Diaphragm pump

Abstract

A diaphragm pump is provided. The diaphragm pump comprises an upper and lower housing, a pump chamber plate, a pair of pump chambers, and a diaphragm that separates the pair of pump chambers. First and second suction-side check valves are disposed between the pair of pump chambers and a suction port. First and second discharge-side check valves are disposed between the pair of pump chambers and a discharge port. The lower housing comprises a first pump chamber concave portion. The pump chamber plate comprises a second pump chamber concave portion, the second suction-side check valve, and the second discharge-side check valve. An interplate suction-side channel and an interplate discharge-side channel are provided between the upper housing and the pump chamber plate.

Description

This application claims the benefit of Japanese Patent App. No. 2005-257376 filed Sep. 6, 2005, which is hereby incorporated by reference.

BACKGROUND

1. Field A diaphragm pump is provided.

2. Related Art

Generally, a diaphragm pump is constructed with pump chambers (variable volume chamber) that are defined by a diaphragm and a pair of check valves having different flow directions that are provided in a pair of channels connected to the pump chamber (a suction-side check valve allowing a flow toward the pump chamber and a discharge-side check valve allowing a flow from the pump chamber are provided in the two channels). To operate the pump, the suction-side check valve opens at a stroke for increasing the volume of the pump chamber by oscillating the diaphragm and the discharge-side check valve opens at a stroke for decreasing the volume of the pump chamber. The diaphragm is made of an elastic (oscillatable) material, for example, a rubber, or a piezoelectric oscillator.

An example of the conventional diaphragm pump is disclosed in Japanese Unexamined Patent Application Publication No. 2001-193656. As described above, the operation of a diaphragm pump is accompanied by pulsation at the discharge port caused by repeating the opening of the suction-side check valve at a stroke that increases the volume of the pump chamber and the opening of the discharge-side check valve at a stroke that decreases the volume of the pump chamber.

A diaphragm pump with a pulsation period at the discharge port is reduced to a half of the pulsation period at the discharge port of the conventional diaphragm pump is disclosed in Japanese Unexamined Patent Application Publication No. 2005-337068. In the diaphragm pump, pump chambers are formed above and under the diaphragm. A single suction port and a single discharge port are installed. First and second suction-side check valves allow fluid to flow from a suction port toward the pair of pump chambers and do not allow fluid to flow in the reverse directions are provided between the pair of pump chambers and the suction port. First and second discharge-side check valves allow fluid to flow from the pair of pump chambers toward the discharge port and does not allow fluid to flow in the reverse directions are provided between the pair of pump chambers and the discharge port (four-valve diaphragm pump).

In addition, a pump structure that enables a slim sized four-valve diaphragm pump is disclosed in Japanese Unexamined Patent Application Publication No. 2005-337068. Umbrellas are attached in the suction and discharge ports formed in the upper and lower housings, respectively, and separate covers are adhered thereto for forming channels. For example, the covers may be adhered by using a highly reliable laser welding. However, over the lifetime of the pump a leak may be caused in a pump by deterioration. It is difficult to obtain perfect reliability.

SUMMARY

In a preferred embodiment, a diaphragm pump includes a pair of pump chambers that are formed by an oscillatable diaphragm above and under the diaphragm. First and second suction-side check valves allow fluid to flow from a suction port toward the pair of pump chambers and do not allow fluid to flow in the reverse directions are provided between the pair of pump chambers and the suction port. First and second discharge-side check valves that allow fluid to flow from the pair of pump chambers toward a discharge port and do not allow fluid to flow in the reverse directions are provided between the pair of pump chambers and the discharge port. The diaphragm pump comprises an upper housing, a pump chamber plate, a diaphragm, and a lower housing, in a sequentially stacked form. The lower housing comprises a first pump chamber that including a concave portion that forms one pump chamber and faces the diaphragm. The suction port includes the first suction-side check valve communicating with the pump chamber forming the concave portion. The discharge port includes the first discharge-side check valve that communicates with the pump chamber concave portion. The pump chamber plate includes a second pump chamber concave portion that forms the other pump chamber and faces the diaphragm, the second suction-side check valve, and the second discharge-side check valve are provided. An interplate suction-side channel that is bifurcated from the second suction-side check valve and connected to the second suction-side check valve and an interplate discharge-side channel that is bifurcated from the second discharge-side check valve and connected to the second discharge-side check valve are provided between the upper housing and the pump chamber plate.

