Patent Publication Number: US-2023160334-A1

Title: Fuel supply system for active pre-combustor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the 371 application of PCT Application No. PCT/CN2020/140156, filed on Dec. 28, 2020, which is based upon and claims priority to Chinese Patent Application No. 202011124960.0, filed Oct. 20, 2020, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present application relates to the technical field of vehicle motors, and more particularly, to a fuel supply system for an active pre-combustor. 
     BACKGROUND 
     With the development of gasoline engine technology and increasingly strict emission regulations and fuel consumption regulations, traditional gasoline engine technologies have been faced with more severe challenges, and improving a thermal efficiency of gasoline engines while reducing fuel consumption has always been a goal pursued by major manufacturers. 
     Lean combustion and exhaust gas recirculation (EGR) is one of the effective methods to improve a thermal efficiency of gasoline engines. It can be shown from the existing experimental data that, if a gasoline engine adopts a lean combustion with an excess air coefficient (lambda) between 1 and 1.5, the thermal efficiency may be improved. However, a three-way catalytic converter cannot be adopted due to a deviation from the theoretical air-fuel ratio, and it is required to be adopted expensive NOx after-treatment equipment to meet emission regulations. If the gasoline engine adopts an ultra-lean combustion with an excess air coefficient greater than 1.5, the thermal efficiency of the gasoline engine can be improved without causing excessive NOx emissions. On the other hand, mixed fuel with a high EGR rate (EGR rate&gt;20%) can be used to reduce the pumping loss, reduce the knocking tendency, and improve the thermal efficiency. 
     However, conventional spark plugs are difficult to ignite ultra-lean gas mixtures or gas mixtures with a high EGR rate, and the combustion of ultra-lean gas mixtures or gas mixtures with high EGR rates requires a high-energy ignition device to meet the application requirements. Therefore, the pre-combustor technology has received widespread attention. 
     SUMMARY 
     There is provided a fuel supply system for an active pre-combustor. The technical solution is as below: 
     According to embodiments of the present disclosure, there is provided a fuel supply system for the active pre-combustor, comprising a main combustor comprising a cylinder head, a cylinder body and a piston; a pre-combustor assembly; and a plunger air pump assembly; wherein the pre-combustor assembly is communicated with the main combustor, and the plunger air pump assembly is communicated with the pre-combustor assembly, and wherein the plunger air pump assembly is capable of mixing air and fuel into mixed fuel and delivering the mixed fuel to the pre-combustor assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    illustrates a view of a fuel supply system for an active pre-combustor according to the present application. 
         FIG.  2    illustrates a view of a fuel supply pipeline assembly according to the present application. 
         FIG.  3    illustrates a view of a plunger air pump rod at a top dead center according to the present application. 
         FIG.  4    illustrates a view of the plunger air pump rod at a bottom dead center according to the present application. 
     
    
    
     DETAILED DESCRIPTION 
     Specific embodiments of the present application will be described in further detail below with reference to the accompanying drawings and embodiments. The following embodiments are intended to illustrate the present application, but not to limit the scope of the present application. 
     The terms such as “first”, “second”, “third” and “fourth” in the description and claims of the present application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. 
     Referring to  FIG.  1   , the fuel supply system of the active pre-combustor of the present application includes a cylinder assembly  10 , a pre-combustor assembly  20  and a plunger air pump assembly  30 . The cylinder assembly  10  includes a main combustor  16 , and the main combustor  16  includes a cylinder head  11 , a cylinder body  14  and a piston  13 . The cylinder assembly  10  further includes an intake valve  15  and an exhaust valve  12  for gas intake and gas exhaust, respectively. The plunger air pump assembly  30  includes a fuel supply pipeline assembly, and the fuel supply pipeline assembly is communicated with an engine and a plunger air pump cavity  301 . The pre-combustor assembly  20  is communicated with the main combustor  16 , and the plunger air pump assembly  30  is communicated with the pre-combustor assembly  20 . 
