US2634687A - Pump device - Google Patents

Description

April 14, 1953 s l 2,634,687

PUMP DEVICE Filed March 11, 1949 50 l5 I8 25' 26 2a /0 INVENTOR. RUSSELL F. SMITH Patented Apr. 14, 1953 PUMP DEVICE Russell F. Smith, St. Louis, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a. corporation of Delaware Application March 11, 1949, Serial No. 80,943 Claims. (Cl. 103-150) This invention relates to diaphragm or expansible chamber pumps of enclosed type, suitable for use in fuel systems of automotive internal combustion engines and the like, and concerns more particularly, the provision of novel and effective breather or pressure relief means for such pumps. The pressure relief means according to the present invention, is especially suitable for application to an enclosed diaphragm type fuel pump of the character shown in and forming the subject of, an application, Serial No. 728,979, filed February 17, 1947, by Irven E. Coffey.

In pumps of the character indicated and particularly of the form shown in the application referred to above, protection of the diaphragm against damage and the deleterious effects of dust, dirt and other foreign matter, is accomplished by constructing the pump casing to afford a closed chamber on the side of the diaphragm opposite the pumping chamber, with the diaphragm actuating member or stem sealed in its passage outwardly of such chamber. Obviously, it is necessary in a pump of this character, to afford a vent or pressure relief means for the closed chamber and to that end, it has been the usual practice heretofore, to provide an atmospheric vent opening in the casing portion defining the closed, protective chamber, with a suitable screen or filter element in the vent opening. However, it has been found in practice, that a screened vent having a capacity adequate for pressure relief of the chamber in pump operation, is not effective to exclude all dirt, but will admit fine dust and other foreign matter of a fineness to pass through the mesh openings of the screen. Moreover, because, of the rapid pulsation of the pump diaphragm in normal operation, there is a tendency for the screened vent to act somewhat as a whistle valve, in pressure relief of the closed chamber, thereby tending to create an undesirable noise condition in pump operation.

Accordingly, it is the principal purpose of the present invention, to overcome the foregoing and other disadvantages attending the use of screened relief vents in pumps of the character indicated, by the provision of a novel, noiseless pressure relief or breather device which will exclude all dirt, dust and other foreign matter.

Another object is to provide a pressure relief or breather device for pumps of the type indicated, comprising a nipple on the casing and a bulbous element formed of a flexible and expansible material, in sealed engagement with the nipple, wherein the bulbous element afiords an expansible chamber in communication with the closed, diaphragm protecting chamber of the pump.

Other objects and advantages of the present invention will appear from the following description of a presently preferred embodiment thereof, as exemplified in the drawing. The single figure of the drawing illustrates partly in elevation and partly in section, a closed diaphragm pump embodying the breather device of the invention, the breather device being shown in sectional elevation.

While the pressure relief means of the present invention is readily applicable to various forms of fluid pumps of the general character indicated, it is preferred here to illustrate the same in application to an enclosed diaphragm type fuel pump corresponding in form and construc-- tion, to the fuel pump shown in the application hereinabove identified. However, in the present exemplary disclosure, only those parts of the pump assembly which are helpful and essential to an understanding of the invention, are shown.

Referring to the drawing, the pump includes a casing provided by the casing sections [0 and H having complementary marginal flanges l2 and I4, respectively, through which the sections are connected in assembly as by the screws l5. Clamped between the casing flanges is the marginal portion 16 of a flexible diaphragm IS, the diaphragm defining with the casing section Ill a pumping chamber 19, and with the casing section II a chamber 20. Although not shown, suction and discharge control valves together with intake and outlet passages, are arranged in casing section III, in operative relation to the pumping chamber I9.

The central portion of the diaphragm is disposed between subtsantially dish-shape backing plates 22 and 23 which are held in assembly to the diaphragm, through washers 24 and 26 engaged respectively, by shoulders 21 and 28 on the inner end 30 of a diaphragm actuating member or stem 3|. The end 30 of the stem passes through the washer, plates and diaphragm, while the shoulders 21 and 28 thereon, serve to clamp the parts in relative assembly and to connect the diaphragm structure to the stem for actuation thereby.

