Pump and beverage supply device

Abstract

A pump includes a fixed portion including an electromagnet; movable portions that are attracted toward the fixed portion by a magnetic field generated at a time of energization of the electromagnet, and that perform a vibrating motion moving away from the fixed portion by a biasing force at a time of energization of the electromagnet; a flow channel through which a fluid flows; a first pump chamber and a second pump chamber disposed in the flow channel; a cooling flow channel disposed in a portion of the flow channel; and heat-absorption members that are cooled by the fluid flowing through the cooling flow channel and absorb heat from a coil or a core of the electromagnet.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a pump and beverage supply apparatus.BACKGROUND

[0002] Pumps used in beverage supply apparatuses such as home espresso machines and inexpensive commercial espresso machines often employ pumps using electromagnetic actuators as drive sources. The electromagnetic actuator is an actuator that operates using magnetic force generated by an electromagnet as energy (e.g., Patent Document 1).RELATED-ART DOCUMENTPATENT DOCUMENT

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-180332SUMMARYPROBLEM TO BE SOLVED BY THE INVENTION

[0004] When a pump employing an electromagnetic actuator is operated continuously, the temperature of a coil of an electromagnet constituting the electromagnetic actuator may increase, resulting in deterioration of pump performance.

[0005] An object of the present disclosure is to provide a pump and a beverage supply apparatus capable of suppressing performance degradation caused by heat generation of a drive source.MEANS FOR SOLVING THE PROBLEM

[0006] A pump according to one embodiment of the present disclosure includes: a fixed portion in which an electromagnet is disposed; movable portions that are attracted to the fixed portion by a magnetic field generated at a time of energization of the electromagnet, and that perform a vibrating motion moving away from the fixed portion by biasing forces at a time of de-energization of the electromagnet, the biasing forces being generated during attraction; a flow channel through which a fluid flows; pump chambers disposed in the flow channel, the pump chambers being configured to suck and discharge the fluid in conjunction with a motion of the movable portions; a cooling flow channel disposed in a portion of the flow channel; and a heat-absorbing member that is cooled by the fluid flowing through the cooling flow channel and absorbs heat from a coil or a core of the electromagnet. EFFECTS OF THE INVENTION

[0007] According to the present disclosure, a pump and a beverage supply apparatus capable of suppressing performance degradation caused by heat generation of a drive source can be provided.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] [FIG. 1] FIG. 1 is a perspective view illustrating an example of an appearance of a pump according to an embodiment. [FIG. 2] FIG. 2 is a schematic view illustrating a schematic configuration inside a housing of the pump illustrated in FIG. 1. [FIG. 3] FIG. 3 is a perspective view illustrating a schematic configuration of a resonant actuator. [FIG. 4] FIG. 4 is an exploded perspective view illustrating the resonant actuator illustrated in FIG. 3. [FIG. 5] FIG. 5 is a schematic view illustrating a cross-sectional shape of the pump according to the embodiment along a symmetry axis CA. [FIG. 6] FIG. 6 is a schematic view illustrating a cross-sectional shape of the pump according to the embodiment along an axial direction of a fourth flow channel. [FIG. 7] FIG. 7 is a schematic view illustrating an operation of the pump when a coil is energized. [FIG. 8] FIG. 8 is a schematic view illustrating a periphery of a first pump chamber in a state illustrated in FIG. 7. [FIG. 9] FIG. 9 is a schematic view illustrating an operation of the pump when the coil is switched to a de-energized state. [FIG. 10] FIG. 10 is a schematic view illustrating a periphery of the first pump chamber in a state illustrated in FIG. 9. [FIG. 11] FIG. 11 is a schematic view illustrating a magnetic field generated in an electromagnet in which a flat core is used, as a comparative example. [FIG. 12] FIG. 12 is a plan view illustrating an internal structure of the housing of the pump as viewed from a positive Z-axis direction. [FIG. 13] FIG. 13 is a diagram illustrating an application example of the pump according to the embodiment. [FIG. 14] FIG. 14 is a diagram illustrating a configuration of a flow channel of a pump according to a first modification. [FIG. 15] FIG. 15 is a side view illustrating an exemplary configuration of a cooling flow channel and heat-absorbing members illustrated in FIG. 14. [FIG. 16] FIG. 16 is a diagram illustrating a configuration of a flow channel of a pump according to a second modification. [FIG. 17] FIG. 17 is a diagram illustrating a configuration of a flow channel of a pump according to a third modification. [FIG. 18] FIG. 18 is a schematic view illustrating a cross-sectional shape of a pump according to a fourth modification along a symmetry axis CA. [FIG. 19] FIG. 19 is a diagram illustrating a configuration of a flow channel of a pump according to a fifth modification. [FIG. 20] FIG. 20 is a diagram illustrating a configuration of a flow channel of a pump according to a sixth modification. [FIG. 21] FIG. 21 is a diagram illustrating an example of a configuration in which a coil cooling structure is applied to a pump according to the sixth modification. [FIG. 22] FIG. 22 is a schematic view illustrating a cross-sectional shape of a pump according to a seventh modification along a symmetry axis CA. MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same reference numerals are assigned to the same components throughout the drawings wherever possible, and duplicate descriptions are omitted.

[0010] In the following description, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X- and Y-axis directions are horizontal, and the Z-axis direction is vertical. The X-axis direction corresponds to the longitudinal direction of the housing 2 and the resonant actuator 6, and the Y-axis direction corresponds to the lateral direction of the housing 2 and the resonant actuator 6. For convenience of explanation, the positive Z-axis direction is sometimes referred to as the upper side, and the negative Z-axis direction as the lower side.[Pump Configuration]

[0011] The configuration of a pump 1 according to an embodiment will be illustrated with reference to FIGS. 1 to 6.

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

[0013] The housing 2 incorporates elements related to the pump function, such as a flow channel 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 a rectangular parallelepiped shape in which respective dimensions between the main surfaces 21 and 22 are relatively small compared to sides of the main surfaces.

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

[0015] Between the pair of main surfaces 21 and 22, four side surfaces 23 to 26 are disposed to connect the respective sides of the main surfaces 21 and 22. Of the four side surfaces, one pair of side surfaces 23 and 24 are formed in the same rectangular shape and are disposed to face each other in the X-axis direction, with their respective long sides connected to the short sides of the pair of main surfaces 21 and 22. The other pair of side surfaces 25 and 26 are also formed in the same rectangular shape and are disposed to face each other in the Y-axis direction, with their respective long sides connected to the long sides of the pair of main surfaces 21 and 22.

[0016] The inlet 3 sucks fluid into the housing 2, and the outlet 4 discharges fluid that has been pressurized by a pump function inside the housing 2. In the example illustrated in FIG. 1, the inlet 3 is disposed on a portion of the side surface 23 of the housing 2 on the negative Y-axis direction side, and the outlet 4 is disposed on a portion of the side surface 24 on the positive Y-axis direction side. The inlet 3 and the outlet 4 are in communication in the X-axis direction, and are disposed such that the direction in which fluid is sucked into the housing 2 through the inlet 3 and the direction in which fluid is discharged from the housing 2 through the outlet 4 are the same direction. Further, the inlet 3 and the outlet 4 are disposed so as to be point-symmetric with respect to the center line CO of the pump 1 when viewed from the Z-axis direction.

[0017] FIG. 2 is a schematic diagram illustrating the schematic structure inside the housing 2 of the pump 1 illustrated in FIG. 1. FIG. 2 is a plan view illustrating the pump 1 as viewed from the positive Z-axis direction side. In FIG. 2, the internal structure of the housing 2 is schematically illustrated, and the outer shape (i.e., the four side surfaces 23 to 26) of the housing 2 is indicated by two-dot chain lines. In FIG. 2, the symmetry axis CA, which passes through the center of the main surfaces 21 and 22 of the housing 2 in the Y-axis direction and extends in the X-axis direction, and the symmetry axis CB, which passes through the center in the X-axis direction and extends in the Y-axis direction, are indicated by one-dot chain lines. The intersection of the symmetry axes CA and CB is illustrated as the center line CO.

[0018] As illustrated in FIG. 2, the pump 1 includes a flow channel 5 that connects the inlet 3 and the outlet 4 inside the housing 2. The flow channel 5 includes a first flow channel 51, a second flow channel 52, a third flow channel 53, a fourth flow channel 54, a fifth flow channel 55, a sixth flow channel 56, a seventh flow channel 57, and an eighth flow channel 58.

[0019] The first flow channel 51 is disposed such that its upstream end is connected to the downstream end of the inlet 3 and extends in the positive X-axis direction. The second flow channel 52 and the third flow channel 53 branch from the downstream end of the first flow channel 51, extending in the negative X-axis direction and the positive X-axis direction, respectively. The fourth flow channel 54 is disposed such that its upstream end is connected to the downstream end of the second flow channel 52 and extends in the positive Y-axis direction. The fifth flow channel 55 is disposed such that its upstream end is connected to the downstream end of the third flow channel 53 and extends in the positive Y-axis direction. The sixth flow channel 56 is disposed such that its upstream end is connected to the downstream end of the fourth flow channel 54 and extends in the positive X-axis direction, and the seventh flow channel 57 is disposed such that its upstream end is connected to the downstream end of the fifth flow channel 55, extends in the negative X-axis direction, and merges with the sixth flow channel 56 at their downstream ends. The eighth flow channel 58 is disposed such that its upstream end is connected to the merging portion of the sixth flow channel 56 and the seventh flow channel 57, extends in the positive X-axis direction, and has its downstream end connected to the upstream end of the outlet 4. In FIG. 2, the flow directions of the fluid flowing through the inlet 3, the flow channel 5, and the outlet 4 are illustrated by arrows.

[0020] As described above with reference to FIG. 1, the inlet 3 and the outlet 4 are disposed to be point-symmetric with respect to the center line CO of the pump 1 when viewed from the Z-axis direction. Accordingly, the overall shape of the flow channel 5 is also preferably disposed to be point-symmetric with respect to the center line CO of the pump 1 when viewed from the Z-axis direction. This arrangement allows fluid to flow more easily from the inlet 3 to the outlet 4 via the flow channel 5.

