DIESEL FUEL TEMPERATURE CONTROLLING METHOD AND APPARATUS

Abstract: A method and apparatus for raising and stabilizing the temperature of diesel fuel to the optimum combustion temperature using a highly efficient plate type heat exchanger (3). The invention utilizes a mechanically actuated flow control valve (5) to regulate the engine coolant flow to maintain and stabilize the fuel temperature in the optimum range regardless of the make of engine or ambient temperature conditions. This allows the heat exchanger (3) to accommodate a wide range of fuel flow rates and varied operating conditions without increasing the fuel temperature beyond the optimum range.

Description: DIESEL FUEL TEMPERATURE CONTROLLINGMETHOD AND APPARATUS REFERENCE TO PRIOR APPLICATION This application claims priority to Provisional Application Serial No. 60/160,597 filed October 20, 1999 and entitled "Diesel Fuel Temperature Controller & Stabilizer." Field of the Invention The present invention generally relates to the field of energy sources and more particularly, is directed to a method and apparatus for controlling and stabilizing the temperature of diesel fuel at the optimum temperature range. The invention uses a plate type heat exchanger and a maintenance free mechanically actuated flow control valve on the heat source medium. BACKGROUND OF THE INVENTION Tests have demonstrated that the waxes and hydrocarbons in diesel fuel become less viscous when heated to an optimum temperature range. The reduction in viscosity improves the atomization and spray pattern when the fuel is injected into the cylinder of a diesel engine. As a result, the fuel burns more efficiently and completely. The benefit to the diesel engine operator is less smoke and emissions, and an improvement in fuel economy. However, if the diesel fuel is heated past the optimum range, the benefits diminish because of loss in BTU value. Diesel engines typically circulate the diesel fuel from the tank to the engine and unused fuel is circulated back to the fuel tank. The rates of fuel flow can vary dramatically from one manufacturer to another by as much as 90 gallons per hour. The fuel circulation flow can vary from 20 to 110 gallons per hour for truck engines, particularly as new engines with electronic injection are introduced to the market. Heat exchangers for heating diesel fuel are known in the art which use the engine's coolant as the heat source. Although efficient for a certain volume of fuel flow, such exchangers are not designed to handle large variations in the volume of fuel flow. As a result, a method of controlling the fuel temperature was not always required which left the heat exchanger unable to perform its function. In addition, some heat exchangers are difficult to install and require complicated engine modifications . A number of specific examples of fuel heaters are known in the art. For instance, U.S. Patent No. 5,218,944 issued to Leonard, discloses a fuel preheater which separates a portion of the fuel which it preheats in a heat exchanger and then mixes with the remaining unheated fuel under control of a microprocessor to produce a desired optimal temperature. The microprocessor is programmed to maintain minimum differential pressure between the pressure of the fuel leading to injectors, to that in a fuel return line. It takes minutes for engine temperature to stabilize after a change in the mixing valve and then to check whether the vehicle is level, whether the engine speed is constant and then to store the differential pressure. The system then adjusts the mixing valve for hotter temperature setting and goes through the same loop. U.S. Patent No. 5,443,053 issued to Johnson, discloses a fuel heater employing a heat exchanger in which heat is generated by both an electric immersion heater and engine heated coolant or lubricant. Johnson allows an operator monitoring fuel temperature, to adjust the flow rate of the fluid medium manually, by a crank to adjust the fuel temperature. Johnson also discloses use of a fluid medium modulating valve controlled by a relay to control the flow of the fluid medium. However, the nature of the control circuitry is unspecified. U.S. Patent No. 4,858,584 issued to Bridgeman discloses a fuel pre-heater that has an elongate cylindrical outer container housing an inner, concentric tube so as to provide an annular chamber between the two. The fuel line is formed into a coil along the length of the annular chamber and has the inlet and outlet exiting through the ends of the container. Heating medium inlet and outlet connectors for the container are arranged tangentially, at opposite ends of the container and are oriented in opposite directions. The heating medium inlet and outlet is connected into the coolant system while the fuel line inlet and outlet are connected to the fuel line leading to the engine. No control mechanism for the fuel temperature is specified. While the above fuel heaters may represent improvements over their processor heaters, they remain deficient in a number of areas . SUMMARY OF THE INVENTION Accordingly, it is an objective of the present invention to obviate the above-noted shortcomings and disadvantages of prior art approaches to controlling and stabilizing the temperature of diesel fuel . It is a further objective of the present invention to provide a method and apparatus for accurately controlling and stabilizing the temperature of diesel fuel which can be implemented without imposing inconvenience to the user. It is a still further objective of the present invention to provide a method and apparatus for accurately controlling and stabilizing the temperature of diesel fuel which is economical to implement and simple in operation. It is a further objective of the present invention to provide a method and apparatus for accurately controlling and stabilizing the temperature of diesel fuel which is more economical to use than prior art approaches. It is a still further objective of the present invention to provide a method and apparatus for accurately controlling and stabilizing the temperature of diesel fuel which can be readily implemented with existing diesel engines. BRIEF DESCRIPTION OF THE DRAWINGS The novel features of the present invention are set out with particularity in the appended claims, but the invention will be understood more fully and clearly from the following detailed description of the invention as set forth in the accompanying drawings in which: Figure 1 is a block diagram illustrating a