This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2014-192996, filed Sep. 22, 2014, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate to a check valve mechanism and a pump device using the same.
Some of existing small diaphragm pumps use, for example, a vibrator consisting of a piezoelectric element (hereinafter referred to as a ‘piezoelectric vibrator’). In a small diaphragm pump using a piezoelectric vibrator, the external circumferential part of the piezoelectric vibrator is hermetically supported on the internal circumferential surface of the housing of the small diaphragm pump. The piezoelectric vibrator is vibrated when applied with an alternating voltage. In this way, the internal capacity of the housing is periodically changed by curving the piezoelectric vibrator. In this case, the conveyed fluid is sucked into a pump chamber from a suction opening by a suction-side check valve, and the fluid in the pump chamber is discharged from a discharge opening through a discharge-side check valve.
Generally, in a small diaphragm pump using a piezoelectric vibrator, only a small amount of conveyed fluid is discharged at a time. Thus, a check valve needs to be actuated by a tiny pressure difference. Moreover, it is required that the check valve is opened under a set desirable differential pressure for forward flow and that reverse flow is prohibited.
In existing small diaphragm pumps, as an example, the suction-side check valve or the discharge-side check valve is an umbrella-type valve made from a flexible elastic rubber material such as silicone rubber, butyl rubber or fluoro rubber.
Further, as another example, a small diaphragm pump also uses a seat valve which is substantially formed into an L shape by a fixed base end and a movable tongue piece extending from the base end. The seat valve is integrally made from, for example, a rubber material having elasticity or a synthetic resin material.
In accordance with an embodiment, a check valve mechanism comprises a sealing case, a sheet component, a sheet-shaped valve body and a load adding mechanism. The sealing case has a suction opening for liquid and a discharge opening for liquid and an internal flow path connecting the suction opening with the discharge opening. The sheet component which is located at the downstream side of the suction opening and fixed on the sealing case by covering the periphery of the suction opening is made from a resin material having an opening at a position corresponding to the suction opening. The sheet-shaped valve body is arranged at the downstream side of the sheet component and made from a resin material having a blocking area for blocking the opening of the sheet component. The load adding mechanism is arranged at the downstream side of the sheet-shaped valve body to add a load for the blocking area of the sheet-shaped valve body towards the sheet component.
As shown in
A suction opening 10, a concentric circular recess 11 and an annular groove 12 outside of the circular recess 11 are arranged on the base plate 8 of the main case body 7. An adhesion area 13 for the adhesion of the sheet component 4 is formed between the circular recess 11 and the annular groove 12. A notch section 14 for positioning the sheet component 4 is formed on a part of the circumferential wall of the main case body 7. A stepped shape fitting recess 15 is formed on the internal side of the opened surface of the main case body 7.
The second sealing case 3 comprises a main case body 16 substantially in a rectangular plate shape and a cylindrical discharge opening body 17 protruded in the center of the main case body 16. As shown in
Then, as shown in
Further, in the second sealing case 3, a circular recess 22 is formed on the front end surface of the insertion protrusion 19. An X-shaped groove 23 substantially in an X shape is formed around the inlet 18a of the discharge opening 18 on the internal bottom side of the circular recess 22.
The sheet component 4 is a rectangular plate sheet which substantially has the same size with the rectangular frame of the main case body 7 of the first sealing case 2. The sheet component 4 which is made from a resin material such as polyimide has a thickness of 25 um and a vertical elastic coefficient (Young's modulus) of 2-4 GPa, and preferably, 3 GPa. The sheet component 4 has a circular opening 4a which is formed at a position corresponding to the suction opening 10. Moreover, an engagement protrusion 4b corresponding to the notch section 14 of the main case body 7 of the first sealing case 2 is formed on the periphery of the sheet component 4.