[0021] In addition, a resonant actuator 6 is installed inside the housing 2 as a driving source for the pump 1. The resonant actuator 6 includes an electromagnet 61 and is a device that generates a vibrating motion by switching an energized state and a de-energized state of the electromagnet 61. The resonant actuator 6 brings movable portions, which serve as vibrating elements (a group of components including movable plates 62 and 63, leaf springs 64 and 65, and the like to be described later), into a resonant state by setting a frequency of a control signal for switching between the energized and de-energized states (i.e., a switching frequency) to be equal to, or in the vicinity of, a resonant frequency of the movable portion. Accordingly, the resonant actuator 6 can efficiently vibrate the movable portions by utilizing the resonance of the movable portions in addition to attracting the movable portions by the electromagnet 61 when the electromagnet 61 is energized.

[0022] In the example of FIG. 2, the resonant actuator 6 is arranged such that the X direction serves as a longitudinal direction and the Y direction serves as a short-side direction, and is located at a central position in a view along the Z direction. The resonant actuator 6 is also formed, like the housing 2, to be line-symmetric in the Y direction with respect to the symmetry axis CA, and line-symmetric in the X direction with respect to the symmetry axis CB. The electromagnet 61 is located at the center of the resonant actuator 6.

[0023] The fourth flow channel 54 of the flow channel 5 is disposed adjacent to the electromagnet 61 on the X-negative side and extends through the resonant actuator 6 in the Y-axis direction. Similarly, the fifth flow channel 55 of the flow channel 5 is disposed adjacent to the electromagnet 61 on the X-positive side and extends through the resonant actuator 6 in the Y-axis direction.

[0024] A first pump chamber 7 and a second pump chamber 8 are disposed in the portions of the fourth flow channel 54 and the fifth flow channel 55, respectively, that overlap the resonant actuator 6 when viewed from the Z-axis direction. The first pump chamber 7 and the second pump chamber 8 are components that pressurize and deliver fluid from the upstream side to the downstream side of the flow channel 5 in conjunction with the vibratory motion of the resonant actuator 6. The fluid in the flow channel 5 can flow from the inlet 3 to the outlet 4 through 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 positioned on the symmetry axis CA of the housing 2 and the resonant actuator 6. Further, as described above, in the example of FIG. 2, the shape of the flow channel 5 is disposed to be point-symmetric in the Z-axis direction view with respect to the central axis O passing through the centers of the pair of main surfaces 21 and 22 of the housing 2. Thus, since the first pump chamber 7 and the second pump chamber 8 are respectively disposed at a substantially middle position along the flow channel 5, the energy required for suction of fluid into the first pump chamber 7 and the second pump chamber 8, and the energy required for discharge of fluid from the first pump chamber 7 and the second pump chamber 8 can be substantially the same.

[0025] The configuration of the resonant actuator 6 of the pump 1 according to the embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a perspective view illustrating the schematic structure of the resonant actuator 6. FIG. 4 is an exploded perspective view of the resonant actuator 6 illustrated in FIG. 3. The perspective directions of FIGS. 3 and 4 are the same as those of FIG. 1.

[0026] As illustrated 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-axis direction. As illustrated in FIG. 4, the electromagnet 61 includes a core 611 and a coil 612. The core 611 includes a winding portion 611A and a pair of widening portions 611B. The winding portion 611A is a central portion of the core 611 in the X-axis direction and is formed to extend in the X-axis direction. The winding portion 611A has a rectangular cross-section along a YZ plane, and outer peripheral surfaces are formed by four surfaces whose normal directions are a positive Y-axis direction, a negative Y-axis direction, a positive Z-axis direction, and a negative Z-axis direction. The coil 612 is wound around the outer peripheral surfaces of the winding portion 611A. A pair of widening portions 611B are formed at both ends of the winding portion 611A along the X-axis direction and formed to protrude toward both sides in the Z-axis direction relative to the winding portion 611A. The widening portions 611B each also have a rectangular cross-sectional shape along the YZ plane, and have four surfaces with the positive Y-axis direction side, the negative Y-axis direction side, the positive Z-axis direction side, and the negative Z-axis direction side as the normal directions. That is, the widening portions 611B have an upper end surface and a lower end surface formed so as to protrude from the winding portion 611A by the same amount along the Y-axis direction.

[0028] The electromagnet 61 generates a magnetic field passing through the center of the coil 612 when current flows through the conductor constituting the coil 612, upon energization of the coil 612. The magnetic field generated by the coil 612 is further intensified by the core 611.

[0029] The pair of movable plates 62 and 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 Z-positive side of the electromagnet 61, and the second movable plate 63 is disposed on the Z-negative 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 facing each other in the Z-axis direction.

[0030] Since the first movable plate 62 and the second movable plate 63 are made of a magnetic material, the first movable plate 62 and the second movable plate 63 are attracted to the electromagnet 61 by a magnetic field generated when the electromagnet 61 is energized. When the electromagnet 61 switches from the energized state to the de-energized state, the first movable plate 62 and the second movable plate 63 move in the direction opposite to the attraction motion by biasing forces applied from the leaf springs 64 and 65 to which the first movable plate 62 and the second movable plate 63 are attached, respectively. In other words, the first movable plate 62 and the second movable plate 63 can perform a vibratory motion in the Z direction by switching the electromagnet 61 between the energized and de-energized states.

[0031] As illustrated in FIG. 4, the first movable plate 62 includes a central portion 621 and a pair of end portions 622 and 623. The central portion 621 is a portion at the center of the first movable plate 62 in the X-axis direction, and is formed in a rectangular shape with its long sides facing the Y-axis direction and its short sides facing the X-axis direction when viewed in the Z-axis direction. The shape of the central portion 621 is formed so as to cover the entire outer profile of the electromagnet 61 when viewed from the Z-positive side. The pair of end portions 622 and 623 are disposed so as to be connected to both ends of the central portion 621 along the X-axis direction, that is, to the short sides of the above-described rectangular shape. In the example illustrated in FIG. 4, one end portion 622 is disposed on the X-negative side of the central portion 621, and the other end portion 623 is disposed on the X-positive side of the central portion 621. The dimension of the pair of end portions 622 and 623 in the Y-axis direction is the same as that of the central portion 621. The X-axis direction dimensions of the pair of end portions 622 and 623 are substantially the same. Further, the thickness of the pair of end portions 622 and 623 in the Z-axis direction is preferably formed thinner than that of the central portion 621, as exemplified in FIGS. 3 and 4.

[0032] The pair of end portions 622 and 623 of the first movable plate 62 are provided with pistons 71 and 81 so as to extend in the negative Z-axis direction on the surfaces of the respective negative Z-axis direction sides. 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 and 633. The central portion 631 is a portion at the center of the second movable plate 63 in the X-axis direction, and is formed in a rectangular shape with the long sides facing the Y-axis direction and the short sides facing the X-axis direction when viewed in the Z-axis direction. The shape of the central portion 631 is formed so as to cover the entire outer profile of the electromagnet 61 when viewed from the negative Z-axis direction side. The pair of end portions 632 and 633 are disposed so as to be connected to both ends of the central portion 631 along the X-axis direction, that is, to the short sides of the above-described rectangular shape. In the example illustrated in FIG. 4, one end portion 632 is disposed on the negative X-axis direction side of the central portion 621, and the other end portion 633 is disposed on the positive X-axis direction side of the central portion 631. The dimension of the pair of end portions 632 and 633 in the Y-axis direction is the same as that of the central portion 631. The dimensions of the pair of end portions 632 and 633 in the X-axis direction are substantially the same. The thickness of the pair of end portions 632 and 633 in the Z-axis direction is preferably thinner than the central portion 631, as illustrated in FIGS. 3 and 4, for example.

[0034] The pair of end portions 632 and 633 of the second movable plate 63 are provided with pistons 72 and 82 extending in the positive Z-axis direction on their respective faces in the positive Z-axis direction. The pistons 72 and 82 will be described later.

[0035] The pair of leaf springs 64 and 65 are elastic members that bias in the Z-axis direction, and include a first leaf spring 64 and a second leaf spring 65. The first leaf spring 64 is disposed on the positive Z-axis direction side from 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 negative Z-axis direction side from the second movable plate 63, and the second movable plate 63 is attached to the second leaf spring 65. The first leaf spring 64 and the second leaf spring 65 are formed in the same shape and are disposed to face each other in the Z-axis direction. That is, as illustrated in FIG. 3, the first leaf spring 64 and the second leaf spring 65 constitute the outermost portion of the resonant actuator 6 in the Z-axis direction. The first leaf spring 64 biases the first movable plate 62 in a direction opposite to the attraction motion (toward the positive Z-axis direction) in accordance with the attraction motion of the first movable plate 62 toward the electromagnet 61. Similarly, the second leaf spring 65 biases the second movable plate 63 in a direction opposite to the attraction motion (toward the negative Z-axis direction) in accordance with the attraction motion of the second movable plate 63 toward the electromagnet 61.

[0036] As illustrated in FIG. 4, the first leaf spring 64 has a central portion 641, a pair of fixed end portions 642, and a pair of bent portions 643. The central portion 641 is a portion at the center of the first leaf spring 64 in the X-axis direction, and is a flat plate portion formed such that the width dimension in the Y-axis direction is constant and the outer edge ends on both sides in the Y-axis direction extend along the X-axis direction. The first leaf spring 64 is installed so as to be movable integrally with the first movable plate 62 by mounting the first movable plate 62 to the central portion 641.

[0037] The pair of fixed end portions 642 are disposed at both ends of the first leaf spring 64 along the X-axis direction, and are flat plate portions formed such that both outer edge ends in the X-axis direction extend along the Y-axis direction. The pair of fixed end portions 642 of the first leaf spring 64 are fixed to a support 9 (see FIG. 5 or the like) as an example of a fixed object installed inside the housing 2, and thus both end portions in the X-axis direction are fixed.

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

[0039] Further, as illustrated in FIG. 4 or the like, the pair of bent portions 643 are formed such that the width perpendicular to the direction in which the central portion 641 and the pair of fixed end portions 642 are connected is relatively small so as to be elastically deformed, and are formed so as to be curved in an S-shape when viewed in the Z-axis direction. Further, in order to further equalize the bent amount in the Y-axis direction, S-shaped curved portions are disposed on both sides in the Y-axis direction across the symmetry axis CA, and are formed so as to be linearly symmetric with respect to the symmetry axis CA. Note that the curved portions may have a shape other than an S-shape.

