Abstract:
Provided is a valve assembly having a thermal valve member and a priority valve member that are shiftable to first and second positions in response to a temperature and pressure of a fluid flowing through the valve assembly. Consequently, the valve can provide for flow through a heating orifice under low temperature, high pressure conditions so that pressure drops in fluid lines coupled to the valve assembly may be prevented or reduced, allowing fluid lines with small diameters to be used in an aircraft or other fluid flow system, thereby reducing the weight of the aircraft or fluid flow system.

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/332,894 filed May 10, 2010, which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a valve assembly, and more particularly to a hydraulic valve assembly responsive to temperature and/or pressure. 
     BACKGROUND OF THE INVENTION 
     Thermal actuators, such as wax motors, may be provided to convert temperature change into a force. Upon heating the thermal actuator, fluid disposed in the actuator is expanded, which causes a diaphragm to deform, thereby causing an axial movement of a piston adjacent the diaphragm. When the fluid is cooled, the fluid is contracted, which causes the diaphragm to return to its original state. Thermal actuators may be used in valves to open and close flow passages inside the valves. To minimize pressure drops caused by the thermal actuators, large diameter fluid tubes may be used. 
     SUMMARY OF THE INVENTION 
     The present invention provides a valve assembly having a thermal valve member and a priority valve member that are shiftable to first and second positions in response to a temperature and pressure of a fluid flowing through the valve assembly. Consequently, the valve can provide for flow through a heating orifice under low temperature, high pressure conditions so that pressure drops in fluid lines coupled to the valve assembly may be prevented or reduced, allowing fluid lines with small diameters to be used in an aircraft or other fluid flow system, thereby reducing the weight of the aircraft or fluid flow system. 
     In particular, the valve assembly includes a housing having an inlet for receiving fluid and first and second outlets for delivering the fluid from the valve assembly and thermal and priority valve members shiftable in the housing. The thermal valve member is shiftable by first and second springs between a first position permitting fluid flow from the inlet to the priority valve member and a second position blocking fluid flow, at least one of the springs being responsive to temperature changes of the fluid flowing through the housing. The priority valve member is shiftable against a biasing force by pressure at the inlet above a predetermined pressure, the priority valve member being shiftable between a first position blocking flow from the inlet to the second outlet and a second position permitting flow. 
     Preferably, the first and second springs shift the thermal valve member to the first position when the fluid is below a predetermined temperature and to the second position when the fluid is above the predetermined temperature. 
     The priority valve member is shifted to the first position when the pressure of the fluid is below the predetermined pressure and to the second position when the pressure is above the predetermined pressure. 
     The valve assembly includes a sleeve disposed in the housing that guides the thermal and priority valve members, wherein the sleeve includes a first opening for receiving fluid from the thermal valve member when the thermal valve member is in the first position, a second opening communicating with the first opening, a third opening communicating with the second opening, and an annulus communicating with the first and second openings. 
     The thermal valve member includes a first opening for receiving fluid and a second opening for delivering fluid to the first opening in the sleeve when the thermal valve member is in the first position. 
     The priority valve member includes an annulus communicating with the second and third openings in the sleeve when the priority valve member is in the second position. 
     According to another aspect of the invention, a method of delivering fluid through a valve assembly is provided, the valve assembly including a housing and thermal and priority valve members shiftable in the housing, wherein the thermal valve member is balanced by first and second springs, and wherein at least one of the springs is responsive to temperature changes of the fluid flowing through the housing. The method includes receiving fluid at an inlet of the housing, delivering the fluid to a first outlet of the housing, and delivering the fluid to a second outlet of the housing when the fluid has a temperature below a predetermined temperature and a pressure above a predetermined pressure. 
