Valve assembly

Although modern diesel fuel formulations are intended to reduce emissions of diesel engines, at least some of those modern fuels tend to have relatively low lubricity levels. The control valve assemblies described herein help to minimize any increased wear that would otherwise result from the use of such low lubricity fuels by providing a valve element, a valve guide, and an insert. The valve element is received within the valve guide and is moveable between an open position and a closed position. The insert forms a first sealed interface and a second sealed interface with the valve element and the valve guide. When the valve element is in the closed position, both of the first sealed interface and the second sealed interface are engaged. When the valve element is in the open position, only one of the first sealed interface and the second sealed interface is engaged.

TECHNICAL FIELD

The present disclosure relates to high-pressure pumps. More particularly, the present disclosure relates to valve assemblies for use in high-pressure pumps.

BACKGROUND

Emissions regulations in the United States, Europe, Japan, China and other countries are becoming increasingly stringent in terms of the emissions levels that are permitted for diesel engines. For example, the U.S. regulations limit, among other things, the levels of particular matter and oxides of nitrogen (commonly referred to a NOx) that may be emitted from a diesel engine. In addition to the regulations governing diesel engine emissions, the U.S. government has also promulgated regulations requiring the sulfur content of highway diesel fuel to be below a certain level (e.g., 15 ppm). This too has been done in an effort to facilitate the reduction of the particulate matter emitted by diesel engines.

Although reducing the sulfur content of diesel fuel helps to reduce undesirable emissions, this often has the effect of reducing the lubrication levels of the fuel. The processing steps that are used to produce the standard U.S. low sulfur diesel fuel, or ultra low sulfur diesel fuel as it is often called, generally result in a reduction in the average normal carbon chain length, which also tends to reduce the lubrication levels of the fuel. Fuel blenders sometimes compensate for the reduced lubricity, at least in part, through the use of additive packages, but this generally does not result in the desired lubrication levels. Other specialty fuels, such as Toyu and JP8, also feature shorter than average normal carbon chain lengths and lower sulfur than traditional U.S. 2D diesel fuel, and therefore also possess relatively low lubrication levels.

One area in which the reduced lubricity of diesel fuel has a significant impact is the fuel system of diesel engines, particularly the pumps and injectors of the fuel system. Pumps and injectors include key parts that move or reciprocate relative to other parts millions of times during the life of an engine. When the fuel serves as a lubricant to these parts, which is often the case, a reduction in the lubricity of the fuel can significantly increase the rate of wear in these parts, which in turn leads to earlier failure of the parts and/or the entire fuel system. For example, conventional inline plunger or piston fuel pumps that are used to generate the high fuel pressure in common rail fuel systems may include control valve assemblies that actuate millions of times during the life of the pump. Although these control valve assemblies may experience little wear over time when used with pump traditional 2D diesel fuel, their use with newer diesel fuel formulations that have reduced lubricity may cause these control valve assemblies to prematurely fail due to the increase in wear experienced by the control valve assemblies when used with these newer fuels.

Although certain materials may be selected that would exhibit a resistance to wear in the presence of a fluid with low lubricity levels, the use of these materials in a fuel systems application is often very difficult. For example, a ceramic material may provide acceptable resistance to wear in the presence of a fuel with low lubrication levels. However, the incorporation of a ceramic material into a fuel system is made difficult due to the fact that ceramics tend to be very hard, making the manufacture of ceramic parts more difficult, they tend to be expensive, making extensive use of the material cost prohibitive, and their brittle nature makes them susceptible to failure when subjected to tensile stresses, which are difficult to avoid in fuel systems applications. Also making the selection of an appropriate material difficult is the corrosive nature of many diesel fuels. Materials that would otherwise possess favorable characteristics may not be suitable for use in a fuel system because of their susceptibility to corrosive attack by the diesel fuel.

Various efforts have been made to address wear issues in high-pressure pumps. One example of such an effort is described in U.S. Pat. No. 6,019,125, issued Feb. 1, 2000 (“the '125 patent”). The '125 patent discloses a valve that fits within a cylindrical cavity formed in the pump body and that is retained in position by an overlying retention plug. The valve includes a cage-shaped valve body that includes an upper part and a lower part. The upper part includes four ribs, while the lower part includes a valve seat. The valve also includes a valving element located within the valve body that is guided by the four ribs and that is maintained in the closure position by a spring. Although the valve disclosed in the '125 patent appears to have been designed with wear in mind, it appears to have been designed not to minimize wear but rather to be easily replaceable after excessive wear occurs. Moreover, the '125 patent fails to appreciate the different wear characteristics that may result from the use of different fuel compositions, such as the different wear characteristics that may result from the use of traditional U.S. 2D diesel fuel versus the new U.S. ultra low sulfur diesel fuel.

It would be advantageous to provide a relatively simple, reliable, durable, and inexpensive control valve assembly that could effectively operate in a fuel system in which low lubricity diesel fuels are used.

