FIG. 13 is a schematic diagram showing an enlarged view of the pump chambers 7 and 8 according to this embodiment. The overview of FIG. 13 corresponds to FIG. 6. FIG. 13 shows an enlarged view of the portion of the first pump chamber 7 in the steady state that is on the Z positive side of the axis of symmetry CB. In FIG. 13, the upper end side (Z positive side) of the first piston 71 is not shown, and the lower side (Z negative side) of the fourth flow path 54, the cylinder 73, the suction valve 74, and the discharge valve 75 are not shown. In FIG. 13 and in FIGS. 14 and 15 described below, the fluid to be transferred flowing through the flow path 5 is shown with a dotted pattern.

[0106] As shown in FIG. 13 , the first pump chamber 7 includes an O-ring 76. The O-ring 76 is an example of a first seal member that is provided on the outer peripheral surface of the first piston 71 and seals the gap between the outer peripheral surface of the first piston 71 and the inner peripheral surface of the cylinder 73. The O-ring 76 is disposed on the outer peripheral surface of the first piston 71 in the Z direction so that the outer peripheral portion of the O-ring 76 is always in contact with the inner peripheral surface of the cylinder 73 within the sliding range of the first piston 71 within the cylinder 73. For example, as shown in FIG. 13 , the O-ring 76 is preferably disposed on the outer peripheral surface of the first piston in the Z direction near the tip end of the first piston 71 on the fourth flow path 54 side.

[0107] The O-ring 76 is an annular member made of, for example, rubber, and is installed on the outer circumferential surface of the first piston 71 along the circumferential direction of the outer circumferential surface. If the cross-sectional shape of the first piston 71 as viewed in the Z direction is circular, the O-ring 76 will also be annular. By providing the O-ring 76 on the first piston 71 in this manner, it is possible to prevent fluid in the first pump chamber 7 from leaking out in the positive Z direction from the gap between the first piston 71 and the cylinder 73 when the first piston 71 slides inside the cylinder 73.

[0108] The first pump chamber 7 further includes a diaphragm seal 77. The diaphragm seal 77 is provided outside the first pump chamber 7 relative to the O-ring 76 (first seal member), and is an example of a second seal member that prevents fluid leaking from the O-ring 76 from further leaking out. The diaphragm seal 77 is an annular elastic membrane, with a central end 77A connected to the outer circumferential surface of the first piston 71 and a centrifugal end 77B connected to the support body 9.

[0109] In the example of FIG. 13 , a recess 91 is formed in the support 9 around the opening on the Z positive side of the cylinder 73, recessed evenly toward the Z negative side. The recess 91 has a bottom surface 91A and an inner surface 91B. The inner surface 91B is a peripheral surface that extends in the Z positive direction from the bottom surface 91A along the outer shape of the bottom surface 91A and faces the central axis CO of the cylinder 73. A central end 77A of the diaphragm seal 77 is connected and fixed to a predetermined position in the Z direction on the outer peripheral surface of the first piston 71 and is movable in the Z direction as the first piston 71 slides. A centrifugal end 77B of the diaphragm seal 77 is connected and fixed to the inner surface 91B of the recess 91, and is maintained in the same position in the Z direction regardless of the sliding of the first piston 71.

[0110] The diaphragm seal 77 can also be described as a membrane seal that is attached to two inner and outer parts that move relative to each other (the first piston 71 and the support body 9 in this embodiment) and deforms to accommodate the relative movement. The diaphragm seal 77 is made of a flexible and bendable material, such as rubber.

[0111] When the cross-sectional shapes of the first piston 71 and the cylinder 73 as viewed in the Z direction are circular, the outer shape of the bottom surface 91A of the recess 91 is also circular, and further, the recess 91 is formed concentrically with the first piston 71 and the cylinder 73 so that the axis CO of the first piston 71 and the cylinder 73 is the center. Therefore, the inner surface 91B of the recess 91 also has a circular hole shape when viewed from the Z direction. In this case, the shape of the diaphragm seal 77 as viewed in the Z direction is formed in a doughnut shape. The inner diameter of the circular hole provided at the center of the doughnut shape is formed to be smaller than the diameter dimension of the first piston 71. The outer diameter of the doughnut shape is formed to be larger than the inner diameter of the inner surface 91B of the recess 91 of the support body 9.