[0040] As illustrated in FIG. 4, the second leaf spring 65 has a central portion 651, a pair of fixed end portions 652, and a pair of bent portions 653. The central portion 651 is a portion at the center of the second leaf spring 65 in the X-axis direction, and is a flat plate portion formed such that the width in the Y-axis direction is constant and the outer edge ends on both sides in the Y-axis direction extend along the X-axis direction. The second leaf spring 65 is provided with a second movable plate 63 attached to the central portion 651 so as to be movable integrally with the second movable plate 63.

[0041] The pair of fixed end portions 652 are disposed at both ends of the second leaf spring 65 along the X-axis direction, and are flat plate portions formed such that both outer edge ends in the X-axis direction extend along the Y-axis direction. The pair of fixed end portions 652 of the second leaf spring 65 are fixed to the support 9 (see FIG. 5 or the like) as an example of a fixed object installed inside the housing 2, and thus both end portions in the X-axis direction are fixed.

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

[0043] Further, as illustrated in FIG. 4 and the like, the pair of bent portions 653 are formed with a relatively small width dimension perpendicular to the direction connecting the central portion 651 and the pair of fixed end portions 652, so as to allow elastic deformation more easily, and are formed to be curved in an S-shape when viewed in the Z-axis direction. In addition, to make the bent amounts in the Y-axis direction more uniform, the S-shaped curved portions are disposed on both sides in the Y-axis direction across the symmetry axis CA and are formed to be line-symmetric with respect to the symmetry axis CA. Note that the curved portions may have shapes other than the S-shape.

[0044] Further, as illustrated in FIG. 4, each component of the resonant actuator 6 is disposed such that the center position of its outer shape when viewed in the Z-axis direction coincides with the center line CO of the pump 1. As a result, the center of gravity of the resonant actuator 6 can be located near the center line CO of the pump 1, thereby allowing the resonant actuator 6 to operate in a well-balanced manner.

[0045] It should be noted that although, in the present embodiment, a configuration in which the first movable plate 62 and the second movable plate 63 are respectively attached to central portions 641 and 651 of the first leaf spring 64 and the second leaf spring 65 is described, the first movable plate 62 and the second movable plate 63 may be attached to any positions other than the central portions in the X-axis direction of the first leaf spring 64 and the second leaf spring 65, respectively. In addition, although the first leaf spring 64 and the second leaf spring 65 are each fixed to the support 9 at the pair of fixed end portions 642 and the pair of fixed end portions 652, the first leaf spring 64 and the second leaf spring 65 may be fixed to the support 9 at any positions other than the both ends in the X-axis direction.

[0046] In the present embodiment, as described above, the first movable plate 62 and the second movable plate 63 are formed in the same shape, and the first leaf spring 64 and the second leaf spring 65 are formed in the same shape. The attached position of the first movable plate 62 to the first leaf spring 64 and the attached position of the second movable plate 63 to the second leaf spring 65 are also the same. Therefore, the resonance frequency of the first movable portion (the first movable plate 62 and the first leaf spring 64) and the resonance frequency of the second movable portion (the second movable plate 63 and the second leaf spring 65) are the same. Thus, when the switching frequency for alternating the energized and de-energized states of the single electromagnet 61 disposed between the first movable portion and the second movable portion is set to a frequency equal to or close to the common resonance frequency of the first and second movable portions, both movable portions can be brought into resonance simultaneously. Consequently, the resonant actuator 6 of the present embodiment can vibrate the movable portions more efficiently.

[0047] The configurations of the first pump chamber 7 and the second pump chamber 8 of the pump 1 according to the embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic view illustrating a cross-sectional shape of the pump 1 according to the embodiment along the symmetry axis CA. In FIG. 5, elements outside the resonant actuator 6, including the housing 2, of the components of the pump 1 are not illustrated.

[0048] As illustrated in FIG. 5, the fourth flow channel 54 and the fifth flow channel 55 are holes provided in the support 9 as an example of a fixed object installed inside the housing 2. The support 9 includes, for example, a block-shaped component fixed to an inner wall surface of the housing 2. Other channels of the flow channel 5 other than the fourth flow channel 54 and the fifth flow channel 55 are also holes provided in the support 9. It should be noted that in the example illustrated in FIG. 5, the support 9 provided with the flow channel 5 and the support 9 to which the pair of fixed end portions 642 of the first leaf spring 64 and the pair of fixed end portions 652 of the second leaf spring 65 of the resonant actuator 6 are fixed are illustrated as an integral component. However, other components may be integrally connected as an integral component. Similarly, the first to eighth flow channels 51 to 58 constituting the flow channel 5 may be provided in the separate supports, and these supports may be connected to form the flow channel 5.

[0049] Since the cross section illustrated in FIG. 5 is a cross section along the symmetry axis CA of the pump 1, it is a cross section of a portion of the fourth flow channel 54 in which the first pump chamber 7 is disposed and a portion of the fifth flow channel 55 in which the second pump chamber 8 is disposed, as is apparent with reference to FIG. 2. As illustrated in FIG. 5, the first pump chamber 7 and the second pump chamber 8 are provided with cylinders 73 and 83 communicating along the Z-axis direction, respectively.

[0050] The cylinder 73 of the first pump chamber 7 is formed so as to open on the positive Z-axis direction side and the negative Z-axis direction side of the support 9. Further, in the present embodiment, the first piston 71 disposed on the first movable plate 62 and the second piston 72 disposed on the second movable plate 63 are disposed at positions where the axial direction overlaps the first pump chamber 7, that is, overlaps the axial direction of the cylinder 73. Therefore, as illustrated in FIG. 5, the first piston 71 is slidably inserted into the cylinder 73 through an opening on the positive Z-axis direction side, and the second piston 72 is slidably inserted into the cylinder 73 through an opening on the negative Z-axis direction side.

[0051] The cylinder 83 of the second pump chamber 8 is formed to open on the positive Z-axis direction side and the negative Z-axis direction side of the support 9. Further, in the present embodiment, the first piston 81 disposed on the first movable plate 62 and the second piston 82 disposed on the second movable plate 63 are disposed at positions where the axial direction overlaps the second pump chamber 8, that is, overlaps the axial direction of the cylinder 83. Therefore, as illustrated in FIG. 5, the first piston 81 is slidably inserted into the cylinder 83 through an opening on the positive Z-axis direction side, and the second piston 82 is slidably inserted into the cylinder 83 through an opening on the negative Z-axis direction side.

[0052] These first pistons 71 and 81 and the second pistons 72 and 82 are disposed in the first movable plate 62 and the second movable plate 63, respectively. Therefore, the first pistons 71 and 81 and the second pistons 72 and 82 slide within the respective cylinders 73 and 83 in conjunction with the vibratory motion of the first movable plate 62 and the second movable plate 63 in the Z-axis direction by the energization control of the electromagnet 61, and repeatedly approach and move away from each other. Thus, the volumes of the first pump chamber 7 and the second pump chamber 8 can be increased or decreased.

[0053] FIG. 6 is a schematic view illustrating a cross-sectional shape of the fourth flow channel 54 of the pump 1 according to an embodiment along the axial direction. As illustrated in FIG. 6, a suction valve 74 and a discharge valve 75 are disposed on the upstream and downstream sides of the first pump chamber 7 in the fourth flow channel 54, respectively.

[0054] When the first piston 71 and the second piston 72 approach each other in the cylinder 73, causing the volume of the first pump chamber 7 to decrease, the suction valve 74 is configured to close, thereby preventing fluid from flowing from the upstream side of the fourth flow channel 54 into the first pump chamber 7. At the same time, the discharge valve 75 is configured to open, allowing fluid to flow from the first pump chamber 7 to the downstream side of the fourth flow channel 54. Conversely, when the first piston 71 and the second piston 72 recede from each other in the cylinder 73, causing the volume of the first pump chamber 7 to increase, the suction valve 74 is configured to open, allowing fluid to flow from the upstream side of the fourth flow channel 54 into the first pump chamber 7. Meanwhile, the discharge valve 75 is configured to close, thereby stopping the discharge of fluid from the first pump chamber 7 to the downstream side of the fourth flow channel 54.

[0055] FIG. 6 illustrates an example of a configuration for realizing such an operation, in which both the suction valve 74 and the discharge valve 75 include a ball disposed on the upstream side of the fourth flow channel 54 so as to seal the flow channel, and a spring disposed on the downstream side to urge the ball toward the upstream side. However, a configuration other than that illustrated in FIG. 6 may be applied to the suction valve 74 and the discharge valve 75.

[0056] In the present embodiment, the volume of the first pump chamber 7 is defined as a region between the lower end surface of the first piston 71 and the upper end surface of the second piston 72 in the cylinder 73. The volume varies according to the vertical movement (reciprocation) of the first piston 71 and the second piston 72 within the cylinder 73.

[0057] Although the configuration of the first pump chamber 7 is described with reference to FIG. 6, which illustrates the cross section of the fourth flow channel 54, the configuration of the second pump chamber 8 in the fifth flow channel 55 is similar. That is, the volume of the second pump chamber 8 is defined as a region between the lower end surface of the first piston 81 and the upper end surface of the second piston 82 in the cylinder 83. The volume varies according to the vertical movement (reciprocation) of the first piston 81 and the second piston 82 within the cylinder 83.[Operation of Pump]

[0058] The operation of the pump 1 according to the embodiment will be described with reference to FIGS. 7 to 10.

[0059] FIG. 7 is a schematic diagram illustrating the operation of the pump 1 when the coil is energized. FIG. 8 is a schematic diagram illustrating the vicinity of the first pump chamber 7 in the state of FIG. 7. The outlines of FIGS. 7 and 8 are similar to those of FIGS. 5 and 6.

[0060] As illustrated in FIG. 7, when the coil 612 of the electromagnet 61 is energized, a magnetic field M1 passing through the center of the coil 612 is generated. The magnetic field M1 generated by the coil 612 is further intensified by a winding portion 611A of the core 611, which penetrates the center of the coil 612. In the example illustrated in FIG. 7, the magnetic field M1 is directed toward the positive X-axis direction inside the winding portion 611A.

