Patent Publication Number: US-2013233941-A1

Title: Dual solenoid fuel injector with selectively actuable output valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 12/612,440, filed on Nov. 4, 2009 which claims priority to U.S. Provisional Patent Application No. 61/117,897, filed Nov. 25, 2008. The contents of U.S. application Ser. No. 12/612,440 and U.S. Provisional Patent Application No. 61/117,897 are hereby incorporated herein in their entirety by reference, including the drawings, charts, schematics, diagrams and related written description. 
    
    
     FIELD OF THE INVENTION 
     The invention broadly relates to fuel injection systems and more particularly to an injector-ignition fuel injector for an internal combustion engine that is heated and catalyzed with a catalytic activator section. 
     BACKGROUND OF THE INVENTION 
     Much of the world&#39;s energy consumption is dedicated to powering internal combustion based vehicles. Most gasoline and diesel car engines are only 20-30% efficient, such that a major portion of the hydrocarbon fuels is wasted, thereby depleting global resources while producing an excessive quantity of pollutants and greenhouse gasses. As illustrated in  FIG. 1  (prior art), about one third of the energy used by a conventional engine manifests itself as waste heat in the cooling system (coolant load  4 ) while another approximately one third of the energy goes out the tailpipe (exhaust enthalpy  2 ) leaving one third or less to provide useful work (brake power  6 ). At the internal level, these inefficiencies are due to the fact that the conventional combustion process inside a spark ignition gasoline engine or compression ignition diesel engine takes far too long as compared to the rotational dynamics of the piston and crank (i.e., the power stroke of the engine). 
     Conventional fuel injectors can have hydraulically actuated injector pins. The injector pins are typically biased in one direction, either open or closed, by a resilient element, such as a spring. In such injectors, fuel pressure is used to open or close the injector pin against the force of the resilient element. Typically, a fuel injector using a hydraulically actuated injector pin operates by allowing pressurized fuel on opposite sides of the injector pin. The fuel remains separated on the opposite sides by a sealing mechanism. Because the pressurized fuel on both sides of the injector pin are at equilibrium pressure, the inherent force exerted by the spring holds the pin in a closed position. In order to actuate the pin to open against the spring force, the pressurized fuel is drained from one side of the injector pin, thereby causing the remaining pressurized fuel on the other side of the sealing mechanism to push against the biasing of the spring and in turn move the injector pin to an open position. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards a fuel injector having a hydraulically actuated injection pin, also known as an injector stem. In accordance with the invention, the fuel injector provides for more efficient fuel combustion within internal combustion engines, such as vehicle engines. The fuel injector may operate on a wide range of liquid fuels including gasoline, diesel, and various bio-fuels. According to various embodiments of the invention, the fuel injector achieves efficient fuel combustion by fast and responsive actuation, heating the fuel to a supercritical temperature, maintaining fuel at a supercritical pressure, and using a catalyst in the oxidization of the fuel. 
     One embodiment of the invention involves a fuel injector apparatus for an internal combustion engine, such as a vehicle engine, comprising a housing with an upper and lower portion, which contains an injector stem. Typically, the injector stem comprises a lower portion and an upper portion. These assemblies are also referred to herein as the lower injector stem assembly and an upper injector stem assembly. The lower injector stem assembly includes the injector pin, which contacts a seating surface when closed to prevent fuel from entering the combustion chamber of the vehicle engine. The upper and lower injector stem assemblies are attached to each other using conventional methods, e.g., brazing. 
     Within the lower portion of the housing and positioned at the lower injector stem is a first fluid chamber, which is configured to receive pressurized fuel through a fuel duct connected to the first fluid chamber. A second fluid chamber, which is within the upper portion of the housing and positioned at an upper portion of the injector stem, is configured to receive pressurized fuel through an input duct connected to the second fluid chamber. Additionally, an output duct connected to the second fluid chamber allows for fuel drainage from the second fluid chamber. A seal between the first and second fluid chambers separates the fuel within the two chambers. 