It is desirable that the interplate suction-side channel and the interplate discharge-side channel are sealed by a seal ring inserted between the pump chamber plate and the upper housing.

It is desirable that one end of the interplate suction-side channel and the interplate discharge-side channel communicate with the second suction-side check valve and the second discharge-side check valve, and the other end of the interplate suction-side channel and the discharge-side channel communicate with the channels bifurcated from the suction and discharge ports that open to the lower housing.

When the seal ring has an oval shape, it is easy to form the channel.

It is desirable the first suction-side check valve and the first discharge-side check valve that are provided in the lower housing are formed as a first suction-side check valve unit and a first discharge-side check valve unit that are separate from the lower housing. The first suction-side check valve unit and the first discharge-side check valve unit are attached to pump chamber-side opening ends of the suction and discharge ports. In an alternate embodiment, the first suction-side check valve unit and the first discharge-side check valve unit are provided on the same substrate.

When the suction and discharge ports of the lower housing protrude in parallel with each other in the plane direction of the diaphragm in a free state, it is desirable to obtain a slim diaphragm pump.

According to any embodiments of the present invention, it is desirable that the check valve has an umbrella shape. In addition, it is preferred that the diaphragm is a piezoelectric oscillator or an electrostriction oscillator. Specifically, it is desirable that the diaphragm is a bimorph type piezoelectric oscillator.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an exploded perspective view of an exemplary diaphragm pump according to a preferred embodiment.

FIG. 2 is an exploded cross sectional view of the diaphragm pump shown FIG. 1.

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

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

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

FIG. 6 is a top plan view of an exemplary pump chamber plate side of an upper housing.

FIG. 7 is a top plan view of an exemplary pump chamber that forms a concave portion of a pump chamber plate.

FIG. 8 is an exploded perspective view of an exemplary bimorph type piezoelectric oscillator.

FIG. 9 is a perspective view that illustrates an exemplary relation between the bimorph type piezoelectric oscillator and a deformed D shape seal ring.

FIG. 10 is a top plan view of the same substantial part of FIG. 9.

FIG. 11 is a conceptual view of an exemplary four-valve diaphragm pump according to a preferred embodiment.

DESCRIPTION OF THE PREFERED EMBODIMENTS

The operating mechanism of a four-valve diaphragm pump will be described with reference to FIG. 11. The diaphragm pump includes an upper housing 10, a lower housing 20, a piezoelectric oscillator (diaphragm) 30, and four umbrellas (check valves) 11, 12, 21, and 22. A pump chamber (variable volume chamber) 13 is located between the upper housing 10 and the piezoelectric oscillator 30. A pump chamber (variable volume chamber) 23 is located between the low housing 20 and the piezoelectric oscillator 30.

A single port 31 communicates with the suction-side channels 14H and 24H. The suction-side channel 14H communicates with the pump chamber 13 through the suction-side umbrella 11. The suction-side channel 24H communicates with the pump chamber 23 through the suction-side umbrella 22. In addition, a single discharge port 32 communicates with discharge-side channels 15D and 25D. The discharge-side channel 15D communicates with the pump chamber 13 through a discharge-side umbrella 12. The discharge-side channel 25D communicates with the pump chamber 23 through a discharge-side umbrella 22.

In the four-valve diaphragm pump, when the piezoelectric oscillator 30 is elastically deformed (oscillates) in the forward and backward directions, a volume of one pump chamber 13 or 23 increases and a volume of the other pump chamber 23 or 13 decreases. A stroke for increasing the volume of the pump chamber 13 is a stroke for decreasing the volume of the pump chamber 23. When the volume of the pump chamber 13 increases, the suction-side umbrella (suction-side check valve) 11 opens to introduce a fluid into the pump chamber 13 from the pump port 31, and since the volume of the pump chamber 23 decreases, a fluid in the pump chamber 23 opens the discharge-side umbrella (discharge-side check valve) 22 to discharge the fluid to the discharge port 32.

A stroke that decreases the volume of the pump chamber 13 is a stroke that increases the volume of the pump chamber 23. Since the volume of the pump chamber 23 increases, the suction-side umbrella (suction-side check valve) 21 opens to introduce a fluid into the pump chamber 23 from the suction port 31, and since the volume of the pump chamber 13 decreases, a fluid in the pump chamber 13 opens the discharge-side umbrella (discharge-side check valve) 12 to discharge the fluid to the discharge port 32. Accordingly, the pulsation period at the discharge port 32 can be shortened (the pulsation period is a half of the period in the case where the pump chamber is formed on only one side that is an upper or lower side of the piezoelectric oscillator 30).

