WO1997037162A1

WO1997037162A1 - Direct-acting boost-enhanced pressure regulator

Info

Publication number: WO1997037162A1
Application number: PCT/US1997/005119
Authority: WO
Inventors: Christopher G. Turney; Paul W. Heald
Original assignee: S.H. Leggitt Company
Priority date: 1996-03-29
Filing date: 1997-03-28
Publication date: 1997-10-09
Also published as: AU726201C; EP0888510A4; AU2595497A; EP0888510A1; NZ331761A; CA2248562C; CN1215467A; CN1143069C; CA2248562A1; AU726201B2

Abstract

A boost-enhanced gas pressure regulator (53) consists of a bonnet (11) and a body (12; main casing) that are secured together so as to capture a diaphragm (13) between both components. An actuator (16) providing a pair of control channels (38) and a relief seat (32) in one component is connected to the diaphragm (13) to be moved with and by the latter. A boost/seat tube (20) has external guide surfaces (49) which serve to guide and control its movement, and it also has an internal gas flow passage (52) in which an elastomeric seat disk (21; valve member) is mounted. The boost/seat tube (20) is restricted to travel in a linear fashion (direct action) with respect to an inlet orifice/valve seat (44) by a plurality of guide surfaces (49) that are an integral part of the orifice insert (44), upon which certain contact areas (70, 72) of the boost/seat tube (20) are slidable.

Description

DIRECT-ACTING BOOST-ENHANCED PRESSURE REGULATOR BACKGROUND AND GENERAL SUMMARY OF THE INVENTION This invention is applicable to a wide range of gas pressure-regulating applications, but is designed for particularly advantageous use in propane outdoor cooking appliance applications. For example, the device may be used to supply an appliance with a consistent pressure in the range of 11 inches of water column when provided with inlet pressures up to 250 psig. Many conventional devices used in these applications experience three flow performance limitations that are inherent to their design. The first limitation is termed "droop," i.e. pressure droop, which is caused by the change in the effective area of the diaphragm as it moves and the loss of load experienced by the diaphragm control spring throughout the same motion. These factors combine to cause the delivery (output) pressure to decrease as flow increases. The described invention partially overcomes this limitation by using velocity boosting to compensate. Velocity boosting subjects the diaphragm to a lower pressure than the controlled downstream pressure, which allows for a larger valve opening and higher flow rates. The second limitation, hysteresis or backlash, is partially caused by change of direction of friction forces throughout the range of motion for the device. Hysteresis causes inconsistency in the performance of such a device. The described invention reduces the effect of this limitation by providing a novel floating suspension for valving and velocity-boost components together with smoothly rounded continuous guides and slide surfaces providing essentially point-to-point controlled, low-friction contact for mechanism control. This combined with novel and improved component configurations and actuation mechanisms provides a device having novel control and operational characteristics which produce significantly enhanced performance consistency. The third limitation is caused by physical obstructions in the flow path direction. The described invention has eliminated virtually all unnecessary obstructions from the flow stream. OBJECTS OF THE INVENTION

Broadly stated, the principal object of the invention is to provide a new and novel gas pressure regulator for use in propane outdoor cooking appliance applications and the like, different from the type customarily used heretofore in this field, having novel and advantageous structures and features which provide significantly improved results. A further object of the invention is to provide an enhanced-performance, single-stage regulator valve having novel and advantageous physical componentry which cooperatively provides substantially and uniquely improved results and enables use of very small inlet orifice diameter, small diaphragm diameter and small overall regulator size, providing for reduced costs as well as implementation advantages. A still further and more particular object of the invention is to provide an improved pressure regulator valve having novel internal componentry which provides velocity boosting features in a novel and enhanced manner. Another important object of the invention is to provide an enhanced- performance, low-cost regulator that lends itself effectively to the use of automated manufacturing equipment and provides for ease of assembly. Additional objects of the invention, as well as additional advantages thereof, will become apparent following consideration of the ensuing disclosure.

