Diaphragm with edge seal

Abstract

A diaphragm (18) includes a disk-shaped center planar portion (40) and a first lip (42) and a second lip (44) on the outermost edge of the disk shaped portion (40) and extending transversely to the planar disk portion (40). The first lip (42) is on a first side of the diaphragm (18) and the second lip (44) is on an opposite side of the diaphragm (18). A mounting portion (38) extends outward from the center of the face of the planar portion (40) on the first side of the diaphragm (18). For metering pump applications pumping harsh fluids, the diaphragm (18) is typically made from a fluoropolymer and in particular may be made from polytetrafluoroethylene (PTFE).

Claims

1. A diaphragm assembly comprising: a diaphragm member comprising: a disk shaped portion having a first face and an opposed second face; a first edge portion extending substantially transverse to the first face of the disk shaped portion; a second edge portion extending substantially transverse to the second face of the disk shaped portion; a frame configured to support and seal a periphery of the diaphragm member, the frame having first and second clamping faces engaging the first and second faces of the diaphragm member and defining a cavity configured to receive the first edge portion and the second edge portion; a first sealing element engaging the first face of the disk shaped portion, a radially inner portion of the first edge portion and the frame; a second sealing element engaging the second face of the disk shaped portion, a radially inner portion of the second edge portion and the frame.

2. A diaphragm assembly according to claim 1, wherein each of the first sealing element and the second sealing element comprises an O-ring.

3. A diaphragm assembly according to claim 1, wherein the diaphragm member comprises a monolithic fluoropolymer element.

4. A diaphragm assembly according to claim 1, wherein the diaphragm member comprises polytetrafluoroethylene.

5. A diaphragm assembly according to claim 1, wherein the diaphragm member comprises a monolithic element.

6. A diaphragm assembly according to claim 1, wherein the diaphragm member comprises a monolithic polytetrafluoroethylene element.

7. A diaphragm assembly according to claim 1, wherein the diaphragm member comprises a monolithic fluoropolymer element.

8. A diaphragm pump comprising: a housing having a pumping chamber containing fluid to be pumped; a cylinder; a piston sliding in a reciprocating motion in the cylinder; a diaphragm assembly coupled to the piston comprising: a diaphragm member in fluid communication with the pumping chamber, the diaphragm member comprising: a disk shaped portion having a first face and an opposed second face; a first edge portion extending substantially transverse to the first face of the disk shaped portion; a second edge portion extending substantially transverse to the second face of the disk shaped portion; a first sealing element engaging the first face of the disk shaped portion and a radially inner portion of the first edge portion; a second sealing element engaging the second face of the disk shaped portion and a radially inner portion of the second edge portion; the housing being configured to support and seal a periphery of the diaphragm member, the housing having first and second clamping faces engaging the first and second faces of the diaphragm member and defining a cavity configured to receive the first edge portion and the first sealing element and the second edge portion and the second sealing element.

9. A diaphragm pump according to claim 8, wherein the diaphragm member comprises polytetrafluoroethylene.

10. A diaphragm pump according to claim 8, wherein the diaphragm member comprises a monolithic element.

11. A diaphragm pump according to claim 8, wherein the diaphragm member comprises a monolithic polytetrafluoroethylene element.

12. A diaphragm pump according to claim 8, wherein each of the first sealing element and the second sealing element comprises an O-ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Referring now to the drawings, wherein like reference numerals and letters indicate corresponding structure throughout the several views:

(2) FIG. 1 is a side sectional view of a diaphragm pump according to the principles of the present invention;

(3) FIG. 2 is a front perspective view of a diaphragm for the diaphragm pump shown in FIG. 1;

(4) FIG. 3 is a rear perspective view of the diaphragm shown in FIG. 2;

(5) FIG. 4 is a front elevational view of a diaphragm for the diaphragm shown in FIG. 2;

(6) FIG. 5 is a side section view of the diaphragm taken along line 5-5 of FIG. 4;

(7) FIG. 6 is a detail sectional view of the piston mounting portion of the diaphragm shown in FIG. 5;

(8) FIG. 7 is a detail view of an edge of the diaphragm shown in FIG. 5;

(9) FIG. 8 is a sectional view of the edge of the diaphragm mounted in the diaphragm pump; and

(10) FIG. 9 is a sectional view of the edge of an alternate embodiment of the diaphragm mounted in the diaphragm pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(11) Referring now to the drawings and in particular to FIG. 1, there is shown a diaphragm pump, generally designated (10).