SUMMARY

According to one exemplary embodiment, a control valve assembly for a high-pressure pump comprises an actuator, a valve element, a valve guide, and an insert. The actuator is moveable in response to an input signal. The valve element is coupled to the actuator and is moveable between an open position and a closed position. The valve element includes a body and a head. The body includes a first guide surface and the head includes a first sealing surface. The valve guide includes a guide bore, an end, and a flow passage between the guide bore and the end. The guide bore receives the body of the valve element, the end includes a second sealing surface, and the flow passage is configured to allow fluid to flow through the valve guide. The insert is coupled to one of the valve member and the valve body and includes a third sealing surface and a fourth sealing surface. The third sealing surface cooperates with the first sealing surface of the valve element to form a first sealed interface. The fourth sealing surface cooperates with the second sealing surface of the valve guide to form a second sealed interface. The movement of the actuator causes the valve element to move between the closed position, in which both of the first sealed interface and the second sealed interface are engaged, and the open position, in which one of the first sealed interface and the second sealed interface is engaged and the other one of the first sealed interface and the second sealed interface is disengaged.

According to another exemplary embodiment, a method of selectively coupling a pumping chamber with a fluid source comprises the step of providing a flow chamber between a valve guide and a valve element. The flow chamber is fluidly coupled to the fluid source and the valve element is selectively moveable relative to the valve guide. The method also comprises the steps of selectively moving the valve element toward the valve guide to a closed position in which the flow chamber is fluidly disconnected with the pumping chamber and selectively moving the valve element toward the pumping chamber to an open position in which the flow chamber is fluidly coupled to the pumping chamber. The method also comprises the step of sealing the flow chamber by compressing an insert between the valve guide and the valve element when the valve element is in the closed position.

DETAILED DESCRIPTION

Referring generally toFIG. 1, a fuel system10is shown according to one exemplary embodiment. Fuel system10is the system of components that cooperate to deliver fuel (e.g., diesel, gasoline, heavy fuel, etc.) from a location where fuel is stored to the combustion chamber(s) of an engine12where it will combust and where the energy released by the combustion process will be captured by engine12and used to generate a mechanical source of power. Although depicted inFIG. 1as a fuel system for a diesel engine, fuel system10may be the fuel system of any type of engine (e.g., internal combustion engine such as a diesel or gasoline engine, a turbine, etc.). According to one exemplary embodiment, fuel system10includes a tank14, a transfer pump16, a high-pressure pump18, a common rail20, fuel injectors22, and an electronic control module (ECM)24.

Tank14is a storage container that stores the fuel that fuel system10will deliver. Transfer pump16pumps fuel from tank14and delivers it at a generally low pressure to high-pressure pump18. High-pressure pump18, in turn, pressurizes the fuel to a high pressure and delivers the fuel to common rail20. Common rail20, which is intended to be maintained at the high pressure generated by high-pressure pump18, serves as the source of high-pressure fuel for each of fuel injectors22. Fuel injectors22are located within engine12in a position that enables fuel injectors22to inject high-pressure fuel into the combustion chambers of engine12(or pre-chamber or ports upstream of the combustion chamber in some cases) and generally serve as metering devices that control when fuel is injected into the combustion chamber, how much fuel is injected, and the manner in which the fuel is injected (e.g., the angle of the injected fuel, the spray pattern, etc.). Each fuel injector22is continuously fed fuel from common rail20such that any fuel injected by a fuel injector22is quickly replaced by additional fuel supplied by common rail20. ECM24is a control module that receives multiple input signals from sensors associated with various systems of engine12(including fuel system10) and indicative of the operating conditions of those various systems (e.g., common rail fuel pressure, fuel temperature, throttle position, engine speed, etc.). ECM24uses those inputs to control, among other engine components, the operation of high-pressure pump18and each of fuel injectors22. The purpose of fuel system10is to ensure that the fuel is constantly being fed to engine12in the appropriate amounts, at the right times, and in the right manner to support the operation of engine12.

Referring now toFIG. 2, high-pressure pump18is configured to increase the pressure of the fuel from a pressure that is sufficient to transfer the fuel from the tank to a pressure that is desirable for the injection of the fuel into the combustion chambers of engine12(or injection elsewhere). Such injection pressures may vary between different applications, but often range between approximately 1500 bar and 2000 bar, and may include pressures that are below 1500 bar or above 2000 bar. According to one exemplary embodiment, pump18includes a housing30, a head32, a camshaft34, two tappet assemblies36, two resilient members40, two plunger assemblies43, and two control valve assemblies42.

Housing30is a rigid structure that generally serves as the base of pump18. Housing30includes a central bore44that is configured to receive camshaft34, as well as two spaced-apart, parallel tappet bores46that are each configured to receive at least a portion of a tappet assembly36, a plunger assembly43, a resilient member40, and head32. The axis of each tappet bore46is arranged perpendicularly (or radially) to the axis of central bore44such that the rotation of camshaft34within central bore44causes tappet assemblies36to translate in a linear, reciprocating manner within tappet bores46. Near the distal ends of tappet bores46, housing30also includes a face48that is configured to receive head32.

