DEVICE FOR PROTECTING A DIAPHRAGM PUMP FROM PRESSURE DIFFERENTIAL

Abstract

A diaphragm pump includes a transfer chamber containing hydraulic fluid and a pumping chamber for fluid to be pumped. A connecting assembly includes a plunger extending to the transfer chamber. A diaphragm connects to the connecting assembly and separates the transfer chamber and the pumping chamber. A pressure protection device mounts to the connecting assembly and is configured to seal against the transfer chamber when pressure differential, including reverse pressure differential, across the diaphragm exceeds a predetermined value. The pressure protection device is intermediate the plunger and the diaphragm and supports the diaphragm when there is excess pressure differential across the diaphragm.

Claims

1. A diaphragm pump apparatus comprising: a transfer chamber containing hydraulic fluid; a pumping chamber for fluid to be pumped; a connection assembly including a plunger extending to the transfer chamber; a diaphragm connected to the connecting assembly, the diaphragm separating the transfer chamber and the pumping chamber; and a pressure protection device mounted to the connecting assembly, the pressure protection device configured to seal against the transfer chamber when pressure differential across the diaphragm exceeds a predetermined value.

2. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device is intermediate the plunger and the diaphragm.

3. A diaphragm pump apparatus according to claim 2, wherein the pressure protection device engages a wall of the transfer chamber.

4. A diaphragm pump apparatus according to claim 2, wherein the pump comprises a hydraulic housing and the ring engages the hydraulic housing when subjected to the pressure differential.

5. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device comprises a disk.

6. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device comprises a flange.

7. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device comprises a washer.

8. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device comprises a molded ring.

9. A diaphragm pump apparatus according to claim 8, wherein the molded ring comprises a lip.

10. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device mates with the transfer chamber when deformed.

11. A diaphragm pump apparatus according to claim 1, wherein the pressure protection device has a stiffness greater than a stiffness of the diaphragm.

12. A pressure protection device for a diaphragm in a diaphragm pump, the pump having a connecting assembly mounted to a diaphragm, a transfer chamber and a pumping chamber, the pressure protection device comprising: a pressure protection device mounted to the connecting assembly, the pressure protection device configured to seal against the transfer chamber when subjected to reverse differential pressure.

13. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device supports the diaphragm on a transfer chamber side of the diaphragm.

14. A pressure protection device for a diaphragm according to claim 13, wherein the pressure protection device engages a wall of the transfer chamber.

15. A pressure protection device for a diaphragm according to claim 12, the connecting assembly comprising a plunger extending to the transfer chamber; wherein the pressure protection device is intermediate the plunger and the diaphragm.

16. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device comprises a disk.

17. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device comprises a flange.

18. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device comprises a washer.

19. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device comprises a molded ring.

20. A pressure protection device for a diaphragm according to claim 19, wherein the molded ring comprises a lip.

21. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device mates with the transfer chamber when deformed.

22. A pressure protection device for a diaphragm according to claim 12, wherein the pressure protection device has stiffness greater than a stiffness of the diaphragm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Referring now to the drawings, wherein like references letters and numerals indicate corresponding structure throughout the several views:

[0013] FIG. 1 is a side sectional view of a diaphragm pump;

[0014] FIG. 2 is a side sectional view of a plunger, diaphragm, pumping chamber and manifold for the diaphragm pump shown in FIG. 1;

[0015] FIG. 3 is a side sectional view of the diaphragm shown in FIG. 2 with the diaphragm at bottom dead center with normal bias pressure;

[0016] FIG. 4 is a side sectional view of the diaphragm shown in FIG. 3 with the diaphragm in an extended position with normal bias pressure;

[0017] FIG. 5 is a side sectional view of the diaphragm shown in FIG. 3 with the diaphragm deformed from reverse differential pressure;

[0018] FIG. 6 is a side sectional view of the diaphragm shown in FIG. 2 with a pressure differential protection device according to the principles of the present invention;

[0019] FIG. 7 is an exploded perspective view of the diaphragm assembly with the pressure differential protection device shown in FIG. 6;

[0020] FIG. 8 is a sectional view of an alternate embodiment of a pressure differential protection device according to the principles of the present invention; and

[0021] FIG. 9 is a sectional view of a further alternate embodiment of a pressure differential protection device according to the principles of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0022] Referring now to the drawings and in particular to FIG. 1, there is shown a hydraulically driven diaphragm pump, generally designated (20). The diaphragm pump (20) is driven by a crankshaft (36) mounted in a crankcase (22). A manifold (26) includes an inlet passage (74) and a discharge passage (76). The manifold (26) also includes one or more inlet check valves (72) and one or more discharge check valves (70).

[0023] In the embodiment shown, the pump (20) is a diaphragm pump and includes a diaphragm assembly (100) mounted on a valve stem (44) as shown more clearly in FIG. 2. The diaphragm assembly (100) includes a flexible diaphragm element (102) and is hydraulically driven by a plunger (42) connected to a slider (40) on a crankshaft rod (38) to the crankshaft (36). The plunger (42) extends into a hydraulic fluid chamber (32) and drives hydraulic fluid against the diaphragm. An overfill check valve (48) and an underfill check valve (50) maintain proper hydraulic fluid levels.

[0024] The diaphragm (102) receives fluid in a pumping chamber (34) and the system fluid is pumped while the diaphragm (102) deflects back and forth between an extended position and a fully retracted position. The manifold (26) includes a separate inlet check valve (72) and discharge check valves (70) for each pumping chamber in multiple diaphragm pumps.