[0112] With the above-described configuration, the opening on the Z positive side of the recess 91 in the support body 9 is completely blocked by the diaphragm seal 77 and the first piston 71 connected to its center. This prevents the fluid that flows through the fourth flow path 54 and leaks from the O-ring 76 from further leaking out. In other words, in this embodiment, the O-ring 76 (first seal member) and the diaphragm seal 77 (second seal member) provide doubly effective prevention of fluid leakage from the first pump chamber 7.

[0113] The first pump chamber 7 further includes a return path 78. The return path 78 returns the fluid leaking from the O-ring 76 to the flow path 5 (fourth flow path 54) upstream of the first pump chamber 7 (more specifically, the suction valve 74).

[0114] 13, the return flow path 78 has a horizontal flow path 78A and a vertical flow path 78B. The horizontal flow path 78A is formed by extending in the centrifugal direction from the edge end portion on the center side of the bottom surface 91A of the recess 91. The extension direction of the horizontal flow path 78A is preferably the same direction as the fourth flow path 54, and is a direction from the position of the cylinder 73 toward the upstream side of the fourth flow path 54. In the example of FIG. 13, the horizontal flow path 78A is a groove provided on the bottom surface 91A of the recess 91.

[0115] The vertical flow path 78B is a through-hole that penetrates between the recess 91 of the support body 9 and the fourth flow path 54. The vertical flow path 78B extends, for example, in the Z direction, and is formed such that one end on the Z positive side is connected to the centrifugal side end of the horizontal flow path 78A and the other end on the Z negative side is open to the fourth flow path 54. The opening of the vertical flow path 78B to the fourth flow path 54 is located upstream of the suction valve 74 of the first pump chamber 7 (on the Y negative side in the example of FIG. 13 ).

[0116] One end of the return path 78 on the center side of the horizontal path 78A is opened closer to the first pump chamber 7 (fourth path 54 side) than the diaphragm seal 77 (second seal member) in the sliding direction of the first piston 71.

[0117] With these configurations, the return flow path 78 can collect the fluid leaking from the O-ring 76 into the horizontal flow path 78A of the return flow path 78, flow it toward the vertical flow path 78B, and then flow it into the vertical flow path 78B of the return flow path 78, allowing it to flow into the fourth flow path 54, and return it to the upstream side of the first pump chamber 7.

[0118] Next, the reflux operation of the fluid leaking from the O-ring 76 will be described with reference to FIGS.

[0119] Fig. 14 is a schematic diagram showing a state in which the first piston 71 is moving in a direction that reduces the volume of the first pump chamber 7. The overview of Fig. 14 is similar to Fig. 8. That is, Fig. 14 illustrates a state in which the coil 612 of the electromagnet 61 of the resonant actuator of the pump 1 is energized, and the first piston 71 slides in the negative Z direction (downward in the figure) within the cylinder 73 as indicated by arrow C.

[0120] As the first piston 71 slides downward, the O-ring 76 moves downward within the cylinder 73 together with the first piston 71 while maintaining its installation position on the outer surface of the first piston 71 and while maintaining contact with the inner surface of the cylinder 73.

[0121] Furthermore, a center-side end 77A of the diaphragm seal 77 is connected and fixed to the outer peripheral surface of the first piston 71, and therefore moves downward together with the first piston 71. On the other hand, a centrifugal-side end 77B of the diaphragm seal 77 is connected and fixed to the support body 9 (the inner surface 91B of the recess 91), and therefore its position in the Z direction is maintained. As a result of this connection state of both ends of the diaphragm seal 77, when the first piston 71 slides downward, the center-side end 77A of the diaphragm seal 77 descends relative to the centrifugal-side end 77B, and the center-side portion of the diaphragm seal 77 assumes a shape that is recessed toward the bottom surface 91A of the recess 91, as shown in FIG.

