Diaphragm pump

This application claims the benefit of Japanese Patent Application No. 2005-280548 filed on Sep. 27, 2005 and Japanese Patent Application NO. 2006-136693 filed on May 16, 2006.

BACKGROUND

1. Field

The present embodiments relate to a diaphragm pump.

2. Related Art

A diaphragm pump, as disclosed in, for example, Japanese Unexamined Patent Application Publication No. 11-182413, is configured such that a pump chamber (variable volume chamber) is formed by a diaphragm. A pair of flow channels connected with the pump chamber is provided with a pair of check valves, which are different in the direction of flow (a suction-side check valve, which allows the flow of fluid to the pump chamber, and a discharge-side check valve, which allows the flow of fluid from the pump chamber). When the diaphragm is vibrated, since the volume of the pump chamber changes, and the operation of opening the suction-side check valve during the stroke in which the volume increases, and the operation of opening the discharge-side check valve during the stroke in which the volume reduces, are repeated, a pumping action is obtained. The diaphragm is made of elastic (vibrational) materials, for example, rubber and piezoelectric vibrator.

In this diaphragm pump, as described above, since the operation of opening the suction-side check valve during the stroke in which the volume of the pump chamber increases, and the operation of opening the discharge-side check valve during the stroke in which the volume reduces, are repeated, pulsation in the discharge port is inevitable.

A diaphragm pump with half the cycle of the pulsation has been disclosed (Japanese Patent Application No. 2004-154991). According to this diaphragm pump, an upper pump chamber and a lower pump chamber (a pair of pump chambers) are respectively formed above and below a diaphragm by the diaphragm. A single suction port and a single discharge port are provided. First and second suction-side check valves, which allow the flow of fluid from the suction port to the pair of pump chambers and do not allow the flow of fluid in the reverse direction are provided between the pair of pump chambers, and the suction port. First and second discharge-side check valves, which allow the flow of fluid from the pair of pump chambers to the discharge port and do not allow the flow of fluid in the reverse direction are provided between the pair of pump chambers and the discharge port (4-valve diaphragm pump).

The 4-valve diaphragm pump can basically be configured by forming recessed parts, which define an upper pump chamber and a lower pump chamber, in upper and lower housings, which sandwich a diaphragm, stacking these housings in order, and forming flow channels which communicates a pair of pump chambers and the suction and discharges ports, in the upper and lower housings. However, there is a need for a 4-valve diaphragm pump that ensures liquid tightness of connecting parts of the flow channels formed over the upper housing and the lower housing or the liquid tightness of the suction flow channel and the discharge flow channel, with high reliability and durability.

SUMMARY

One exemplary object of the present embodiments is to provide a 4-valve diaphragm pump that is liquid tight at the connecting parts of flow channels formed over an upper housing and a lower housing. A second exemplary object of the present embodiments is to provide a 4-valve diaphragm pump capable of ensuring the liquid tightness of a suction flow channel and a discharge flow channel with high reliability and durability.

In a present embodiment, a diaphragm pump includes an upper housing, a diaphragm, and a lower housing which are stacked in order. Recessed parts are respectively formed in the surfaces of the upper and lower housings facing the diaphragm to define an upper pump chamber and a lower pump chamber above and below the diaphragm. A suction port and a discharge port are formed in the lower housing to communicate with the lower pump chamber. Branch channels are formed in the lower housing and the upper housing to communicate the suction port and the discharge port with the upper pump chamber. Suction-side check valves are respectively provided between the suction port and the upper pump chamber and between the suction port and the lower pump chamber. Discharge-side check valves are respectively provided between the discharge port and the upper pump chamber and between the discharge port and the lower pump chamber. The branch channels include holes formed in either the upper housing or the lower housing, a protruding cylindrical part fitted into the hole, and a sealing ring disposed in an annular gap formed between the hole and the protruding cylindrical part such that a compressive force is generated radially.

Although the upper housing can theoretically be composed of one member, it is practical that the upper housing is composed of two members in a case where the upper housing is a molded article made of a resin material. If the upper housing is composed of two members, a problem occurs in the structure in which the liquid tightness of the suction flow channel and the discharge flow channel is ensured. The present embodiments disclose a suitable liquid-tight structure in a case where the upper housing is composed of two members.

