Diaphragm pump method and apparatus

Abstract

An improved method and apparatus in a diaphragm pump of the type including a frame and a motor connected to the frame. A connecting rod is eccentrically mounted at one end upon a drive shaft of the motor and is directly connected at the other end to a flexible pump diaphragm. A fluid housing is connected to the frame and includes a fluid entry port and a fluid exit port. The flexible pump diaphragm is intercalated between the frame and the fluid housing. The improved apparatus includes a tubular wall coaxially positioned within the interior of the housing and defining thereby an inlet chamber within the interior of the tubular wall and an outlet chamber exterior of the tubular wall and circumferentially extending about the inlet chamber. A conduit is provided to place the fluid entry port into fluid communication with the inlet chamber. A valve plate is mounted between the diaphragm and one end of the coaxial tubular wall means and defines a pumping chamber coaxially extending above the inlet and outlet chambers. The valve plate is provided with a plurality of inlet ports above the inlet chamber and a plurality of outlet ports above the outlet chamber. A first valve operably covers the inlet port for permitting fluid to flow from the inlet chamber into the pumping chamber but preventing fluid from flowing from the pumping chamber into the inlet chamber. A second valve operably covers the outlet ports for permitting fluid to flow from the pumping chamber into the outlet chamber but preventing fluid from flowing from the outlet chamber into the pumping chamber. The improved method utilizing the foregoing apparatus includes the steps of drawing fluid into the coaxial inlet chamber and pumping the fluid into the circumferential outlet chamber coaxially disposed about the inlet chamber.

Description

BACKGROUND OF THE INVENTION

This invention relates to improvements in a diaphragm pump method and apparatus. More particularly, the invention pertains to improved methods and apparatus within the pumping chamber of a diaphragm pump.

A continuing demand exists in the pump industry for relatively small, inexpensive fluid pumps of the type which may, for example, be advantageously utilized in connection with recreational vehicles. In this connection, bilge pumps for boats, water pumps for mobile trailers, etc. are generally representative of current industry requirements.

Previously known pump designs operable to be used for recreational vehicles, etc. frequently entail the use of a small electric motor which is mounted upon the frame and serves to drive an eccentrically mounted connecting rod. The connecting rod is connected to a flexible diaphragm which is intercalated between the frame and a cylindrical fluid housing. The fluid housing is divided into halves by a central diametrical wall. An inlet is fashioned into the housing on one side of the wall and an outlet is fashioned into the housing on the other side of the wall. Therefore, one of the halves comprises an inlet chamber and the other half comprises an outlet chamber.

A valve plate is mounted on top of the fluid housing and beneath the flexible diaphragm to define a pumping chamber above the inlet and outlet chambers. The valve plate carries an inlet check valve assembly above the inlet chamber and an outlet check valve assembly above the outlet chamber.

In operation the foregoing briefly described diaphragm pump structure serves to draw fluid into the inlet chamber and pump the fluid over the dimetrical wall into the outlet chamber.

In order to reduce fluid pulsations within the pumping system, hollow dome bladders are mounted at the bottom of the inlet and outlet chambers. These bladders serve to flex against closed air pockets to absorb fluid pulsations.

For a more detailed description of at least one previously known diaphragm pump of the type briefly described above, reference may be had to a Russell U.S. Pat. No. 3,606,597 issued Sept. 20, 1971.

Notwithstanding the advantageous aspects at least theoretically attributable to small fluid pumps of the foregoing design, room for significant improvement remains.

In this connection, it would be highly desirable to provide an improved diaphragm pump of increased efficiency or performance. Further, it would be desirable to provide a simplified pump design which is readily manufacturable, easily servicable and characterized by long life of the individual components. Still further, it would be highly desirable to provide an improved diaphragm pump where water hammer and pressure pulsations within the pumping chamber are effectively attenuated.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

Objects

It is therefore a general object of the invention to provide a novel diaphgram pump method and apparatus which will provide desired results of the type previously described.

It is a specific object of the invention to provide a novel diaphragm pump method and apparatus wherein the performance or efficiency of the pumping system is facilitated.

