Patent Publication Number: US-8539978-B2

Title: Gas valve unit with bypass flow

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to systems for control of a gas fired appliance having a gas valve, and more particularly relates to gas valves for control of gas flow to such an appliance. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
     Gas-fired heating units or furnaces that operate at two or more gas flow rates are generally referred to as multistage furnaces. Multistage furnaces are frequently selected by homeowners over single stage furnaces because they offer increased performance and comfort by varying the level of heating output as needed. In many multistage furnaces, a furnace control may be configured to request operation of a gas valve at a desired operating capacity level or gas flow rate. The operating capacity level requested by such furnace controls could be as low as 30 percent of full capacity gas flow operation. However, at low capacity gas flow rates, such gas valves are not capable of controllably maintaining the gas flow rate within a desired tolerance, and therefore are not utilized at such low capacity levels. Accordingly, a need still exists for an improved valve unit and associated control for present two stage heating systems. 
     SUMMARY 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     Various embodiments are provided of a valve unit for a heating or combustion apparatus. One embodiment of a valve unit includes a valve member that moves relative to a valve seat in response to a signal input to a coil, for varying a high-capacity gas flow rate through the valve unit. The valve unit includes a first opening port, a second opening port that is smaller than the first opening port, and a closure member. The closure member is movable between an open position, in which said high-capacity gas flow rate is communicated via the first and second opening ports to at least one outlet, and a closed position against the first opening port, in which a low-capacity gas flow rate is communicated via only the second opening port to the at least one outlet. The valve unit includes a solenoid for selectively moving the closure member between the open and closed positions, to respectively selectively establish a high-capacity gas flow rate or low capacity gas flow rate to at least one outlet. 
     According to another aspect of the present disclosure, various embodiments of a valve unit are provided that are configured to control the signal that is input to the coil to adjust the gas flow rate through the valve seat to a desired gas flow rate. In some embodiments, the coil is part of a stepper-motor that displaces the valve member based on an input voltage applied to the stepper-motor coil, where the valve member is configured to displace a diaphragm to vary the gas flow rate through the valve unit. In other embodiments, the coil is a solenoid coil that is configured to move the valve member to vary the high-capacity gas flow rate based on the magnetic field generated by the coil, where the magnetic field is dependent on the input voltage. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples provided in this summary are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  depicts a schematic diagram of a variable heating system controller, shown within a heating apparatus that includes a valve unit; 
         FIG. 2  shows a cross-sectional view of a first embodiment of a valve unit for controlling gas flow within a heating apparatus; 
         FIG. 3  shows a cross-sectional view of an alternate construction of the first embodiment of a valve unit shown in  FIG. 2 ; 
         FIG. 4  shows a cross-sectional view of a second embodiment of a valve unit for controlling gas flow within a heating apparatus; and 
         FIG. 5  shows a schematic diagram of a valve controller, according to the principles of the present disclosure. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     Various embodiments are provided of a valve unit for a heating or combustion apparatus. One embodiment of a valve unit includes a valve member that moves relative to a valve seat in response to a signal input to a coil, for varying a high-capacity gas flow rate through the valve unit. The valve unit includes a first opening port, a second opening port that is smaller than the first opening port, and a closure member. The closure member is movable between an open position, in which said high-capacity gas flow rate is communicated via the first and second opening ports to an outlet, and a closed position against the first opening port, in which a low-capacity gas flow rate is communicated via only the second opening port to the outlet. The valve unit includes a solenoid for selectively moving the closure member between the open position and closed position to selectively establish a high-capacity gas flow rate or low capacity gas flow rate, respectively, to the outlet. 
     According to another aspect of the present disclosure, various embodiments of a valve unit are provided that are configured to control the signal that is input to the coil to adjust the gas flow rate through the valve seat to a desired gas flow rate. In some embodiments, the coil is part of a stepper-motor that displaces the valve member based on an input voltage applied to the stepper-motor coil, where the valve member is configured to displace a diaphragm to vary the gas flow rate through the valve unit. In other embodiments, the coil is a solenoid coil that is configured to move the valve member to vary the high-capacity gas flow rate based on the magnetic field generated by the coil, where the magnetic field is dependent on the input voltage. 
