SYSTEM AND METHOD FOR ATTACHING STAINLESS STEEL SIDE PLATES TO THE COPPER/BRASS TUBES OF A HEAT EXCHANGER CORE

Abstract

A system and method for attaching very thin stainless steel plates to a radiator or heat exchanger core using the CuproBraze® brazing technique. The use of thin stainless steel side plates produces the structural strength needed in the radiator or heat exchanger core assembly without adding an excessive amount of weight. Heretofore, the CuproBraze® brazing technique has not been used with stainless steel. The stainless steel radiator or heat exchanger core side plates need only be about half as thick as a copper/brass side plate to provide the strength needed for support of the radiator or heat exchanger core.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of the filing date of U.S. Provisional Application No. 61/351,727, filed on Jun. 4, 2010.

STATEMENT REGARDING FEDERALLY FUNDED RESEARCH AND DEVELOPMENT

The invention described in this patent application was not the subject of federally sponsored research or development.

FIELD

The present invention pertains generally to a process of increasing the mounting strength of heat exchanger cores using the CuproBraze® brazing technique by mounting stainless steel side plates to the core. The present invention more particularly pertains to increasing the structural strength of radiator or heat exchanger cores by mounting stainless steel side plates to the radiator or heat exchanger core using the CuproBraze® soldering technique in a way in which the Cuprobraze® soldering technique has not previously been used.

BACKGROUND

Radiator and heat exchanger cores are made from copper and brass because copper and brass possess the ability to transfer more heat per core size than any other materials. The thermal efficiency of cores made from copper and brass results in smaller sized cores that remove the thermal energy from the cooling fluid that is typically used to control the operating temperature of large engines or other heat producers. Copper and brass heat exchangers can operate at temperatures well above 250° C. whereas cores made from other materials such as aluminum are severely compromised where the cooling fluid temperature passing through the core is at above 200° C. Therefore, cores made from copper and brass are found in most radiators and heat exchanger assemblies.

The International Copper Association has specifically developed a brazing/soldering process for the manufacture of heavy-duty mobile and industrial copper and brass radiators and heat exchangers. This process is commonly known by those skilled in the art by its trademarked name, CuproBraze®. However, if conventional copper and brass materials are used to provide a structure for a radiator or heat exchanger made using the CuproBraze® brazing technique to then obtaining the required structural support for the heat exchanger core an requires that an excessive amount of weight be added to the radiator or heat exchanger core to provide the needed structural support. Added weight is particularly objectionable if the radiator is used on a racing vehicle as race vehicle builders are continually looking for ways to reduce the weight of a racing vehicle. In addition, added weight significantly adds to the cost of radiator or heat exchanger core assemblies manufactured using the CuproBraze® soldering technique.

Accordingly, a need remains in the art for a process of attaching a support structure to a radiator or heat exchanger core made using the CuproBraze® soldering technique, which support structure provides the required structural strength and can be attached to the radiator or heat exchanger core using the CuproBraze® soldering technique.

SUMMARY

The system and method of the present invention describes the steps for attaching thin stainless steel plates to the heat exchanger core using the CuproBraze® soldering technique and the radiator or heat exchanger core assembly made when the disclosed steps are followed.

The use of thin stainless steel side plates produces the structural strength needed for a core used in a radiator or heat exchanger without adding an excessive amount of weight. Heretofore, the CuproBraze® soldering technique has not been used with stainless steel. The reduction in weight of a radiator or heat exchanger core assembly manufactured by the disclosed system and method occurs because stainless steel radiator side plates need only be about half as thick as a copper/brass side plate would need to be to provide the strength needed for support of the core portion of the radiator or heat exchanger assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the of the present invention may be had by reference to the drawing figures wherein:

FIG. 1 is a simplified view of a radiator or heat exchanger core showing the position of the stainless steel plates in relation to other elements of the radiator or heat exchanger core;

FIG. 2 is a simplified view of a radiator or heat exchanger core assembly from a different perspective showing the position of the stainless steel plates in relation to other elements of the radiator core as well as showing the location of the top and bottom header plates which are attached to the radiator or heat exchanger core assembly; and

FIG. 3 is a flowchart of the process steps of the system and method of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Reference is made to FIGS. 1 and 2 for a description location of the components a typical radiator or heat exchanger core assembly 10. The stainless steel side plates 14 are attached to each side of the core portion 12 of the radiator or heat exchanger core assembly 10. Alternatively stainless steel bracketry 25, and/or componentry for mounting of the radiator or heat exchanger core assembly 10 may be used in addition to or in place of the stainless steel side plates 14. A bracket may be a stainless steel girdle which may be used for support. The radiator or heat exchanger core 12 is made up of a plurality of fin plates 18 which are mounted between coolant tubes 16 as is well known in the art.

FIG. 2 shows the location of the top header 20 and the location of the bottom header 21 on either side of the heat exchanger core assembly 10. The actual locations and number of fin plates 18 and coolant tubes 16 may vary depending on the amount of fluid cooling required.

