Patent Publication Number: US-11047506-B2

Title: Valve assembly and method of cooling

Description:
RELATED APPLICATION 
     This application claims priority as a continuation of U.S. patent application Ser. No. 15/057,636, filed Mar. 1, 2016 and entitled “Valve Assembly and Method of Cooling,” which application claims priority to U.S. Provisional Application No. 62/127,164, filed Mar. 2, 2015 and also claims priority as a continuation in part of U.S. patent application Ser. No. 14/471,410 filed Aug. 28, 2014, entitled “Remote Electro-Hydraulic Actuator,” which application further claims priority to U.S. Provisional Application No. 61/871,564 filed Aug. 29, 2013. Each of these applications is incorporated by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present invention relates to a valve assembly. In particular, embodiments of the invention relate to a valve assembly having a coolant ring to provide thermal isolation to an actuator assembly. Further embodiments of the invention relate to a valve assembly with an improved mechanism for attaching a valve plate. 
     BACKGROUND 
     Industrial, residential and mobile, including power generation, transportation, automotive and aerospace, controls systems often require actuation of mechanical components. Mechanical components of such systems may include valves that must be actuated. Such actuation is generally accomplished via pneumatic, hydraulic or electric components and/or systems. There are generally three different remote controlled types of valve actuation. 
     Valve actuation may be accomplished by electric components, including permanent magnet direct current (PMDC) motors, brushless direct current (BLDC) motors, direct current stepper motors, linear or rotary solenoids. Electric actuation is susceptible to environmental temperatures and suffers from reliability issues, especially in mobile applications due to the variations in operating environment and the harsh engine compartment/under hood environment. 
     Valve actuation may also be accomplished by pneumatic or electro-pneumatic means using pneumatically controlled linear or rotary actuators. Such actuators may include on/off or proportional actuation. Pneumatic and electro-pneumatic systems suffer from low position accuracy due the compressible nature of the fluid, typically atmospheric air, used for actuation and the moisture generated in the air compressor system. 
     In addition, valves in mechanical systems may be actuated by electro-hydraulic means, using hydraulically controlled linear or rotary actuators. Such actuators may employ on/off or proportional control. Conventional electro-hydraulic actuators use oil from the engine lubricating system or other high-pressure hydraulic power assist systems. The pressures of the engine lubricating systems are in the neighborhood of 100 psi and vary with engine speed. 
     BRIEF DESCRIPTION OF THE PRIOR ART 
     Electro-hydraulic actuators are known in the prior art. For example, U.S. Pat. No. 7,419,134 to Gruel is titled “Valve Actuation Assembly.” European Patent Publication No. EP 0 248 986 to Vick et al. is titled “Rotary Vane Hydraulic Actuator.” U.S. Pat. No. 5,007,330 to Scobie et al. is titled “Rotary Actuator and Seal Assembly for Use Therein. U.S. Pat. No. 6,422,216 to Lyko et al. is titled “Exhaust Gas Recirculation Valve.” 
     Electro-mechanical actuators are also known in the prior art. For example, U.S. Pat. Nos. 7,591,245 and 7,658,177 to Baasch at al. are titled “Air Valve and Method of Use.” Int&#39;l Pub. Application No. WO 2010/123889 to Baasch is titled “Exhaust Gas Recirculation Valve and Method of Cooling.” 
     Application of the Invention 
     Embodiments of the invention may be used, for example in automotive, aeronautical, rail or other transportation applications of internal combustion engines. In order to minimize pollutants produced by internal combustion engines, a portion of the engine exhaust may be recirculated to an intake of the engine. An exhaust gas recirculation (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. 
     This application incorporates by reference U.S. Provisional Application No. 61/871,564 filed Aug. 29, 2013, U.S. patent application Ser. No. 14/471,410 filed Aug. 28, 2014, and International App. No. PCT/US2014/053108 filed Aug. 28, 2014, all entitled “Remote Electro-Hydraulic Actuator.” 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a single vane rotary actuator as is known in the prior art. 
         FIG. 2  shows a perspective view of a piston rotary actuator as is known in the prior art. 
         FIG. 3  shows a cross-sectional view of the piston rotary actuator of  FIG. 2 . 
         FIG. 4  shows a perspective view of a valve and actuator in accordance with embodiments of the present invention. 
         FIG. 5  shows a top view of the valve and actuator of the embodiment of  FIG. 4 . 
         FIG. 6  shows an exploded view of a valve assembly according to an embodiment of the invention. 
         FIG. 7  shows and exploded view of an actuator assembly according to an embodiment of the invention. 
         FIG. 8  is a perspective view of the actuator assembly of  FIG. 7 . 
         FIG. 9  is a perspective view of an actuator main housing according to an embodiment of the invention. 
         FIG. 10  shows a top view of a vane rotational assembly according to an embodiment of the invention. 
         FIG. 11  shows a perspective view of the vane rotational assembly of  FIG. 10 . 
         FIG. 12  is a partial cross-sectional view of an actuator assembly in accordance with an embodiment of the invention. 
         FIG. 13  is a cross-sectional view perpendicular to the rotational axis of an upper actuator assembly cover in accordance with an embodiment of the invention. 
