MXPA99003534A - Ignition water heater through compact gas with better combustion chamber - Google Patents

Abstract

The present invention relates to a gas-fired water heater for a recreational vehicle comprising: a tank for receiving and storing water, an internal combustion chamber inside the tank consisting of two horizontal tubes, each of which has a rear end that is mounted in holes in a front head of the tank, and a coupler that joins the tubes at their rear ends so that the chamber forms a "U" shape that allows hot gases from a burner to enter and exit on a front side of the tank and a water heater, means for supplying fuel and ignition to the gas burner, and means for introducing cold water to a lower portion of the tank so that the hot water will leave an upper portion of the tank to supply hot water to various hot water exits inside the recreational vehicle, where the coupler in the combustion chamber is made of a single piece of formed metal or with an aperture cross section having two end arches formed to receive the outer halves of the tubes, the end arches and the tubes have the same radius, and a plate with perforated openings to receive the internal halves of the tubes, the plate it is subsequently welded between the two tubes to form a tube and plate assembly, where the tube and plate assembly is pressed and soldered with the coupler, and where the holes in the front head to receive the combustion chamber tubes They have flat highlights to facilitate the welding of the tubes to the

Description

IGNITION WATER HEATER THROUGH COMPACT GAS WITH IMPROVED COMBUSTION CAMAR-A BACKGROUND OF THE INVENTION This invention relates generally to an improved compact gas fired water heater for installation in recreational vehicles. Specifically, this invention relates to a gas-fired water heater of compact size with an improved combustion chamber that offers manufacturing, dimension, cost and operation advantages over water heaters of this type currently available for such installations. . Although combustion chambers of various designs and configurations have been invented and used for furnaces and other space heating applications, the methods used for years for combustion chambers for water heaters for the recreational vehicle market have been limited to designs Direct venting type gas-fired to meet rigid space limitations, test pressure requirements mandated by various regulatory codes, and design methods that will offer the most economical products to the recreational vehicle manufacturer and the consumer. Accordingly, recreational vehicle water heaters continue to be made with direct venting type combustion chambers using either first inclined tubes disclosed in the Hammersley and Carlson patents, where the inlet and outlet ends of a tube are both placed. on the front side of a water heater, or first a larger diameter straight horizontal tube was suggested in the Wariner patent, closed at the rear, where a burner was placed in the lower front half of the tube below the a mid-division plate with an opening in the back, so that the hot gases circulate from the front to the rear of the tube and then exit on the front side in the upper half of the tube horizontally placed. With the tube-type combustion chambers inclined in many current recreational vehicle water heater tanks, hot gases are injected into the tube through a burner placed at the entrance of a tube in the lower portion of the front of the tube. water heater. Then, hot gases circulate through the tube and exit the tube in an upper portion of the same front side. Since both ends of the tube, the inlet and outlet, are placed on the front of the water heater, the front parts of these water heaters must be large enough to accommodate the "U" shaped tilt in the tube. between the entrance and the exit. Due to the large radius required to make the "U" -shaped tilt without distorting the pipe, the dimensions of such water heaters must be either wider or larger than a water heater using the individual straight pipe type construction . Consequently, water heaters that use inclined "U" shaped tubes will not usually be fixed to the openings or cut sizes desired by many recreational vehicle manufacturers for the installation of water heaters, and can not be used. in the market later as replacements for water heaters employing straight pipe type combustion chambers that have been installed on the side walls of recreational vehicles with smaller cutting dimensions. Since water heaters with individual horizontal pipe type combustion chambers that have been used for years have smaller width or height dimensions on the front of water heaters than water heaters made with combustion chambers of Type of tilt tube, and in this way are fixed to the smaller openings that are desired by the recreational vehicle manufacturers, have certain disadvantages. With this method of construction, a burner placed in the lower portion of the tube, discharges the combustion products through the lower portion of the horizontal tube below an integral middle separator extending approximately four fifths of the way from the front to the rear of the tube. The gases make a turn in the back of the tube as they make contact with the back closure plate, and then move upwards and exit through the upper portion towards