FIG. 3 is a generalized flowchart showing the basic process steps associated with the use of the process of manufacture of a radiator or heat exchanger core assembly 10.

As shown in FIG. 3, the first step 101 in the disclosed process is applying a light and even coat of a commercially available CuproBraze® paste or its equivalent ribbon or film on one side of the stainless steel side plates 14 and both sides of the coolant tubes 16. The CuproBraze® paste is then dried 102 using a variety of different ways known to persons having ordinary skill in the art. In the preferred embodiment the CuproBraze® paste is dried at approximately 120° C. for 5 minutes. The coolant tubes 16, fin plates 18, and stainless steel side plates 14 are then assembled 103 in a press with the coated sides of the stainless steel side plates 14 in physical contact with the fin plates 18. This assembly is held together with a clamp which is placed in a position to hold the stainless steel side plates 14 to the radiator or heat exchanger core 12.

After removing the radiator or heat exchanger core assembly 10 with the stainless steel side plates 14 attached thereto from the press, the top header 20 and bottom header 21 are then pressed 104 on the ends of the coolant tubes 16 and a coat of the CuproBraze® paste or its equivalent ribbon or film is applying 105 on to the header/tube joints. This combination of radiator or heat exchanger core 12 with stainless steel side plates 14 affixed thereto and the top and bottom headers 20 and 21 is then placed into an oven constructed to enable use of the CuproBraze® brazing technique. Once in the oven, the clamped together parts are run through a heating cycle 106 as is known in the art. The heating cycle includes an approximately a 5 minute±1 minute purge, a rapid warm-up to approximately 1243° F.±10° F., a 60 second±30 second soak time at approximately 1243° F.±10° F., followed by a cool down to approximately room temperature to 200° F.

The radiator or heat exchanger core assembly 10 with the top and bottom headers 20, 21 affixed thereto is then removed from the oven constructed to enable the CuproBraze® brazing technique. The clamp is removed and the radiator or heat exchanger core assembly 10 with the top and bottom headers 20, 21 attached is first inspected and then pressure tested for leaks.

OTHER USES FOR STAINLESS STEEL WITH A RADIATOR OR HEAT EXCHANGER CORE

In addition to the above described preferred embodiment of the system and method of the present invention, the system and method of the present invention may be used to fabricate radiators or heat exchangers for special uses. Among these special uses are the following situations:

1. In situations where heat is to be extracted from highly corrosive fluids by use of the disclosed process—a heat exchanger using the process of the present invention can be built with stainless steel tubes/headers/tanks while still using the high efficiency copper fins.

2. For show applications wherein a stainless steel/copper radiator and/or transmission fluid coolers can be built using the process of the present invention and then polished to a high luster.

3. For extremely harsh conditions, such as off-road racing or heavy construction equipment wheeled or tracked, a radiator assembly can be made using the disclosed process with stainless steel tubes/headers/tanks using the process of the present invention would be able to stand more abuse without leaking.

In all respects, it should also be understood that the drawings and detailed description herein are to be regarded in an illustrative rather than in a restrictive manner, and are not intended to limit the system and method of the present invention to the example disclosed. Rather, the system and method of the present invention includes all processes within the scope and spirit of the invention as claimed, as the claims may be amended, replaced or otherwise modified during the course of related prosecution. Any current, amended, or added claims should be interpreted to embrace all further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments that may be evident to those of skill in the art, whether now known or later discovered. In any case, all substantially equivalent processes should be considered within the scope of the disclosed invention and, absent express indication otherwise, all structural or functional equivalents are anticipated to remain within the spirit and scope of the disclosed system and method.

Claims

1) A process for attaching stainless steel side plates to the copper/brass tubes and fins of a radiator or heat exchanger core, said process comprising the steps of:

i) applying a light even coat of a CuproBraze® paste or its equivalent ribbon or film to one side of said stainless steel side plates and drying at approximately 120° C. for 5 minutes;

ii) applying a light even coat of a CuproBraze paste or its equivalent ribbon or film to both sides of said copper/brass tubes of said radiator or heat exchanger core and drying at approximately 120° C. for 5 minutes;

iii) assembling said copper/brass tubes and fins of said radiator or heat exchanger core in a press placing the coated sides of said stainless steel side plates against the coated sides of said radiator or heat exchanger core and compressing together;

iv) placing headers on the end of said copper/brass tubes

v) applying CuproBraze paste or its equivalent ribbon or film on the joints between said headers and said copper/brass tubes

vi) heating in an oven according to the following cycle:

(1) a purge of about five minutes±one minute;

(2) a rapid warm up to about 1243° F.±10° F.;

(3) an about 60 second±30 second heat soak at about 1243° F.±10° F.;

(4) a cool/down to approximately room temperature to 200° F.

2) A radiator or heat exchanger core assembly made according to the steps of claim 1.