Slow opening gas valve

An improved slow opening gas valve providing for continuous gradual and smooth opening of the gas valve includes an expansible auxiliary chamber connected to an expansible control chamber by a metering orifice. The expansible auxiliary chamber slows expansion of the expansible control chamber, thereby slowing opening of the gas valve and allowing gas to ignite at a lower pressure with a much less audible sound. The gas valve is provided with a normally closed valve member for controlling flow of gas through the gas valve and a diaphragm forms a movable wall of the expansible control chamber that is operable upon expansion of the chamber to move the valve member to an open position. The expansible auxiliary chamber also comprises a movable diaphragm to control the opening of the gas valve and provide gas flow gradually and smoothly. In an alternate embodiment, a gas valve is configured to provide an initial gas flow through a bypass orifice in the closed valve member, which enables ignition of the gas at an optimum gas pressure instantly, followed by a gradual and smooth opening of the valve member. This arrangement provides a "step" function followed by the desired slow opening of the valve member.

BACKGROUND OF THE INVENTION
 1) Field of the Invention
 The present invention is directed to the field of gas controls, and in
 particular to an improved slow opening gas valve having an expansible
 auxiliary chamber connected to an expansible control chamber by a metering
 orifice to slow the expansion of the expansible control chamber and
 thereby slow the opening of the gas valve.
 2) Description of the Related Art
 It is well known that gas valves of the type to which the present invention
 relates are configured to provide gas at an outlet for ignition at a
 specific pressure level. In many of these gas valves, the amount of gas
 provided at the outlet at the time ignition takes place causes an
 undesirable audible ignition. This audible ignition results from the rapid
 opening of the gas valve which causes excessive gas build-up in the
 combustion chamber of for example, a furnace, before ignition. Thus, many
 of these "fast" open gas valves introduce too much gas before ignition
 takes place, thereby causing a very rough and/or audible ignition. In
 addition to producing this undesirable audible ignition, these gas valves
 may create large flames upon ignition which could be dangerous.
 A variety of gas valves are known in the art for providing slow opening
 valves and ignition at lower gas pressures. In general, however, many of
 the known-gas valves do not provide a sufficient duration of continuous
 valve opening and further do not provide a smooth and gradual opening of
 the gas valve. Additionally, these gas valves are generally complex in
 both design and operation, thereby increasing the likelihood of problems
 during operation.
 Some of these known valves attempt to restrict the flow of gas to the
 operating or control gas side of a regulator diaphragm, while others add
 tortuous paths to the operating side of a regulator diaphragm. Still other
 valves add second diaphragms to regulate operating pressure or utilize
 solenoids in connection with pumps to slow the opening of the valves.
 Finally, other known gas valves include pressure relief valves or
 regulated by-pass valves for controlling gas pressure.
 Generally, the known gas valves which include a second diaphragm, do not
 use that second diaphragm to slow the opening of the valve, but utilize
 the diaphragm to control operating pressure or venting of the valves.
 Overall, these gas valves are relatively complex, which may result in
 problems with reliability. Further, these gas valves fail to provide both
 a slow and continuous smooth opening of the valve. Thus, an undesirable
 audible or rough ignition may still occur.
 What was needed was a gas valve with a simple design, that could be
 produced inexpensively, and that not only provided gas flow for lower
 pressure ignition, but also provided gas at a continuously and smoothly
 increasing rate to avoid undesirable rough or audible ignitions.
 SUMMARY OF THE INVENTION
 In order to overcome these shortcomings and other needs in the art, the
 slow opening gas valve of the present invention introduces considerably
 less gas at the time of ignition by providing continuous gas flow both
 slowly and smoothly increasing, therefore allowing gas to ignite at a
 lower pressure with a much less audible sound.
 According to one aspect of the present invention, a slow opening gas valve
 is constructed to allow gas to ignite at a low pressure, thus providing a
 much lower audible and less rough ignition, along with less rollout of gas
 flame upon ignition. The slow open gas valve of the present invention is
 of the type having an inlet, an outlet and an expansible control chamber.