the tube above the inlet. One skilled in the art can easily observe that this construction, although it allows the frontal compaction capability, has severe limitations in operation due to the reduction of the movement of the hot gases that results from the back pressure caused by the abrupt turn in the rear part of the tube. In addition, the main concentration of the fiama from the burner in the lower portion of the tube is on the central tube spacer instead of the tube wall. The heat transfer efficiency is further reduced due to the large internal diameter of the tube, generally 11.43 cm, which results in the gases moving more slowly than they do in a tube with a less open area. A smaller tube diameter used in the same way, while accelerating the flow of gases having less internal area, may not be effective at the same time since the total amount of heating surface that makes contact with water may also be reduced consequently, and in general, even water heaters with 11.43 cm diameter pipes have hot surface limitations below that of water heaters that use tilt tubes with separate inlets and outlets. The total hot gas path distance allowed with the straight horizontal tube type construction is also considerably less than the distance traveled within a combustion chamber using separate inlet and outlet tubes, further reducing the transfer efficiency of heat of such water heaters. In a more recent Bridegum patent, a combustion chamber is used for compact water heaters that do not use a tube of any kind. This combustion chamber, similar to those used in furnaces, uses two shell-shaped valves welded together to form an internal flow pattern inside a tank. Although it satisfies the pressure requirements commanded by water heaters, this type of construction has several disadvantages that inhibit its use. Due to the large perimeters of the two halves used in their construction, a considerable amount of increased welding is required to weld the two halves together. In a typical water tank for a water heater of this type, the amount of solder required for the tank is increased by approximately 20 to 25%. In the case of a glass lined tank, the increase in the area of the welded surfaces inside the tank requires that additional cathode protection be provided in the form of a larger anode, thus increasing the cost of the water heater for the user. In addition, to insert the front of this type of combustion chamber into the front head of the water heater tank before welding, a large hole consisting of two circular holes joined together at the center with a narrow hole is required additional. This type of manufacture makes it difficult to perform an automatic welding, since the surfaces where the front head and the combustion chamber come into contact are on different radii. The problems of fixing between the combustion head and the combustion chamber complicate the problem even more, since minor variations in the size of the weld dimensions on the portions of the combustion chamber that must come out through the frontal head of the tank can result in the combustion chamber not being fixed through holes drilled in the head, or there is a loose fastening on the front head which in turn makes it impossible to weld the combustion chamber successfully to the head with automatic welding. Therefore, there is a need for a water heater with a combustion chamber design that allows the water heater to meet the smaller front dimensional requirements for compact water heaters for recreational vehicles, which allow the best savings by reducing the total amount of welding required, which allows a fully automatic welding of the combustion chamber in the head of the front tank, which ensures a long life of the tank in the case of tanks lined with glass without adding an additional anode surface, and which At the same time allow the water heater to have a higher recovery and better efficiency than heaters of this type currently aable to recreational vehicle manufacturers and the after market. The present invention satisfies this need and provides additional related advantages.

COMPENDIUM OF THE INVENTION According to the invention, an improved combustion chamber is provided for compact water heaters fired with gas for recreational vehicles that will allow the water heater to satisfy the minimum size front dimensional requirements for water heaters of this type and that at At the same time they have an increased amount of heating surface and distance of travel for the hot gases that move inside the combustion chamber. Another object of the invention is to allow the water heater to obtain a BTU inlet and larger amounts of hot water than similar water heaters currently available with comparable front dimensions. A further object of the invention is to allow the water heater to operate at higher efficiencies, while at the same time allowing smaller front dimensions. Still another object of the invention is to provide an improved combustion chamber with more moderate surface areas that are more suitable for glass coating when used with steel tanks. Yet another object of the invention is to provide an improved design that will pass the controlled hydrostatic test pressures of 21.09 kg / cm2 without increasing the thickness of the material used in manufacturing.