In a present embodiment, the upper housing is composed of two members. The upper housing is composed of a pump chamber plate, which is stacked on the diaphragm and has a recessed part for forming an upper pump chamber and a blind plate stacked on the pump chamber plate. A pair of an inter-plate suction flow channel and an inter-plate discharge flow channel, which communicates the suction port and the discharge port with the upper pump chamber, and which constitute parts of the branch channels is formed between the pump chamber plate and the blind plate. The inter-plate suction flow channel and the inter-plate discharge flow channel includes a pair of protruding parts formed in any one of the pump chamber plate and the blind plate, a pair of recessed groove parts which are formed in the other one of the pump chamber plate and the blind plate to allow the pair of protruding parts to fit thereinto, and a pair of sealing rings which are disposed in a pair of closed curve gaps between the pair of protruding parts and the pair of recessed groove parts such that a compressive force is generated radially.

In another embodiment, the upper housing is composed of two members. The upper housing is composed of an upper plate, which is stacked on the diaphragm and a pair of lid plates that are members separate from the upper plate. The upper plate is formed with recessed parts, which are opened to the front and back of the upper plate to form the upper pump chamber, and a pair of an open suction flow channel groove and an open discharge flow channel groove which communicates with the suction port and the discharge port with the upper pump chamber. Any one of the upper plates and the pair of lid plates is formed with protruding parts corresponding to the open suction flow channel groove and the open discharge flow channel groove. The other one of the upper plates and the pair of lid plates is formed with recessed groove parts to allow the pair of protruding parts to fit thereinto. A pair of sealing rings are interposed between the protruding parts and the recessed groove parts such that a compressive force is generated radially.

In one exemplary embodiment, the protruding parts, the recessed groove parts, and the sealing rings are elliptical.

By keeping a compressive force in the stacked direction of the upper housing, the diaphragm, and the lower housing from being applied to any of the sealing rings, and allowing a compressive in a direction (radial direction) orthogonal to the stacked direction to be applied to the sealing rings, the liquid tightness can be ensured with high durability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exploded state showing one exemplary embodiment of a diaphragm pump;

FIG. 2 is a sectional view of the exploded state according to FIG. 1;

FIG. 3 is a plan view of an exemplary lower housing;

FIG. 4 is a sectional view taken along line IV-IV of FIG. 3;

FIG. 5 is a sectional view taken along line V-V of FIG. 3;

FIG. 6 is a plan view of an upper housing on the side of a pump chamber plate;

FIG. 7 is a plan view of the pump chamber plate on the side of a recessed part for forming a pump chamber;

FIG. 8 is an exploded perspective view of a bimorph-type piezoelectric vibrator;

FIG. 9 is a perspective view showing the relationship between the bimorph-type piezoelectric vibrator and a modified D-type sealing ring;

FIG. 10 is a plan view of principal parts of the piezoelectric vibrator;

FIGS. 11A and 11B are conceptual diagrams, in different vibrating directions, of a diaphragm of a 4-valve diaphragm pump to which the one exemplary embodiment is applied;

FIG. 12 is a perspective view showing another embodiment, including a section corresponding to FIG. 4;

FIG. 13 is an enlarged sectional view of principal parts of the embodiment of FIG. 12;

FIG. 14 is a perspective view that illustrates a blind plate of the embodiment of FIG. 12.

FIG. 15 is a perspective view showing still another embodiment, including a section corresponding to FIG. 4;

FIG. 16 is an enlarged sectional view of principal parts of the embodiment of FIG. 15; and

FIG. 17 is an enlarged perspective view of the principal parts of the embodiment of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrated embodiments are obtained by applying the present embodiments to a 4-valve diaphragm pump that the present applicant proposed the principle in Japanese Patent Application No. 2004-154991. One embodiment thereof will be described with reference to FIGS. 1 to 7. In one exemplary embodiment, the diaphragm pump has an upper housing 10, a lower housing 20, and a piezoelectric vibrator 30, and is in the shape of a flat rectangular parallelepiped as a whole. The upper housing 10 is composed of a blind plate 101 and a pump chamber plate 102, and all the blind plate 101, the pump chamber plate 102, and the lower housing 20 are molded articles made of a resin material.

The lower housing 20 is a member in the shape of a flat rectangular parallelepiped, which is most large-sized and has a complicate shape, among the molded articles. In the lower housing, a recessed part 20a for forming a pump chamber is formed so as to be open to the side opposing the piezoelectric vibrator 30, and a suction port 31 and a discharge port 32, which are molded integrally and parallel to each other, are formed so as to protrude from one surface of flat peripheral four surfaces of the lower housing (refer to FIGS. 1 to 5).

The lower housing 20 is formed with a suction-side flow channel 24H communicating with the suction port 31, and a discharge-side flow channel 25D communicating with the discharge port 32. Inner ends of the suction-side flow channel 24H and the discharge-side flow channel 25D are respectively formed with flow channel enlarged parts 24Ha and 25Da communicating with the recessed part 20a for forming a pump chamber. Valve-receiving recessed parts 24Hb and 25Db are respectively formed at the ends of the flow channel enlarged parts 24Ha and 25Da on the side of the recessed part 20a for forming a pump chamber.

