US2904876A - Shaft end mounting for sealing and loop forming a pump diaphragm - Google Patents

Description

Sept. 22, 1959' J. 1.. EDELEN 2,904,876 SHAFT END MOUNTING FOR SEALING AND LOOP FORMING A PUMP DIAPHRAGM 2 Sheets-Sheet 1 Filed May 12,. 1954 IVIIVIIIIIlI/l' W4] IIIIIIIIIL 'IIIIIIIIIII,

INVENTOR. JAMES L. EDELEN ATTORNEY Sept. 22, 1959 J. L. EDELEN 2,904,876

' SHAFT END MOUNTING FOR SEALING AND LOOP FORMING A PUMP DIAPHRAGM Filed May 12, 1954 2 Sheets-Sheet 2 X) q 30 l 4o 3 25 vI" l G. 3.

INVENTOR. JAMES L. EDELEN BY W ATTORNEY United States Patent SHAFT END MOUNTING FOR SEALING AND LOOP FORMING A PUMP DIAPHRAGM James L. Edelen, Kirkwood, Mo., assignor, by mesne asslgnments, to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey Application May 12, 1954, Serial No. 429,343

3 Claims. (Cl. 29-1564) This invention relates to diaphragm type of pumps and, more specifically, to a sub-assembly used in such pumps, including a mounting stem, diaphragm, and retainer. I

It is well understood that in pumps of this kind service life depends in good measure upon the proper mounting of the diaphragm in the pump, and this, in turn, depends upon the right amount of initial loop provided and proper pressure of the backing plates on the diaphragm to prevent any leakage between the diaphragm and the stern. This pressure, however, should be limited to avoid any stresses which might contribute to premature failure of the diaphragm. It is therefore desirable that the pressure between the backing plates during the assembly be carefully controlled.

'Heretofore it has been common practice to assemble the backing plates and diaphragm on the stem of the pump by a spinning or forging operation to head-over the end of the stem into engagement with the uppermost of the backing plates. In this operation, the final sealing pressure obtained between the backing plates and the diaphragm will depend upon initial dimensions of the assembled parts as much as on the accuracy with which the spinning or forging operation is performed. In quantity production this sealing pressure cannot be accurately controlled.

This invention is aimed at obtaining more uniform pressure between the backing plates during assembly of the stem to the diaphragm and plates. It is also the object of the invention to preset the desired amount of loop in the portion of the diaphragm externally of the backing plates and simultaneously with the assembly operation of the stem with the diaphragm and plates. This avoids any strain due to the action of the pump except that imposed by the pressure of the fluid and at the same time makes unnecessary the assembly step of presetting the loop.

According to this invention, the stem for the pump is provided with the usual reduced section for receiving the backing plates and diaphragm, whereby a substantial supporting shoulder is formed. The backing plates, however, are themselves modified from usual construction to provide oppositely facing, concave surfaces. In order to provide uniform pressure between the backing plates and the diaphragm, a novel keeper washer is forced into locked engagement with a tapered groove formed in the reduced end portion of the stem. This keeper washer is produced by deforming a flat washer into a conical shape. To assemble the washer in securing relation with the groove in the stem, pressure is applied at the outer rim of the conical washer sufficient to exceed the yield point of the metal. As the washer begins to flatten under the pressure, the outer peripheral edge of its aperture grips with the taper of the groove on the stern. This requires a force of given amount, depending, of course, upon the dimensions and material of the washer. These variables can be chosen to assure the desired amount of sealing pressure necessary. It has been found ice that this force is relatively uniform once these variables are determined. After the gripping action takes place, the force necessary to flatten the washer diminishes rapidly, and a rocking action radially of the washer takes place acting as a lever against the upper backing plate.

When the force required again approaches the pressure at the yield point of the metal, the operation is discontinued.

The results achieved so far with this method using the described structure have produced uniform pressure and a stretching action on the diaphragm sufficient to provide the performed amount of loop desired.

In the drawings:

Fig. 1 is an environmental view of one type of dia- Phragm p p;

Fig. 2 is an exploded View illustrating the arrangement of the parts for assembly with the stem;

Fig. 3 illustrates the position of the parts in the initial stages of assembly; and

Fig. 4 illustrates the relation of the parts when finally assembled.

Referring to Fig. 1, a body casting 1 contains a pump lever housing 2 provided with a flange 3 for attachment to the engine. A pump operating lever 4 having a slidable shoe 5 is pivoted at 6 within the housing 2. Pump lever 4 operates a pair of diaphragm pumps generally indicated as 10 and 11. These pumps are of the type shown in the patent to Hollembeak et aL, No. 2,623,351, December 30, 1952.

The pump 11 has a valve casing 13 containing an inlet connection 14 and an outlet connection 15. The inlet connection 14 connects with a pump chamber 16 by way of a passage 17 controlled by an inlet check valve 18. Discharge from the pump chamber 16 is controlled by an outlet check valve 19 in the outlet passage 20.