According to a preferred embodiment, the four-valve diaphragm pump that operates according to the aforementioned mechanism is embodied as a structure that prevents a leak. An embodiment of the four-valve diaphragm pump will be described with reference to FIGS. 1 to 7.

The diaphragm pump includes the upper housing 10, the lower housing 20, the piezoelectric oscillator 30, and a pump chamber plate 40 attached between the upper housing 10 and the piezoelectric oscillator 30 and has an entirely flattened rectangular shape. The upper housing 10, the lower housing 20, and the pump chamber plate 40 include moldings of resin materials.

The lower housing 20 is the largest molding of the aforementioned moldings. The lower housing 20 is a complex flattened rectangular shape. In the lower housing 20, an opened pump chamber forming concave portion 20a is formed in the opposing surface of the piezoelectric oscillator 30. The suction port 31 and the discharge port 32 are protruded in parallel with each other and integrated with one of the four side faces of the lower housing 20 (refer to FIGS. 1 to 5). In the lower housing 20, the suction-side channel 24H that communicates with the suction port 31 and the discharge-side channel 25D that communicate with the discharge port 32 are formed. Channel expanding portions 24Ha and 25Da communicating with the pump chamber forming concave portion 20a are formed at the inner ends of the suction-side and discharge-side channels 24H and 25D. Valve retainer concave portions 24Hb and 25Db are formed at ends of the channel expanding portions 24Ha and 25Da close to the pump chamber forming concave portion 20a.

A suction-side umbrella unit (suction-side check valve unit) 21U and a discharge-side umbrella unit (discharge-side check valve unit) 22U are adhered and fixed to the valve retainer concave portions 24Hb and 25Db. The suction-side umbrella unit 21U and the discharge-side umbrella unit 22U are the same in the structure, except the attachment direction. An umbrella attaching hole 21c (umbrella attaching hole 22c) is formed on the center portion of the unit plate 21a (unit plate 22a) of which circumference is used as an adhesion portion 21b (adhesion portion 22b) with the valve retainer concave portion 24Hb (valve retainer concave portion 25Db). A plurality of channel holes 21d (channel holes 22d) are formed on the circumference of the umbrella attaching hole 21c (umbrella attaching hole 22c). An umbrella portion 21g (umbrella portion 22g) of an umbrella 21f (umbrella 22f) in which a central axis 21e (central axis 22e) is inserted into the umbrella attaching hole 21c (umbrella attaching hole 22c) covers the channel holes 21d (channel holes 22d).

When pressure greater than a predetermined value is applied to the umbrella portion 21g (umbrella portion 22g) from the channel hole 21d (channel hole 22d), the umbrella portion 21g (umbrella portion 22g) is elastically deformed to open the channel holes 21d (channel holes 22d). The adhesion portion 21b of the suction-side umbrella unit 21U is adhered to the valve retainer concave portion 24Hb. Conversely, the adhesion portion 22b of the discharge-side umbrella unit 22U is adhered to the valve retainer concave portion 25Db. The suction-side umbrella unit 21U allows a flow from the suction port 31 toward the pump chamber forming concave channel portion 20a (pump chamber 23) and does not allow a reverse flow. The discharge-side umbrella unit 22U allows a flow from the pump chamber forming concave portion 20a (pump chamber 23) toward the discharge port 32 and does not allow a reverse flow. The unit plates 21a and 22a of the umbrella units 21U and 22U of the suction and discharge sides may be formed of one substrate.

An additional cover is not needed for the aforementioned lower housing 20. In a body of the lower housing 20, the closed suction-side channel 24H is formed between the suction port 31 and the pump chamber forming concave portion 20a, and the closed discharge-side channel 25D is formed between the discharge port 32 and the pump chamber forming concave portion 20a. In the lower housing 20, a seal ring groove 20b is also formed at the circumference of the pump chamber forming concave portion 20a. The seal ring groove 20b has a deformed D shape that includes a large circular portion 20b1 that exceeds a semicircle and a linear portion 20b2 that connects the both ends of the large circular portion 20b1.

