Patent Abstract:
A valve for regulating fluid flow and associated method of use. The valve includes a stepper motor, a first valve chamber having an inlet port, a second valve chamber having an outlet port, wherein the first valve chamber includes an opening between the first valve chamber and the second valve chamber, a first member that is rotatable and operatively attached to the stepper motor, a second member that engages the first member for linear movement of the second member between a first position and a second position when the first member is rotated by the stepper motor, and a sealing mechanism that is operatively attached to the second member, wherein the sealing mechanism can move adjacent to the opening when the second member is in the first position and the sealing mechanism can move away from the opening when the second member is in the second position.

Full Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This patent application claims priority to U.S. Provisional Patent Application Ser. No. 60/465,616 filed Apr. 24, 2003. 
     
    
     
       BACKGROUND OF INVENTION  
         [0002]    In many cooling systems associated with internal combustion engines, there is a requirement to control the flow of coolant in either a bypass loop or control the flow of coolant that goes into a core for a heater. This coolant flow control is currently performed with any of four (4) primary valve structures that can be driven by any one of five (5) valve control mechanisms.  
           [0003]    In circumstances where the flow of coolant in either the bypass loop or the heater valve only needs to be turned on or turned off, a butterfly valve, a barrel valve, a poppet valve or a gate valve is typically utilized. However, when a variable flow of coolant in either the bypass loop or the heater valve is required, then only a barrel valve or a gate valve is utilized. There are five (5) mechanisms or techniques for operating the valves used in regulating the flow of coolant in either the bypass loop or the heater valve. The first mechanism is a direct mechanical linkage that is manually operated by the driver of the vehicle from the passenger compartment. The second mechanism is a blend door actuator that opens or closes a valve that is driven by a mechanical linkage. The blend door actuator functions much like an electronic temperature control system and controls the temperature. The blend door actuator controls the heat/cooling by monitoring a feedback signal from the temperature selector and electrically adjusts the blend door by means of an electric motor connected to a mechanical linkage to satisfy the request. The third mechanism is an auxiliary vacuum actuator that can position a valve in either two or three positions. The fourth mechanism utilizes a direct current (DC) motor and gear train with a feedback mechanism to indicate the variable position of a valve. Finally, the fifth mechanism is to use a direct solenoid drive to open and close a valve. This is utilized almost exclusively with poppet-type valves.  
           [0004]    There are a number of limitations with these valves and valve control mechanisms. One significant limitation is that these valves need to be able to precisely control coolant flow in low flow ranges as well as being able to open fully to minimize pressure drop when full flow conditions are required. Poppet valves and butterfly valves provide a significant disadvantage regarding pressure drop since their flow control members remain in the flow path during full flow conditions. Barrel valves are typically used for variable flow, however, due to the geometric limitations of the barrel valve, the limited flow metering capability of the barrel valve is often gained at the expense of having adequate overall coolant flow through the barrel valve. Although gate valves can provide fine metered flow and do provide minimal pressure drop at full flow conditions, there are significant problems in size that restrict implementation in an automotive/vehicle coolant system.  
           [0005]    Each one of the previously described valve control mechanisms has significant disadvantages. The direct mechanical linkage does not provide direct control of the valve in relation to the other heating, ventilating and air conditioning (HVAC) components in the vehicle. The indirect control of the valve via the blend door actuator also does not provide direct control of the valve in relation to the other heating, ventilating and air conditioning (HVAC) components in the vehicle. The auxiliary vacuum actuator is limited to two (2) or three (3) positions. This is of very limited value in a coolant flow control application. The direct current (DC) motor and gear train require auxiliary feedback electronics. This typically includes a potentiometer and onboard electronics to control position of the valve. This type of feedback circuit can be expensive and prone to problems due to the heat and other environmental factors associated with the vehicle. A direct solenoid control limits the valve to a two (2) position device. In order to provide flow control, the solenoid control needs to be pulsed on and off. This can create the undesirable effect of “hammering.” Hammering is a phenomenon that may cause damage to a valve or cause it to fail in delivering its main function. The unstable opening and closing of a valve reveals a shortcoming in the ability to maintain constant coolant flow velocity and effective closing. Solenoid controls also have the very undesirable effect of drawing a large amount of current.  
           [0006]    In many situations when the internal combustion engine is cooling, it is desirable for the valve to return to a full open (fail-safe) position when the operating signal to the valve is lost. Universally, all valves that are operated by a mechanical linkage fail to have this type of feature. Electrically actuated valves that are driven by a direct current (DC) motor and a gear train require an external spring or possibly a clutch mechanism to accomplish this task. Both of these additional components are undesirable since both components can fail and are difficult to replace.  