diesel fuel engine and the improved method and apparatus of the present invention for controlling and stabilizing fuel temperature; Figure 2 is a time line chart plotting the engine and diesel fuel temperature over time; and Figures 3 is a further time line chart plotting diesel engine temperature and fuel temperatures with and without the method and apparatus of the present invention. The present invention provides an improved method and apparatus for raising and stabilizing the temperature of diesel fuel to the optimum combustion temperature using a highly efficient plate type heat exchanger. The invention utilizes a mechanically actuated flow control valve to regulate the engine coolant flow to maintain and stabilize the fuel temperature in the optimum range regardless of the make of engine or ambient temperature conditions. This allows the heat exchanger to accommodate a wide range of fuel flow rates and varied operating conditions without increasing the fuel temperature beyond the optimum range. Also, it requires no monitoring by the operator and no adjustments (manual or otherwise) due to varied operating conditions . The mechanical flow control valve is a maintenance free method to dynamically control the flow of the coolant which acts as the heat source in order to maintain the fuel temperature within the optimum range of 145 degrees F to 155 degrees F regardless of ambient or operating conditions. It does not rely on an electrical source of power to operate and as a result, is simpler and more reliable in its operation. BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described with reference to the accompanying drawing. As illustrated in Figure 1, the present invention provides an apparatus and method of controlling and stabilizing the temperature of diesel fuel at the optimum temperature range using a plate type heat exchanger and a mechanical flow control valve that reacts to changes in the temperature of the diesel fuel exiting the heat exchanger controlling the heat source medium. Heat exchanger 3 places heated engine coolant within line 2 coming from diesel engine 1 in thermal contact with diesel fuel within line 7 coming from diesel fuel tank 4, thus causing the transfer of heat from the engine coolant to the diesel fuel . This heat transfer raises the temperature of the diesel fuel and delivers it to diesel engine 1 via line 8, valve 11 and line 9 at the optimum stabilized temperature range of 145 degrees F to 155 degrees F. As shown in Figure 1, valve 5 is connected to the engine coolant outlet of heat exchanger 3 and controls the flow of engine coolant through the heat exchanger and return coolant line 10 to engine 1 in order to maintain the fuel temperature within the optimum range. Valve 5 controls the flow of coolant through heat exchanger 3 by opening and closing gradually between a maximum and minimum temperature. Diesel fuel exiting heat exchanger 3 passes through valve 5 and comes in contact with temperature probe 12. Temperature probe 12 is a wax- filled pill with a wax formulation designed to expand and contract in response to changes in diesel fuel temperature. When the diesel fuel exiting the heat exchanger begins to approach the maximum temperature formulated in the wax pill, the wax expands to extend a valve pencil 14. Valve pencil 14 extends into a separate, sealed section 15 of valve 5 where the coolant exiting the heat exchanger passes through and returns to the engine 1 via line 10. Extending valve pencil 14 gradually reduces and stops the flow of the engine coolant exiting heat exchanger 3. Reducing and stopping the flow of coolant through heat exchanger 3 reduces the transfer of heat to the diesel fuel and causes the temperature of the diesel fuel at the diesel fuel delivered to engine 1 to drop. When the temperature of the diesel fuel exiting heat exchanger 3 begins to drop, the wax in the wax pill begins to contract which retracts valve pencil 14 and allows the coolant flow to gradually increase through heat exchanger 3. This increases the transfer of heat to the diesel fuel and again raising its temperature for delivery to engine 1. The wax pill is formulated so that the temperature of the diesel fuel entering the diesel engine is stabilized in the optimum temperature range of 145 degrees F to 155 degrees F for more complete and efficient combustion. With diesel fuel stabilized to the optimum temperature range, the diesel engine will achieve a higher fuel efficiency and will emit less exhaust pollution . Figure 2 is a time line chart plotting the temperature of engine 3 and the temperature of diesel fuel exiting heat exchanger 3 over time in 30 second increments. Figure 3 is a similar time line chart plotting the temperature of engine 1 on line 20, fuel temperature leaving heat exchanger 3 on line 21, fuel temperature for mechanical engines without the present invention on line 22 and fuel temperature for electronic engines without the present invention on line 23. It will be apparent to those skilled in the art that various modifications and variations can be made in the compositions and methods of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims: I CLAIMED : 1. A system for stabilizing diesel fuel at the optimum temperature for more complete and efficient combustion, comprised of a combination of unique components . a) A heat exchanger with engine coolant inlet and outlet and diesel fuel inlet and outlet; b) A mechanically actuated valve connected to the fuel outlet and coolant outlet of the heat exchanger. c) A temperature wax pill with a proprietary wax formula housed in the valve and installed downstream of the diesel fuel outlet that expands and contracts with changes in the diesel fuel temperature in order to extend and retract a valve pencil to dynamically control the flow of the heat exchange medium. 2. A system according to claim 1, wherein said valve is installed on the coolant inlet. 3. That said systems will stabilize the temperature of diesel fuel entering an internal combustion engine at the optimum temperature range of 145 degrees F to 155 degrees F for most complete and efficient combustion. 4. That said systems, when installed and operated on a diesel fueled internal combustion will cause significant reductions in exhaust emissions and significant increases in fuel economy.

Inventors: EPP DAVID, EPP KEN, EPP, DAVID, EPP, KEN
Applicants: EPP DAVID, EPP KEN, EPP, DAVID, EPP, KEN
Application year: 2000
Main classification: F02G5
IPC codes: F01P7, F02G5, F02M31