Diaphragm pump and fluid cover

Abstract: A diaphragm pump housing (12) is designed for molding out of plastics and utilizes a ribbing design which allows a high degree of strength while using a minimal amount of material and/or material having lesser strength. The rib design has an outer circumferential rib (22) about the periphery of the pump housing and a plurality of radially extending ribs (28) which extend outwardly from the center of the housing to the outer circumferential rib (22). Fastener apertures (30) are used to tie together the parts of the pump and the fastener apertures (30) are located between the radially extending ribs (28) in the outer circumferential rib (22). An intermediate circumferential rib (24) is provided adjacent the outer circumferential rib (22). The height of the ribs increases from the center of the housing outwardly to the outer circumference. The radially extending and the circumferential ribs (28,22,24,26) are the same height at locations where they intersect. This high strength design also allows the use of one piece inlet and outlet manifolds without undue flexing or leakage.

Description: The present invention relates to fluid covers for diaphragm pumps. In particular, it relates to ribbing designs of the fluid covers. Air operated double diaphragm pumps have been known and used for many years for a variety of applications. In recent years plastic molded versions of such pumps have become increasingly popular due to the increased chemical compatibility offered by the various plastic materials available. Such plastic pumps have been mainly popular in the smaller sizes as larger size plastic pumps typically have been required to be manufactured out of a metal in order to achieve sufficient strength for those larger sizes. While various rib designs have been utilized to increase the strength of the fluid housings, such housings still tend to have relatively low burst strengths or require the use of stronger filled materials in order to achieve sufficient strength. EP-A-0308541 discloses a diaphragm pump with a strengthened pressure chamber. DE-A-2255414 describes a check valve for a diaphragm pump. It is an object of this invention to provide a design capable of being molded out of a plastics material which achieves sufficient strength to provide safe operation at high pressures and which can be easily and inexpensively molded from readily available and inexpensive materials. It is another object of this invention to provide high strength at both ambient and high temperatures and to reduce possible leakage paths. By designing a strong fluid cover, one-piece inlet and outlet manifolds may be utilized. According to one aspect of the present invention, there is provided a diaphragm pump fluid cover comprising: an outer circumferential rib; a plurality of radially extending ribs; and a plurality of hollow cylindrical fastener bosses spaced around the perimeter of said cover and each having an inner circumference and an outer circumference, the inner circumference of each fastener boss defining a respective fastener aperture, characterised in that: the outer circumference of each fastener boss spans the separation between two adjacent radial ribs so as to be contiguous therewith. The provision of the outer circumferential rib strengthens the perimeter of the cover. Further, when the fastening apertures are wholly, or partly, situated in the outer circumferential rib, the rib acts to compensate for any weakness due to the openings. The provision of the radially extending ribs strengthens the cover across its surface. The provision of the circumferential rib and the radially extending ribs, both independently and in combination, results in an improved strengthening of the cover in the area which surrounds the fluid inlet and outlet. Thus a one-piece inlet and outlet manifold may be used in a diaphragm pump having such a cover. A cover according to the present invention comprising, for example, an outer circumferential rib and a plurality of radially extending ribs, may require a reduced number of fasteners. Accordingly, the costs involved in producing such a cover as well as the production time are reduced. The cover may have one or more further circumferential ribs. Preferably it has a further circumferential rib close to or contiguous with the centre of the cover and/or a further circumferential rib close to the outer circumferential rib. Optionally, in a cover having an outer circumferential rib and one or more further circumferential ribs, the height of the ribs increases from the centre of the housing outwardly to the outer circumference. The radially extending and circumferential ribs are substantially the same height where they intersect. According to yet another aspect of the present invention, there is provided a diaphragm pump having one or more fluid covers according to the present invention. In one embodiment of the present invention, the diaphragm pump fluid cover has a domed fluid chamber surface and comprises a generally uniform thickness, an outer circumferential rib, a plurality of radially extending ribs, and a plurality of fastener apertures located in said outer circumferential rib and intermediate said radially extending ribs, the number of said radially extending ribs being greater than the number of said fastener apertures. In a preferred embodiment, the fluid cover is designed for molding from a material such as polypropylene. A plurality of ribs extend upwardly from the outer surface of the dome of the cover and there are generally three circumferential ribs and a plurality of radially extending ribs which form a ribbing system which provides an improvement of the instant invention. In particular, an outer circumferential rib extends above the periphery of the device. A plurality of radially extending ribs extend outwardly from the center of the fluid cover and intersect the outer circumferential ribs. A plurality of fastener openings are provided in the cover to allow it to be bolted or otherwise fastened to the center section of the pump. The fastener apertures are located in the outer circumferential rib and between the radially extending ribs. There are fewer fasteners than radial ribs as the design does not require a large number of fasteners. An intermediate circumferential rib is located closely adjacent the outer circumferential rib while an inner circumferential rib is located adjacent the center of the dome. A one-piece manifold is utilized which greatly decreases the number of fluid paths which could possibly leak. These and other objects and advantages of the invention will appear more fully from the following description made in conjunction with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views. Embodiments of the present invention will now be described with reference to the accompanying drawings, of which: Figure 1 is a perspective view of the pump utilizing the fluid cover according to an embodiment of the present invention; Figure 2 is a view showing the main outer surface of the fluid cover; Figure 3 is a side view of the fluid cover; Figure 4 is an end view of the fluid cover; Figure 5 is a perspective view of the inner side of the fluid cover; Figure 6 is a perspective view of the fluid cover; Figure 7 is a sectional view taken along line 7-7 of Figure 2; Figure 8 is a sectional view taken along line 8-8 of Figure 2; Figure 9 is a sectional view taken along line 9-9 of Figure 2. The air-operated double diaphragm pump of an embodiment of the instant invention, generally designated (10) is best shown and seen in Figure 1 and is comprised generally of two fluid housings (12) which have attached thereto an inlet manifold (14) and an outlet manifold (16). Air housings (18) are attached to each fluid housing and are also molded of one piece. A diaphragm (not shown) is sandwiched between each air housing (18) and fluid housing (12). An air valve section (not shown) is located between the air housings (18). Turning more specifically to the fluid housing (12) of the instant invention, the dome (20) is best seen in Figure 9 and has a thickness of approximately 0.4 inches (10.2mm). The diameter of the fluid chamber in the dome is approximately 5.88 inches (14.9cm). Dome (20) is comprised of inner surface (20a) and outer surface (20b). Dome (20) also has a sealing surface (20c) having an annular recess (20d) for receiving and retaining the diaphragm edge. Sealing surface (20c) is located on flange (20e) which has extending upwardly therefrom an outer circumferential rib (22). Located slightly inwardly of outer circumferential rib (22) is intermediate circumferential rib (24). An inner circumferential rib (26) is located adjacent the center of dome (20). Outer circumferential rib (22) extends upwardly from flange (20e) approximately 0.8 inch (20.3mm). The intermediate circumferential rib (24) extends upwardly from outer surface (20b) approximately 1.07 inches (27.2mm) on its outer side and approximately 0.72 inches (18.3mm) on its inner side. Inner circumferential rib (26) extends upwardly approximately 0.46 inches (11.7mm) on its outer side and approximately 0.23 inches (5.84mm) on its inner side. As can be seen more specifically in Figure 9, radially extending ribs (28) follow the contour formed from the top of the respective ribs (22, 24 and 26) to form a smooth transition between. A plurality of fastener holes (30) are located on the outer circumferential rib (22) and are used to fasten pump (10) together by insertion of bolts or other conventional fastening mechanisms. A center boss (32) serves to terminate radially extending ribs (28). Inlet (34) and outlet (36) flanges are molded into cover (12) and serve as the termination of inlet passage (38) and outlet passage (40) respectively. The dimensions and figures referred to as being the preferred embodiment are designed for use in a 1 inch (25.4mm) pump that is molded of polypropylene and provides a burst strength of approximately 3.45x10 6 Nm -2 (500 psi). This design is of course suited for use in pumps of other sizes as well. It is contemplated that various changes and modifications may be made to the pump without departing from the scope of the invention as defined by the following claims.