Head32is coupled to face48of housing30and generally serves, among other things, to enclose tappet bores46, provide a portion of the structure defining pumping chambers86(discussed below), receive control valve assemblies42, and provide various ports and ducts to direct the flow of fuel into and out of pumping chambers86. Head32includes a face50that cooperates with face48of housing30(and a sealing element such as an o-ring) to provide a sealed interface between head32and housing30. As illustrated inFIG. 3, head32also includes two apertures54, each of which is configured to receive a portion of control valve assembly42and a portion of plunger assembly43. Each aperture54includes four regions, region72, region74, region76, and region88, which have progressively smaller diameters as the aperture extends into head32. Regions72,74, and76are configured to receive portions of control valve assembly42, while region78is configured to receive a portion of plunger assembly43. Region74includes an engagement structure79shown as threads that are configured to engage a corresponding engagement structure of a portion of control valve assembly42.

Camshaft34is a driven member that is formed from an elongated shaft that includes two sets of cam lobes56that are spaced apart along the length of camshaft34and a gear or pulley57on one of its two ends. Gear or pulley57is a driven member that is configured to engage another member, such as another gear, a chain, or a belt, that is driven, either directly or indirectly, by engine12. The two sets of cam lobes56are spaced apart along the length of camshaft34so as to correspond with each of the two tappet assemblies36. According to various exemplary and alternative embodiments, each set of cam lobes56may include a single cam lobe, two cam lobes, three cam lobes, or more than three cam lobes, with each cam lobe representing a complete pumping and filling cycle. According to other various alternative and exemplary embodiments, the two sets of cam lobes may be in phase with one another (such that the cam lobes of the first cam lobe set will pass under head32at the same time as the corresponding cam lobes of the second cam lobe set) or they may be out of phase with one another (such that the cam lobes of the first cam lobe set will pass under head32at different times than the corresponding cam lobes of the second cam lobe set). According to other various alternative and exemplary embodiments, the extent to which the cam lobes of the first cam lobe set may be out of phase relative to the cam lobes of the second cam lobe set may vary depending on the application of pump18and other factors.

Referring still toFIG. 2, each tappet assembly36(also sometimes referred to as a lifter assembly) is configured to engage one of the two sets of cam lobes56, transform the rotational movement of the corresponding cam lobes56into linear movement, and transfer such linear movement to the corresponding plunger assembly43. Each tappet assembly36includes a body58that engages and receives a portion of plunger assembly43, a roller60that engages and follows a set of cam lobes56, and a pin62that couples roller60to body58. Body58is received within the corresponding tappet bore46of housing30and translates back and forth within tappet bore46as camshaft34rotates.

Resilient member40, shown as a compression spring, is an element or member that serves to bias the corresponding plunger assembly43and tappet assembly36toward camshaft34. By biasing both the corresponding plunger assembly43and tappet assembly36toward camshaft34, resilient member40helps to ensure that plunger assembly43returns to its lowest position (hereinafter referred to as “bottom dead center”) before camshaft34completes another rotation (or partial rotation, depending on the cam lobe configuration) and forces plunger assembly43back up to its highest position (hereinafter referred to as “top dead center”). This helps to ensure that plunger assembly43is performing a complete filling cycle (the cycle where plunger assembly43moves from top dead center to bottom dead center) and a complete pumping cycle (the cycle where plunger assembly43moves from bottom dead center to top dead center) for each cam lobe56in the corresponding cam lobe set of camshaft34.

Plunger assembly43is an assembly of components that is located generally between the corresponding tappet assembly36and head32and that reciprocate with tappet assembly36relative to head32to pressurize the fluid within pumping chamber86. According to one exemplary embodiment, plunger assembly43includes a plunger80and a retainer82. Plunger80is a member (e.g., piston, shaft, rod, element, retained member) that is configured to reciprocate or slide within region78of aperture54of head32as the corresponding tappet assembly36reciprocates within tappet bore46of housing30. According to one exemplary embodiment, plunger80includes an elongated, generally cylindrical body83having a side wall87, a first end89that is configured to extend into region78of aperture54, and a second end91located near tappet assembly36. First end89, region78of aperture54, and a portion of control valve assembly42define pumping chamber86, the volume of which changes as plunger80moves back and forth, or up and down, within region78of aperture54. Retainer82is a component or an assembly of components that couple to plunger80and that serve to apply at least a portion of the force provided by resilient member40to plunger80. Retainer82is an element or assembly of elements that serves to receive resilient element40(e.g., spring) and ultimately transfer the force provided by resilient element40to plunger80.

Referring now toFIGS. 2 and 3, each control valve assembly42generally serves to control the fluid communication between pumping chamber86(discussed below) and the fuel being provided by transfer pump16, and therefore is capable of controlling the amount of fuel that enters pumping chamber86during the filling cycle and the amount of fuel that remains in pumping chamber86during the pumping cycle. According to a first exemplary embodiment, control valve assembly42includes a valve element63, an actuator71, a valve guide68, a connector69, and an insert70.