The suction-side umbrella unit 21U and the discharge-side umbrella unit 22U, for example, the valve retainer concave portions 24Hb and 25Db (umbrella portions 21g and 22g) are slanted with respect to the plane of the piezoelectric oscillator 30 (non-parallel). Considering a plane that is perpendicular to the piezoelectric oscillator 30 and contains an axis line of the suction port 31 (discharge port 32), in the plane, the aforementioned slant direction is a direction in which the valve retainer concave portions 24Hb and 25Db and the piezoelectric oscillator 30 become more distant in the rear direction of the suction port 31 (discharge port 32) and become closer in the front direction of the suction port 31 (discharge port 32) to each other.

As described above, when the suction-side and discharge-side umbrella units 21U and 22U are slanted with respect to the piezoelectric oscillator 30, the slim lower housing 20 can be achieved without reducing the cross sections of the channels of the suction and discharge ports 31 and 32.

As shown in FIG. 4, the surface (unit plate 21a of the suction-side umbrella unit 21U (umbrella portion 21g)) of the valve retainer concave portion 24Hb is not in parallel with the surface of the piezoelectric oscillator 30 in a free state and is slanted by an angle of α with respect to the surface of the piezoelectric oscillator 30 in the free state. For example, the channel at the suction-side check valve 21 is not perpendicular to the piezoelectric oscillator 30. On the other hand, the axis line of the suction port 31 (suction-side channel 24H) is in parallel with the surface of the piezoelectric oscillator 30. The direction of the angle of α is a direction in which the unit plate 21a (umbrella portion 21g) of the suction-side umbrella unit 21U becomes spaced apart from the piezoelectric oscillator 30 in the rear direction of the suction port 31 (suction-side channel 24H) and becomes closer to the piezoelectric oscillator 30 in the front direction of the suction port 31 (suction-side channel 24H).

Similarly, as shown in FIG. 5, the surface (unit plate 22a of the discharge-side umbrella unit 22U (umbrella portion 22g)) of the valve retainer concave portion 25Db is not in parallel with the surface of the piezoelectric oscillator 30 and is slanted by an angle of α with respect to the surface of the piezoelectric oscillator 30 in a free state. For example, the channel at the discharge-side check valve 22 is not perpendicular to the piezoelectric oscillator 30. Alternatively, the axis line of the discharge port 32 (discharge-side channel 25D) is parallel with the surface of the piezoelectric oscillator 30. The direction of the angle of α is a direction in which the unit plate 22a (umbrella portion 22g) of the discharge-side umbrella unit 22U becomes apart from the piezoelectric oscillator 30 in the rear direction of the discharge port 32 and becomes closer to the piezoelectric oscillator 30 in the front direction of the discharge port 32 (discharge-side channel 25D).

In the lower housing 20, bifurcated channels 24Hd and 25Dd that are bifurcated from the suction-side channel 24H and the discharge-side channel 25D, respectively, are formed to be opened to the pump chamber plate 40 side. In the pump chamber plate 40, communication holes 41 and 42 communicate with the bifurcated channels 24Hd and 25Dd. An interplate suction-side channel 14H that communicates with the communication hole 41 and an interplate discharge-side channel 15D that communicates with the communication hole 42 are formed between the upper housing 10 and the pump chamber plate 40. For example, in the pump chamber plate 40, convex portions 41a and 42a that are fit into the bifurcated channels 24Hd and 25Dd are formed. The communication holes 41 and 42 are formed at the center of the convex portions 41a and 42a. The reference numerals 41b and 42b indicate o-rings for sealing the bifurcated channels 24Hd and 25Dd with the convex portions 41a and 42a (communication holes 41 and 42).

In the pump chamber plate 40, the pump chamber forming concave portion 40a (FIGS. 2, 4, and 5) faces the piezoelectric oscillator 30. The suction-side umbrella 11 corresponds to the suction-side umbrella unit 21U and the discharge-side umbrella 12 corresponds to the discharge-side umbrella unit 22U that are attached to the approximate center of the pump chamber forming concave portion 40a. The suction-side umbrella 11 and the discharge-side umbrella 12 are not shown in FIG. 2. For example, on the pump chamber plate 40, umbrella attaching holes 11a and 12a are formed under the suction-side umbrella unit 21U and the discharge-side umbrella unit 22U.