A suction-side umbrella unit (suction-side check valve unit) 21U and a discharge-side umbrella unit (discharge-side check valve unit) 22U are adhesively fixed to the valve-receiving recessed parts 24Hb and 25Db, respectively. The suction-side umbrella unit 21U and the discharge-side umbrella unit 22U have the same structure except that their mounting directions are different from each other. A central part of a unit plate 21a (unit plate 22a) whose peripheral edge serves as an adhesive joint 21b (adhesive joint 22b) to be adhered to the valve-receiving recessed part 24Hb (valve-receiving recessed part 25Db) is formed with an umbrella mounting hole 21c (umbrella mounting hole 22c), and a peripheral edge of the umbrella mounting hole 21c (umbrella mounting hole 22c) is formed with a plurality of flow channel holes 21d (flow channel holes 22d).

An umbrella part 21g (umbrella part 22g) of an umbrella 21f (umbrella 22f) whose central shaft 21e (central shaft 22e is mounted into the umbrella mounting hole 21c (umbrella mounting hole 22c) plugs up the flow channel holes 21d (flow channel holes 22d) normally. When a pressure beyond a rated value is applied to the umbrella part 21g (umbrella part 22g) from the flow channel holes 21d (flow channel holes 22d) side, the umbrella part 21g (umbrella part 22g) deforms elastically, and thus the flow channel holes 21d (flow channel holes 22d) are opened.

In the suction-side umbrella unit 21U or the discharge-side umbrella unit 22U, the adhesive joint 21b (22b) is adhesively fixed to the valve-receiving recessed part 24Hb or 25Db, with their front and back reversed. The suction-side umbrella unit 21U allows the flow of fluid from the suction port 31 to the recessed part 20a for forming a pump chamber (pump chamber 23), and does not allow the flow of fluid reverse thereto, and the discharge-side umbrella unit 22U allows the flow of fluid from the recessed part 20a for forming a pump chamber (pump chamber 23) to the discharge port 32, and does not allow the flow of fluid reverse thereto. The unit plates 21a and 22a of the suction-side and discharge-side umbrella units 21U and 22U may be formed as one substrate.

The lower housing 20, which is a single body that does not require a lid as a separate body, is formed with the suction-side flow channel 24H and the discharge-side flow channel 25D, which are closed between the suction port 31 and the recessed part 20a for forming a pump chamber and between the discharge port 32 and the recessed part 20a for forming a pump chamber. The lower housing 20 is formed with a sealing ring groove 20b, which is located around the recessed part 20a for forming a pump chamber. The sealing ring groove 20b is in the shape of a modified letter “D” having a large circular-arc part 20b1 that is a partial circle larger than a semicircle, and a straight part 20b2 whose connects both ends of the large circular-arc part 20b1 together by a straight line.

The suction-side umbrella unit 21U and the discharge-side umbrella unit 22U, i.e., the valve-receiving recessed parts 24Hb and 25Db (umbrella parts 21g and 22g) are inclined (non-parallel) with respect to the plane of a piezoelectric vibrator 300. When a plane orthogonal to the piezoelectric vibrator 30, including the axis of the suction port 31 (discharge port 32), is considered, the inclined direction is a direction in which the plane is separated apart from the piezoelectric vibrator 30 as it goes toward the inner end of the suction port 31 (discharge port 32) and approaches the piezoelectric vibrator as it goes to the near side. If the suction-side umbrella unit 21U and the discharge-side umbrella unit 22U are inclined in this way, the lower housing 20 can be made thin without sacrificing the channel sectional area of the suction port 31 and the discharge port 32.

For example, as shown in FIG. 4, the surface (unit plate 21a (umbrella part 21g) of the suction-side umbrella unit 21U) of the valve-receiving recessed part 24Hb and the plane of the piezoelectric vibrator 30 in a free state, which are non-parallel, forms an angle α. A flow channel in a suction-side check valve (suction-side umbrella unit 21U) is not orthogonal to the piezoelectric vibrator 30. The axis of the suction port 31 (suction-side flow channel 24H) is parallel to the plane of the piezoelectric vibrator 30. The direction of the angle α is a direction in which the unit plate 21a (umbrella part 21g) of the suction-side umbrella unit 21U is separated from the piezoelectric vibrator 30 as it goes toward the inner end (left side of FIG. 4) of the suction port 31 (suction-side flow channel 24H), and approaches the piezoelectric vibrator 30 as it goes to the near side (right side of FIG. 4).