These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The following brief description of the figures, and the related figures themselves, exemplifies a particular preferred embodiment of the invention constituting the best mode presently contemplated. As will be understood, other embodiments of the invention as well as changes and variations in the particular structure shown in these figures are no doubt possible and may very well suggest themselves to those skilled in the art after studying this disclosure and these figures.

Fig. 1 is a perspective representation of an assembled pressure regulator in accordance with the invention that shows external features of a single-outlet version of the device;

Fig. 2 is a perspective representation of an assembled regulator in accordance with the invention that shows external features of a dual-outlet version of the device;

Fig. 3 is a trimetric cross-sectional view of a regulator in accordance with the invention which shows the shape, location and relationship of internal components of the device;

Fig. 4 is an enlarged cross-sectional side view of a regulator in accordance with the invention further illustrating internal components and their respective features;

Fig. 5 is a trimetric view of the diaphragm assembly used in the regulator shown in the preceding figures;

Fig. 6 is a trimetric view of the internal mechanism of the regulator, showing the boost/seat tube with its mounting and actuation means;

Fig. 7 is a right side view of the internal mechanism of the regulator shown in Fig. 6;

Fig. 8, including Figs. 8A and 8B, is a two-view perspective showing the valve- controlling actuator used in the preferred embodiment, which comprises part of the diaphragm assembly shown in Fig. 5;

Fig. 9A is a perspective view of the preferred boost/seat tube structure used in the regulator;

Fig. 9B is an end elevational view of the preferred boost/seat tube structure; Fig. 10A is a perspective view of the preferred orifice insert used in the regulator;

Fig. 10B is an end elevational view of the preferred orifice insert structure; Fig. 11 is an enlarged front cross-sectional view showing the gas inlet of the valve body with its inlet fitting and seal; and Fig. 12 is an enlarged side view of the preferred boost/seat tube, showing the force vectors acting thereon during operation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Referring to Fig. 4, a regulator valve 53 is comprised of a generally circular dish- shaped bonnet 11 and a corresponding body 12 that are secured together by mechanically deforming a ring of material 54 on body 12 to fold over a flange 55 on bonnet 11. A generally circular fabric-reinforced elastomeric diaphragm 13 that features a molded convolution 31 is sealingly captured between bonnet 11 and body 12 to form an upper chamber 57 and a lower chamber 56. This seal is formed by the squeeze of an integral seal bead 30 extending around the edge of diaphragm 13 between flange 55 and a seal groove 28 formed in the top of body 12. The amount of squeeze required to form a seal is controlled by an annular shoulder 29 forming a positive stop that provides a rest for flange 55. Diaphragm 13 is combined with a diaphragm plate 14, relief spring 17, spring retainer 15, and actuator 16 to complete diaphragm assembly 59 (See Fig. 5).

Actuator 16 has an upstanding central post 42 (Figs. 7 and 8) having a plurality of longitudinal ribs 41 that aid in centering diaphragm 13 and diaphragm plate 14 during assembly of these parts. Spring retainer 15 is a disc-like member having a central hole 36 (Fig. 4) that slips over post 42 of actuator 16 and includes an annular skirt or ledge 37 (Fig. 5) that compresses relief spring 17 against diaphragm plate 14. Diaphragm assembly 59 is preferably secured by an ultrasonic heat-stake operation that fixes the position of spring retainer 15 on post 42 of actuator 16. Actuator 16 has a lower extremity 16A which contacts and interacts with boost/seat tube 20, as described below, to form the control mechanism of the regulating valve. A control spring 18 (Fig.4) is compressed and centered between the top inside surface 60 of bonnet 11 and ring 34 of diaphragm plate 14.