         FIG. 14  is a cross-sectional view parallel to the rotational axis of an upper actuator assembly cover in accordance with an embodiment of the invention. 
         FIG. 15  is a second cross sectional view of the upper actuator assembly cover of  FIG. 14 . 
         FIG. 16  is a perspective view of a lower actuator assembly cover in accordance with an embodiment of the invention. 
         FIG. 17  is a perspective view of an upper actuator assembly cover in accordance with an embodiment of the invention. 
         FIG. 18  is a perspective view of a spool valve as used in embodiments of the invention. 
         FIG. 19  is a perspective view of the upper actuator assembly cover of  FIG. 17 . 
         FIG. 20  is a perspective view of a valve and actuator in accordance with embodiments of the present invention. 
         FIG. 21  is a cross-sectional view of the valve and actuator of  FIG. 20 . 
         FIG. 22  is a perspective view of a valve assembly in accordance with embodiments of the present invention. 
         FIG. 23  is an exploded view of the valve assembly of  FIG. 22 . 
         FIG. 24  is a cross-sectional view of the valve assembly of  FIG. 22 . 
         FIG. 25  is a cross-sectional view of an embodiment of a shaft and pin for use with the valve assembly of  FIG. 22 . 
         FIG. 26  is a cross-sectional, perspective view of an embodiment of a valve body and coolant bushing for use with the valve assembly of  FIG. 22 . 
         FIG. 27  is a perspective view of the coolant bushing of  FIG. 26 . 
         FIG. 28  is a cross-sectional, perspective view of the coolant bushing of  FIG. 26 . 
         FIG. 29  is a perspective view of an alternative embodiment of the coolant bushing of  FIG. 27 . 
         FIG. 30  is a cross-sectional, perspective view of an alternative embodiment of the coolant bushing of  FIG. 28 . 
         FIG. 31  is a perspective view of a further alternative embodiment of the coolant bushing of  FIG. 27 . 
         FIG. 32  is a cross-sectional, perspective view of a further alternative embodiment of the coolant bushing of  FIG. 28 . 
         FIG. 33  is a perspective view of an alternative embodiment of valve and actuator of  FIG. 20 . 
         FIG. 34  is a cross-sectional view of the valve and actuator of  FIG. 33 . 
         FIG. 35  is a perspective view of a further alternative embodiment of valve and actuator of  FIG. 20 . 
         FIG. 36  is a cross-sectional view of the valve and actuator of  FIG. 35 . 
     
    
    
     DETAILED DESCRIPTION 
     There are several design variants of rotary electro-hydraulic actuators as known in the prior art and shown in  FIGS. 1-3 .  FIG. 1 , for example illustrates a single vane rotary actuator. Such an actuator  100  includes a base or lower cover  102 . A housing  104  with a cylindrical interior extends from the lower cover. An upper cover (not shown) covers the other end of the housing  104 . The actuator  100  further includes a rotational assembly  106 , which includes a hub  108  and a vane  110 . In addition, the actuator includes a partition wall  120 . The vane in conjunction with the partition wall divides the interior of the housing into two chambers  112 ,  114 . The actuator also includes an input port  116  and a return port  118 . Accordingly, when hydraulic fluid is pumped into the actuator through the input port  116  and fluid is allowed to exit through the return port, the actuator will rotate in a first direction. When fluid is pumped into the actuator through the return port  118  and fluid is allowed to exit through the input port, the actuator will rotate in the opposite direction. A shaft  122  extends from the hub  108  to transfer torque to the device to be actuated. The flow direction and rate are controlled via a remote or onboard control valve. These are usually spool valves or poppet valves. 
       FIGS. 2-3  illustrates an alternative electro-hydraulic actuator as known in the prior art using a cylinders  202 ,  204  and pistons  206 ,  208  connected by a rod  210 . The rod  210  includes teeth  214  that engage with teeth  216  on a rotating member  218 . In such a system, the hydraulic pressure is applied to one or the other piston through ports  220  or  222 . This causes the rod  210  to translate, which imparts rotational motion to the rotary member  218 . This rotary motion can be output from the actuator via a hub  224 . 
     In almost all rotary applications the valve is of the single vane design, such as shown in  FIG. 1 . However, in such actuators, the torque that the actuator is capable of producing is proportional to the effective surface area of the vane. In order to increase the available torque, the vane surface area, and thus the size of the actuator must be increased. Accordingly, it may be advantageous to utilize an actuator having more than one vane. For example, using two vanes effectively doubles the available torque without increasing the overall size of the actuator. Provided, however, that increasing the number of vanes allows for increased torque by increasing the vane areas but with a reduction of the range of rotational movement of the actuator. A single vane actuator has a potential rotational capability of about 300 degrees, depending of the chamber partition wall and vane thickness, while a two-vane actuator rotation have about 150 degrees and a three vane actuators has about 80 degrees rotation, etc. 
     One of the major challenges of a multi-vane rotary actuator is to route the pressurized hydraulic fluid to the input and output ports of the actuator. For example, when the valve is commanded to move clockwise, one (or more) chamber(s) is pressurized while another one (or more) chamber(s) is discharged to a reservoir. The routing of the fluids may be controlled via a multiport spool valve but the required input and output passages required to be routed from the spool valve to the chambers can be complex and requiring a multi-way spool valve options that are expensive and significantly increase the overall size of the actuator. Embodiments of the present invention address this and other deficiencies of the prior devices. 