[0061] The magnetic field M1 generated in this manner branches into the positive Z-axis direction and the negative Z-axis direction along the protruding direction of one widening portion 611B, which is disposed on the positive X-axis direction side of the winding portion 611A of the core 611. Next, the magnetic field flows into the interiors of the first movable plate 62 and the second movable plate 63, which are disposed to face the upper and lower end surfaces of the widening portion 611B, respectively, toward the negative X-axis direction. Then, from the upper and lower end surfaces of the other widening portion 611B disposed on the negative X-axis direction side of the winding portion 611A, the magnetic field flows into the interior of this widening portion 611B toward a central portion in the Z-axis direction, merges, and then flows again into the winding portion 611A. That is, when the magnetic field M1 illustrated in FIG. 7 is viewed from the negative Y-axis direction, the flow becomes clockwise on the side of the first movable plate 62, and counterclockwise on the side of the second movable plate 63.

[0062] By the generation of such a magnetic field M1, the first movable plate 62 is attracted by the electromagnet 61 and moves toward the negative Z-axis direction side as illustrated by an arrow A in FIG. 7. Similarly, the second movable plate 63 is attracted by the electromagnet 61 and moves toward the positive Z-axis direction side as illustrated by an arrow B.

[0063] By such movement of the first movable plate 62 and the second movable plate 63 toward the side attracted by the electromagnet 61, the first piston 71 slides within the cylinder 73 toward the negative Z-axis direction side as illustrated by an arrow C in the first pump chamber 7. The second piston 72 slides within the cylinder 73 toward the positive Z-axis direction side as illustrated by an arrow D. Thus, the lower end surface of the first piston 71 and the upper end surface of the second piston 72 move closer to each other, thereby reducing the volume of the first pump chamber 7.

[0064] Similarly, the first piston 81 slides within the cylinder 83 toward the negative Z-axis direction as illustrated by an arrow E in the second pump chamber 8. Further, as illustrated by an arrow F, the second piston 82 slides within the cylinder 83 toward the positive Z-axis direction. Thus, the lower end surface of the first piston 81 and the upper end surface of the second piston 82 move closer to each other, thereby reducing the volume of the second pump chamber 8.

[0065] Here, ideally, both the first movable plate 62 and the second movable plate 63 are moved in parallel in the Z-axis direction by the magnetic field M1. Therefore, the sliding amounts of the two first pistons 71 and 81 installed on the first movable plate 62 and the sliding amounts of the two second pistons 72 and 82 installed on the second movable plate 63 are the same. Therefore, the reduction amounts of the volumes of the first pump chamber 7 and the second pump chamber 8 are also the same.

[0066] In addition, due to the movement of the first movable plate 62 toward the side to be attracted by 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 the arrow A. At this time, since the fixed end portions 642 of the first leaf spring 64 are each fixed to the support 9, the central portion 641 is displaced in the negative Z-axis direction with respect to each of the fixed end portions 642. In FIG. 7, the position of the first leaf spring 64 in the steady state illustrated in FIG. 5 in the Z-axis direction is illustrated by a dotted line S1. As a result of this displacement, the bent portion 643 disposed between the central portion 641 and each of the fixed end portions 642 is elastically deformed in the negative Z-axis direction, thereby generating biasing forces f1 for elastically returning the respective bent portions 643 to the positive Z-axis direction, as illustrated by the dotted arrows for the biasing forces f1 in FIG. 7.

[0067] Similarly, the central portion 651 of the second leaf spring 65 to which the second movable plate 63 is attached also moves in the direction of the arrow B integrally with the second movable plate 63 due to the movement of the second movable plate 63 toward the side to be attracted by the electromagnet 61. At this time, since the fixed end portions 652 of the second leaf spring 65 are each fixed to the support 9, the central portion 651 is displaced relative to each of the fixed end portions 652 in the positive Z-axis direction. In FIG. 7, the position of the second leaf spring 65 in the steady state illustrated in FIG. 5 in the Z-axis direction is illustrated by a dotted line S2. As a result of this displacement, the bent portion 653 disposed between the central portion 651 and each of the fixed end portions 652 is elastically deformed in the positive Z-axis direction, thereby generating biasing forces f2 for elastically returning the respective bent portions 653 to the negative Z-axis direction, as illustrated by the dotted arrows for the biasing forces f2 in FIG. 7.

[0068] When the first pistons 71 and 81 and the second pistons 72 and 82 as illustrated in FIG. 7 approach each other, the volumes of the first pump chamber 7 and the second pump chamber 8 are decreased. Consequently, as illustrated in FIG. 8, in the first pump chamber 7, the balls of the suction valve 74 and the discharge valve 75 are pressed to the upstream side and the downstream side of the fourth flow channel 54, respectively, by the fluid in the first pump chamber 7. At this time, since the ball of the suction valve 74 blocks the upstream side of the fourth flow channel 54, the suction valve 74 is closed. On the other hand, since the ball of the discharge valve 75 is movable downstream as indicated by the arrow G, 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 channel 54.

[0069] As described above, since the amount of volume reduction of the first pump chamber 7 and the second pump chamber 8 is also the same, the fluid in the second pump chamber 8 is pressurized in the same manner as the operation of the first pump chamber 7 illustrated in FIG. 7, and is discharged to the downstream side of the fifth flow channel 55.

[0070] FIG. 9 is a schematic view illustrating the operation of the pump 1 when the coil is switched to the de-energized state after the energization of the coil illustrated in FIG. 7. FIG. 10 is a schematic view illustrating the periphery of the first pump chamber 7 in the state illustrated in FIG. 9. The outline of FIGS. 9 and 10 is the same as that of FIGS. 5 and 6.

[0071] As illustrated in FIG. 9, when the coil 612 of the electromagnet 61 is switched from the energized state illustrated in FIG. 7 to the de-energized state, the magnetic field M1 generated around the electromagnet 61 disappears.

[0072] As the magnetic field M1 disappears, the attractive force received by the first movable plate 62 and the second movable plate 63 from the electromagnet 61 also disappears. Therefore, as indicated by the dotted arrow in FIG. 7, the biasing force f1 generated in the bent portion 643 of the first leaf spring 64 causes the first leaf spring 64 to elastically return, and the first movable plate 62 also moves toward the positive Z-axis direction in accordance with this movement. However, as the attractive force balanced with the biasing force f1 disappears, the first movable plate 62 and the first leaf spring 64 do not stand still at the stationary position S1, but move further toward the positive Z-axis direction. Finally, as indicated by an arrow H in FIG. 9, the electromagnet 61 moves toward the positive Z-axis direction from the stationary position S1 by an amount equal to the amount of movement due to attraction. Similarly, as indicated by an arrow I, the second movable plate 63 and the second leaf spring 65 also move toward the negative Z-axis direction from the stationary position S2 due to the biasing force f2 generated in the bent portion 653 toward the negative Z-axis direction.

[0073] As a result of such movement of the first movable plate 62 and the second movable plate 63 toward the side moving away from the electromagnet 61, the first piston 71 slides within the cylinder 73 toward the positive Z-axis direction as indicated by an arrow J in the first pump chamber 7. The second piston 72 slides within the cylinder 73 toward the negative Z-axis direction as indicated by an 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, thereby increasing the volume of the first pump chamber 7.

[0074] Similarly, in the second pump chamber 8, the first piston 81 slides within the cylinder 83 in the positive Z-axis direction as indicated by an arrow L. The second piston 82 slides within the cylinder 83 in the negative Z-axis direction as indicated by an 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, thereby increasing the volume of the second pump chamber 8.

[0075] Here, ideally, both the first movable plate 62 and the second movable plate 63 move in parallel in the Z-axis direction by the biasing forces f1 and f2 of the bent portions 643 and 653. Therefore, the sliding amounts of the two first pistons 71 and 81 installed on the first movable plate 62 and the sliding amounts of the two second pistons 72 and 82 installed on the second movable plate 63 are the same. Therefore, the amounts of increase in the volumes of the first pump chamber 7 and the second pump chamber 8 are also the same.

[0076] When a separation motion occurs between the first pistons 71 and 81 and the second pistons 72 and 82, as illustrated in FIG. 9, the volumes of the first pump chamber 7 and the second pump chamber 8 increase. Accordingly, as illustrated in FIG. 10, in the first pump chamber 7, the balls of the suction valve 74 and the discharge valve 75 are each sucked in toward the cylinder 73 by the fluid within the first pump chamber 7. At this time, the ball of the discharge valve 75 moves, as indicated by an arrow N, to close an upstream side of the fourth flow channel 54, thereby closing the discharge valve 75. Meanwhile, since the ball of the suction valve 74 is caused to move toward a downstream side, as indicated by an arrow O, the suction valve 74 opens. As a result, the fluid on the upstream side of the fourth flow channel 54 is drawn into the first pump chamber 7.

[0077] As described above, since the amount of volume increase of the first pump chamber 7 and the second pump chamber 8 is also the same, the fluid on the upstream side of the fifth flow channel 55 is drawn into the second pump chamber 8 in the same manner as the operation of the first pump chamber 7 illustrated in FIG. 10.

[0078] In the pump 1 of the present embodiment, the pump 1 can be driven by of the electromagnet 61 so as to repeat the state when the coil is energized (the first state) illustrated in FIGS. 7 and 8 and the state when the coil is not energized (the second state) illustrated in FIGS. 9 and 10.

[0079] In this control, the pressure of the fluid discharged from the pump 1 can be adjusted in accordance with the amounts and speeds of movement of the first pistons 71 and 81 and the second pistons 72 and 82. In order to adjust the pressure, it is necessary to adjust the amounts and speeds of movement of the first movable plate 62 and the second movable plate 63 on which the first pistons 71 and 81 and the second pistons 72 and 82 are installed. In order to adjust the movement of the movable plates 62 and 63, it is necessary to adjust the strength (e.g., magnetic flux density) 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 supplied to the coil 612 of the electromagnet 61. That is, in the pump 1 of the present embodiment, it is possible to control the discharge of fluid at a desired pressure by controlling the current supplied to the coil 612 of the resonant actuator 6.

[0080] Alternatively, the pump 1 of the present embodiment can be controlled to discharge fluid at a desired pressure by adjusting various structural parameters, such as, for example, the number of turns of the conductor wire of the coil 612 of the electromagnet 61, the dimensions of the winding portion 611A of the core 611 in the X-axis direction and the Y-axis direction, the amount of protrusion in the Z-axis direction and the dimensions of the widening portion 611B of the core 611 in the X-axis direction and the Y-axis direction, the area and shape of the first movable plate 62 and the second movable plate 63 in the Z-axis direction, and the spring constants of the first leaf spring 64 and the second leaf spring 65.