Boost/seat tube 20 houses a seat disk 21 (Figs 4 and 9B) by means of a seat holder 50 that is suspended centrally by support ribs 51 within a smooth and otherwise- unrestricted tubular passage 52 (Fig. 9A) extending longitudinally through the boost/ seat tube. Boost/ seat tube 20 is restricted to linear motion toward or away from a valve seat

44 which is aligned with seat disk 21 and defined by an orifice insert member 19 (Figs. 4 and 10). Orifice insert 19 is held in body 12 by a pair of drive screws 23 and has an o- ring 22 which encircles its lower cylindrical extremity 45 and forms a seal between orifice insert 19 and body 12. Inlet 26 of body 12 is designed to accept an inlet fitting 65 (See Fig. 11) that connects regulator valve 53 to a source of gas such as a propane supply cylinder valve. A seal is formed between inlet fitting 65 and body 12 by o-ring 67 to prevent gas leakage to atmosphere. Inlet fitting 65 is retained in body 12 by mechanically deforming inlet boss 68 on body 12 so as to force material from boss 68 into groove 66. Referring to Fig. 4, pressurized gas from a source is applied to inlet 26, through which the gas may flow into passage 61 , through orifice 43 (when the valve mechamsm is open), around seat disk 21 and seat holder 50, through the tubular boost passage 52 and out passage 58 to the appliance. The initial compression of control spring 18 between bonnet 11 and diaphragm assembly 59 upon assembly forces the valve mechanism to be in the full open position before inlet gas pressure is applied to inlet 26. As illustrated, orifice 43 is elongated and preferably oriented at an angle with respect to inlet passage

61, thereby orienting the inlet gas flow directly at seat disk 21 and along the axis of boost tube passage 52. Also, as previously indicated, the diameter of orifice 43 may be considerably smaller than would otherwise be required to meet outlet flow requirements (on the order of only half that size), due to the velocity boost effect provided, helping to maintain acceptably low lockup (shutoff) inlet pressure differentials. Accordingly, the inlet gas flow substantially restricted and accelerated by the small inlet orifice, flares out around seat disk 21 and accelerates past this smoothly rounded restriction due to the "vena contracta" effect, flowing with increased velocity axially of and along boost passage 52 into outlet passage 58.

Referring to Figs. 6-10, the operating mechanism of the described invention is mainly composed of actuator 16, boost/ seat tube 20, and orifice insert 19. Actuator 16 features a pair of mutually spaced control channels 38 in its lower extremity 16A, and also has a flat vertical surface 40. The control channels 38 each provide a pair of oppositely disposed identically contoured surfaces 63, 64 which make sliding contact with one or the other of the opposite sides of a pair of control pins 48 extending outwardly from each side of boost/seat tube 20, to form a camming mechanism. Thus, as the diaphragm assembly 59 moves up and down in response to the gas pressure in chamber 57 and the spring forces acting on diaphragm 13, actuator 16 and its control channels 38 move with respect to boost/ seat tube 20 and its control pins 48, translating the boost/ seat tube longitudinally. The control channels 38 are preferably designed to provide a mechanical advantage of about 4: 1 to ensure a seal between seat disk 21 and valve seat 44 when there is no downstream demand, and to provide a lower mechanical advantage throughout the rest of the valve mechanism motion, to induce and enhance velocity boosting effects. The minimal, reduced-area points of contact between the contoured surfaces 63, 64 and control pins 48 aid in the reduction of hysteresis, but the overall manner in which the boost/seat tube 20 is supported, moved and guided provides a very significant reduction in friction for the overall mechanism, with corresponding improved regulator operation, as noted further below.

Boost/seat tube 20 is restricted to move in a linear fashion toward or away from valve seat 44 by the outermost end portions of control pins 48 and by a pair of guide pins 49 extending from opposite sides of the boost/seat tube 20 at a location along its length spaced from pins 48 (Figs. 6, 7, and 9), which ride along guide surfaces 47, 70 that are formed on the underside of generally cylindrical guides 72, 73 formed on the extended ends of upstanding arms 69, 71 of orifice insert 19 (Figs. 6, 7, and 10). The contact points between these pins and guides are the transverse intersection of cylindrical shapes, providing smoothly rounded point-to-point contact area that reduce friction in the motion of the boost/seat tube 20 and related valve mechanism. Orifice insert 19 also has two contact points 46 (Figs. 4 and 10B) that contact the flat vertical surface 40 of actuator 16 to provide consistent bi-directional linear motion with reduced friction.