           [0007]    The present invention is directed to overcoming one or more of the problems set forth above.  
         SUMMARY OF INVENTION  
         [0008]    In one aspect of this invention, a valve for regulating fluid flow is disclosed. This valve includes a stepper motor, a first valve chamber having an inlet port for receiving fluid into the valve, a second valve chamber having an outlet port for dispensing fluid from the valve, wherein the first valve chamber includes an opening between the first valve chamber and the second valve chamber, a first member that is rotatable and operatively attached to the stepper motor, a second member that engages the first member for linear movement of the second member between a first position and a second position when the first member is rotated by the stepper motor, and a sealing mechanism that is operatively attached to the second member, wherein the sealing mechanism can move adjacent to the opening when the second member is in the first position and the sealing mechanism can move away from the opening when the second member is in the second position.  
           [0009]    In another aspect of this invention, a method for regulating fluid flow with a valve is disclosed. This method includes rotating a first member that is operatively attached to a stepper motor within a valve, wherein the valve includes a first valve chamber having an inlet port for receiving fluid into the valve and a second valve chamber having an outlet port for dispensing fluid from the valve and the first valve chamber includes an opening between the first valve chamber and the second valve chamber, moving a second member that engages the first member between a first position and a second position when the first member is rotated by the stepper motor, moving a sealing mechanism that is operatively attached to the second adjacent to the opening when the second member is in the first position, and moving the sealing mechanism away from the opening when the second member is in the second position.  
           [0010]    These are merely some of the innumerable aspects of the present invention and should not be deemed an all-inclusive listing of the innumerable aspects associated with the present invention. These and other aspects will become apparent to those skilled in the art in light of the following disclosure and accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    For a better understanding of the present invention, reference may be made to the accompanying drawings in which:  
         [0012]    [0012]FIG. 1 is a cross-sectional view of a stepper motor driven coolant valve for delivering coolant in accordance with the present invention in an open position;  
         [0013]    [0013]FIG. 2 is a cross-sectional view of the stepper motor driven coolant valve, as shown in FIG. 1, for delivering coolant in accordance with the present invention in a fully closed position;  
         [0014]    [0014]FIG. 3 is an isolated perspective view of a metering orifice, shown in FIGS. 1 and 2, utilized with the stepper motor driven coolant valve for delivering coolant in accordance with the present invention;  
         [0015]    [0015]FIG. 4 is a sectional view of the stepper motor driven valve, taken along Line C-C in FIG. 2, in accordance with the present invention;  
         [0016]    [0016]FIG. 5 is an exploded view of the stepper motor driven coolant valve, as shown in FIG. 1, for delivering coolant in accordance with the present invention;  
         [0017]    [0017]FIG. 6 is a basic schematic of a fluid, e.g., coolant, system for a vehicle that illustrates an engine, a radiator, a pump, a thermostat and a bypass loop where fluid, e.g., coolant, flow through the bypass loop is controlled by the valve of the present invention; and  
         [0018]    [0018]FIG. 7 is a basic schematic of a fluid, e.g., coolant, system for a vehicle that illustrates an engine, a radiator, a pump, a heater core and a bypass loop where fluid, e.g., coolant, flow through the heater core is controlled by the valve of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as to obscure the present invention. For example, the invention can be applied to virtually any type of device that can benefit from controlled fluid flow throughout a range of fluid flow. Moreover, this invention can be applied to virtually any type of motorized vehicle that utilizes fluid as a coolant for reducing heat in an engine, e.g., internal combustion engine. The fluid is preferably coolant; however, a wide range of fluids may suffice.  