[0081] The pump 1 of the present 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 at a time of energization of the electromagnet 61; 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, the leaf springs being configured to bias the first movable plate 62 and the second movable plate 63 in a direction opposite to an attraction motion toward the electromagnet 61; a flow channel 5 through which a fluid flows; a first pump chamber 7 and a second pump chamber 8 disposed in the flow channel 5; first pistons 71 and 81 and second pistons 72 and 82 as examples of volume changing members configured to decrease volumes of the first pump chamber 7 and the second pump chamber 8 in accordance with the attraction motion of the first movable plate 62 and the second movable plate 63, and to increase the volumes of the first pump chamber 7 and the second pump chamber 8 when the electromagnet 61 is switched to a de-energized state after the attraction motion, in accordance with a separation motion of the first movable plate 62 and the second movable plate 63 moving away from the electromagnet 61 by biasing forces of the first leaf spring 64 and the second leaf spring 65; suction valves 74 disposed on an upstream side of the flow channel 5 in the first pump chamber 7 and the second pump chamber 8, the suction valves 74 being configured to open when the first pistons 71 and 81 and the second pistons 72 and 82 operate in a direction to increase the volumes of the first pump chamber 7 and the second pump chamber 8 to suck fluid from the upstream side of the flow channel 5 into the pump chambers; and discharge valves 75 disposed on a downstream side of the flow channel 5 in the first pump chamber 7 and the second pump chamber 8, the discharge valves 75 being configured to open when the first pistons 71 and 81 and the second pistons 72 and 82 operate in a direction to decrease the volumes of the first pump chamber 7 and the second pump chamber 8 to discharge the fluid from the first pump chamber 7 and the second pump chamber 8 to the downstream side of the flow channel 5.

[0082] Here, among the above-described components, the electromagnet 61 can also be referred to as a "fixed portion." In addition, the first movable plate 62 and the second movable plate 63, together with the first leaf spring 64 and the second leaf spring 65, can be described as "movable portions that are attracted toward the fixed portion by a magnetic field generated at a time of energization of the electromagnet 61, and that perform a vibrating motion moving away from the fixed portion by biasing forces of the movable portions, the biasing forces being generated during attraction and acting upon de-energization of the electromagnet 61."

[0083] With the above configuration, the vibrating motion generated in the movable portions (the first movable plate 62 and the second movable plate 63, and the first leaf spring 64 and the second leaf spring 65) by the fixed portion (electromagnet 61) allows the first piston 71 and the second piston 72, provided in the first pump chamber 7, to slide synchronously within a common cylinder 73. In other words, the resonant actuator 6 can be used as a driving source for the pump 1. This configuration enables a reduction in the movement amounts of the pistons for varying the volumes of the first and second pump chambers 7 and 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 be equal to or close to the resonant frequency of the movable portions, which serve as the vibrating elements, the movable portions can be caused to resonate. As a result, the resonant actuator 6 can efficiently vibrate the movable portions by utilizing both the attraction of the movable portions toward the electromagnet 61 upon energization and the resonance of the movable portions. Consequently, the pump 1 of the present embodiment can operate with high efficiency.

[0084] In the pump 1 of the present embodiment, the first movable plate 62 and the second movable plate 63 are disposed to face each other across the electromagnet 61. 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. In other words, the first leaf spring 64 and the second leaf spring 65 are also disposed to face each other across the electromagnet 61. The first pistons 71 and 81 are disposed on the first movable plate 62 and operate in conjunction with the motion of the first movable plate 62. The second pistons 72 and 82 are disposed on the second movable plate 63 and operate in conjunction with the motion of the second movable plate 63.

[0085] With this configuration, a single electromagnet 61 can cause a pair of facing movable portions (the first movable plate 62 and the first leaf spring 64, and the second movable plate 63 and the second leaf spring 65) to vibrate synchronously. Since the pair of movable portions are disposed to face each other across the electromagnet 61, directions in which they are attracted toward the electromagnet 61 are opposite to each other. Therefore, vibrating directions of the pair of movable portions are in opposite phases. As a result, vibrations generated in the pump 1 by motions of the respective movable portions can be offset and canceled.

[0086] In the pump 1 of the present embodiment, the first movable portion (the first movable plate 62 and the first leaf spring 64) and the second movable portion (the second movable plate 63 and the second leaf spring 65) are disposed to face each other across the fixed portion (electromagnet 61). The first pistons 71 and 81 operate in conjunction with the motion of the first movable portion, and the second pistons 72 and 82 operate in conjunction with the motion of the second movable portion. The first piston 71 and the second piston 72 are provided in the same first pump chamber 7. Similarly, the first piston 81 and the second piston 82 are provided in the same second pump chamber 8.

[0087] With this configuration, since a pump chamber in which a pair of pistons are provided is shared, only one flow channel (fourth flow channel 54) and one set of valves (suction valve 74 and discharge valve 75) are required for a pair of the first piston 71 and the second piston 72. Similarly, only one flow channel (fifth flow channel 55) and one set of valves (suction valve 74 and discharge valve 75) are required for a pair of the first piston 81 and the second piston 82. As a result, the number of components can be decreased, and the structure of the pump 1 can be simplified. Furthermore, since the pump chamber is shared, the reaction forces acting on the pair of pistons provided in the pump chamber are equal, which decreases the deviation between the motions of the pair of facing movable portions. Consequently, it is possible to increase the number of pump chambers and improve pump efficiency while reducing the number of components.

[0088] Here, with reference to FIG. 11 in addition to FIG. 7, the effect of the core 611 of the electromagnet 61 according to the present embodiment will be described. FIG. 11 is a schematic diagram illustrating a magnetic field M2 generated in an electromagnet 61A using a flat plate-shaped core 611C as a comparative example.

[0089] In the comparative example of FIG. 11, the electromagnet 61A has a flat plate-shaped core 611C. The core 611C of the comparative example differs from the core 611 of the embodiment in that it does not include a widening portion 611B as illustrated in FIG. 7 and the like. The core 611C is formed such that its dimension in the Z-axis direction is uniform across the entire X-axis direction. In other words, the core 611C is shaped such that the winding portion 611A of the core 611 of the embodiment extends to both sides in the X-axis direction where the widening portions 611B are provided.

[0090] In the case of the core 611C having the shape illustrated in FIG. 11, when the coil 612 is energized, a magnetic field M2 directed in the positive X-axis direction is generated inside the core 611C. This magnetic field M2 initially extends from the end on the positive X-axis direction side of the core 611C into the space of the resonant actuator 6 in the positive X-axis direction. Thereafter, the magnetic field branches toward the positive Z-axis direction and the negative Z-axis direction, curves, and reverses its direction to enter the interior from the positive X-axis direction ends of the first movable plate 62 and the second movable plate 63, proceeding toward the negative X-axis direction. Then, from the negative X-axis direction ends of the first movable plate 62 and the second movable plate 63, the magnetic field again extends into the space of the resonant actuator 6 in the negative X-axis direction, curves toward the negative Z-axis direction and the positive Z-axis direction, reverses its direction toward the positive X-axis direction, merges, and finally flows into the negative X-axis direction end of the core 611C.

[0091] In other words, as illustrated in FIG. 11, in the comparative example, the magnetic field M2 forms a clockwise flow on the first movable plate 62 side and a counterclockwise flow on the second movable plate 63 side when viewed from the negative Y-axis direction, which is the same as the magnetic field M1 in the embodiment illustrated in FIG. 7. However, in the comparative example, the magnetic field M2 tends to have a greater portion of the magnetic flux flowing through the space of the resonant actuator 6, that is, a larger number of air gaps, as compared with the magnetic field M1 of the embodiment. As a result, the magnetic reluctance increases.

[0092] In contrast, in the electromagnet 61 of the present embodiment, by providing the core 611 with widening portions 611B, as illustrated in FIG. 7, the air gaps in the magnetic field M1 can be confined to the gaps between the upper end surfaces of the widening portions 611B and the first movable plate 62, and between the lower end surfaces of the widening portions 611B and the second movable plate 63. Accordingly, the air gaps within the magnetic field M1 can be decreased, thereby decreasing the magnetic reluctance. As a result, magnetic force can be generated more efficiently than in the comparative example.

[0093] In the present embodiment, as illustrated in FIGS. 3 and 4, the core 611 of the electromagnet 61 is formed by laminating a plurality of electromagnetic steel sheets in the Y-axis direction. Since adjacent electromagnetic steel sheets are bonded to each other with an adhesive, the adhesive portions form air gaps that act as magnetic reluctances, making it more difficult for magnetic flux to flow through them. Because the magnetic flux generated by the coil 612 flows through the core 611 toward the movable plates 62 and 63, when the lamination direction is set to the Y-axis direction as in the present embodiment, the air gaps are positioned parallel to the direction of the magnetic flux flow. As a result, interference with the magnetic flux flow is decreased, and the energy transfer efficiency is improved.

[0094] In contrast, in a configuration in which the lamination direction is different by 90 degrees from that in the present embodiment, that is, when the lamination direction is set to the X-axis direction, the air gaps are positioned in a manner that obstructs the flow of magnetic flux, resulting in decreased efficiency.

[0095] Next, with reference to FIG. 12, the effects of the shapes of the movable plates 62 and 63 and the leaf springs 64 and 65 in the present embodiment will be described. FIG. 12 is a plan view illustrating an internal structure of the housing 2 of the pump 1 as viewed from the positive Z-axis direction side. FIG. 12 illustrates a state in which a portion of a main surface on the positive Z-axis direction side of the housing 2 has been removed from the pump 1 illustrated in FIG. 1, and the interior of the housing 2 is viewed from the first leaf spring 64 side.

[0096] When a direction (Y-axis direction) perpendicular to a direction (X-axis direction) of a magnetic field M1 generated by the electromagnet 61 is defined as a width direction, as illustrated in FIG. 12, at least a width dimension W1 of a bent portion 643 of the first leaf spring 64 is formed larger than a width dimension W2 of the first movable plate 62. It should be noted that, in FIG. 12, the same relationship applies to the second movable plate 63 and the second leaf spring 65, which are hidden on the far side in the figure, and at least the width dimension W1 of a bent portion 653 of the second leaf spring 65 is formed larger than the width dimension W2 of the second movable plate 63.