 The gas valve is provided with a normally closed valve member for
 controlling flow of gas through the gas valve. A diaphragm forms a movable
 wall of the expansible control chamber and is operable upon expansion of
 the chamber to move the valve member to an open position. The improvement
 to the gas valve is an expansible auxiliary chamber connected to the
 expansible control chamber by a metering orifice, which slows the
 expansion of the expansible control chamber and thereby slows the opening
 of the valve member in the gas valve. The expansible auxiliary chamber
 comprises a moveable diaphragm and a control device, such as a regulator
 preferably comprising a biasing spring, for controlling movement of the
 diaphragm.
 The volumes of the expansible control chamber and expansible auxiliary
 chamber are preferably configured to coordinate to slow the opening of the
 valve member and provide continuous gas flow at the outlet smoothly. The
 volumes of the expansible chambers are configured to provide control of
 the opening of the valve member, such that gas at the outlet is provided
 gradually. Additionally, the diameter of the metering orifice is
 configured to control gas flow from the expansible control chamber to the
 expansible auxiliary chamber, thereby slowing the opening of the valve
 member and providing gas at the outlet gradually and smoothly.
 According to another aspect of the present invention, a slow opening gas
 valve with a normally closed valve member is provided with a bypass
 orifice which is configured to initially allow a required flow with the
 valve member closed, followed by a gradual and smooth opening provided by
 the expansible chambers and the metering orifice. This initial flow
 through the bypass orifice provides a "step" function followed by the
 desired slow opening of the valve member. This function provides optimum
 outlet pressure for gas ignition instantly and thereafter opens the valve
 member smoothly, resulting in the desired continuous gradual and slow
 opening.
 According to still another aspect of the present invention, a slow opening
 gas valve is provided such that after a specified time period, determined
 by the volumes of the expansible control chamber and the expansible
 auxiliary chamber, and the size of the metering orifice, the valve member
 is sufficiently open to allow ignition of gas and then continues to
 gradually open to provide full gas flow through the valve. Therefore, the
 gas valve provides a desirable continuous slow and gradual opening feature
 which produces less gas at the time of ignition, thereby minimizing
 ignition noise and rollout of gas flame that normally results from typical
 "fast" opening gas valves.
 According to yet another aspect of the present invention, a method of
 controlling flow of gas uses a metering orifice to control the flow of gas
 through a valve having a valve member and an expansible control chamber,
 and comprises the step of slowing the expansion of the expansible control
 chamber using an expansible auxiliary chamber connected to the expansible
 control chamber by the metering orifice, thereby slowing the opening of
 the gas valve. The metering orifice and the expansible auxiliary chamber
 are sized to provide opening of the valve member gradually and smoothly.
 The method may further comprise the step of slowing the opening of the gas
 valve using a regulator coordinating with the expansible auxiliary chamber
 and the step of initially allowing gas flow with the valve member closed
 by using a bypass orifice, followed by a gradual and smooth opening. The
 initial flow through the bypass orifice provides optimum ignition gas
 pressure instantly, followed by a continuous and smooth opening of the
 valve member.
 Thus, the present invention provides numerous novel features and advantages
 over prior gas control valves. In particular, the invention provides
 continuous slow gas valve opening that is both smooth and gradual, thereby
 resulting in ignition of gas at a low pressure achieving a much quieter
 ignition than provided by other known gas valves. The quieter ignition of
 the gas valve of the present invention eliminates the undesirable sound
 that oftentimes can be heard throughout a house, such as when a thermostat
 turns on an attached furnace system. Additionally, by providing a smoother
 ignition, the gas valve of the present invention may prolong the life of
 the component parts of the furnace or other system to which it is
 connected. Finally, the gas valve of the present invention, by allowing
 ignition at a lower gas level, not only reduces possible dangers resulting
 from excessive gas build-up before ignition, but is more efficient,
 thereby reducing the cost of use, as a result of the reduced amount of gas
 needed for ignition.