A further object of the invention is to provide a design that will allow all welds to be made automatically on flat surfaces while minimizing the cost of welding equipment, while at the same time securing a better quality weld. A further object of the invention is to reduce the total amount of welding surface, and the time and the welding material, required in the manufacture of a combustion chamber for use in a water heater tank with similar frontal dimensions. The novel aspects that are believed to be characteristic of the invention, both the design and the method of use, together with other objects and advantages will be better understood from the following description, considered together with the accompanying drawings in which the preferred embodiments of the invention are illustrated by way of example. However, it is expressly understood that the drawings are for the purpose of illustration and description only, and are not intended to be taken as a definition of the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate the invention. In which: Figure 1 is a cross-sectional perspective view of a small compact water heater tank with the combustion chamber using the preferred embodiment for a gas-fired water heater for recreational vehicles. Figure 2 is a perspective cross-sectional view of a complete small compact water heater using the preferred embodiment. Figure 3 is a top view of a flat center plate perforated with since it is placed between and welded to two horizontal tubes in the preferred embodiment. Figure 3A is a top view of a perforated flat plate with die for an alternative embodiment. Figure 4 is a side cross-sectional view of the coupler used in the preferred embodiment. Figure 4A is a top view of the coupler used in the preferred embodiment. Figure 4B is a front end view of the coupler used in the preferred embodiment. Figure 5 is a side cross-sectional view of the subassembly with the two horizontal tubes and the center plate that attaches to the coupler. Figure 5A is a front end view of the assembled center plate and the two horizontal tubes. Figure 6 is a side cross-sectional view of the coupler, center plate and tube assembly. Figure 6A is a central view of the coupler, center plate and tube assembly.

Figure 7 is a front cross-sectional view of the front head of the water heater tank showing the closeness between the upper and lower openings for welding to the tubes. Figure 7A is a side cross-sectional view of a front head showing flat raised surfaces where the tubes will be welded to the head. Figure 8 is a side cross-sectional view of a water heater tank using the preferred embodiment, showing the combustion chamber positioned and welded in the tank.

DETAILED DESCRIPTION OF THE INVENTION As shown in Illustrative Figure 1, a water heater tank is provided which is constructed with the following basic parts: mainly a front head 1, a rear head 2, a tank sheet 3, a coupling for a relief valve temperature and pressure 4, a thermostat coupling 5, a drainage coupling 6, a cold water inlet coupling 7, a hot water outlet coupling 8, a combustion chamber 11, a combustion chamber inlet opening 9 and a combustion chamber outlet opening 10. The tank shown in Figure 1 is manufactured in a small compact water heater, Figure 2, with a cover 22, covering the insulation surrounding the tank 12, and a control housing 13, with a door 14, enclosing the various components on the front of the water heater. In the preferred embodiment, a burner 15 is placed in the lower inlet of the combustion chamber 9 to receive gas from a thermostat / gas valve combination 16 through the manifold 17. The gas to the burner 15, is driven by a pilot 18, together with a thermocouple, or in other models an ignition module by electrode and spark together with a gas valve and thermostat. Once the ignition is established, the water in the tank surrounding the combustion chamber is rapidly heated as the hot gases flow rapidly from the burner at the inlet of the combustion chamber 9, making an upward turn on the radius moderation of the coupler in the rear of the chamber 11, before leaving in the combustion chamber outlet 10. As a rule, an appropriate thermal protection 19 is also located within the control housing together with a drainage 20 to protect against winter climates to the water heater, and a temperature and pressure relief valve 21. A cold water inlet 7 and a hot water outlet 8 are provided on top of the water heater, together with an attachment for an anode not shown, if tanks are used covered with steel-glass. Importantly, the single combustion chamber 11 provides a maximum number of square centimeters of heating surface, approximately 25% or more of the surface than water heaters of this type currently available with similar front dimensions of 31.75 cm or less. in height as in width. At the same time, the passage area is small enough, typically 12% smaller than a combustion chamber made with a single horizontal straight tube, to allow the gases to move more quickly and thereby increase the transfer efficiency of hot. The novel design of the coupler in Figure 4 ensures that gases will flow moderately through the rotation in the back of the combustion chamber increasing efficiency and recovery. The coupler in Figure 4 is formed quickly and economically, preferably on a punch press, through individual stamping, to the exact tolerances with the spokes on the two ends being identical to the tube spokes being used. Two tubes of the correct length and the same radius as the ends of the coupler are placed against and welded to the center plate, Figure 3, from the rear side. Importantly, the tubes are placed against the center plate so that only a small portion of the tubes, typically 0.635 cm, extends beyond the plate, providing a suitable clearance to perform the operation automatically with a circumferential type welder . The subassembly, Figure 5, comprising the tubes and the center plate, is then inserted and welded to the coupler, Figure 4. A person skilled in the art will readily observe that this subassembly can be compressed into the coupler with an airtight fit., where the unique design allows a final automatic weld around the oval perimeter to complete the assembly. The finished assembly, Figures 6 and 6A, is then attached to the front tank head by inserting the front parts of the two tubes through the perforated and raised apertures provided in the front head, Figures 7 and 7A. The flat overlaps on the front head, Figure 7A, allow the two final welds in the tubes to the front head, which will then be welded quickly and economically with an automatic circumferential type weld. The front head is then inserted and welded into the finished tank, Figure 8, in a customary manner. In an alternative embodiment, Figure 3A, an oval plate is perforated with a die with two holes to receive the two horizontal tubes. The two tubes are then inserted into the holes in the plate and welded to the plate from the back side, where adequate space is provided to also allow an automatic circumferential weld. The plate is then supported against the coupler, where an individual automatic oval weld completes the assembly automatically. The two tubes of the complete assembly are then inserted into the two holes in the front head and automatically welded just as in the preferred embodiment. In addition, the entire assembly, either in the preferred or alternative embodiment, requires considerably less welding time and less welding material than a combustion chamber made with the technology disclosed in the previous Bridegum patent, which employs the two halves with form of shell In addition, the invention provides a considerably hotter surface, and a subsequent increase in recovery of up to 40% more for a small compact water heater, than that provided by a combustion chamber employing a single horizontal pipe using the suggested construction in the Wariner patent, while at the same time allowing the finished water heater to maintain front dimensions smaller than the water heater using the inclined tube construction disclosed in the Carlson or Hammersley patents. The above detailed description is illustrative of the embodiments of the invention and it should be understood that the additional modalities will be obvious to those skilled in the art. These additional embodiments are considered within the scope of the invention.

