The present disclosure relates generally to cooling internal components in a fuel injector, and more particularly to a cooling circuit in a fuel injector cooling actuator components with spent actuating fuel.
The fuel system in many modern internal combustion engine systems is one of the most complex, precise, and costly parts of the entire apparatus. Fuel injectors can include numerous components that are hydraulically or electrically actuated and travel very short travel distances at high speeds. Fuel injectors can be operated millions or even billions of cycles over the course of a service life, and fuel injector components can be subjected to mechanical wear and tear, contaminants, stress, strain, and harsh operating conditions. Many fuel injector components are machined to tight tolerances and undergo extensive testing and match-fitting with related parts prior to being placed in service.
Fuel injectors and fuel injector components can also experience relatively high absolute temperatures and pressures as well as swings in temperature or pressure during service. Internal combustion engines by definition generate heat and pressure during operation. Moreover, it is typically desirable to pressurize fuel for injection to relatively high injection pressures. Relatively highly pressurized fuel can also be quite hot. Thus, maintaining optimum service conditions for fuel systems has long been a challenge.
In some known fuel injection systems engine oil or another suitable fluid is used for fuel injector actuation, hydraulically moving internal fuel injector components such as control valves or injection valves or “checks.” In other fuel injection systems, fuel itself is used as an actuating fluid. In some systems, including so-called common rail fuel injection systems, highly pressured fuel is used both as the actuating fluid and for injection into cylinders to operate the engine. Common rail fuel systems can experience temperature and other service environment concerns that are even more significant than those associated with other fuel injection strategies. For these and other reasons various common rail and other high-pressure fuel systems can be highly sensitive to factors such as operating conditions and the presence of particulate debris. One known fuel system utilizing a common pressurized fuel reservoir is set forth in U.S. patent application Ser. No. 17/412,112, filed Aug. 25, 2021 to Bazyn et al.
In one aspect, a fuel injector assembly for a fuel-actuated fuel injector includes an injector body defining a longitudinal central axis extending between a first axial body end, and a second axial body end including a clamping face. The injector body has formed therein a high-pressure fuel passage extending from a high-pressure fuel inlet to the clamping face, and a valve pin bore extending axially from the clamping face to an armature cavity. The fuel injector assembly further includes an injection control valve assembly having an armature, an armature housing and a valve pin within the valve pin bore and extending through the armature and the armature housing. A low-pressure fuel passage is formed at least in part by the injector body and extends from the clamping face to the armature cavity to convey spent actuating fuel to the armature cavity. A flushing drain is formed by the injector body and fluidly connected to at least one of the valve pin bore or the armature cavity. The flushing drain forms, together with the low-pressure fuel passage and the armature cavity, a cooling circuit for the spent actuating fuel, and extends to a drain opening formed in an outer body surface of the injector body.
In another aspect, a fuel injector includes an injector housing having an injector body. The injector body has formed therein a high-pressure fuel passage, a drain opening, and a valve pin bore extending to an armature cavity. The injector housing further includes a nozzle piece having formed therein a plurality of spray orifices, and a valve seat plate clamped between the injector body and the nozzle piece and having formed therein each of a valve seat and a check control passage fluidly connected to the valve seat. The fuel injector further includes a nozzle check having a closing hydraulic surface exposed to a fluid pressure of a control chamber formed between the valve seat plate and the nozzle check and fluidly connected to each of the check control passage and the high-pressure fuel passage, and a cooling circuit including the armature cavity, a low-pressure fuel passage formed at least in part by the injector body, and a flushing drain formed by the injector body fluidly connected to at least one of the valve pin bore or the armature cavity and extending to the drain opening. The fuel injector further includes an injection control valve in contact with the valve seat and positioned fluidly between the check control passage and the low-pressure passage.
In still another aspect, a method of operating a fuel system for an internal combustion engine includes feeding a pressurized fuel from a pressurized fuel reservoir to a high-pressure inlet of a fuel injector in the fuel system, and energizing an electrical actuator to open an injection control valve such that a fuel pressure in a check control chamber in the fuel injector is reduced. The method further includes conveying spent actuating fuel expelled from the check control chamber through a low-pressure fuel passage extending to an armature cavity in the fuel injector, exchanging heat between the spent actuating fuel and components of the fuel injector exposed to the armature cavity, and flushing the spent actuating fuel from the armature cavity through a flushing drain fluidly connected between the armature cavity and a drain opening formed in an outer surface of the fuel injector.
Referring to
Engine system 10 also includes a fuel system 18. Fuel system 18 includes a fuel supply 20, a low-pressure transfer pump 22, a filter 24, and a high-pressure pump 26 structured to convey a pressurized fuel through a fuel supply conduit 29 to a pressurized fuel reservoir or common rail 28. A pressure sensor 30 is coupled to common rail 28 and in communication with an electronic control unit 32. Electronic control unit 32 can control high-pressure pump 24 including, for example, an inlet metered or an outlet metered pump, to maintain or adjust a pressure of pressurized fuel in common rail 28.
Common rail 28 fluidly connects to a plurality of fuel injector assemblies 34 in a plurality of fuel injectors 36. Each fuel injector 36 may extend partially into one of cylinders 14. A low-pressure return conduit 31 conveys low-pressure, spent actuating fuel from each of fuel injectors 36 back to fuel supply 20. Spent actuating fuel is fuel that has reduced in pressure after performing or contributing to actuation of a valve. Electronic control unit 32 may be electrically connected to a plurality of electrical actuators within fuel injectors 36 and operable to energize the electrical actuators in a generally known manner to operate injection control valves therein to control starting and ending of fuel injection. As will be further apparent from the following description each of fuel injectors 36 and fuel injector assemblies 34 may be uniquely configured by way of an internal cooling circuit to cool components of fuel injectors 36 exposed to an armature cavity using spent actuating fuel.