(12) The pump (10) includes a housing (12) also functioning as a crankcase, a piston housing (14), and a manifold (16). The piston housing (14) defines a transfer or hydraulic chamber (20), and a plunger chamber (22). The manifold (16) defines a pumping chamber (24) and includes inlet valves (80) and outlet valves (82).

(13) A crankshaft (26), a connecting rod (28), and a slider (30) are positioned within the crankcase (12). The slider (30) is coupled to a plunger (32) positioned within the plunger chamber (22). The transfer and plunger chambers (20), (22) are in fluid communication with each other such that fluid drawn into or forced out of the plunger chamber (22) draws the diaphragm (18) into a retracted position or forces the diaphragm into an extended position to achieve a pumping action.

(14) A diaphragm rod (34) extends from the diaphragm (18) through the transfer chamber (20). A spring (36) is positioned co-axially with the rod (34) to exert a biasing force on the diaphragm (18) in a rearward direction to help maintain a higher pressure condition in the transfer chamber (20) than in the pumping chamber (24).

(15) Referring to FIGS. 2-7, in a first embodiment, the diaphragm (18) is a monolithic element and includes a disk-shaped center planar portion (40) and a first lip (42) and a second lip (44) on the outermost edge of the disk shaped portion (40) and extending transversely to the planar disk portion (40). The first lip (42) is on the hydraulic chamber side of the diaphragm (18) and the second lip (44) is on the pumping chamber side of the diaphragm (18). A mounting portion (38) extends outward from the center of the face of the planar portion (40) on the hydraulic chamber side of the diaphragm (18). For metering pump applications pumping harsh fluids, the diaphragm (18) is typically made from a fluoropolymer and in particular may be made from polytetrafluoroethylene (PTFE), commonly marketed as TEFLON, or may be made from GYLON. The material used depends on whether the fluid being pumped is harsh and requires special materials that will not degrade if contacted by the fluid.

(16) As shown in FIG. 8, adjacent to the lips are two associated O-rings. A first O-ring (46) on the hydraulic chamber side is preferably made of an elastomer compatible with the hydraulic fluid. A second O-ring (48) is on the pumping chamber side and is exposed to the same fluid as the fluid side of the diaphragm (18). For harsh fluid uses, the second O-ring (48) is therefore typically made from PTFE, such as TEFLON, or GYLON or is PTFE coated. Two sections of the housing (14) clamp against the opposed faces of the planar portion (40). The housing (14) defines a first recess or cavity (56) configured to receive the first lip (42) and the first O-ring (46) and a second recess or cavity configured to receive the second lip (44) and the second O-ring (48). The first cavity (56) includes a groove wall (50) engaged by the first lip (42) and the second cavity (58) includes a groove wall (52) engaged by the second lip (44).

(17) Referring now to FIG. 9, in a second embodiment, a double diaphragm arrangement (60) is used in diaphragm pumps for leak detection. In this embodiment, the pump (10) uses a first diaphragm (62) and a second diaphragm (64) attached to and separated by a porous mesh material (66). The first diaphragm (62) faces the hydraulic chamber (20) and has a single lip (70) that seals against the groove wall (50). The second diaphragm (64) is on the pumping chamber side and has a single lip (72) that seals against the groove wall (52). The double diaphragm arrangement also includes the first O-ring (46) and the second O-ring (48) as with diaphragm (10). The diaphragms (62), (64) may be made of the same or different materials. However, the diaphragm (64) may need to be made of PTFE as the diaphragm (64) may come into contact with harsh fluids being pumped.

(18) In operation, on each pressure stroke of the pump (10), pressure increases in both the hydraulic chamber (20) and the pumping chamber (24). Increasing pressure forces the O-rings (46) and (48) outward to push on the lips (42) and (44) respectively. As force is applied to the sealing lips (42) and (44), the lips (42) and (44) are forced against the respective first groove wall (50) and the second groove wall 52. This deformation will occur even if there is some leakage past an O-ring (46) or (48). When the first and second lips (42) and (44) are forced against the groove walls (50) and (52) high contact pressure is generated that resists leakage past the contacting surfaces to the atmospheric leak path (54). As the pressure in the pumping and hydraulic chambers (24, 20) increases, the contact pressure of each of the lips (42) and (44) against the respective walls (50) and (52) also increases. This creates a self-energizing seal. In addition, by the lips (42) and (44) being forced tightly against the respective walls (50) and 52, any gap that an O-ring could extrude through is closed, having the same effect as an anti-extrusion backup ring.

(19) It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.