     The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-section view of an exemplary heater valve according to the invention, where a thermal spool and a priority spool are both in a first position; 
         FIG. 2  is a cross-section view of the heater valve according to the invention, where the thermal spool is in the first position and the priority spool is in a second position; 
         FIG. 3  is a cross-section view of the heater valve according to the invention, where the thermal spool is in a second position and the priority spool is in the second position; 
         FIG. 4  is a cross-sectional view of another heater valve according to the invention, where a thermal spool and a priority spool are both in a first position; 
         FIG. 5  is another cross-sectional view of the heater valve of  FIG. 4 ; and 
         FIG. 6  is a perspective view of an exemplary priority spring seat according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The principles of the present invention have particular application to valve assemblies used on airplanes, such as at the wing tips or at the tip of the tail, to heat fluid flowing through the valve assemblies to allow fluid circulation without creating a large pressure drop. It will of course be appreciated, and also understood, that the principles of the invention may be useful in other applications including hydraulic pumps, heat exchangers, etc. 
     Referring now in detail to the drawings and initially to  FIG. 1 , an exemplary heater valve  10  is shown. The heater valve includes a valve housing  12  having an inlet  14 , a first outlet  16  and a second outlet  18 . The inlet  14  is configured to receive an inlet port  20 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal, such as o-ring  24 . It will be appreciated, however, that the inlet port may be formed integrally with the housing. A locking ring  22  disposed around the inlet port  20  is provided to prevent loosening of the inlet port, and the locking ring may be secured to the housing by any suitable means, such as by threads. The inlet port  20  may be coupled to a supply line to receive fluid, such as high pressure hydraulic fluid from the supply line. Alternatively, the supply line may be directly coupled to the inlet. 
     The first outlet  16  is configured to receive a first outlet port  26 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal, such as o-ring  30 . It will be appreciated, however, that the first outlet port may be formed integrally with the housing. A locking ring  28  disposed around the outlet port  26  is provided to prevent loosening of the outlet port, and the locking ring may be secured to the housing by any suitable means, such as by threads. The first outlet port  26  receives fluid from the inlet port and may be coupled to a distribution line to deliver the fluid downstream of the valve  10 . Alternatively, the distribution line may be directly coupled to the first outlet. The second outlet  18  is configured to receive a second outlet port  32 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal, such as o-ring  34 . It will be appreciated, however, that the second outlet port may be formed integrally with the housing. The second outlet port  32  is configured to receive fluid from the inlet port and may be coupled to a fluid reservoir to deliver the fluid to the reservoir. Alternatively, the fluid reservoir may be directly coupled to the second outlet. 
     The valve  10  also includes a sleeve  42  assembled in the housing, which may alternatively be integrally formed with the housing, a thermal valve member  44  and a priority valve member  46 , the valve members being preferably in the form of spools guided in the sleeve and will herein be described as such. The sleeve  42  includes first openings  48  and second openings  50  connected by an annulus  52  and third openings  54  configured to communicate with an annulus  56  of the priority spool  46  and with a flow passage  58  in the housing. The sleeve is sealed to an inner wall of the housing  10  by suitable seals, such as o-ring  60  and back-up rings  62  and  64  at an upstream end of the sleeve, o-ring  66  and back-up rings  68  and  70  downstream of o-ring  60 , and o-ring  72  and back-up rings  74  and  76  downstream of o-ring  66 . The thermal spool  44  includes first openings  78  communicating with a passage  80  between the inlet and the first outlet, second openings  82  communicating with an annulus  83  on an outside of the thermal spool that communicates with the first openings  48  in the sleeve  42  when the thermal spool is in a first position, and a third opening  84  on a first end for receiving fluid. The thermal spool  44  also includes a hollow bore  86  allowing fluid to flow out of a second end of the thermal spool  44  to contact a pressure surface  88  of the priority spool  46 , which may be an end face. The pressure acting on the end face  88  can shift the priority spool  46  to a second position. 