[0025] Referring now to FIGS. 3-5 the diaphragm assembly (100) has a reciprocating motion to flex the diaphragm (102) between the pumping chamber (34) and the hydraulic fluid chamber (32). During operation, the diaphragm element (102) reciprocates along a central axis between a retracted position as shown in FIG. 3, and an extended position as shown in FIG. 4. The hydraulic fluid chamber (32) is at least partially defined by a hydraulic housing (104) including an angled portion (110).

[0026] As shown in FIG. 5, it can be appreciated that with a conventional diaphragm, should an excess reverse pressure differential situation occur, the pressure from the pumped fluid forces the diaphragm element into a discontinuity between the hydraulic housing (104), in particular the angled portion (110), and the disc shaped portion (124) of the control element (120). Such a deformation into the gap stresses the diaphragm element (102) and may lead to damage and/or failure of the diaphragm element (102) as discussed above.

[0027] As shown in FIG. 7, the diaphragm assembly (100) has the diaphragm element (102) mounted to a control element (120) including the control element shaft portion (122) and the control element disc portion (124). The fastener (126) engages the disc shaped follower (128) to mount the diaphragm (102) to the control element (120). The diaphragm engages the hydraulic housing on the hydraulic chamber side of the diaphragm.

[0028] As shown in FIGS. 6 and 7, the present invention utilizes a pressure differential protection device (140) that mounts to the diaphragm assembly (100) against the control element (120) and the diaphragm (102). The control element disc portion (124) may include a groove to receive the protection device (140) if configured as a ring type element. The protection device (140) creates a diaphragm engagement surface that provides a smooth transition and continuous support surface along the angled portion (110) of the hydraulic housing (104) and the disc portion (124) of the control element (120). Therefore, even if excessive reverse differential pressures are encountered, the backup device (140) does not allow the diaphragm element (102) to deform into a gap and supports and maintains the diaphragm element in a configuration as shown in FIG. 6. Therefore, diaphragm (102) avoids folds and/or deformations that could concentrate stresses and damage the diaphragm element (102). Furthermore, it can be appreciated that the protection device (140) prevents fluid from entering the transfer chamber and crankcase should the diaphragm (102) rupture or leak.

[0029] The embodiment of the pressure differential protection device (140) shown in FIGS. 6 and 7 is a molded ring type element of a material that provides sufficient support for the diaphragm element (102). An inner mounting portion (142) seats against the control element (120). A lip or flange (144) at the periphery of the pressure differential protection device (140 prevents a void and provides smooth and continuous support surface for the diaphragm from the control element (120) to the hydraulic housing (104) even under excess reverse pressure differential. The protection device (140) may be formed of various materials, such as ultra-high-molecular-weight polyethylene, urethane, rubber and other elastomeric materials that provide proper support and maintain a seal under pressure for extended periods. The protection device (140) preferably has a higher stiffness than the diaphragm element (102) so that the protection device (140) does not flex back and forth in a reciprocating manner with the diaphragm (102).

[0030] It can be appreciated that the protection device (140) may have multiple configurations such as a disc or an annular element. Moreover, the periphery of the protection device may be round, oval or race track shaped. The surfaces of the lip or flange (144) that do not engage the diaphragm may be configured to match the general geometry of the surrounding pump elements to provide proper and continuous support for the diaphragm element (140).

[0031] Referring now to FIG. 8, there is shown an alternate embodiment of a pressure differential protection device. A pressure differential protection device, generally designated (240) is for a diaphragm (202). The pressure differential protection device (240) is generally configured with a washer like annular planar disc portion (242) and configured to provide engagement with the hydraulic housing as a continuous support surface without gaps. The pressure differential device (240) includes a support portion (244) on the back of the disc portion (242) to ensure that the planar disc portion maintains its shape and maintains a seal even when subjected to excess reverse pressure differentials. As with the other embodiments, gaps into which the diaphragm element (202) might otherwise deform are eliminated. The pressure differential protection device (240) covers irregularities in the surface of the hydraulic chamber to provide a smoother continuous support surface against the hydraulic manifold. It can also be appreciated that the protection devices (140 and 240) may have sizes and dimensions that are varied to mate with the particular configuration of the diaphragm pump and the hydraulic chamber to provide support for the diaphragm element (102).

[0032] Referring now to FIG. 9, there is shown a further alternate embodiment of a pressure differential protection device. A pressure differential protection device, generally designated (340) is configured for a diaphragm (302). The pressure differential protection device (340) includes a ring type element (342) and that is configured to provide engagement with the hydraulic housing in a continuous support surface without gaps. The ring type element (340) may be molded and mounted to a support portion (344) that provides for retaining and supporting the ring type element (342) to ensure that the pressure differential protection device (340) maintains its shape and maintains a seal even when subjected to excess reverse pressure differentials. As with the other embodiments, gaps into which the diaphragm element (302) might otherwise deform are eliminated. The pressure differential protection device (340) covers irregularities and discontinuities in the surface of the hydraulic chamber to provide a smoother continuous support surface against the hydraulic chamber.

[0033] As with the previously discussed protection devices (140, 240), it can be appreciated that the protection device (340) may be configured to have sizes and dimensions that are varied to mate with the particular configuration of the diaphragm pump and the dimensions and shape of hydraulic chamber to provide support for the diaphragm element. Moreover, the general geometry of the protection device of the present invention may be varied and configured so as to be complementary to the walls of the surrounding chamber to form continuous gap free surfaces without sharp angles or transitions between surfaces and to maintain proper sealing to protect the diaphragm and the pump against excessive reverse pressure differentials.

[0034] 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.