       FIGS. 4-5  illustrate a valve assembly  301  and actuator  308  in accordance with embodiments of the present invention. A butterfly valve plate  302  is positioned within a valve housing  304 . The valve housing may be installed in the exhaust system of an internal combustion engine. The butterfly valve plate  302  may be opened and closed to control the flow of fluid through the housing  304 . Support posts  306  extend from an outside surface of the housing. The support posts may be used to mount an actuator  308 . The posts may also provide thermal insulation for the actuator assembly, protecting it from the heat of the exhaust gases passing through the housing  304 . 
     In addition, insulating washers  310  may be mounted on posts  306  to minimize the conductive heat transfer. Other means of minimizing convective and radiant heat transfer into the actuator is making the use of heat shields. These heat shields can be in for of single-walled or multi-walled designs containing insulating materials or just relay on an air gap. Alternatively, other mounting means may be used to secure the actuator  308  to the valve housing  304 . Additionally, the lower cover  314 , housing  318  and upper cover  312  may include holes  322  (see  FIG. 7 ) that provide a means for securing the actuator  308  to the posts  306  and the valve assembly  304 . For example, bolts  323  (shown in  FIG. 4 ) may be inserted through holes  322  into posts  306 . In the illustrated embodiment, the actuator assembly is attached to the flow modulating device, valve  301 , via four M10 bolts  323 . Depending on the geometric shape and size of the actuator the number of bolts can be reduced in number or changed in size. 
       FIG. 6  illustrates an embodiment of the valve assembly  301 . The valve in this embodiment is a butterfly valve. The main function of the butterfly valve described in this embodiment is to modulate fluids in internal combustion engines. Although references are made that the butterfly is being used on internal combustion engines it can be used to control fluid flow for many applications, ranging from engines, industrial and residential fluid control systems. These fluids can be cold or extremely hot. In certain applications gaseous exhaust temperatures reach temperatures in excess of 800° C. and careful selection of the alloys is required. Modulating sealing surfaces, shaft journals and bearings and shaft seals are the major wear components of the valve and high nickel and cobalt alloys are required. In the case of this embodiment, a butterfly valve is being described because of its pressure balancing characteristics but flap valves can also be considered for this actuator application. 
     The illustrative valve assembly  301  includes a main valve housing  304 . A shaft  332  extends through a sidewall into the interior of the housing  304 . The valve assembly further includes a butterfly plate  406  positioned inside the housing  304 . The butterfly plate  406  includes first and second vanes  330  extending in opposite directions. The butterfly plate is connected to a shaft  332  that extends through the sidewalls on opposite sides of the housing. The shaft  332  may extend beyond the house wall on the side adjacent the actuator  308  in order to engage with a hub of the actuator. The butterfly valve vanes  330  may be connected with the shaft  332  by fasteners  334 , such as retention screws. The valve assembly may also include bushings or bearings  408  and a shaft end cap  412 . The end cap may be secured to the housing  304  by screws  413  or other fasteners in order to secure the shaft  332  in position. The valve can be configured to attain a normally open or a normally closed butterfly valve condition by adjusting the vane assembly or switching the hydraulic input/output ports. 
     The actuator of the present invention is not limited to use with the butterfly described herein. In addition to a butterfly or flap valve, embodiments of the actuator may be used with any flow-modulating device, including for example single or multiport gate valves, globe valves, disk valves, stem valves, or other appropriate valves. In addition, the actuator may be used in rotational and linear mechanical motion devices. The actuator may be used in any device that can accept rotational motion as an input, including devices where rotational motion is transformed into linear or other motion by screws, linkages, gear trains, rack-and-pinion assemblies, etc. 
     Embodiments of the actuator  308  are illustrated in  FIGS. 7-8 . The main function of the actuator is to position the fluid modulating valve  301  according to the required engine control parameters. The actuator represented in this embodiment is a dual vane design and has a total rotational travel of 85 degrees. Other vane configurations or rotational travel would be apparent to one of skill in the art. 
     The actuator  308  may comprise a housing  318 . The housing is sealed by an upper cover  312  and a lower cover  314 . However, while this and other embodiments described herein illustrate an actuator assembly having a housing with separate upper and lower covers, it should be understood that two or more of these components may be formed as a single piece. For example, the housing and upper cover may be formed as single piece, or the housing and lower cover may be formed as a single piece. 
     Embodiments of the actuator may also include a vane  504  for rotation within the housing  318 . The vane  504  may rotate on a bearing  508  and main include vane tip seals  522 . The housing  318  and covers  312 ,  314  may also incorporate housing seals  510  to better seal between the components. In addition, a main shaft seal assembly  514  may be used to seal against the shaft  322  extending from the valve assembly  301 . The shaft  322  may also engage with a standalone shaft sensor or contain part of the shaft positioning sensor assembly when used in conjunction with a shaft position sensor  518  and/or an electronic control circuit board  519  positioned beneath a cover  517 . 