[0097] As described with reference to FIG. 7, when the electromagnet 61 is energized during the operation of the resonant actuator 6, the first movable plate 62 and the second movable plate 63 ideally move in parallel in the direction approaching the electromagnet 61 (Z-axis direction) under the effect of the magnetic field M1 generated by the electromagnet 61. However, if the magnetic field M1 has an uneven flux density across the width direction of the movable plates 62 and 63, twisting may occur during operation, such as tilting of the first movable plate 62 or the second movable plate 63 in the X-axis or Y-axis directions. In the present embodiment, by forming the width dimension W1 of the leaf springs 64 and 65 larger than the width of the movable plates 62 and 63, such twisting of the movable plates 62 and 63 during operation can be absorbed by the leaf springs 64 and 65. As a result, the first movable plate 62 and the second movable plate 63 can be moved in parallel more stably. Consequently, in a configuration where the resonant actuator 6 serves as the driving source, the pump 1 of the present embodiment can decrease noise and vibration.

[0098] In addition, the first pump chamber 7 and the second pump chamber 8 are disposed to face each other at positions at which a pair of first pistons 71 and 81 are disposed at both ends of the first movable plate 62 along a direction of the magnetic field M1 (X-axis direction). Similarly, the first pump chamber 7 and the second pump chamber 8 are disposed to face each other at positions at which a pair of second pistons 72 and 82 are disposed at both ends of the second movable plate 63 along the direction of the magnetic field M1 (X-axis direction). In a configuration including two pump chambers in this manner, two pistons are disposed on a single movable plate. Therefore, when a relationship between the width dimension W1 of the leaf springs 64 and 65 and the width dimension W2 of the movable plates 62 and 63 satisfies the above condition, the sliding of the two pistons provided on the single movable plate with respect to the respective pump chambers 7 and 8 can be stabilized, whereby the effect of suppressing twisting of the movable plates 62 and 63 can be particularly exhibited.

[0099] Next, effects relating to the arrangement of the first pump chamber 7 and the second pump chamber 8 will be described. As illustrated in FIGS. 2 and 7, of the flow channel 5 of the pump 1, the fourth flow channel 54 including the first pump chamber 7 is disposed adjacent to a position on a side (the negative X side) of the winding portion 611A of the core 611 of the electromagnet 61, across the widening portion 611B on the negative X side of the core 611, and the direction of fluid flow is along the width direction (the Y direction). Similarly, of the flow channel 5 of the pump 1, the fifth flow channel 55 including the second pump chamber 8 is disposed adjacent to a position on a side (the positive X side) of the winding portion 611A of the core 611, across the widening portion 611B on the positive X side of the core 611, and the direction of fluid flow is along the width direction (the Y direction).

[0100] Accordingly, the first piston 71 inserted into the first pump chamber 7 is disposed on the first movable plate 62 at a position adjacent to a side of the winding portion 611A across the widening portion 611B of the electromagnet 61 located on the negative X-axis direction side of the first movable plate 62. Similarly, the second piston 72 inserted into the first pump chamber 7 is disposed on the second movable plate 63 at a position adjacent to a side of the winding portion 611A (negative X-axis direction) across the widening portion 611B of the electromagnet 61 located on the negative X-axis direction side of the second movable plate 63. In the same manner, the first piston 81 inserted into the second pump chamber 8 is disposed on the first movable plate 62 at a position adjacent to a side of the winding portion 611A across the widening portion 611B of the electromagnet 61 located on the positive X-axis direction side of the first movable plate 62. Similarly, the second piston 82 inserted into the second pump chamber 8 is disposed on the second movable plate 63 at a position adjacent to a side of the winding portion 611A across the widening portion 611B of the electromagnet 61 located on the positive X-axis direction side of the second movable plate 63.

[0101] By providing widening portions 611B at both ends in the X-axis direction of the core 611 of the electromagnet 61, as illustrated in FIG. 7, a magnetic field M1 is generated such that the magnetic flux is concentrated and passes through the upper and lower end faces of the widening portions 611B. That is, when the electromagnet 61 is energized, the portion of the first movable plate 62 facing the upper end face of the widening portion 611B receives the strongest attractive force, and the portion of the second movable plate 63 facing the lower end face of the widening portion 611B receives the strongest attractive force. Therefore, by arranging the first pistons 71 and 81 and the second pistons 72 and 82 adjacent to the widening portions 611B, each piston can be positioned near the portions of the first movable plate 62 and the second movable plate 63 that experience the strongest attractive force from the electromagnet 61. As a result, it becomes possible to efficiently apply external forces in the sliding direction from the first movable plate 62 and the second movable plate 63 to the first pistons 71 and 81 and the second pistons 72 and 82, thereby improving the operational efficiency of both the first pump chamber 7 and the second pump chamber 8.

[0102] Furthermore, by arranging the first pistons 71 and 81 and the second pistons 72 and 82 in the vicinity of the portion where the first movable plate 62 and the second movable plate 63 receive the strongest attractive force from the electromagnet 61, the moving directions of the first pistons 71 and 81 and the second pistons 72 and 82 can be prevented from being twisted during the attraction motion by the attractive force generated when the electromagnet 61 is energized. Thus, the moving directions of the first pistons 71 and 81 and the second pistons 72 and 82 can be aligned with the axial direction (Z-axis direction) of the cylinders 73 and 83 of the pump chambers 7 and 8, and the operating efficiency of the first pump chamber 7 and the second pump chamber 8 can be further improved. As a result, the pump 1 of the present embodiment can realize improved performance and high efficiency in a configuration using the resonant actuator 6 as a drive source.

[0103] In addition, the first pump chamber 7 is disposed adjacent to the side of the winding portion 611A of the core 611 (negative X-axis direction) across one of the pair of widening portions 611B of the electromagnet 61, and the second pump chamber 8 is disposed adjacent to the side of the winding portion 611A of the core 611 (positive X-axis direction) across the other one of the pair of widening portions 611B. In a configuration having such two pump chambers, since two pistons are installed on a single movable plate, respectively arranging pump chambers 7 and 8 adjacent to the sides of the widening portions 611B makes it easier to equalize the external forces applied to the two pistons disposed on a single movable plate, and facilitates synchronization of the sliding of the pistons in the respective pump chambers 7 and 8. As a result, the effect of improving the operational efficiency of the pump chambers can be particularly achieved.

[0104] As illustrated in FIG. 2, it is preferable that both the first pump chamber 7 and the second pump chamber 8 be disposed on the symmetry axis CA of the housing 2. As illustrated in FIG. 7, the coil 612 of the electromagnet 61 is disposed such that its central axis coincides with the symmetry axis CA, such that the magnetic flux tends to be most concentrated on the symmetry axis CA at the central side of the coil 612. Accordingly, the first movable plate 62 and the second movable plate 63 are more likely to receive the strongest attracting force from the electromagnet 61 on the symmetry axis CA. Therefore, if the first pump chamber 7 and the second pump chamber 8 are disposed on the symmetry axis CA, the first pistons 71 and 81 and the second pistons 72 and 82 are likewise disposed on the symmetry axis CA, making it possible to efficiently apply external forces in the sliding direction from the first movable plate 62 and the second movable plate 63 to the first pistons 71 and 81 and the second pistons 72 and 82, thereby further improving the operational efficiency of the first pump chamber 7 and the second pump chamber 8.[Application Example of Pump 1]

[0105] FIG. 13 is a diagram illustrating an application example of the pump 1 according to the present embodiment. As illustrated in FIG. 13, the pump 1 according to the present embodiment can be applied, for example, to a beverage supply apparatus such as an espresso machine 100.

[0106] The espresso machine 100 includes a tank 101, a heater 102, a damper 103, and an extraction unit 104.

[0107] The tank 101 stores water used for preparing espresso. A flow channel 107 is provided between the tank 101 and the pump 1, between the pump 1 and the heater 102, and between the heater 102 and the extraction unit 104, for transporting water supplied from the tank 101.

[0108] The pump 1 pressurizes the water transported from the tank 101 and delivers it to the heater 102. In the case of the espresso machine 100, it is preferable that the pump 1 increases the water pressure, for example, up to 9 atm.

[0109] The heater 102 heats the pressurized water transported from the tank 101 and supplies it to the extraction unit 104.

[0110] The extraction unit 104 has a powder 105 of ground coffee beans packed in the lower portion inside, which is pressed downward by the damper 103. The pressurized hot water heated by the heater 102 is supplied to the pressed coffee powder 105, and coffee is extracted from the extraction hole 106 at the lower end of the extraction unit 104.

[0111] In an espresso machine, a high-pressure pump is required to extract coffee under high pressure. Therefore, in conventional espresso machines, solenoid-driven metering pumps are often applied. However, solenoid-driven metering pumps have problems such as high vibration and low efficiency.

[0112] In contrast, the pump 1 of the present embodiment employs the resonant actuator 6 as a drive source, thereby overcoming the problems of the conventional solenoid-driven metering pump and enabling the provision of a more convenient espresso machine 100.

[0113] The pump 1 can also be applied to any beverage supply apparatus requiring pressurization other than the espresso machine 100. Such a beverage supply apparatus only needs to include at least a tank that stores a beverage, the pump 1 according to the present embodiment that sucks the beverage from the tank and discharges the beverage at a predetermined pressure, and a discharge unit that dispenses the beverage discharged from the pump 1 (in the example of FIG. 13, the extraction unit 104 serves as the discharge unit).

[0114] Moreover, the pump 1 can be applied to any device other than a beverage supply apparatus requiring pressurization. Examples of such devices include industrial manufacturing equipment (such as semiconductor manufacturing apparatuses), medical devices, household facilities (such as toilets, washbasins, baths), and agricultural equipment.<First Modification>

[0115] FIG. 14 is a diagram illustrating a configuration of a flow channel 5A of a pump 1A according to a first modification. The outline of FIG. 14 corresponds to FIG. 2, but in FIG. 14, the second flow channel 52 and subsequent channels of the flow channel 5A are illustrated by broken lines, and the illustration of a portion on the positive Y-axis direction side of the electromagnet 61 within the housing 2 is omitted. In addition, while the electromagnet 61 is illustrated only in outline as a rectangle in FIG. 2, the core 611 and the coil 612 of the electromagnet 61 are illustrated in FIG. 14.

