Valve actuation assembly

A valve actuation assembly includes a housing and a vane connected to a shaft. The vane is at least partially disposed within the housing. The valve actuation assembly further includes a valve assembly connected to the housing and a feedback device connected to at least one of the vane and the shaft. The feedback device is configured to apply a feedback force to the valve assembly.

TECHNICAL FIELD

The present disclosure is directed to a valve actuation assembly and, more particularly, to a valve actuation assembly configured to control an exhaust gas recirculation (“EGR”) valve.

BACKGROUND

To minimize pollutants produced by internal combustion engines, a portion of the engine exhaust may be recirculated to an intake of the engine. An EGR valve, such as a mixing valve, may be used to assist in directing the portion of the exhaust to the intake. Such valves typically require a great deal of torque for actuation during engine operation. In addition, such valves are often disposed within the engine compartment and, thus, require compact actuation assemblies due to space constraints.

U.S. Pat. No. 3,948,231 issued to Smith (“the '231 patent”) discloses a power and deceleration governor for automotive engines including a butterfly-type mixture control valve. In a first embodiment, the valve is actuated using a rack and pinion assembly driven by a diaphragm motor. In a second embodiment, the valve is actuated using a hydraulic cylinder, and in a third embodiment, the valve is actuated using a clutch drive motor.

While the governors of the '231 patent may be configured to actuate the mixture control valve, each of the disclosed governors are relatively large and cumbersome, and may be difficult to package in a conventional engine compartment. In addition, each of the governors relies on a vacuum system for actuation. Such a system may not supply the requisite torque to open, close, and/or otherwise actuate the mixture control valve in certain engine operating conditions. Moreover, the governors of the '231 patent may not control the mixing valve using an internal feedback mechanism.

The disclosed valve actuation assembly is directed toward overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

In one exemplary embodiment of the present disclosure, a valve actuation assembly includes a housing and a vane connected to a shaft. The vane is at least partially disposed within the housing. The valve actuation assembly further includes a valve assembly connected to the housing and a feedback device connected to at least one of the vane and the shaft. The feedback device is configured to apply a feedback force to the valve assembly.

In another exemplary embodiment of the present disclosure, a valve actuation assembly includes a housing defining a chamber, and a vane disposed within the chamber and connected to a shaft of the valve actuation assembly. The valve actuation assembly also includes a valve assembly connected to the housing, and a feedback device in communication with the valve assembly and connected to at least one of the vane and the shaft. The feedback device is configured to assist in controlling the position of the vane within the chamber.

In still another exemplary embodiment of the present disclosure, a method of controlling a mixing valve with a valve actuation assembly having a valve assembly connected thereto includes sensing at least one of an operating characteristic of a power source and a flow characteristic of an exhaust flow of the power source. The method also includes determining a desired mixing valve position based on the sensing and changing the position of a spool of the valve assembly to a biased position. The method further includes changing the position of a vane of the valve actuation assembly to an equilibrium position using a pressurized working fluid. The equilibrium position corresponds to the desired mixing valve position. The method still further includes providing internal position feedback to the valve assembly representative of an actual vane position.

DETAILED DESCRIPTION

As shown inFIG. 1, an actuation assembly10, according to an exemplary embodiment of the present disclosure, may include a valve assembly25connected to a housing14. The actuation assembly10may also include a top cover12and a bottom cover16connected to the housing14, and an adapter plate18connected to the bottom cover16. The actuation assembly10may further include a shaft24at least partially disposed within the housing14. At least a portion of the shaft24may extend outside of the housing14. As shown inFIG. 1, the shaft24may extend beyond the adapter plate18. In an exemplary embodiment, the adapter plate18may be configured to connect to a mixing valve62, and the shaft24may be configured to controllably actuate components of the mixing valve62when the actuation assembly10is connected thereto.

The housing14may define a supply port28and a drain port30. The supply port28and the drain port30may be configured to accept a working fluid, such as, for example, pressurized oil from an oil sump (not shown). The ports28,30may also be configured to direct oil from the housing14to the oil sump. As will be described in greater detail below, the housing14may also define a plurality of additional passages and/or channels configured to direct a flow of fluid through the housing14and/or between the supply port,28, the drain port30, and a vane channel50(FIG. 3) of the housing14. The housing14may also include one or more plugs49configured to substantially fluidly seal such passages and/or channels.