It is a related object of the invention to provide a novel diaphragm pump method and apparatus wherein the volume of fluid flow is increased without increasing the exterior size of the fluid housing.

It is a further object of the invention to provide a novel diaphragm pump method and apparatus wherein higher fluid pressures may be accommodated.

It is still a further object of the invention to provide a novel diaphragm pump method and apparatus wherein the concentricity of pumping inlet and outlet chambers is maximized with resultant better distribution of pumping forces upon a flexible diaphragm.

It is yet a further object of the invention to provide a novel diaphragm pump method and apparatus wherein water hammer pulsations within the inlet chamber are effectively attenuated.

It is another object of the invention to provide a novel diaphragm pump method and apparatus wherein pumping fluid pulsations within an outlet chamber are effectively attenuated.

It is still another object of the invention to provide a novel diaphragm pump method and apparatus which is compact and relatively simple in design, easily manufacturable and servicable.

It is yet another object of the invention to provide a novel diaphragm pump method and apparatus wherein the individual fluid chamber components including vibration attenuation means exhibit rugged long-life characteristics which minimize service requirements to the pump.

Brief Summary

A diaphragm pump method and apparatus intended to accomplish at least some of the foregoing objects includes a diaphragm pump having, a frame and a motor connected to the frame. A connecting rod is eccentrically mounted at one end upon a drive shaft of the motor and is directly connected at the other end of a flexible pump diaphragm. A fluid housing is connected to the frame and includes a fluid entry port and a fluid exit port. The flexible pump diaphragm is intercalated between the frame and the fluid housing.

The improved apparatus includes a tubular wall coaxially positioned within the interior of the housing and defining thereby an inlet chamber within the interior of the tubular wall and an outlet chamber exterior of the tubular wall and circumferentially extending about the inlet chamber. A conduit is provided to place the fluid entry port into fluid communication with the inlet chamber. A valve plate is mounted between the diaphragm and one end of the coaxial tubular wall means and defines a pumping chamber coaxially extending above the inlet and outlet chambers. The valve plate is provided with a plurality of inlet ports above the inlet chamber and a plurality of outlet ports above the outlet chamber. A first valve operably covers the inlet port for permitting fluid to flow from the inlet chamber into the pumping chamber but preventing fluid from flowing from the pumping chamber into the inlet chamber. A second valve operably covers the outlet ports for permitting fluid to flow from the pumping chamber into the outlet chamber but preventing fluid from flowing from the outlet chamber into the pumping chamber. The improved method utilizing the foregoing apparatus includes the steps of drawing fluid into the coaxial inlet chamber and pumping the fluid into the circumferential outlet chamber coaxially disposed about the inlet chamber.

THE DRAWINGS

Further objects and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings wherein:

FIG. 1 is an axonometric view of a small diaphragm fluid pump;

FIG. 2 is a plan view of a diaphragm fluid pump including a generally square fluid housing having entrance and exit fluid ports;

FIG. 3, note sheet 2, is a partial broken-away end view of the diaphragm pump disclosed in FIGS. 1 and 2 and particularly illustrates an inlet chamber coaxially mounted within a fluid housing and a circumferential outlet chamber surrounding the inlet chamber;

FIG. 4, note sheet 3, discloses a cross sectional view taken along section line 4--4 in FIG. 2 and illustrates the provision of a pressure switch tapped into the circumferentially extending outlet chamber;

FIG. 5 is a cross sectional view taken along section line 5--5 in FIG. 3 and discloses a partially broken-away plan view of a valve plate mounted within the fluid housing;

FIG. 6, note sheet 2, discloses a cross sectional view taken along section line 6--6 in FIG. 3;

FIG. 7, note sheet 1, discloses an axonometric view of a generally cylindrical elastomeric body composed of a closed cell silicone rubber foam which is operable to be positioned within the inlet chamber to attenuate water hammer pulsations within the inlet chamber; and

FIG. 8 discloses an axonometric view of an expanded cylindrical elastomeric sleeve composed of closed cell silicone rubber foam and being operable to attenuate fluid pulsations within the outlet chamber of the diaphragm pump.