[0116] The pump 1A according to the first modification is obtained by adding a coil cooling structure to the pump 1 of the embodiment. In the pump 1A according to the first modification, as the coil cooling structure, a cooling flow channel 59 and a pair of heat-absorbing members 11 and 12 are provided.

[0117] The cooling flow channel 59 is provided branching from the flow channel 5A. In the example of FIG. 14, the cooling flow channel 59 branches off from the downstream end of the first flow channel 51, in the same manner as the second flow channel 52 and the third flow channel 53. The cooling flow channel 59 extends in the positive Y-axis direction and is configured to reach a position adjacent to the negative Y-axis side of the coil 612 of the electromagnet 61. The distal end of the cooling flow channel 59 on the positive Y-axis side is sealed. Preferably, the distal end of the cooling flow channel 59 in the Y-axis direction is located approximately at the central position of the coil 612 in the X-axis direction.

[0118] FIG. 15 is a side view illustrating an exemplary configuration of the cooling flow channel 59 and the heat-absorbing members 11 and 12 illustrated in FIG. 14. FIG. 15 is a cross-sectional view along the axial direction of the cooling flow channel 59, and in addition to the cooling flow channel 59, the heat-absorbing members 11 and 12 and the winding portion 611A of the core 611 are also illustrated in cross section.

[0119] As illustrated in FIG. 15, at the distal end of the cooling flow channel 59 on the positive Y-axis side, a first hole 59A opening toward the positive Z-axis direction and a second hole 59B opening toward the negative Z-axis direction are provided.

[0120] The pair of heat-absorbing members 11 and 12 are, for example, plate members made of a conductor such as metal, and are formed so as to be capable of surface contact with the outer peripheral surface of the cooling flow channel 59 and the outer peripheral surface of the coil 612. One of the heat-absorbing members 11 is disposed to be in surface contact with the cooling flow channel 59 and the coil 612 from the positive Z-axis direction. Further, the heat-absorbing member 11 is installed so as to block the first hole 59A of the cooling flow channel 59. The other heat-absorbing member 12 is disposed to be in surface contact with the cooling flow channel 59 and the coil 612 from the negative Z-axis direction. Further, the heat-absorbing member 12 is installed so as to block the second hole 59B of the cooling flow channel 59.

[0121] The fluid flowing in the cooling flow channel 59 toward the positive Y-axis direction enters the first hole 59A and the second hole 59B at the distal end, and comes into contact with the portions of the heat-absorbing members 11 and 12 that are exposed to the first hole 59A and the second hole 59B.

[0122] The heat-absorbing members 11 and 12 are cooled by coming into contact with the fluid through the first hole 59A and the second hole 59B. In addition, the heat-absorbing members 11 and 12 absorb heat generated by energization of the coil 612 from a contact portion with the coil 612, thereby absorbing heat from the coil 612.

[0123] Thus, in the first modification, the pump 1A can absorb heat from the coil 612 of the electromagnet 61 by using the cooling flow channel 59 and the heat-absorbing members 11 and 12, which suppresses the temperature rise of the coil 612. As a result, deterioration in pump performance caused by the temperature rise of the coil 612 can be suppressed, thereby preventing performance degradation of the pump 1A due to heat generated by its drive source.

[0124] It is preferable that the cooling flow channel 59 be provided so as to branch from the flow channel 5A on the upstream side from the first pump chamber 7 and the second pump chamber 8. This is because, on the upstream side of the first pump chamber 7 and the second pump chamber 8, the fluid is in a state before being pressurized in the pump chambers, and thus the effect of temperature change due to pressurization is eliminated, allowing a stable cooling effect to be obtained.

[0125] In the example illustrated in FIG. 14, the cooling flow channel 59 is illustrated as being provided to branch from the flow channel 5A; however, the flow channel 5A may alternatively serve as the cooling flow channel 59. In this case, a first hole 59A and a second hole 59B are provided at any positions in the flow channel 5A, and the heat-absorbing members 11 and 12 are installed at positions corresponding to the first hole 59A and the second hole 59B provided in the flow channel 5A. In any case, the cooling flow channel 59 can be encompassed by the expression "a portion of the flow channel 5A."<Second Modification>

[0126] FIG. 16 is a diagram illustrating a configuration of a flow channel 5B of a pump 1B according to a second modification. The outline of FIG. 16 corresponds to that of FIG. 2.

[0127] As illustrated in FIG. 16, the arrangement of the inlet 3 and the outlet 4 may be changed. In the example of FIG. 16, the inlet 3 is disposed on the X-negative side portion of the side surface 25 of the housing 2, and the outlet 4 is disposed on the X-positive side portion of the side surface 26. The inlet 3 and the outlet 4 are both connected in the Y-axis direction. The upstream end of the first flow channel 51 of the flow channel 5B is connected substantially perpendicularly to the inlet 3. Similarly, the downstream end of the eighth flow channel 58 of the flow channel 5B is connected substantially perpendicularly to the outlet 4.

[0128] In addition to the example illustrated in FIG. 16, the inlet 3 and the outlet 4 may be disposed at arbitrary positions on the housing 2, for example, in a configuration in which the inlet 3 and the outlet 4 are disposed on a pair of main surfaces 21 and 22.<Third Modification>

[0129] FIG. 17 illustrates the configuration of a flow channel 5C of a pump 1C according to a third modification. The outline of FIG. 17 corresponds to FIG. 2.

[0130] As illustrated in FIG. 17, in the flow channel 5C, the first pump chamber 7 and the second pump chamber 8 may be disposed at least in the fourth flow channel 54 and the fifth flow channel 55, and may be disposed at positions other than the symmetry axis CA. For example, as illustrated in FIG. 17, the first pump chamber 7 may be disposed on the upstream side of the flow channel 5C on the negative Y-axis direction side of the symmetry axis CA. Alternatively, as illustrated in FIG. 17, the second pump chamber 8 may be disposed on the downstream side of the flow channel 5C on the positive Y-axis direction side of the symmetry axis CA.

[0131] When the positions of the first pump chamber 7 and the second pump chamber 8 in the Y-axis direction are the same, the first movable plate 62 and the second movable plate 63 can receive an equal attractive force from the electromagnet 61, such that the pumping performance of the first pump chamber 7 and the second pump chamber 8 can be equalized.<Fourth Modification>

[0132] FIG. 18 is a schematic view of a cross-sectional shape of a pump 1D according to a fourth modification along the symmetry axis CA. The outline of FIG. 18 corresponds to FIG. 5.

[0133] As illustrated in FIG. 18, only a single piston may be provided in one pump chamber. In the example of FIG. 18, only the first piston 71 inserted into the first pump chamber 7 is mounted on the first movable plate 62, and only the second piston 82 inserted into the second pump chamber 8 is mounted on the second movable plate 63.

[0134] In the example of FIG. 18, the cylinder 73A of the first pump chamber 7 has an opening only on the first movable plate 62 side such that the first piston 71 can be inserted therethrough, and is sealed without having an opening on the second movable plate 63 side. Similarly, a cylinder 83A of the second pump chamber 8 has an opening only on the second movable plate 63 side such that the second piston 82 can be inserted therethrough, and is sealed without having an opening on the first movable plate 62 side.

[0135] Even in such a configuration in which only a single piston is provided in one pump chamber, for example, as illustrated by the arrows in FIG. 18, if the lower end of the sliding range of the first piston 71 is extended beyond the symmetry axis CA to the vicinity of the lower end of the fourth flow channel 54, and the upper end of the sliding range of the second piston 82 is extended beyond the symmetry axis CA to the vicinity of the upper end of the fifth flow channel 55, pump performance similar to that of the pump 1 of the embodiment can be achieved.<Fifth Modification>

[0136] FIG. 19 illustrates the configuration of a flow channel 5E of a pump 1E according to the fifth modification. The outline of FIG. 19 corresponds to FIG. 2.

[0137] As illustrated in FIG. 19, only a single pump chamber 7A may be provided in the flow channel 5E. In this case, the pump chamber 7A is preferably disposed on the symmetry axis CA and on the symmetry axis CB, that is, at the position of the center line CO of the housing 2. Thus, the driving force applied from the first movable plate 62 to the first piston and the driving force applied from the second movable plate 63 to the second piston can be made more uniform, thereby further stabilizing the pump performance.

[0138] When the pump chamber 7A is disposed in this manner, the flow channel 5E may include, in addition to the first flow channel 51 connected to the inlet 3 and the eighth flow channel 58 connected to the outlet 4, only an intermediate flow channel 55A connecting the downstream end of the first flow channel 51 and the upstream end of the eighth flow channel 58. The intermediate flow channel 55A is disposed to extend along the Y-axis direction with the symmetry axis CB as its axis. The intermediate flow channel 55A may, for example, be disposed to pass through the winding portion 611A of the core 611 of the electromagnet 61 and the coil 612 along the Y-axis direction.

[0139] Further, in the configuration of the flow channel 5 illustrated in FIG. 2, only either the first pump chamber 7 or the second pump chamber 8 may be provided.<Sixth Modification>

[0140] FIG. 20 illustrates the configuration of a flow channel 5F of a pump 1F according to the sixth modification. The outline of FIG. 20 corresponds to FIG. 2.

[0141] As illustrated in FIG. 20, the inlet 3 and the outlet 4 may be disposed on the same side surface of the housing 2. In the example of FIG. 20, in this configuration, both the inlet 3 and the outlet 4 are disposed on the side surface 25 of the housing 2, the inlet 3 being on the portion of the side surface 25 in the negative X-axis direction, and the outlet 4 being on the portion of the side surface 25 in the positive X-axis direction. Both the inlet 3 and the outlet 4 are in communication in the Y-axis direction.

[0142] In the example of FIG. 20, the flow channel 5F includes a first flow channel 91, a second flow channel 92, a third flow channel 93, and a fourth flow channel 94. The first flow channel 91 and the second flow channel 92 are connected to the inlet 3 at their upstream ends. The first flow channel 91 is disposed to extend in the positive Y-axis direction, and the second flow channel 92 is disposed to extend in the positive X-axis direction.