     A first valve attached to the input duct is configured to selectively open and close the input duct through actuation, thereby controlling the flow of pressurized fuel into the second fluid chamber. Fuel drainage from the second fluid chamber, in turn, is controlled by an orifice needle hole positioned within the output duct. In some alternative embodiments, a first valve is attached to the output duct and is configured to selectively open and close the output duct through actuation, thereby controlling the flow of fuel drainage from the second fluid chamber. In such embodiments, pressurized fuel flow into the second fluid chamber is controlled by an orifice needle hole positioned within the input duct. In yet other alternative embodiments, a first valve is attached to the input duct and a second valve is attached to the output duct, thereby replacing the use of an orifice needle hole. 
     Attached to the injector stem is a return spring that biases the injector stem to a closed position. In some embodiments of the invention, the return spring is attached to the upper portion of the injector stem. In additional embodiments, the fuel injector is in the closed position when the injector stem is forced downward and, hence, the return spring biases the injector stem downward so that the injector pin is in contact with the injector seat. 
     The first fluid chamber also has a heating element positioned adjacent to the chamber. As such, the heating element is capable of heating up the fuel within the first fluid chamber before it is injected into the combustion chamber of the internal combustion engine. 
     A controller connected to the heating element controls the engagement of the element. The controller is connected to the first valve for selective actuation of the first valve. Further, in embodiments of the invention that utilize a second valve, the controller is also connected to the second vale for the selective actuation of the second valve. 
     In some embodiments, a catalyst is included in the inner sidewall of the first fluid chamber. In some alternative embodiments, a catalyst is attached to the lower portion of the injector stem. Usually, when the catalyst is attached to the lower portion of the injector stem, the catalytic element is applied to the outer surface of the lower portion of the injector stem. Generally, one of the purposes served by the catalysts is to assist in the oxidation of fuel before it enters the combustion chamber of the internal combustion engine. Some embodiments of the invention feature only one of the surfaces (either the inner sidewall of first fluid chamber or the outer surface of lower portion of the injector stem) being coated with the catalytic element. In other embodiments, both surfaces are coated with the catalytic element. 
     In other embodiments of the invention, an electromechanical valve is used as the first valve. Similarly, various embodiments use an electromechanical valve as the second valve. The use of electromechanical valve allows fast filling and draining of the first fluid chamber. In some embodiments that employ electromechanical valves, these valves comprise solenoids. The solenoid is connected and controlled by the controller described above. 
     In some embodiments, a proximity sensor can be positioned in the upper portion of the housing to monitor the position of the injector stem. This proximity sensor is connected to the controller. 
     In preferred embodiments, the fuel within first fluid chamber is maintained at a supercritical state. Specifically, in some such embodiments, the fuel is maintained in at either a supercritical temperature, a supercritical pressure, or both. Generally, maintaining fuel at a supercritical state before it is injected into the combustion chamber of the internal combustion engine yields more efficient combustion of the fuel. In some embodiments, fuel within the first fluid chamber is maintained at a supercritical temperature vis-à-vis the heating element. In other embodiments, fuel within the first fluid chamber is maintained at a supercritical pressure by the injector stem and the fuel duct. 
     Other features and aspects of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the features in accordance with embodiments of the invention. The summary is not intended to limit the scope of the invention, which is defined solely by the claims attached hereto. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention, in accordance with one or more various embodiments, is described in detail with reference to the following figures. The drawings are provided for purposes of illustration only and merely depict typical or example embodiments of the invention. These drawings are provided to facilitate the reader&#39;s understanding of the invention and shall not be considered limiting of the breadth, scope, or applicability of the invention. It should be noted that for clarity and ease of illustration these drawings are not necessarily made to scale. 
         FIG. 1  (prior art) is a diagram that illustrates the inefficiencies in a conventional combustion process inside a spark ignition gasoline engine or a compression ignition diesel engine. 
         FIG. 2  depicts a cross section of a dual solenoid fuel injector constructed in accordance with the principles of the present invention. 