     The various embodiments of a valve unit are connectable to and operable with a variable heating system controller for a furnace or heating unit, where the variable-heating system controller initiates operation of the heating unit based on input signals from a single-stage, two-stage or other type of thermostat. To better illustrate the operation of the valve unit embodiments, an example of a variable-heating system controller for a heating unit  50  (shown in  FIG. 1 ) is provided for purposes of explanation. The variable-heating system controller  20  includes a microcontroller  22 , and a first input terminal  24  for receiving a heat activation signal from a wire  40  connected to a thermostat (e.g., a “W” terminal on the thermostat). The variable-heating system controller  20  may have a second terminal  26  for receiving a low stage heat activation signal where a two-stage thermostat is used and connected via wire  44 . 
     In response to a thermostat activation signal, the variable-heating system controller  20  signals a valve unit  100  to establish gas flow to a burner  58 . The variable-heating system controller  20  may be a two-stage controller that is configured to signal the valve unit  100  to establish a low-stage gas flow rate for a predetermined time period, and to thereafter signal the valve unit  100  to establish a high-stage gas flow rate after expiration of the predetermined time period. This may be achieved by a first switching means  30  for switching a voltage source “V” to a relay device  32  that switches voltage to a first connection  132  on the valve unit  100  to establish a low stage gas flow rate, and a second switching means  36  for switching voltage to a relay device  38  that switches voltage to a second connection  134  on the valve unit  100  to establish a high stage full-capacity gas flow rate to the burner  58 . Alternatively, the variable-heating system controller  20  may be configured to provide (via wire  34 ) a pulse-width-modulation or other equivalent signal to the valve unit  100 , which indicates a desired operating capacity level. Accordingly, an exemplary variable-heating system controller  20  may be configured to respond to one or more thermostat activation signals by signaling a valve unit  100  to establish a high capacity gas flow rate, a low capacity gas flow rate, or one or more variable gas flow rates therebetween. 
     Referring to  FIG. 2 , one exemplary embodiment is shown of a valve unit  100  for adjusting gas flow rates within a heating unit or combustion apparatus. The valve unit  100  includes a movable valve member  122  for adjusting a gas flow rate. In response to a magnetic field generated by a coil  120 , the valve member  122  moves relative to a valve seat  102  to vary a gas flow rate to a valve outlet  105 . To vary the gas flow rate, the valve member  122  is configured to move a controlled amount based on a magnetic field that is established by an input voltage applied to a coil  120 . 
     Specifically, the exemplary valve unit  100  in  FIG. 2  includes a first valve seat  102 , a second valve seat  103  substantially co-aligned with the first valve seat  102 , and an outlet  105 . The valve unit  100  includes a first valve element  112  that is spaced from the first valve seat  102  when the first valve element  112  is in an open position, and seated against the first valve seat  102  when the first valve element  112  is in a closed position. The valve unit  100  includes a second valve element  114  substantially co-aligned with the first valve element  112  and moveable relative to the second valve seat  103 , where the second valve element  114  is spaced from the second valve seat  103  when the second valve element  114  is in an open position, and seated against the second valve seat  103  when the second valve element  114  is in a closed position. The valve unit  100  further includes a valve member  122  that operatively moves the first valve element  112  and second valve element  114  in response to a magnetic field generated by a coil  120 . The valve member  122  is configured to move the first and second valve elements  112 ,  114  relative to at least the second valve seat  103  to vary an opening area therebetween. More preferably, the valve member  122  is configured to move a first distance to pull the first valve element  112  away from a closed position against the first valve seat  102  towards an open position, and to move beyond the first distance to pull the second valve element  114  away from a closed position against the second valve seat  103  and towards an open position. The valve member  122  is configured to move a controlled amount based on the magnetic field generated by the coil  120  to vary the opening area to provide a desired high-capacity gas flow rate through the valve unit  100 . 
     In the various valve unit embodiments of the present disclosure, the function of establishing a select high-capacity gas flow rate or low-capacity gas flow rate may be equivalent to establishing a corresponding select outlet pressure at the outlet  105  of the valve unit  100 , as explained below. Specifically, to achieve a desired high-capacity or low-capacity gas flow rate at a downstream location of a burner  58  (as shown in  FIG. 1 ), the various embodiments of a valve unit  100  are configured to adjust an opening area relative to a valve seat (e.g., seats  102 ,  103  in  FIG. 2 ) to establish an outlet pressure at an outlet  105  that yields the corresponding desired gas flow rate. Table 1 shown below illustrates various exemplary outlet pressure levels that are approximately equivalent to various exemplary gas flow rates, which rates are expressed as a percent of full capacity gas flow for the valve unit  100 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Pressure 
                 Capacity 
               