Valve element63is moveable between on open position in which a fuel inlet passage84is fluidly connected to pumping chamber86and a closed position in which fuel inlet passage84is not fluidly connected to, or is sealed off from, pumping chamber86. According to one exemplary embodiment, valve element63extends through regions72,74, and76of aperture54and includes a body88, an armature interface90, a stem92, and a head94. Body88is a generally cylindrical portion of valve element63and defines a guide surface96that cooperates with valve guide68to guide the movement of valve element63relative to valve guide68. Armature interface90extends from one end of body88and receives a portion of actuator71(e.g., armature64and sleeve75, described below). Armature interface90may be threaded to facilitate the coupling of armature64and/or or sleeve65to valve element63, or armature interface90may be configured in any one of a variety of different ways to facilitate the engagement of armature64and sleeve65with valve element63. For example armature interface90may be configured so that either or both of armature64and sleeve65freely slide over armature interface90, may be press fit onto armature interface90, or engage armature interface90in any one of a variety of other ways. A shoulder98is formed where armature interface90extends from body88and serves to provide a positive stop for armature64and to help align armature64. Stem92extends from the opposite end of body88and has a diameter that is less than that of body88. The reduced diameter of stem92, in combination with a portion of valve guide68, insert70, and head94, defines a chamber100(e.g., a flow chamber) that enables fluid to flow between valve element63and valve guide68when valve element63is in the open position. Head94is coupled to the distal end of stem92and forms a cap-like structure having a diameter that is larger than the diameter of stem92and body88. Head94includes a sealing surface102that extends perpendicularly and radially outward from the distal end of stem92and that is configured to engage a corresponding sealing surface on insert70when valve element63is in the closed position to substantially seal off pumping chamber86from inlet passage84. According to various alternative and exemplary embodiments, valve element63may take one of a variety of different configurations. For example, the relative sizes of the different portions of valve element63may vary depending on the application (e.g., the diameter of the head may be the same size as or smaller than the diameter of the body, the diameter of the stem may be the same size as the diameter of the body, etc.), the orientation of the sealing surface may vary (e.g., it may be substantially perpendicular to a longitudinal axis of the valve element, or it may be oriented at an acute or obtuse angle relative to the longitudinal axis), and/or the shape or configuration of the sealing surface may vary (e.g., it may be flat, it may form a knife edge, it may be curved, it may have one or more flat, curved, and/or pointed portions, etc.).

Actuator71is an electronically controlled device that generates movement in response to an electric signal. Within control valve assembly42, actuator71serves to move valve element63relative to valve guide68. According to one exemplary embodiment, actuator71includes an armature64, a sleeve65, a biasing member66, and a solenoid67. Armature64is a disk-like element that includes an aperture that receives armature interface90of valve element63. A sleeve or retainer shown as sleeve65may be provided to secure armature64to valve element63. For example, sleeve65may include a threaded interface that engages a threaded interface provided on armature interface90of valve element63. Armature64may then be secured to valve element63by tightening sleeve65onto armature interface90and forcing armature64against shoulder98of valve element63. Solenoid67is coupled to the top of head32such that a portion of valve element63extends through an aperture104extending at least partially through solenoid67. Biasing member66, shown as a compression spring, is located within aperture104and receives a portion of valve element63and sleeve65. In addition to helping to secure armature64to valve element63, sleeve65may also facilitate the application of force by the spring66to armature64and valve element63.

According to one exemplary embodiment, solenoid67is a device that includes a coil of wires wrapped around a core that together create a magnetic field when an electrical current is passed through the wires. Solenoid67is configured so that armature64is drawn toward solenoid67when the magnetic field is created. Solenoid67and armature64may be configured so that there is relatively little or no attraction of armature64to solenoid67when no electrical current is being passed through solenoid67. Spring66helps to ensure that armature64returns to a position away from solenoid67when the flow of current through solenoid67is terminated. Spring66is configured to provide a biasing force that is sufficient to force armature64away from solenoid67when solenoid67is deactivated but which may be overcome when solenoid67is activated. Because armature64is coupled to valve element63, the movement of armature64is transferred to valve element63. Thus, when solenoid67is activated, armature64moves toward solenoid67causing valve element63to move to the closed position. When solenoid67is deactivated, armature64is pushed away from solenoid67by spring66causing valve element63to move to the open position. According to an alternative embodiment, the solenoid, armature, and spring may be arranged so that activation of the solenoid moves the valve element to the open position while deactivation of the solenoid allows the spring to move the valve element to the closed position. According to other alternative and exemplary embodiments, the actuator may be replaced by any suitable actuation device that controls the movement of the valve element relative to the valve guide. For example, another actuation device or configuration that may be used may include a piezo controlled actuation system, a hydraulically controlled actuation system, or any other suitable actuation system.