As shown in FIG. 5, the surface (unit plate 22a (umbrella part 22g) of the discharge-side umbrella unit 22U) of the valve-receiving recessed part 24Db and the plane of the piezoelectric vibrator 30 in a free state, which are non-parallel, forms an angle α. For example, a flow channel in a discharge-side check valve (discharge-side umbrella unit 22U) is not orthogonal to the piezoelectric vibrator 30. The axis of the discharge port 32 (discharge-side flow channel 24D) is parallel to the plane of the piezoelectric vibrator 30. The direction of the angle α is a direction in which the unit plate 22a (umbrella part 22g) of the discharge-side umbrella unit 22U is separated from the piezoelectric vibrator 30 as it goes toward the inner end (left side of FIG. 5) of the discharge port 32 (discharge-side flow channel 25D), and approaches the piezoelectric vibrator 30 as it goes to the near side (right side of FIG. 5).

The lower housing 20 is further formed with branch channels 24Hd and 25Dd, which branch from the suction-side flow channel 24H and the discharge-side flow channel 25D, and which are opened toward the pump chamber plate 102 (upper housing 10). The pump chamber plate 102 is formed with communicating holes (branch channel) 41 and 42 communicating with the branch channels 24Hd and 25Dd. An inter-plate suction flow channel 14H and an inter-plate discharge flow channel 15D communicating with the communicating holes 41 and 42, are formed between the blind plates 101 and the pump chamber plate 102 which constitute the upper housing 10. For example, the pump chamber plate 102 is formed with protruding cylindrical parts 41a and 42a which fit into the branch channels 24Hd and 25Dd, and the communicating holes 41 and 42 are formed in the centers of the protruding cylindrical parts 41a and 42a.

Open ends of the branch channels 24Hd and 25Dd of the lower housing 20 are respectively formed with large-diameter stepped parts 24He and 25De, which have a larger diameter than the outer diameter of the protruding cylindrical parts 41a and 42a. When the protruding cylindrical parts 41a or 42a are fitted into branch channels 24Hd or 25Dd, as shown in FIGS. 4 and 5, an annular gap 41c or 42c is formed between the protruding cylindrical part 41a or 42a, and the large-diameter stepped part 24He or 25De. An O-ring (sealing ring) 41b or 42b is inserted into the annular gap 41c or 42c.

The inner diameter of the O-ring 41b or 42b is set to be smaller than the outer diameter of the protruding cylindrical part 41a or 42a, and the outer diameter thereof is set to be greater than the large-diameter stepped part 24He or 25De. The O-ring is kept in a state where it is brought into close contact with the protruding cylindrical part 41a or 42a and large-diameter stepped part 24He or 25De, thereby generating compressive force in its radial direction. For example, the O-ring 41b or 42b keeps a space between the branch channel 24Hd or 25Dd and the protruding cylindrical part 41a or 42a (communicating hole 41 or 42) liquid-tight.

The length (thickness) d1 (FIG. 4 or FIG. 5) of the annular gap 41c or 42c in the stacked direction is set to be greater than the thickness (diameter of a section) of the O-ring 41b or 42b. This length d1 is ensured uniformly. For example, when the protruding cylindrical parts 41a and 42a are respectively inserted into the branch channels 24Hd and 25Dd, an entrance regulating surface 41d or 42d of the pump chamber plate 102 abuts on an abutting surface 24Hi or 25Di, which faces the entrance regulating surface 41d or 42d. The insertion (entrance) position of the protruding cylindrical part 41a or 42a is regulated. The O-ring 41b or 42b does not receive a compressive force in the stacked direction from the lower housing 20 and the pump chamber plate 102. Any force that makes the lower housing 20 and the pump chamber plate 102 separated in the stacked direction from the O-rings 41b and 42b is not applied to the lower housing and the pump chamber plate.

Since a compressive force that is uniform as a whole is applied to the piezoelectric vibrator 30 from the stacked direction, vibration of the piezoelectric vibrator 30 is also uniformly generated in the stacked direction. The operation of the piezoelectric vibrator 30 can be stabilized, and a fluid can be generated efficiently.

The surface of the pump chamber plate 102, which faces piezoelectric vibrator 30 becomes a recessed part 40a for forming a pump chamber (FIGS. 2, 4, and 5). A substantially central part of the pump chamber plate is mounted with a suction-side umbrella 11 and a discharge-side umbrella 12 respectively corresponding to the suction-side umbrella unit 21U and the discharge-side umbrella unit 22U. The suction-side umbrella 11 and the discharge-side umbrella 12 are not drawn on FIG. 2. For example, in the positions vertically corresponding to the suction-side umbrella unit 21U and the discharge-side umbrella unit 22U, the pump chamber plate 102 is formed with umbrella mounting holes 11a and 12a. The peripheral edges of the umbrella mounting holes 11a and 12a are respectively formed with a plurality of flow channel holes 11b or 12b.