A plurality of channel holes 11b and 12b are formed on the circumferences of the umbrella attaching holes 11a and 12a. The suction-side and discharge-side umbrellas 11 and 12 include a central axis 11c (central axis 12c) inserted into the umbrella attaching hole 11a (umbrella attaching hole 12a) and an umbrella portion 11d (umbrella portion 12d) that covers the channel holes 11b (channel holes 12b) in normal times. When pressure greater than a predetermined value is applied to the umbrella portion 11d (umbrella portion 12d) from the channel hole 11b (channel hole 12b) side, the umbrella portion 11d (umbrella portion 12d) is elastically deformed to open the channel holes 11b (channel holes 12b).

The suction-side umbrella 11 allows a flow from the upper housing 10 side toward the pump chamber that forms concave portion 40a (pump chamber 13) and does not allow a reverse flow. The discharge-side umbrella 12 allows a flow from the pump chamber that forms concave portion 40a (pump chamber 13) toward the upper housing 10 side and does not allow a reverse flow.

The upper housing 10 has the same shape as the lower housing 20 so that the upper housing 10 overlaps the lower housing 20. In the upper housing 10, a concave portion 14Ha that forms the interplate suction-side channel 14H that communicates the communication hole 41 with the suction-side umbrella 11 and a concave portion 15Da that forms the interplate discharge-side channel 15D that connects the communication hole 42 to the discharge-side umbrella 12 are formed between the upper housing 10 and the pump chamber plate 40 (refer to FIGS. 2 and 4 to 6).

The seal ring grooves 14Hc and 15Dc that insert oval o-rings (seal rings) 14Hb and 15Db are formed at the circumference of the concave portions 14Ha and 15Da. A concave portion 10a (FIGS. 2 and 6) that inserts the pump chamber plate 40 into the upper housing 10 are formed in the upper housing 10.

A fitting hole 10c and a positioning protrusion 40c (FIG. 1) that fits into the fitting hole 10c while the oval o-rings 14Hb and 15Db are inserted into the concave portions 14Ha and 15Da are formed in the pump chamber plate 40 and the upper housing 10. The positioning protrusion 40c is fitted into the fitting hole 10c and adhered to the fitting hole 10c to form the sealed interplate suction-side channel 14H from the communication hole 41 toward the suction-side umbrella 11 and the sealed interplate discharge-side channel 15D from the communication hole 42 toward the discharge-side umbrella 12. For example, the upper housing 10 and the pump chamber plate 40 are previously integrated with each other by inserting the pump chamber plate 40 into the concave portion 10a to form the interplate suction-side channel 14H and the interplate discharge-side channel 15D that are closed therebetween. An additional cover except the upper housing 10 and the pump chamber plate 40 is not needed for forming the interplate suction-side channel 14H and the interplate discharge-side channel 15D.

As shown in FIG. 7, in the pump chamber plate 40, a seal ring groove 40b (that is the same shape as the seal ring groove of the lower housing 20 on the plane) corresponding to the seal ring groove of the lower housing 20 is formed at the circumference of the pump chamber forming concave portion 40a that faces the piezoelectric oscillator 30. The seal ring groove 40b has a deformed D shape that includes a large circular portion 40b1 that exceeds a semicircle and a linear portion 40b2 that connects both ends of the large circular portion 40b1.

The piezoelectric oscillator 30 may be a unimorph or bimorph type. FIGS. 8 to 10 are pattern diagrams of an embodiment of the bimorph type piezoelectric oscillator disclosed in Japanese Unexamined Patent Application Publication No. 2005-201235. According to the embodiment, the bimorph type piezoelectric oscillator includes a circular shim 111 at the center and piezoelectric members 112 formed over and under the shim 111 by deposition. The shim 111 includes a conductive metal sheet, for example, a stainless steel sheet having a thickness of about 0.2 mm. The piezoelectric member 112 is made of Lead Zirconate Titanate (PZT, Pb(Zr, Ti) O₃). The piezoelectric member 112 is polarized in the front-to-back direction of the piezoelectric members 112. The polarization directions of the pair of piezoelectric members located over the front and back surfaces of the shim 111 are the same.

As shown in FIG. 8, when the polarization direction of the pair of piezoelectric members 112 is represented by the arrow a or b, the piezoelectric members 112 are polarized in the same direction which is the thickness direction of the shim 111. In other words, a pair of the piezoelectric members 112 that are in contact with the front and back surfaces of the shim 111 are polarized to have different poles from each other, at exposed surfaces thereof. The exposed surfaces of the pair of the piezoelectric members 112 are polarized to have different poles from each other. As described above, when the piezoelectric members 112 are polarized in the same direction, the displacement of the shim 111 can be increased when positive and negative voltages are alternately applied between the shim 111 and the surfaces of the pair of the piezoelectric members 112 that face the shim 111.