[0122] 14, as the volume of the first pump chamber 7 decreases, the spherical bodies of the suction valve 74 and the discharge valve 75 are pressed toward the upstream and downstream sides of the fourth flow path 54, respectively, by the fluid in the first pump chamber 7. At this time, the spherical body of the suction valve 74 blocks the upstream side of the fourth flow path 54, so the suction valve 74 is closed. On the other hand, the spherical body of the discharge valve 75 is movable downstream as indicated by arrow G, so the discharge valve 75 is opened. As a result, the fluid in the first pump chamber 7 is pressurized and discharged to the downstream side of the fourth flow path 54.

[0123] 14, when the fluid in the first pump chamber 7 is pressurized, as indicated by the dotted arrow in the figure, the pressurized fluid may pass through the contact portion between the O-ring 76 and the cylinder 73 and leak upward (toward the positive Z direction) from the O-ring 76. In this embodiment, a diaphragm seal 77 is provided on the outside of the O-ring 76 as another sealing member, and therefore the fluid that has leaked from the O-ring 76 is prevented by the diaphragm seal 77 from further leaking out.

[0124] Fig. 15 is a schematic diagram showing a state in which the first piston 71 is moving in a direction that increases the volume of the first pump chamber 7. The overview of Fig. 15 is similar to that of Fig. 10. That is, Fig. 15 illustrates a state in which the coil 612 of the electromagnet 61 of the resonant actuator of the pump 1 is switched from the energized state shown in Fig. 14 to the de-energized state, and the first piston 71 slides in the cylinder 73 in the positive Z direction (upward in the figure) as indicated by arrow J.

[0125] As the first piston 71 slides upward, the O-ring 76 moves upward within the cylinder 73 together with the first piston 71 while maintaining its installation position on the outer circumferential surface of the first piston 71 and while maintaining contact with the inner circumferential surface of the cylinder 73. Due to this upward movement of the O-ring 76, the fluid leaking from the O-ring 76 illustrated in Fig. 14 is pushed upward by the O-ring 76 and flows out onto the bottom surface 91A of the recess 91, and is collected in the horizontal flow path 78A of the return flow path 78 provided on the bottom surface 91A.

[0126] Furthermore, a center-side end 77A of the diaphragm seal 77 is connected and fixed to the outer peripheral surface of the first piston 71, and therefore moves upward together with the first piston 71. On the other hand, a centrifugal-side end 77B of the diaphragm seal 77 is connected and fixed to the support body 9 (the inner surface 91B of the recess 91), and therefore its position in the Z direction is maintained. As a result of this connection state of both ends of the diaphragm seal 77, when the first piston 71 slides upward, the center-side end 77A of the diaphragm seal 77 rises relative to the centrifugal-side end 77B, as shown in FIG. 15, and the center-side portion of the diaphragm seal 77 assumes a convex shape that bulges upward.

[0127] 15 , as the volume of first pump chamber 7 increases, the spheres of suction valve 74 and discharge valve 75 are each sucked toward cylinder 73 by the fluid in first pump chamber 7. At this time, the sphere of discharge valve 75 moves to block the upstream side of fourth flow path 54 as shown by arrow N, so discharge valve 75 is closed. On the other hand, the sphere of suction valve 74 is able to move downstream as shown by arrow O, so suction valve 74 is opened. As a result, the fluid upstream of fourth flow path 54 is sucked into first pump chamber 7.

[0128] Furthermore, when the fluid upstream of the fourth flow path 54 is being sucked into the first pump chamber 7, the fluid accumulated in the return flow path 78 is also sucked in. As a result, as shown by the dotted arrow in Figure 15, the fluid collected in the horizontal flow path 78A of the return flow path 78 flows to the centrifugal side, then flows downward through the vertical flow path 78B, flows from the vertical flow path 78B into the fourth flow path 54, and is sucked into the first pump chamber 7 again.