The housing14may be made of any material known in the art, such as, for example, steel, aluminum, and/or alloys thereof. Such materials may be capable of withstanding operating temperatures in excess of 150 degrees Celsius without experiencing a substantial degradation in structural integrity. In an exemplary embodiment, the top cover12, bottom cover16, and housing14may be made of the same material, and each of these components may have substantially the same thermal expansion rate. It is understood that the actuation assembly10may have any shape, size, and or other configuration so as to maximize the torque supplied by the shaft24. It is also understood that the overall size of the actuation assembly10may be desirably minimized so as to reduce the amount of space required to package the actuation assembly10within, for example, an engine compartment of a work machine.

With continued reference toFIG. 1, the valve assembly25may include a control valve26and a connector60. Although shown inFIG. 1as connecting to a side portion of the housing14, it is understood that the control valve26may be mounted anywhere along the housing14to controllably regulate the passage of one or more flows of working fluid through housing14. The connector60may be any electrical connector known in the art. In an exemplary embodiment, the connector60may be configured to transmit and/or receive electronic signals containing, for example, control valve actuation and/or position information. The control valve26may include any controllable actuation device known in the art. In an exemplary embodiment, the controllable actuation device may include a solenoid (not shown) having a cylinder configured to move along a solenoid axis when the solenoid is energized. In such an embodiment, the connector60may be configured to transmit an electric current to the solenoid to energize the solenoid and facilitate the controlled movement of the cylinder. It is understood that, although described herein as an electric control valve including a solenoid, the control valve26may be any other type of control valve known in the art. The control valve26may be a two-way, three-way, or four-way valve.

As shown inFIG. 2, a bias spring36may be disposed around shaft24. In addition, a vane38may be rigidly connected to the shaft24, and the bias spring36may be in communication with vane38. Although a single bias spring36is illustrated inFIG. 2, it is understood that the actuation assembly may include additional bias springs36in communication with the vane38and/or the shaft24. The bias spring36may be configured to apply a spring force to the vane38and/or the shaft24. This spring force may bias the vane38and/or the shaft24to assume the position shown inFIG. 3. In an exemplary embodiment, the bias spring36may be connected to the vane38and may pass through a portion of the vane38. Alternatively, the bias spring36may extend along and/or act on a shelf37of the vane38.

It is understood that the actuation assembly10may also include one or more bushings20configured to assist in securing the shaft24and reducing the wear on components of the actuation assembly10over time due to rotation and/or other movement. The actuation assembly10may also include a number of bolts, dowels, and/or other structures known in the art to assist in, for example, connecting the top cover12, the housing14, the bottom cover16, and/or the adapter plate18.

Although shown inFIG. 2as including a threaded section, it is understood that the control valve26may include any conventional means or structure to facilitate the connection between the control valve26and the housing14. The control valve26may be inserted through a valve orifice32of the housing14and, in an exemplary embodiment, the valve orifice32may include threads and/or other connection structures corresponding to those located on the control valve26. The control valve26may also include a casing27. The casing27may define a number of flow orifices29configured to permit working fluid to flow into and/or out of the casing27. It is understood that the control valve26may also include any number of sealing structures31, such as, for example, O-rings or other structures known in the art. In an exemplary embodiment of the present disclosure, the sealing structures31may be disposed about a surface of the casing27. The sealing structures31may assist in fluidly sealing portions of the control valve26when, for example, the casing27is disposed within and fluidly connected to the housing14. Although shown inFIG. 2as being substantially cylindrical, it is understood that the casing27and/or other portions of the control valve26disposed within the housing14may be any shape known in the art. In an exemplary embodiment, the casing27may be substantially hollow.

As shown inFIG. 3, the control valve26may further include a spool48disposed within the casing27. The spool48may be connected to the cylinder of the solenoid described above and may be slidably movable within the hollow casing27. It is understood that movement of the spool48within the casing27may permit and/or substantially restrict a flow of working fluid to pass through one or more of the flow orifices29(FIG. 2) of the control valve26.

As illustrated inFIG. 3, the housing14may define a first passage46and a second passage47. The passages46,47may be formed in the housing14by any machining process known in the art, such as, for example, drilling or milling. In an exemplary embodiment, the supply port28may be fluidly connected to the first passage46. In another exemplary embodiment, the casing27of the control valve26may facilitate a fluid connection between the supply port28and the first passage46when the control valve26is disposed within and fluidly connected to the housing14. In such an embodiment, actuation of the spool48may assist in fluidly connecting the supply port28to the first passage46. Actuation of the spool48may also assist in fluidly connecting the drain port30to the second passage47of the housing14.