     The thermal spool  44  is balanced by first and second springs  90  and  92 , which oppose one another and which may be concentrically arranged. The first spring  90  may be any suitable spring, such as a corrosion-resistant steel spring and the second spring  92  may be any suitable spring responsive to temperature changes of the fluid flowing through the housing, such as a nickel titanium (nitinol) spring. Alternatively, the first spring or both the first and second springs may be nickel titanium springs responsive to different temperatures. 
     The first spring  90  surrounds the thermal spool  44  and is interposed between a lip on the first end of the thermal spool  44  and an end wall of a counterbore of the sleeve  42 . The second spring  92  surrounds a thermal spring seat  94 , which has openings  96  and an opening  98  on a first end for receiving fluid. The second spring  90  is interposed between an end wall of a counterbore of a cap  100  and a lip of the spring seat  94 . When the valve  10  is assembled, the sleeve  42 , thermal spool  44  and priority spool  46  are inserted into the housing on a first side of the housing, with the spring  90  surrounding the thermal spool, and the thermal spring seat  94  is inserted over the thermal spool  44  so that a first end of the thermal spool abuts an end wall of a counterbore of the spring seat  94 . Alternatively, the priority spool can be inserted from a second side of the housing separately from the thermal spool and the sleeve. The cap  100  is then secured to the housing  12  by any suitable means, such as by retainer wire  102 , to hold the thermal spool  44 , spring  92  and spring seat  94  in place. The cap  100  is sealed to an inner wall of the housing  12  by suitable seals, such as o-ring  104  and back-up rings  106  and  108 . 
     The valve  10  also includes a third spring  110  biasing the priority spool in a first position, which as illustrated is a closed position. The spring  110  may be any suitable spring, such as a corrosion-resistant steel spring or a nickel titanium spring. The spring  110  is interposed between an end wall of a counterbore of a priority spring seat  112  and an end wall of a counterbore of the second outlet port  32 . The spring seat  112  includes openings  114  on a first end for receiving fluid that flows from a passage  116  to a passage  118  in the housing. 
     When fluid is flowing through the valve  10  from the inlet port  20  towards the first outlet port  26 , or from the first outlet port to the inlet port, the fluid flows over the thermal spool  44  and the thermal spring seat  94 . Some of the fluid enters the spring seat  94  via openings  96  and opening  98  and the thermal spool  44  via the first openings  78  and the third opening  84 , and some of the fluid flows out the first outlet port  26 . The fluid in the thermal spool  44  and spring seat  94  flows towards the second openings  82  in the thermal spool  44 . When the thermal spool is in the first position, as shown in  FIGS. 1 and 2  as an open position, the openings  82  and annulus  83  are aligned with the first openings  48  in the sleeve  42 . The fluid flows through the openings  48  towards the annulus  52  on an outside of the sleeve  42 . The fluid flows along the annulus  52  and into the sleeve  42  via the second openings  50 , and then through the sleeve along the annulus  56  on an outside of the priority spool  46 . When the priority spool  46  is in a second position, as shown in  FIGS. 2 and 3  as an open position, the fluid flows along the annulus  56  to the openings  54  in the sleeve  42 . The openings  54  are in line with the flow passage  58  in the housing. 
     Turning now to the operation of the valve  10 ,  FIG. 1  shows the thermal spool  44  in the first position and the priority spool  46  in the first position. The thermal spool  44  is in the first position when the temperature of the fluid is below a predetermined temperature, for example, less than twenty degrees Celsius, and the priority spool  46  is in the first position when the pressure of the fluid is below a predetermined pressure, for example, less than 250 bar. When the temperature is below the predetermined temperature, the spring force of the first spring  90  is greater than the spring force of the second spring  92 , thereby causing the thermal spool  44  to be shifted to the first position by the first spring  90 . 
