CA1237359A - Air valve - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A gas or air flow regulator for installation in a gas conduit has a housing having a gas inlet, a gas outlet and a gas passageway extending between the inlet and the outlet. The passageway has a section at one end that converges radially inwardly in the direction of gas flow.
A piston member is arranged along the centre axis of the passageway and is capable of axial movement along the passageway. A cylinder is mounted on the piston member and is capable of sliding axially relative to the piston member. The cylinder is substantially closed and contains a gas. A plunger is rigidly mounted on the cylinder and surrounds the same. The plunger which is arranged centrally in the passageway and in the region of the converging section, is movable in the direction of fluid flow in response to an increased rate of gas flow. A coil spring biases the plunger in an axial direction opposite the direction of fluid flow. A motor mechanism is connected to the piston member and is adapted to move the latter together with the cylinder means and the plunger axially as required to increase or decrease the size of an annular opening between the plunger and the inside surface of the converging section and thereby regulate the rate of fluid flow. The piston member and the cylinder means together act as a damper.

Description

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This invention relates to an air or gas valve capable of maintaining constant volume gas flow in a conduit.
It is well known to control the flow of air to a particular area in a building in order to supply heated or cooled air by the use of a thermostat. Thus there may be many thermostats in a large building for adjusting the temperature of the air in various sections of the building.
Because the demand for warm or cool air can vary considerably throughout a building, substantial variations of the air pressure in the supply conduits can occur in the absence of mechanisms to control such fluctuations. A
change in the supply of air over a short period of time to a given area may be disturbing to persons working or living in the building. The variation can cause changes in -the draft in a room and may result in a change in noise level.
The gas flow regulator described herein can satisfactorily maintain the volume of gas or alr flow constant in a particular area even if the pressure in the main supply mains changes. In addition the regula-tor is adjustable so that ~he volume of air flow to an area or region in the building can be controlled locally.
According to the present invention, a gas flow regulator for installation in a gas or air conduit includes a housing having a gas inlet, a gas outlet and a gas passageway extending between the inlet and outlet. The passageway has a section that converges radially inwardly .r ~373~

in the direction of gas flow. A piston member is arranged along the centre axis of the passageway and is capable of axial movement along the passageway. A cylinder is mounted on the piston member and is capable of sliding axially relative to the piston member. ~ plunger is rigidly mounted on and surrounds the cylinder means which is substantially closed. The plunger which is arranged cen-trally in the passageway and in the region of the converging section, is movable in the direction of gas flow in response to an increased rate of gas flow. Spring means bias the plunger in an axial direction opposite to the direction of gas flow. A motor is connected to the piston member and is adapted to move the piston member, cylinder means and attached pllmger axially as required to increase or decrease the size of an annular opening between the plunger and the inside surface of the converging section and thereby regulate the rate of gas flow. The piston member and cylinder means together act as damper means for movements of the plunger member caused by changes in the rate of gas flow.
Preferably the spring means is a coil spring arranged in the cylinder means and has one end resting against a piston located at one end of the pis-ton member.
Further features and advantages will become apparent from the following detailed description, given by way of example, taken in conjunction with the accompanying drawings.