Claims (5)

1. - A gas-fired water heater for a recreational vehicle or other installations mounted on side walls, comprising a tank for receiving and storing water, an internal combustion chamber within the tank consisting of two horizontal tubes mounted on the front head of the vehicle. tank, joined at the rear by a coupler, so that the tubes form a pattern configured as "U" allowing hot gases from a burner to enter and exit on the front side of the tank and water heater, means to supply fuel and ignition to the gas burner placed inside the lower tube of the U-shaped combustion chamber of said tank, and means for introducing cold water into the lower portion of the tank, so that the hot water will come out in the upper portion of the tank to supply the hot water to several hot water exits inside the recreational vehicle or other installations that require heaters of water fired with gas mounted on the side wall.

2. The water heater according to claim 1, wherein the coupler in the combustion chamber is made from a single piece of metal formed with two end radii formed to receive the outer halves of tubes using the same spokes and a perforated plate with spokes to coincide with the internal halves of the tubes, subsequently welded between the two tubes, wherein the tube and full plate assembly is then compressed and welded to the coupler.

3. The water heater according to claim 1, wherein the coupler in the combustion chamber is made from a single piece of suitable metal with the two end radii formed to receive the outer halves of the tubes using the same radii, and a single larger plate than the front of the coupler is drilled with two holes with the same radius as the end radii of the coupler, where two tubes are inserted and welded into the plate, and said plate and tube assembly then it is placed against and welded to the coupler with the tubes coinciding or fixing on the two extreme spokes of the coupler.

4. The water heater according to claim 2, wherein the holes on the front head to receive the combustion chamber tubes have flat highlights to facilitate welding of the pipes to the head.

5. The water heater according to claim 3, wherein the holes on the front heads for receiving the combustion chamber tubes have flat enhancements to facilitate welding of the tubes to the front head.