     As mentioned above, as the fluid flows over thermal spool  44 , spring seat  94 , and first and second springs  90  and  92 , some of the fluid enters the thermal spool  44  and spring seat  94  via the openings  78 ,  84 ,  96  and  98 . The fluid flows towards the second end of the thermal spool  44  and exits the spool via openings  82  and the annulus  83 , which are aligned with the first openings  48  in the sleeve  42 . The fluid flows from the first openings  48  to the annulus  52  and then along the annulus to the second openings  50  in the sleeve  42 . The fluid then flows from the openings  50  to the annulus  56  on the priority spool  46  and along the annulus. However, because the pressure of the fluid is below the predetermined pressure, the priority spool  46  is in the first position and the annulus  56  is not aligned with the openings  54  in the sleeve. Therefore, the fluid does not enter the flow passage  58  and only exits the valve  10  via the first outlet port  26 . 
     Turning now to the operation of the valve  10  shown in  FIG. 2 , the thermal spool  44  is shown in the first position and the priority spool  46  is shown in the second position. The priority spool  46  is in the second position when the pressure of the fluid is above the predetermined pressure, for example, greater than 250 bar. The priority spool  46  is moved to the second position by the fluid flowing through the bore  86  of the thermal spool  44 . When the pressure of the fluid entering the valve  10  is above the predetermined pressure, the pressure of the fluid flowing through the bore  86  acts on the end face  88  to shift the priority spool  46  towards the second outlet port  32  to the second position so that the annulus  56  is aligned with the openings  54 . The priority spool  46  therefore overcomes the spring force of the spring  110  that is biasing the priority spool  46  in the first position, and the fluid flows from the openings  54  to the flow passage  58 . 
     The fluid then flows from the flow passage  58  to a heating orifice  120 , where the fluid will increase in temperature and experience a pressure drop. The now low pressure, high temperature fluid exits the heating orifice  120  and flows to the flow passage  116  and then to the passage  118 . The fluid enters the passage  118  and flows around the priority spring seat  112  and into the spring seat via openings  114  on the first end of the spring seat. The fluid then flows through the spring seat  112  and out the second outlet port  32  to a fluid reservoir. Accordingly, as shown in  FIG. 2 , fluid having a temperature below the predetermined temperature and a pressure above the predetermined pressure flows out the first outlet port  26 , while fluid having a temperature above the predetermined temperature and a pressure below the predetermined pressure flows out the second outlet port  32 . In this way, high temperature fluid can be returned to the reservoir via the second outlet port so that when the fluid is re-circulated through the valve  10 , the fluid has a higher temperature and therefore prevents or reduces pressure drops downstream of the valve  10 . With pressure drops being prevented or reduced, smaller hydraulic lines may be used in the airplane, thereby reducing the weight of the airplane. Moreover, because the fluid flowing through the lines will be at a higher temperature, the valve allows for faster response of flight control actuators on the aircraft. 
     Turning now to  FIG. 3 , the thermal spool  44  is shown in a second position and the priority spool  46  is shown in the second position. The thermal spool  44  is in the second position, which as shown is a closed position, when the temperature of the fluid is above the predetermined temperature, for example, greater than thirty degrees Celsius. If the thermal spool is configured to be in the first position at a first temperature and a second position at a second temperature (for example, if the thermal spool is in the first position at a temperature less than twenty degrees Celsius and the second position at a temperature greater than thirty degrees Celsius), the thermal spool may be in a partially open/closed position between the two temperatures. 
     As the fluid at a temperature above the predetermined temperature flows over the first and second springs  90  and  92 , the second spring  92  reacts to the temperature of the fluid and the spring force of the second spring  92  increases to a spring force greater than the spring force of the first spring  90 . The second spring  92  then shifts the thermal spool  44  to the second position towards the priority spool  46 . In the second position, the second openings  82  and annulus  83  in the thermal spool  44  no longer are aligned with the openings  50  in the sleeve  42 . Therefore, even though the pressure of the fluid is above the predetermined pressure, resulting in the priority spool  46  being in the second position so that the annulus  56  is aligned with the openings  54 , the fluid does not flow to the annulus  56 . Accordingly, the fluid does not enter the flow passage  58  and therefore only exits the valve  10  via the first outlet port  26 . 