     Single or multiple actuator control valves may be used in the application. The valve may be a two-way/two-position cartridge spool valve with a proportional design or any other appropriate valve. The valve may be incorporated into the upper cover  312  or into the lower cover  314  and fluid may be routed to chambers of the actuator as required. Alternatively, the valve may be incorporated into the side of the actuator. The control valve  516  may be coupled to fittings  327 ,  328  for connecting with a hydraulic pump of the hydraulic system or a pneumatic pump if a pneumatic system is used. 
     As shown in  FIGS. 7-8 , the upper cover  312 , housing  318  and lower cover  314  may include through holes  320 . Bolts, screws or other fasteners  321  may be inserted into these holes  320  in order to secure the covers  312 ,  314  to the housing  318 . In the illustrated embodiment, these fasteners include eleven M6 bolts. Depending on the geometric shape and size of the actuator the number of bolts can be reduced in number or changed in size. The holes  320  may be internally threaded or may provide other features that contribute to securing the components. The actuator  308  may have a generally central axis  324  about which the rotational assembly of the actuator rotates. The upper cover  312  may have reinforcing struts  326 . 
     As shown, by example, in  FIG. 7 , a bottom cover  314  of an actuator  308  may include an opening  336 . A hub  338  of the rotational assembly of the actuator may be exposed through the hole. As shown in  FIG. 9 , the hub  338  may include a female socket  340  recessed into the hub. The socket  340  may include splines  342  that engage with splines  333  formed on shaft  332 . The splines can be arranged symmetrically around the whole circumference or can be asymmetric or lost tooth format. The hub can be designed of any alloy, but given the tendency of high torque requirement and high temperature applications, the alloy selected will be of low heat conducting, high toughness and low wear characteristics. 
       FIG. 9  depicts an embodiment of the actuator main housing  318  and vane rotational assembly  648 . The depicted main housing consists of an extruded aluminum profile that attains near net shape conditions. Although other manufacturing processes such as die casting, forging, etc. can be used for this part, extruded aluminum profile provide near net shape parts that do not require major post manufacturing processes, offer dimensional stability and high physical properties. Extruded aluminum alloys also can be easily coated or plated with wear reducing and low friction coatings and plating. 
     The internal profile is designed to contain the travel end stops  612  and sealing surfaces  614  of the rotating vane  504 . Corner radii  604  of the internal profile are shaped to allow for any secondary profile clean up using robust machining tools. Passages for assembly bolts  606 , attachment screws  607  and coolant routing  608  are extruded to minimize the post machining processes. 
     The extrusion design option also allows the sizing of the actuator. The torque capabilities of the actuator are directly proportional to the area exposed to the pressurized working fluid. The area is a function of the diameter and length of the vane  504 , and thus extrusion generates an easy option to cut the actuator length within the extrusion length. The length of the actuator  610  is partially restricted by the packaging constraints but in general range from 25 mm to 75 mm. The actuator vane depicted in this application is 35 mm length to achieve the specified torque characteristics of 40 Nm of torque. 
     The main housing depicted in  FIG. 9  can be configured to house the working fluid inlet and outlet ports  327 ,  328  and the electric hydraulic control valves. Although inlet and outlet ports depicted are of the external flare style and of different size to eliminate assembly mistake they can be of any size, type and gender to achieve the required connection point and mistake proofing. 
     The actuator main housing is for a dual vane actuator design but the extrusion profile could be designed into any shape to achieve from single to multi vane actuator design with the gain in torque output but with loss of rotational range. As shown in  FIG. 9 , the housing has a generally cylindrical inner cavity. Partition walls  644  extend from an inner surface  646  of the cavity. A rotational assembly  648  is positioned for rotation about a central axis of the actuator housing. The rotational assembly includes a hub  338  with a first vane  654  and a second vane  656  extending from the hub. 
     To minimize internal leakage, the tip of the vanes  654  and  656  can be sealed against the inner surface  646  of the housing  318  by tip seals  614  or by using tightly toleranced parts and thermal conductive matched. Chamber seals  662  seal the ends of partition walls  644  against hub  338 . In addition, housing seals are fitted into grooves  664  in order to seal upper and lower covers to the housing  318 . In addition, bearings (not shown) may be utilized to facilitate rotation of the rotational assembly  318 . The bearings may be deep groove bearings. 
       FIG. 10  depicts a vane rotational assembly configuration used in an embodiment of the invention. Main functions of the vane in this application are to house the bearings, serve as the working fluid manifold, transmit rotational motion to device to be driven shaft and seal the working chambers. This seals can be of various types: force activated wiper seals and labyrinth style seals. 
     The area of the actuator vane exposed to the pressurized working fluid determines the performance to of the actuator assembly. In multi-vane actuator applications one of the main challenges is the routing of the working fluid to and from the required chambers and its manufacturability. Embodiments of the vane actuator may be manufactured by various methods, including extrusion and investment casting. Vane communication passages or manifolds  702 ,  703  are depicted in  FIG. 10 . These passages can be achieved via investment casting, 4-axis electrical discharge machining (EDM) or cross drilling. Spark eroding the communication channels with a 4 axis EDM process is slow and expensive and challenged by the line of sight and passage size restricted by the vane interior diameter feature that connects to the output shaft of the shaft from the device to be driven. Investment casting allows the option to cast the passages in circumferential geometry and allows for non-circular cross-section allowing the flow to be maximized. Special cores and core support have been designed to achieve this configuration. 