         [0020]    Referring now to the drawings, and initially to FIGS. 1, 2 and  4 , where a valve that is utilized to control fluid, e.g., coolant, flow, is generally indicated by numeral  2 . The valve  2  is shown in a default or unpowered position in FIG. 1. There is a biasing mechanism  4 , which is preferably, but not necessarily, in the form of a return spring. The biasing mechanism  4  if in the form of a return spring is preferably spiral and supported by a ledge  80  in a valve body  32  for the valve  2 . The biasing mechanism  4  applies a load to a needle  6 . This needle  6  is preferably, but not necessarily, aligned with a vertical axis or centerline  3  for the valve  2 . The needle  6  preferably includes a plurality of female threads or indentations  8  that are integrally formed and located therein that are capable of mating with a plurality of male protrusions or threads  10  in a screw  12 . Due to the force of the biasing mechanism, e.g., return spring,  4  there are both translational and rotational loads applied to the needle  6 . Therefore, when the screw  12  rotates, the plurality of male protrusions or threads  10  engage the plurality of the female threads or indentations  8  for the needle  6  so that the needle  6  can move up or down along the vertical axis or centerline  3  depending on the direction of rotation of the screw  12 . The screw  12  is operatively connected to a stepper motor  16 . Preferably, the screw  12  is mechanically connected with hardware to the stepper motor  16 ; however, attachment by adhesives, thermal bonding and other methods will suffice. The preferred hardware is a connecting sleeve portion  18 , which is preferably, but not necessarily, part of the screw  12 , which connects to the rotor  20  for the stepper motor  16 , as shown in FIGS. 5-7. An illustrative, but nonlimiting, example of a stepper motor  16  includes SKC Motor Number XE-2002-0962-00 manufactured by Shinano Kenshi Corp., having a place of business at 5737 Mesmer Avenue, Culver City, Calif. 90230. However, a wide variety of stepper motors  16  will suffice for the present invention.  
         [0021]    A wide variety of materials can be utilized for the main components of the valve  2  with the exception of the stepper motor  16  and fluid sealing mechanisms. One illustrative, but nonlimiting, example includes 1503-2 grade of resin that includes nylon 6/6 that is glass reinforced. This 1503-2 grade of resin is manufactured by TICONA®, having a place of business at 90 Morris Avenue, Summit, N.J. 07901. However, a wide variety of other materials will suffice for this application. One illustrative, but nonlimiting, example of material for the plunger  6  includes an acetal copolymer. An acetal copolymer is a polyoxymethylene (POM) with a high crystallinity delivering high strength, stiffness, toughness, and lubricity over a broad range of temperatures and chemical environments. Acetal copolymers can be processed by many conventional means including injection molding, blow molding, extrusion and rotational casting. One illustrative, but nonlimiting, example of material for the screw  12  includes nylon 6 combined with polytetrafluoroethylene (PTFE) to reduce friction.  
         [0022]    A feature of this valve  2  is the force balance between the stepper motor  16  and the biasing mechanism, e.g., return spring,  4 . This valve  2  is designed so that when an appropriate signal is provided to the stepper motor  16 , there is sufficient force to turn the screw  12  that moves the needle  6  to compress the biasing mechanism, e.g., return spring,  4  and close the valve  2 . Conversely, there must be enough force in the biasing mechanism, e.g., return spring,  4  to turn the screw  12  to move the needle  6  that rotates the stepper motor  16  when power is removed from the stepper motor  16  to open the valve  2 . The construction and design of the biasing mechanism, e.g., return spring,  4  can vary greatly to comport with the wide variety of stepper motors utilized to create to balance the force. Therefore, a feature of this invention is the ability for the valve  2  to go to a full open position as a failsafe when power is removed from the stepper motor  16 .  
         [0023]    As shown in FIGS. 1 and 2, and as best shown in FIG. 5, the stepper motor  16  includes a protective outer housing end cap  26  that covers the outer top portion of the stepper motor  16 . As shown in FIG. 5, there is a gasket  27  having an electrical terminal connector  28  to provide electrical connections to the terminals (not shown) on the stepper motor  16 . This electrical terminal connector  28  provides a simple electrical interface that can be easily connected to other components in an electrical control system.  
         [0024]    Located below the stepper motor  16  is a valve body  32 . There is a cover member  30  that includes a protruding member  36  that is preferably an integral portion but can be a separate part attached thereto, as shown in FIGS. 1, 2,  4  and  5 . The cover member  30  is preferably, but not necessarily, made of resilient material with a series of protruding threads  34  to seal the cover member  30  to the valve body  32 , as shown in FIG. 5. There is a first o-ring  38  located between the cover member  30  and the valve body  32  and a second o-ring  40  between the sleeve  18  and the cover member  18  to prevent fluid from leaving the valve body  32 . An illustrative, but nonlimiting material for the o-rings  38  and  40 , respectively, can include Nitrile/Buna-N type of material as well as EPDM for use at higher temperatures.  