Valve guide68is an element or member that forms the structure within which valve element63slides and is guided and with which valve element63engages to seal pumping chamber86from inlet passage84. According to one exemplary embodiment, valve guide68includes a first end106located proximate armature64, a second opposite end108located proximate head94of valve element63, an aperture110extending longitudinally through valve guide68, a recess111in end108, a recess112around the outer periphery of valve guide68, and flow passages114. Aperture110extends between first end106and second end108and includes a first region116that is configured to closely receive body88of valve element63and a second region118that defines, in combination with stem92, insert70, and head94of valve element63, chamber100. First region116is intended to serve as a guide within which guide surface96of valve element63may slide. To minimize any fluid leakage that may occur between the surface defining first region116and body88, the gap between them may be minimized. Second region118has a diameter larger than that of first region to help form chamber100. In order to allow fluid to pass from inlet passage84into chamber100, from which it will then be able to enter pumping chamber86, flow passages114are provided through the portion of valve guide68defining second region118. Recess111, which is configured to receive insert70, is provided in end108and is defined by a generally radial surface113and by a generally axial surface115. Recess112is provided around the outer periphery of approximately the top half of valve guide68and is configured to receive connector69. Recess112forms a radially outwardly extending shoulder120that is engaged by a portion of connector69to enable connector69to apply a force to valve guide68that urges valve guide68toward a sealing surface122within head32that is located between regions74and76of aperture54. According to various alternative and exemplary embodiments, the valve guide may take one of a variety of different shapes and configurations. For example, according to one alternative embodiment, the diameter of the second region of the aperture may be the same as, or smaller than, the diameter of the first region. According to another alternative embodiment, the second end of the valve guide may include a structure different than, or in addition to, a recess in order to receive the insert.

Connector69(e.g., nut, plug, fastener, stopper, retainer, etc.) is a structure that serves to couple valve guide68to head32, to align or properly position valve guide68within aperture54of head32, and to apply a force to valve guide68sufficient to create a seal between valve guide68and sealing surface122of head32(either directly or indirectly). According to one exemplary embodiment, connector69includes a head124, an engagement structure126, and an aperture128that extends longitudinally through connector69. Head124is a radially enlarged portion of connector69that is shaped (e.g., hex shaped) to facilitate the application of a torque to connector69. The radial enlargement of connector69may also serve as a positive stop that limits the extent to which connector69may be threaded into region74of aperture54by engaging a surface130on head32located between regions72and74of aperture54. Engagement structure126, shown as threads, is configured to engage the corresponding engagement structure79provided on head32to allow connector69to be securely coupled to head32and to allow connector69to provide an adequate force to valve guide68to create a seal between end108of valve guide68, insert70, and surface122of head32. Aperture128defines a region132that slides over or receives the portion of valve guide68defined by recess112. Aperture128also defines a shoulder134that engages shoulder120of valve guide68to apply a linear force to valve guide68that urges valve guide68towards surface122of head32. According to various alternative and exemplary embodiments, the connector may take any one of a variety of different configurations that enable it to retain the valve guide within the head in the appropriate position and in the appropriate manner.

Referring still toFIGS. 2 and 3, insert70(e.g., seal structure, valve seat, seal, gasket, etc.) is an element or member formed from a wear resistant material that is located in a position in which it forms a seating or contact surface that repeatedly engages, or is repeatedly engaged by, another element having a corresponding seating or contact surface. According to one exemplary embodiment, insert70is a ring-shaped member that is received within recess111in end108of valve guide68. Insert70has a generally rectangular cross section and includes an inner surface136, and outer surface137, a valve face138, and a guide face139. When received within recess111, outer surface137generally abuts axial surface115of recess111, guide face139generally abuts radial surface113of recess, inner surface136has approximately the same diameter as second region118of aperture110of valve guide68and forms a portion of chamber100, and valve face138faces head94of valve element63. The diameter of inner surface136is smaller than the diameter of head94of valve element63, while the diameter of outer surface137is larger than the diameter of region76of aperture54in head32. This allows valve face138of insert70to engage both head94of valve element63and sealing surface122of head32. Outer surface137is also longer than axial surface115of recess111, therefore providing a portion of insert70that extends out of recess111. This allows insert70to be held in place (at least in part) by being pinched or compressed between valve guide68(which is urged toward sealing surface122by the force applied to it by connector69) and sealing surface122of head32. As used herein, the terms “compress,” “compressed,” or “compression” should not be read to imply or require a change in shape or reduction in volume on the part of the member being compressed, although such a change in shape or reduction in volume may occur. The coupling of insert70within recess111of valve guide68forms a sealed interface between guide face139of insert70and radial surface113of recess111that is intended to prevent, or substantially prevent, the flow of fluid between valve guide68and insert70. Because insert70is compressed between valve guide68and a portion of head32, the sealed interface between guide face139of insert70and radial surface113of recess111remains engaged as valve element63moves between the open and closed positions. The coupling of insert70between valve guide68and sealing surface122of head32also forms a sealed interface between valve face138of insert70and sealing surface122of head32that is intended to prevent, or substantially prevent, the flow of fluid between insert70and sealing surface122. When valve element63is moved into the closed position where insert70is compressed between head94and end108of valve guide68, sealing surface102of head94is moved into contact with valve face138of insert70and creates a sealed interface that is intended to prevent, or substantially prevent, the flow of fluid between insert70and head94of valve element63. When valve element63is moved into the open position, sealing surface102of head94is moved away from valve face138of insert70, which then allows for the flow of fluid between insert70and head94. Thus, the sealed interface between sealing surface102of head94and valve face138of insert70is engaged when valve element63is in the closed position and disengaged when valve element63is in the open position.