     The size and the geometry of this passage control the performance of the valve. Smaller holes or inserted orifii may restrict the fill of the secondary chambers while inserted check valves can time the fill of the secondary chambers. The flow area of the communication passages can be 10 to 50 mm 2  but in general are sized to 30 mm 2  as depicted in this embodiment to adapt commercially available check valves. 
     In the case of investment casting and extrusion, which are of the near net shape manufacturing processes, features  704  are formed into the vane geometry to minimize the final machining process and help in the use of highly robust cutting tools to minimize the manufacturing process cycle. Undercut areas  706  in the vane to hub area may be used to eliminate the need to use very small diameter contouring tools as well as serve as the starting edge for the cross drilling, 4-axis EDM or press feature for the check valves or orifii. 
     Sealing of the working chambers may be achieved with vane tip seals inserted into channels  710  formed at the tip of vanes  712 ,  713  and hub radial seals  708 . These seals can be dynamic seals like labyrinth seals or force activated static seals. Force activation is mainly achieved via elastomers or metal springs while the wiping element is a low friction chemically inert compound such as Teflon. 
       FIG. 10  depicts an internally supported vane via the bearings toward the hub extensions in the covers, externally supported vane is also possible but such a design does not allow for minimized packaging. 
     As illustrated in  FIG. 10 , an actuator in accordance with embodiments of the present invention flows the working fluid through strategically sized flow channels  712 ,  713  within the structure of the vane assembly. The ports and passageways are sized to provide dampening and improve the stability of the valve and can also be provided with pressure check valves or reed valves to dampen the rotation of the valve and reduce any instability due to pulsations driven back via the output shaft. 
     For example, vane  713  may include a port  723  formed in a first face  733  of the vane. The port  723  is connected via an internal passageway or manifold  703  to a port adjacent the opposite face  752  of the second vane  712 . Likewise, a port  722  on the first face  732  of the vane  712  is connected via an internal passageway or manifold  702  to a port  743  on the opposite face  753  of vane  713 . 
     In this manner, a pressurized flow of hydraulic fluid is applied to face  733  of vane  713  inducing the assembly to rotate in a clockwise direction. The fluid then passed through the body of the actuator assembly, through passageway  703 . The hydraulic fluid then applies pressure, to the opposite face  752  of vane  712  increasing the clockwise torque on the assembly. In a like manner, return flow applies a force to the face  753  of vane  713  to rotate the assembly in a counterclockwise direction. The return flow of fluid passed through passageway  702 . The hydraulic fluid then applies pressure to the face  732  of vane  712  increasing the counterclockwise torque on the assembly. Flow from the primary chamber to the secondary chambers can be delayed or dampened by the use of orifices and/or check valves. The use of such devices can increase the accuracy of the actuator and dampening characteristics due to the torque fluctuations imparted on the output shaft. 
     As illustrated in  FIGS. 9-10 , embodiments of the invention may use a two-vane rotational assembly. The assembly includes a hub  762 . Vanes  712  and  713  extend from the hub. In this embodiment, the vanes are offset at an angle less than 180 degrees in order to accommodate flow channels and valves in the actuator housing. The angle between the vanes will affect the maximum rotation of the actuator and may be any appropriate angle up to 180 degrees. Alternatively, the vane rotational assembly may have more or fewer vanes. The rotational assembly may be formed from multiple components joined together by known means. Alternatively, some or all of the components may be formed from as a single piece. 
     The support of the rotating members of this valve can be external or internal to the shaft/vane assembly. The use of shaft support in the form of ball bearings, needle bearings, bushings exclusively or combination thereof can generate packaging and cost advantages. 
     As illustrated in  FIGS. 10-11 , embodiments of the vane assembly include a hub  762 . Vanes  712  and  713  extend from the hub. A socket  740  is recessed into hub  762  for engaging a shaft extending from the device to be actuated. The socket  740  may include splines  742  for engaging corresponding splines on the device shaft. A bearing surface  749  may be formed on a surface of the hub  748  in order to engage with a bearing  750  for rotational movement. 
       FIG. 12  is a cross-sectional view of an actuator assembly of an embodiment. The actuator assembly includes an upper actuator cover  802  and lower actuator cover  804 . A function of the covers is to seal the working chambers  806  of the main housing, guide the vane rotation via the cover extension shafts  808 ,  809  and route the coolant as depicted in  FIGS. 13-15 . As illustrated in  FIGS. 13-15 , the upper cover  802  may include closed channels  812  drilled, casted (lost foam invested casting, etc.), formed or cut into the cover. This cooling channels can be machined or cast into the upper cover alone, lower cover alone or into both. The requirement is dictated by the source of the heat: conductive, convective or radiant. Hydraulic fluid provided by a hydraulic pump may be passed through these channels. For example, bypass fluid not used to actuate the actuator may be passed from the pump through the channels before being returned to a reservoir. This fluid may be used to cool the bottom cover and thus provide thermal insulation for the actuator  308 . Although the cooling circuit described in this invention makes use of the existing working fluid, either in parallel or in series circuits, the cooling circuit can also be an independent cooling system where engine coolant or any other cooling fluid can be used. 