DETAILED DESCRIPTION

Diaphragm Pump Context of the Invention

Before discussing the improvement aspects of the invention, a brief summary of the diaphragm pump context of the invention will be discussed.

More particularly, and with reference to FIGS. 1 and 2, there will be seen a diaphragm type pump 10 including a frame 12 which serves to support a small electric motor 14. A connecting rod 16 is eccentrically mounted at one end by a cam 18 which is mounted upon a drive shaft 20 of the motor. A generally square fluid housing 22 is connected to a top plate 24 of the frame 12 by the provision of conventional threaded fasteners 26 mounted at each of the corners of the frame. A fluid inlet port 28 is fashioned within the housing 22 on one side thereof and a fluid exit port 30 is fashioned into the housing 22 on a generally opposite side thereof. A flexible diaphragm 32, note FIG. 3, is connected to the other end of the connecting rod 16 by interior and exterior diaphragm discs 34 and 36 and a threaded fastener 40.

Improved Fluid Chamber

Referring now particularly to FIGS. 3-6, there will be seen various views of an improved fluid chamber comprising the subject matter of the instant invention.

As noted in FIG. 6, the generally square fluid chamber 12 is provided with a central longitudinally extending axis 42. A tubular cylindrical wall 44 is coaxially positioned with respect to axis 42 within the interior of the housing 22 and serves to define by the interior surface thereof a fluid inlet chamber 46.

A second cylindrical tubular wall 48 is coaxially positioned within the interior of the fluid chamber 22 and is concentrically outwardly positioned with respect to the wall 44. The annular cylinder between the exterior surface of wall 44 and the interior surface of wall 48 defines a generally cylindrical outlet chamber 50 circumferentially extending about the inlet chamber 46.

In order to provide fluid communication between the entry or inlet port 28 and the inlet chamber 46, a conduit 52 is fashioned through the wall of the housing 22, through the tubular wall 44, and opens into the inlet chamber 46.

A valve plate 54 is mounted upon the upper surface of cylindrical wall 44 and a plurality of supporting columns 56 positioned at regular intervals about the inner periphery of wall 48. The valve plate 54 is formed with an inner cup 57 including a cylindrical side wall 58 and a bottom plate 60. The cylindrical side wall 58 is coaxially disposed with respect to axis 42 and upwardly projects into abutting contact with the flexible diaphragm 32. The cylindrical wall 58 serves to pin the diaphragm against the under portion of plate 24 to define coaxially above the inlet and exit chambers a pumping chamber 62.

The bottom wall 60 of the cup 56 is fashioned with a plurality of fluid inlet ports 64 having axes which lie upon an imaginary ring coaxially disposed with respect to central axis 42. Radially outwardly from the inlet ports 64 are a plurality of outlet ports 66 which lie upon an imaginary circle concentrically outwardly disposed with respect to the imaginary circle of the inlet ports (note FIG. 5).

An aperture 68 is fashioned through the center of the valve plate 54 and is operable to receive a mounting stub 70 of an umbrella valve 72. The umbrella valve 72 is composed of an elastomeric material and serves to overlie and normally cover each of the inlet ports 64 lying within the confines of the cylindrical wall 44 which defines the inlet chamber 46. It will be appreciated that umbrella valve 72 is in essence an elastomeric check valve in that fluid is free to flow from the inlet chamber 46 to the pumping chamber 62 but upon pressurization of the pumping chamber 62 the umbrella valve 72 will flex into sealing abutment above the ports 64 and thus prevent fluid from entering the inlet chamber.

The valve plate 54 is fitted with a second valve 74 composed of an elastomeric disc or washer which is mounted between a lower portion of the valve plate 54 and the upper free end of the cylindrical wall 44 as at 76.

The elastomeric ring 74 like the umbrella valve 72 in essence serves as a check valve in that fluid confined within the pumping chamber 62 will serve to flex the valve 74 downwardly and thus permit the flow of fluid through outlet ports 66 peripherally about the inlet chamber 64. However, in the event pressure within the outlet chamber 50 is greater than pressure within the pumping chamber 62, the elastomeric valve will flex closed and prevent fluid from flowing from the outlet chamber 50 into the pumping chamber 62.