It is to be noted that the structure and interrelationship of the slidable mechanism just described produces a unique low-friction support and guidance arrangement for the boost/ seat tube 20. More particularly, as indicated above and as shown in Fig. 7 (depicting the mechanism in actual operation), the boost/seat tube 20 becomes elevated during operation, with control pins 48 and guide pins 49 riding along the underside of guide surfaces 70 and 47 respectively rather than along the top of cylindrical member 72. This is caused by the shape and relative positioning of the component parts, including the contoured control channels 38, the pre-load effect of control spring 18, the inlet gas pressure and the chamber pressure, which combine to maintain a force couple on the boost seat tube 20 centering about its control pins 48 and acting to counterbalance the weight of the boost/seat mbe 20, elevating the latter to the generally cantilevered "floating" position just noted with respect to guide element 72 of orifice insert 19. This light sliding contact of pins 48 and 49 along guide surfaces 70 and 49 is the only contact between the boost seat tube 20 and orifice insert 19, i.e. , as illustrated in Fig. 7, the outward ends of pins 48, 49 and 49A do not contact the adjacent inside surfaces of orifice insert arms 69 and 71, and the rounded end extremity 19A of guide element 72 does not contact the adjacent side of boost/seat tube 20 or the mid-portion 49B between pins 49 and 49A.

The force vectors acting on boost/seat tube 20 which produce the force couple noted above are illustrated in Fig. 12, showing the boost/seat mbe from the side. The "Contact Force" vector shown there, acting downwardly on pins 48 and 49, represents engagement of these members with guide surfaces 70 and 47, respectively, and the

"Control Force" vector on pin 48 represents its engagement with the contoured control channel 38, in particular surface 63 thereof. The "Unbalance Force" essentially represents the inlet gas pressure acting on the face of the valve disk 21 and its annular mount 50. As a result of these factors, the larger-area bottom surfaces of the boost/seat tube 20 never contact or ride upon the adjacent surfaces of the orifice insert 19, and even pins 48 and 49A of the boost/seat tube normally remain above and out of contact with the top surface of cylindrical guide element 72 of orifice insert 19 (Fig. 7). Consequently, the amount of sliding friction which results during movement of the boost/seat tube toward and away from valve orifice 44 and the inlet end of outlet passage 58 is minimal, even though the boost/seat tube 20 is at all times being smoothly and positively guided.

As will be understood, during initial assembly of the operating mechanism, after the orifice insert 19 has been secured in place in body 12, the boost/seat mbe 20 is loosely slid into its position between arms 69 and 71 of the orifice insert 19, with pins 48 disposed between guide projections 72 and 73 and pins 48 and 49A resting atop guide projection 72. The axially displaced disposition of pins 49A with respect to pins 49 tends to limit the extent of allowable boost/seat tube tilt under these conditions since they engage the elongated guide surface 72 at different points and can be used to hold the forward portion of the boost/seat tube 20 in a somewhat elevated position in which seat disk 21 remains somewhat aligned with seat/orifice 43. Actuator 16 is then inserted into place from above, along with the rest of diaphragm assembly 59, with cam slots 38 sliding over and receiving pins 48. When the diaphragm assembly has been placed into position atop body 12, the bonnet 11 is then positioned over the diaphragm assembly and secured in place. When the bonnet 11 is so placed and secured, the top surface 60 of bonnet 11 contacts the top of control spring 18 and applies the aforementioned preload to it, while at the same time forcing actuator 16 downwardly. Since the contoured control channels or cam slots 38 are engaged over the guide pins 48, this downward movement of actuator 16 and the force of spring 18 moves the control channels 38 downward relative to the control pins 48, causing corresponding movement of the boost/ seat tube 20 toward the right as seen in Figure 4, opening the valve by moving seal 21 away from seat 44.