The surfaces of the pair of the piezoelectric members 112 that face the shim 111 are attached to the shim 111 so as to be entirely electrically conductive to the shim 111. Film shaped electrodes 113 are formed on the surfaces that do not face the shim 111. The film shaped electrodes 113 are formed by printing (screen baking) a conducting paste (silver paste or gold paste).

A supply terminal 180 includes a pair of contacts 1811, a connection edge 1812 for connecting the contacts 1811 with each other, and a wiring connection portion 1813. The pair of contacts 1811 and the connection edge 1812 constitute a U-shaped cross section. The pair of contacts 1811 have a wider width at the wiring connection portion 1813 and have a gradually narrower width toward the center of the piezoelectric oscillator 30 to form the same approximate triangular shapes. For example, the contact 1811 has the narrowest width at the soldering portion 1131 and has a wider width toward the outside of the piezoelectric oscillator 30.

A wiring connection protrusion 114 that is protruded in the diameter direction of the shim 111 of the piezoelectric oscillator 30 is extended between the pair of contacts 1181. In the wiring connection protrusion 114, a concave portion 1141 for insulation for securing a gap between the wiring connection protrusion 114 and the connection edge that connects the pair of contacts 1181 with the wiring connection protrusion 114 is formed.

Annular spacer insulation rings 115 are located over and under the circular shim 111. Strip insulation sheets 1151 are extended from the pair of spacer insulation rings 115 toward between the pair of contacts 1181 and the wiring connection protrusion 114 to prevent a short circuit between the shim 111 and the supply terminal 180. At the same time, the strip insulation sheets 1151 prevent the connection edge 1812 of the supply terminal 180 from moving to the concave portion 1141 of the shim 111 for insulation to secure insulation.

A pair of lead wire holding concave portions 1143 and 1144 are symmetrically formed in the both sides of the wiring connection protrusion 114 in the width direction and located at the outer side of the piezoelectric oscillator 30 as compared with the concave portion 1141 for insulation. A through hole 1145 for soldering is formed at the inner side of the piezoelectric oscillator 30 as compared with the one lead wire holding concave portion 1143.

A through hole 1814 for soldering is formed in correspondence with the through hole 1145 for soldering of the wiring connection protrusion 114 in the wiring connection portion 1813 of the supply terminal 180. The locations of the through holes 1145 and 1814 for soldering are different on the plane, and the lead wires 211 and 221 are soldered into the through holes 1145 and 1814 for soldering. The through holes 1145 and 1814 for soldering are located at different locations on the plane to enable the slim sized diaphragm pump. In addition, the lead wires 211 and 221 are held by the lead wire holding concave portions 1143 and 1144 to increase coming-out stopping resistances of the lead wires 211 and 221.

A PPS film (insulation film) 241 (FIG. 8) is adhered to the surface of the piezoelectric oscillator 30. The PPS film 241 includes a piece 241a in the diameter direction which is extended over the supply terminal 180 to prevent separation between the contacts 1811 and the film shaped electrodes 113 of the piezoelectric oscillator 30.

The shim 111 and the film shaped electrode 113 can be securely wired without disturbing the movement of the piezoelectric oscillator 30 by using the aforementioned connection protrusion 114 of the shim 111 and the wiring structures around the supply terminal 180.

The aforementioned circular piezoelectric oscillator 30 is attached between the pump chamber forming concave portion 20a of the lower housing 20 and the pump chamber forming concave portion 40a of the pump chamber plate 40, and the surroundings are sealed by the seal rings 16 and 26 to form the pump chambers 13 and 23. The seal rings 16 and 26 have the same shape as the seal ring groove 20b of the lower housing 20 and the seal ring groove 40b of the pump chamber plate 40 and include a large circular portion 16a (large circular portion 26a) and a linear portion 16b (linear portion 26b). In addition, the supply terminal 180 of the piezoelectric oscillator 30 is located outside of the seal rings 16 and 26, and more specifically, outside of the linear portion 16b (linear portion 26b). According to the aforementioned layout, the supply terminal 180 for the piezoelectric members 112 of the piezoelectric oscillator 30 need not to cross over the seal rings 16 and 26, and the seal rings 16 and 26 are not deformed, which in turn improves the durability of the piezoelectric oscillator 30.

