Patent Application
20240295206
The present disclosure relates generally to a boot in a fuel system, and more particularly to a boot having standoff protrusions to maintain an air gap between a fuel injector and an inner boot surface.
The fuel system in a modern internal combustion engine is often the most complex and expensive part of the equipment. Fuel is typically pressurized to a range of pressures depending upon application and injection location, and delivered for combustion in one or more shots of fuel into a cylinder by way of precisely controlling electrically and/or hydraulically actuated components in fuel injectors. Pressurized fuel systems can require specialized sealing and fuel containment apparatus. For regulatory and other purposes higher pressure portions of a fuel system often employ double-walled containment, such that in the event of a liquid fuel and/or fuel vapor leak fuel is contained in a secondary system outside of the highly pressurized portions and can be returned to a fuel tank or otherwise safely handled.
A component known as a boot is sometimes used in pressurized fuel systems and can assist in positioning and/or protecting certain components, including fuel injectors and fuel connections. An example boot employed in a fuel system is known from co-pending application Ser. No. 17/895,564, filed Aug. 25, 2022, to Wiebrecht. While the designs proposed in Wiebrecht offer promise, there is always room for improvement and development of alternative strategies.
In one aspect, a fuel system includes a fuel injector including an injector housing having a fuel inlet and a fuel outlet formed therein, and an electrical connector projecting from the injector housing. The fuel system further includes a fuel conduit connected to the fuel injector, and a boot. The boot includes an elongate boot body defining a longitudinal axis and having an inner boot surface extending circumferentially around the longitudinal axis and forming a central cavity extending between an injector portion of the elongate boot body receiving the fuel injector, and a conduit portion of the elongate boot body receiving the fuel conduit. The injector portion includes a window formed at least partially therein receiving the electrical connector and a plurality of radially inward standoff protrusions in contact with the fuel injector so as to maintain an air gap between the fuel injector and the inner boot surface.
In another aspect, a boot assembly for a fluid system includes a fuel injector including an injector housing having a fuel inlet and a fuel outlet formed therein, and an electrical connector projecting from the injector housing. The boot assembly further includes a boot including an elongate boot body defining a longitudinal axis and having an inner boot surface extending circumferentially around the longitudinal axis and forming a central cavity extending between an injector portion of the elongate boot body receiving the fuel injector, and a conduit portion of the elongate boot body. The elongate boot body further includes a window formed at least in part in the injector portion and receiving the electrical connector, and a plurality of radially inward standoff protrusions in contact with the fuel injector so as to maintain an air gap between the fuel injector and the inner boot surface.
In still another aspect, a boot for a fuel injector and conduit assembly in a fuel system includes an elongate boot body defining a longitudinal axis and including an injector portion, a conduit portion, an outer boot surface, and an inner boot surface extending circumferentially around the longitudinal axis and forming a central cavity extending from an open first axial end formed in the injector portion to an open second axial end formed in the conduit portion. The elongate boot body further includes a plurality of standoff protrusions within the injector section. The plurality of standoff protrusions project radially inward from the inner boot surface and define a circle centered on the longitudinal axis so as to support a fuel injector within the injector portion at an air gap clearance from the inner boot surface.
Referring to
Cylinder head 12 further includes one or more intake ports 20 formed therein. In a practical implementation engine system 10 is port-injected with liquid methanol fuel. The methanol fuel may be ignited by way of a compression-ignited direct injection of a diesel distillate fuel or ignited via dimethyl ether, for example. As will be further apparent from the following description engine system 10 is uniquely configured by way of fuel system apparatus for containment of liquid fuel and fuel vapors as well as ventilation of fuel supply and containment apparatus. While aspects of the present disclosure are described in the context of a fuel system, in other instances teachings herein could be applied in a different type of fluid system, such as system supplying and delivering oil in an engine or other machinery context, or still other environments.