               
                   
                 (inches water column) 
                 (% full capacity flow for Natural Gas) 
               
               
                   
                   
               
             
            
               
                   
                 5.00 
                 100 percent  
               
               
                   
                 3.60 
                 85 percent 
               
               
                   
                 1.30 
                 50 percent 
               
               
                   
                 0.45 
                 30 percent 
               
               
                   
                 0.20 
                 20 percent 
               
               
                   
                   
               
            
           
         
       
     
     Accordingly, the various valve unit embodiments are configured to control an input to a coil  120  to move a valve member  122  to establish an outlet pressure at the outlet  105  that corresponds to a selected capacity level or gas flow rate. In the exemplary valve unit  100  in  FIG. 2 , the coil  120  is preferably a solenoid coil that is configured to move the valve member  122  relative to a valve seat (e.g., seats  102 ,  103 ) based on a magnitude of the generated magnetic field, which is dependent on an input voltage applied to the coil  120 . By controlling the input voltage that is applied to the coil  120  to move the valve member  122 , the valve unit  100  can vary the extent of opening area between the first and second valve seats  102 ,  103  and the first and second valve elements  112 ,  114 . Accordingly, the valve member  122  can vary the opening area between the first and second valve elements  112 ,  114  and the first and second valve seats  102 ,  103 , to vary the gas flow rate to the outlet  105 . 
     However, when the coil  120  and valve member  122  are operated to adjust the opening area to establish and maintain very low gas flow rates (e.g., at a low outlet pressure of about 1.0 inch of water column or less), the regulation over such low gas flow rates is typically not within a desired tolerance range. To establish such a consistent low capacity gas flow rate, the present exemplary valve unit  100  further includes a first opening port  140 , and a second opening port  142  (or bypass orifice). The first and second opening ports  140 ,  142  are disposed downstream of the valve seat (e.g., seats  102 ,  103 ). The valve unit  100  further includes a closure member  144  that is movable between an open position and a closed position relative to the first opening port  140 . When the closure member  144  moves to an open position, a high-capacity gas flow rate (set by valve member  122 ) is communicated to an outlet  105 . When the closure member  144  moves to a closed position against the first opening port  140 , a low-capacity gas flow rate is communicated via only the second opening port  142  to the valve outlet  105 . In the valve unit  100  shown in  FIG. 2 , the high-capacity gas flow rate is communicated via both the first and second opening ports  140 ,  142  to the outlet  105 , but may alternatively be communicated to two or more outlets, as shown in  FIG. 3 . 
     The second opening port  142  (or bypass orifice) preferably has an opening area less than about 0.100 inches 2  that is effective to provide a low gas flow rate at a low outlet pressure of about 1.0 inch of water column or less, and to maintain the desired gas flow rate within a tolerance of +/−0.15 inches of water column. More preferably, the second opening port  142  may have a flow adjustment member  150  that is adjustable for varying the opening area of the second opening port  142 . The flow adjustment member  150  may comprise a screw or other threaded component that is suitable for impinging or restricting the opening area of the second opening port  142 . 
     The valve unit  100  further includes a solenoid  148  for selectively moving the closure member  144  between the open position and closed position to selectively establish a high-capacity gas flow rate or low capacity gas flow rate, respectively, to the outlet  105 . Accordingly, the valve unit  100  includes a coil  120  for adjusting a valve member  122  to vary a high capacity gas flow rate through a valve seat (e.g., seats  102 ,  103 ), and a solenoid for selectively communicating either the high capacity gas flow rate or the low capacity gas flow rate to the outlet  105 . This function enables the valve unit  100  to provide a desired high capacity gas flow rate to a heating apparatus, as well as a consistent low capacity gas flow rate that is maintained within a desired tolerance range. 
     Referring to  FIG. 3 , an alternate construction of the valve unit  100  is shown. Much like the valve unit  100  in  FIG. 2 , the alternate construction in  FIG. 3  includes a valve member  122  that moves relative to a valve seat (e.g.,  102 ,  103 ) in response to a signal input to a coil  120  for varying a high-capacity gas flow rate, and first and second opening ports  140 ,  142 ′ and closure member  144 . However, in this alternate construction, the first opening port  140  leads to the outlet  105 , and the second opening port  142 ′ leads to a second outlet  107  for communicating a low capacity gas flow rate. The second outlet  107  may communicate low capacity gas flow rate to a pilot burner, for example, and may be adjustable using a flow adjustment member  150  to vary the opening area of the second opening port  142 ′. Accordingly, the closure member  144  is movable between an open position, in which a high-capacity gas flow rate is communicated via the first opening port  140  to an outlet  105 , and a closed position against the first opening port  140 , in which a low-capacity gas flow rate is communicated via only the second opening port  142 ′ to the outlet  107 . As with the valve unit  100  shown in  FIG. 2 , the alternate construction also enables the valve unit  100  to provide a desired high capacity gas flow rate to a heating apparatus, as well as a consistent low capacity gas flow rate that is within a desired tolerance range. 