 While the principal advantages and features of the present invention have
 been explained above, these and other features and advantages will be in
 part apparent and in part pointed out below.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
 A typical prior art "fast" open gas valve is shown generally in FIGS. 1 and
 2 and designated by reference character A. The prior art gas valve is not
 configured to provide a slow opening of valve member B and thereby
 typically causes an audible and/or rough ignition. In particular, the
 prior art gas valve does not provide an expansible auxiliary chamber
 connected to an expansible control chamber of the gas valve by a metering
 orifice.
 A slow opening gas valve providing for both continuously gradual and smooth
 opening of its valve member is designated generally by reference numeral
 20 in FIGS. 3, 4, 5 and 6.
 As shown in FIG. 4, the improved slow opening gas valve of the present
 invention, indicated generally as 20 in FIG. 4, is basically comprised of
 a valve housing 22, an inlet 24, an outlet 26, an outlet valve seat 28, an
 outlet valve member 30, and an expansible control chamber 32 connected to
 an expansible auxiliary chamber 34 by a metering orifice 36. The outlet
 valve seat 28, outlet valve member 30 and expansible control chamber 32
 are disposed within the valve housing 22 for control of the flow of gas.
 The valve housing 22 is preferably molded in two pieces with an upper
 portion 25, as more clearly shown in FIG. 7, and a lower portion 27. The
 upper portion 25 and lower portion 27 are connected by bolts or similar
 fastening members. The inlet 24 is formed on the left-hand side of the
 valve 20 as shown in FIG. 4. The inlet 24 is threaded to facilitate
 connection to a gas source and an inlet filter 38 is provided for
 filtering impurities from gas provided at the inlet from a gas source. The
 outlet 26 is formed on the right-hand side of the valve 20 as shown in
 FIG. 4. The outlet 26 is likewise threaded, thereby facilitating
 connection to a gas burning apparatus, such as a furnace. The outlet 26 is
 provided with an outlet filter 39 for filtering impurities that might
 otherwise enter outlet 26 from the outside environment, such as during
 connection to a gas burning apparatus. Also, both the left-hand and
 right-hand side of valve 20 are tapped and provided with threads 23 to
 enable flange mounting of valve 20.
 The gas valve 20 generally provides selective communication of gas from the
 inlet 24 to an inlet chamber 40, through an outlet chamber 42 and out of
 the outlet 26. The inlet chamber 40 comprises an inlet valve member 44
 disposed adjacent to the inlet 24 that controls the flow of gas from the
 inlet. The inlet valve member 44 is provided on the distal end of a valve
 stem 46, which valve stem 46 is constructed as part of an armature 48 of
 an inlet solenoid 50. The inlet valve member 44 and inlet solenoid 50 are
 provided for controlling flow of gas from the inlet 24 to the outlet
 chamber 42. An inlet valve seat 52 is further provided such that upon
 energization of the inlet solenoid 50, the inlet valve 44, which is
 normally engaged in its closed position on the inlet valve seat 52, is
 lifted off the inlet valve seat 52 by armature 48, thereby permitting gas
 supplied to the inlet 24 by a gas source, to flow from the inlet 24 to the
 inlet chamber 40 and to the outlet chamber 42.
 Outlet valve member 30 is normally disposed on outlet valve seat 28, both
 of which are contained within outlet chamber 42. Outlet valve member 30 is
 disposed on the distal end of a valve stem 54, which is provided as part
 of an armature 56 of an outlet solenoid 58 for controlling the flow of gas
 from the outlet chamber 42 to the outlet 26. In response to energization
 of the outlet solenoid 58, the outlet. valve 30, which is normally engaged
 in its closed position on the outlet valve seat 28, is lifted off the
 outlet valve seat 28 by the armature 56, thereby permitting flow of gas
 through the outlet chamber 42 to the expansible control chamber 32 via a
 control gas orifice 62.
