US 3788395 A
A cover assembly is used for retaining members such as the heat exchanger elements of a heat exchanger in clamping engagement with a diaphragm which is interposed therebetween. The cover assembly has an inner plate and an outer plate which form a chamber within which a fluid medium is contained. The fluid is pressurized to provide force distributed uniformly over the surface of the inner plate, thereby enabling this plate to resist forces which would otherwise tend to cause it to buckle, and assuring clamping pressure to clamp the members together over their entire contact area to enable good thermal transfer therebetween.
Claims available in
Description (OCR text may contain errors)
Knoss et al.
[ Jan, 29, 1974 FLUID PRESSURIZED COVER DEVICE I nventors :te llan Kn00s, M alib u, Calif; Soren F; SIYjiiEgdhl, Taby; Bertil Ingemar Bostrom, Danderyd, both of Sweden AGA Aktiebolag, Taby, Sweden; a part interest Filed: Feb. 5, 1973 Appl. No.: 329,539
Related US. Application Data Continuation-impart of Ser. No. 259,009, June 2, 1972.
US. Cl. 165/169, 285/95 Int. Cl F28f 3/12 Field of Search 165/164, 167-170,
Halby et al. 285/95 X Jones 165/157 X Primary Examiner-Charles J. Myhre Assistant ExqminerTheophil W. Streule, Jr. Attorney, Agent, or Firm-Edward A. Sokolski et a1.
 ABSTRACT A cover assembly is used for retaining members such as the heat exchanger elements of a heat exchanger in clamping engagement with a diaphragm which is interposed therebetween. The cover assembly has an inner plate and an outer plate which form a chamber within which a fluid medium is contained. The fluid is pressurized to provide force distributed uniformly over the surface of the inner plate, thereby enabling this plate to resist forces which would otherwise tend to cause it to buckle, and assuring clamping pressure to clamp the members together over their entire contact area to enable good thermal transfer therebetween.
6 Claims, 4 Drawing Figures PATENTEUJMZQ lam 3788395 sum 1 [IF 2 FIG.3
FLUID PRESSURIZED COVER DEVICE This application is a continuation in part of our application Ser. No. 259,009, filed June 2, 1972.
This invention relates to a fluid pressurized cover device and more particularly to such device for use in applying clamping pressure to hold two or more members in clamping engagement with each other.
In our application Ser. No. 259,009, filed June 2, 1972, of which the present application is a continuation in part, a heat exchanger device is described utilizing pairs of heat exchanger elements maintained in thermal contact by mechanically clamping them together between a pair of end plates. In utilizing this type of device with fluids under high working pressures, or in situations where the exchanger elements have large diameters, difficulties may be experienced in maintaining high contact pressure to assure adequate thermal contact, particularly towards the central portions of the heat exchanger elements where it usually is not feasible to place bolts and the rigidity of the end plates must be depended upon to provide the clamping force. Thus, even where rather thick end plates are utilized, there is a tendency for the plates to buckle towards the central portions thereof with a consequent reduction in thermal contact. The device of this invention overcomes this problem by utilizing a cover plate assembly which comprises an inner end plate and an outer end plate which form a chamber into which a fluid medium is placed, this fluid then being pressurized to provide a substantially uniform force over the entire surface area of the inner plate.
lt is therefore an object of this invention to provide a cover device utilizing hydraulic pressurization to provide uniform force over the cover surface area.
It is another object of this invention to facilitate the attainment of good thermal contact between heat exchanger elements.
Other objects of this invention will become apparent as the description proceeds in connection with the accompanying drawings, of which:
FIG. 1 is an elevational view in cross section of a first embodiment of the invention;
FIG. 2 is a cross-sectional view taken along the plane indicated by 22 in FIG 1;
FIG. 3 is an elevational cross-sectional view of a second embodiment of the invention; and
FIG. 4 is an elevational view in cross section of a third embodiment of the invention.
Briefly described, the device of the invention comprises a cover plate assembly having an inner end plate and an outer end plate which form a chamber. This chamber is filled with a fluid which is pressurized to provide a desired pressure over the surface of the inner plate. Such pressurization may be achieved by means of a piston responsive to the fluid pressure of the very same fluid medium of a heat exchanger with which the cover plate assembly is utilized, or by a separate fluid circuit, or may comprise a manually adjusted pressurizing piston. The cover plate assembly is bolted along its edges to the heat exchanger assembly or other device with which it is utilized, mechanical holding pressure being provided along such edges while the fluid pressure is applied over the surface of the inner end plate.