According to various alternative and exemplary embodiments, the insert may be made from any one or more of a variety of different materials that may be suitable for a particular application, and the materials may be provided in any number of different configurations. For example, the insert may be formed from a single material or it may be formed from a substrate over which an appropriate coating is applied. According to one exemplary embodiment, insert70may be intended for use with potentially corrosive fuels having low sulfur content and/or an average carbon chain lengths less than that of traditional 2D diesel fuels. Such fuels may include the ultra-low sulfur diesel fuel currently required in the U.S., JP8, K1, Toyu, Howell A, and other similar fuels, either alone or in conjunction with various fuel additives such as, for example, Caterpillar 2564968 fuel additive, methyl soyate (10-30% by volume), rapeseed methyl ester, reclaimed cooking oil, etc. In such an application and environment, insert70may be selected from one of a variety of different materials and take one of a variety of different configurations. For example, insert70may be made from a metal such as 440C stainless steel. Alternatively, insert70may be made from a metal substrate and coated with a material selected from various metal nitrides and diamond like carbons (DLC). For example, potentially suitable metal nitrides may include chromium nitride, zirconium nitride, molybdenum nitride, titanium-carbon-nitride, or zirconium-carbon-nitride, and suitable diamond-like carbon materials may include titanium containing diamond-like carbon (DLC), tungsten-DLC, or chromium-DLC. Alternatively, insert70may be made from a cermet, such as, for example, tungsten carbide in cobalt matrix, etc. Alternatively, insert70may be made from a ceramic, such as, for example, silicon carbide, zirconia, etc. Alternatively, insert70may be made from any one or more of the materials identified above. In any case, the appropriate material or materials from which the insert should be made will depend in large part on the application in which the control valve assembly will be used and on the characteristics of the fluid with which the control valve assembly will be used. Thus, an insert constructed from a certain material may be suitable for one application but not necessarily a different application.

According to various alternative and exemplary embodiments, instead of, or in addition to, being compressed between the valve guide and a portion of the head, the insert and valve guide may be configured so that the insert is retained within the recess in the valve guide through a press fit, an adhesive may be applied to the insert to help retain it with the recess, or other well know methods and/or components may be used to help retain the insert within the recess in the valve guide.

Referring now toFIG. 4, a second exemplary embodiment of the control valve assembly is shown. This second exemplary embodiment, control valve assembly142, is substantially similar to control valve42, the primary difference being that the insert is coupled to the valve element rather than the valve guide. Instead of remaining stationary when the valve element moves back and forth, as is the case with control valve assembly42, the insert of control valve assembly142moves back and forth along with the valve element. Thus, with control valve42, a moving head94seats against a stationary insert70, whereas with control valve assembly142, a moving insert seats against a stationary valve guide.

Control valve assembly142is arranged similarly to control valve assembly42and shares substantially similar components. To avoid unnecessary duplication, control valve assembly142will be described based primarily on how it differs from control valve assembly42. Similar to control valve assembly42, control valve assembly142includes a valve guide168having an end208, a valve element163, and an insert170. However, unlike valve guide68, end208of valve guide168does not include a recess configured to receive insert170, which then engages sealing surface122of head32. Instead, end208of valve guide168is configured to directly engage sealing surface122to create a sealed interface that is intended to prevent, or substantially prevent, the flow of fluid between them. Rather than being coupled to the valve guide, insert170is coupled to valve element163. Valve element163is configured to receive insert170such that a valve face238of insert170abuts against a sealing surface202of a head194of valve element163. In this configuration, the movement of valve element163between the closed position and the open position causes insert170to repeatedly contact (and form a sealed interface with) end208of valve guide168. The coupling of insert170to valve element163forms a sealed interface between valve face238of insert170and sealing surface202on head194of valve element163that is intended to prevent, or substantially prevent, the flow of fluid between valve element163and insert170. Because insert170is coupled to valve element163, the sealed interface between valve face238of insert170and sealing surface202on head194of valve element163remains engaged as valve element163moves between the open and closed positions. When valve element163is moved into the closed position where insert170is compressed between head194and end208of valve guide168, a guide face239of insert170is moved into contact with end208of valve guide168and creates a sealed interface that is intended to prevent, or substantially prevent, the flow of fluid between insert170and end208of valve guide168. When valve element163is moved into the open position, guide face239of insert170is moved away from end208of valve guide168, which then allows for the flow of fluid between insert170and end208. Thus, the sealed interface between guide face239of insert170and end208of valve guide168is engaged when valve element163is in the closed position and disengaged when valve element163is in the open position.