The suction-side umbrella 11 or the discharge-side umbrella 12 has a central shaft 11c (central shaft 12c), which is mounted to the umbrella mounting hole 11a (umbrella mounting hole 12a), and an umbrella part 11d (umbrella part 12d) which plugs up the flow channel holes 11b (flow channel holes 12b) normally. When a pressure beyond a rated value is applied to the umbrella part 11d (umbrella part 12d) from the flow channel holes 11b (flow channel holes 12b) side, the umbrella part 11d (umbrella part 12d) deforms elastically to open the flow channel holes 11b (flow channel holes 12b).

The suction-side umbrella 11 allows the flow of fluid from the blind plate 101 side to the recessed part 40a for forming a pump chamber (pump chamber 13), and does not allow the flow of fluid reverse thereto, but the discharge-side umbrella 12 allows the flow of fluid from the recessed part 40a for forming a pump chamber (pump chamber 13) to the blind plate 101 side, and does not allow the flow of fluid reverse thereto.

The blind plate 101 has substantially the same planar shape as the lower housing 20 so as to overlap the lower housing 20. The blind plate 101 is formed with a recessed part 14Ha, which forms an inter-plate suction flow channel 14H that communicates a communicating hole 41 with the suction-side umbrella 11, and a recessed part 15Da for forming an inter-plate discharge flow channel 15D that communicates a communicating hole 42 with the discharge-side umbrella 12, between itself and the pump chamber plate 102 (refer to FIG. 2 and FIGS. 4 to 6). Sealing ring grooves 14Hb and 14Dc for allowing elliptical O-rings (sealing rings) 15Da and 15Da to be fitted thereinto are formed around the recessed parts 14Ha and 15Da, respectively. The blind plate 101 is also formed with a recessed part 10a (FIGS. 2 and 6) for allowing the pump chamber plate 102 to be fitted thereinto.

The pump chamber plate 102 and the blind plate 101 are respectively formed with positioning fitting protrusions 40c and fitting holes 10c (FIG. 1) which are fitted to each other in a state where the elliptical O-ring 14Hb and 15Db are fitted into the recessed parts 14Ha and 15Da, for example, respectively. By bonding the positing fitting protrusions and the fitting holes together after they are fitted to each other, the liquid-tight inter-plate suction flow channel 14H that is liquid-tight from the communicating hole 41 to the suction-side umbrella 11 and the inter-plate discharge flow channel 15D which is liquid-tight from the discharge-side umbrella 12 to the communicating hole 42 are formed. For example, the positioning fitting protrusions 40c are fitted into the recessed parts 10a, for example, respectively, so that the blind plate 101 and the pump chamber plate 102 may be integrated in advance, thereby forming the inter-plate suction flow channel 14H and the inter-plate discharge flow channel 15D which are closed therebetween. Lid members other than the blind plate 101 and the pump chamber plate 102 in forming the inter-plate suction flow channel 14H and the inter-plate discharge flow channel 15D are not needed.

As shown in FIG. 7, a sealing ring groove 40b corresponding to (having the same shape in plan view) the sealing ring groove 20b of the lower housing 20 is formed around the recessed part 40a for forming a pump chamber, which faces the piezoelectric vibrator 30, in the pump chamber plate 102. The sealing ring groove 40b is in the shape of a modified letter “D” having a large circular-arc part 40b1 that is a partial circle larger than a semicircle, and a straight part 40b2 whose connects both ends of the large circular-arc part 40b1 together by a straight line.

Both of a unimorph-type piezoelectric vibrator and a bimorph-type piezoelectric vibrator can be used as the piezoelectric vibrator 30. FIGS. 8 to 10 are schematic views of one embodiment of the bimorph-type piezoelectric vibrator, which is proposed in Patent Application No. 2004-192483 by the present applicant. This piezoelectric vibrator is provided with a circular shim 111 at the central part thereof, and piezoelectric elements 112 which are stacked on the front and back thereof. The shim 111 is made of a conductive metallic thin plate material, for example, a stainless steel thin plate having a thickness of about 0.2 mm.