Referring to Figs. 4, 7, and 12 with the valve mechanism initially in its full open position as noted above, as gas is applied through inlet 61 and flows through orifice 43 it enters the adjacent end of boost/seat tube 20, flows over and around seat disk 21 into boost tube passage 52, and passes through the latter into outlet passage 58. Between passages 52 and 58, some of the gas also enters chamber 56, where its pressure is applied across the effective area of diaphragm 13. This offsets the force of control spring 18 and moves diaphragm assembly 59 upward, whereupon control channels 38 move upwardly while contacting control pins 48 to force boost/ seat mbe 20 and seat disk 21 toward valve seat 44, forming a restriction that controls flow to match downstream demand. In addition, the force of the inlet gas pressure acting on valve seat disk 21 creates the "Unbalance Force" noted above in connection with Fig. 12. As shown there, this force vector is generally aligned along the axis of boost/seat tube 20, and below the control pins 48. The effect of this is to elevate the entire boost/ seat tube 20 by rotating it to the position shown in Fig. 7, wherein pins 48 and 49A are moved upward to a position above and spaced from guide projections 72. In this position, the top of pins 48 engage the underside surface 70 of guide member 73, and the top of pins 49 engage the underside 47 of guide members 72, thereby creating the low-friction smoothly guided operating conditions noted above.

It should be noted that in the event there is no downstream demand, gas pressure increases inside chamber 56 until seat disk 21 forms a seal on valve seat 44, causing a zero flow or lockup condition. In this regard, the described invention also includes a safety feature commonly referred to as pressure relief. If pressure increases in chamber

56 to a predetermined percentage above lockup pressure, it is applied across the effective area of diaphragm 13 to offset the force of both control spring 18 and relief spring 17, allowing diaphragm plate 14 and relief seal 32 of diaphragm 13 to move upward and off of relief seat 39 and allowing flow of gas through relief holes 33 and 35 of diaphragm 13 and diaphragm plate 14, respectively. This flow of gas can then escape to atmosphere from chamber 57 through vent hole 25 in bonnet 11, reducing the pressure to a value which allows the assembly to reseal and return to normal operation. Additionally, if the mechanism becomes dislodged by some means allowing diaphragm assembly 59 to travel upward without resistance caused by the lockup condition, post 42 of actuator 16 is designed to contact surface 60 of bonnet 11, stopping the vertical motion and allowing the relief mechamsm to operate as described above.

As described previously, the mechanism of this device operates to control flow to meet downstream demand. When demand increases, outlet pressure decreases and this results in downward movement of diaphragm 13 and its related parts, including actuator 16, causing seat disk 21 to move away from valve seat 44 and thereby allowing more flow through the device to supply the new demand. This continues until the demand is satisfied and an equilibrium state is reached. Conversely, the same events occur in reverse for conditions of decreasing demand. Changes in inlet pressure and/or demand will cause the device to compensate by opening or closing the valve mechamsm in response to the new conditions, to again reach an equilibrium state. Since seat disk 21 and its seat holder 50 are integrally attached to and part of the boost/seat mbe 20, it will be understood that the entire boost/seat tube moves with corresponding movements of seat disk 21 toward and away from seat 44. During times of increasing flow through the device, when seat disk 21 moves away from seat 44, the end of the boost/ seat mbe 20 located nearest the entrance to outlet passage 58 moves increasingly closer thereto, thereby increasingly directing the increased flow of pressurized gas outward through passage 58. This has the effect of increasingly aspirating chamber 56 and reducing the pressure therein which acts on the underside of diaphragm 13. Conversely, movement of boost/ seat mbe 20 and seat disk 21 in the opposite direction, at times when the flow of gas is being reduced, moves the end of boost/seat tube 20 away from the entrance to outlet passage 58, causing an increased widening of the opening into chamber 56 and reducing the velocity-boost/pressure-aspiration effects and allowing increased pressure within the latter. Accordingly, the velocity boosting effect provided by the boost/seat mbe 20 is correspondingly varied, and enhanced. Tlirough the use of enhanced velocity boosting and reduced hysteresis, the described invention provides a pressure regulator having considerably improved operation.

