US2372302A - Deformable diaphragm for pumps and the like - Google Patents

Description

March 27, 1945. N SWIND'INY 2,372,302

DEFORMABLE DIAPHRAGMS FOR PUMPS AND THE LIKE 7 Filed Aug. 15, 1942 5 Sheets-Sheet l jiventor Vorman Swz'ndz'n N. swm'om March 27, 1945.

DEFORMABLE DIAPHRAGMS FOR PUMPS AND THE LIKE Filed Aug. 15, 1942 3 Sheets-Sh eet 2 w QM ihvntor Norman SWl'ndzn March 27, '1945.

- N- swmom 2,372,302

DEFORMABLE DIAPHRAGMS FOR PUMPS AND THE LIKE .Filed Aug. 15, 1942 5 Sheets-Sheet 3 mmmmmmm hT/CTLYOJ .Narmom Swzndz'n Patented Mar. 27,1945

DEFORMABL-E DIAPHRAGM FOR PUMPS AND THE LIKE.

Norman Swindin, London, England, assignor to Nordac Limited, London, England, a British company Application August 15, 1942, Serial No. 454,888 In Great-Britain July 24, 1941 3 Claims. (Cl. 137-156.5)

This invention comprises improvements in. or

relating to deformable diaphragms for pumps and the like. It is an object of the inventionto provide a pump which is capable of dealing effectively with acid or other corrosive liquors, even when these have to be pumped against a con siderable head, and which avoids the use of glands and other fitments where leakage is liable to occur. One usual method of dealing with acids and the like is by an. acid egg but. this involves the use of compressed air; another method is to employ a rubber-lined centrifugal pump but this necessitates a gland around the spindle of the pump; pumps working by means ofdia- .phragm or bellows are normally very bulky in relation to their delivery.

According to one feature of the present invention a pump comprises a pumping chamber having a wall which consists of deformable rubher or like material in. combination with means 7 to vary the volume of the pumping chamber periodically by alternately contracting and expanding the wall in a direction parallel to its face. i

It will be appreciated that the expression. expanding and contracting the wall in a direction parallel to its face is intended to distinguish from diaphragm pumps in whichthe rubber diaphragm is deformed substantially at-right angles to its face. to this invention to be expanded and contracted parallel to its face by a movement which includes both a component parallel to the face and a component in another direction, so long as the main effect is due to the enlarging and shrinking of the face of the rubber or the like. 7

Preferably the deformable wall of the pumping chamber is circular in form and is compressible in an axial direction by a reciprocable end plate. The circular wall maybe built up from a num-' ber of rubber rings resting one upon the other and united by vulcanizing them together into one whole.

Preferably the outer surface of the wall of the pumping chamber is largely restrained from lateral expansion. while under compression. by uniting the outer wall to metallic rings which are spaced at intervals around the wall outside the pumping chambers.

Under the term rubber or like material there is included in this specification any resilient material of a rubbery consistency, especially including synthetic rubber such as Neoprene, Buna, and admixtures of such materials with rubber.

It is possible for the wall according It is an important feature of the invention that if the pumping chamber is built up from circular rings which enclose the chamber within them and are themselves surrounded by metal restraining rings, when the wall is compressed endwise the rubber is caused to bulge radially inwards by its faculty for lateral expansion while under comthe same time and according to the present invention. constitutes a pressure resisting diaphragm or bellows although it cannot strictly be described as a bellows inasmuch as the wall is not corrugated. This form of diaphragm or partition is not only applicable in a pump for corrosive liquids or gases but can also be applied .to other cases, where bellows or diaphragms are commonly employed such as in the manufacture of valves. Acid resistant valves are commonly made with a bellows to permit movement of the valve member requiring a sliding valve-operating rod moving through a stuffing box and the substitution of a deformable wall in accordance with the present invention for the bellows or diaphragm usually employed permits the valve to be used on much higher pressures.

The following is a description by way of ex ample of certain constructions in accordance with the invention reference being made to the accompanying drawings, in which:

Figure 1 is a cross section of pumping chamber and driving mechanism.