     Further, the plunger air pump assembly  30  further includes a plunger air pump driver  31 , a plunger air pump rod  32  and a plunger air pump spring  33 . The plunger air pump driver  31  is configured to drive the plunger air pump rod  32 , and the plunger air pump spring  33  is wound on the plunger air pump rod  32 , so that the plunger air pump rod  32  is capable of sliding up and down in the plunger air pump cavity  301  under a driving of the plunger air pump driver  31  and the plunger air pump spring  33 . In this embodiment, the plunger air pump rod  32  further includes a plunger air pump piston  34 , and the plunger air pump piston  34  is fixedly connected to the bottom end of the plunger air pump rod  32  and is directly driven by the plunger air pump rod  32 , which is capable of sliding up and down in the plunger air pump cavity  301  under the driving of the plunger air pump driver  31  and the plunger air pump spring  33 . The plunger air pump driver  31  is a cam structure arranged on a valve camshaft. A ratio of a frequency at which the plunger air pump driver  31  drives the plunger air pump rod  32  and a frequency at which the piston  13  drives an engine crankshaft is 1:2. That is, every time the engine crankshaft rotates twice, the plunger air pump driver  31  rotates once. In other embodiments, the ratio of the frequency at which the plunger air pump driver  31  drives the plunger air pump rod  32  and the frequency at which the piston  13  drives the engine crankshaft may also be 1:1 or 2:1, as long as it is ensured that the plunger air pump rod  32  always moves in an opposite direction to the piston  13  or the plunger air pump rod  32  is kept stationary. The plunger air pump driver  31  may be arranged on an independent camshaft independent of the valve camshaft. If required, the plunger air pump driver  31  may also be an electric mechanism, an electromagnetic mechanism or a crank-link mechanism, as long as it can reciprocally drive the plunger air pump rod  32  at a fixed frequency. 
     Further, the pre-combustor assembly  20  includes a spark plug  21  and a pre-combustor housing  22 . The spark plug  21  is fixed on the pre-combustor housing  22 , the spark plug  21  is capable of igniting the mixed fuel in the pre-combustor cavity  221 . The pre-combustor housing  22  is provided with pre-combustor injection holes  222 , and the pre-combustor assembly  20  is communicated with the main combustor  16  through the pre-combustor injection holes  222 . The plunger air pump cavity  301  is located in the pre-combustor housing  22  and is formed between the plunger air pump piston  34  and the pre-combustor housing  22 . The plunger air pump rod  32  moves up and down along the pre-combustor housing  22 , and is capable of controlling the plunger air pump cavity  301  to be communicated with or separated from the pre-combustor cavity  221 . In this embodiment, the plunger air pump cavity  301  is cylindrical, and the pre-combustor housing  22  is in a shape of an inverted cone. It can be understood that the shapes of the plunger air pump cavity  301  and the pre-combustor housing  22  may also be designed and arranged according to practical needs of the cylinder body  14 . The pre-combustor injection holes  222  are arranged at a bottom of the pre-combustor housing  22 , and the plurality of pre-combustor injection holes  222  are evenly arranged along an axis of the pre-combustor housing  22 . The spark plug  21  is arranged on one side of a top of the pre-combustor housing  22 , and the plunger air pump assembly  30  is arranged on the other side of the top of the pre-combustor housing  22 . In this embodiment, mounting angles of the cylinder body  14 , the spark plug  21  and the plunger air pump assembly  30  are only illustrated as an example. The plunger air pump assembly  30  may be mounted at any reasonable angle relative to the cylinder body  14  and spark plug  21 . 
     Further, as shown in  FIGS.  3 - 4   , the pre-combustor housing  22  is further provided with a first contact surface  223  and a second contact surface  224 . The first contact surface  223  contacts a lower end of the plunger air pump spring  33  and limits the plunger air pump spring  33 , and the second contact surface  224  contacts a lower end of the plunger air pump rod  32  and limits the plunger air pump rod  32 . In this embodiment, the first contact surface  223  is provided on an outer wall of the pre-combustor housing  22 , and the second contact surface  224  is provided on a step of an inner wall of the pre-combustor housing  22 . the locations of the first contact surface  223  and the second contact surface  224  substantially limit a height of the plunger air pump cavity  301 . 
     Referring to  FIG.  2    together, In an embodiment, the plunger air pump assembly  30  includes a fuel supply pipeline assembly, and the fuel supply pipeline assembly is communicated with an engine and the plunger air pump cavity  301 . The fuel supply pipeline assembly includes a plunger air pump pipeline intake pipe  41 , an air compression device  42 , a gasification mixing device  43  and a plunger air pump intake pipe  35 . An inlet end of the plunger air pump pipeline intake pipe  41  is arranged between an engine air filter  51  and an engine intake pipe  52  (the figure is only schematic). The air compression device  42  and the gasification mixing device  43  are communicated with the plunger air pump pipeline intake pipe  41  through pipelines, and the fuel supply pipeline assembly is communicated with the plunger air pump cavity  301  through the plunger air pump intake pipe  35 . The plunger air pump intake pipe  35  is communicated with an outlet end of the plunger air pump pipeline intake pipe  41 . In this embodiment, the inlet end of the plunger air pump pipeline air intake pipe  41 , that is, an air intake position, is arranged behind the engine air filter, in order to prevent the fresh air entering the plunger air pump cavity  301  from being affected by the EGR. The air compression device  42  may be an electric plunger pump or a Roots pump, because it requires a small air volume and has a low compression ratio. The electric pump is flexible in control and convenient in arrangement, and a crankshaft-driven mechanical pump may also be selected if required. A fuel supply method of the gasification mixing device  43  is may be a Port Fuel Injection (PFI) electronically controlled fuel injector, because of its flexible and accurate fuel quantity control, simple structure and high reliability. A carburetor fuel supply may also be selected if required. The internal mixing device may be a filled steel ball mixing, because this method has a simple structure and high reliability. A mesh mixing may also be selected. A heating method of the gasification mixing device  43  may be an electric heating method, because this device can speed up fuel consumption during cold start, and increase the temperature of the mixed fuel, thereby reducing the difficulty of cold start. If required, other heating methods are used without arranging electric heating related devices according to the actual practical environment. A compression ratio of the air compression device  42  in this embodiment is in a range of 1.5-2.5. An excess air coefficient of the mixed fuel prepared by the gasification mixing device  43  is in a range of 0.6-2.2. 