As mentioned above, the housing14may also define a vane channel50. The vane38may be disposed within the vane channel50and may be configured to rotate within the vane channel50as a force is applied thereto. Such rotation is illustrated by clockwise rotation arrow56and counterclockwise rotation arrow57. As will be described in greater detail below, such a force may be applied to the vane38by, for example, supplying a pressurized flow of working fluid to the vane channel50through the first passage46.

As illustrated inFIG. 3, the first passage46and the second passage47may be fluidly connected to the vane channel50. As will be described in greater detail below, a fluid may flow from the second passage47through a second passage orifice44.

It is understood that the fluid flows described above may also be reversed as the direction of vane rotation with the vane channel50changes. As discussed above, the housing14may define additional channels and/or passages (not shown) for passing fluid between the vane channel50and the first passage46or the second passage47as the vane38rotates. Thus, a fluid may pass into the vane channel50via a channel orifice45. Although not shown inFIG. 3, it is understood that the housing14may also define fluid passages connecting the second passage orifice44to the channel orifice45.

The vane38may be any shape, size, and/or configuration known in the art. The vane38may be made of any of the materials discussed above with respect to the housing14. The vane38may be rigidly connected to the shaft24in any conventional manner such that rotation of the vane38causes a corresponding rotation of the shaft24. For example, the vane38may be press-fit onto the shaft24. Alternatively, the shaft24may be keyed to facilitate a rigid connection with the vane38. The vane38may include one or more vane seals40configured to form a fluid seal between the vane38and the housing14as the vane38rotates within the vane channel50. For example, as the vane38rotates in a counterclockwise direction, the vane seal40may substantially restrict a fluid disposed within the vane channel50from flowing around a perimeter of the vane channel50from the left side of the vane38to the right side of the vane38. The vane38may also include one or more expansion devices41, such as, for example, a V-spring. The expansion device41may apply a force to the vane seal40to assist in forming a seal between the vane38and the housing14. The vane seal40may be made of any material known in the art capable of forming a seal between two moving parts while minimizing the friction formed therebetween. Such materials may include, for example, Teflon. As shown inFIG. 3, the housing14may also include a vane seal42and an expansion device43. The vane seal42and expansion device43may be configured to substantially restrict a fluid from passing from the vane channel50to other parts of the housing14while the vane38rotates. The vane seal42may be mechanically similar to the vane seal40described above. Similarly, the expansion device43may be mechanically similar to the expansion device41described above.

As discussed above, the bias spring36may be configured such that at least a portion of the bias spring36may impart a spring force onto the shelf37. The spring force may act upon the shelf37in the clockwise direction illustrated by clockwise rotation arrow56and may bias the vane38to substantially fluidly seal the first passage46when the vane38is in a resting position, as shown inFIG. 3. Thus, for the vane38to rotate in a counterclockwise direction, from the position shown inFIG. 3to another position within the vane channel50, the vane38may overcome the spring force applied by the bias spring36.

The actuation assembly10may also include a feedback spring34connected to the shaft24and/or the vane38. The feedback spring34may also be in communication with the spool48. Thus, the feedback spring34may maintain contact with the spool48whether the vane38rotates in a clockwise or counterclockwise direction. As the vane38rotates in the counterclockwise direction, the spring force imparted by feedback spring34to the spool48may increase. Conversely, when the vane38rotates in the clockwise direction, the spring force imparted by the feedback spring34to the spool48may decrease. While the actuation assembly10has been described above as including a bias spring36and a feedback spring34, it is understood that the actuation assembly10may also include any other conventional devices capable of providing a biasing force and/or a feedback force to the components of the actuation assembly10and/or the valve assembly25.

As shown inFIG. 4, a portion of the feedback spring34may pass through the vane38while maintaining contact with the spool48of the control valve26. It is understood that the actuation assembly10may further include one or more housing seals58configured to substantially fluidly seal components of, for example, the housing14. The housing seals58may also assist in forming a fluid seal between, for example, the housing14, and the top cover12and/or the bottom cover16. The actuation assembly10may also include a high pressure seal54and a low pressure seal52disposed around the shaft24. Similar to the seals described above, the high pressure seal54and low pressure seal52may form a fluid seal around the shaft24and may substantially restrict fluid from exiting the bottom cover16as the shaft24rotates. The seals58,54,52may be made of any sealing material known in the art, such as, for example, Teflon or rubber. In an exemplary embodiment, the housing seal58may be a gasket, and the high pressure seal54and low pressure seal52may be O-rings.

