US2610832A - Condenser - Google Patents

Description

Sept. 16, 1952 J. R. HOLMES ETAL CONDENSER Filed Aug. 2, 1947 ttorneg Sept. 16, 1952 J. R. HOLMES EI'AL 5 3 CQNDENSER Filed Aug. 2. 1947 2 SHEETS-SHEET 2 Patented Sept. 16, 1952 UNITED STATES PATENT OFFICE p a 2,61o,832 i v I -ONDENSER I john Ralph Holmes and Adolf Schwarz, Lockport, N. Y., assignors to General Motors Corporation, Detroit, Mich., acorporation' of Delaware p Application August 2, 1947, Serial No. '765,730

' s Clains. (01. 257-28) This invention relates to heat exchangers of the type employing a bundle of finned tubes supported at opposite ends by header plates and an object of the invention is to make feasible the use of relatively long tubesby additionally supporting and binding together the several tubes at one or more place intermediate their length for increased rigidity and a lessenng of indi- Vidual tube vibration and fatigue thereby -enabling thinner wall tubing to be used, V

In the particular embodiment to "be referred to the relatively long tubes carry exterior ns, which consist of helical windings of wire coils extending in one piece from end to end of each tube and the mutual' intersupport of ;the several tubes from one another and from their enclosing housing is easily and cheaply effected by fitting spacer sleeves to intermediate portions of the finned tubes, with each sleeve locked against axial displacement by a simple deformation in the fin portions near opposite ends of the spacers and with the neighboring spacer sleeves engaging one another and being crowded together within an encircling tensionable band firmly located by clamping abutments adjustably carried by the enclosinghousing. r V

A better understanding of, the structure will be had from the accompanying drawing wherein Figure l is an elevation of a long cylindrieal condenser structure having a portion of the, housing wall broken away and shown in section; Figure 2 is a transverse section on a larger scale, as on line 2-2 of Figure 1; Figure 3 is a longitudinal section, as on line 3-3 of Figure 2 and on a still larger sca1e; Figure ,4 is :anivenlarged transverse section of one; of the ;tube subassemblies as viewed on line 4--4 of Figure 3.; c L In the drawing abank of spaced; tubes l is illustrated as being enclosed withinla cylindrical shell or housing 2,' with each tubesupported at opposite ends by the header plates 3 and'4, the attachment of the tubes and header 'platesbeing efiectedby any suitable manner, such as by fitting the end into preformed openings ,in the header plate and by expanding or fiaring the tube end, as best seen in Figure 3. Secured 'to the header plate 3 is a domed cover, 5 containing two chambers with a coupling fittin'g s-zsfor each, one of the fittings being for the inletand the other for the outletof cooling fluid to flow through thetubes. To. the opposite. endrplate 4 there is Secured a domed cover 'l having a's'ingle chamber communicating withallthe tubes 'so that the cooling fluid fiowing rrom the .inlet chamber in the cover 5 and through one setof 2 the tubes I will be directed by the chambered cover 'l through the remaining set of tubes to the outlet chamber in the opposite end cover 5. Secured to the wall of the housing shell 2 are one or more inlet fittings 8-8 and cne or more outlet fittings e-a for the flow through the housing and around the outside of the tubes of the fiuid to be cooled, which in the case of a condenser for a refrigerating medium will enter the housing as a gas and upon being condensed will leave the housing as a liquid.