Figures 2 and 3 are cross sections of part of the pumping chamber showing details of construction and effect of compression 0n chamber walls.

Figure 4 is a cross section of a pumping chamher and valves suitable for compressing gases.

A hollow box-like base, I 5, Figure 1, is pro vided containing bearings l6 for a crankshaft I! and an appropriate system of lubrication l8. The crankshaft spans the interior of the base near the bottom thereof and in the upper part of the base there is a central cylindrical guide l 9, within which works a trunk crosshead 28 similar to an engine piston. In the crosshead is a gudgeon pin 2! and'a connecting rod 22 serves to drive the crosshe-ad 20 from the. crankshaft ll.

On the base there is secured a cylindrical pump chamber casing 23 which is flanged at the top outwardly. On the flange rests a rubber .covered intermediate flange 24 belonging to the pump chamber proper It] and on the intermediate flange 24 there rests a top flange 25 of the body 64, which carries lateral connections for inlet andoutletvalves. (not shown). Both the interior of the pump body 64 and the. lateral connections are rubber-covered.

The pumping chamber, tube or cylinder It is supported within the pump chamber casing 23 by the aforesaid intermediate flange 24.. This chamber tube or cylinder 10 is built up from a number of superposed rings of India rubber. l3 and it is closed at the bottom by a rubber-covered end plate 3|. The end plate 3| has a central boss 32 on the side remote from the pump chamber l and is connected to the reciprocatingcrosshead 2D in the base I5 by means of an intermediate compression member 33 whichconnects the boss 32 and the crosshead Zfl with a right and left-hand thread so that the setting can be adjusted. Each of the rubber rings 13 has a cylindrical internal face and parallel top and-bottom faces. Each ring 13 is vulcanized to a surrounding steel restraining: ring I4, the thickness of which in an axial direction is less than the thickness of the rubber-ring and the.

side diameter of the rubber rings I3. This washer 34 is covered with rubber on its inner part where it fits between therubber rings IS. The whole of'this assembly is Vulcanised together so that the rubber rings I 3 together with the Indiarubbe'r which covers the: intermediate washers 34 form one uniform internal rubber wall l2 to the pumping chamber In which is also united to the rubber-covered intermediate flange 24 at thetop and to the rubber-covered end plate 3-! at the bottom. One of the purposes of the thin washers 34, which are intermediate between the rubber rings, is to support the rubber during vulcanisation and to this end during the vulcanisation process the washers 34 are packed so that they are equidistantly spaced from the steel rings 14 which are vulcanised to the outside of the rubber rings l3. This packing is done by appropriate'metal wedges 0r shims in the form of split rings which are removed after-vulcanisation leaving the washers and the steel rings equally spaced from one another. It will therefore be seen that a considerable amount of endwise compression can be given to the pumping chamber H] (which is built up of the rubber rings l3, fused into one continuous external wall to the chamber) before the steel rings l4 have been brought into contact with one another. During compression the rubber forming the chamber is held from expanding outwardly'by the steelrings l4 and the intermediate washers 34 but is free to expand inwardly in a lateral direction into the chamber In. The chamber is therefore not only reduced in volumeby the reduction in its length but also by the bulging inwards of the walls, as shown in Figure 3. This two-fold reduction in volume of the pumping chamber H] is very similar to the action of the alimentary canal of animals and is known in medical circles as peristalsis.

A furtherpurpose of the steel washers 34 is' to divide the rubber wall 12 of the pumping chamber l0 into a number of separate rings in order to control and equalise distortion of the rubber under compression and also to conduct away heat that may be generated in the substance. of the. rubber due. to rapid compression when thepump is run at high speeds. It is essential that good adhesion be made between these steel rings 34 and the rubber rings [3 in order to produce a continuous wall incapable of separation.