     In the particular embodiments shown in  FIGS. 2-3 , the valve unit  100  includes a solenoid operator in which the coil  120  is configured to move the valve element  112  to vary gas flow rate through the valve unit  100  based on the magnetic field generated by the coil  120 . The valve member  122  is configured to directly vary an opening area relative to at least one valve seat (e.g., seats  102 ,  103 ) to vary the gas flow rate. Accordingly, the valve member  122  is direct-acting, in that it moves in response to an electrical signal to vary an opening area, without any mechanical linkage to a diaphragm for displacing the valve member  122 , as in conventional two-stage gas valve devices. The input voltage applied to the solenoid coil  120  is that which provides the desired low-stage gas flow rate and the high-stage full-capacity gas flow rate. However, other embodiments of a valve unit are contemplated in which input to a coil moves a valve member to vary a gas flow rate, as explained below. 
     Referring to  FIG. 4 , a second embodiment of a valve unit  100 ′ is shown in which the coil  120  is part of a stepper-motor that causes a valve member  122  to move based on a voltage applied to the stepper-motor coil  120 . The stepper motor operated valve unit  100 ′ includes a main diaphragm chamber  109 , and a main diaphragm  104  disposed therein that is coupled to the valve member  122 . The main diaphragm  104  controllably displaces the valve member  122  and associated valve element  112  relative to a valve seat  102  to vary an opening area  108  in response to changes in pressure in the main diaphragm chamber  109 , to thereby permit adjustment of fuel flow through the valve seat  102 . The stepper motor operated valve unit  100 ′ further includes a servo-regulator diaphragm  110 , which is configured to regulate fluid flow to the main diaphragm chamber  109 . The servo-regulator diaphragm  110  therefore controls the fluid pressure applied to the main diaphragm  104  to move the valve member  122 , to control the rate of flow through the valve seat  102 . The stepper motor operated valve unit  100 ′ also includes a stepper motor coil  120  configured to move in a stepwise manner to displace the servo-regulator diaphragm  110 , and causes the valve member  122  to move and regulate the rate of flow through the valve unit  100 ′. 
     The stepper motor coil  120  accordingly provides control over the extent of opening area relative to the valve seat  102 , to provide modulated gas flow operation. The stepper motor operated valve unit  100 ′ preferably includes a valve controller  130  that is configured to receive an input signal that is indicative of a desired operating capacity level or gas flow rate from the furnace system controller  20  (shown in  FIG. 2 ). As shown in  FIG. 4 , the stepper motor operated valve unit  100 ′ drives the stepper motor to move in a step-wise manner, which causes the stepper motor to displace the servo-regulator diaphragm  110  and move the valve member  122  relative to the valve seat  102 , to thereby control the rate of fuel flow through the valve seat  102 . The valve controller  130  determines the number of steps the stepper motor coil  120  must rotate to move the servo-regulator diaphragm  110  and valve member  122  to establish the requested gas flow rate. 
     To accommodate low capacity gas flow rates, the valve unit  100 ′ further includes a first opening port  140 , and a second opening port  142  that is smaller than the first opening port. The first opening port  140  and the second opening port  142  are disposed downstream of the valve seat  102 . The valve unit  100  further includes a closure member  144 . The closure member  144  is movable between an open position, in which a high-capacity gas flow rate is communicated via the first and second opening ports  140 ,  142  to an outlet  105 , and a closed position against the first opening port  140 , in which a low-capacity gas flow rate is communicated via only the second opening port  142  to the outlet  105 . The second opening port  142  preferably has an opening area less than about 0.100 inches 2  that is effective to provide a low gas flow rate at a low outlet pressure of about 1.0 inch of water column or less, and to maintain the desired gas flow rate within a tolerance of +/−0.15 inches of water column. More preferably, the second opening port  142  may have a flow adjustment member  150  that is adjustable for varying the opening area of the second opening port  142 . The valve unit  100 ′ further includes a closure solenoid  148  for selectively moving the closure member  144  between the open position and closed position to selectively establish a high-capacity gas flow rate or low capacity gas flow rate, respectively, to the outlet  105 . Accordingly, the valve unit  100 ′ includes a coil  120  for adjusting a valve member  122  to vary a high capacity gas flow rate through a valve seat  102 , and a solenoid for selectively communicating either the high capacity gas flow rate or the low capacity gas flow rate to the outlet  105 . This selectivity enables the valve unit  100 ′ to provide a desired high capacity gas flow rate to a heating apparatus, as well as a consistent low capacity gas flow rate that is maintained within a desired tolerance range. 