     Referring now to  FIGS. 4 and 5 , another embodiment of the heater valve according to the invention is indicated generally by reference numeral  150 . The heater valve  150  is substantially the same as the above-referenced heater valve  10 , and accordingly, the foregoing description of the heater valve  10  is equally applicable to the heater valve  150  except as noted below. 
     The heater valve includes a housing  152  having an inlet  154 , a first outlet  156  and a second outlet  158 . The inlet  154  is configured to receive an inlet port  160 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal. It will be appreciated, however, that the inlet port may be formed integrally with the housing. A locking ring  162  disposed around the inlet port  160 , and the locking ring may be secured to the housing by any suitable means, such as by threads. The first outlet  156  is configured to receive a first outlet port  164 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal. It will be appreciated, however, that the first outlet port may be formed integrally with the housing. A locking ring  166  disposed around the outlet port  164  is provided to prevent loosening of the outlet port, and the locking ring may be secured to the housing by any suitable means, such as by threads. The second outlet  158  is configured to receive a second outlet port  168 , which is secured to the housing by any suitable means, such as by threads, and sealed by a suitable seal, such as o-ring  170 . It will be appreciated, however, that the second outlet port may be formed integrally with the housing. 
     The valve  150  also includes sleeve  174 , which may be integrally formed with the housing, a thermal valve member  176  and a priority valve member  178 , the valve members being preferably in the form of spools guided in the sleeve and will herein be described as such. The sleeve  174  includes first openings  180  and second openings  182  connected by an annulus  184  and third openings  186  configured to communicate with an annulus  188  of the priority spool  178  and with a flow passage  190  in the housing. The sleeve  174  is sealed to an inner wall of the housing  150  by suitable seals, such as o-ring  192  and back-up rings  193  and  194  at an upstream end of the sleeve, o-ring  196  and back-up rings  198  and  200  downstream of o-ring  192 , and o-ring  202  and back-up rings  204  and  206  downstream of o-ring  196 . The thermal spool  176  includes first openings  208  communicating with a passage  210  between the inlet and the first outlet, second openings  212  communicating with an annulus  213  on an outside of the thermal spool that communicates with the first openings  180  in the sleeve  174  when the thermal spool is in a first position, and a third opening  214  for receiving fluid. The thermal spool  174  also includes a hollow bore  216  allowing fluid to flow through the thermal spool to contact a pressure surface  218  of the priority spool  178 , which may be an end face. The pressure acting on the end face  218  can shift the priority spool  178  to a second position. 
     The thermal spool  176  is balanced by first and second springs  220  and  222 , which oppose one another and which may be concentrically arranged. The first spring  220  may be any suitable spring, such as a corrosion-resistant steel spring and the second spring  222  may be any suitable spring responsive to temperature changes of the fluid flowing through the housing, such as a nickel titanium (nitinol) spring. Alternatively, the first spring or both the first and second springs may be nickel titanium springs responsive to different temperatures. 
     The first spring  220  surrounds a thermal spring seat  224 , which has openings  226  and an opening  228  on a first end for receiving fluid. The spring  220  is interposed between lip of the spring seat  224  and a retaining ring  230 . The retainer ring  230  has an opening through which the thermal spool is inserted and is disposed upstream of the lip of the spring seat  224  and adjacent a first end of the sleeve  174 . The second spring  222  is interposed between an end wall of a counterbore of a cap  232  and a washer  234  disposed on an end wall of a counterbore of the spring seat  224 . The washer has an opening  235  through which fluid flows and the thermal spool  178  is mechanically interlocked into the sleeve  174  via the washer  234 . When the valve  150  is assembled, the sleeve  174  and priority spool  178  are inserted into the valve housing  152  on a first side of the housing. Alternatively, the priority spool can be inserted from a second side of the housing. The retaining ring  230  and the first spring  220  are then inserted into the housing. The thermal spool  176  and washer  234  are inserted into the spring seat  224 , before being inserted into the housing, and the spring seat  224  is inserted so that the lip on the spring seat abuts the first end of the spring  220 . The second spring  222  can then be inserted into the spring seat, or alternatively already be disposed in the spring seat, and the cap  232  secured to the housing  152  by any suitable means, such as threads. The cap  232  is sealed to an inner wall of the housing  152  by suitable seals, such as o-ring  236  and back-up ring  238 . 