[0129] 13 to 15 illustrate the configuration and operation of the first piston 71 and its surroundings by enlarging a portion of the first pump chamber 7 on the positive Z side of the axis of symmetry CB. The configuration and operation of the second piston 72 on the negative Z side of the axis of symmetry CB in the first pump chamber 7 are similar. In the example illustrated in FIGS. 13 to 15, the second piston 72 is disposed on the lower side of the support 9. Therefore, if a recess 91 is provided, the opening of the recess 91 faces downward. In this case, the horizontal flow path 78A is preferably a through-hole provided inside the support 9, similar to the vertical flow path 78B, instead of a groove on the bottom surface 91A, so that fluid can flow through the horizontal flow path 78A of the return flow path 78. The configuration of the first pump chamber 7 has been described using a cross section of the fourth flow path 54 in FIGS. 13 to 15. The second pump chamber 8 in the fifth flow path 55 also has a similar configuration.

[0130] The pump 1 according to this embodiment includes a flow path 5 through which a fluid to be transferred flows, pump chambers 7 and 8 provided on the flow path 5, pistons 71, 72, 81, and 82 that slide within cylinders 73 and 83 to increase and decrease the volume of the pump chambers 7 and 8, O-rings 76 that are provided on the outer surfaces of the pistons 71, 72, 81, and 82 and seal gaps between the pistons and the inner surfaces of the cylinders 73 and 83, a diaphragm seal 77 that is provided outside the O-ring 76 from the pump chambers 7 and 8 and prevents further leakage of fluid that has leaked from the O-ring 76 to the outside, and a return flow path 78 that returns the fluid that has leaked from the O-ring 76 to the flow path 5 upstream of the pump chambers 7 and 8. One end of the return flow path 78 that faces the cylinders 73 and 83 is open toward the pump chambers 7 and 8 relative to the diaphragm seal 77 in the sliding direction of the pistons.

[0131] Here, if the O-rings 76 provided on the outer surfaces of the pistons 71, 72, 81, 82 are made larger relative to the gaps between them and the inner surfaces of the cylinders 73, 83 (increasing the diameter of the circumferential cross-sectional shape), the performance (sealing performance) of the O-rings 76 to prevent fluid from leaking from the pump chambers 7, 8 to the outside via the cylinders 73, 83 will improve. However, while sealing performance can be improved in this case, the sliding resistance of the pistons increases by the amount of the O-ring 76 being enlarged, reducing the vibration efficiency of the pump 1. On the other hand, if the O-ring 76 is made smaller, sliding resistance will decrease and vibration efficiency will increase, but fluid will be more likely to leak from the O-ring 76, reducing sealing performance.

[0132] Therefore, in this embodiment, a double structure including a diaphragm seal 77 in addition to the O-ring 76 allows the O-ring 76 to prioritize suppressing an increase in the sliding resistance of the piston and a decrease in the vibration efficiency of the pump 1, rather than improving sealing performance. The diaphragm seal 77 also ensures sealing performance for the entire pump 1. As a result, the pump 1 according to this embodiment can suppress an increase in the sliding resistance of the piston, suppress a decrease in the vibration efficiency of the pump 1, and improve sealing performance. Note that fluid leaks from the O-ring 76, which may result in a slight decrease in the flow efficiency of the pump 1. However, the amount of leakage from the O-ring 76 is very small compared to the flow rate (main flow rate) of the fluid discharged from the pump chambers 7 and 8. Consequently, the overall efficiency of the pump 1 according to this embodiment is improved. As a result, the pump 1 according to this embodiment can suppress a decrease in pump efficiency even when fluid leaks from the pump chambers 7 and 8.

[0133] Furthermore, in this embodiment, by providing a return flow path 78 that opens closer to the pump chambers 7, 8 than the diaphragm seal 77 in the sliding direction of the piston, it is possible to return the fluid that leaks from the O-ring 76 back to the pump chambers 7, 8. This makes it possible to prevent the fluid that has leaked out of the pump chambers 7, 8 from remaining in a volume that exceeds the volume of the space between the O-ring 76 and the diaphragm seal 77, thereby preventing damage to the diaphragm seal 77 and more reliably ensuring sealing performance.

[0134] Even when O-ring 76 is provided to prevent fluid leakage, leakage can occur when the piston slides at high speed, for example. Such a situation may occur when pump 1 is applied to espresso machine 100 (see FIG. 16), which requires a configuration that increases the pressure of the fluid within pump 1 and discharges the fluid at high pressure (high-pressure pump). Therefore, the above-described effects of pump 1 of this embodiment are particularly pronounced when pump 1 is a high-pressure pump.