     In the above described embodiments, the valve unit  100  includes a valve member  122  that moves in response to a magnetic field generated by a coil  120  to vary a gas flow rate through the valve unit  100 , where the coil  120  may be a component of a solenoid or a stepper-motor that causes the displacement of a valve member  122 . The various embodiments of a valve unit  100  further include a valve controller  130  for controlling the input to the coil  120  to controllably vary the gas flow rate of the valve unit  100 , as explained below. 
     Operation at High-Capacity Gas Flow Rates 
     Referring back to  FIGS. 2-4 , the valve unit  100  includes a valve controller  130  that is configured to control input to the coil  120 . As stated, the valve unit  100  includes a first connection  132  and a second connection  134 . When the first connection  132  receives a high-stage activation signal from a two-stage controller (e.g., system controller  20  in  FIG. 1 ), the valve controller  130  is configured to control the input to coil  120  to move the valve member  122  to establish the high-capacity gas flow rate, and further configured to actuate the closure solenoid  148  to move the closure member  144  to an open position such that the high-capacity gas flow rate is communicated via the first and second opening ports  140 ,  142  to the outlet  105  of the valve unit  100 . 
     Similarly, where valve unit  100  receives a pulse-width-modulated signal or the like that includes information indicative of an operating capacity level corresponding to an outlet pressure above 1 inch of water column, the valve controller  130  is configured to control input to the coil  120  to establish a high-capacity gas flow rate corresponding to the operating capacity level, and configured to actuate closure solenoid  148  to move closure member  144  to an open position such that the high-capacity gas flow is communicated via the first and second opening ports  140 ,  142  to the outlet  105 . 
     Operation at Low-Capacity Gas Flow Rates 
     Where the valve unit  100  receives a pulse-width-modulated signal indicative of an operating capacity level corresponding to an outlet pressure below 1 inch of water column, the valve controller is configured to control input to the coil  120  and to deactivate closure solenoid  148  to move closure member  144  to a closed position against the first opening port  140 , such that a low-capacity gas flow rate is communicated via only the second opening port  142  (or bypass orifice) to outlet  105 . The opening area of the second opening port  142  is effective to establish a low-capacity gas flow rate that is maintained within a desired tolerance range. 
     Alternatively, when the valve unit  100  receives a low stage activation signal (e.g., a signal from a two-stage furnace controller received via connection  134 ), the valve controller  130  is configured to control input to the coil  120  and to deactivate closure solenoid  148  to move closure member  144  to a closed position against the first opening port  140 . In this position, a low-capacity gas flow rate is communicated via the second opening port  142  to the outlet  105  as long as the low stage activation signal is present at the second connection  134 . 
     Referring to  FIG. 5 , a schematic diagram of the valve controller  130  is provided. The valve controller  130  may comprise a microprocessor  138  that is in communication with the first connection  132  configured to receive a high-stage activation signal, and with the second connection  134  configured to receive a low-stage activation signal (from a heating system controller  20  that provides two-stage control). Alternatively, a pulse-width-modulation or other equivalent signal may be received, which signal indicates a desired operating capacity level. The microprocessor  138  may control a switching device  136  to controllably switch a voltage on an off to provide a pulse-width modulated voltage signal to a coil  120  (for either a solenoid or a stepper-motor), for controllably varying the gas flow rate of the valve. Alternatively, the microprocessor  138  may include pulse width modulation output that can directly control application of voltage to the coil  120 . 
     Accordingly, the above embodiments of a valve unit  100  including a valve controller  130  that is connectable to and operable with a furnace system controller  20  that may be two-stage controller or a variable capacity furnace controller. The valve unit  100  including a valve controller  130  is configured to control a closure solenoid  148  for selectively moving the closure member  144  between an open position, in which a high-capacity gas flow rate is communicated via the first and second opening ports  140 ,  142  to an outlet  105 , and a closed position against the first opening port  140 , in which a low-capacity gas flow rate is communicated via only the second opening port  142  to the outlet  105  to thereby provide a consistent low capacity gas flow rate that is within a desired tolerance range. These and other advantages provide novel advantageous improvements over conventional two-stage gas valves. 
     Thus, it will be understood by those skilled in the art that the above described embodiments and combinations thereof may be employed in various types of heating systems with any combination of the above disclosed features, without implementing the others. It will be understood that the stepper motor driven gas valve and controller described above may be utilized in other forms of heating and cooling equipment, including water heater and boiler appliances. Accordingly, it should be understood that the disclosed embodiments, and variations thereof, may be employed without departing from the scope of the invention.