 Inlet solenoid 50 and outlet solenoid 58 each comprise a direct acting
 automatic valve with a seal tube 94, a core 92 and field replaceable coils
 96, which are all provided within a solenoid housing 98. Further, the
 solenoids 50 and 58 are provided with connections 100 on an upper surface
 102 of the solenoids for providing power to the solenoids and connecting
 the solenoids to a control unit or control circuit operable to energize
 and de-energize the solenoids when desired or needed.
 Within the outlet chamber 42 is provided a main regulator poppet 60 with
 the control gas orifice 62 therethrough. The main regulator poppet 60 is
 operatively connected to the expansible control chamber 32, such that gas
 flow from the inlet 24 through the inlet chamber 40, and to the outlet
 chamber 42, flows into the main regulator poppet 60 and passes through the
 control gas orifice 62 into the expansible control chamber 32. Therefore,
 upon energization of the outlet solenoid 58, outlet valve 30 lifts off of
 outlet valve seat 28, thereby providing flow of gas through the outlet
 chamber 42, into the main regulator poppet 60 and through the control gas
 orifice 62 to the expansible control chamber 32. Additionally, with the
 outlet valve member 30 lifted off of the outlet valve seat 28, gas flow is
 also provided through a bypass orifice 68 to the outlet 26. The bypass
 orifice 68 is provided as part of the main regulator poppet 60 at its
 distal end 70, and communicates with the outlet 26.
 The expansible control chamber 32 comprises a diaphragm 64 forming a
 moveable wall of the expansible control chamber. The diaphragm 64
 comprises a peripheral edge 66 sealingly clamped between the upper portion
 25 and the lower portion 27 of the valve housing 22 to provide a fluid
 (i.e., gas) tight chamber. The expansible control chamber 32 provides
 control of the opening of the main regulator poppet 60, and therefore
 controls flow of gas both past the main regulator poppet 60 to the outlet
 26 and through the main regulator poppet 60 to the expansible control
 chamber 32, after energization of the outlet solenoid 58 lifts valve
 member 30 off of outlet valve seat 28. With the expansible control chamber
 32 communicating with the main regulator poppet 60 through the control gas
 orifice 62, control of gas flow from outlet chamber 42, out of outlet 26,
 is provided by downward pressure exerted on the diaphragm 64 by gas
 contained within the expansible control chamber 32 against the opposing
 force of a spring 65.
 The expansible control chamber 32 is operatively connected to and
 communicates with the expansible auxiliary chamber 34 via the metering
 orifice 36, which metering orifice 36 is preferably provided on a top
 surface 78 of the upper portion 25 of the valve housing 22. As is more
 clearly shown in FIG. 7, the expansible auxiliary chamber 34 comprises a
 moveable diaphragm 72 and a regulator 74 to provide for controlling the
 speed of the opening of the main regulator poppet 60 by controlling the
 rate of expansion of the expansible control chamber and thus the downward
 movement of the diaphragm 64. The changed rate of movement of the main
 regulator poppet 60 results from a changed rate of gas pressure build-up
 in the expansible control chamber 32 due to some gas flow into the
 expansible auxiliary chamber 34 via the metering orifice 36. The diaphragm
 72 comprises a peripheral edge 76 clamped between the top surface 78 of
 the upper portion 25 of the valve housing 22 and a protective cap 80,
 having an air vent 83.
 The regulator 74 preferably comprises at least one biasing spring 82
 between the cap 80 and diaphragm 72 that constantly urges the diaphragm 72
 of the auxiliary chamber 34 downward to resist expansion of the auxiliary
 chamber and provide control of the opening of the main regulator poppet 60
 and thus of the opening of the gas valve 20. The spring 82 is configured
 to provide sufficient force to the diaphragm 72, such that a rate of
 expansion of the expansible auxiliary chamber 34 is thereby defined. Thus,
 the expansible auxiliary chamber 34, which is operatively connected by the
 metering orifice 36 to the expansible control chamber 32, provides the
 desired controlled opening of the gas valve 20 and results in the
 provision of ignition of gas at a lower pressure level.
