Diaphragm Pump and Valve Assembly for a Diaphragm Pump

The present patent application relates to a diaphragm pump that addresses various problems associated with conventional pumps.

Diaphragm pumps are widely used for variety of applications in many industries, and provide reliable and precise fluid delivery. Although diaphragm pumps generally perform in a satisfactory manner, existing designs suffer from certain limitations, which can impede their overall performance and reliability.

Conventional diaphragm pumps use valves, orifices and related components with round cross-sections. While such configurations generally perform adequately, the layout of such components does not maximize available space and other geometries may achieve greater flows and capacities for similarly sized pumps. Volumetric efficiencies may be increased if components have geometries that require less spacing between pumping chambers and flow passages and/or larger chambers and flow passages or greater numbers of pumping chambers and associated flow passages are utilized.

Moreover, valve designs may be adopted that allow use with planar seating surfaces to reduce the complexity and cost used for machined valve seats having rounded surface. Preloading of valve elements ensures more reliable sealing and prevents inconsistent performance, leaking and minimizes residual fluid during flushing. With preloaded valves, repeatability is achieved for consistent pumping performance.

Another issue for components in pumps is the tendency for some elements to rotate, increasing wear during use. Such spinning may accelerate wear of engagement surfaces and lead to leakage and or failure of some components. For some elements, a non-round cross-section may prevent spinning and associated wear. Moreover, although some elements such as diaphragms are mount with a threaded connection, they may unscrew. It is appreciated that a threaded connection, along with clamped edges, would prevent rotation and related problems.

The diaphragm pump of the present invention addresses these problems and others associated with conventional pump designs. By reducing volumes, minimizing residual fluid, simplifying valve sealing surfaces, preloading the valve design, maximizing flow area, and eliminating unexpected disassembly of threaded interfaces, the invention significantly improves pump performance, reliability, and ease of manufacturing.

The present invention is directed to a diaphragm pump with flexible valves mounting to a planar valve plate. The pump includes a head and a motor. The head includes a lower housing assembly and an upper housing assembly. A valve plate assembly is mounted intermediate the upper housing assembly and the lower housing assembly.

A drive shaft extends from the motor, drives the components in the head, and actuates the diaphragm and valves. The drive shaft is retained within a bearing or bearings and drives a wobble plate shaft. The wobble plate shaft includes a cam surface, which is skewed relative to a longitudinal axis of the shaft and therefore imparts a “wobble” as the wobble plate shaft rotates to convert axial motion into motion so that the face of the wobble plate oscillates. The oscillating motion of the wobble plate stretches and deforms a plurality of distinct diaphragms to create a pumping action. The pump may typically include five equally spaced diaphragm chambers and includes an inlet valve and an outlet valve associated with each diaphragm. However, other numbers of diaphragms and associated valves are also possible. As the skewed wobble plate oscillates back and forth, the diaphragms are deformed back and forth to pump fluid. The valves fit into the valve plate assembly that spaces the valves.

In one embodiment, the pump head generally includes the wobble plate and five annularly spaced diaphragm engagement members. The engagement members are aligned with and extend through orifices in a diaphragm plate. The diaphragm plate receives the five diaphragms and abuts a valve plate. The valve plate includes an inlet valve mounting surface on one face and an outlet valve mounting surface on an opposite face. The inlet valve mounting surface has five valve seats aligning with the diaphragms. An inlet valve element mounts in an associated valve seat while an outlet valve element extends from the opposite side and mounts with an opposite orientation to the associated inlet valve element. The valve plate makes a sealed engagement with gaskets to an end housing of the head. The end housing defines fluid channels to fluidly connect the fluid inlet port to the valves and the diaphragms. The fluid ports may include thread connectors, bayonet type connectors, or other quick connects/disconnects and may also have adapters for coupling to different types and sizes of fittings for different applications.

The diaphragm engagement members extend as cylinders spaced about a periphery of the wobble plate. Each diaphragm includes a deformable portion that engages pumped fluid and is extended and retracted due to the motion of the wobble plate. Each diaphragm also includes an outer lip to seal against the diaphragm plate and forms a pumping chamber. An internal support body supports the deformable portion. The internal support body bonds to the deformable portion as well as forming a mechanical coupling. A threaded male connector extends from the back of the diaphragm from the internal support body and is configured to mate with a threaded hole of a corresponding diaphragm engagement member. In addition, the edges of the diaphragms are clamped so that the diaphragms do not unthread.

