1. Field of the Present Invention
The present invention relates generally to systems for heating automotive fluids, and, in particular, to systems, methods, and electrically-heated tubular assemblies for transferring heat to a fluid flowing therethrough.
2. Background
Because automobiles, trucks, and a wide variety of other motor vehicles are often used in low-temperature environments, their subsystems and components must be able to operate under conditions ranging from warm to extremely cold. In particular, automotive subsystems and components that make use of fluids, including wiper fluid systems, cooling systems, fuel lines, and the like, must be capable of reliable operation in such conditions. One primary problem faced by such systems is that of keeping the fluids flowing therethrough from congealing, freezing or the like. Thus, an ongoing need exists for heating systems, using inexpensive, lightweight and non-bulky materials for quickly and efficiently heating or warming fluids in such automotive systems.
Raising the temperature of at least some automotive fluids may have other benefits as well. For example, a fluid such as wiper fluid may be comprised of water and detergent, along with a substance to lower the freezing temperature of the composition, such as an alcohol, e.g., methanol or isopropyl, and/or ethylene glycol. Higher temperatures may help ensure that such fluids are more thoroughly mixed; this may be particular critical for fluids such as wiper fluid in which the anti-freezing substance (which typically has a significantly lower boiling point than water, e.g., methanol) must be prevented from being superheated into the evaporation state and forced out of the mixture. Further, automotive studies have shown that the cleaning action of wiper fluid is increased as much as 2000% when the alcohol temperature is elevated to just under its boiling point. Also, the heating of a wiper fluid additionally provides a de-icing feature, which may be of equal or greater importance to consumers.
The present invention accordingly provides a system and method for delivering a heated fluid, particularly adapted for use in fluid delivery systems and methods employed in automotive vehicles. The present invention further provides a tubular assembly for heating fluids, particularly automotive fluids, and especially adapted for use in such systems and methods.
Broadly defined, the present invention according to one aspect is a tube heating assembly, including: a heating tube having approximate and a distal end portion; a manifold insert having a proximate and a distal end portion and being disposed concentrically within the heating tube; and a pair of end caps removably secured to the proximate and distal end portions of the manifold insert and the heating tube respectively. In a feature of this aspect, the manifold insert may include a means for creating turbulence in the fluid, e.g., via a raised spiral thread on the surface of the manifold insert.
The present invention according to another aspect is a tube heating assembly, including: a tube; an electrical assembly that heats the tube; and a manifold insert disposed concentrically within the tube. In features of this aspect, the electrical assembly is a resistive path applied to the outside of the tube; and the tube and manifold insert have proximate and distal end portions and further comprising a pair of end caps removably secured to the proximate and distal end portions of the manifold insert and the tube respectively.
In one contemplated embodiment, the tube heating assembly is installed in an automotive vehicle having a fluid delivery system, wherein the tube heating system is adapted for heating a fluid conveyed in the fluid delivery system. In such an embodiment, the tube heating assembly may comprise a heating tube having a proximate and a distal end portion; a manifold insert having a proximate and a distal end portion and being disposed concentrically within the heating tube; a pair of end caps removably secured to the proximate and distal end portions of the manifold insert and the heating tube respectively, the end caps being connected respectively with inlet and outlet sections of the fluid delivery system; and an electrical assembly that heats the tube.
The present invention according to another aspect is a system for delivering a heated fluid, basically comprising a fluid supply, a fluid delivery path comprising a heat exchanger, and an arrangement for pumping fluid in pulses from the fluid supply through the fluid delivery path. The heat exchanger may, for example, be a tube heating assembly of a type as described above. The system preferably is embodied in combination with an automotive vehicle having at least one fluid flow system in which an automotive fluid is conveyed. In such an embodiment, the pumping arrangement may comprise a pump motor and a pulse interface for cycling the pump motor between energized and non-energized states or, alternatively, may comprise a valve in the delivery path and a device for cycling the valve between opened and closed states.
The present invention according to another aspect is a method for delivering a heated fluid, basically comprising the steps of providing a fluid supply, and delivering a fluid in pulses from the fluid supply along a delivery path including a heat exchanger, which may for example be a tube heating assembly of a type as described above. The method preferably is carried out in an automotive vehicle having at least one fluid flow system in which an automotive fluid is conveyed. In such an embodiment, the pulsation of the fluid may be performed by cycling a fluid pump motor between energized and non-energized states or, alternatively, by cycling a valve in the fluid delivery path between opened and closed states.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Further features, embodiments, and advantages of the present invention will become apparent from the following detailed description with reference to the drawings, wherein:
Referring now to the drawings, in which like numerals represent like components throughout the several views, the preferred embodiments of the present invention are next described. The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
In operation, the heating tube assembly 10 operates as follows. Windshield wiper fluid enters one end cap 16 and flows through the concentric bore 34 of the T-shaped flow path 32 within the end cap 16. Then the fluid is directed to the outside edges of the of end cap 16 by the cross-bore 36 of the T-shaped flow path 32. The fluid then exits the end cap 16 via the openings 38 at the ends of the cross-bore 36 of the T-shaped flow path 32. The end cap openings 38 direct fluid flow to an outer flow path located between the outside surface of the manifold insert 14 and the inside surface of the heating tube 12.