Bonnet 11 (aluminum), body 12 (zinc), diaphragm plate 14 (plated steel), spring retainer 15 (plated steel), control spring 18 (stainless steel), relief spring 17 (stainless steel), and drive screw 23 (stainless steel) are preferably all rigid metal components. Diaphragm 13, seat disk 21, and o-ring 22 are flexible elastomeric components. Acmator 16, boost/seat tube 20, and orifice insert 19 are preferably constructed of rigid engineering thermoplastic resins such as Acetal, Polyethylene Terephthalate. Referring to Fig. 2, body 112 offers a second integral barbed outlet 124 with through-hole 158 to provide gas flow to appliances that have both a main burner and a smaller capacity side burner for propane outdoor cooking appliance applications.

The described invention provides consistent repeatable performance over a wide range of inlet pressures and flow rates while also enabling significant reduction in inlet orifice diameter (as much as one-half) and in diaphragm and overall regulator size; e.g. , on the order of as much as one-third, compared to conventional diaphragm-type regulators. The foregoing detailed description is considered that of a preferred embodiment only, and the particular shape and nature of at least some of the components (especially the orifice insert 19 and boost/seat tube 20) in this embodiment are at least partially based on manufacturing (e.g. , molding) advantages and considerations as well as on those pertaining to assembly and operation. Modifications of this embodiment may well occur to those skilled in the art and to those who make or use the invention after learning the nature of this preferred embodiment, and the invention lends itself advantageously to such modifications and alternative embodiments. Therefore, it is to be understood that the embodiment shown in the drawings and described above is provided principally for illustrative purposes and should not be used to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A direct-acting boost-enhanced gas pressure regulator, comprising in combination: a body having a regulator chamber with a gas inlet and outlet, said chamber communicating with gas flowing between said inlet and outlet to be pressurized thereby; a variable valve mechanism for controlling gas flow between said inlet and outlet in response to the amount of pressure inside said chamber; and a boost tube strucmre within said chamber, including a member having a generally tubular passage movably mounted between said inlet and outlet to form a variably continuous passage therebetween in coordination with the variable opening and closing of said valve mechanism, in a manner decreasing the pressure communicated to the inside of said chamber as said valve mechanism is increasingly opened.

2. A gas pressure regulator as set forth in Claim 1 , wherein said boost mbe member is coupled to said variable valve mechanism for coordinated movement therewith.

3. A gas pressure regulator as set forth in Claim 2, wherein said variable valve mechanism includes a movable valve member coupled to said boost tube member to move conjointly therewith.

4. A gas pressure regulator as set forth in Claim 3, wherein said valve member is operatively disposed within said generally tubular passage.

5. A gas pressure regulator as set forth in Claim 4, wherein said valve mechanism includes a seat and said valve member is movable toward and away from said seat to vary gas flow between said inlet and outlet, and wherein said generally mbular passage part of said boost tube member extends at least partially over and around said seat such that said member at least partially shrouds the seat and its surrounding area.

6. A gas pressure regulator as set forth in Claim 4, wherein said generally mbular passage surrounds said valve member and defines substantially free-flowing areas for gas passage therebetween within said boost mbe member.

7. A gas pressure regulator as set forth in Claim 6, wherein said valve mechanism includes a seat and said valve member is movable toward and away from said seat to vary gas flow between said inlet and outlet, and wherein said boost mbe member extends at least partially over and around said seat to at least partially shroud the seat and its surrounding area.

8. A gas pressure regulator as set forth in Claim 1, wherein said inlet, outlet and movably mounted boost tube member define an opening communicating into the interior of said chamber.