In operation, pumped fluid flows from the inlet port through fluid passages to the inlet valves. When an associate diaphragm is in a retracted position, in operation an aligned inlet valve would open and draw fluid through the inlet valve. When the diaphragm is pushed by oscillation of the wobble plate, the diaphragm expands outward. In operation this closes the inlet valve while the associated outlet valve opens. The pumped fluid generally flows through an inlet port through the head and exits through an outlet port. The pumped fluid is initially drawn from the inlet port into the pumping chambers through the valve plate assembly by the diaphragm. The pumped fluid then passes through an opening in the center of the valve plate and through the outlet cavity to the outlet port.

The valve plate has recessed valve seats that form pumping chambers with associated diaphragms. Unlike conventional valve seats with a rounded or curved surface, each of the valve seats has a planar surface for engagement with associated inlet valve elements and outlet valve elements. As explained hereinafter, the valves are configured with an arcing engagement surface that is easily molded and provides a biasing force to maintain engagement with the valve seat. Therefore, more difficult machining of a valve plate is avoided due to simpler geometry.

The valve plate includes inlet valve mounting holes and outlet valve mounting holes for receiving inlet valve elements and outlet valve elements, respectively. In some embodiments, the holes have an oval cross-section to receive the complementary oval stem portions of valve elements, but non-circular cross-sections are also foreseen. To facilitate acceptance of the valve elements and to avoid sharp edges that may tear the elastic valve elements, the corners proximate the ends of the inlet valve mounting holes and the outlet valve holes are radiused corners, to decrease stress on the valve elements. The valve plate also has inlet fluid passages extending through the thickness of the valve plate disposed around the inlet valve mounting holes, and outlet fluid passages extending through the thickness of the valve plate disposed radially outward in an arc around the outlet valve mounting holes. It can be appreciated that although the valve plate as shown has ten inlet fluid passages for each inlet valve and six outlet fluid passages for each outlet valve, different numbers and/or diameters and/or arrangements are envisioned depending upon the application and requirements for a particular pump. However, the fluid passages must be positioned so that they may be covered by a flap of a corresponding valve element to ensure proper operation.

It is appreciated that the shape and arrangement of the valve seats, the valve elements, the valve mounting holes, and the fluid passages achieves improved performance and efficiencies as compared to similarly sized conventional pumps. Increases in flow passage area of 30% or more have been achieved over similar sized pumps that have valve components with conventional round geometries.

Each of the valve elements is configured initially to ease insertion and mounting to the valve plate. The valve elements each include a transverse flap with a stem extending from a first face of the flap and defining a longitudinal axis. The flap is flexible and configured to deflect to open and close. A first portion of the stem extends to an intermediate portion, which has a greater transverse width and depth than the stem portion. An end portion extends from the intermediate portion and is narrower in both depth and width than the first stem portion and the intermediate stem portion. It is appreciated that the width of all portions, have a greater first transverse dimension (width) than a second transverse dimension (depth). The peripheries of the portions may be oval or elliptical, as shown and other non-circular cross-sections. For other applications, a semi-circular cross-section or crescent-shaped cross-section may be used. It is also possible to use a flap having a different cross-sectional shape than the stem to adapt to different arrangement of flow passages. The non-circular cross-sections achieve more efficient layout and also prevent valve elements from spinning. The valve elements may be used as either inlet valves or outlet valves and are interchangeable. The valve elements are made of a molded elastic material. Examples of suitable materials include ethylene propylene diene monomer (EPDM), Fluorine Kautschuk Material (FKM), or materials containing butadiene and sodium, such as BUNA®. It is also appreciated that the face of the flap facing the stem has an angled surface that forms a slightly angled surface that may be convex with an edge of the flap longitudinally closer to the end of the stem to improvement engagement with planar mounting surfaces of the valve plate.

The valve elements mount to the valve plate by being pulled by the end portion through a corresponding oval hole. The holes have a larger cross section than the end portion of the stem to facilitate insertion, so that the end portion may be more easily gripped for pulling through the hole. The length of the first portion of the stem as molded is less than the length of a corresponding hole through the valve plate. Therefore, the valve element must be stretched so that the widened intermediate portion is pulled through the hole and then engages a valve mounting surface. Once a valve element is fully inserted, the end portion is trimmed from the valve element. In addition, the first portion is stretched and lengthened compared to an initial molded configuration. It can be appreciated that with this mounting arrangement, each of the valve elements is preloaded and pressed against both faces of the valve plate.

These features of novelty and various other advantages that characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings that form a further part hereof, and to the accompanying descriptive matter, in which there is illustrated and described a preferred embodiment of the invention.

