Patent Application
20110239991
The present disclosure relates to engine fuel systems, and more specifically to fuel injectors.
This section provides background information related to the present disclosure which is not necessarily prior art.
A fuel injector may include a pressurized fuel supply used to open and close an injection nozzle opening. The injector may include an actuation member and a valve mechanism to selectively open and close a leakage path between low pressure and high pressure regions of the injector. Opening the leakage path may reduce a closing biasing force applied to an injection valve to open the injection nozzle opening. When the leakage path is closed, the injection valve may be displaced to close the injection nozzle opening. Thus, the injection nozzle opening is typically in one of two positions, i.e., a closed position or an open position, depending on whether pressurized fuel is being provided to the injection nozzle opening.
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A fuel injector may include a housing, a poppet valve assembly, and an actuation assembly. The housing may define a longitudinal bore, a high pressure fuel duct in communication with the longitudinal bore and a valve seat including a valve seat surface and an aperture. The valve seat surface may be in communication with the high pressure fuel duct. The aperture may extend through the valve seat surface and be in communication with the longitudinal bore. The high pressure fuel duct may carry pressurized fuel. The poppet valve assembly may include a stem and a valve head. The poppet valve assembly may be disposed within the longitudinal bore and be variably displaceable between a first position and a second position. In the first position, the valve head may abut the valve seat to seal the aperture. In the second position, the valve head may be displaced from the valve seat to open the aperture. The poppet valve assembly may be biased to be in the first position by the pressurized fuel. The actuation assembly may be coupled with the poppet valve assembly and operate to move the poppet valve assembly between the first position and the second position.
An engine assembly may include an engine structure defining a cylinder and a fuel injector supported by the engine structure and in communication with the cylinder. The fuel injector may include a housing, a poppet valve assembly, and an actuation assembly. The housing may define a longitudinal bore, a high pressure fuel duct in communication with the longitudinal bore and a valve seat including a valve seat surface and an aperture. The valve seat surface may be in communication with the high pressure fuel duct. The aperture may extend through the valve seat surface and be in communication with the longitudinal bore. The high pressure fuel duct may carry pressurized fuel. The poppet valve assembly may include a stem and a valve head. The poppet valve assembly may be disposed within the longitudinal bore and be variably displaceable between a first position and a second position. In the first position, the valve head may abut the valve seat to seal the aperture. In the second position, the valve head may be displaced from the valve seat to open the aperture. The poppet valve assembly may be biased to be in the first position by the pressurized fuel. The actuation assembly may be coupled with the poppet valve assembly and operate to move the poppet valve assembly between the first position and the second position.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
Examples of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
When an element or layer is referred to as being “on,” “engaged to,” “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Referring to
The fuel system 14 may include a fuel pump 22, a fuel tank 24, a fuel rail 26, fuel injectors 28, a main fuel supply line 30, secondary fuel supply lines 32 and fuel return lines 34. The fuel pump 22 may be in communication with the fuel tank 24 and may provide a pressurized fuel supply to the fuel rail 26 via the main fuel supply line 30. The fuel rail 26 may provide the pressurized fuel to injectors 28 via the secondary fuel supply lines 32. The fuel rail 26 may include a pressure regulating valve 36 that regulates fuel pressure within the fuel rail 26 by returning excess fuel to the fuel tank 24 via a return line 38.
The fuel injectors 28 may each include an actuation assembly 40 in communication with the control module 16. In the present non-limiting example, the fuel injectors 28 may form direct injection fuel injectors where fuel is injected directly into the cylinders 20. The fuel injectors 28 may return excess fuel to the fuel tank 24 via the fuel return lines 34.
Referring to
Fuel injector 28 may include a poppet valve assembly 60 disposed within the longitudinal bore 52. The poppet valve assembly 60 may include a stem 62 and a valve head 64. In a first position of the poppet valve assembly 60, i.e., the closed position, the valve head 64 may abut the valve seat 56 to seal the aperture 56A. In a second position of the poppet valve assembly 60, i.e., the fully opened position, the valve head 64 may open the aperture 56A to the maximum extent allowed to spray pressurized fuel into the cylinder 20 in which the fuel injector 28 is inserted. The poppet valve assembly 60 may be variably displaceable such that the valve head 64 may be moved to a plurality of positions between the first (closed) position and the second (fully opened) position. In this manner, the poppet valve assembly 60 may vary the size of the valve opening 65, which provides a variable amount of fuel and/or fuel flow rate to the cylinder 20.
The poppet valve assembly 60 may further include a piston 66 coupled to the stem 62. The piston 66 may be directly coupled to the stem 62 or, alternatively, the piston 66 may be coupled to the stem 62 indirectly, i.e., through the use of an auxiliary component or components. In one non-limiting example, the piston 66 may be coupled to the stem 62 through interaction with projections 67 coupled to the stem 62 (see
Pressurized fuel may be provided to the longitudinal bore 52 of the fuel injector 28 through the high pressure fuel duct 54. The pressurized fuel may bias the poppet valve assembly 60 to be in the first (closed) position. The valve head 64 may define a valve head surface area 63 that contacts the pressurized fuel in the first (closed) position. Similarly, the piston 66 may define a piston surface area 69 that contacts the pressurized fuel. In one exemplary embodiment, the piston surface area 69 is greater than the valve head surface area 63 such that the pressurized fuel biases the poppet valve assembly 60 to be in the first (closed) position. In another exemplary embodiment, the piston surface area 69 is equal to the valve head surface area 63 such that the pressurized fuel in combination with the biasing member 68 biases the poppet valve assembly 60 to be in the first (closed) position. Furthermore, the biasing member 68 may also bias the poppet valve assembly 60 to be in the first (closed) position. The biasing member 68 may thus seal the aperture 56A in a situation where fuel is not being provided at a sufficient pressure to the fuel injector 28 (such as when the engine assembly 10 is off).
The poppet valve assembly 60 may be moved between the first (closed) position and the second (fully opened) position by an actuation assembly 40 coupled thereto. The actuation assembly 40 may be any variable position actuator, for example, a piezoelectric actuator, an electromagnetic actuator, a magnetostrictive actuator, a servo actuator or a solenoid actuator. In a non-limiting example, the actuation assembly 40 is coupled to the stem 62 and operates to move the valve head 64 between the first (closed) position and second (fully opened) position. As discussed above, the actuation assembly 40 may operate to move the poppet valve assembly 60 to a plurality of positions between the first (closed) position and the second (fully opened) position such that the size of the valve opening 65 will vary, thus providing a variable amount of fuel and/or fuel flow rate to the cylinder 20.
The housing 50 may further define a low pressure fuel duct 58. The low pressure fuel duct 58 may be in communication within the longitudinal bore 52. The piston 66 may be disposed between the high pressure fuel duct 54 and the low pressure fuel duct 58. During operation of the fuel injector 28, pressurized fuel may travel around the piston 66 from the high pressure fuel duct 54 to the low pressure fuel duct 58. The clearance between piston 66 and longitudinal bore 52 may be as low as practical (for example, between 0.1 and 5 microns) in order to minimize fuel flow between the high pressure fuel duct 54 to the low pressure fuel duct 58, while still permitting movement of the poppet valve assembly 60 between the first (closed) position and second (fully opened) position. The low pressure fuel duct 58 may be in communication with the fuel return lines 34 such that excess fuel may be returned to the fuel tank 24, as discussed above.
Referring to
In a second example (
In a third example (