         FIG. 3  depicts a cross section of the upper portion of a dual solenoid fuel injector constructed in accordance with the principles of the present invention. 
         FIG. 4  depicts a cross section of the lower portion of a dual solenoid fuel injector constructed in accordance with the principles of the present invention. 
         FIG. 5  depicts a front perspective view of a dual solenoid fuel injector constructed in accordance with principles of the present invention. 
         FIG. 6  depicts a front view of a dual solenoid fuel injector constructed in accordance with principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s). 
     In accordance with the principles of the present invention, an internal combustion engine fuel injector having a hydraulically actuated injection pin, also referred to herein as an injector stem, is provided. According to various embodiments of the invention, the fuel injector achieves efficient fuel combustion by (i) fast and responsive actuation, (ii) heating the fuel to a supercritical temperature, (iii) maintaining the fuel at a supercritical pressure, and (iv) using a catalyst in the oxidization of the fuel before it enters the combustion chamber of the internal combustion engine. The fuel injector may operate on a wide range of liquid fuels including gasoline, diesel, and various bio-fuels. 
     In accordance with the present invention, the fuel injector  10  depicted in  FIG. 2-4  comprises two electromechanical valves ( 14  and  52 ), a heating element  32 , and a catalyst material within a lower fluid chamber  36 . 
     More particularly,  FIG. 2  depicts a cross section of the fuel injector  10  constructed in accordance with the principles of the present invention. An enlarged view of the upper portion of the fuel injector  10  is provided in  FIG. 3 , while an enlarged view of the lower portion of the fuel injector  10  is provided in  FIG. 4 . 
     Referring to  FIG. 2 , the fuel injector  10  has a lower housing  54  connected to an upper housing  22 . Usually, the lower housing  54  and upper housing  22  are connected to each other by bolts extending through the housing bodies. The lower housing  54  (also referred to as outer housing  54 ) is concentric and coaxial with an inner housing  40 . 
     Now referring to  FIG. 4 , the lower housing  54  is typically made of stainless steel, however, any appropriate metal can be used. The outer housing  54  has a lower portion having an injector seat  38 . The injector seat  38  is the inner surface of an orifice that allows for fuel to exit the fuel injector  10  into the combustion chamber of an internal combustion engine. While some embodiments of the invention have only one orifice leading out of the fuel injector, other embodiments can have a plurality of such orifices. 
     With further reference to  FIG. 4 , inner housing  40  is positioned concentrically within the outer housing  54 . The inner housing  40  has a hollow inner cavity and an inner surface  34 . The inner surface  34  allows for the sliding movement of the injector stem assembly, comprising an upper stem  26  and a lower stem  30 . Although the diameter of the hollow inner cavity can be any desired value, in some preferred embodiments of the invention the diameter is about 4 mm. At the bottom of the hollow inner cavity is the lower fluid chamber  36 , from which fuel exits the fuel injector  10  during operation. The lower fluid chamber  36  is adjacent to the injector seat  38  and is formed between the lower stem  30  and the inner housing  40 . The lower fluid chamber  36  is connected to an input port that allows for pressurized fuel to be delivered into the lower fluid chamber  36 . 
     With continued reference to  FIG. 4 , the lower stem assembly  30  and the inner surface  34  of the inner housing  40  form a seal to prevent fluid within the lower fluid chamber  36 , which is below the lower stem  30 , from contacting or mixing with fluid from the upper stem assembly  26 . Any appropriate sealing mechanism  28 , such as precision ground seals, bellows seals, o-ring seals, diaphragm, elastomers, or energized seals, may be employed to prevent fluid within the lower fluid chamber  36  from contacting with fluid from the upper stem assembly  26 . 
     In preferred embodiments, the inner housing  40  adjacent the lower fluid chamber contains a heating element  32 . The heating element  32  can be a resistance coil or any other suitable means to allow for the selective heating of the inner surface of the inner housing  40 . The heating element  32  allows for the fuel in the lower fluid chamber  36  to be heated to a temperature of 600 degrees Fahrenheit to 1300 degrees Fahrenheit, allowing the fuel to reach a supercritical temperature that allows for more efficient combustion. The heating element  32  extends from the injector seat  38  to the top of the lower portion of the lower stem  30  to form a consistent heating of the entire lower fluid chamber  36 . 