In operation the spacing between the crosshead 20 and the bottom end plate 3! of the pumping chamber I0 is so adjusted that the Indiarubber is in slight compression when the crankpin is at the bottom of its stroke. A length of stroke is imparted to the crankpin which may be, say about one-sixth of the length of the pumping chamber Ill and the rubber is compressed to this extent during the upstroke of the crosshead 20, expanding again during the downstroke. Liquid is drawn into the pumping chamber through the inlet valve 26 at the top and fills the chamber during the operation of the pump. When the pump-chamber H! is quite full liquid is forced out On the upstroke through the outlet valve 21. It will be observed that the whole of the interior of the pumping chamber ID in cluding the top valve and casing 64 is rubber lined so that the pump can handle acids or any liquid the rubber is capable of withstanding; also that there is no relative movement of the walls at any point and consequently no glands or packingis necessary. A pump of this description can operate at a fairly high speed" of reciprocation; the stress on the reciprocating parts is always inone direction so that backlash between the limits of working does not arise; owing to-the steelrings l4 surrounding the rubber pumping chamber l0 it can operate against a high pressure; and owing to the fact that the lateral expansion of the rubber is utilized as well as its direct compression, together with the high speed at which thepump can be worked, the capacity ofthe pump for a given size is reasonable.

It is necessary to ensure that the rubber pumping chamber I!) when under compression shall maintain itself in'a straight line. This is assisted by the crosshead 20 hereinbefore described but it can be further assisted, if desired, by guiding the movement of the external steel rings l4. These may be provided with eyes 36 at several places around their periphery which slide on vertical guide rods 31 mounted parallel to the movement within the pump-chamber casing 23.

It will be appreciated that while one particular form of pump has been described modifications may be readily be made-within the scope of the invention.

Figure 4 illustrates a pump suitable for use when dealing with corrosive gases. The rubberlined pump-chamber is built up in two parts. The upper part consists of a rubber-lined metal cylinder-Bl] having a flange 5| while the lower part of" the pump chamber consists of adeformable wall or cylinder built up of rubber rings l3, metal restraining rings l4 and metal washers 24 built up in the manner hereinbefore described, the metal rings l4 being provided with eyes at several places round their periphery and sliding on the vertical guide rods 31. The two halves of the pump chambers are bolted together through the intermediate rubber washers 52. The reciprocable end plate 53 is bolted to an ebonite plunger 54 and moves backwards and forwards therewith inside the bellows. The plunger is or such a diameter that it nearly fillsthe space within the bellows when the latter are compressed fully, and thus obviates the clearance space which would otherwise exist in chamber 50 and would prevent the pump from being effective on gases. The top Part 50 of the chamber is connected to the inlet passage 5Tand the outlet passage 58 through the inlet valve 55 and outlet valve 56 respectively. These may be rubber valves of well known type.

As shown in Figure 4 the plunger is at the end of its suction stroke, the, chamber and clearance spaces being then filled with the gas. On the return stroke the plunger 54 moves up to within tolerance limits of the end of the chamber and wall of the pump chamber is end plate 53 moves upward 0n the return stroke ofthe plunger the inlet valve 55 opens and gas is drawn into the chamber and at the same time the compressible part of the state. 7

having a wall which conf end plate secured to said wall, means to recipro- 2. In a pump for corrosive fluids, the combinawhich consists of deformable elastic material, an

cate the endplate so as to alternately compress and expand the said wall endwise, restraining rings around said wall partially substance of the wall and spaced at intervals 115 the gas is driven through the outlet valve 56 and i passage 58. During this operation the deformable" compressed as the? with the plunger.

guide-bars extending along it, and guide-bars extending parallel to the direction of movement: of the end plate and engaging each of the restraining rings to cause them to move in a straight line when the said wall is compressed, said wall being encircled by rigid washers at intervals located so as to alternate with the restraining ring 3. In a pump for corrosive fluids, the combination of a pumping chamber having a circular wall which consists of circular rings of rubber each of which carries a restraining ring around its outer periphery and between which are intercalated metal washers, the whole being vulcanised together, an end plate secured to said wall, means to reciprocate compress and expand the said wall endwise, and parallel to the direction of movement of the end plate and engaging each of the restraining rings to cause them to move in a straight line when the said wall is compressed.

NORMAN SWINDIN.

embedded in the I the end plate so as to alternately

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