Claims: A diaphragm pump fluid cover (12) comprising: an outer circumferential rib (22); a plurality of radially extending ribs (28); and a plurality of hollow cylindrical fastener bosses spaced around the perimeter of said cover and each having an inner circumference and an outer circumference, the inner circumference of each fastener boss defining a respective fastener aperture, characterised in that: the outer circumference of each fastener boss spans the separation between two adjacent radial ribs so as to be contiguous therewith. A diaphragm pump fluid cover as claimed in claim 1, wherein said outer circumferential rib is spaced radially inwards from an outermost periphery of said cover. A diaphragm pump fluid cover as claimed in claim 1 or claim 2, further comprising an intermediate circumferential rib (24) spaced radially inwards from said outer circumferential rib and a radial strut extending substantially from said intermediate circumferential rib to a fastener outer circumference. A diaphragm pump fluid cover as claimed in claim 3, wherein said intermediate circumferential rib is near said outer circumferential rib. A diaphragm pump fluid cover as claimed in any one of the preceding claims, further comprising an inlet (38) passage, an outlet (40) passage and further hollow cylindrical fastener bosses adjacent the passages each having an inner circumference and an outer circumference, the inner circumference of each further fastener boss defining a respective fastener aperture, with the outer circumference of each further fastener boss being contiguous with only a single radial rib. A diaphragm pump fluid cover as claimed in any one of the preceding claims having a domed chamber surface (20). A diaphragm pump fluid cover as claimed in any one of the preceding claims, further comprising an inner circumferential rib (26) adjacent the centre of said cover. A diaphragm pump fluid cover as claimed in claim 7, wherein a height of said outer circumferential rib is greater than that of said inner circumferential rib. A diaphragm pump fluid cover as claimed in claim 7 or claim 8, wherein the radially extending ribs taper from the outer circumferential rib to the inner circumferential rib. A diaphragm pump fluid cover as claimed in any one of claims 4 to 9, further comprising inlet (34) and outlet (36) flanges terminating said inlet and outlet passages. A diaphragm pump (10) comprising at least one fluid cover (12) as claimed in any one of the preceding claims. A diaphragm pump as claimed in claim 11 comprising: two fluid covers (12); a centre section comprising air chambers and an air valve; a one piece intake manifold (14) attached to the fluid covers (12); and a one piece outlet manifold (16) attached to the fluid covers (12).

Inventors: JOHNSON HAROLD D, KVINGE DAVID J, JOHNSON, HAROLD D., KVINGE, DAVID J.
Applicants: GRACO INC, GRACO INC.
Application year: 1995
Main classification: F04B43
IPC codes: F04B43, F04B53