     In additional preferred embodiments, a catalyst element is included in the lower fluid chamber  36 . In some of these embodiments, the catalyst element can be a coating, plating, surface treatment, wire winding or bonding that is coated on, attached to, or formed integrally with the lower stem  30 , the inner surface  34  of the inner housing  40 , or both. In a specific preferred embodiment, the catalyst element forms part of the outer surface of the lower stem  30 . The catalyst element can also be formed on a portion of the inner wall of the inner housing  40  adjacent the lower fluid chamber  36 . Forming the catalyst on either surface allows for the fuel contained in the lower fluid chamber to react with the catalyst before it enters the combustion chamber, allowing for a more efficient burning of the fuel. Preferably, the catalyst is nickel with about 5% molybdenum, however, a person of ordinary skill in the art would appreciate that a number of appropriate catalysts can be used, such as nickel, nickel-molybdenum, alpha alumina, aluminum silicon dioxide, other air electrode oxygen reduction catalysts, and other catalysts used for hydrocarbon cracking. 
     With reference to  FIG. 2 , an injector stem  26 ,  30  is depicted along the centerline of the fuel injector  10 . The injector stem (also referred to as the injector stem assembly  26 ,  30 ) is housed within the lower housing  54 . As previously noted, the injector stem  26 ,  30  comprises an upper stem  26  and lower stem  30 , wherein the upper injector stem  26  and lower injector stem assembly  30  are attached to each other. Some embodiments of the invention use brazing as the method for attaching the upper stem  26  to the lower stem  30 . A person of ordinary skill in the art would appreciate that there are other suitable methods for attachment, without departing from the scope of the invention. Additionally, a proximity sensor  12  is positioned in the upper housing  22  allowing for sensing of the current position of the stem assembly. 
     With resumed reference to  FIG. 4 , the bottom end of lower stem  30  is configured with a double angled surface such that when the fuel injector  10  is in the closed position, the double angled surface makes contact with the injector seat  38 . When the double angled surface makes contact with the injector seat  38 , a fluid tight seal is formed, preventing any fuel in the lower fluid chamber  36  from escaping through the orifice leading out of the fuel injector. 
     Referring now to  FIG. 3 , a return spring assembly  24  is positioned at the upper stem  26  and configured such that the force the spring  24  exerts against flange  42  forces the upper stem  26  in downward direction. With the upper stem  26  forced downward, the lower stem  30  is also forced downward, causing the double angled surface of the lower stem  30  to make contact with the injector seat  38 . As previously noted, when the double angled surface makes contact with the injector seat  38 , a fluid tight seal is formed, preventing any fuel in the lower fluid chamber  36  from escaping the fuel injector  10  and entering the combustion chamber of the internal combustion engine. Those of ordinary skill in the art would appreciate that the return spring assembly  24  could be substituted using any suitable biasing element. 
     Continuing reference to  FIG. 3 , the fuel injector  10  includes a pilot valve assembly ( 14  and  52 ) that controls the hydraulic pressure acting on the upper stem assembly  26 . The hydraulic pressure, in turn, is used to lift and lower the entire injection steam assembly, thereby lifting and lowering the double angled surface of the lower stem  30  that makes contact with the injector seat  38 . More specifically, an upper fluid chamber  44 , that is part of the pilot valve assembly ( 14  and  52 ), provides the hydraulic pressure on the upper stem  26  in the form of pressurized fuel. The upper fluid chamber  44  is configured for fuel to be contained therein at a pressure which is substantially equal to the pressure of the lower fluid chamber  36 . To facilitate this, the upper chamber  44  has an inlet duct  20  that allows for a constant flow of fuel to be pumped into the chamber  44 . An outlet duct  46  is also provided for the upper fluid chamber  44 , allowing for the upper fluid chamber  44  to be drained and the fuel to be returned to the fuel reservoir or tank. 