9. A gas pressure regulator as set forth in Claim 8, wherein said opening is variable in size in relation to movement of said boost tube member.

10. A gas pressure regulator as set forth in Claim 1, wherein said boost mbe strucmre includes a low-friction suspension mounting for said movably mounted boost tube member, comprising a plurality of spaced guide surfaces extending longimdinally along the outside of said boost tube member and slidable coupling elements extending therebetween such that said member slides longitudinally along said guide surfaces on said coupling elements as said member moves relative to said inlet and outlet.

11. A gas pressure regulator as set forth in Claim 10, including an inlet orifice structure mounted in said body and providing said spaced guide surfaces.

12. A gas pressure regulator as set forth in Claim 11 , wherein said inlet orifice structure also provides a valve seat for said valve mechamsm.

13. A gas pressure regulator as set forth in Claim 11 , wherein said valve mechamsm includes a valve member mounted for movement toward and away from said valve seat to vary the flow of gas through said inlet.

14. A gas pressure regulator as set forth in Claim 13, wherein said valve member is coupled to said boost tube member to move conjointly therewith.

15. A gas pressure regulator as set forth in Claim 14, wherein said valve seat is disposed near the end of a projection and at least a portion of said boost tube member with said generally tubular passage is telescopingly disposed over said projection to hood said valve seat.

16. A gas pressure regulator as set forth in Claim 15, wherein said telescopingly disposed portion of said boost mbe is slidable with respect to said valve seat.

17. A gas pressure regulator as set forth in Claim 10, including a pressure-sensing element located at least partially within said chamber and an acmator for moving said valve member in response to pressure variations sensed by said sensing element, said acmator being coupled to said boost mbe member to impart said movement thereto while also positioning said member for low-friction sliding movement along said guide surfaces.

18. A gas pressure regulator as set forth in Claim 17, wherein said actuator includes a pair of spaced cam surfaces and said boost tube structure includes a pair of spaced cam- follower members engaging said cam surfaces to move said boost mbe member in response to movement of said cam surfaces.

19. A gas pressure regulator as set forth in Claim 1, wherein a valve mechamsm includes a seat and said valve member is movable toward and away from said seat to vary gas flow between said inlet and outlet, and wherein said boost mbe member extends at least partially over and around said seat to at least partially shroud the seat and its surrounding area.

20. A gas pressure regulator as set forth in Claim 19, including an inlet orifice structure mounted in said body and providing said seat.

21. A gas pressure regulator as set forth in Claim 20, wherein said valve seat is disposed near the end of a projection and at least a portion of said boost tube member is telescopingly disposed over said projection to hood said valve seat.

22. A gas pressure regulator as set forth in Claim 21, wherein said telescopingly disposed portion of said boost mbe is slidable with respect to said valve seat.

23. A gas pressure regulator as set forth in Claim 10, including a pressure-sensing element located at least partially within said chamber and an acmator for moving said valve member in response to pressure variations sensed by said sensing element, said acmator being coupled to said mbular boost tube member to impart said movement thereto.

24. A gas pressure regulator as set forth in Claim 23, wherein said acmator includes a pair of spaced cam surfaces and said boost mbe strucmre includes a pair of spaced cam- follower members engaging said cam surfaces to move said boost tube member in response to movement of said cam surfaces.

25. A gas pressure regulator, comprising in combination: a body having an internal cavity with an inlet and outlet for pressurized gas; a regulator chamber communicating through a passage area with pressurized gas flowing from said inlet to said outlet, to sense the pressure of said gas; a variable valve mechamsm inside said cavity for controlling the amount of said gas flow in response to the sensed magnitude of said gas pressure; a movable closure member for effectively varying the size of said passage area to thereby vary the communication of gas pressure conditions to said regulator chamber; and at least one coupling operatively connected to said movable closure member and said variable valve mechanism for imparting conjoint movement therebetween, whereby the effective size of said passage area is varied in relation to the operation of said variable valve mechamsm.