To this end, engine system 10 further includes a fuel system 22. Fuel system 22 includes a fuel injector and conduit assembly 24. Referring also now to
Fuel system 22 and assembly 24 further include a fuel conduit 36 connected to fuel injector 26. Fuel conduit 36 may include a double-walled fuel conduit having an outer wall 38 and an inner wall 40 defining a fuel supply passage 42 fluidly connected to fuel inlet 30, and also to a fuel pressurization pump and a liquid fuel supply such as a methanol fuel tank (not shown). An interwall space 44 typically having the form of an annulus is defined between outer wall 38 and inner wall 40. In a practical implementation strategy, a vacuum is drawn on interwall space 44 such that a negative pressure is continuously applied. In the event of fuel leakage the negative pressure can assist in ensuring that any leaked liquid fuel and/or vapors can be returned to a fuel tank, for example, or safely discharged to ambient. Inner wall 40 may further include an injector fitting 46 coupled to and in contact with a body portion 52 of fuel injector 26. A tip portion 54 of fuel injector 26 projects from body portion 52. An O-ring 58 may be provided to seal between injector fitting 46 and body portion 52.
Fuel system 22 further includes a boot 60 in a boot assembly 62. Boot 60 includes an elongate boot body 64 defining a longitudinal axis 66. Boot body 64, referred to herein at times interchangeably with boot 60, includes an inner boot surface 68 extending circumferentially around longitudinal axis 66 and forming a central cavity 70 extending between an injector portion 72 of boot body 64 receiving fuel injector 26, and a conduit portion 74. Conduit portion 74 of boot body 64 receives fuel conduit 36. Injector portion 72 includes a window 76 formed at least partially therein and receiving electrical connector 34. Injector portion 72 also includes a plurality of radially inward standoff protrusions 78 in contact with fuel injector 26 so as to maintain an air gap 80 between a fuel injector 26 and inner boot surface 68. During service a vacuum may be pulled on interwall space 44 to draw air into central cavity 70 through window 76 or another opening in boot body 64. Based on the vacuum, or other factors, in some instances, inner boot surface 64 could collapse in contact with fuel injector 26 preventing or reducing the potential for air flow through air gap 80. Standoff protrusions 78 can reduce or eliminate such tendency to collapse. Boot body 64 may be formed of a deformable, non-metallic material such as natural rubber or a suitable natural or synthetic rubber-like material including any of a variety of different polymeric materials readily commercially available. Fuel conduit 36 may be formed of a suitable metallic material such as steel.
Radially inward standoff protrusions 78 may be spaced apart in at least one of a circumferential aspect or an axial aspect, and project radially inward from inner boot surface 68. In an embodiment, radially inward standoff protrusions 78 are spaced apart in the at least one of a circumferential aspect or an axial aspect in a regular pattern. An irregular distribution is nevertheless within the scope of the present disclosure. Embodiments are also contemplated wherein standoff protrusions 78 have the form of spiraling protrusions providing a generally axial flow path. Referring also now to
As can be further noted from the drawings, boot body 64 includes an outer boot surface 69, and window 76 communicates between outer boot surface 69 and inner boot surface 68. Central cavity 70 extends from an open first axial end 94 formed in injector portion 72 to an open second axial end 96 formed in conduit portion 74. Standoff protrusions 78 may be confined in distribution to injector portion 72, although the present disclosure is not thereby limited.
Referring now to
Returning focus to
Referring to the drawings generally, during service valve assembly 50 can be energized to inject a fuel via fuel injector 26 into intake port 20 for combustion in a cylinder in engine system 10. A vacuum is pulled on conduit 36, providing negative pressure in interwall space 44. The negative pressure can cause a flow of air to pass through boot assembly 62 and draw liquid fuel or fuel vapors leaked from fuel injector and/or conduit assembly 24 back to a fuel tank or other vessel for containment, or potentially for safe discharge to ambient. Radially inward standoff protrusions as discussed herein assist in preventing collapse of boot 60 against fuel injector 26.
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 stated otherwise.