In order to limit the downward flexure of the elastomeric disc valve 74 a valve guard or disc 77 is also mounted at the free end of the cylindrical wall 44 and is normally flexed slightly downward to permit a normal flexing of elastomeric valve 74. The guard or backup disc 76 is perferably composed of a metallic material such as, for example, stainless steel, which will exhibit characteristics of long life while providing appropriate strength to prevent the elastomeric valve 74 from overflexing. In this connection, overflexing of valve 74 may produce excessive wear at the flexure point 78. Alternatively, the valve may open too wide to accommodate rapid osscillations of the pumping diaphragm 32.

In order to reduce and attenuate momentum pulsations created within the inlet chamber 46 by the rapid opening and closing of the umbrella valve 72, a cylindrical sleeve 80 composed of a volumetrically compressable material such as closed cell silicone rubber foam is positioned within the interior of the cylindrical inlet chamber 46. The sleeve 80 is cut at one end by a plane lying normal to the axis of the sleeve as at 82 and is positioned to abut against the bottom face of the valve plate 54. The other end of the sleeve 82 is cut by an inclined plane (note FIG. 3) such that the longest height of the sleeve 80 abuts against an inwardly projecting column 84 which is integrally fashioned with respect to cylindrical wall 44. Column 84 serves to maintain the volumetrically compressable sleeve 80 in a posture adjacent to the inlet ports 64 and thus facilitate attenuation of "water hammer" vibration produced by the rapid shutting of umbrella valve 72.

The shortest height of the sleeve 80 which is diametrically opposed to the landing column 84 extends above the inlet of the conduit 52 as at 86 to enable fluid to freely enter into the inlet chamber 46.

A cylindrical sleeve 88 composed of a fine mesh screen is mounted coaxially within the inlet chamber 46 and contiguously lies against the inner surface of the elastomeric sleeve 80. The screen 88 provides a dual function of removing foreign particles from the flow of fluid into the inlet chamber 46 and assisting the landing tab 84 in maintaining the elastomeric sleeve 80 in a posture adjacent to the inlet ports 64.

To minimize and attenuate fluid pumping pulsations within the outlet chamber 50 a second cylindrical sleeve 89 is positioned within the clinder 48. The sleeve 89 lies in a posture contiguous with the inner wall of the cylinder 48 and is preferably composed of a volumetrically compressable elastomer such as closed cell silicone rubber foam. The sleeve 89 is fashioned with a first aperture 90 operable to be positioned within the outlet chamber 50 in a posture adjacent to the exit port 30. Therefore, fluid within the outlet chamber may freely flow through the sleeve 89 and into the exit port.

The sleeve 89 (not FIG. 8) is evered in a location diameetrically opposed to the axis of the first port 90 and formed with channels 92 and 94. Thus, when the sleeve 89 is curved and placed within the wall 48 during assembly of the fluid housing, the cutouts 92 and 94 form a generally U-shaped recess which is suitable to extend upon either side of the inlet conduit 52 (note FIG. 6).

In order to control actuation of the motor 44 in accordance with a preferred pressure ratio within the outlet chamber 50 a commercial pressure switch 100 is tapped through the fluid housing and opens through a second aperture 102 formed within the volumetrically compressable sleeve 89. The pressure switch per se does not form a part of the invention and may be selected from commercially available devices such as, for example, the 25 PS series KLIXON Precision Pressure Switch manufactured by Texas Instruments, Inc. at Attleboro, Mass.

The pressure switch 100 is operably connected (not shown) to the motor 14 and serves to turn the motor on and off in response to a preselected range of pressures such as, for example, 15 to 27 psig.

Operation

In operation, once fluid within the outlet chamber 50 falls below the 15 psig the switch 100 will actuate the motor 14 thus driving the connecting rod 16 in an up-and-down reciprocating mode. The diaphragm 32 will accordingly reciprocate to draw fluid through conduit 52 into the inlet chamber 46. The umbrella check valve 72 opens during the upstroke of the diaphragm 32 within the pumping chamber 62. On each downstroke of the diaphragm 32 the elastomeric umbrella valve 72 will be snapped closed and the disc valves 74 will simultaneously open to permit the fluid to enter outlet chamber 50.

