Patent Application
20120103308
This disclosure relates generally to fuel injection systems, and in particular to a two-way valve orifice plate having a raised valve seat configured to facilitate fluid drainage.
Internal combustion engines using injectors associated with each cylinder are known. A typical fuel injector includes various valves and valve arrangements operating to inject fuel into the cylinder in a controlled fashion. These valves are controlled, typically, by electronic actuators associated with each fuel injector. Each fuel injector is capable of injecting a quantity of fuel into a cylinder of an internal combustion engine at pre-determined times and for pre-determined durations. A typical injector is positioned beneath the valve cover of the engine and in direct fluid communication with the cylinder. During operation, electrical signals sent to the fuel injector actuate a valve that injects fuel into the cylinder.
Common rail fuel systems typically employ multiple fuel injectors to inject high-pressure fuel into the combustion chambers of an engine. Each of these fuel injectors may include a nozzle assembly having a cylindrical bore with a nozzle supply passageway and a nozzle outlet. A needle check valve may be reciprocatingly disposed within the cylindrical bore and biased toward a closed position where the nozzle outlet is blocked. In response to a deliberate injection request, the needle check valve may be selectively moved to open the nozzle outlet, thereby allowing high-pressure fuel to flow from the nozzle supply passageway into the combustion chamber.
Typically, a spring biases the needle of the injector toward a closed position. Periodically, an actuator actuates to move the needle or to otherwise allow the needle to move to an open or injection position to dispense a predetermined amount of fuel into the combustion chamber. In one type of fuel injector, high-pressure fuel is pumped into the injection chamber from a high-pressure fuel source, such as a common rail, with the fluid creating a force tending to lift the needle against the force of the spring. To prevent the needle from moving, high-pressure fuel is also provided to a pressure balancing reservoir disposed at an end of the needle opposite the injection orifices to balance the force applied by the high-pressure fuel in the injection chamber. At the appropriate time, an actuator mechanism opens a valve to drain the high-pressure fuel from the pressure balancing reservoir and allow the needle to move to the open position and inject fuel into the combustion chamber.
One example of this type of fuel injector is provided in U.S. Pat. No. 5,803,369, issued Sep. 8, 1998. High-pressure fuel is present in a pressure control chamber, with a solenoid valve lifting a spherical member off of an annular seat face of a flat plate to release the pressure in the pressure control chamber. The high-pressure fuel flows from the pressure control chamber through a restrictor hole through the flat plate, over the annular seat face and into an annular groove passage, and outwardly through radial fuel groove passages. With the pressure released, a nozzle needle may move upwardly so that the high-pressure fuel is discharged through close injection holes. In the embodiment shown in
In one aspect, the invention is directed to a pressure balancing orifice plate for a fuel injector device. The orifice plate may include a cylindrical body having a top surface, a bottom surface, an annular outer surface, and a body longitudinal axis, a balance pressure relief orifice extending from the top surface to the bottom surface, and a raised valve seat extending upwardly from the top surface and surrounding the balance pressure relief orifice. The valve seat may have a central seat surface encircling the balance pressure relief orifice and a plurality of leaf portions extending radially outwardly from the central seat surface and defining drainage channels there between. A width WC of the drainage channels may increase as the radial distance from the balance pressure relief orifice increases.
In another aspect, the invention is directed to a fuel injector the may include a check needle for controlling flow of fuel into a combustion chamber, a pressure balancing reservoir having pressurized fuel therein that urges the check needle toward a closed fuel blocking position, and a control valve assembly. The control valve assembly may include a pressure balancing orifice plate that may have a balance pressure relief orifice extending from a top surface to a bottom surface of the pressure balancing orifice plate, and may have a raised valve seat extending upwardly from the top surface and surrounding the balance pressure relief orifice. The balance pressure relief orifice may be in fluid communication with the pressure balancing reservoir, and the raised valve seat may have a central seat surface encircling the balance pressure relief orifice and a plurality of leaf portions extending radially outwardly from the central seat surface and defining drainage channels there between. The control valve assembly may further include a valve member that may have a planar surface configured to engage the raised valve seat and form a seal there between to prevent fluid flow through the balance pressure relief orifice. The valve member may selectively control a flow of pressurized fuel from the pressure balancing reservoir to a drain so that the pressurized fuel maintains the check needle in the closed fuel blocking position when the valve member forms the seal between the valve member and the valve seat. The pressurized fuel may drain through the balance pressure relief orifice to allow the check needle to move to an open fuel injection position when the valve member is disengaged from the valve seat.