         [0025]    There is a poppet  42  that is attached to the needle  6 . The poppet  42  includes an outer flange portion  44  that extends downward therefrom. The poppet  42  moves up and down with the needle  6 . The valve body  32  includes an inlet port  46  for receiving fluid and an outlet port  48  for releasing fluid. There is a middle opening  50  located between the inlet port  46  and the outlet port  48  that separates the valve  2  into a first chamber  54  and a second chamber  56  to provide a two stage valve structure. As shown in FIG. 1, when the valve  2  is open, the needle  6  is near the stepper motor  16  and the poppet  42  is raised to allow fluid to flow between the inlet port  46  and the outlet port  48  through the middle opening  50 . The poppet  42  is preferably manufactured of resilient material, e.g., quality synthetic rubber (QSR). Preferably, there is a washer  52  located underneath the poppet  42  within the outer flange portion to enhance sealing and prevent fluid flow when the valve  2  is closed. The washer  52  is preferably made of metal, e.g., brass, to provide strength and rigidity to the poppet  42 . There is a retainer  77  that provides support for the poppet  42  so that the pressure of the biasing mechanism, e.g., return spring, does not put too much pressure on the center of the poppet  42  so that the relative horizontal position of the poppet  42  in relationship to the vertical axis or centerline  3  can be maintained. A wide variety of materials may suffice but the more rigid materials are preferred such as those utilized with the needle  6  or the screw  12 .  
         [0026]    As shown in FIG. 2, when the valve  2  is closed, the needle  6  is as far removed from the stepper motor  16  as possible and the poppet  42  is flush against the middle opening  50  to prevent the passage of fluid from the inlet port  46  to the outlet port  48 . The pressure in the first chamber  54  is generally higher than the pressure in the second chamber  56 . This creates a differential pressure due to this pressure drop across the valve  2  that adds a downward force against both the needle  6  and the poppet  42 . Since the needle  6  has only a small percentage of the cross-sectional area of the poppet  42 , the biasing mechanism, e.g., return spring,  4  requires a much lower force to move the needle  6  then if the valve  2  had only a single stage or chamber. As shown in FIG. 3, once the needle  6  starts to move, there is a metering orifice  58  that is present on the needle that allows the pressure to balance between the first chamber  54  and the second chamber  56 . This allows the biasing mechanism, e.g., return spring,  4  to have enough force to lift the outer flange portion  44  of the poppet  42  from a valve seat  43  to completely open the valve  2 , as shown in FIG. 1.  
         [0027]    Under normal operating conditions, the stepper motor  16  will be powered to rotate the screw  12  in either a clockwise or counterclockwise direction to move the needle  6  either up or down. There are two operation conditions. The first condition is the full opening region. The full opening region is from when the needle  6  is as close as possible to the stepper motor  16  to being extended to the point where the poppet  42  is still far enough away from the valve seat  43  to allow full fluid flow. The range of travel for the needle  6  from the stepper motor  16  is from about zero percent (0%) to about one hundred percent (100%), and preferably from about twenty percent (20%) to about sixty percent (60%) and optimally about forty percent (40%). There is a low-pressure differential or drop between the first chamber  54  and the second chamber  56 , which is an advantageous aspect of the present invention.  
         [0028]    The second operating condition is when the outer flange portion  44  of the poppet  42  is in full contact with the valve seat  43 . At this point, there is relative motion between the poppet  42  and the needle  6  with all fluid flow is through the metering orifice  58 , as shown in FIG. 3. The metering orifice is preferably, but not necessarily, tapered or triangular to precisely control the flow of fluid and allow very little fluid flow at a top portion  60  of the needle  6  and maximum flow at a bottom portion  62  of the needle  6 . This provides precise metering at low fluid flow conditions, which is an advantage of the present invention The metering orifice can literally have any geometric configuration depending on the change in the rate of fluid flow that is desired.  
         [0029]    The degrees of rotation for the stepper motor  16  can range from about zero (0) degrees per step to about one hundred and eighty (180) degrees per step and preferably from about twenty (20) degrees per step to about fifty (50) degrees per step and optimally about 1.8 degrees per step. The pitch of the screw  12  can range from about two (2) male protrusions or threads  10  per inch to about fifty (50) male protrusions or threads  10  per inch and preferably from about three (3) male protrusions or threads  10  per inch to about eight (8) male protrusions or threads  10  per inch and optimally about five (5) male protrusions or threads  10  per inch. Therefore, the needle  6  can travel from about 10 inches per step to about 0.000001 inches per step and preferably from about 0.01 inches per step to about 0.001 inches per step and optimally about 0.001 inches per step. As an illustrative example, at 1.8 degrees per step with the pitch of the screw  12  at five (5) male protrusions or threads  10  per inch and the needle  6  travelling 0.001 inches per step, results in 500 steps for the needle  6  to travel one-half (0.5) inch for very precise flow control.  