The foregoing process is rapidly repeated so as to provide a substantially continuous pumping operation until the pressure within the outlet chamber 50 reaches a preselected maximum such as, for example, 27 psig, at which time the pressure switch 100 will turn the motor 14 off.

SUMMARY OF THE MAJOR ADVANTAGES

In illustrating and describing the foregoing improvements in a diaphragm pump several novel and advantageous aspects of the invention have been specifically and inherently disclosed.

A primary advantage provided by the concentric inlet and outlet chambers is the provision of a greater valving area within substantially the same exterior fluid chamber configuration whereby geater flow rates or efficiency may be achieved without substantially increasing power requirements.

Further significant advantages are realized by the provision of volumetrically compressable cylindrical sleeves within the inlet and outlet chambers which serve to attenuate fluid pulsations within the chambers while minimizing the possibility of incidental cracks and the like resulting in failure of the vibration attenuation system. Another advantage is realized by the cylindrical nature of the outlet or high pressure chamber which permits a build-up of higher fluid pressures without unduly stressing the fluid chamber housing members.

Still further, it will be appreciated that the subject improved fluid chamber in a diaphragm pump is compact and simple in design which facilitates manufacturing ease and is readily servicable in the event of failures. In this connection, the vibration attenuation sleeves, while being extremely long-lifed, may be readily removed and replaced. Further, the metallic backup ring prevents overstressing of the second, elastomeric check valve.

Although the invention is disclosed with reference to a preferred embodiment it will be appreciated by those skilled in the art that additions, deletions, modifications, substitutions and other changes not specifically described and illustrated may be made which will fall within the purview of the appended claims.

Claims

What is claimed is:

1. In a diaphragm pump including,

a frame means;

a motor connected to said frame means;

a connecting rod eccentrically mounted at one end thereof to a drive shaft of said motor;

fluid housing means mounted upon said frame means, including

a fluid entry port, and

a fluid exit port; and

flexible pump diaphragm means affixed to said connecting rod at the other end thereof and intercalated between said frame means and said fluid housing means;

the improvement comprising:

a first cylindrical tubular wall means coaxially positioned within said housing means for defining,

an inlet chamber within said tubular wall means, and an outlet chamber exterior of said tubular wall and interior of said fluid housing means, said outlet chamber circumferentially extending about said tubular wall means;

a cylindrical sleeve of volumetrically compressible material positioned within said inlet chamber about and disposed in full contact with said first tubular wall means for attenuating fluid pulsations within said inlet chamber;

a second cylindrical wall concentrically extending radially outwardly of said tubular wall means to define a concentrically annular fluid outlet chamber;

a cylindrical sleeve of volumetrically compressible material positioned within said outlet chamber contiguously extending about said second cylindrical wall for attenuating fluid pulsations within said outlet chamber;

conduit means extending between and placing in fluid communication said inlet port and said inlet chamber;

valve plate means mounted between said diaphragm and one end of said coaxial tubular wall means and defining a pumping chamber coaxially extending above said inlet chamber and said outlet chamber, said valve plate having

a plurality of inlet ports communicating between said inlet chamber and said pumping chamber, and a plurality of outlet ports communicating between said pumping chamber and said outlet chamber;

first valve means operably covering said inlet ports for permitting fluid to flow from said inlet chamber into said pumping chamber but preventing fluid from flowing from said pumping chamber into said inlet chamber;

second valve means operably covering said outlet ports for permitting fluid to flow from said pumping chamber into said outlet chamber but preventing fluid from flowing from said outlet chamber into said pumping chamber, whereby upon actuation of said motor said eccentric mounted connecting rod will serve to reciprocate said diaphragm coaxially with said inlet chamber to draw fluid through said conduit means into said inlet chamber, past said first valve means into said pumping chamber, and force fluid from said pumping chamber past said second valve means into said circumferential outlet chamber and out said exit port.

2. An improvement in a diaphragm pump as defined in claim 1 wherein:

said volumetrically compressible cylindrical sleeve within said outlet chamber and said volumetrically compressible cylindrical sleeve within said inlet chamber each are composed of a closed cell silicone rubber foam.

