JP2010196492A - Diaphragm pump with valve, and on-off valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diaphragm pump with a valve not causing liquid leakage when driving is stopped. <P>SOLUTION: There is a general knowledge that in the diaphragm pump, it is difficult to prevent the liquid leakage by a check valve only provided in a delivery flow passage during a driving stopped condition not vibrating a diaphragm. Therefore, especially in the delivery flow passage, a normally closed on-off valve is positioned closer to a delivery port than the check valve. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a diaphragm pump that obtains a pumping action by a vibrating diaphragm, and more particularly, to a diaphragm pump with a valve and an on-off valve that can reliably prevent liquid leakage when driving is stopped.

  The present applicant is developing a diaphragm pump (piezoelectric pump) used, for example, as a fuel pump for a fuel cell.

  A piezoelectric pump forms a liquid pump chamber (variable volume chamber) between a plate-shaped piezoelectric vibrator and a housing, and vibrates the piezoelectric vibrator to change the volume of the liquid pump chamber to obtain a pump action. Yes. More specifically, a pair of check valves having different flow directions (a suction side allowing only a fluid flow to the liquid pump chamber) in a pair of flow paths (suction side flow path and discharge side flow path) connected to the liquid pump chamber When the volume of the liquid pump chamber changes due to the vibration of the piezoelectric vibrator, one of the pair of check valves is associated with the check valve and the discharge check valve that allows only fluid flow from the liquid pump chamber. Since the operation of opening the other side is repeated, a pumping action is obtained.

JP 2000-120530 A JP 2005-282387 A JP 2006-224532 A JP 2007-123157 A JP 2008-88904 A

  The pair of check valves of the piezoelectric pump has an action of blocking the liquid flow from the liquid pump chamber to the suction side flow path and the liquid flow from the discharge side flow path to the liquid pump chamber. However, prevention of the fluid flow from the suction side flow path to the liquid pump chamber and the fluid flow from the liquid pump chamber to the discharge side flow path is not necessarily guaranteed. That is, when driving is stopped, the liquid in the liquid pump chamber may leak from the discharge-side flow path. This liquid leakage can be a major problem as fuel leakage when used as a liquid supply pump for a fuel cell.

  Accordingly, an object of the present invention is to provide a diaphragm pump with a valve that does not cause liquid leakage when driving is stopped. In other words, an object of the present invention is to obtain a valved diaphragm pump having a function of stopping liquid feeding when driving is stopped as a single pump.

  The present invention recognizes that in a diaphragm pump, it is difficult to prevent liquid leakage in a drive stop state in which the diaphragm is not vibrated with only a check valve provided in the discharge flow path. A normally-closed on-off valve is provided on the road so as to be positioned closer to the discharge port than the check valve.

  That is, the diaphragm pump with a valve of the present invention includes a housing having a pump chamber formed by a suction port, a discharge port, and a vibrating diaphragm; a pump from the suction port provided in a suction flow path that connects the suction port and the pump chamber. A suction-side check valve that allows only a fluid flow to the chamber; and a discharge-side check valve that allows only a fluid flow from the pump chamber to the discharge port, provided in a discharge channel that connects the discharge port and the pump chamber; In the diaphragm pump having the above, a normally closed on-off valve is provided in the discharge flow channel between the discharge check valve and the discharge port.

  Specifically, the normally-closed on-off valve is a small normally-closed on-off when it is composed of a flexible tube body that constitutes a part of the discharge flow path, and a sleeper projection and a piezoelectric bar that sandwich the tube body. A valve can be constructed. The piezoelectric bar crushes the flexible tube body between the piezoelectric bar and the sleeper projection in a non-energized state to close the flow path, and opens the flow path by the elastic restoring force of the flexible tube body in the energized state.

  The flexible tube body is preferably pressed and deformed by the piezoelectric bar so that the opening cross-sectional area in the state sandwiched between the sleeper projection and the piezoelectric bar is smaller than the opening cross-sectional area in the free state.

  Specifically, the piezoelectric bar can be composed of, for example, a shim bar made of a spring metal material and a piezoelectric body laminated on at least one of the front and back surfaces of the shim bar.

  Specifically, the diaphragm can be constituted by, for example, a piezoelectric vibrator in which a piezoelectric body is laminated on at least one of the front and back sides of a shim made of a conductive metal thin plate.

  It is practical that the housing includes a pair of housings that form a pump chamber by holding the diaphragm in a liquid-tight manner. When the sleeper projection and the piezoelectric bar are provided in one of the pair of housings, the distance between them can be easily set, the structure can be simplified, and the size can be reduced.