     The origin of the oil can either be from diverting the supply line or passage, and flow may be determined by the amount of oil flow to achieve the cooling action. Sizing of the flow channel, by the use of casting techniques, inserted orifices, etc., determines the flow according the pressure available. Flow can also “timed” via a check valves that cut the diverted cooling oil flow at low oil pressure conditions. Oil pressure is directly related to engine load and thus to the temperatures in the exhaust, i.e. at idle where oil pressure is low (e.g. 20 psi) cooling flow is not required because exhaust gas temperatures are fairly low and do not affect the performance and durability of the actuator. 
     The cover  802  may have an inlet port  814  formed in an inside surface  818  of the cover that receives hydraulic fluid flowing though the valve and housing of the actuator. The fluid then passes through channels  812  formed in the cover. The fluid then exits through a port  816 . Inlet port  814  and outlet port  816  may be located at the cross over ports in the actuator housing. The cooling channels may create a cooling curtain that is sized to achieve the maximum surface area. The upper cover  802  may have an opening  838  through which the hub or shaft of the rotational assembly may be exposed. 
     Cooling flow may be made through the upper cover. Alternatively, the cooling flow can also pass through the main body or lower cover. Or the flow may pass through multiple or all of these portions depending which part of the actuator may benefit from being be cooled or protected. These flow passages can be in the form of drilled, caste or formed passages or rerouted by external conduits such as hoses and tubes. 
     As shown in  FIG. 12 , the upper cover in addition to above mentioned functions may also contain electronic control circuitry, electric/electronic input/output circuitry  901  and/or a shaft position sensor  905 . The shaft position sensor may be a standalone sensor. An additional function of the lower cover is to house a main shaft seal  907 , house additional sealing components  909  that contain minute exhaust leaks during extreme engine transients and serve as a structural interface to the valve or other device to be driven, for example through support posts  911 . Although the figure depicts covers without any control valves, the castings can easily be designed to contain the fluid control valve. 
     As depicted in  FIG. 16 , lower cover, and  FIG. 17 , upper cover, embodiments of the invention include a configuration in which routing and control of the coolant circuitry is positioned within a single-piece aluminum component. This unique design allows for one casting that fits multiple applications and that provides both lower and upper covers. The lower and upper raw castings or forgings are designed to be common and then machined according to the application. Machining variation can generate many different variants of the actuator according to its application, including: a smart drive by wire actuator, a passive actuator. For example, the lower cover  804  shown in  FIG. 16  use the same casting as the upper cover  804  of  FIG. 17 . The cover  802  may then be processed or machined to create an opening  836  to accommodate a shaft seal and become the lower cover. The cover may be processed to have an opening  838  that may accommodate sensors or other control circuitry and thus become an upper cover. In this way, the actuator may be internally cooled, top cooled or bottom cooled. It may also use fluid or gaseous cooling, serial or parallel cooling or no cooling. Such a symmetric configuration also has advantages for manufacturing tooling cost, only one casting or forging tool is required. The coolant circuit can be present in the upper or lower cover or both depending of the application. Aluminum lost foam, investment casting, forging and brazed, billet machined and brazed processes may be the processes of choice for this design but is dependent on production volume. 
     As shown in  FIGS. 18-19 , in embodiments of the present invention, directional and modulating control of the working fluid from one chamber to another of the actuator may be controlled via an electronic proportional solenoid  916 . Although hydraulic and pneumatic fluids are discussed in this application, any compressible or non-compressible gases and liquids can be used as the working fluid. The proportional solenoid can be of the push, pull or dual actuated style. The modulation can be achieved via a single multiport spool valve, multiple dual port spool valve or pairs of proportional poppet valves. Embodiments of the invention may include a control system that uses the valve, whether proportional, poppet or other, to maintain the position of the actuator. For example, the control system may include one differential or two absolute pressure sensors to sense the differential pressure across the two chambers. The control system periodically compares the pressure. If the control system detects a pressure differential, the system compensates by appropriately increasing or decreasing the fluid in the chambers. This balancing of fluid pressure between the chambers is accomplished using one or more of the valves as described. In this manner, the actuator can maintain the position of the actuator and thus the valve or other device being driven by the actuator. 
     Sizing of the ports and number of valves determines the response time of the actuator and the pressures losses that directly results in the loss of torque. The valve size may vary as appropriate for the application as would be understood by one of ordinary skill in the art. The actuator can be configured with the proportional solenoid valve in the upper cover, main actuator housing or lower cover. The solenoid depicted in  FIG. 18  is designed to be installed in the actuator main housing due to packaging constraints and to reduce the overall size of the actuator mechanism. 
     The proportional valve(s) can contain mechanical position feedback or electronic position feedback. In the case of mechanical feedback the spool of the valve is biased via a spring cam mechanism to attain and maintain the commended position. If electronic position feedback is used, Hall effect or similar sensors are being used to obtain spool position feedback. In an alternative embodiment, pressure feedback from the actuator working chambers may be used in commanded positioning and to aid in the critical dampening of the actuator/valve. These types of feedback maybe used to attain and maintain the spool position, which controls the actuator shaft position. 
