Patent Publication Number: US-2005123873-A1

Title: Modulating oil fuel delivery system

Description:
BACKGROUND OF INVENTION  
      This invention relates generally to heating appliances such as furnaces and boilers, specifically for the purpose of pumping oil to an oil combustion system.  
      This invention is a modulating oil delivery system used in conjunction with an oil combustion system on a furnace, boiler or other heating appliance. Its purpose is to vary the flow rate of oil to a burner based upon either a boiler&#39;s water temperature, a furnace&#39;s air temperature, time and rate or both time, rate and temperature.  
      Typically, when a room or boiler calls for heat, the combustion system of the furnace or boiler ignites and runs on a set, usually high, firing rate. This continues until the thermostat of a room or aquastat of a boiler senses the temperature has risen to a set temperature which then de-energizes the combustion system, shutting it down, and thus ending the burn cycle. This is often referred to as an on off operation.  
      A new method of obtaining higher efficiencies with furnaces and boilers is to vary or change the flow rate of fuel to the combustion system based upon the rise or lowering of the temperature of either a boiler&#39;s water temperature or a furnace&#39;s circulating air temperature. As the water or air temperature rises, the modulating fuel system lowers the fuel flow rate to the combustion system. Likewise, when the air or water temperature begins to lower, the modulating system increases the fuel flow rate proportionally.  
      Rather than a full blast of heat continuously being turned on and off with high fluctuations of temperature, the modulating system keeps more of a consistent temperature with in a boiler or furnace. This results in greater efficiencies in fuel consumption, less wear and tear on the boiler or furnace internals, and less temperature fluctuation of the space being heated creating a more comfortable heated environment.  
      Short cycling of the combustion system on a boiler or furnace is often a problem. Short cycling is a continuous on off operation of a combustion system with short burn cycles. It happens as a result of too fast of temperature increase within a boiler or heated area air space with no place to put excess heat. In a hydronic heating system, a heat storage tank is often used to provide a means of storing excess heat generated by the heat source such as a boiler. Like a battery, the heat storage tank allows the boiler to run longer during a burn cycle and therefore fewer burn cycles. Heat storage tanks are very expensive, they take up floor space and involve expensive labor, pumps, controls and many other components to install it into a hydronic heating system. A modulating fuel system has the capability to eliminate short cycling and thus the need for heat storages tanks.  
      In gas furnaces and boilers, modulation of the fuel to the combustion system is usually accomplished by changing the opening position of a gas valve with a motorized actuator wired to a modulating controller. The modulating controller senses the boiler&#39;s water or furnace&#39;s air temperature and adjusts the gas flow accordingly as was described above. There are several complications with pumping oil that make modulating oil burners more difficult that this invention solves.  
      Multi oil combustion systems are most prone to flame failure at start up. If the fuel and air mixture isn&#39;t perfect for ignition, then failure to establish a flame takes place and the burner&#39;s controller will shut the system down. Usually too much oil is shot out at start up from a solenoid valve that snaps open allowing oil under pressure to rush out which creates an over fueling condition. When ignition of the oil fuel occurs then a sudden burst of fire causing a back draft will occur creating a hazardous condition. This is often called a hard start. This improved pumping system has the ability to accelerate the oil flow at start up to prevent over fueling at start up. This allows the flame to become established at a lower rate of combustion and gradually increase to the desired combustion rate over a set predetermined length of time creating a much softer and reliable start up.  
      U.S. Pat. No. 5,372,484 to Briggs et al. in Dec. of 1994 shows a positive displacement pump used in conjunction with an internal valve with in the pump to regulate pressure leaving the pumping system. This system is an on off pumping system incapable of varying the oil flow based upon anything but manual adjustment.  
      U.S. Pat. No. 5,240,405 to Schubach et al. in Aug. of 1993 shows an oil pumping system invention which is manually adjusted. Schubach&#39;s patent specifically describes how an operator can manually fine tune and adjust the oil flow rate and thus the flame size by making manual adjustments. This invention also is an on off pumping system incapable of varying the flow of oil based on a function of time, the heating appliance&#39;s heating medium&#39;s temperature, or both.  
      Historically, pumping oils of various viscosities to a multi oil combustion system has had many issues and challenges in attempting to establish constant flow with variable viscosities. This intellectual smart pumping system supersedes these issues because the demand to achieve constant flow is eliminated and replaced with a programmable logic controller that controls the flow according to demand regardless of oil viscosity.  
     SUMMARY OF INVENTION  
      Disclosed herein, is a modulating oil fuel delivery system that controls the oil flow rate to a combustion system based on a function of time and rate, a sensed temperature input or both time and rate and temperature.  
      It is an object of this invention that the oil fuel efficiency of an oil combustion system be increased as a function of modulating the oil fuel flow and thus flame size versus an on-off operation.  
      It is a further object of this invention that the lifespan of a heating appliance such as a boiler or furnace be increased do to a more consistent internal operating temperature.  
      It is a further object of this invention that the cost of installing a hydronic heating system is reduced due to the fact that a heat storage tank may be eliminated with this invention.  
      It is further an object of this invention that the reliability of a multi oil combustion system is significantly increased due to creating a smoother start up. 
    
    
     BRIEF DESCRIPTION OF DRAWING  
       FIG. 1  is a schematic view of the modulating oil fuel delivery system of the present invention. 
    