  It is practical that the suction side check valve and the discharge side check valve are constituted by umbrellas.

  The open / close valve according to the present invention uses the normally closed open / close valve used in the above-described diaphragm pump with a valve independently, regardless of whether it is normally closed or normally open. The piezoelectric bar has a sleeper projection and a piezoelectric bar for sandwiching the pin, and the opening area of the flexible tube body is changed by changing the distance from the sleeper projection according to the magnitude of the driving voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the diaphragm pump with a pump which can prevent reliably the liquid leakage at the time of a drive stop with the pump single-piece | unit can be obtained.

It is a top view which shows the embodiment which applied this invention to the piezoelectric pump in the state which cut in part. It is sectional drawing which follows the II-II line of FIG. It is sectional drawing which follows the III-III line of FIG. FIG. 4 is a cross-sectional view of the valve closing state taken along line IV-IV in FIGS. 1 and 3. It is sectional drawing of the valve closing state of the flow-path opening-and-closing tube of the normally closed type on-off valve of FIG. FIG. 4 is a cross-sectional view of the valve-open state taken along line IV-IV in FIGS. 1 and 3. It is sectional drawing of the valve opening state of the flow-path opening-and-closing tube of the normally closed type on-off valve of FIG. It is sectional drawing which shows the example of a shape in the free state of the same flow path opening / closing tube.

  In this embodiment, the present invention is applied to a piezoelectric pump 20 with a valve having a piezoelectric vibrator as a vibrating diaphragm. As shown in FIG. 1, the valve-equipped piezoelectric pump 20 includes a substantially rectangular planar housing 21, and a suction port 22 and a discharge port 23 project from the housing 21 so as to constitute a pump as a single unit. As shown in FIGS. 3, 4 and 6, the housing 21 includes upper and lower pump (valve) housings 24 and 25 in the upper part of the figure, and upper and lower flow path housings 26 and 27 in the lower part of the figure. The suction port 22 and the discharge port 23 protrude from the lower flow path housing 27, and a suction flow path 22 a and a discharge flow path 23 a communicating with the suction port 22 and the discharge port 23 are formed in the lower flow path housing 27. .

  As shown in FIG. 1, the end portion of the suction flow path 22a communicates with circular suction flow path holes 26a and 25a formed in the upper flow path housing 26 and the lower pump housing 25 so as to match the planar positions. Similarly, the end portion of the discharge channel 23a communicates with the circular discharge channel holes 26b and 25b.

  A piezoelectric vibrator (diaphragm) 28 is sandwiched and supported between the upper pump housing 24 and the lower pump housing 25 via an O-ring 29 as shown in FIG. And the lower pump housing 25 constitute a pump chamber P. An atmospheric chamber A is formed between the piezoelectric vibrator 28 and the upper pump housing 24. In this embodiment, the axes of the circular suction passage hole 26a (25a) and the circular suction passage hole 26b (25b) and the piezoelectric vibrator 28 are in a positional relationship orthogonal to each other.

  The upper and lower flow path housings 26 and 27 are welded or bonded with an O-ring or a laser (not shown) except for the openings to ensure sealing performance. More specifically, the outlet side of the valve is an O-ring or laser welding (not shown), and the inlet side of the valve is an O-ring or laser welding on both sides of the discharge channel 23a provided in the groove shape in the lower channel housing 27. And seal. Further, the suction flow path 22a forms a discharge flow path 23a with a tunnel-like hole provided in the lower flow path housing from the suction port 22 to the first bend point, and the discharge flow path after the first bend point is a circular suction flow. Sealing is performed by an O-ring connecting to the passage hole 26a or laser welding.

The piezoelectric vibrator 28 is a unimorph type having a shim 28a at the center and a piezoelectric body 28b formed on the front and back surfaces of the shim 28a (upper surface in FIG. 2). The shim 28a is made of a conductive metal thin plate material, for example, a metal thin plate formed of stainless steel having a thickness of about 50 to 300 μm, 42 alloy, or the like. The piezoelectric body 28b is made of, for example, PZT (Pb (Zr, Ti) O ₃ ) having a thickness of about 300 μm, and is polarized in the front and back directions. Such a piezoelectric vibrator is well known.