Referring also now to
A nozzle check 56 movable to open and close spray orifices 44 is within nozzle case 61 and nozzle piece 42 and includes a closing hydraulic surface 58 exposed to a fluid pressure of a control chamber 60. Control chamber 60 is formed between valve seat plate 52 and nozzle check 56 and fluidly connected to each of check control passage 55 and a high-pressure fuel passage 84 formed in injector body 40. An orifice plate 54 may be positioned between valve seat plate 52 and nozzle check 56 and includes a plurality of orifices therein (not numbered) that fluidly connect control chamber 60 to high-pressure fuel passage 84 and to check control passage 55 in a generally known manner. In other embodiments a combined valve seat plate and orifice plate in a single part could be used.
Focusing now on
Fuel injector assembly 34 and fuel injector 36 further include a low-pressure fuel passage 92 formed at least in part by injector body 40 and extending from clamping face 82 to armature cavity 90 to convey spent actuating fuel to armature cavity 90. Fuel injector assembly 34 and fuel injector 36 further include a flushing drain 94 formed by injector body 40 and fluidly connected to at least one of valve pin bore 88 or armature cavity 90. Flushing drain 94 forms, together with low-pressure fuel passage 92 and armature cavity 90, a cooling circuit 96 for the spent actuating fuel. Flushing drain 94 extends to a drain opening 98 formed in an outer body surface 99 of injector body 40.
In the embodiment of
Meanwhile the low-pressure, spent actuating fuel that is expelled past valve seat 53 can travel up through low-pressure fuel passage 92 and into armature cavity 90. Also in the illustrated embodiment low-pressure passage 92 includes an enlarged inlet portion 108 formed in clamping face 82. Enlarged inlet portion 108 may include a so called “bathtub” connector having the shape approximately of a bathtub that assists in permitting fuel to easily flow into low-pressure fuel passage 92. The fuel that is conveyed into armature cavity 90 can exchange heat with armature 64, armature housing 66, and other components of fuel injector 36 exposed to armature cavity 90. The spent actuating fuel having exchanged heat with components in armature cavity 90 can travel down through cooling circuit 96 through valve pin bore 88 and into flushing drain 94. The spent actuating fuel can thenceforth flow by way of drain outlet 98, and from like drain outlets in each of fuel injectors 36, into low-pressure return conduit 31.
Referring also to
Returning focus to
Referring now to
Turning now to
Referring to the drawings generally, it has been observed that pressurized fuel, and particularly pressurized fuel in common rail or similar fuel systems employing a common pressurized fuel reservoir can be relatively hot. Whereas certain earlier designs may convey some fuel into the vicinity of an armature or armature housing such earlier systems were often inadequate respecting cooling as no purging or outflow of the fuel occurred. When hot, still somewhat pressurized fuel is relatively quiescent deposits can form in or upon various fuel injector parts. Deposits can sometimes break apart and result in particles that can find their way between or among various moving parts or clearances in a fuel injector and cause performance degradation or even failure. Moreover, relatively large differences in temperature between parts due to insufficient cooling can cause other operating problems as certain components may grow or shrink differently than others. Such phenomena can also result in performance degradation or various other problems. According to the present disclosure spent actuating fuel, while relatively hot, can nevertheless significantly participate in exchanging heat with components in a fuel injector, particularly those in an injection control valve assembly and exposed to an armature cavity as discussed herein.
Operating fuel injectors and fuel systems according to the present disclosure can include feeding a pressurized fuel, such as a diesel distillate fuel, from a pressurized fuel reservoir to a high-pressure inlet of a fuel injector in the fuel system. An electrical actuator, such as a solenoid actuator as disclosed herein, can be energized to open an injection control valve such that a fuel pressure in a check control chamber in the fuel injector is reduced. As also discussed herein opening an injection control valve in this manner permits conveying spent actuating fuel expelled from the check control chamber through a low-pressure fuel passage extending to an armature cavity in the fuel injector.
It will be recalled a low-pressure fuel passage can be defined by an injector body, such as low-pressure fuel passage 92 defined by injector body 40. A low-pressure fuel passage may also be defined in part by an injector body and in part by a valve pin such as low-pressure fuel passages 192 and 292 in the embodiments of
The present description is for illustrative purposes only, and should not be construed to narrow the breadth of the present disclosure in any way. Thus, those skilled in the art will appreciate that various modifications might be made to the presently disclosed embodiments without departing from the full and fair scope and spirit of the present disclosure. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims. As used herein, the articles “a” and “an” are intended to include one or more items, and may be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has.” “have,” “having” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly staled otherwise.
Number | Name | Date | Kind |
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7021558 | Chenanda | Apr 2006 | B2 |
8635985 | Mcalister | Jan 2014 | B2 |
9341153 | Ibrahim | May 2016 | B2 |
9581120 | Morris | Feb 2017 | B2 |
20080295806 | Chang | Dec 2008 | A1 |
Number | Date | Country |
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2189648 | May 2010 | EP |
2008115738 | May 2008 | JP |
2014048605 | Apr 2014 | WO |
Entry |
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JP2008115738A (Kenji, D) (May 22, 2008) (Machine Translation) (Year: 2008). |
U.S. Appl. No. 17/412,112, filed Aug. 25, 2021 to Bazyn et al. |