3. In a diaphragm pump including,

a frame means;

a motor connected to said frame means;

a connecting rod eccentrically mounted at one end thereof to a drive shaft of said motor;

fluid housing means mounted upon said frame means, including

a fluid entry port, and

a fluid exit port; and

flexible pump diaphragm means affixed to said connecting rod at the other end thereof and intercalated between said frame means and said fluid housing means;

the improvement comprising:

a first cylindrical tubular wall means coaxially positioned within said housing means for defining an inlet chamber within said first cylindrical wall means;

a second cylindrical wall means concentrically extending radially outwardly of said first wall means to define a concentrically annular fluid outlet chamber exterior of said first cylindrical wall and interior of said second cylindrical wall means, said outlet chamber circumferentially extending about said first cylindrical wall means;

a cylindrical sleeve of volumetrically compressible material lining said first cylindrical wall means within said inlet chamber for attenuating fluid pulsations within said inlet chamber;

a cylindrical sleeve of volumetrically compressible material positioned within said outlet chamber contiguous about said second cylindrical wall for attenuatig fluid pulsations within said outlet chamber;

said volumetrically compressible cylindrical sleeve within said outlet chamber and said volumetrically compressible cylindrical sleeve within said inlet chamber each are composed of a closed cell silicone rubber foam;

a cylindrical filter screen coaxially positioned within said inlet chamber in a posture contiguous to and interiorly of said cylindrical sleeve of volumetrically compressible material within said inlet chamber for supporting said sleeve within said inlet chamber and for filtering foreign matter from fluid entering said inlet chamber;

conduit means extending between and placing in fluid communication said inlet port and said inlet chamber;

valve plate means mounted between said diaphragm and one end of said coaxial tubular wall means and defining a pumping chamber coaxially extending above said inlet chamber and said outlet chamber, said valve plate having

a plurality of inlet ports communicating between said inlet chamber and said pumping chamber, and a plurality of outlet ports communicating between said pumping chamber and said outlet chamber;

first valve means operably covering said inlet ports for permitting fluid to flow from said inlet chamber into said pumping chamber but preventing fluid from flowing from said pumping chamber into said inlet chamber;

second valve means operably covering said outlet ports for permitting fluid to flow from said pumping chamber into said outlet chamber but preventing fluid from flowing from said outlet chamber into said pumping chamber, whereby upon actuation of said motor said eccentric mounted connecting rod will serve to reciprocate said diaphragm coaxially with said inlet chamber to draw fluid through said conduit means into said inlet chamber, past said first valve means into said pumping chamber, and force fluid from said pumping chamber past said second valve means into said circumferential outlet chamber and out said exit port;

said cylindrical sleeve of volumetrically compressible material positioned within said inlet chamber is cut at one end by an inclined plane; and

a landing column is fashioned within the interior of said inlet chamber in a posture diametrically opposed to said conduit means extending into said inlet chamber, whereby the greatest height of said cylindrical sleeve is operable to rest upon said landing column and be supported thereby while the shortest height of said cylindrical sleeve longitudinally extends above the opening of said conduit means and wherein said cylindrical sleeve of volumetrically compressible material is held in a circumferential posture adjacent the inlet ports within said valve plate.

4. In a diaphragm pump including

a frame means;

a motor connected to said frame means;

a connecting rod eccentrically mounted at one end thereof to a drive shaft of said motor;

fluid housing means mounted upon said frame means, including

a fluid entry port, and

a fluid exit port; and

flexible pump diaphragm means affixed to said connecting rod at the other end thereof and intercalated between said frame means and said fluid housing means;

the improvement comprising:

tubular wall means coaxially positioned within said housing means for defining,

an inlet chamber within said tubular wall means, and an outlet chamber exterior of said tubular wall and interior of said fluid housing means, said outlet chamber circumferentially extending about said tubular wall means;

a sleeve of volumetrically compressible material lining the interior wall of said tubular wall means for attenuating fluid pulsations within said inlet chamber;