Referring now to FIG. 1, one embodiment of the invention is illustrated as incorporated into a fluid-fluid heat exchanger of the type described in our aforementioned patent application Ser. No. 259,009. Cover plate assembly 11 is used in conjunction with a similar assembly 12 to clamp heat exchanger elements 15 and 16 together in sealed relationship against diaphragm 17. Bolts 35 are used to draw assemblies 11 and 12 towards each other in the same general manner as in the embodiment of FIGS. 7 and 8 of our aforementioned patent application Ser. No. 259,009. As described in said aforementioned patent application, working fluid for the heat exchanger is here distributed to the exchanger elements by means of distributor channels 20.
Cover assembly 11 and identical cover assembly 12 each comprise an inner plate 25 which abuts against the upper surface of heat exchanger element 15 except where channels 20 and 21 are formed therein, and an outer end plate 27 which may be dome shaped and which is attached to the inner plate along its periphery in fluid-tight relationship. A chamber 29 is thus formed between plates 25 and 27. A piston assembly 30 is mounted in end plate 27 to provide pressurization for the fluid 32 contained within chamber 29. Fluid 32 may preferably comprise a nearly incompressible fluid such as oil, water, glycerin, or a liquid metal such as mercury, depending upon the particular application and operating temperature range for the heat exchanger. It is also possible to use near-solid materials having plastic fluid characteristics of very slow equilibrium pressurization, as well as a gas such as air. Cover assembly 1 1 is bolted to cover assembly 12 by means of bolts 35, the heat exchanger elements 15 and 16 thus being sandwiched between the cover assemblies. Piston assembly 30 is acted upon by the working fluid 42 which is fed to this assembly through channel 43. Thus, the fluid 32 is pressurized in accordance with the pressure of the working fluid to provide force over the entire surface of cover plate 25 which will resist buckling under the force of the working fluid pressure. Clamping pressure is also assured over the entire surface of plate 25 so as to hold heat exchanger elements 15 and 16 in adequate thermal contact against the surface of diaphragm 17 along the entire oppositely positioned surface areas thereof. Piston assembly 30 provides pressure amplification greater than unity by virtue of a wider diameter piston element 33 acted upon by the working fluid pressure and a smaller diameter piston 34 connected to piston 33 which operates to pressurize the fluid 32.
Referring now to FIG. 3, another embodiment of the invention is illustrated. This embodiment has the same basic structure and operates in the same manner as the embodiment just described, except for the pressurizing piston assembly 30. In this instance, rather than utilizing a pressure-amplification and feedback system whereby the piston pressure is responsive to the pressure of the working fluid, the piston pressure rather is manually adjustable. Thus, the piston assembly comprises a single piston element 47, the position of which is adjusted by means of handle 50 which threadably engages the top wall of the assembly.
Referring now to FIG. 4, still another embodiment of the invention is illustrated. This embodiment is the same as that of FIG. 1 except for the fact that end plate 27 in this instance has a rectangular cross section rather than being dome shaped, as for the previous embodiment.
It is to be noted that it is possible to obtain the desired pressurization of the fluid 32 by means other than shown in the illustrative embodiments such as by heating this fluid. In such an implementation, the fluid could be placed into chamber 29 at room temperature. 7
the temperature of the fluid would be then raised by the heat generated in the heat exchanger or an external heat source, thereby causing expansion of such fluid and pressurization of the chamber to a suitable level.
The device of the invention thus provides simple yet highly effective means for providing a cover device having uniform contact pressure along its entire surface so as to afford uniform clamping engagement between members such as heat exchanger elements clamped together by such plate.
While the invention has been described and illustrated in detail, it is to be clearly understood that this is intended by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of this invention being limited only by the terms of the following claims.
1. In a heat exchanger having at least one heat exchanger element with a fluid medium being flowed through said heat exchanger element, the improvement comprising a cover device for said exchanger element having a surfaceabutting against said heat exchanger element to apply substantially uniformly distributed pressure thereagainst, said cover device comprising:
an inner plate member forming the surface abutting against said heat exchanger element,
an outer plate member joined to said inner plate member to form a fluid-tight chamber,
a fluid contained in said chamber, and
means for pressurizing the fluid in said chamber, thereby providing substantially uniform pressure against said inner plate member.
2. The device of claim 1 wherein there are a pair of heat exchanger elements and a pair of said cover devices and bolt means for clamping said elements together between said pair of cover devices, said bolt means extending through the edges of said cover devices to draw said cover devices towards each other with the heat exchanger elements sandwiched therebetween.
3. The device of claim 1 wherein said outer plate member is dome shaped.
4. The device of claim 1 wherein said outer plate member has a rectangular cross section.
5. The device of claim 1 wherein the means for pressurizing the fluid comprises a pressure amplifying piston assembly having a piston for applying force to said fluid and means for coupling the fluid medium of said heat exchanger element to one side of said piston pressure amplifying assembly to provide a drive therefor.
6. The device of claim 1 wherein the means for pressurizing the fluid comprises a piston assembly having a piston for applying force to the fluid and means for manually adjusting the piston to set the force applied to the fluid thereby.