The piezoelectric elements 112 are made of, for example, PZT (Pb(Zr, Ti)O₃) having a thickness of about 3 mm, and they are subjected to polarizing treatment in the direction of the front and back thereof. This polarizing treatment is performed in the same direction in the pair of piezoelectric elements 112 located at the front and back of the shim 111. For example, referring to FIG. 8, when the polarization direction of the pair of piezoelectric elements 112 are denoted by arrow “a” or “b”, the polarizing treatment in the same direction as the thickness direction of the shim 111 is performed. The pair of front and back piezoelectric elements 112 in contact with the shim 111 exhibits polarization characteristics of different poles, respectively, and the exposed surfaces of the pair of piezoelectric elements 112 become different poles, respectively. If the front and back piezoelectric elements 112 are allowed to have the polarization characteristic of the same direction in this way, the displacement of the shim 111 can be increased when positive and negative voltages are applied alternately between the shim 111 and the exposed surfaces of the pair of piezoelectric elements 112 at the front and back of the shim 111.

The whole surfaces of the piezoelectric elements 112 on the side of the pair of shims 111 are adhered to the shim 111 so as to be electrically connected thereto, and a filmy electrode 113 is formed on each of the whole exposed surfaces of the piezoelectric elements opposite to the shim 111. The filmy electrode 113 is formed, for example, by printing (screen-baking) conductive paste (silver paste).

A power supply terminal 180 has a pair of contactors 1811, a connection line 1812 which connects the contactors 1811 to each other, and a wiring connection 1813. The pair of contactors 1811 and the connection line 1812 forms a U-shaped section. The pair of contactors 1811 has the same configuration having a substantially triangular part in plan view that is broader on the side of the wiring connection 1813 located outside the piezoelectric vibrator 30, and becomes gradually narrower toward the central part of the piezoelectric vibrator 30. For example, each contactor 1811 is the narrowest on the side of a part 1131 soldered to the filmy electrode 113 of the piezoelectric vibrator 30, and increases in width toward the outside of the piezoelectric vibrator 30.

A wiring connecting projection 114, which is formed in the shim 111 of the piezoelectric vibrator 30 and projects in the radial direction extends between the pair of contactors 1811. This wiring connecting projection 114 is formed with an insulating recessed part 1141, which ensures a gap from the connection line 1812 that connects the pair of contactors 1811 to each other.

A pair of annular spacer insulating rings 115 are located above and below the circular shim 111, for example, respectively, and striped insulating plate materials 1151 extends to between the pair of contactors 1811 and the wiring connecting projection 114 from the pair of spacer insulating rings 115 so that the short-circuiting between the shim 111 and the power supply terminal 180 can be prevented. Each striped insulating plate material 1151 prevents the connection line 1812 of the power supply terminal 180 from moving toward the insulating recessed part 1141 of the shim 111, thereby ensuring insulation.

The wiring connecting projection 114 of the shim 111 is formed with a pair of lead wire latching recessed parts 1143 and 1144 which are located further outside the piezoelectric vibrator 30 than the insulating recessed part 1141 and which are symmetrical with respect to each other on both sides of the wiring connecting projection 114 in the width direction thereof, and a soldering through hole 1145 is formed inwardly from one lead wire latching recessed part 1143.

The wiring connection 1813 of the power supply terminal 180 is formed with a soldering through hole 1814 corresponding to the soldering through hole 1145 of the wiring connecting projection 114. The soldering through holes 1145 and 1814 are different in positions in plan view, and soldered to lead wires 211 and 221, for example, respectively. Since the soldering through holes 1145 and 1814 increase soldering strength and are made different in positions in plan view, the whole diaphragm pump can be made thin. The lead wires 211 and 221 are hung on the lead wire latching recessed parts 1143 and 1144, thereby increasing resistance against falling-off of the lead wires 211 and 221.

A PPS film (insulating films) 116 (FIG. 8) is adhered to each surface of the piezoelectric vibrator 30. The PPS film 116 has a radial tongue piece 116a which extends onto the power supply terminal 180 to prevent disengagement between the contactors 1811 and the filmy electrode 113 of the piezoelectric vibrator 30.

According to the wiring structure in the vicinity of the wiring connecting projection 114 of the shim 111 and the power supply terminal 180 which have been described hitherto, wiring to the shim 111 and the filmy electrode 113 can be surely attained without obstructing movement of the piezoelectric vibrator 30.