To receive insert170, valve element163is generally nail-shaped, having an elongated shaft of a first diameter and then a flange of a larger diameter forming head194. Insert170slides over the elongated shaft until it abuts sealing surface202of head194. A spacer or sleeve203may be provided that slides over the elongated shaft of valve element163and that extends between guide face239of insert170and the bottom of armature64. Sleeve203is configured such that when sleeve65is coupled to an armature interface190, sleeve65will sandwich or compress armature64, sleeve203and insert170between the bottom of sleeve65and sealing surface202on head194of valve element163. Thus, the presence of sleeve203will allow insert170to be retained in position by the threading of sleeve65onto armature interface190. According to other various alternative and exemplary embodiments, valve element163and sleeve203may be configured so that sleeve203threads onto valve element163to hold insert170against head194. According to other alternative and exemplary embodiments, insert170may be press fit onto valve element163, may be directly threaded onto valve element163, may be adhered to valve element163with an adhesive or epoxy, and/or may be coupled to valve element163in any other suitable manner.

According to various alternative and exemplary embodiments, the insert in either of the embodiments described above may take one of a variety of different configurations. For example, although the insert is illustrated as a ring having a generally rectangular cross-sectional shape, the cross-sectional shape of the insert may be square, trapezoidal, triangular, oval, circular, foot-ball shaped, or any other shape that is suitable for a particular application and the components with which the insert cooperates. According to other various alternative and exemplary embodiments, the insert may be coupled to a portion of head32or to another component of the control valve assembly, either in lieu of, or in addition to, coupling the insert to the valve element or valve guide. According to other various alternative and exemplary embodiments, the insert, valve guide, valve element, and/or pump head may be configured such that the insert is releasably coupled within the control valve assembly such that the insert may be removed from the control valve assembly and replaced with a new or different insert.

Although only one pump configuration was described above, it should be understood that the described pump is only one example of a pump in which the different embodiments of the control valve assembly may be used. For example, while only an inline plunger or piston pump was described above, the control valve assembly could also be used within any one of a variety of different piston or plunger pump configurations (e.g., axial piston pump, radial piston pump, bent axis pump, inlet metered pump, outlet metered pump, etc.) and with any one of a variety of different fluids (e.g., fuel, oil, hydraulic fluid, etc.). It also should be understood that while pump18was described above as including two cylinders or pumping chambers86, and consequently, two corresponding tappet assemblies36, resilient members40, control valve assemblies42, and plunger assemblies43, the pump could also be configured to include one, three, four, or more than four pumping chambers, depending on the particular application in which the pump is intended to be used.

Although only two different control valve assembly configurations were described above, it should be understood that the described control valve assembly configurations are only two examples of the many different valve configurations or systems in which the insert may be used or incorporated. For example, the insert may also be incorporated into the control valve assembly of a fuel injector, such as a common rail fuel injector. The insert may also be incorporated into a check valve or into other types of valves that have a seat and a moving element that repeatedly contacts the seat.

INDUSTRIAL APPLICABILITY

Pump18operates to pressurize a fluid (e.g., fuel) by drawing the fluid into one or more pumping chambers86, reducing the size of pumping chambers86, and then forcing the fluid through an outlet to common rail20. The way in which pump18operates will now be more specifically described in connection with one of pumping chambers86. Starting from the beginning of the pumping cycle, plunger80is at bottom dead center and pumping chamber86, which is normally full of fuel at this point, is at its maximum volume. As the peak of one of cam lobes56rotates to a position under tappet assembly36, the cam lobe56forces tappet assembly36, and therefore plunger assembly43, upward. As plunger assembly43moves upward (according to the shape or contour of cam lobe56), plunger80moves upward within region78of aperture54in head32thereby reducing the volume of pumping chamber86. Generally, at about the same time plunger80begins to move upward, solenoid67is energized, which has the effect of moving valve element63into the closed position where the pumping chamber86is closed off from fuel inlet passage84. The pressure within pumping chamber86also helps to urge valve element63into the closed position. As a result of the pressure within pumping chamber86, solenoid67may be deenergized during the pumping cycle without valve element63moving into the open position. As plunger80continues to move upward, the volume of pumping chamber86continues to reduce, which forces fuel out of pumping chamber86through a fuel outlet passage85and eventually to common rail20. The pumping cycle continues until plunger80reaches top dead center, which occurs when the peak of cam lobe56is below tappet assembly36. Generally, after plunger80reaches top dead center and begins the filling cycle, solenoid67is deenergized (if it wasn't already deenergized during the pumping cycle) and the pressure drops enough to allow valve element63to move, pursuant to the bias provided by spring66, to the open position where fuel from fuel inlet passage84is again permitted to enter pumping chamber86. As the peak of cam lobe56rotates past tappet assembly36, the bias provided by resilient element40urges plunger assembly43and tappet assembly36back down toward camshaft34. At this point, the backside of cam lobe56is below tappet assembly36, which allows it to move back down. As plunger80moves downward within aperture54during the filling cycle, fuel continues to fill pumping chamber86. When plunger80reaches bottom dead center, pumping chamber86will normally be full of fuel and at its maximum volume. The cycle then starts over again, with the cam lobe56urging tappet assembly36and plunger assembly43back up toward top dead center.