     In embodiments of the invention, the position of the actuator is driven by the actuation of a proportional cartridge valve through an analog, pulse width modulated (PWM) or digital signals generated by an Engine Control Unit (ECU). The system can further be augmented with electronic/hydraulic logic to increase the self-sufficiency of the valve such as position, response time, etc. 
     In accordance with embodiment of the invention, it may be desirable to provide information regarding the rotational position of the rotating assembly such as the rotational position of the output shaft  332  shown in  FIG. 6  or the female socket  340  shown in  FIG. 9 . Such position feedback can be open loop or closed loop type. Open loop feedback depends only on the command control of the cartridge valve. Closed loop depends on one or more sensors that are either internal or external to the actuator. These sensors may be contact or contactless sensors, including linear variable differential transformer (LVDT), rotary variable differential transformer (RVDT), Hall effect, resolvers, analog wipers, etc. 
     Embodiments of the actuator may be configured with or without a shaft position sensor. In the case of open loop control the shaft position sensor is not required and the engine uses other sensors as well as mechanical hydraulic control valve force feedback to control the actuator and thus modulate the valve. In the case of closed loop control the shaft position sensor may be used for initial start-up calibration or continuous control. As shown in  FIGS. 17 and 19 , the upper cover  802  may include a cavity or recess  838  in which a sensor may be positioned. The cavity  838  may be covered or sealed by a cover  840 . The cover  840  may be secured to the upper cover  802  by screws  844  or other fasteners. Alternatively, the cover may itself have threads or engagement surfaces that engage with corresponding portions of the upper cover  802 . 
     Embodiments of the shaft position sensor can be of the standalone design were position feedback is being monitored by a remote centralized control system or installed on a circuit board for actuator onboard circuit design option for decentralized actuator/valve control system or hybrids thereof. In the case of standalone shaft position systems the shaft position sensor can be of the variable transformer, hall effect, magneto-resistive, inductive, capacitive, resistive, optic type or variants of thereof. In the case of integrated shaft positions sensor, the sensor is integrated into the circuit board of the decentralized control system and can be of the many variants discussed above. 
       FIG. 4  depicts an embodiment of the invention that includes a butterfly fluid modulating valve  302  with a multi-vane actuator, single-multiport proportional spool valve and shaft position feedback. This assembly may be monitored and controlled via remote controllers that can be standalone actuator controllers but can also be part of the engine control unit. This design has the disadvantage that electronic control, power and communication require large number of wires and complex electric connectors. Depending on the feedback and communication  12  wires or more are required. Such configuration suffers from communication time lags, susceptible to electromagnetic interference and electric wire/connector failure due to the harsh environmental conditions existent in the engine compartment. 
     In another embodiment, the valve is designed to contain its own controller. The communication can be analog or digital. Analog communication can be of the voltage or current type and in the digital case it can be PWM (Pulse Width Modulated), or via CAN (Central Area Network) and its variant. For industrial application these communication can be configured to use Ethernet, RS232, RS 485 and its other variants. This design option retains full actuator onboard control and onboard diagnostics. The circuit board components are selected for harsh environmental conditions and fully encapsulated to protect for cooling fluid exposure with the objective to protect the circuit from external and cool the circuit internal heat being generated. The fully encapsulated circuit board layout is configured to integrate all required major building blocks required for the control, protection and diagnostics of the actuator and the connection points via compliant pins to the input and output connections points for external or internal communications or control such as proportional solenoid valves. The encapsulated circuit board would transfer its heat via thermally conductive encapsulant or encapsulated heat sinks that are directly in contact with the cooling circuit. 
     The single layer or multilayer circuit board of such an embodiment of the actuator would contain all or part of the following main building blocks: microcontroller, a spool or poppet valve driver, circuit protection, shaft position sensor and I/O connection points in the form of hard mounted connector or flying lead. These building blocks can be generated using discrete components or highly integrated using proprietary AISIC/FPGA technology. The package size of the circuit board fits into machinable areas of 20 mm in diameter to 60 mm in diameter. As shown in  FIGS. 17 and 18  it may be installed to the upper cover  802  via screws  844 , clips or other retention mechanism commonly used in the industry. Alternatively, the circuitry could be installed in the main housing  308  (see  FIG. 4 ). 
     The actuator described herein may be referred to as a remote actuator. However, it will be understood that actuator can be remote but that, alternatively, its function and performance can also be built into the actuator or a valve associated with the actuator to reduce packaging and cost. 
     An embodiment of the present invention is shown in  FIGS. 20-28 . In the illustrated embodiments, a valve assembly  902  is attached to and functionally connected with an actuator assembly  904 . Bolts  906  pass through holes  938  in the valve assembly  902  and engaged threaded holes in the actuator assembly  904 . Other attachment mechanisms may be used. The actuator assembly may be an electro-hydraulic actuator as describe herein with respect to  FIGS. 1-19 . Alternatively, the actuator assembly may be an electro-mechanical actuator as illustrated in  FIGS. 20-28 . The actuator assembly may be any actuator that would benefit from cooling or thermal isolation as described herein. 