Each tube assembly prior to its mountin in the 'end plates will have fin formations formed thereon. The fnned tube subassembly, as shown in the drawing, includes the 'tube l formed of brass and having fixed thereon closely adjacent each end a steel collar IO held by extruding the tube against the collar and being coveredwith copper brazi'ng material and serving to anchor the opposite ends of the coiled fin ll. The fin is preformed by winding steel wire on a suitable mandrel and then copper flashed. One end of the coiled fin is then inserted in an opening through one of the end collars o and i peened tightly and then the coil is woun'd spirally around the tube entirely along the length of the tube to the opposite end collar 10 'into an opening of which the other end of the fin wire is inserted and peened tightly. Thereafter the tube assembly is placed in a brazing furnace whereby the parts are rmly joined together. After furnace brazing a spacer sleeve 12, preferably of a split ring type, whose internal diameter approximates or initially is slightly less than the external diameter of the fin ll is slipped from one endof the tube over 'the wire fins to a selected intermediate location on thetube assembly. `Its split ring construction 12' will enable whatever diametrical expansion and contraction is required to insure a tight fit to the perimeter of the wire fins even though a wide range of manufaeturing tolerance is prescribed for the fins. Following proper lengthwise location of the 'spacer sleeve l2 one or more coils in the fin convolution nearest each end of the sleeve are pinched or other wise deformed so'as tobe projected radially outr wardly as at !3 and thereby formstop abutments for cooperation with the sleeve ends to limit axial displacement of the sleeve;

Upon arranging a proper number of the tubes in a'group to fit'the size of the housing ;shell 2 and with each spacer sleeve in contact with spacer sleeveseof neighboring tubes, the assembly of tubes'is wrapped within an encircling band or metal strap |4 'which is placed under tension 3 to crowd the tubes together for their mutual inter-support, by means of a clamping screw bolt !5 joinin together the abutting opposite ends of the band I 4. The band preferably is a relatively thin flexible sheet strap to bend readily around the corners or otherwise conform to whatever peripheral Outline is defned by the tube bundle, whether polygonal sided as shown or otherwise. To afford ample hearing for the clamping screw 15, the ends of the strap are provided with thickened blocks !ES-!6, one having a tapped hole to receive the screw threads of the clamping bolt and the other having an apertured locating lug for the screw head. At inter- Vals around its circumference the contractible strap may be engaged by or have secured thereto additional thickened block portions or shoes l8` and the several blocks provide for distribution oi' radially inward pressure on the tube assembly transmitted by adjustable abutment elements carried by the housing. These abutments in the form illustrated consist of a series of set screws !3 threaded through the wall of the housing to engage the pressure distributing plate IS and thereby firmly locate and support the intermediate portion of the bank of tubes. After initially setting up the series of set screws IS they may be locked against accidental displacement by peening, soldering or otherwise. The inward contraction of the tube bank encircling structure will insure a snug fit of the spacer sleeves against each other with each split spacer being capable of further contraction under pressure imposed thereon to take out all looseness and insure a firm support for the intermediate portions of the relatively long heat exchanger tubes. A spacer and stiener bar 20 may, if desired, be positioned diametricaily of the encircling band M and midway between the group of tubes.

It will be noted from the drawing that the housing 2 is formed in sections, the main section being relatively long and joined for convenience by a torch brazing operation in end to end relation with the two short length end sections. The latter are brazed or otherwise'joined to the tube plates 3 and 4 containing the spaced apertures in which the tube ends are fitted. The joint between each tube plate and its adjacent housing end section is indicated in the drawing at 21, while the numeral 22 indicates the line of jointure between the respective housing end sections and the main housing shell. Dvison of the housing shell into sections eliminates the need for making a torch :brazed joint at 2 I after the tube plates are fitted to -the tubes as would be necessary in the final assembly of the tube plates to a single piece shell and the heat from which would tend to set up oxidation between the tube ends expanded into the tube plates. With the present structure the assembly of the condenser is conveniently eiiected by first furnace brazing the housing end sections to the plates at ZI. Thereafter one of the tube subassemblies has the tube ends of the previously finned and assembled bank of tubes tted and joined thereto and then the main housing section is slid over the tube bank from the opposite end' and the other tube plate subassembly is joined to the` opposite tube ends with the abutting portions of the shell sections tted together through internesting shouldered formation thereon, as seen in Figure 3. Thus the internested housing joints may thereupon be torch brazed at 22 without the likelihood of intense heat fiowing to and inducing oxidation at 4 the expanded and flared tube end joints with the tube plates.