  The circular suction passage hole 26a (25a) and the circular discharge passage hole 26b (25b) of the lower pump housing 25 are positioned on the pump chamber P side and the discharge passage side, respectively, and check valves (umbrellas) 32 and 33, respectively. Is provided. The check valve 32 is a suction-side check valve that allows a fluid flow from the circular suction passage hole 26a (25a) to the pump chamber P and does not allow the reverse fluid flow. The check valve 33 is a pump chamber. This is a discharge-side check valve that allows fluid flow from P to the circular suction passage hole 26b (25b) but does not allow the reverse fluid flow. Further, the circular suction flow passage hole 26a (25a) and the circular discharge flow passage hole 26b (25b) are formed over the lower pump housing 25 and the upper flow passage housing 26. It is desirable to seal with a ring or weld by means such as a laser.

  The check valves 32 and 33 have the same configuration, and are provided with umbrellas 32b and 33b made of an elastic material on perforated substrates 32a and 33a that are bonded and fixed to the flow path. Such a check valve (umbrella) itself is well known. The perforated substrates 32 a and 33 a are formed separately in the present embodiment, but may be formed integrally with the lower pump housing 25.

  The discharge flow path 23 a formed in the lower flow path housing 27 is connected to the branched flexible tube body 40 from the discharge side check valve 33 to the discharge port 23. That is, as shown in FIGS. 3 and 1, the lower pump housing 25 is formed with a pair of flow path protrusions 25c extending into the valve storage space 24a of the upper pump housing 24, and the pair of flow path protrusions 25c. However, it communicates with the discharge flow path 23 a through the pair of communication holes 25 d of the lower pump housing 25 and the pair of communication holes 26 c of the upper flow path housing 26. The pair of flow path protrusions 25c are connected by a flexible tube body 40 that constitutes a part of the discharge flow path. The pair of communication holes 25d and 26c are provided over the lower pump housing 25 and the upper flow path housing. However, in order to maintain sealing performance, the communication holes 25d and 26c are sealed with an O-ring (not shown) or welded by means such as laser. It is desirable to do.

  On the other hand, the lower pump housing 25 is provided with a sleeper projection 41 having a semicircular cross section for sandwiching the flexible tube body 40 and a piezoelectric bar (plate) 42 in a positional relationship orthogonal to the flexible tube body 40. Yes. The piezoelectric bar 42 has elasticity that deforms toward the sleeper projection 41 and crushes the flexible tube body 40 in a non-energized state, and crushes and deforms the flexible tube body 40 depending on the magnitude of the energized voltage in the energized state. The force is decreased, the flexible tube body 40 is restored by its elastic restoring force and the discharge pressure from the pump chamber P, and the flow path is opened. That is, the flexible tube body 40, the sleeper projection 41, and the piezoelectric bar 42 constitute a normally closed on-off valve.

  FIG. 8 shows an example of a cross-sectional shape in the free state of the flexible tube body 40 before and after the sandwiched portion of the sleeper projection 41 and the piezoelectric bar 42. The flexible tube body 40 is made of a molded product of a synthetic resin material, and its outer cross-sectional shape is an elliptical shape 40X, while its inner cross-sectional shape is a non-elliptical shape. In other words, the inner cross-sectional shape is obtained by continuing a pair of outer shape transition shapes 40Y obtained by moving the outer shape ellipse 40X in parallel with the thickness in the minor axis Y direction at a portion intersecting the major axis X. The intersecting part has a sharp shape. By setting the cross-sectional shape of the flexible tube body 40 in this manner, liquid leakage at both edges can be eliminated when the flexible tube body 40 is crushed in the minor axis Y direction. In addition, since the elliptical shape 40X and the outer shape transition shape 40Y are parallel and the thickness of the thick portion when the opening is closed is constant, the major axis X is generally parallel to the minor axis Y direction. Therefore, the flexible tube body 40 can be reliably closed with a small force.

As shown in FIGS. 3, 4, and 6, the piezoelectric bar 42 includes a spring metal material shim bar (plate) 42 a at the center and piezoelectric bodies 42 b that are laminated and bonded to the front and back of the shim bar 42 a. Both ends thereof are fixed to a pair of fixing seats 43 formed in the lower pump housing 25 by fixing screws 44. The shim bar 42a may be composed of, for example, 42 alloy having a thickness of about 300 μm, and the piezoelectric body 42b may be composed of, for example, PZT (Pb (Zr, Ti) O ₃ ) having a thickness of about 300 μm. The polarization directions of the front and back piezoelectric bodies 42b are the same. The piezoelectric bar 42 connects the shim bar 42a to one electrode, connects the exposed surface of the front and back piezoelectric bodies 42b (surface opposite to the shim bar 42a) to the other common electrode, and connects the front and back piezoelectric bodies 42b. By applying the driving voltage, the driving voltage can be changed so as to move toward and away from the sleeper projection 41.