In addition, the lower housing 20 and the upper housing 10 previously integrated into the pump chamber plate 40 are combined by a fastener (for example, bolts and nuts) to form one body while the piezoelectric oscillator 30 is attached therebetween. Alternatively, an additional adhesive may be used.

The basic operation of the present diaphragm pump having the aforementioned structure is the same as the operation illustrated in FIG. 11. When an alternating electric field is applied between the supply terminal 180 of the piezoelectric oscillator 30 and the shim 111 (wiring connection protrusion 114) to elastically deform (oscillate) the piezoelectric oscillator 30 in forward and backward directions, a volume of one pump chamber 13 or 23 increases and a volume of the other pump chamber 23 or 13 decreases.

In a stroke that increases the volume of the pump chamber 13, since the suction-side umbrella 11 opens to introduce a fluid into the pump chamber 13 from the pump port 31 and the volume of the pump chamber 23 simultaneously decreases, a fluid in the pump chamber 23 opens the discharge-side umbrella (unit) 22 to discharge the fluid to the discharge port 32. In contrast, in a stroke that decreases the volume of the pump chamber 13, since the suction-side umbrella (unit) 21 opens to introduce a fluid into the pump chamber 23 from the suction port 31 and the volume of the pump chamber 13 decreases, a fluid in the pump chamber 13 opens the discharge-side umbrella 12 to discharge the fluid to the discharge port 32.

The seal rings 16 and 26 have a non-circular shape, and alternatively, circular seal rings (o-rings) may be used. In addition, although the umbrella is used as an example of the check valve in the embodiment, it is possible to use another check valve except the umbrella. Although the piezoelectric oscillator is used as the diaphragm in the aforementioned embodiment, it is possible to use an electrostriction oscillator instead of the piezoelectric oscillator.

Claims

1. A diaphragm pump comprising:

an upper and lower housing;

a pump chamber plate;

a pair of pump chambers;

a diaphragm that separates the pair of pump chambers;

first and second suction-side check valves between the pair of pump chambers and a suction port; and

first and second discharge-side check valves between the pair of pump chambers and a discharge port,

wherein the lower housing comprises a first pump chamber concave portion,

wherein the pump chamber plate comprises a second pump chamber concave portion, the second suction-side check valve, and the second discharge-side check valve, and

wherein an interplate suction-side channel and an interplate discharge-side channel are provided between the upper housing and the pump chamber plate.

2. The diaphragm pump according to claim 1, wherein the suction port includes the first suction-side check valve in communication with the first pump chamber forming concave portion, and the discharge port includes the first discharge-side check valve in communication with the first pump chamber forming concave portion.

3. The diaphragm pump according to claim 2, wherein the interplate suction-side channel is bifurcated from the suction port of the lower housing and connected to the second suction-side check valve and the interplate discharge-side channel is bifurcated from the discharge port of the lower housing and connected to the second discharge-side check valve.

4. The diaphragm pump according to claim 3, wherein the interplate suction-side channel and the interplate discharge-side channel are sealed with a seal ring inserted between the pump chamber plate and the upper housing.

5. The diaphragm pump according to claim 4, wherein one end of the interplate suction-side channel and one end of the interplate discharge-side channel communicate with the second suction-side check valve and the second discharge-side check valve, and the other ends of the interplate suction-side channel and the interplate discharge-side channel communicate with the channels bifurcated from the suction and discharge ports that open to the lower housing.

6. The diaphragm pump according to claim 4, wherein the seal ring has an oval shape.

7. The diaphragm pump according to claim 1, wherein the first suction-side check valve and the first discharge-side check valve are formed as a first suction-side check valve unit and a first discharge-side check valve unit that are separate from the lower housing, and the first suction-side check valve unit and the first discharge-side check valve unit are attached to pump chamber-side opening ends of the suction and discharge ports.

8. The diaphragm pump according to claim 7, wherein the first suction-side check valve unit and the first discharge-side check valve unit are provided on the same substrate.

9. The diaphragm pump according to claim 1, wherein the suction and discharge ports of the lower housing are protruded in parallel with each other in the plane direction of the diaphragm in a free state.

10. The diaphragm pump according to claim 1, wherein the check valve has an umbrella shape.

11. The diaphragm pump according to claim 1, wherein the diaphragm is a piezoelectric oscillator or an electrostriction oscillator.

12. The diaphragm pump according to claim 1, wherein the diaphragm is a bimorph type piezoelectric oscillator.