     The valve  150  also includes a third spring  240  biasing the priority spool in a first position, which as illustrated is a closed position. The spring  240  may be any suitable spring, such as a corrosion-resistant steel spring or a nickel titanium spring. The spring  240  is interposed between an end wall of a counterbore of a priority spring seat  242  and an end wall of a counterbore of the second outlet port  168 . The spring seat  242  includes openings  244  ( FIG. 6 ) on a first end for receiving fluid that flows from a passage  246  to a passage  248  in the housing. 
     When fluid is flowing through the valve  150  from the inlet port  160  towards the first outlet port  164 , or from the first outlet port to the inlet port, the fluid flows over the thermal spool  176  and the thermal spring seat  224 . Some of the fluid enters the spring seat  224  via openings  226  and opening  228  and the thermal spool  176  via the first openings  208  and the third opening  214 . The fluid in the thermal spool  176  and spring seat  224  flows towards the second openings  212  in the thermal spool. When the thermal spool  176  is in the first position, as shown in  FIGS. 4 and 5  as an open position, the openings  212  and annulus  213  are aligned with the first openings  180  in the sleeve  174 . The fluid flows through the openings  180  towards the annulus  184  on an outside of the sleeve  174 . The fluid flows along the annulus  184  and into the sleeve  174  via the second openings  182 , and then though the sleeve along the annulus  188  on an outside of the priority spool  178 . 
     When the priority spool  178  is in a second position, which is an open position similar to  FIGS. 2 and 3 , the fluid flows along the annulus  188  to the openings  186  in the sleeve  174  and then to the flow passage  190  and out the second outlet  168 . The priority spool is moved to the second position by the fluid flowing through the bore  216  of the thermal spool. When the pressure of the fluid entering the valve  150  is above the predetermined pressure, the pressure of the fluid flowing through the bore  216  acts on the end face  218  of the priority spool  178  to shift the priority spool to the second position so that the annulus  188  is aligned with the openings  186 . The fluid then flows from the flow passage  190  to a heating orifice  250 , where the fluid will increase in temperature and experience a pressure drop. The low pressure, high temperature fluid exiting the heating orifice then flows to the flow passage  246  that communicates with the passage  248  in the housing  152 . The fluid enters the passage  248  and flows around the priority spring seat  242  via grooves  252 , shown in  FIG. 6 , on an outer surface of the spring seat. The fluid can flow into the spring seat via openings  244 , shown in  FIG. 6 , on a first end of the spring seat, and can also flow along the grooves  252  towards the second outlet port  168 . The fluid then flow around and through the spring seat  242 , and out of the second outlet port  168  to a fluid reservoir. Accordingly, the fluid flows out of the valve  150  via both outlet ports  164  and  168 . 
     As best shown in  FIG. 5 , the heater valve  150  also includes a pressure sensor  256 , which may be a pressure switch. The pressure sensor is provided to sense the pressure in a passage downstream of the thermal valve. The pressure sensor can therefore determine when both the thermal spool  176  and the priority spool  178  are open to detect when the heater valve  150  is heating fluid and when the valve is not heating fluid. The housing includes an opening  258  configured to receive a first end of the pressure sensor  256 . The pressure sensor is held in place by a collar  260  and sealed by suitable seals, such as o-ring  262  and back-up rings  264  and  266 . The collar  260  is secured to the housing by any suitable means, such as by threads. A second end of the pressure switch is configured to be coupled to the aircraft so that the pressure switch can be connected to an aircraft signal wire. 
     Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.