[0135] [Application example of Pump 1] 16 is a diagram showing an application example of the pump 1 according to the embodiment. As shown in FIG. 16, the pump 1 according to the embodiment can be applied to a beverage supplying device such as an espresso machine 100.

[0136] The espresso machine 100 includes a tank 101, a heater 102, a damper 103, and a brewing unit 104.

[0137] Tank 101 stores water used for espresso. Tank 101 and pump 1, pump 1 and heater 102, and heater 102 and extraction unit 104 are connected by flow paths 107 that transport water supplied from tank 101.

[0138] The pump 1 pressurizes water delivered from the tank 101 and sends it to the heater 102. In the case of the espresso machine 100, the pump 1 preferably increases the pressure of the water to, for example, 9 atmospheres.

[0139] The heater 102 heats the pressurized water transported from the tank 101 and sends it to the extraction unit 104 .

[0140] Ground coffee beans 105 are packed in the lower part of the inside of extraction unit 104 and are pressed downward by damper 103. Pressurized hot water heated by heater 102 is supplied to coffee bean powder 105 thus pressed, and coffee is extracted from extraction hole 106 at the bottom end of extraction unit 104.

[0141] Espresso machines require the use of a high-pressure pump to extract coffee at high pressure. For this reason, conventional espresso machines often use a solenoid-driven metering pump. However, solenoid-driven metering pumps have problems such as high vibration and low efficiency.

[0142] In contrast, the pump 1 of this embodiment is configured to use the resonant actuator 6 as the drive source, and therefore can solve the problems of the conventional solenoid-driven metering pumps described above, and can provide an espresso machine 100 that is more convenient.

[0143] The pump 1 can be applied to any beverage dispenser that requires pressure boosting, in addition to the espresso machine 100. Such a beverage dispenser may include at least a tank for storing a beverage, the pump 1 according to the embodiment for sucking the beverage from the tank and discharging it at a predetermined pressure, and a discharge unit (corresponding to the extraction unit 104 in the example of FIG. 13) for discharging the beverage discharged from the pump 1.

[0144] The pump 1 can also be applied to any device other than a beverage supply device that requires pressure boosting, such as industrial manufacturing equipment (such as semiconductor manufacturing equipment), medical equipment, household equipment (such as toilets, washbasins, and baths), and agricultural equipment.

[0145] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0146] The pump 1 according to the embodiment may have a structure other than that described above as long as it is capable of at least pumping out the fluid in the flow path 5. For example, the above embodiment illustrates a configuration in which the intake port 3 is disposed on the side surface 23 of the housing 2 and the exhaust port 4 is disposed on the side surface 24, but the locations of the intake port 3 and the exhaust port 4 may be changed as desired.

[0147] Furthermore, in the above embodiment, a configuration in which the first pump chamber 7 and the second pump chamber 8 are both arranged on the axis of symmetry CA is exemplified, but the arrangement of the first pump chamber 7 and the second pump chamber 8 only needs to be at least the fourth flow path 54 and the fifth flow path 55, and they may also be at a position other than the axis of symmetry CA.

[0148] In addition, in the above embodiment, a configuration in which two pistons, a first piston 71, 81 and a second piston 72, 82, are arranged in each pump chamber 7, 8 is exemplified, but a configuration in which only a single piston is installed in one pump chamber may also be used.

[0149] Furthermore, in the above embodiment, the configuration in which two pump chambers 7 and 8 are provided in the flow path 5 is exemplified, but the configuration in which only a single pump chamber is provided in the flow path 5 may also be used.

[0150] In addition, in the above embodiment, a configuration was exemplified in which two movable parts, a first movable part (first movable plate 62 and first leaf spring 64) and a second movable part (second movable plate 63 and second leaf spring 65), are provided on either side of a single fixed part including an electromagnet 61, but a configuration in which only one of the pair of movable parts is provided may also be used.

[0151] In the above embodiment, a fluid (liquid) is used as the object to be transferred that flows through the flow path 5 of the pump 1, but the object to be transferred may be a gas.