The piezoelectric vibrator 30 whose basic shape is a planar circular shape as described above is sandwiched between the recessed part 20a for forming a pump chamber of the lower housing 20 and the recessed part 40a for forming a pump chamber of the pump chamber plate 102. The upper and lower peripheries of the piezoelectric vibrator are sealed with the sealing rings 16 and 26 to form the pump chambers 13 and 23. The sealing rings 16 and 26 have the same shape as the sealing ring groove 20b of the lower housing 20 and the sealing ring groove 40b of the pump chamber plate 102, and have the large circular-arc part 16a (large circular-arc part 26a) and the straight part 16b (straight part 26b). The power supply terminal 180 of the piezoelectric vibrator 30 is located outside the sealing rings 16 and 26, i.e., outside the straight part 16b (straight part 26b). Since this arrangement prevents intersection of the power supply terminal 180 to the piezoelectric elements 112 of the piezoelectric vibrator 30 with the sealing rings 16 and 26 and local deformation of the sealing rings 16 and 26, the durability can be improved.

The lower housing 20, and the blind plate 101 integrated in advance into the pump chamber plate 102 are combined with each other and integrated into one by fasteners (for example, bolt and nut), with the piezoelectric vibrator 30 sandwiched between the lower housing and blind plate, as described above. In an alternate embodiment, an adhesive can be used additionally.

In the diaphragm pump having the above configuration, when alternating electric fields are applied to between the power supply terminal 180 and the shim 111 (wiring connecting projection 114) to elastically deform (vibrate) the piezoelectric vibrator 30 forward and backward, the volume of one of the pump chambers 13 and 23 increases, and the volume of other one decreases. During the stroke in which the volume of the pump chamber 13 increases, since the suction-side umbrella 11 opens and a fluid flows into the pump chamber 13 from the suction port 31 and simultaneously the volume of the pump chamber 23 decreases, the fluid in the pump chamber 23 opens the discharge-side umbrella (unit) 22, and flows into the discharge port 32.

During the stroke in which the volume of the pump chamber 13 decreases, since the suction-side umbrella (unit) 21 opens and a fluid flows into the pump chamber 23 from the suction port 31, and the volume of the pump chamber 13 decreases, the fluid in the pump chamber 13 opens the discharge-side umbrella 12 and flows into the discharge port 32. The cycle of the pulsation in the discharge port 32 can be shortened (reduced to half as compared with a case where a pump chamber is formed only in one of the upper and lower sides of the piezoelectric vibrator 30). Flow channels of the above-described 4-valve diaphragm pump are skeletonized in FIG. 1.

FIGS. 12 to 14 illustrate an alternate embodiment of the diaphragm pump. The present embodiment is configured such that, even in the seal structure in the vicinity of the inter-plate suction flow channel 14H and the inter-plate discharge flow channel 15D, which are formed between the blind plate 101 and the pump chamber plate 102 (in the upper housing 10), a force in the direction in which the blind plate 101 and are separated from the pump chamber plate 102 is kept from being applied.

For example, instead of the sealing ring groove 14Hc and 15Dc, a pair of recessed groove parts 101b1 and 101b2 are respectively formed around the recessed parts 14Ha and 15Da of the blind plate 101, as shown in the enlarged view of FIG. 13.The pump chamber plate 102 is formed with a pair of elliptical protruding parts 101b1 and 102b1 which are caused to project toward the blind plate 101 and fit into a pair of recessed groove parts 101b1 and 102b2, for example, respectively. When the pair of protruding parts 102b1 and 102b2 and the pair of recessed groove part 101b1 and 101b2 are caused to fit into each other, a pair of closed curve gaps 141c and 142c are formed therebetween.

Sealing rings 141b and 142b are inserted into the pair of closed curve gaps 141c and 142c, for example, respectively. When the sealing rings 141b and 142b are inserted into the pair of closed curve gaps 141c and 142c, a compressive force is generated in the radial direction (the direction in the plane of the blind plate 101 and the pump chamber plate 102). For example, the spaces between the blind plate 101 and the pump chamber plates 102 are held in liquid tightness by the sealing rings 141b and 142b.

The length (thickness) d2 (FIGS. 12 and 13) of the pair of closed curve gaps 141c and 142c in the stacked direction of housings is set to be greater than the thickness (diameter of a section) of the sealing rings 141b and 142b. This length d2 is ensured uniformly. For example, when the pair of protruding parts 102b1 and 102b2 are inserted into the pair of recessed groove parts 101b1 and 101b2, respectively, entrance regulating surfaces 102a1 and 102a2 of the pump chamber plate 102 abut on abutting surfaces 101a1 and 101a2, respectively, thereby regulating the insertion (entrance) position of the protruding parts. The sealing rings 141b and 142b do not receive a compressive force in the stacked direction from the blind plate 101 and the pump chamber plate 102. Any force that makes the blind plate 101 and the pump chamber plate 102 separated in the stacked direction from the sealing ring 141b and 142b is not applied to the blind plate and the pump chamber plate. Since a compressive force that is uniform as a whole is applied to the piezoelectric vibrator 30 from the stacked direction, vibration of the piezoelectric vibrator 30 is also uniformly generated in the stacked direction. The operation of the piezoelectric vibrator 30 can be stabilized, and a fluid can be generated efficiently.