In a further aspect, the invention is directed to a fuel injector system for use in an internal combustion engine. The fuel injector system may include a high-pressure fuel source, an injection chamber in fluid communication with the high-pressure fuel source, a check needle for controlling flow of pressurized fuel from the injection chamber into a combustion chamber, a pressure balancing reservoir in fluid communication with the high-pressure fuel source, wherein pressurized fuel therein urges the check needle toward a closed fuel blocking position, and a control valve assembly. The control valve assembly may include a pressure balancing orifice plate that may have a balance pressure relief orifice extending from a top surface to a bottom surface of the pressure balancing orifice plate, and may have a raised valve seat extending upwardly from the top surface and surrounding the balance pressure relief orifice. The balance pressure relief orifice may be in fluid communication with the pressure balancing reservoir, and the raised valve seat may have a central seat surface encircling the balance pressure relief orifice and a plurality of leaf portions extending radially outwardly from the central seat surface and defining drainage channels there between. The control valve assembly may further include a valve member that may have a planar surface configured to engage the raised valve seat and form a seal there between to prevent the pressurized fuel from flowing through the balance pressure relief orifice. The valve member may selectively control flow of pressurized fuel from the pressure balancing reservoir to a drain so that the pressurized fuel maintains the check needle in the closed fuel blocking position when the valve member forms the seal between the valve member and the valve seat, and the pressurized fuel may drain through the balance pressure relief orifice to allow the check needle to move to an open fuel injection position when the valve member is disengaged from the valve seat.
Additional aspects of the invention are defined by the claims of this patent.
Although the following text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims defining the invention.
It should also be understood that, unless a term is expressly defined in this patent using the sentence “As used herein, the term ‘______’ is hereby defined to mean . . . ” or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims). To the extent that any term recited in the claims at the end of this patent is referred to in this patent in a manner consistent with a single meaning, that is done for sake of clarity only so as to not confuse the reader, and it is not intended that such claim term be limited, by implication or otherwise, to that single meaning. Finally, unless a claim element is defined by reciting the word “means” and a function without the recital of any structure, it is not intended that the scope of any claim element be interpreted based on the application of 35 U.S.C. §112, sixth paragraph.
Within the nozzle case 22, a check sleeve 30 may be disposed and further define the injection chamber 20. The check sleeve 30 may extend between the check guide plate 28 and a check lift spacer 32, with the check lift spacer 32 engaging a nozzle tip 34 extending out of a nozzle opening 36 of the nozzle case 22. When the fuel injector 10 is assembled, the entire stack composed of the orifice plate 26, the check guide plate 28, the check sleeve 30, the check lift spacer 32 and the nozzle tip 34 may be together into sealing engagement to form seals preventing leakage of the high-pressure fuel from the fuel injector 10 when the valve body 24 is attached to the nozzle case 22. The check guide plate 28, check sleeve 30, check lift spacer 32 and nozzle tip 34 may have axial bores 40-46 in which a check valve stem 38 is disposed.