Within the pump chamber 16 is a diaphragm assembly generally indicated as 25, which includes a reciprocal stem 26 operated from the pump arm 4 in one direction and the compression spring 27 in the opposite direction. The stem is secured to a diaphragm 30, which is, in turn, clamped at its peripheral edge between the pump body casing 1 and the valve casing 13. Any suitable securing means may be used to attach these parts together.

The present invention is concerned with the novel features and method of manufacturing the sub-assembly 25.

In order to illustrate the details of this sub-assembly, the drawings show an exploded view in Fig. 2 with the parts arranged in the manner to be assembled upon the stem 26. Turning to this figure, the stem 26 is illustrated as cylindrical with a reduced end portion 35 forming a supporting shoulder 36. Formed in the upper end of the reduced portion 35 is a groove 37 with a double taper. The groove 37 is intentially designed so that the widest shoulder with the gradual taper faces the shoulder 36.

The elements which are assembled on the stem 26 in clude a plain washer 39, a lower backing plate 40, diaphragm 30, sealing washer 41, upper backing plate 42, upper backing washer 43, and the conical keeper washer 45.

In the assembly of the parts above enumerated, the washers, backing plate, diaphragm, and keeper are assembled upon the stem as shown in Fig. 3. As will be noted in this figure, the backing plates are dished slightly, and it has been found that preferably this concavity should be .012 to .020 of an inch. The keeper washer 45 is a plain, flat washer pressed into conical form. The sub-assembly with the parts arranged in the manner described mounted in a holder 48 are inserted in a press of any desired type which will indicate the pressure applied. The press member"49is a die having a cavity 50 deep enough to receive the keeperwasher-45, andis of a diameter at the bottom of the concavity the same as the original diameter of the keeper washer 45 before the coning operation. 'The "sides '51'of' the cavity50 preferablyhave about a taper.

'In'the assembly operation, --as-pressure-is appl-iedby the die'49 with the sub-assembly 2'5" suitably mounted'in the holder 48 on-the anvil of the press, the-conical washer movesdown to the groove 37 and the backing plates are flattened'to tension-the diaphragm. Pressure then increases until the yield point in the metal'of'the washer 45 is reached, thereby causingthe-size of the aperture in the washer to be decreased. Thispressure will be sufiicient to flattenthewasher andcausethe outer edge of its aperture to contract and gripthe -tapered shoulder of the groove 37. During the compression of the'washer-45,-the action of the'backing plates to stretch the diaphragm centrally in a radial direction is completed. This forms the desired loopingnecessary to accommodate the stroke of the pump.

After'the yieldpoint of the washer '45 is reached, the pressure necessary to flatten the washer suddenly decreases and, as the washer flattens, it 'acts as a lever'pivoting about the outer edge of its aperture, which is in gripping engagement with the groove. The press operation is continued until the pressure necessary to continue the flattening of the washer approaches that required at the yield point of the'metal, at which point the washer appears'as shown in Fig. 4 locked in final position.

The sub-assembly 25 is then complete and ready for assembly in the pump.

The small sealing washer 41 has beenfound tobe desirable because, duringthe radial stretching of the diaphragm '30, the aperture receiving'the stem 35 is enlarged and, without the sealing washer, a space would be left to permit leakage around the stem. The sealing washer fills this' space and prevents leakage.

It has been found that the'invention provides uniform results in spite'of minor variations in thickness of the parts. These variations can be accommodated by-the latitude provided on the-shoulder 37 for receiving'the keeper washer 45.

A structure has been described which will fulfill the objects ofthe invention above stated, but it is contem- 'said assembly, and applying pressure to the rim "portion of the washer in a'dire'ction to'flattensamewhile the'rim portion is confined to maintain apredetermine'd diameter, to'therebycompress the washer until ittightly engages the stem..

2. The method'of clamping anassembly of two backing plates and a diaphragm therebetween against a shoulder on a pump stem, which comprises forming an annular tapered seat 'onsaid stem converging toward said shoulder, mounting -'a dish-shaped -wa'sher ow said stern for engagement against said assembly, and applying pressure to the rim portion of the washer in a direction to'fiattensame'whilethe rim portionisconfined to maintain'a pre'detern'iineddiameter,'to thereby compress the washeruntil it tightly-engages the tapered "seat'onthe stem.

3. A method-accordingto claim -2,in which said two backing plates are formed dish-shaped for initial annular clamping engagement with said diaphragm adjacent-their outer peripheries.

References Cited in the file of this patent UNITED STATES PATENTS 1,847,457 'Zeibig Mar. 1, 1932 2,036,452 Babitch Apr. 7, 1936 2,209,181 -Wendel July 23, 1940 2,537,241 Smith Jan. 9, 1951 2,564,372 Phelps et a1 Aug. 14, 1951 FOREIGN PATENTS 120,409 Australia Sept. 25, 1945 708,743 :France May 4, 1931

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