     Referring to  FIG.  3    and  FIG.  4   , when the fuel supply system for the active pre-combustor of the present application operates, an upward direction and a downward direction of the plunger air pump rod  32  and the piston  13  are opposite, and the plunger air pump rod  32  always moves in an opposite direction to the piston  13 . In an engine compression stage, the piston  13  goes up, and the plunger air pump rod  32  goes down. In an engine intake stage, the piston  13  goes down, and the plunger air pump rod  32  goes up. In a power stroke and exhaust stroke in the engine, the plunger air pump rod  32  is kept stationary or moves in an opposite direction of piston  13  in the main combustor  16  according to practical design requirements. The fresh air flowing into the fuel supply pipeline assembly is firstly pre-pressurized by the air compression device  42  at a constant pressure ratio, and then the fuel and the fresh air are fully mixed by the gasification mixing device  43  according to the required air-fuel ratio. The mixed fuel is finally delivered into the plunger air pump cavity  301  through the plunger air pump intake pipe  35 . If the fuel supply system for the active pre-combustor of the present application is used for a vehicle gasoline engine, a diameter of the plunger air pump cavity  301  is in the range of 1-40 mm, and a stroke of the plunger air pump rod  32  is in the range of 1-40 mm. If it is used for a diesel engine, the diameter of the plunger air pump cavity  301  is in a range of 5-500 mm, and the stroke of the plunger air pump rod  32  is in a range of 10-500 mm. 
     Referring to  FIG.  3   , when the plunger air pump rod  32  is at a top dead center, the piston  13  is at the lowest point, the plunger air pump pipeline intake pipe  41  is communicated with the pre-combustor cavity  221  through the plunger air pump cavity  301 . The mixed fuel mixed by the air compression device  42  and the gasification mixing device  43  can enter the plunger air pump cavity  301  and the pre-combustor cavity  221  through the plunger air pump intake pipe  35 . 
     When the plunger air pump driver  31  drives the plunger air pump rod  32  to go down gradually, the mixed fuel circulates in the plunger air pump cavity  301  and the pre-combustor cavity  221 , and is also gradually pressed into the pre-combustor cavity  221  simultaneously. The mixed fuel in the pre-combustor cavity  221  is pressurized and heated. 
     Referring to  FIG.  4   , when the plunger air pump rod  32  goes down to a bottom dead center, the piston  13  is at the highest point, and the plunger air pump rod  32  contacts the second contact surface  224  on the pre-combustor housing  22 . The plunger air pump piston  34  separates the plunger air pump cavity  301  from the pre-combustor cavity  221 , to prevent a backflow of the mixed fuel in the pre-combustor. In this circumstance, the mixed fuel in the pre-combustor cavity  221  is ignited, and the temperature and the pressure in the pre-combustor increase. The high-temperature mixture in the pre-combustor is sprayed to the main combustor  16  at a high speed through the pre-combustor injection holes  222 , and rapidly ignites mixed fuel in the main combustor  16 . 
     In the fuel supply system for the active pre-combustor of the present application, a plunger air pump assembly is added to the pre-combustor assembly to deliver mixed fuel to the pre-combustor based on a reciprocating stroke opposite to a piston, which is safe, reliable and efficient. The mixed fuel in the pre-combustor is mixed by a pre-mixing method, making it easier to ensure an equivalence ratio at an ignition position of the pre-combustor, while also avoiding coking and soot formation caused by the excessively rich mixture, and a misfire caused by lean mixture at ignition position. The mixed fuel is prepared outside the pre-combustor, which realizes a partial decoupling of the pre-combustor gas components and the main combustor gas components, thereby solving the problem of the misfire caused by an excessive proportion of residual exhaust gas in a condition of high EGR rate. In addition, since the high-pressure mixed fuel in the present application is prepared when it is in need. On the one hand, the high-pressure gas storage device is omitted, the cost is reduced, and the risk of leakage of the high-pressure mixed fuel is reduced. On the other hand, since the temperature of the mixed fuel is increased after compression, the ignition stability is improved and the difficulty of cold start is also reduced. 
     Described above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that any person skilled in the art can easily think of within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.