26. A gas pressure regulator as recited in Claim 25, including a low-friction slide support for said movable closure member, comprising a plurality of mutually spaced guide surfaces supported in said body and a plurality of low-friction slide elements connected to said movable closure member and disposed in light sliding contact with said guide surfaces, said closure member moving by said slide elements sliding along said guide surfaces.

27. A gas pressure regulator as recited in Claim 26, wherein said movable closure member is loosely disposed between said guide surfaces, an. including an actuator for at least partially supporting said closure member in a

position while it is moved to effectively vary the size of said passage area, wherein said slide elements are disposed in light sliding contact with only some of said guide surfaces and is held free of other such guide surfaces to reduce friction effects during actual operation.

28. A gas pressure regulator as recited in Claim 27, wherein said closure member is elongated in shape and has a pair of spaced ends, and said actuator supports said closure member from a position nearer one end than the other, whereby said member is suspended in generally cantilevered fashion during actual operation.

29. A gas pressure regulator as recited in Claim 28, wherein said closure member is supported at least in part by a force couple applied thereto at said position nearer one end.

30. A gas pressure regulator as recited in Claim 29, wherein said valve mechamsm includes a valve member which is attached to said closure member for movement therewith by said acmator.

31. In a boost-enhanced gas pressure regulator, of the type having a regulator chamber with an inlet and an outlet, a variable valve mechanism for controlling gas flow between said inlet and outlet in response to the amount of pressure inside said chamber, and a boost strucmre movably mounted between said inlet and outlet to form a passage of variable closure degree therebetween in response to the operation of said valve mechanism and corresponding gas flow conditions between said inlet and outlet, the improvement wherein said boost structure comprises an elongated member having an internal passage for gas flow and external actuation strucmre by which said member may be moved longitudinally toward and away from said outlet, said external actuation strucmre comprising at least one engagement element having portions extending generally transversely of said elongated member, and an acmator member for engaging said at least one engagement element and moving it to thereby move said elongated member longimdinally toward or away from said outlet.

32. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim

31 , wherein said external actuation structure comprises at least one projection extending outwardly from said elongated member; and wherein said actuator member includes a cam surface for slidably engaging said at least one projection to move said elongated member by camming movement of said projection.

33. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim

32, wherein said cam surface is contoured to apply differing degrees of mechanical advantage to said projection at different positions of movement of said elongated member.

34. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim 32, wherein said cam surface and said projection are configured to apply an angular moment to said projection during camming movement thereof under conditions of actual operation and thereby apply a transverse positioning force to said elongated member during its longitudinal movement caused by said camming.

35. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim

34, wherein said cam surface comprises a slot disposed between a pair of oppositely- disposed and mutually spaced cam faces.

36. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim

35, wherein said projection comprises a pin-like member having a cross section which fits into said slots.

37. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim

34, further including at least one slide element on the outside of said elongated member disposed for sliding contact with an elongated guide surface extending along the outside of said elongated member, said transverse positioning force acting to hold said at least one slide element in at least light sliding contact with said guide surface.

38. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim 34, wherein said transverse positioning force acts to move said elongated member at least partially out of contact with adjacent structure within said chamber during said longitudinal movement of said member.

39. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim 38, further including at least one slide element on the outside of said elongated member disposed for sliding contact with an elongated guide surface extending along the outside of said elongated member, said transverse positioning force acting to hold said slide element in at least light sliding contact with said guide surface.

40. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim 39, wherein said cam surface comprises at least one slot having a pair of oppositely- disposed and mutually spaced cam faces.

41. The improvement for a boost-enhanced gas pressure regulator as set forth in Claim 31 , wherein said internal passage has a smooth, regular and continuous peripheral wall which is substantially devoid of gas flow restrictions, and including a valve element disposed within said passage and spaced from said peripheral wall by open areas providing for minimal gas flow restriction.