 The gas valve 20 is further preferably provided with an inlet pressure test
 nipple 84 and an outlet pressure test nipple 86 to allow for testing and
 determining the pressure levels at the inlet 24 and outlet 26,
 respectively. Thereafter, the desired gas pressure at the inlet 24 and
 outlet 26 can be set according to the specifications of the gas valve and
 depending upon the system to which the gas valve is attached. A pressure
 adjustment member 88 is provided with a regulator adjust screw 90 for
 setting the desired gas pressure within the gas valve 20. Thereafter, the
 pressure test nipples 84, 86 may again be used to determine if proper gas
 pressure has been achieved.
 In operation, inlet solenoid 50 and outlet solenoid 58 are initially
 energized, as shown in FIG. 8, in response to a command, e.g. from a
 control unit connected to the connections 100. The control unit may be a
 thermostat for controlling a furnace, but can be any control system
 configured or adapted for attachment to the connections 100. Upon
 energization of the solenoids 50 and 58, inlet solenoid 50 lifts inlet
 valve member 44 off of inlet valve seat 52 and outlet solenoid 58 lifts
 outlet valve member 30 off of outlet valve seat 28. Initially, gas flow is
 provided from the inlet 24, through the inlet chamber 40, to the outlet
 chamber 42 and through the bypass orifice 68 of the main regulator poppet
 60 to the outlet 26, as shown in FIG. 8. Gas flow is also provided through
 the control gas orifice 62 of the main regulator poppet 60 to the
 expansible control chamber 32. A small amount of gas also flows through a
 bypass bleed 108 which is preferably provided as a small slot 110 in a
 regulator diaphragm 111. One side of diaphragm 111 is exposed to
 atmospheric pressure through an air vent 113. Bypass bleed 108 further
 preferably comprises a venting passage 106 and an outlet port 112
 communicating the expansible control chamber 32 with the outlet 26.
 Gas flow through the control gas orifice 62 in the main regulator poppet 60
 begins to fill the expansible control chamber 32, with some of the gas
 passing through the metering orifice 36 into the expansible auxiliary
 chamber 34, and a small amount of the gas venting through bypass bleed
 108. The gas flow into the expansible auxiliary chamber 34 slows the rate
 of expansion of the expansible control chamber 32, and thus slows the
 downward movement of the diaphragm 64 of expansible control chamber 32.
 Gas pressure build-up in the expansible control chamber 32 is slowed by
 the flow of gas into the expansible auxiliary chamber 34 via the metering
 orifice 36. The slowing of the downward movement of the diaphragm 64 slows
 the downward movement of the main regulator poppet 60, thus slowing its
 opening, thereby resulting in slowing of the rate of increase of gas flow
 through the outlet chamber 42 and slowing gas pressure build-up at the
 outlet 26.
 After a selected time period, which is in part determined by the volume of
 the expansible control chamber 32, the volume of the expansible auxiliary
 chamber 34, the force applied by biasing spring 82, and the size of the
 metering orifice 36, the main regulator poppet 60 is moved downward
 sufficiently to allow full gas flow past valve seat 28 and to the outlet
 26 as shown in FIG. 9. As a result of the presence of auxiliary chamber 34
 and the metering orifice 36, movement of the main regulator poppet 60 is
 continuous and slow, so that gas flow provided to the outlet 26 gradually
 increases until full gas flow is achieved, as shown in FIG. 11. The prior
 art "fast" open gas valves provide full gas flow rapidly, as shown in FIG.
 12, thereby resulting in rough and/or audible ignitions.