     The valve assembly  902  includes a valve body  908 . The valve body has a central, generally cylindrical through bore  910 . A butterfly valve plate  912  is positioned within the bore  910 . A shaft  914  passes through a central passage  916  formed within the butterfly plate  912 . The valve assembly also includes a perpendicular opening  920  formed through a sidewall of the central bore  910  adjacent to the actuator assembly  904  and a second perpendicular opening  918  formed through a sidewall of the central bore  910  opposite the actuator assembly  904 . The shaft  914  passes at least partially through these openings  918 ,  920  to allow the butterfly plate  912  to rotate within the valve housing bore  910 . Bushings  922  may be placed around the shaft  914  within the openings  918 ,  920  to allow smooth rotation of the shaft. 
     A position or other sensor  924  may be positioned over the opening  918  to engage the shaft  914 . Adjacent the actuator assembly  904 , the shaft  914  may extend through the hole  920  and into the actuator assembly to mechanically engage with the actuator. A flange  926  may extend from a sidewall of the shaft  912 , and various bushings  928  and seals  930  may be positioned around the shaft. 
     The valve assembly  902  may include a coolant ring  934  positioned between the valve housing  908  and the actuator assembly  904 . As particularly illustrated in  FIGS. 23-25 , embodiments of the coolant ring may be positioned within a cavity  936  formed in the actuator side of the valve housing  908 . A flange  940  of the valve housing  908  may extend around all or part of the coolant ring  934  such that the valve housing comes in contact with the actuator assembly  904  around the periphery of the coolant ring. The coolant ring may include a central bore  946  through which the shaft  914  can pass. 
     The geometry and routing of the coolant channels can be of any configuration depending on the cooling objective. In the case of heat transfer barrier helical configuration is adopted were the coolant is routed from the OD towards the ID as depicted in  FIGS. 31-32 . In the case of shaft cooling the cooling function is concentrated around the shaft as depicted in  FIGS. 27-28 . In the case heat barrier and shaft cooling is required a cooling ring with both cooling channels may be adopted. 
     As illustrated in  FIGS. 26-30 , the coolant ring  934  may include interior radial crossover coolant channels  942  that route the coolant from the inlet port  948  to the circumferential flow channel  964  adjacent to the shaft back to the outlet port  949 . A port sealing element  958  ( FIG. 21 ) may be used to connect the coolant channels  942  in the coolant ring with fluid passages  960  in the actuator assembly. The port sealing element  958  may be a tube or any other sealing feature such as gaskets, face or radial O-rings. The I/O ports depicted here are on the same side 180 degrees apart but these ports can be in any orientation and on alternate sides depending how the coolant is routed. The coolant fluid can be any appropriate fluid, including hydraulic fluid used to actuate an actuator assembly, bypass hydraulic fluid not used to actuate the actuator assembly, engine coolant fluid or any other fluid as would be apparent to one of ordinary skill in the art. 
     The coolant channels  942  may be offset from the centerline of the ring toward the valve housing  908 . The side of the coolant ring adjacent to the actuator assembly also may have one or more recesses  944  formed in the surface. The offset of the coolant channel  942  combined with the recess  944  may provide a number of advantages, including increasing the thermal isolation provided by the coolant ring to the actuator assembly as well as reducing the amount of material necessary to manufacture the coolant ring. 
     To enhance the heat transfer from the valve body to the coolant via the coolant ring, selection of alloys is optimized and contact resistance is minimized by the use of wave springs and/or thermally conductive paste or epoxies. For example, a wave spring  932  may be placed between the actuator body  904  and the cooling ring  934  to press the cooling ring against the valve assembly  902 . Additionally, a thermally conductive material  933 , including a paste or epoxy, may be positioned between the surface of the cooling ring  934  and the valve assembly  902  or between the cooling ring  934  and the actuator body  904 . 
     The coolant ring  934  may be provided as a modular ring or system of rings. In this manner, a system designer may choose a size and cooling capacity of the cooling ring based on the application, taking into account various factors, including: temperatures to which the valve assembly will be subjected, temperature limits of the actuator assembly, duty cycle of the system, ambient temperature, cooling capacity of the cooling fluid, and other factors as would be understood by one of ordinary skill in the art. 
     In embodiments as illustrated in  FIGS. 23-25 , the shaft  914  passes through a central passageway  916  of the butterfly plate  912 . The illustrated shaft has a generally cylindrical profile. However, a portion of the shaft within the plate passage way is milled or otherwise formed to create a flat section  950 . The butterfly plate includes a through hole  952 . This through hole is offset from the centerline of the butterfly plate so that it lies generally adjacent to but extending slightly into a side edge  954  of the central passageway  916 . A pin  956  is inserted into the hole  952 . The pin engages the flat section  950  of the shaft  914  and prevents the shaft from rotating within the central passageway  916  of the butterfly plate. A reinforcing structure  962  may be formed on the butterfly plate adjacent the through hole  952  to provide a stronger supporting structure for the pin  956 . 
     In this manner the butterfly plate and shaft may be effectively locked together for coordinated movement without the need to drill through the diverse materials of the plate and shaft or without the need to exactly align complimentary holes or other features formed in the plate and shaft.