Then, the sheet component 4 is positioned at the downstream side of the suction opening 10 of the first sealing case 2 and fixed on the first sealing case 2 by covering the periphery of the suction opening 10. In the embodiment, an adhesive is coated on the adhesion area 13 of the first sealing case 2 to adhesively fix the sheet component 4 on the adhesion area 13. Thus, as shown in
Further, as the adhesive also contains a material solidified through heat burning, the sheet component 4, if burnt at a high temperature and then cooled to the normal temperature, may deform because of the difference of coefficients of linear expansion. Particularly, in the case where the first sealing case 2 is greater in coefficient of linear expansion than the sheet component 4 having an opening 4a, the sheet component 4 having the opening 4a, if burnt at a high temperature and then cooled to the normal temperature, is bent and therefore hardly usable. Thus, it is preferred that the coefficient of linear expansion of the sheet component 4 having the opening 4a is equal to or greater than that of the first sealing case 2. In the case where the coefficient of linear expansion of the first sealing case 2 is smaller than that of the sheet component 4 having the opening 4a, the first sealing case 2, if burnt at a high temperature and then cooled to the normal temperature, applies a force for stretching the sheet component 4 having the opening 4a. Further, not limited to be fixed on the first sealing case 2 through adhesive fixation, for example, the sheet component 4 may also be fixed on the first sealing case 2 using a fixation method not allowing the inflow/outflow of a fluid, for example, a thermal welding method.
Further, the opening 4a and the external shape of the sheet component 4 may be formed using a punching die, a thomson die or a pinnacle die. In the case of the use of a punching die, burr 4c (refer to
The sheet-shaped valve body 5 which is located at the downstream side of the sheet component 4 is made from a resin material having a blocking area 5a for blocking the opening 4a of the sheet component 4. Openings for the flow of a fluid, that is, eight holes 5b in the embodiment, are formed around the blocking area 5a of the sheet-shaped valve body 5. The sheet-shaped valve body 5 is made from the same material with the sheet component 4, in other words, formed to have the same Young's modulus and the same thickness with the sheet component 4. In the embodiment, the sheet-shaped valve body 5 is made from a resin material such as polyimide and has a thickness of 25 um a vertical elastic coefficient (Young's modulus) of 2-4 GPa, and preferably, 3 GPa.
The load adding mechanism 6 is located at the downstream side of the sheet-shaped valve body 5 to add, for the blocking area 5a of the sheet-shaped valve body 5, a load towards the sheet component 4. In the embodiment, the load adding mechanism 6 mainly comprises a pressing component 24 and a spring component 25. The pressing component 24 has an arc-shaped pressing section 24b on the front end of a shaft 24a, wherein the arc-shaped pressing section 24b is integrally made from a resin material such as PPS. The spring component 25 is composed of a sheet-shaped vortex spring made from nickel plated stainless steel. A hole 25b through which the shaft 24a of the pressing component 24 is inserted is formed in the center of the rectangular base plate 25a of the spring component 25. The internal ends of a plurality of gyrate arms 25d, three gyrate arms 25d in the embodiment, are connected with the periphery of an engagement ring around the hole 25b.
To assemble the load adding mechanism 6, the shaft 24a of the pressing component 24 is inserted through the hole 25b of the engagement ring 25c of the spring component 25 with the pressing section 24b of the pressing component 24 opposite to the blocking area 5a of the sheet-shaped valve body 5. Under this state, the first sealing case 2 and the second sealing case 3 are assembled by adding a load for the blocking area 5a of the sheet-shaped valve body 5 towards the sheet component 4 using the load adding mechanism 6. That is, when the first sealing case 2 and the second sealing case 3 are assembled, the periphery of the base plate 25a of the spring component 25 is pressed to the side of the first sealing case 2 through the periphery of the circular recess 22 on the front end of the insertion protrusion 19 of the second sealing case 3. In this case, as the pressing section 24b of the pressing component 24 collides with the blocking area 5a of the sheet-shaped valve body 5, the engagement ring 25c is motionless. Thus, the pressing force of the insertion protrusion 19 of the second sealing case 3 applied to the spring component 25 acts on the periphery of the base plate 25a of the spring component 25, the three gyrate arms 25d are elastically deformed in a stretched manner under the pressing force. Then, if the first sealing case 2 and the second sealing case 3 are assembled to correct assembly positions, then, as shown in
(Effect)
The effect of the foregoing structure is described below.