Stem 3| extends centrally through chamber 20 and has its opposite end portion 32 projecting outwardly of the chamber through an opening 34 in chamber end wall 35, for operative asso ciation with one end 36 of an actuating lever 38. The lever end 36 is adapted for embracing the stem adjacent a bumper head structure 39 on the outer end of stem portion 32. Pivotally supporting the lever at a point intermediate its ends, is a pin 40, the pin in turn being suitably supported in the base portion 42 of a pump mounting bracket 43. As here shown, the bracket 43 preferably is provided as an integral, lateral extension of the casing section [I at its outer end, and is adapted through its base portion 42, for mounting on an engine such as to dispose the projecting end 44 of the lever in 'engagement with an engine driven, pump operating cam (not shown) cam-contact by a spring 46 arranged as shown.

In the pump illustrated, cam actuation of the lever to raise the end 36 thereof, effects the suction stroke of the diaphragm through upward displacement of the stem 3| and a corresponding displacement of the diaphragm to enlarge the pumping chamber I9. The discharge or pumping stroke of the diaphragm is produced by a coil spring 4! of suitable capacity, arranged in chamber 20 between the diaphragm, plate 22 and the end wall 35 of the chamber. Spring 41 yields on the suction displacement of the diaphragm, and expands as the actuating cam relieves the lever 38, to effect the pressure stroke of the diaphragm.

The casing section H protects the diaphragm against damage, and since it is important to continued functioning of the diaphragm, to exclude dirt, dust and other foreign matter from access to the chamber 20 formed by the casing section I I, provision is here made to close the stem opening 34 of the chamber. To this end, there is provided a sealing diaphragm 50 of flexible material, such as synthetic rubber, having its peripheral margin clamped between the rim' portions of opposed backing elements 52 and 54, the latter together with the margin of wall diaphragm 50, being suitably held in assembly adjacent casing wall 35 about opening 34, against a sealing gasket 53 interposed between the wall and element 54. In the present example, backing element 52 affords a seat for the end of spring 41, the spring thereby serving to retain the backing elements and sealing diaphragm in place. The central enlarged portion 56 of diaphragm 50 frictionally embraces the stem 3| and hence follows the movements of the stem in pump operation. This sealing means is covered in an application, Seriallflo. 726,186, filed February 3, 1947, by Irven E. Coffey, now Patent No. 2,567,055.

.Withthe above arrangement, it is necessary to provide for a breather or pressure relief action for chamber 20.

As shown in the drawing casing section II is provided with a rimmed boss or nipple 60 having passage 66 extending centrally therethrough in communication at its inner end with. the chamber 20. A flexible and expansible bulb 10 has a neck portion 12 with a marginal bead l4 tightly received on the nipple and with its interiorcommunicating through passage 66 with chamber 20.

In pump operation, when the pump diaphragm is at the end of its pressure stroke, as shown in the drawing, bulb I is contracted as'to the solid line position shown. Displacement of the diaphragm in its suction stroke, decreasesi the volume of chamber 20 and thereby tends to cornpress the air trapped in the chamber, the nipple passage 66 and the interior of thebulb. Thereupon, the bulb will expand in response to'air The lever is yieldably held in 4 displacement by the diaphragm, such as to increase its volume in proportion to the decrease in the volume of chamber 20, which thereby effectively relieves pressure in chamber 20 such that the pressure therein is approximately or only slightly in excess of atmospheric pressure. When the diaphragm attains the end of its suction stroke, as to the pha'n tom "or broken line position shown, the bulb 'Hl will have expanded substantially to the broken line position shown. From the foregoing, it will appear now that although chamber 20 is fully sealed from the surrounding atmosphere pulsations of diaphragm 181C1 0 not materially'affect the pressure in chamber '20 applied to the non-pumping face of the diaphr a gm. Obviously, the arrangement thus precludes entrance of dust, dirt and other foreign matter to chamber 20, while affording full pressure relief of the chamber through the expansible breather 'lfl. Importantly also, since bulb 1,0 is of a flexible and expansible character, and the nipple passage 66 is of relatively large 'diameter, the breather deviceasconstituted by these elements, is substantially noiselessin its function.