INDUSTRIAL APPLICABILITY

The actuation assembly10of the present disclosure may be used to actuate any type of flow control valve known in the art. Such flow control valves may include, for example, mixing valves configured to controllably combine multiple fluid flows into a single fluid flow at a desired ratio. Such mixing valves may be fluidly connected to an inlet of, for example, a spark ignition engine, a diesel engine, or any other power source known in the art. The power source may be used in any conventional application where a supply of power is required. For example, the power source may be used to supply power to stationary equipment, such as power generators, or other mobile equipment, such as vehicles. Such vehicles may include, for example, automobiles, work machines (including those for on-road, as well as off-road use), and other heavy equipment.

The actuation assembly10may be configured to impart a large amount of torque to the mixing valve62through a mechanical connection between the shaft24and components of the mixing valve62. The actuation assembly10may be significantly smaller and more compact than existing systems using, for example, motors, vacuum sources, pneumatic systems, or hydraulic cylinders to rotate the shaft24. In addition, components of the actuation assembly10may provide internal position feedback to the valve assembly25used to control the position of the vane38and the shaft24. This internal position feedback may be in the form of the spring force applied to the spool48by the feedback spring34. The use of internal position feedback to control the position of the shaft24may assist in more accurately controlling the ratio of, for example, recirculated exhaust gas to ambient air directed to a power source64by the mixing valve62. The operation of the actuation assembly10will now be described in detail with respect toFIG. 1unless otherwise noted. It is understood that the dashed lines originating from and terminating at the electronic control module (“ECM”)78inFIG. 1represent electrical or other control lines. The solid lines connecting each of the components ofFIG. 1represent fluid flow lines.

As illustrated by flow arrow68, the power source64may produce a flow of exhaust gas. After exiting the power source64, the exhaust gas may pass through an aftertreatment system74of the power source64. Components (not shown) of the aftertreatment system74may remove a portion of the pollutants contained within the exhaust gas before the exhaust gas is released into the environment. A portion of the filtered exhaust gas may also be recirculated to an intake66of the power source64. As illustrated by flow arrow70ofFIG. 1, recirculated exhaust gas may pass through, for example, an EGR line (not shown) of the aftertreatment system74. The EGR line may direct the portion of the filtered exhaust gas to the mixing valve62. As illustrated by flow arrow72, the mixing valve62may combine the exhaust gas with a flow of ambient air to produce a single intake flow. The single intake flow may be directed to the intake66of the power source64, as illustrated by the flow arrow88. The actuation assembly10may be mechanically connected to the mixing valve62and may be configured to control the ratio of ambient air to recirculated exhaust gas directed to the power source64by the mixing valve62.

During operation of the power source64, the ECM78may receive one or more signals containing power source operating characteristic information and/or recirculated exhaust gas flow characteristic information. As shown inFIG. 1, the power source64may include one or more sensors86configured to detect power source operating characteristics. The sensed operating characteristics may include, for example, throttle position, oil pressure, power source temperature, and/or power speed. It is understood that the aftertreatment system74may also include one or more sensors76configured to sense one or more characteristics of the recirculated exhaust gas flow. Such flow characteristics may include, for example, mass air flow, flow temperature, and/or particulate content of the exhaust gas. In an exemplary embodiment of the present disclosure, the sensor76may be disposed within the EGR line of the aftertreatment system74.

As illustrated by signal arrow82and signal arrow84, the ECM78may receive signals sent from the sensors76,86, respectively, and may enter the information contained in the signals into one or more preset algorithms. Using these algorithms, the ECM78may calculate, for example, the current position of the mixing valve62. The ECM78may also calculate a desired mixing valve position based on the sensed characteristics. In addition, the ECM78may determine whether or not to change the current position of the mixing valve62to the desired mixing valve position, thereby changing the ratio of recirculated exhaust gas to ambient air flow entering the intake66of the power source64, based on these calculations. The ECM78may use, for example, a number of preset mass air flow maps stored in its memory to assist in making this determination. If the ECM78determines that a change in the above ratio is required, the ECM78may generate an input signal and may send the input signal to the control valve26. The input signal, represented by command arrow80ofFIG. 1, may correspond to the calculated desired mixing valve position discussed above. The input signal sent by the ECM78cause an electrical current to be directed to the solenoid within the control valve26, thereby energizing the solenoid. Energizing the solenoid may cause the cylinder within the control valve26to change its position.