FIGS. 15 to 17 show still another embodiment of the diaphragm pump. This embodiment is an embodiment in which the upper housing 10 is composed of an upper plate 103 and a pair of lid plates 104H and 104D, a suction flow channel 14H1 is formed between this upper plate 103 and the lid plate 104H, and a discharge flow channel 15D1 is formed between the upper plate 103 and the lid plate 104D.

Any force in the direction in which both are separated from each other (force in the direction in which the upper plate 103 and the lid plate 104H (lid plate 104D) are separated from each other) is kept from being applied by the seal structure between the upper plate 103 and the lid plates 104H and between the upper plate 103 and the lid plate 104D. For example, the upper plate 103 is formed with an open suction flow channel groove 103b1 and an open discharge flow channel groove 103b2 whose top are opened. An inside end of the open suction flow channel groove 103b1 is provided with an umbrella 11, and an outside end thereof is provided with a branch channel 41.

Although not shown in FIG. 15, an inside end of the open discharge flow channel groove 103b2 is provided with an umbrella 12, and an outside end thereof is provided with a branch channel 42. Alternatively, the pair of lid plates 104H and 104D is provided with protruding parts 104b1 and 104b2, respectively, which project toward the upper plate 103 and fit into the open suction flow channel groove 103b1 and the open discharge flow channel groove 103b2.

When the protruding parts 104b1 and 104b2 are caused to fit into the open suction flow channel groove 103b1 and the open discharge flow channel groove 103b2, respectively, closed curve gaps 241c and 242c are formed therebetween, as shown in the enlarged view of FIG. 16. The sealing rings 241b and 242b are inserted into the closed curve gaps 241c and 242c, respectively, to form a liquid-tight suction flow channel 14H1 and a liquid-tight discharge flow channel 15D1. When the sealing rings 241b and 242b are inserted into the pair of closed curve gaps 241c and 242c, respectively, a compressive force is generated in the radial direction (the direction in the plane of the pair of lid plates 104H and 104D and the upper plate 103). For example, the spaces between the pair of lid plates 104H and 104D, and the upper plate 103 are held in liquid tightness by the sealing rings.

The length d3 (FIGS. 15 and 16) of the closed curve gaps 241c and 242c in the stacked direction is set to be greater than the thickness (diameter of a section) of the sealing rings 241b and 242b. This length d3 is ensured uniformly. For example, when the pair of protruding parts 104b1 and 104b2 are inserted into the open suction flow channel groove 103b1 and the open discharge flow channel groove 103b2, respectively, entrance regulating surfaces 104a1 and 104a2 of the pair of lid plates 104H and 104D abut on abutting surfaces 103a1 and 103a2, respectively, thereby regulating the insertion (entrance) position of the protruding parts.

The sealing ring 241b or 242b does not receive a compressive force in the stacked direction from the upper plate 103 and the pair of lid plates 104H and 104D. For example, any force that makes the upper plate 103 and the pair of lid plates 104H and 104D separated in the stacked direction from the sealing ring 241b and 242b is not applied to the upper plate and the lid plates. Accordingly, since a compressive force that is uniform as a whole is applied to the piezoelectric vibrator 30 from the stacked direction, vibration of the piezoelectric vibrator 30 is also uniformly generated in the stacked direction. Therefore, the operation of the piezoelectric vibrator 30 can be stabilized, and a fluid can be generated efficiently.

The present embodiments are aimed at the seal structure, which ensures the liquid tightness of the suction flow channel and discharge flow channel of the above embodiment, with high durability. The lower housing, the umbrella, or the piezoelectric vibrator only shows an example. Accordingly, although the umbrella is illustrated as a check valve, check valves other than the umbrella can also be used, and an electrostrictive vibrator may be used instead of the piezoelectric vibrator. Further, the present invention can also be applied to a 2-valve type diaphragm pump, i.e., a pump in which a pump chamber is formed only below a piezoelectric vibrator, and any pump chamber is not provided above the piezoelectric vibrator (an umbrella is not provided).

According to the present embodiments, in a 4-valve diaphragm pump, the liquid tightness of the connecting parts of the flow channels formed over the upper housing and the lower housing can be ensured with high reliability and durability. The liquid tightness of the suction flow channel and discharge flow channel formed in the upper housing can be ensured with high reliability and durability.

Number	Date	Country	Kind
2005-280548	Sep 2005	JP	national
2006-136693	May 2006	JP	national

Diaphragm pump

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CPC

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