[0143] The third flow channel 93 is connected at its upstream end to the downstream end of the first flow channel 91, and is disposed to extend in the positive X-axis direction. The fourth flow channel 94 is connected at its upstream end to the downstream end of the third flow channel 93. The fourth flow channel 94 is disposed to extend in the negative Y-axis direction.

[0144] The second flow channel 92 and the fourth flow channel 94 are connected to the outlet 4 at their downstream ends.

[0145] In the example of FIG. 20, the first to fourth flow channels 91 to 94 of the flow channel 5F are disposed to surround the outer periphery of the electromagnet 61 of the resonant actuator 6 when viewed in the Z-axis direction. The first flow channel 91 and the fourth flow channel 94 are disposed to extend along the short sides of the rectangular outer shape of the electromagnet 61. The second flow channel 92 and the third flow channel 93 are disposed to extend along the long sides of the rectangular outer shape of the electromagnet 61.

[0146] Further, in the case of the flow channel 5F illustrated in FIG. 20, a first pump chamber 95 is disposed at the center in the extending direction (X-axis direction) of the third flow channel 93, and a second pump chamber 96 is disposed at the center in the extending direction (X-axis direction) of the second flow channel 92. That is, both the first pump chamber 95 and the second pump chamber 96 are preferably disposed on the symmetry axis CB extending in the Y-axis direction. In the example illustrated in FIG. 20, since the first pump chamber 95 and the second pump chamber 96 are disposed in this manner, the first movable plate 62 and the second movable plate 63 of the resonant actuator 6 are formed such that the end faces on the positive Y-axis direction side in the width direction (Y-axis direction) extend from the first pump chamber 95 and the third flow channel 93 to a position further in the positive Y-axis direction, and the end faces on the negative Y-axis direction side extend from the second pump chamber 96 and the second flow channel 92 to a position further in the negative Y-axis direction.

[0147] FIG. 21 illustrates an example of a configuration in which a coil cooling structure similar to that of the first modification is applied to the pump 1F according to the sixth modification. The outline of FIG. 21 corresponds to FIG. 14.

[0148] The pump 1F according to the sixth modification has a cooling flow channel 97 and a heat-absorbing member 13 as the coil cooling structure.

[0149] The cooling flow channel 97 branches from the flow channel 5F. In the example of FIG. 21, the cooling flow channel 97 branches in the positive X-axis direction at a position (on the symmetry axis CA) in the center of the extending direction (Y-axis direction) of the first flow channel 91. The cooling flow channel 97 extends from the first flow channel 91 in the positive X-axis direction and reaches a position adjacent to the negative X-axis direction side of the widening portion 611B of the core 611 of the electromagnet 61. The tip portion of the cooling flow channel 97 on the positive X-axis direction side is sealed.

[0150] The tip portion of the cooling flow channel 97 on the positive X-axis direction side is provided with a hole 97A opened in the positive Z-axis direction. The heat-absorbing member 13 is, for example, a plate of a conductive material such as metal, and is formed to be in surface contact with the outer surface of the cooling flow channel 97 and the outer surface of the widening portion 611B on the negative X-axis direction side. The heat-absorbing member 13 is disposed to make surface contact with the cooling flow channel 97 and the widening portion 611B from the positive Z-axis direction. The heat-absorbing member 13 is also disposed to block the hole 97A of the cooling flow channel 97.

[0151] Fluid flowing through the cooling flow channel 97 in the positive X-axis direction flows into the hole 97A at the tip portion and comes into contact with the portion of the heat-absorbing member 13 exposed in the hole 97A. The heat-absorbing member 13 is cooled by contact with the fluid through the hole 97A. In addition, the heat-absorbing member 13 absorbs heat transferred to the core 611 from the coil 612 through the contact with the widening portion 611B, thereby indirectly absorbing heat from the coil 612.

[0152] It should be noted that the coil cooling structure according to the sixth modification may have a configuration in which a pair of heat-absorbing members 13 are disposed on both sides of the cooling flow channel 97 in the Z-axis direction, as in the first modification illustrated in FIG. 15. In this case, one of the pair of heat-absorbing members 13 is disposed to make surface contact with the cooling flow channel 97 and the widening portion 611B from the positive Z-axis direction, and the other one is disposed to make surface contact with the cooling flow channel 97 and the widening portion 611B from the negative Z-axis direction.

[0153] As described above, in the configuration in which the coil cooling structure is applied to the pump 1F according to the sixth modification, heat can be absorbed from the widening portion 611B of the core 611 of the electromagnet 61 by using the cooling flow channel 97 and the heat-absorbing member 13, thereby suppressing the temperature rise of the coil 612 through the widening portion 611B. As a result, deterioration of pump performance due to temperature rise of the coil 612 can be suppressed, thereby suppressing performance deterioration caused by heat generation of the drive source of the pump 1F.

[0154] It is to be noted that the cooling flow channel 97 is preferably branched from a flow channel upstream of the first pump chamber 95 and the second pump chamber 96 in the flow channel 5F. This is because, upstream of the first pump chamber 95 and the second pump chamber 96, the fluid is in a state before being pressurized in the pump chambers, such that there is no effect of temperature change due to pressurization, enabling a stable cooling effect.

[0155] In the example of FIG. 21, the cooling flow channel 97 is provided as a branch from the flow channel 5F; however, the flow channel 5F itself may be used as the cooling flow channel 97. In this case, a hole 97A is provided at any position selected in the flow channel 5F, and the heat-absorbing member 13 is disposed at the selected position at which the hole 97A is provided in the flow channel 5F. In any case, the cooling flow channel 97 can be considered as "a portion of the flow channel 5F."<Seventh Modification>

[0156] FIG. 22 is a schematic view of a cross-sectional shape of a pump 1G according to the seventh modification along the symmetry axis CA. The outline of FIG. 22 corresponds to FIG. 5.

[0157] As illustrated in FIG. 22, only one of a pair of movable portions may be provided. In the example of FIG. 22, only the first movable plate 62 and the first leaf spring 64 are provided.

[0158] In the example of FIG. 22, the cylinder 73B of the first pump chamber 7 is formed to open only on the first movable plate 62 side (the positive Z-axis direction side) to allow insertion of the first piston 71, and is sealed on the negative Z-axis direction side without opening. The cylinder 83A of the second pump chamber 8 is also formed to open only on the first movable plate 62 side (the positive Z-axis direction side) to allow insertion of the first piston 81, and is sealed on the negative Z-axis direction side without opening.

[0159] Even in a configuration in which only a single piston is provided in one pump chamber, as illustrated by arrows in FIG. 22, pump performance similar to that of the pump 1 of the embodiment can be achieved by extending the lower end of the sliding range of the first piston 71 beyond the symmetry axis CA to the vicinity of the lower end of the fourth flow channel 54, and by extending the lower end of the sliding range of the first piston 81 beyond the symmetry axis CA to the vicinity of the lower end of the fifth flow channel 55.

[0160] The present embodiment has been described with reference to specific examples. However, the present disclosure is not limited to these specific examples. Embodiments in which a person skilled in the art has appropriately modified the design are also encompassed within the scope of the present disclosure, provided that they retain the features of the present disclosure. The elements, their arrangements, conditions, shapes, and the like in the foregoing embodiments are not limited to the illustrated examples and may be appropriately modified. The combinations of elements in the foregoing embodiments may be altered as long as no technical conflicts arise.

[0161] In the foregoing embodiments, a configuration using the first pistons 71 and 81 and the second pistons 72 and 82 is illustrated as an example of "volume changing members that operate to decrease the volumes of the pump chambers 7 and 8 in accordance with the attraction motion of the movable plates 62 and 63 toward the electromagnet 61, and to increase the volumes of the pump chambers 7 and 8 in accordance with the separation motion of the movable plates 62 and 63 moving away from the electromagnet 61 by the biasing forces f1 and f2 of the leaf springs 64 and 65 when the electromagnet 61 is switched to a de-energized state after the attraction motion." However, elements other than pistons may be applied. Examples of such elements include diaphragms, bellows, and the like.

[0162] This international application claims priority to U.S. Provisional Application No. 63 / 522,141, filed on June 21, 2023, and the entire contents of U.S. Provisional Application No. 63 / 522,141 are incorporated herein by reference.REFERENCE SIGNS LIST

[0163] 1, 1A, 1B, 1C, 1D, 1E, 1F Pump 5, 5A, 5B, 5C, 5E, 5F Flow channel 6 Resonant actuator 61 Electromagnet (fixed portion) 611 Core 611A Winding portion 611B Pair of widening portions 612 Coil 62 First movable plate (movable portion) 63 Second movable plate (movable portion) 64 First leaf spring (movable portion) 641 Central portion 642 Pair of fixed end portions 643 Bent portion 65 Second leaf spring (movable portion) 651 Central portion 652 Pair of fixed end portions 653 Bent portion 7 First pump chamber 71 First piston (volume changing member) 72 Second piston (volume changing member) 74 Suction valve 75 Discharge valve 8 Second pump chamber 81 First piston (volume changing member) 82 Second piston (volume changing member) 9 Support 59, 97 Cooling flow channel 11, 12, 13 Heat-absorbing member 100 Espresso machine (beverage supply apparatus) 101 Tank 104 Extraction unit (discharge unit) W1 Width dimension of leaf spring W2 Width dimension of movable plate

Claims

1. A pump comprising: a fixed portion in which an electromagnet is disposed; movable portions that are attracted to the fixed portion by a magnetic field generated at a time of energization of the electromagnet, and that perform a vibrating motion moving away from the fixed portion by biasing forces at a time of de-energization of the electromagnet, the biasing forces being generated during attraction; a flow channel through which a fluid flows; pump chambers disposed in the flow channel, the pump chambers being configured to suck and discharge the fluid in conjunction with a motion of the movable portions; a cooling flow channel disposed in a portion of the flow channel; and a heat-absorbing member that is cooled by the fluid flowing through the cooling flow channel and absorbs heat from a coil or a core of the electromagnet.

2. The pump according to claim 1, wherein the cooling flow channel branches from a portion of the flow channel on an upstream side of the pump chambers.

3. A beverage supply apparatus comprising: a tank configured to store a beverage; the pump according to claim 1 or 2, the pump being configured to suck the beverage in the tank and discharge the beverage at a predetermined pressure; and a discharger configured to discharge the beverage discharged from the pump.

Images