  In this embodiment, when the both ends of the piezoelectric bar 42 are fixed on the fixing seat 43 with the fixing screw 44, and the driving voltage is not applied to the piezoelectric body 42b, the flexible tube body 40 is completely formed as shown in FIGS. The free shape and the fixing mode are set so that the flow path (discharge flow path) is closed. When a driving voltage is applied to the front and back piezoelectric bodies 42b, the piezoelectric bar 42 is deformed in a direction away from the flexible tube body 40, and between the pair of outer shape transition shapes of the flexible tube body 40 as shown in FIGS. There is a gap in the channel and the flow path opens. It is known that the piezoelectric bar 42 is displaced substantially in proportion to the drive voltage. Therefore, the opening degree can be adjusted and the flow rate can be controlled by controlling the drive voltage. In both the valve-closed state and the valve-opened state, the flow passage cross-sectional area of the flexible tube body 40 by the pair of outer shape transition shapes 40Y is smaller than the flow passage cross-sectional area of the flexible tube body 40 in the free state (the flexible tube body 40 is In the installed state sandwiched between the sleeper projection 41 and the piezoelectric bar 42, it is crushed).

  The operation of the piezoelectric pump with a valve 20 having the above-described configuration is as follows. When the piezoelectric vibrator 28 is elastically deformed (vibrated) in the forward and reverse directions, the suction side check valve 32 is opened and the discharge side check valve 33 is closed in the process of expanding the volume of the pump chamber P. The liquid flows into the pump chamber P from the flow path 22a and the circular suction flow path hole 26a (25a). On the other hand, in the process of reducing the volume of the pump chamber P, the discharge-side check valve 33 is opened and the suction-side check valve 32 is closed, so that the circular suction channel hole 26b (25b) and the discharge channel 23a from the pump chamber P. The liquid flows out to the discharge port 23. Accordingly, the pump action is obtained by elastically deforming (vibrating) the piezoelectric vibrator 28 continuously in the forward and reverse directions.

  In this pump drive state, a predetermined drive voltage is also applied to the piezoelectric body 42b of the piezoelectric bar 42. Then, the piezoelectric bar 42 is elastically deformed in a direction away from the sleeper projection 41 and the flexible tube body 40 is opened (FIGS. 6 and 7), so that it can be used without any problem as a liquid feed pump of a fuel cell, for example. If necessary, the opening degree of the flexible tube body 40 can be changed by a driving voltage applied to the piezoelectric body 42b.

  A more important function of the piezoelectric pump 20 with a valve is a pump stop state. In the pump stop state, the application of the drive voltage to the piezoelectric bar 42 is also stopped. Then, since the piezoelectric bar 42 is pressed against the sleeper projection 41 and closes the flexible tube body 40 (FIGS. 4 and 5), the liquid in the pump chamber P passes through 33 to the discharge channel 23a (discharge port 23). There is no leakage.

  Further, as in the above embodiment, the sleeper projection 41 for sandwiching the flexible tube body 40 on one of the upper and lower pump housings 24, 25 (lower pump housing 25 in the illustrated example), the piezoelectric bar (plate) 42, The distance between the sleeper projection 41 and the piezoelectric bar 42 can be set easily and strictly. In theory, however, the sleeper projection 41 and the piezoelectric bar 42 can be provided on one and the other of the upper and lower pump housings 24 and 25.

  In the embodiment of the piezoelectric pump with valve 20 described above, the valve formed of the flexible tube 40, the sleeper projection 41, and the piezoelectric bar 42 is used as a normally closed type. However, as described above, it is known that the piezoelectric bar 42 is displaced in proportion to the drive voltage. Therefore, only the valve by the flexible tube 40, the sleeper projection 41 and the piezoelectric bar 42 is taken out, and the open / close valve ( It can be used as a flow control valve. In this aspect, it is possible to adjust the flow rate by gradually closing the flow path by applying a driving voltage to the piezoelectric body 42b of the piezoelectric bar 42, which is normally open.