The axial bore 40 of the check guide plate 28 may have an inner diameter slightly larger than an outer diameter of an upper portion of the check valve stem 38 such that the upper portion fits snuggly within the axial bore 40 and is guide by the axial bore 40 so that check valve stem 38 may move up and down axially within the injection chamber 20. In contrast, the axial bores 42, 44 of the check sleeve 30 and check lift spacer 32, respectively, may have larger inner diameters than an outer diameter of a central portion of the check valve stem 38 so that the injection chamber 20 has the necessary volume for high-pressure fuel for the proper operation of the fuel injector 10. The axial bore 46 of the nozzle tip 34 may have a smaller inner diameter than the axial bores 42, 44, but still provide an annular space between the axial bore 46 and a needle 48 of the check valve stem 38 disposed therein to allow high-pressure fuel to flow to injection orifices 50 of the nozzle tip 34. The tip of the needle 48 and end of the nozzle tip 34 may be configured to form a seal when the needle 48 engages the end of the nozzle tip 34 to prevent fuel flow through the injection orifices 50. Upward movement of the check valve stem 38 disengages the needle 48 from the end of the nozzle tip 34 to allow fuel to be injected into the combustion chamber. An annular shoulder 52 of the needle 48 having an outer diameter slightly smaller than the inner diameter of the axial bore 46 aligns the needle 48 within the nozzle tip 34 while allowing fuel to flow to the injection orifices 50, perhaps with the aid of grooves, orifices or other flow channels formed therein.
The central portion of the check valve stem 38 disposed within the check sleeve 30 includes an upper annular shoulder 54 having an outer diameter smaller than the inner diameter of the axial bore 42 to allow the flow of fuel through the injection chamber 20. A spring 56 disposed between the annular shoulder 54 and the bottom surface of the check guide plate 28 provides a force biasing the check valve stem 38 toward the nozzle tip 34 so that the needle 48 forms the seal preventing fuel from exiting the injection orifices 50. If necessary, a spacer 58 having an appropriate thickness may be placed between the spring 56 and the upper surface of the annular shoulder 54 to control the compression of the spring 56.
To keep the check valve stem 38 seated until the appropriate time to inject the fuel into the combustion chamber, a pressure balancing reservoir 60 that will be charged with the pressurized fuel is provided at the upper end of the axial bore 40 of the check guide plate 28. Referring to
At the same time high-pressure fuel is provided to the injection chamber 20, the pressure balancing reservoir 60 is pressurized with the high-pressure fuel. While the check valve stem 38 is seated and the pressure balancing reservoir 60 is pressurized as shown in
The pressurized fuel is drained from the pressure balancing reservoir 60 via a balance pressure relief orifice 66 through the orifice plate 26. The drainage of fuel through the balance pressure relief orifice 66 is controlled by a two-way solenoid valve 68 that operates to cause a spherical member or ball 70 to alternately engage a valve seat of the orifice plate 26 to prevent fluid flow and disengage from the valve seat to allow drainage. As seen in greater detail in
Returning to
During normal operation of the fuel injector 10, the solenoid valve 68 is actuated and de-actuated at a high frequency such that heat is generated within the valve body 24 by the electric current in the solenoid 86 and the reciprocating motion of the armature 76 and armature pin 72. To regulate the temperature within the valve body 24, coolant may be provided at a coolant inlet 88. The coolant inlet 88 is placed in fluid communication with the axial bore 74 of the valve body 24 by a low-pressure fluid passage 90. Once in the axial bore 74, the coolant circulates around, among other components, the armature pin 72, armature 76, armature housing 78, spring 80, collar 82 and spacer 84 to draw heat from the components. After absorbing heat, the coolant exits the axial bore 74 via a second low-pressure fluid passage 92 to a drain reservoir 94 in the nozzle case 22 before flowing out of the fuel injector 10 through drain orifices 96.