[0152] In the above embodiment, a double structure using the O-ring 76 and the diaphragm seal 77 was exemplified as a structure for preventing leakage of the object to be transferred from the pump chambers 7 and 8. However, other elements may be used. The O-ring 76, which is an annular rubber member serving as an example of a "first seal member," may be replaced with another element capable of fulfilling the function of "being provided on the outer circumferential surfaces of the pistons 71, 72, 81, and 82 and sealing the gap between the outer circumferential surfaces of the pistons 71, 72, 81, and 82 and the inner circumferential surfaces of the cylinders 73 and 83." Examples of such elements include metal piston rings and annular resin members other than rubber. The diaphragm seal 77, which is an annular elastic membrane serving as an example of a "second seal member," may be replaced with another element capable of fulfilling the function of "being provided outside the pump chambers 7 and 8 relative to the first seal member and preventing further leakage of fluid leaking from the first seal member." Examples of such elements include a bellows. Furthermore, the diaphragm seal 77 may be made of a combination of rubber and a base fabric rather than rubber alone.

[0153] In the above embodiment, the return flow path 78 has a horizontal flow path 78A and a vertical flow path 78B, but the configuration is not limited to this as long as it can return at least the fluid leaking from the O-ring 76 (first seal member) to the flow path 5 upstream of the first pump chamber 7. For example, if the inner diameter of the fourth flow path 54 upstream of the first pump chamber 7 (suction valve 74) is larger than the configuration shown in FIG. 13 etc. so that the upper end of the inner circumferential surface of the flow path is higher than the position of the horizontal flow path 78A in the Z direction, the return flow path 78 may have only the horizontal flow path 78A, and the end of the horizontal flow path 78A on the Y negative direction side (upstream side) may open to the fourth flow path 54. [Explanation of symbols]

[0154] 1 pump 5 Flow path 6 Resonant Actuators 61 Electromagnet (fixed part) 62 First movable plate (movable part) 63 Second moving plate (moving part) 64 First leaf spring (moving part) 65 Second leaf spring (moving part) 7. First Pump Room 71 First piston 72 Second piston 73 cylinders 8. Second Pump Room 81 First piston 82 Second piston 83 cylinders 9 Support (fixed object) 100 Espresso machine (beverage supply device) 101 Tank 104 Extraction unit (discharge part) 76 O-ring (first seal member) 77 Diaphragm seal (second seal member) 78 Circulation Channel

Claims

1. a flow path through which an object to be transferred flows; a pump chamber provided on the flow path; a piston that slides within a cylinder to reduce or increase the volume of the pump chamber; a first seal member provided on an outer circumferential surface of the piston and configured to seal a gap between the outer circumferential surface of the piston and an inner circumferential surface of the cylinder; a second seal member provided outside the pump chamber relative to the first seal member, and configured to prevent the object to be transferred leaking from the first seal member from further leaking to the outside; a return flow path that returns the object to be transferred that has leaked from the first seal member to the flow path upstream of the pump chamber; Equipped with One end of the return passage is provided to open closer to the pump chamber than the second seal member in the sliding direction of the piston. pump.

2. The housing and a fixed object installed inside the housing, the flow path and the pump chamber are formed inside the fixed object, the first seal member is an annular member made of rubber, The second seal member is an annular elastic membrane, and has a central end connected to the outer circumferential surface of the piston and a centrifugal end connected to the fixed object.

2. The pump of claim 1.

3. The object to be transferred is a fluid.

2. The pump of claim 1.

4. a fixed portion on which an electromagnet is installed; a movable part that is attracted to the fixed part by a magnetic field generated by energizing the electromagnet, and that performs a vibration motion of moving away from the fixed part by a biasing force generated when the electromagnet is not energized; Equipped with the piston operates to reduce the volume of the pump chamber in response to the action of the movable part being attracted to the fixed part, and operates to increase the volume of the pump chamber in response to the action of the movable part being separated from the fixed part.

2. The pump of claim 1.

5. a tank for storing a beverage; a pump according to any one of claims 1 to 4, which sucks the beverage in the tank and discharges it at a predetermined pressure; a discharge portion that discharges the beverage discharged from the pump; A beverage supply device comprising:

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