The bulb may 'be formed of 'a suitable synthetic rubber or other similar -material having the desired degree of flexibility and expansion for pump breather application as herein disclosed. Moreover, it is constructed such that its volumetric capacity in expansion to a dagree well below the rupture point of the material, is elitirely sufficient to accommodate the full volumetric contraction of chamber 20 consequent to displacement of the pump 'diaphragm inwardly 'of the chamber to the end of its inward or suction stroke. Further relative to the construction of'the element, the thickness of the efiective wall portion ill thereof, is held to a minimum so that it may readily expand and contract at a rate corresponding to the cyclic rate of pump diaphragm displacementfthe latter in the instance of an engine driven 7 fuel pump, being of theorder of 2 000 cycles 'per minute. a The bulb 70 arranged externally of the pump casing section II in frictional assembly to the nipple BB, is thereby'readily accessible for replacement in the event of "damage to the element,

Having 'now described and illustrated a presently preferred embodiment "of the invention, it is to be understood that various alterationsand modifications ofthe embodiment shown, may be made without departing from the spirit andfull intended scope of the invention, as defined bythe appended claims.

Iclaim: a v 1. In a pump, a movable pumpingwall, a'pump chamber and a protective chamber exposedjto opposite sides of'said wall, and' a pressure relief device for said protective chamber, comprising an expansible element mounted'in'a wall'ofsafid protective chamber andcapableof substantially increasing the volume of said latterfcharnb'er. 2. In 'a pump having 'a'pumping' diaphragm and a casing forming'a pump chamber and 'a protective chamber at opposite sides of said diaphragm, said diaphragm constituting one wall of each of said chambers, pressure relief means for said protective chamber comprising a"n'ipple on the casing, anda bulbous, expansibl'e'el'ement on said'nipple, said nipple having a 'p'ass'agfconnecting the interior of thebulbous element to said protective chamber. a v V v 3. In'apump of the character described; having a casing and pump-diaphragm assembly providing a pump chamber and a protective chamber for the diaphragm, wherein the diaphragm constitutes one wall of said protective chamber, breather means for said protective chamber comprising a bulbous element formed of flexible and expansible material, providing an expansible chamber, and means mounting said expansible chamber element on the casing in communication with said protective chamber.

4. In a pump providing a casing and a pumping diaphragm therein, defining with the casing a pumping chamber and a diaphragm protective chamber on opposite sides of the diaphragm, a diaphragm operating element extending through said protective chamber and outwardly through a wall of the chamber, and a seal at the extension of said element through said wall, closing the chamber, the combination therewith of pressure relief means for said protective chamber, comprising an expansible chamber device mounted on the casing and communicating with the protective chamber.

5. In a pump providing a casing and a pumping diaphragm therein, defining with the casing a pumping chamber and a diaphragm protective chamber on opposite sides of the diaphragm, a diaphragm operating element extending through said protective chamber and outwardly through a wall of the chamber, and a seal at the extension of said element through said wall, closing the chamber, the combination therewith of pressure relief means for said protective chamber, comprising a projection on the pump casing providing an external shouldered seat, a bulbous element of a flexible and expansible material, having a neck portion mounted on said shouldered seat, said bulbous element forming an expansible chamber, and said projection having a passage therethrough communicating the expansible chamber with said protective chamber.

RUSSELL F. SMITH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,713,073 Carter May 14, 1929 1,737,289 Redmond Nov. 26 1929 2,254,495 Randolph et a1 Sept. 2, 1941 Babitch et a1. Jan. 12, 1943

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