The drain reservoir 94 also provides an outlet for the high-pressure fuel released through the balance pressure relief orifice 66 when the ball 70 is unseated. Referring back to
The raised valve seat 102 surrounding the balance pressure relief orifice 66 may have a central seat surface 110 with a plurality of leaf portions 112 extending outwardly there from. The central seat surface 110 may include a hole 114 coaxial with the balance pressure relief orifice 66 and may have a larger diameter than the inner diameter of the balance pressure relief orifice 66 such that the hole 114 may appear to be counter bored or countersunk. The increased diameter of the hole 114 may allow implementation of the orifice plate 26 in fuel injectors 10 with balance pressure relief orifices 66 of differing sizes up to the diameter of the hole 114 without affecting the performance of the solenoid valve 68 by providing a constant surface area upon which the high-pressure fuel acts. The leaf portions 112 extend outwardly from the central seat surface 110, and have widths WL that may be relatively narrow proximate the central seat surface 110 and increase as the radial distance from the central seat surface 110 increases. The leaf portions 112 extend for a distance from the central seat surface 110, but terminate along the top surface 100 inward of the annular outer surface 98.
The intersection of the central seat surface 110 and adjacent leaf portions 112 may have a radius of curvature R defining a curved surface there between so that a generally continuous, uninterrupted edge may be formed around the perimeter of the valve seat 102. The spaces between adjacent leaf portions 112 may form drainage channels 116 extending outwardly from the central seat surface 110. When the ball 70 is unseated, the high-pressure fuel from the pressure balancing reservoir 60 may flow over the central seat surface 110, down into the drainage channels 116, over the top surface 100 and off the outer edge of the orifice plate 26 into the drain reservoir 94. In the illustrated embodiment, the leaf portions 112 may be dimensioned such that the width WC of the drainage channels 116 increases as the radial distance from the central seat surface 110 increases. Increasing the width of the drainage channels 116 correspondingly increases the volume of the drainage channels 116 so that the velocity of the draining fuel decreases as it flows outwardly from the balance pressure relief orifice 66.
As discussed above, the valve body seat 104 encircles the high-pressure fuel passage 16 and the balance pressure orifice 64. By providing a continuous raised surface between the high-pressure fuel passage 16 and the balance pressure orifice 64, the valve body seat 104 and high-pressure fuel balancing passage 62 form a closed channel placing the high-pressure fuel passages 14, 16 in fluid communication with the balance pressure orifice 64 when the valve body 24 and orifice plate 26 are aligned and in contact with each other. As with the valve seat 102 and balance pressure relief orifice 66, the valve body seat 104 may include a hole 118 coaxial with balance pressure orifice 64 and having a larger diameter than the inner diameter of the balance pressure orifice 64.
In the embodiment shown in
As a further example,
The foregoing invention finds utility in various industrial applications, such as in internal combustion engines where fuel injectors are actuated for hundreds or thousands of cycles per second. In such environments, the space allocated for the fuel injectors may be limited, and it may be desirable to operate efficiently in terms of the size of the components of the fuel injector and the amount of energy required to operate the fuel injector. The useful life of the fuel injector is also important, as the engines within which the fuel injectors are installed are expected to operate for thousands of hours with minimal maintenance.
In the present design, the configuration of the valve seats 102, 130 and the ball 70 allow the sizes of the solenoid valve 68 and corresponding spring 80 to be minimized while still providing a sufficient seal when the seating portion 70b of the ball 70 engages the valve seat 102, 130. The design also facilitates drainage of the pressurized fuel with creating undesirable cavitation. The spring 80 must provide sufficient force to hold the ball 70 tightly seated against the valve seat 102, 130 when high-pressure fuel is provided to the pressure balancing reservoir 60. The amount of force required to hold the ball 70 in place against the high-pressure fuel is determined by the pressure of the fuel in the pressure balancing reservoir 60 and the diameter of the hole 114, and the sealing pressure applied by the spring 80 at the valve seat 102, 130 is determined by the size of the surface contact area between the seating portion 70b and the valve seat 102, 130. The amount of pressure applied to the contact area is inversely proportional to the size of the contact area. Consequently, the same spring force applies greater pressure to a smaller contact area, thereby forming a tighter seal to prevent leakage from the pressure balancing reservoir 60.