  In the above embodiment, the bimorph type is shown as the piezoelectric bar 42, but a unimorph type can also be used. On the contrary, the unimorph type piezoelectric vibrator 28 is exemplified as the diaphragm, but a bimorph type piezoelectric vibrator can also be used. Further, the positions of the shim 28a and the piezoelectric body 28b of the unimorph type piezoelectric vibrator 28 can be reversed. Further, in the above embodiment, the present invention is applied to a two-valve type diaphragm pump in which the pump chamber P is formed only on one surface of the piezoelectric vibrator 28. However, a diaphragm pump of a type in which the pump chamber is formed on both surfaces. In addition, the present invention is applicable. Furthermore, the present invention can be applied to a diaphragm pump in general that obtains a pump action by periodically changing the volume of the pump chamber to be larger or smaller by vibration of the diaphragm. Moreover, although the diaphragm pump with a valve | bulb of this invention is suitably used as a liquid feed pump of a fuel cell, it does not limit an application.

20 Piezoelectric pump with valve 21 Housing 22 Suction port 22a Suction flow path 23 Discharge port 23a Discharge flow path 24 Upper pump housing 24a Valve storage space 25 Lower pump housing 25a Circular suction flow path hole 25b Circular discharge flow path hole 25c Flow path protrusion 25d Communication hole 26 Upper flow path housing 26a Circular suction flow path hole 26b Circular suction flow path hole 26c Communication hole 27 Lower flow path housing 28 Piezoelectric vibrator (diaphragm)
28a shim 28b piezoelectric body 29 O-ring 32 suction side check valve 33 discharge side check valve 40 flexible tube body 40X elliptical shape 40Y outer shape transition shape 41 sleeper projection 42 piezoelectric bar 42a shim bar 42b piezoelectric body 43 fixing seat 44 fixing screw P pump Room

Claims (10)

A housing having a suction chamber, a discharge port and a pump chamber formed by a vibrating diaphragm;
A suction-side check valve that allows only a fluid flow from the suction port to the pump chamber, provided in a suction flow path that connects the suction port and the pump chamber;
A discharge-side check valve that allows only a fluid flow from the pump chamber to the discharge port; and a discharge-side check valve and a discharge that are provided in a discharge flow path that connects the discharge port and the pump chamber; A normally-closed on-off valve located between the port;
A diaphragm pump with a valve, characterized by comprising: 2. The diaphragm pump with a valve according to claim 1, wherein the normally closed on-off valve comprises a flexible tube body constituting a part of the discharge flow path, a sleeper projection and a piezoelectric bar sandwiching the tube body. The piezoelectric bar is a diaphragm pump with a valve that closes the flow path by crushing the flexible tube body between the piezoelectric bar and the sleeper projection in a non-energized state, and opens the flow path by the elastic restoring force of the flexible tube body in the energized state. 3. The diaphragm pump with a valve according to claim 2, wherein the flexible tube body is piezoelectric so that an opening cross-sectional area in a state sandwiched between sleeper protrusions and a piezoelectric bar is smaller than an opening cross-sectional area in a free state. Diaphragm pump with a valve that is pressed and deformed by a bar. 4. The diaphragm pump with a valve according to claim 2, wherein the piezoelectric bar includes a shim bar made of a spring metal material and a piezoelectric body laminated on at least one of the front and back surfaces of the shim bar. The diaphragm pump with a valve according to any one of claims 1 to 4, wherein the diaphragm is a piezoelectric vibrator in which a piezoelectric body is laminated on at least one of the front and back of a shim made of a conductive metal thin plate. The diaphragm pump with a valve according to any one of claims 2 to 5, wherein the housing includes a pair of housings that form a pump chamber by sandwiching and holding the diaphragm in a liquid-tight manner, The piezoelectric bar is a diaphragm pump with a valve provided on one of the pair of housings. The diaphragm pump with a valve according to any one of claims 1 to 6, wherein the suction-side check valve and the discharge-side check valve are umbrellas. A flexible tube body, and a sleeper projection and a piezoelectric bar for sandwiching the tube body, and the piezoelectric bar has an opening of the flexible tube body by changing a distance from the sleeper projection according to the magnitude of the driving voltage. An open / close valve characterized by changing the area. 9. The on-off valve according to claim 8, wherein the flexible tube body is formed by a piezoelectric bar so that an opening cross-sectional area in a state sandwiched between a sleeper projection and a piezoelectric bar is smaller than an opening cross-sectional area in a free state. An open / close valve that is deformed by pressure. 10. The on-off valve according to claim 8, wherein the piezoelectric bar includes a shim bar made of a spring metal material and a piezoelectric body laminated on at least one of the front and back sides of the shim bar.

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