    
     DETAILED DESCRIPTION  
      A preferred embodiment of the present modulating oil fuel pumping system is illustrated by  FIG. 1 .  
      This invention changes the flow rate of oil to a burner and thus the flame size using an electronic modulating controller  1  connected to, via wiring  3  and  4 , a variable speed motor  5  that is coupled to and drives an oil pump  7 . Oil pump  7  draws oil from an oil source  8 , via plumbing  9  and pumps the oil to a combustion system  11  via plumbing  10 . Modulating controller  1  will be abbreviated as MCI. When MCI increases the speed of motor  5 , which is coupled to and drives oil pump  7 , the oil flow rate increases and when MCI slows the speed of motor  5  the flow rate decreases.  
      MCI energizes motor  5 , varying the oil flow rate, as a function of a sensed temperature using a temperature sensor  13 , connected via wiring  14 , connected to a heating appliance  12  such as a boiler or furnace. Or, MCI can control motor  5  as a function of time and rate or both time and rate and temperature.  
      For modulation as a function of time and rate example, when heating appliance  12  calls for heat, MCI may start motor  5  on low rpm producing a low fire and then increase the rpm of motor  5  producing a high fire over a predetermined amount of time until the heating appliance&#39;s thermostat is satisfied. The pumping system is switched on and off by combustion system  11 . With this method, MCI does not need to sense the temperature of the heating medium of heating appliance  12 .  
      With temperature sensor  13  connected via wiring  14  to MCI, modulation of oil fuel flow rate can be controlled as a function of temperature. For example, when heating appliance  12  calls for heat, MCI can sense the temperature of the heating medium of heating appliance  12  and increase the oil flow with temperature decline and decrease the flow with temperature increase in order to maintain set high and low temperature limits. Therefore, this invention further includes temperature sensor  13  and wiring  14  for providing a temperature reading to MCI. This depends on what MCI is used and how it is configured and programmed to work with heating appliance  12 .  
      There are many manufacturers of modulating controllers. Honeywell manufactures several controllers, model numbers UDC1000, UDC1500 and BC7000. Johnson Controls also manufactures a controller, model number FX05. Programmable logic controllers can also be set up and programmed to perform the functions of a modulating controller. Some modulating controllers can directly power motor  5  while some can&#39;t. The modulating controller may or may not need an additional electronic module or a circuit board  2  added to convert the output signal to a useable electrical current to power the motor which drives the oil pump.  
      Primarily, there are two methods of atomizing and spraying oil, air atomization and pressure atomization. With the pressure atomization method, the oil is highly pressurized by the oil pumping system and forced out of a small orifice of a nozzle. This method is primarily used with oils of lighter density such as number 1 and number 2 fuel oils. Thicker oils do not atomize well with the pressure method because of the small orifice size and physical complexities of atomizing heavier fluids.  
      Thicker oils typically are preheated and use the air atomization method utilizing an air atomization nozzle. Air atomization nozzles have a large fluid opening compared to pressure type nozzles. Compressed air is mixed with oil inside the nozzle and sprayed out producing a spray and atomization of oil. With this method, the oil needs to be delivered to combustion system  11  at an even flow with out creating high pressure.  
      With the pressure atomization method, the oil pump must be driven at higher rpm&#39;s to generate the oil pressure needed. Typically this is accomplished by driving the oil pump directly at around 3,450 rpm&#39;s with the burner motor. With the air atomization method, the oil pump is driven at low rpm&#39;s to push the oil under low pressure to the nozzle. Typically this is accomplished by coupling the oil pump to a gear motor which reduces the rpm of the output shaft of the motor connected to the oil pump input shaft. Another method is using pulleys and a belt to couple the motor to the pump where a smaller pulley is mounted on the motor output shaft and a larger pulley is mounted on the input shaft of the oil pump. This invention works on both methods of pumping and atomization just described. Connection  6  between motor  5  and pump  7  may be either direct drive or of a gear reduction type. Therefore, this invention further includes a means of a gear reduction connection between the motor and oil pump for use with the air atomization method.  
      It will be appreciated that this invention provides a means of modulating the firing rate of an oil fired combustion system producing many advantages to the end user as was described above. Although the detailed description above contains many specificities, these should not be construed as limiting the scope of this invention, but rather as an exemplification of preferred embodiments thereof. Many other variations are possible. For example, either an AC or DC motor  5  can be used. Whether or not an additional circuit board  2 , or boards, is needed depends on the modulating controller being used. The oil pump  7  sizing will vary depending on the flow needed to combustion system  11  as required by heating appliance  12 . If the modulation operates on a function of temperature then a temperature sensor  13  and wiring  14  will be needed and connected to MCI.  
      Many of the fastening, connection and wiring means, and other components utilized in this invention are widely known and used in the field of the invention described. Their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art or science, and they will not therefore be discussed in significant detail.  
      Further, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention. This invention comprises a unique combination of elements, each element of which can be accomplished by one of several different means or variations for a specific application of this invention. The practice of a specific application of any element may already be widely known or used in the art or by persons skilled in the art or science, and each will not therefore be discussed in significant detail.  
      Thus, the scope of this invention should be determined not solely by the embodiments illustrated, but by the appended claims and their legal equivalents.