     With continued reference to  FIG. 3 , fuel provided to the inlet duct  20  via input duct  102 . Likewise, fuel is drained through the outlet duct  46  into output duct  104 , which returns the fuel to a reservoir or tank. The illustrated fuel injector  10  has an input electromechanical valve  14  for controlling the flow of fuel to the upper chamber  44 , and an output electromechanical valve  52  for controlling the flow of fuel out of the upper chamber  44 . The input electromechanical valve  14  is connected to a poppet valve  18  and has a spring  16  that biases the poppet valve into a normally open position, thereby allowing fuel into the upper chamber  44 . Output electromechanical valve  52  is connected to a poppet valve  48  with a spring  50  that biases the poppet valve  52  into a normally closed position, thereby preventing fuel from draining from the upper fluid chamber  44 . The respective position of the poppet valves ( 18  and  48 ) are reversed when their respective electromechanical valve is activated. Hence, when the upper fluid chamber  44  needs to be filled, the input electromechanical valve  14  and output mechanical valve  52  are deactivated. When the upper fluid chamber  44  needs to be drained, both the input electromechanical valve  14  and output mechanical valve  52  are activated. The specific type of electromechanical valve used in the depicted fuel injector  10  is a solenoid. The input solenoid  14  is positioned in fluid connection with a fuel inlet duct  20 , and the output solenoid  52  is positioned in fluid connection with the outlet duct  46 . Each solenoid is connected to a controller that controls solenoid actuation. 
     In some embodiments of the invention, an orifice needle hole is positioned in the input duct  102  and used to control the flow of fuel into the input duct  102 , while an electromechanical valve is positioned in fluid connection with the outlet duct  104  and controls the flow of drainage from the upper fluid chamber  44 . In alternative embodiments of the invention, an orifice needle hole is positioned in the output duct  104  and used to control the flow of fuel out of the output duct  104 , while an electromechanical valve is positioned in fluid connection with the input duct  102  and controls the flow of fuel into the upper fluid chamber  44 . 
     Although  FIG. 2-6  depict a fuel injector using dual solenoid actuators in accordance with the present invention, a person of ordinary skill in the art would appreciate that any type of actuator can be used to control the poppet valves ( 18  and  48 ). For example, in alternative embodiments of the invention, piezo elements can be used in place of the solenoid actuators ( 14  and  52 ). 
       FIG. 5  depicts a front perspective view of the dual solenoid fuel injector  10  depicted in  FIG. 2-4 .  FIG. 6  depicts a front view of the same dual solenoid fuel injector  10 . In addition to the components previously described with respect  FIG. 2-4 , both  FIG. 5  and  FIG. 6  illustrate fuel duct  108 , which supplies pressurized fuel to the input port of the lower fluid chamber  36 . 
     Actuation of the Injector 
     When the fuel injector  10  is in a closed state, pressurized fuel is pumped into the lower fluid chamber  36  through the fuel duct  108 . The fuel pressure pushes the lower stem  30  upwards and away from the injector seat  38 . The upper fluid chamber  44  is also filled with fuel pressurized at substantially the same pressure as the lower fluid chamber  36 . The fuel is allowed to flow into the upper fluid chamber  44  by way of the inlet duct  20 , which is attached to the input duct  102 . When the fluid pressures in the upper fluid chamber  44  and lower fluid chamber  36  are substantially equal and opposite to each other, the injector stem assembly is in a neutral pressure state, allowing the return spring  24  to be the only force acting on the injector stem assembly. Because the return spring  24  exerts a downward force on the injector assembly (as previously discussed), the injector stem assembly is biased closed when the fuel pressure in the upper fluid chamber  44  and the lower fluid chamber  36  are equal. 