Further, when the sheet component 4 having the opening 4a is made from a thicker member or a harder material, the sheet component 4 having the opening is linearly contacted with the sheet-shaped valve body 5. Thus, for example, if the edge of the sheet component 4 is damaged, then leakage occurs from the damaged part, making it impossible to give play to a unidirectional performance. In the embodiment, the sheet-shaped valve body 5 and the sheet component 4 are curved to the same extent in the part extending to the inside of the circular recess 11, thus, the sheet component 4 can be in surface contact with the sheet-shaped valve body 5 to prevent the foregoing situation.
In the check valve mechanism 1 of the first embodiment, the part of the sheet component 4 having the opening 4a which is not adhesively fixed, that is, the part of the sheet component 4 extending into the circular recess 11 (the part covering the suction opening 10), can transfer a pressure. Thus, the area of the diameter D1 of the circular recess 11 shown in
(Effect)
Thus, the check valve mechanism 1 with the foregoing structure has the following effect: function as a check valve mechanism 1 which has a high unidirectional performance even if the check valve mechanism 1 uses no component having a small longitudinal elastic coefficient (Young's modulus) (made from rubber). As the opening of the check valve mechanism 1 is determined by balancing the pressure applied to the part of the sheet component 4 having the opening 4a which is not adhesively fixed, that is, the area of the sheet component 4 extending to the internal diameter D1 of the circular recess 11 and the load adding mechanism 6, the check valve mechanism 1 can function under a tiny differential pressure. Further, the load of the load adding mechanism 6 can be increased, thus, the sealing property and the stability of the opening 4a of the sheet component 4 and the sheet-shaped valve body 5 can be improved.
Thus, a high unidirectional performance can be achieved even in the use of a component made from a material having a small longitudinal elastic coefficient, for example, rubber, the check valve mechanism 1 can function under a tiny differential pressure. Further, with a desirable chemical resistance, the sealing property of the opening 4a of the sheet component 4 and the sheet-shaped valve body 5 is improved, and the stability of the check valve mechanism 1 is also improved.
Further, if the flux from the suction opening 10 of the first sealing case 2 is large, it is considered to curve the spring component 25 of the load adding mechanism 6 considerably, as shown in
[A Pump Device Using the Check Valve Mechanism 1 of the First Embodiment]
The pump chamber 35 has a recess part 40 which is formed on an end surface of the housing 32. The opening of the recess part 40 is blocked by a piezoelectric diaphragm 41. The piezoelectric diaphragm 41 comprises a resin diaphragm 42 and a piezoelectric vibrating plate 43 adhered on the diaphragm 42. The piezoelectric vibrating plate 43 is vibrated repeatedly by a drive source (not shown), the adhered diaphragm 42 is vibrated repeatedly as well, thus, the piezoelectric diaphragm 41 is wholly vibrated repeatedly.
Further, the suction-side check valve 36 is arranged at the side of the suction opening 38 of the pump chamber 35, and the discharge-side check valve 37 is arranged at the side of the discharge opening 39 of the pump chamber 35. The suction-side check valve 36 and the discharge-side check valve 37 are structurally identical to the check valve mechanism 1 of the first embodiment. Here, the suction-side check valve 36 is provided with a first sealing case 2 on the side of the suction flow path 33 and a second sealing case 3 on the side of the pump chamber 35. Then, the conveyed fluid flowing from the suction flow path 33 passes the suction-side check valve 36 and then flows to the side of the pump chamber 35. Contrarily, the flow of the conveyed fluid from the pump chamber 35, through the suction-side check valve 36, to the suction flow path 33 is prevented. In this way, the reverse flow of the conveyed fluid coming from the suction-side check valve 36 is prevented.