The fluid flows through the outer flow path for the extent of the length of the manifold insert 14 and heating tube 12. It then exits through the end cap 16 at the other end of the tube heating assembly 10 by passing through the openings 38 and into the cross-bore 36 and from there through the central concentric bore 34 and out into the fluid line or pipe (not shown) connected thereto.
As the fluid flows through the tube heating assembly 10, it is heated by the heating tube 12. In fact, the tube heating assembly 10 of the present invention provides improved heat transfer capabilities as compared to conventional tube heating assemblies. The present invention provides reduced fluid volume, increased fluid velocity, increased turbulent flow and increased heating area. More specifically, the flow path available within the tube heating assembly 10 is limited in volume because the manifold insert 14 displaces most of the volume within the heating tube 12. Because the volume available for the fluid flow is limited, the fluid velocity increases as the fluid enters the outer flow path. Increased fluid velocity aids in improving heat transfer of the tube heating assembly. Additionally, the reduced fluid volume within the tube heating assembly requires less power to raise the fluid temperature than conventional heating assemblies. The spiral threading 20 of the manifold insert 14 creates a spiraled path for fluid flow and increases the turbulence of the fluid flow through the tube heating assembly 10. The turbulent flow forces more fluid to contact the surface of the heating tube 12 thus heating the fluid more quickly. Turbulent flow also causes the fluid to mix more thoroughly, which is particularly beneficial for a fluid mixture comprising multiple fluid types, e.g., windshield wiper fluid. The tube heating assembly 10 of the present invention increases the heating area of the heating tube 12 by using a heating tube 12 with an outer diameter larger than that of a conventional heating tube; however, the actual fluid volume within the tube heating assembly 10 is reduced because of the presence of the manifold insert 14 disposed within the tube heating assembly 10.
Because of the improved heat transfer rate of the tube heating assembly 10 of the present invention, the tube heating assembly 10 is capable of providing heated fluid on demand, i.e., no heat is required until fluid flow begins. However, the tube heating assembly 10 may also be operated to maintain fluid at an elevated temperature. It is contemplated that the heating assembly 10 may be equipped additionally with a thermal feedback arrangement, e.g., SMD thermistors, attached directly to the outer surface of the heating tube 12, to provide feedback to a control system associated with the assembly. It is also contemplated to provide a means for heat transfer from heat generating control elements which may be associated with the assembly, e.g., field transistors, so as to further improve the heating efficiency of the heating assembly.
An additional improvement of the present invention is the end cap design that allows for air to be released from the manifold insert 14 during high pressure events such as fluid freezing or boiling. The manifold insert 14 can absorb pressure from frozen fluid or boiling fluid and release the pressure though the air outlets 46 in the end caps 16.
The tube heating assembly 10 is electrically connected in the electrical system of the automobile to heat the washer fluid as it is delivered by the pump 54 through the manifold in the heater assembly 10. The tube heating assembly 10 is connected in the ignition circuit of the automobile between the ignition switch assembly 60 and the alternator or other source of operating voltage energized when the automobile engine is in operation (indicated only symbolically at OV) to provide power to the heating assembly 10 only when the ignition switch is in the closed position with the automobile engine in operation. The tube heating assembly 10 is connected, directly or indirectly, to the positive and negative terminals of the ignition battery 58 of the automobile electrical system to provide direct current electrical voltage to the heating assembly 10 when the ignition circuit is closed during engine operation. A disabling switch sub-circuit 62 is connected in the ignition circuit and to the tube heating assembly 10. The disabling sub-circuit 62 is normally closed during ongoing normal operation of the automobile electrical system, but is configured to open if the total operating amperage draw on the system reaches a level which endangers the minimum voltage required to supply electrical operating current to the critical systems of the automobile engine, e.g., to insure correct firing of the engine spark plugs. As depicted in
As is conventional, the windshield washer fluid delivery system is provided with a warning circuit 64 to monitor the fluid level in the reservoir 50 and to generate a warning signal, e.g., via an illuminated warning lamp, in the event the quantity of fluid in the reservoir falls below a predetermined minimum level. The tube heating assembly 10 is also connected in the warning circuit 64 to deactivate operation of the tube heating assembly 10 in the event there is insufficient fluid in the reservoir for normal operation of the fluid delivery system.
As is also conventional, the operating motor 56 to the fluid pump 54 is also connected in the ignition circuit of the automobile between the ignition switch assembly 10 and the operating voltage source OV and includes a manually operated switch 66 for selectively actuating and deactuating the windshield washer fluid delivery system when desired. The switch 66 is also shown in its normally open deactuated position.
The operation of the tube heating assembly 10 in conjunction with the windshield washer fluid delivery system of
The advantages of the provision of the fluid heating capabilities of the present invention will be understood with reference to the graphs of
Based on the foregoing information, it is readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those specifically described herein, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing descriptions thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for the purpose of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended to be construed to limit the present invention or otherwise exclude any such other embodiments, adaptations, variations, modifications or equivalent arrangements; the present invention being limited only by the claims appended hereto and the equivalents thereof. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for the purpose of limitation.
This application is entitled to the benefit of, and claims priority to provisional U.S. Provisional Patent Application Ser. No. 60/654,701, filed Feb. 21, 2005, and entitled “System for Heating Automotive Fluids” the entirety of which is incorporated herein by reference.
Number | Date | Country | |
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60654701 | Feb 2005 | US |