In view of this, the central seat surface 110 and the leaf portions 112 in accordance with the present disclosure may be dimensioned to reduce to the contact area with the planar seating portion 70b of the ball 70, and correspondingly reduce the size of the spring 80 required to seat the ball 70 and the size of the solenoid 86 required to unseat the ball 70 against the force of the spring 80. In one exemplary implementation, the fuel injector 10 may have a maximum operating pressure of approximately 250 MPa (approx. 36.3 kpsi), while the hole 114 at the surface of the valve seat 102, 130 may have an inner diameter of approximately 0.45 mm (approx. 0.018 in.). When the ball 70 is seated and the pressure balancing reservoir 60 is pressurized at the maximum operating pressure, the pressurized fuel acts on an area of approximately 0.16 mm2 (approx. 0.0002 sq in.), resulting in an upward force of approximately 40 N (approx. 9.0 lb. force) being exerted on the ball 70 by the high-pressure fuel. A spring force greater than 40 N (9.0 lb. force) must be applied by the spring 80 to overcome the fluid pressure and seat the ball 70, but a substantially greater force should be used to prevent leakage. Consequently, the spring 80 may be selected to apply an assembled load of approximately 125 N (approx. 28.1 lb. force).
The diameter DS of the planar seating portion 70b of the ball 70 may be approximately 2.0 mm (approx. 0.079 in.), while the diameter of the central seat surface 110 may be considerably smaller with a value of approximately 0.8 mm (approx. 0.031 in.). The balance pressure relief orifice 66 may have a diameter in the range of 0.2-0.3 mm (0.008-0.012 in.) Consequently, when the ball 70 is seated and the contact area between the planar seating portion 70b and the central seat surface 110 is approximately 0.34 mm2 (approx. 0.0005 sq in.). Additional contact area is added by the leaf portions 112, but the amount is minimized by having the width WL minimized proximate the central seat surface 110 as shown in the drawings. The width WL may range from a minimum of approximately 0.30 mm (approx. 0.012 in.) proximate the central seat surface 110 to approximately 0.51 mm (approx. 0.020 in.) at a distance of approximately 1.0 mm (approx. 0.039 in.) from the center of the balance pressure relief orifice 66, which approximately coincides with the distance to the outer edge of the planar seating portion 70b of the ball 70. The dimensions provide a contact area between the planar seating portion 70b and the valve seat 102, 130 of approximately 1.138 mm2 (approx. 0.0018 sq in.). With a spring force of 125 N (28.1 lb. force), the spring 80 provides a sealing pressure of approximately 110 MPa (approx. 16.0 kpsi) to make a substantially leak-proof seal when the ball 70 is seated. A larger contact area would require a correspondingly larger spring force to achieve the same sealing pressure. With the pressurized fluid generating an approximately 40 N (approx. 9.0 lb. force) force, and the spring 80 providing an approximately 125 N (approx. 28.1 lb. force) force, the solenoid 86 must generate an upward force of greater than 85 N (19.1 lb. force) to overcome the spring force and unseat the ball 70.
Those skilled in the art will understand that foregoing is one example of an implementation of an orifice plate 26 in accordance with the present disclosure, and application of such orifice plates 26 in fuel injectors 10 having differing dimensions and operating pressures are contemplated by the inventors. Moreover, other configurations of the orifice plate 26 are contemplated. For example, in some implementations, the high-pressure fuel passage 18 and/or the balance pressure orifice 64 may be provided in components other than the orifice plate 26 while still placing the pressure balancing reservoir 60 in fluid communication with the high-pressure fuel inlet 12. In such implementations, the valve body seat 104 or valve body seat portion 134 may be reconfigured or eliminated due to the absence of one or both of the high-pressure fuel passage 18 and balance pressure orifice 64.
While the preceding text sets forth a detailed description of numerous different embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fail within the scope of the claims defining the invention.