We claim:

1. In a heat exchanger of the character described, a housing having a pair of tube plates, a bundle of finned tubes supported at opposite ends by said tube plates, and flexible means to support the tube bundle intermediate its ends, including spacer sleeves snugly embracing the finned tubes, each sleeve in abutment with adjacent sleeves on neighboring tubes, projecting formations on the tube fins immediately beyond the sleeves for locating the sleeves against axia displacement, a tube bundle encircling strap engaging the spacer sleeves on the outermcst tubes, strap tensioning means contracting the strap for crowding the sleeves in clamped together relation and a series of spaced seating abutments adjustably mounted in the wall of the housing and engaged With said strap to support the intermediate portion of the tube bundle.

2. In a heat exchanger wherein a housing encloses a series of long tubes supported in spaced apart tube plates, and each tube has wound thereon a coiled fin, means to support the tubes intermediate said tube plates including a tensionable strap embracing the intermediate portion of the tube assembly and supported by the housing, a series of tube spacers engaging several fin convolutions of each tube and cooperating with said strap in clamping the tube assembly and said spacers being held against axia displacement by end engagement with deformations in the tube fins.

3. In a heat exchanger having a series of finned tubes, flexible means to brace the tubes from one another intermediate their length including a plurality of split spacer sleeves embracing the tube fins, one on each of said tubes, each of said sleeves engagng neighboring sleeves, and a tensionable band encircling the tube assembly and engaging the split sleeves on the outerrnost tubes to crowd the sleeves together and individually into snug fit with the ns embraced thereby.

4. In combination, a group of spaced tubes. a helical coil of wire helically wrapped on each tube and a spacing collar embracing several Wrappings of coiled wire intermediate opposite ends of each tube, said wires adjacent the ends of the several collars having convolutions distorted so as to prcject radially beyond the collar embraced convolutions and thereby restrain axial collar Shift.

5. In combination, an assembly of spaced tubes each having wrapped thereon a coil fin wire and intermediate tube spacer sleeves, each sleeve having an internal diameter such as to fit snugly certain of the coils, said wire immediately next to the sleeve ends being formed so as to project in stop abutment relation with the sleeve ends for sleeve retention against axial Shift.

6. In aheat exchanger having a series of finned tubes, flexible means to brace the tubes from one another intermediate their length comprising, a plurality of contractible spacer sleeves embracing the tube fins, one on each of' said tubes, e'ach of said sleeves engaging neighboring sleeves, and tensionable supporting' means for crowding toetherand contracting' the contractible spacer sleeves'. 4

7. In a heat exchanger' having a series of finned tubes', flexible means to brace the tubes from cne another intermediate their length comprising, a plurality of contractible'spacer sleeves embracing the tube fins, one on each of said'tubes, each of 4 said sleeves engaging neighboring sleeves, retainer formations carried by the tubes for end engagement with the spacer rngs to locate the same against axial displacement, and tensionable supporting means for crowding together and contracting the contractible spacer sleeves.

8. In a heat exchanger, a housing, a bundle of finned tubes within the housing, fiexible interengaging spacers sleeved on the finned tubes intermediate their lertgh, a tensionable band surrounding the tube assembly in the region of said spacer sleeves, a series of circumferentiaily spaced supporting and locating devices carried by the housing and engaged with the band, and means for adjusting said devices radially inwardly.

JOHN RALPH HOLMES. ADOLF SCHWARZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,338,479 Zimmerman Apr. 27, 1910 2,012,920 Sumerfieid Aug. 27, 1935 2,102,723 Kotzebue Dec. 21, 1937 2,146,614 Bergdoll Feb, '7, 1939 2,24L209 Lea May 6, 19 41 2,335,479 Berkeley et al Nov. 30, 1943 2,402209 Ryder June 18, 1946

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