Actuation of the cylinder may cause the cylinder to apply a force to the spool48and may cause the spool48to move from a neutral position (illustrated inFIG. 3) to a biased position. In the biased position, the force applied to the spool48by the cylinder is greater than the spring force applied by the feedback spring34. In an exemplary embodiment, when the solenoid is energized, the cylinder and the spool48may move in the direction of actuation arrow81(FIG. 3). In such an embodiment, the force applied to the spool48by the cylinder and the angular position of the shaft24may be substantially directly proportional to amount of current directed to the control valve26. It is understood the force applied to the spool48by the cylinder may be balanced by the spring force applied to the spool48by the feedback spring34. It is also understood that this spring force may be related to the angular position of the shaft24and/or the vane38.

When the spool48is in the neutral position, a pressurized working fluid, such as, for example, oil may be prohibited from passing through at least the first and second passages46,47. When the spool48is in the biased position, however, oil may be permitted to pass into and out of the vane channel50. Oil may also be permitted to pass through the hollow casing27and through at least the first and second passages46,47of the housing14. The oil entering the vane channel50may apply an oil force to the vane38to effect a change in the angular position of the vane38. The vane38may rotate in, for example, the direction of counterclockwise rotation arrow57until the vane38and the shaft24reach an equilibrium position in which the force applied to the spool48by the feedback spring34equals the force applied to the spool48by the cylinder. In this equilibrium position, the spool48may be forced back to the neutral position illustrated inFIG. 3and oil may again be prohibited from passing through at least the first and second passages46,47. The equilibrium position may correspond to the desired mixing valve position discussed above. The desired mixing valve position may result in a desired ratio of ambient air and recirculated exhaust gas flow entering the intake66of the power source64.

It is understood that as the vane38moves in a counterclockwise direction, the spring force applied to the spool48by the feedback spring34may increase. As this feedback force increases, it may overcome the force applied to the spool48by the cylinder of the energized solenoid. As a result, the spool48may move in the direction of arrow83. Movement of the spool48in this direction may result in pressurized oil flowing through the casing27and through the first and second passages46,47such that the continued movement of the vane38may be counteracted. Oil may continue to flow through the actuation assembly10in this manner until the force applied to the spool48by the feedback spring34equals the force applied to the spool48by the cylinder and the spool48returns to the neutral position. The vane38and the shaft24may remain at the equilibrium position once the spool48returns to its neutral position and at least the first and second passages46,47are substantially fluidly sealed.

It is also understood that to move the vane38in the direction of the clockwise rotation arrow56to a new equilibrium position, pressurized oil may be supplied to the vane channel50through, for example, the channel orifice45. Rotation of the vane38in the clockwise direction may be induced by reducing the current supplied to the solenoid of the control valve26. Such a reduction in current may cause the spool48to move in the direction of arrow83. Such movement of the spool48may cause oil to exit the vane channel50through, for example, the first passage46. In this scenario, the spring force exerted by the feedback spring34may decrease until a new vane equilibrium position is reached.

It is further understood that the actuation assembly10described above may be operable in an open-loop and/or a closed-loop control environment. In an exemplary closed-loop control strategy, the ECM may continually receive signals from the sensors86,76during operation of the work machine. In such an exemplary embodiment, the ECM may repeatedly determine the desired mixing valve position based on the sensed operating and flow characteristics. In addition, the ECM may repeatedly generate command signals and send the signals to the control valve26. Thus, the position of the vane38may be changed multiple times based on repeated calculations and/or determinations made by the ECM as a work machine application is performed. Alternatively, in an exemplary open-loop control strategy, the van position may be changed based on a single calculation and/or determination by the ECM. In such an exemplary embodiment, the open-loop control strategy may be initiated manually.

It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the disclosed actuation assembly10without departing from the scope of the invention. For example, in an embodiment, the actuation assembly10may include a filtration device, such as a screen or mesh, connected to the supply port28and/or the drain port30and configured to substantially prohibit foreign objects suspended in the pressurized oil from entering the actuation assembly10. Other embodiments of the invention will be apparent to those having ordinary skill in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.