         [0030]    The valve  2  relies on differential pressure between the first chamber  54  and the second chamber  56  for sealing the poppet  42  against the valve seat  43 . When there is zero (0) differential pressure between the two chambers  54  and  56 , there is a need to correct the staging for the valve  2 . As shown in FIG. 2, when the valve  2  is in the full closed position and there is zero differential fluid pressure between the first chamber  54  and the second chamber  56 , the relative motion between the poppet  42  and the needle  6  will not occur as intended with the outer flange portion  44  of the poppet  42  lifting away from the valve seat  43 . From a sealing perspective, this is irrelevant since the fact that the differential pressure between the first chamber  54  and the second chamber  56  means that there is zero (0) flow of fluid. However, it is important that the valve  2  be in position or reset for the next stroke. This is accomplished by having the protruding member  36  for the cover member  30  force the poppet  42  to the default position, as shown in FIG. 1, whenever the valve  2  is in a full open position or default position. The aspect of providing a failsafe to a full open position for the valve  2  as a default is an advantage of the present invention.  
         [0031]    As shown in FIG. 4, the cover member  30  includes a protruding member  36 . There are preferably at least two retaining guide members  121  and  123  located on the needle  6 . The protruding member  36  is positioned between the retaining guide members  121  and  123 . This provides an anti-rotational feature so that the needle  6  only translates force along the centerline  3  of the valve  2 .  
         [0032]    Referring now to FIG. 6, as an illustrative, but nonlimiting application, the valve  2  can be utilized to control fluid, e.g., coolant, flow through the bypass loop  133  from the engine  127  from a first fluid conduit  137 . When the standard thermostat  125  has not reached the set point temperature, all flow of fluid e.g., coolant, flow from the fluid pump  129  will go through a second fluid conduit  143  and into the engine  127 . From the engine  127 , fluid will flow into the bypass loop  133  via the first fluid conduit  137  and then back into the fluid pump  129 . By controlling the amount of fluid flow in the bypass loop  133 , the engine  127  can run hotter with greater fuel efficiency and reduced emissions. The valve  2  can be operated from sensor data from a processor (not shown) to maximize performance of the engine  127 . Preferably, look-up tables can be utilized in conjunction with the sensor data. This will control the temperature of the engine  127  through a complete range of fluid flow until the set point temperature of the thermostat  125  is reached. At this point, the valve  2  can be operated in conjunction with the thermostat  125  to accurately control the temperature of the engine  127  with fluid going through the thermostat  125  via the first fluid conduit  137  and into a radiator  131  via a third fluid conduit  139 . From the radiator  131 , fluid goes back into the inlet for the fluid pump  129  via a fourth fluid conduit  141 .  
         [0033]    Referring now to FIG. 7, as another illustrative but nonlimiting application, the valve  2  can be utilized to control heated fluid, e.g., coolant, flow from the engine  127  via a fifth fluid conduit  151  into the inlet port  46  of the valve  2  and out through the outlet port  48  and into a heater core  160  via a sixth fluid conduit  152 . The fluid, e.g., coolant, then leaves the heater core  160  via a seventh fluid conduit  154  and returns to the fluid pump  129 . The remainder of the system is as described previously, with a bypass loop  133  from the engine  127  from a first fluid conduit  137 . When the standard thermostat  125  has not reached the set point temperature, all flow of fluid e.g., coolant, flow from the fluid pump  129  is through a second fluid conduit  143  into the engine  127 . From the engine  127 , the fluid flows into the bypass loop  133  via the first fluid conduit  137  and then back into the fluid pump  129 .  
         [0034]    The valve  2  can be operated from sensor data from a processor (not shown) to maximize performance of the heater core  160 . Preferably look-up tables can be utilized in conjunction with the sensor data. This will provide some control over the temperature of the heater core  160 . When the set point temperature of the thermostat  125  is reached, the valve  2  can be operated in conjunction with the thermostat  125  to accurately control the temperature of the engine  127  with fluid going through the thermostat  125  via the first fluid conduit  137  and into a radiator  131  via a third fluid conduit  139 . From the radiator  131  fluid goes back into the inlet for the fluid pump  129  via a fourth fluid conduit  141  and then is pumped back into the engine  127  via the second fluid conduit  143 .  
         [0035]    Although the preferred embodiment of the present invention and the method of using the same has been described in the foregoing specification with considerable details, it is to be understood that modifications may be made to the invention, which do not exceed the scope of the appended claims and modified forms of the present invention done by others skilled in the art to which the invention pertains will be considered infringements of this invention when those modified forms fall within the claimed scope of this invention.

Technology Classification (CPC): 5