     In order to open the fuel injector  10 , the input electromechanical valve  14  is activated, moving the input valve to the “closed” position, while the output electromechanical valve  52  is activated, thereby moving the output valve into the “open” position. When the outlet duct  46  is opened, the fluid in the upper chamber is drained back to a fuel reservoir. Because the pressure in the upper chamber  44  is now released, the pressure in the lower chamber  36  is allowed to push the lower stem  30 , and thereby the entire injector stem assembly, in an upward direction away from the injector seat  38  and against the force exerted by the return spring  24 . This opens the fuel injector  10 , allowing the fuel in the lower chamber  36  to be released from the fuel injector  10  and into the combustion chamber. 
     To close the fuel injector  10 , the input electromechanical valve  14  is deactivated, moving the input valve to the “open” position, while the output electromechanical valve  52  is now deactivated, thereby returning the output valve to the “closed” position. As a result, the inlet duct  20  allows fuel to fill and pressurize the upper chamber  44 . The pressurization of the upper fluid chamber  44  along with the force of the return spring  24  pushes the stem assembly downward toward the injector seat  38 . The upper and lower fluid chambers ( 44  and  36 ) are subsequently allowed to fill with fuel, displacing the injector  10  back into the original closed state. 
     Thus, it is seen that a dual solenoid fuel injector for an internal combustion engine is provided. One skilled in the art will appreciate that the present invention can be practiced by other than the various embodiments and preferred embodiments, which are presented in this description for purposes of illustration and not of limitation, and the present invention is limited only by the claims that follow. It is noted that equivalents for the particular embodiments discussed in this description may practice the invention as well. 
     While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not of limitation. Likewise, the various diagrams may depict an example architectural or other configuration for the invention, which is done to aid in understanding the features and functionality that may be included in the invention. The invention is not restricted to the illustrated example architectures or configurations, but the desired features may be implemented using a variety of alternative architectures and configurations. Indeed, it will be apparent to one of skill in the art how alternative functional, logical or physical partitioning and configurations may be implemented to implement the desired features of the present invention. Also, a multitude of different constituent module names other than those depicted herein may be applied to the various partitions. Additionally, with regard to flow diagrams, operational descriptions and method claims, the order in which the steps are presented herein shall not mandate that various embodiments be implemented to perform the recited functionality in the same order unless the context dictates otherwise. 
     Although the invention is described above in terms of various exemplary embodiments and implementations, it should be understood that the various features, aspects and functionality described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment with which they are described, but instead may be applied, alone or in various combinations, to one or more of the other embodiments of the invention, whether or not such embodiments are described and whether or not such features are presented as being a part of a described embodiment. Thus the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments. 
     Terms and phrases used in this document, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing: the term “including” should be read as meaning “including, without limitation” or the like; the term “example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof; the terms “a” or “an” should be read as meaning “at least one,” “one or more” or the like; and adjectives such as “conventional,” “traditional,” “normal,” “standard,” “known” and terms of similar meaning should not be construed as limiting the item described to a given time period or to an item available as of a given time, but instead should be read to encompass conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future. Likewise, where this document refers to technologies that would be apparent or known to one of ordinary skill in the art, such technologies encompass those apparent or known to the skilled artisan now or at any time in the future. 
     A group of items linked with the conjunction “and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as “and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction “or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as “and/or” unless expressly stated otherwise. Furthermore, although items, elements or components of the invention may be described or claimed in the singular, the plural is contemplated to be within the scope thereof unless limitation to the singular is explicitly stated. 
     The presence of broadening words and phrases such as “one or more,” “at least,” “but not limited to” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances where such broadening phrases may be absent. The use of the term “module” does not imply that the components or functionality described or claimed as part of the module are all configured in a common package. Indeed, any or all of the various components of a module, whether control logic or other components, may be combined in a single package or separately maintained and may further be distributed across multiple locations. 
     Additionally, the various embodiments set forth herein are described in terms of exemplary block diagrams, flow charts and other illustrations. As will become apparent to one of ordinary skill in the art after reading this document, the illustrated embodiments and their various alternatives may be implemented without confinement to the illustrated examples. For example, block diagrams and their accompanying description should not be construed as mandating a particular architecture or configuration.