Referring now to the drawings and in particular to, there is shown a diaphragm pump, generally designated (). The pump () includes a head assembly () in a housing assembly () and a motor assembly () in a housing assembly (). The pump () mounts with a bracket () to other structure and may include electrical and/or control components ().

Referring now to, extending from the motor () is a motor shaft () that couples to and drives a wobble plate shaft () through a coupling (). A wobble plate () actuates diaphragms (). The wobble plate shaft () includes a cam surface (), which is skewed relative to a longitudinal axis of the shaft () and therefore imparts a “wobble” as the wobble plate shaft () rotates to convert axial motion into oscillation of the wobble plate (). In the embodiment shown the pump () includes five diaphragms, such as shown in. The face of the wobble plate () moves in slightly arcing motion that stretches and deforms each of the spaced diaphragms () in turn. In the embodiment shown, the pump () includes five chambers and five sets of diaphragms (), associated inlet valves (A) and outlet valves (B). However, other numbers of diaphragms and associated valves are also possible. As the wobble plate () rotates and oscillates back and forth or “wobbles”, the diaphragms () are actuated and the fluid is pumped through the head () from a fluid outlet () to a fluid discharge port ().

Referring now to, the head () generally includes the wobble plate () and five annularly space diaphragm engagement members (). The engagement members () are aligned with and extend through orifices () in a diaphragm plate (). The diaphragm plate () receives the five diaphragms () and abuts a valve plate (). The valve plate () includes an inlet valve mounting surface () on one face and an outlet valve mounting surface () on an opposite face. The inlet valve mounting surface () has five valve seats () aligning with the diaphragms (). An inlet valve element (A) mounts in an associated valve seat () while an outlet valve element (B) extends from the opposite side () and mounts with an opposite orientation to the associated inlet valve element (A). The valve plate makes a sealed engagement with gaskets () to an end housing () of the head (). The end housing () defines fluid channels to fluidly connect the fluid inlet port () to the valves (A) and (B) and the diaphragms (). The fluid ports () and () may include thread connectors, bayonet type connectors, or other quick connects/disconnects and may also have adapters for coupling to various types and sizes of fittings for different applications.

Referring now to, the operation of the diaphragms () and valves (A) and (B) can be understood. The pumped fluid flows from the inlet port () through fluid passages () to the inlet valves (A). When an associate diaphragm is in a mid-stroke position, as shown in, in operation an aligned inlet valve (A) would open and draw fluid through the inlet valve (A). When the diaphragm is pushed by movement of the wobble plate (), the diaphragm () expands outward as shown in. In operation this closes the inlet valve (A) while the associated outlet valve (B) opens. Fluid then flows through fluid passages () and to the outlet port (). The pumped fluid generally flows through an inlet port (A) through the head () and exits through an outlet port (B). The pumped fluid is initially drawn from the inlet port (A) into the pumping chambers (A), (B) and (C) through the valve plate assembly () by the diaphragm (). The pumped fluid then passes through an opening in the center of the valve plate () and through the outlet cavity () to the outlet port (B).

Referring to, the valve plate () of the present invention is shown. The valve plate () has recessed valve seats () formed in the inlet valve mounting surface (). Unlike conventional valve seats with a rounded or curved surface, each of the valve seats () has a planar surface for engagement with flaps of associated inlet valve elements (A). Flaps of the outlet valve elements (B) engage the outlet valve surface (). As explained hereinafter, the valves () are configured with an arcing engagement surface that is easily molded and provides a biasing force to maintain engagement with the valve seat (). The configuration of the valve elements () with improved sealing helps to minimize residual fluid during flushing. Therefore, more difficult machining of a valve plate is avoided due to simpler geometry.

As shown in, the valve plate () includes inlet valve mounting holes () and outlet valve mounting holes () for receiving inlet valve elements (A) and outlet valve elements (B) respectively. The holes () and () have a non-circular cross-section, such as an oval cross-section to receive the complementary non-circular stem portions, such as oval cross-sections, of valve elements (). To facilitate acceptance of the valve elements () and to avoid sharp edges that may tear the elastic valve elements (), the corners proximate the ends of the inlet valve mounting holes () and the outlet valve holes () are radiused corners (), shown most clearly in, to decrease stress on the valve elements (). The valve plate () also has inlet fluid passages () extending through the thickness of the valve plate () disposed around the inlet valve mounting holes (), and outlet fluid passages () extending through the thickness of the valve plate () disposed radially outward in an arc around the outlet valve mounting holes (). The fluid passages () and () have radiused edges on the end of the passage covered by the flap (). Such rounded edges decrease stress and wear of the valve flap (). It is also appreciated that such radiused edges are easier to machine relative to conventional pumps due to the planar surfaces in the valve seats () and the outlet valve mounting surface (). It can be appreciated that although the valve plate () as shown has ten inlet fluid passages () for each inlet valve and six outlet fluid passages () for each outlet valve, different numbers and/or diameters and/or arrangements are envisioned depending upon the application and requirements for a particular pump. However, the fluid passages () and () must be positioned so that they may be covered by a flap of a corresponding valve element ().