 When solenoids 50 and 58 are de-energized in response to a deactivation
 command by a control unit connected to the connections 100 of the
 solenoids, such as when a thermostat determines that a furnace should be
 shut off due to a certain predetermined condition, inlet solenoid 50 moves
 inlet valve 44 onto inlet valve seat 52, thereby engaging the valve seat
 and blocking gas flow through the inlet 24 and into the gas valve 20.
 Further, and as more clearly shown in FIG. 10, outlet valve 30 does not
 immediately engage outlet valve seat 28 because residual gas in the
 expansible control chamber 32 remains, thereby preventing immediate upward
 movement of the main regulator poppet 60. It will take a few seconds for
 the expansible control chamber 32 to vent sufficiently and reduce gas
 pressure, thereby allowing for upward movement of the diaphragm 64 and
 upward movement of the main regulator poppet 60 sufficiently to allow
 engagement of outlet valve 30 onto outlet valve seat 28. Residual gas is
 vented back through the control gas orifice 62 and the bypass orifice 68
 to the outlet 26.
 Venting of gas is also provided through a second path comprising the
 previously-described bypass bleed 108.
 To provide gas ignition at a low pressure and enable a much quieter and
 smoother ignition than provided by "fast" opening valves, the diameter of
 the metering orifice 36 is preferably about 0.010 inches, but is
 preferably no less than about 0.008 inches and no greater than about 0.012
 inches. The diameter of the control gas orifice 62 is preferably between
 0.006 inches and 0.008 inches. Finally, the size of the bypass orifice 68
 is preferably about 0.0170 inches.sup.2. In general, maintaining a size
 ratio of 1.53/1.06 between the metering orifice 36 and control gas orifice
 62 results in the desired continuous gradual and slow smooth opening of
 the gas valve 20. However, these orifice dimensions, along with the
 volumes of the expansible control chamber 32 and expansible auxiliary
 chamber 34, and the stiffness of the springs 65 and 82, may be configured
 by one skilled in the art to provide the desired slow opening of the gas
 valve 20.
 In an alternative embodiment, the size of the bypass orifice 68 is
 configured to provide an initial required flow with the main regulator
 poppet 60 closed, followed by a slow opening of the poppet 60 previously
 described. This arrangement provides an optimum ignition gas pressure
 instantly, followed by a continuous and smooth opening of the main
 regulator poppet 60, whereby the gas flow gradually increases. As it can
 be appreciated by one skilled in the art, in this embodiment, the size of
 the bypass orifice 68 is preferably made larger. It should also be
 understood that more than one bypass orifice could be used. The size
 depends on the desired duration and extent of the initial gas flow. Thus,
 in this embodiment, a "step" function, as shown in FIG. 13, is provided to
 the otherwise slow opening of the valve 20.
 The slow open gas valve 20 of the present invention has been disclosed with
 reference generally to an application having a furnace system controlled
 by a thermostat. However, it should be apparent to one skilled in the art
 that the gas valve 20 of the present invention may be used in many
 different systems in which the control of gas flow is required, and in
 particular, where both continuous and smooth gradual opening of the gas
 valve is desired.
 Further, it should be understood that the expansible auxiliary chamber 34
 of the present invention, which is connected via the metering orifice 36
 to the expansible control chamber 32 of the gas valve 20, may be
 configured and employed in various different gas valves and is not limited
 to the gas valve shown. Further, the present invention may be used in
 connection with gas valves having different applications, such as
 providing for ignition of gas furnaces, gas cooking ranges or water
 heaters. In addition, although the gas valve 20 is shown with specific
 component parts and controls, the particular component parts are not
 required for the proper operation of the gas valve with the expansible
 auxiliary chamber 34. The expansible auxiliary chamber 34 of the present
 invention may be employed in gas valves having different chamber
 configurations and valve mechanisms.
 Therefore, while the present invention has been described by reference to
 specific embodiments, it should be understood and apparent to those
 skilled in the art that modifications and variations of the invention may
 be constructed without departing from the scope of the invention. It is
 therefore intended that the invention be limited only by the scope of the
 claims appended hereto, and their equivalents.