conduit means extending between said and placing in fluid communication said inlet port and said inlet chamber;

valve plate means mounted between said diaphragm and one end of said coaxial tubular wall means and defining a pumping chamber coaxially extending above said inlet chamber and said outlet chamber, said valve plate having

a plurality of inlet ports communicating between said inlet chamber and said pumping chamber, and a plurality of outlet ports communicating between said pumping chamber and said outlet chamber;

first valve means operably covering said inlet ports for permitting fluid to flow from said inlet chamber into said pumping chamber but preventing fluid from flowing from said pumping chamber into said inlet chamber;

second valve means operably covering said outlet ports for permitting fluid to flow from said pumping chamber into said outlet chamber but preventing fluid from flowing from said outlet chamber into said pumping chamber, whereby upon actuation of said motor said eccentric mounted connecting rod will serve to reciprocate said diaphragm coaxially with said inlet chamber to draw fluid through said conduit means into said inlet chamber, past said first valve means into said pumping chamber, and force fluid from said pumping chamber past said second valve means into said circumferential outlet chamber and out said exit port.

5. An improvement in a diaphragm pump as defined in claim 4 and further comprising:

a volumetrically compressible material positioned within said outlet chamber for attenuating fluid pulsations within said outlet chamber.

6. An improvement in a diaphragm pump as defined in claim 5 wherein:

said volumetrically compressible cylindrical sleeve within said outlet chamber and said volumetrically compressible cylindrical sleeve within said inlet chamber each are composed of a closed cell silicone rubber foam.

7. In a diaphragm pump including,

a frame means;

a motor connnected to said frame means;

a connecting rod eccentrically mounted at one end thereof to a drive shaft of said motor;

fluid housing means mounted upon said frame means, including

a fluid entry port, and

a fluid exit port; and

flexible pump diaphragm means affixed to said connecting rod at the other end thereof and intercalated between said frame means and said fluid housing means;

the improvement comprising:

a first cylindrical tubular wall means coaxially positioned within said housing means for defining,

an inlet chamber within said tubular wall means, and an outlet chamber exterior of said tubular wall and interior of said fluid housing means, said outlet chamber circumferentially extending about said tubular wall means;

a second cylindrical wall concentrically extending radially outwardly of said tubular wall means to define a concentrically annular fluid outlet chamber;

a cylindrical sleeve of volumetrically compressible material positioned within said outlet chamber contiguously extending about said second cylindrical wall for attenuating fluid pulsations within said outlet chamber;

conduit means extending between and placing in fluid communication said inlet port and said inlet chamber;

valve plate means mounted between said diaphragm and one end of said coaxial tubular wall means and defining a pumping chamber coaxially extending above said inlet chamber and said outlet chamber, said valve plate having

a plurality of inlet ports communicating between said inlet chamber and said pumping chamber, and a plurality of outlet ports communicating between said pumping chamber and said outlet chamber;

first valve means operably covering said inlet ports for permitting fluid to flow from said inlet chamber into said pumping chamber but preventing fluid from flowing from said pumping chamber into said inlet chamber;

second valve means operably covering said outlet ports for permitting fluid to flow from said pumping chamber into said outlet chamber but preventing fluid from flowing from said outlet chamber into said pumping chamber, whereby upon actuation of said motor said eccentric mounted connecting rod will serve to reciprocate said diaphragm coaxially with said inlet chamber to draw fluid through said conduit means into said inlet chamber, past said first valve means into said pumping chamber, and force fluid from said pumping chamber past said second valve means into said circumferential outlet chamber and out said exit port;

a cylindrical sleeve of volumetrically compressible material positioned within said inlet chamber for attenuating fluid pulsations within said inlet chamber;

said volumetrically compressible cylindrical sleeve within said outlet chamber and said volumetrically compressible cylindrical sleeve within said inlet chamber each are composed of a closed cell silicone rubber foam; and

a cylindrical filter screen coaxially positioned within said inlet chamber in a posture contiguous to and interiorly of said cylindrical sleeve of volumetrically compressible material within said inlet chamber for supporting said sleeve within said inlet chamber and for filtering foreign matter from fluid entering said inlet chamber.