It is appreciated that the shape and arrangement of the valve seats (), the valve elements (A) and (B), the valve mounting holes () and (), and the fluid passages () and (), achieves improved performance and efficiencies as compared to similarly sized conventional pumps due to greater flow area.

Referring to, each of the valve elements () is configured initially to ease insertion and mounting to the valve plate. The valve elements () each include a flap () with a stem extending from a first face (A) of the flap () and defining a longitudinal axis. The flap () is flexible and configured to deflect to open and close. A first portion of the stem () extends to an intermediate portion () that has a greater transverse width and depth than the stem portion. An end portion () extends from the intermediate portion and is narrower in both depth and width than the first stem portion and the intermediate stem portion (). It is appreciated that the width of all portions (), () and () have a greater first transverse dimension (width) than a second transverse dimension (depth). The peripheries of the portions (), (), () may be elliptical or oval, for example. The valve elements () may be used as either inlet valves (A) or outlet valves (B) and are interchangeable. The valve elements () are made of a durable molded elastic material. Examples of suitable materials include ethylene propylene diene monomer (EPDM), Fluorine Kautschuk Material (FKM), or materials containing butadiene and sodium, such as BUNA®. It is also appreciated that the face (A) of the flap facing the stem () has an angled surface that forms a slightly angled surface that may be convex with an edge of the flap () longitudinally closer to the end () of the stem to improvement engagement with planar mounting surfaces of the valve plate.

The valve elements () mount to the valve plate by being pulled by the end portion () through a corresponding oval hole () or (). The holes () and () have a larger cross section than the end portion of the stem () to facilitate insertion, so that the end portion () may be gripped for pulling through the hole () or (). The length of the first portion () of the stem as molded is less than the length of a corresponding hole () or () through the valve plate. Therefore, the valve clement () must be stretched so that the widened intermediate portion () is pulled through the hole () or () and then engages a valve mounting surface () or (). Once a valve element () is fully inserted, the end portion () is trimmed and the valve element () is configured as shown in. It is appreciated, that the stem end in the widened portion () acts as a plug and maintains the valve clement () in an associated hole () or (). In addition, the first portion () is stretched and lengthened compared to an initial molded configuration. It can be appreciated that with this mounting arrangement, each of the valve elements () is preloaded and pressed against both faces of the valve plate (). The improved sealing at edges of the flap () of such an arrangement prevents residual fluid from being trapped around the stem ().

Referring to, the diaphragms () and engagement with the wobble plate () are shown. The engagement members () extend as cylinders spaced about a periphery of the wobble plate (). Referring to, each diaphragm includes a deformable portion () that engages pumped fluid and is extended and retracted due to the motion of the wobble plate (). Each diaphragm () also includes an outer lip () to seal against the diaphragm plate, as shown, for example, in. An internal support body () supports the deformable portion, as also shown in. The internal support body () bonds to the deformable portion () as well as forming a mechanical coupling. A threaded male connector () extends from the back of the diaphragm () from the internal support body () and is configured to mate with a complementary female threaded hole of a corresponding diaphragm engagement member (), such as shown in. Beads at the edges () of the diaphragms () are clamped so that the diaphragms () do not unscrew.

With the geometries achieved by the present invention, increases over conventional pumps having a comparable size due to changing the conventional round/circular passage layout to an elliptical passage and increases in flow passage size may be achieved. Conventional pumps having a comparable size may have four or five chambers. It is appreciated that five chambers, diaphragms, and sets of valves requires less flow through each valve than four. However, further changing the geometries of components from round to oval/elliptical increased the flow area by approximately an additional% at the inlet and outlets of each chamber by adding more through holes/passages than is possible with components and arrangements of a conventional five chamber pump of comparable size having rounds geometries. Moreover, increases of more than 60% may be achieved over the conventional four chamber pump of comparable size with round components. Moreover, by improving the ratio flow/area of the passages for the same flow, volumetric efficiency improves and fluid shear is reduced. It is appreciated that pumping capacity and performance achieves surprising increases over a pump of comparable size.

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.