Further, the discharge-side check valve 37 is provided with a first sealing case 2 at the side of the pump chamber 35 and a second sealing case 3 at the side of the discharging flow path 34. Then, the conveyed fluid flows from the pump chamber 35, through the discharge-side check valve 37, to the discharging flow path 34. Contrarily, the flow of the conveyed fluid from the discharging flow path 34, through the discharge-side check valve 37, to the side of the pump chamber 35 is prevented. In this way, the reverse flow of the conveyed fluid discharged from the discharge-side check valve 37 is prevented.
Then, when the pump device is driven, the piezoelectric diaphragm 41 is vibrated repeatedly to suck the conveyed fluid in and eject the conveyed fluid out. At this time, as indicated by the solid arrow shown in
In the pump device 31 of the embodiment, the check valve mechanism 1 of embodiment functions as the suction-side check valve 36 and the discharge-side check valve 37. Thus, like the check valve mechanism 1 of embodiment, the pump device can achieve a high unidirectional performance even in the use of a component made from a material having a small longitudinal elastic coefficient, for example rubber, and can function under a tiny differential pressure. Further, with a desirable chemical resistance, the sealing property of the opening 4a of the sheet component 4 and the sheet-shaped valve body 5 is improved, and the stability of the pump device 31 is also improved.
A stepped hole 18b having a larger internal diameter than the outlet part 18c of the discharge opening 18 is formed on the internal circumferential surface of the discharge opening 18 in the discharge opening body 17 of the second sealing case 3. The stepped hole 18b and the stepped part of the jointing section of the outlet part 18c function as a spring seat surface 54 of the compression spring 52. A changable gap is reserved between the internal diameter of the stepped hole 18b and the external diameter of the compression spring 52.
The compression spring 52 is inserted by being clamped between the stepped hole 18b of the second sealing case 3 and the external circumferential surface of the shaft 24a of the pressing component 24. Then, one end of the compression spring 52 is propped against the spring seat surface 54 and the other end of the compression spring 52 is propped against the back side of the pressing section 24b of the pressing component 24. In this way, the compression spring 52 presses the blocking area 5a of the sheet-shaped valve body 5 towards the sheet component 4.
As shown in
(Function•Effect) In the embodiment, a load adding mechanism 53 using a coiled type compression spring 52 is arranged. Under the pressing force of the compression spring 52, the pressing component 24 presses the blocking area 5a of the sheet-shaped valve body 5. The pressing force becomes a spring force by means of which the load adding mechanism 53 adds a load for the blocking area 5a of the sheet-shaped valve body 5 towards the side of the sheet component 4. Thus, the embodiment can achieve the same effect with the check valve mechanism 1 of the first embodiment (refer to
Further, in the embodiment, as a cross-shaped rib 55 is arranged on the external circumferential surface of the shaft 24a of the pressing component 24, a gap can be set between the shaft 24a of the pressing component 24 and the discharge opening 18. Thus, an adequate flow path opening can be set at the discharge opening 18 to reduce the resistance of the flow path.
(Function•Effect)
In the third embodiment, the cylindrical discharge opening body 62 is arranged on the first sealing case 2, as the discharge opening 18 is arranged on the discharge opening body 62, fluid can flow into the space between the suction opening 10 and the discharge opening 18 merely from one direction.
According to the foregoing embodiments, a check valve mechanism and a pump device using the same are provided which show a high unidirectional performance even in the use of a component made from a material having a small longitudinal elastic coefficient, for example, rubber, function even under a tiny differential pressure and, with an excellent chemical resistance, is improved in the sealing property of the opening of the sheet component and the sheet-shaped valve body and stability.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the invention. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the invention.
Number | Date | Country | Kind |
---|---|---|---|
2014-192996 | Sep 2014 | JP | national |