Control valve assembly42may be activated and deactivated at different times during the pumping and filling cycles to control how much fuel enters pumping chamber86during the filling cycle and/or to control whether pumping chamber86is coupled to fuel inlet passage84(which is part of a fluid circuit that flows back to transfer pump16and therefore acts as a drain) during all or a portion of the pumping cycle. In this way, the output of the pump may be controlled.

Depending on the configuration of the control valve assembly that is being used, each time the valve element is moved into the closed position, sealing surface102on head94of valve element63will make contact with or impact valve face139of insert70(with respect to control valve assembly42), or guide face239of insert170will make contact with or impact end208of valve guide168(with respect to control valve assembly142). The contact of sealing surface102with valve face139of insert70, in case of control valve assembly42, or the contact of guide face239of insert170with end208of valve guide168, in the case of control valve assembly142, is what creates a sealed interface that substantially prevents fluid communication between pumping chamber86and fuel inlet passage84.

Over the life of a pump similar to the one described above, the valve element will likely move between the open and closed positions millions of times. This means that a portion of the valve element will repeatedly make contact with or impact a corresponding sealing surface to create a temporary seal. The large number of contact or impact events combined with the lower lubricity of the newer blends of diesel fuel (e.g., U.S. ultra low sulfur diesel fuel, Toyu, JP8, etc.) makes avoiding excessive wear at or around the sealing surface or valve seats an increasingly difficult task.

Control valve assemblies42and142represent a reliable, low cost, and durable way to minimize the effects of wear at or around those sealing interfaces or valve seats that are repeatedly opened and closed. First, the use of insert70or170allows for the relatively isolated use of a material and/or coating strategy at or around the valve seat or sealing interface that, while suited for use at or around the valve seat, may not necessarily be suited for other components of control valve assembly42,142or head32. Second, the relatively small amount of material and/or coating used to form insert70,170makes it possible to utilize relatively expensive materials for insert70,170without adding much overall cost to control valve assembly42,142or pump18. Third, the manner in which insert70,170is incorporated into control valve assembly42,142(e.g., in general, between valve guide68,168and a portion of valve element63,163) creates a situation where the stresses to which insert70,170is exposed are primarily compressive forces. Consequently, brittle materials (e.g., ceramics, etc.) that generally are not capable of withstanding significant tensile stresses may be used in the construction of insert70,170. Thus, the manner in which insert70,170is incorporated into control valve assembly42,142creates a situation that permits the use of one or more of a wide range of materials. This helps to make the selection of an appropriate material, such as a material that is resistant to wear in the presence of low lubricity fuels and to the corrosive nature of such fuels, an easier task. Fourth, the relatively simple design of insert70,170does not require the use of complex machining. Thus, constructing insert70,170from materials that are difficult to machine (e.g., very hard and/or brittle materials) is not foreclosed because, in many cases, only a minimal amount of relatively simple machining will be required. Fifth, the use of insert70,170, which may be designed to be easily removed from control valve assembly42,142and replaced with a different insert, may allow a single control valve assembly42,142and/or pump18to be adapted to different working environments, such as an environment where the control valve assembly or pump will be exposed to a fuel or to another fluid having different characteristics. Thus, a pump originally configured for use with a certain fluid may be modified to work with a fluid having different properties by replacing the original inserts70,170of the pump with different inserts70,170, that are suited for use with the new fluid. Similarly, the use of insert70,170may make it possible to utilize a common control valve assembly configuration and common control valve assembly parts across different pump lines, except for insert70,170, which may be selected based on the particular application in which a pump line will be used.

It is important to note that the construction and arrangement of the elements of the control valve assembly as shown in the exemplary and other alternative embodiments is illustrative only. Although only a few embodiments of the control valve assembly have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements shown as multiple parts may be integrally formed, the operation of the interfaces (e.g., the interfaces between the valve guide, insert, valve element, head, etc.) may be reversed or otherwise varied, and/or the length or width of the structures and/or members or connectors or other elements of the assembly or system may be varied. It should be noted that the elements and/or assemblies of the control valve assembly may be constructed from any of a wide variety of materials that provide sufficient strength, durability, and other relevant characteristics, from any of a wide variety of different manufacturing processes, and in any of a wide variety of colors, textures, combinations, and configurations. It should also be noted that the control valve assembly may be used in association with various types of pumps, including a variety of different piston pumps, with a variety of different mechanisms in a variety of different applications (e.g., various mechanisms in engines, such as intake or exhaust valve actuation systems, fuel injectors, fuel transfer pumps, check valves, other various valves, etc.), and with a variety of different fluids (e.g., fuel, oil, hydraulic fluid, transmission fluid, water, coolant, etc.) Accordingly, all such modifications are intended to be included within the scope of the present disclosure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary and other alternative embodiments without departing from the spirit of the present disclosure.