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In the drawings, Figure 1 is a top view of a gas flow regulator constructed in accordance with the invention;
Figure 2 is a cross~sectional elevation of the ~low regulator taken along the line II-II of Figure l;
Figure 3 is a cross-sectional elevation showing the support for one end of the piston member, which elevation is taXen along the line III-III o Figure 2;
Figure 4 is a perspective view oE the piston member and a coil spring used to bias a plunger mounted on the piston member;
Figure 5 is a perspective view of the plunger and a cap member used to close one end of the cylindrical - passageway extending through the plunger;
Figure 6 is a cross-sectional detail taken along the line VI-VI of Figure 2; and Figure 7 is a side detail view with parts separated showing the placement of a rubber sheet to close the opening in the top of the housing; and Figure 8 is a detail view showing the construction of -the rubber sheet and the slit formed therein.
A gas or air flow regulator 10 is adapted for installation in a gas or air conduit which may be part of an air conditioning or heating system. The adjoining sections of conduit are shown in part in dashed lines in Figure 1. The regulator has a housing 12 which can be fabricated in one piece, or alternatively, with Eirst and second pieces 14 and 16. If only a small quantity o:f the ~3~5~3 regulators are being produced, a one piece housing can be used, which housing is preferably made of aluminum and by a spinning process. If a greater quantity of regulators is being produced, it is economical to have a two piece housing wherein the first piece 14 is of uniform width and made of galvanized metal and the second piece 16 forms a converging section and is made from aluminum. The first piece 1~ can be made of standard galvanized duct work or other standard duct material having a round cross-section thus avoiding the use of expensive aluminum for -this portion. The second piece 16 can be made from spun and/or stamped aluminum. The two pieces c,an be connected together by means of overlapping ends which fit tightly together and/or by the use of sheet metal self tapping screws (not shown).
As can be seen readily from Figure 2, the housing 12 is open-ended with the gas or air inlet 18 being located at one end of the housing and the gas or air outlet 20 being located at the other end which is of smaller diameter. A gas or air passageway 22 extends between the inlet and the outlet and this passageway has a section 24 that converges radially inwardly in the direction of gas flow, which direction is indicated by the arrow A in Figure

2.
A piston member 26, shown separately in Figure ~
is arranged along the centre axis of -the passageway and i5 capable of axial movement along the passageway. The member 26 comprises an elongate rod or shaft 28 and a piston 30 rigidly mounted on one end of the rod. The piston 30 can "

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be made from fiber reinforce~ plastic using an injection molding process. After molding the piston is centerless-ground to achieve close tolerance and perfect roundness, It could also be made of aluminium and have a Teflon*
coated edge so that close tolerance to a dash pod 40 is maintained within a wide temperature range. The rod is mounted on two legs 32 that extend diametrically across the passageway 22. Each leg 32 is formed with bent ends 34 to permit attachment of each end to the housing by means of a suitable bolt and nut or self-tapping screw. Each leg is made of metal plate and is installed with its wide side parallel to the air flow in order to minimize air resistance and in order to have maximum structural rigidity against horizontal forces created by the rod 28 which is supported by the legs. Each leg has a cylindrical centre section 36 having a circular opening therein for reception of a bushing 38 of the self-aligning type. The bushings 3~
permit slight radial movements by the rod 28 and this helps to compensate for minor assembly misalignments.
Mounted on the piston member 26 is a cylinder means or dash pod 40 which is capable of sliding axially relative to the piston member~ The preferred dash pod 40 is made from stock aluminium tubing with its inside diameter machined or otherwise constructed to achieve close tolerance to the piston 30. The cylinder means is substantially closed with its ends being covered by metal or plastic caps or covers 42 and 44. The cap 42 is formed with a rim 46 extending about its periphery and this rim fits snugly over a projecting portion 48 of the cylinder - means, which portion is shown clearly in Figure 5. The ~,~
- *trade mark ~l~3~ 9 other cap 44 has a circular opening 50 therein ~or passage o:E the rod 28. The caps 42 and 44 can be made by an injection molding process using Eiber reinforced plastics or from machined or hydroformed aluminium to maintain equal thermal expansion characteristics for high temperature fluctuation applications. They could also be made from sheet metal using a stamping process if desired. The two caps can be connected to the cylinder means or the adjoining plunger 52 by a press fit. Located in the cylinder means is a coil spring 54 which biases the aforementioned plunger in an axial direction opposite to the direction of gas flow. One end of the spring res-ts against the piston 30 while the other end rests against the end cap 44. The spring 54 is preferably non-linear so that it can properly compensate for fluctuations in the gas o pressure in the system. Preferably the position of the piston 30 on the end of the rod 28 is adjustable so that the spring 54 can he precompressed the required amount for proper operation of the regulator. The characteristics and quality of the spring 54 can vary from one spring to another and the ability to adjust the position of -the piston compensates ~or these variations. For example the hole through the piston 30 can be threaded along with the ena of the rod 28. By further threading the piston onto the end o~ the rod, the spring 5~ can be compressed to a greater extent. When the position of the piston has been propery adjusted, the piston can be held in that position by tighteniny a set screw indicated at 56 in Figure 4.
There is a close fit between the cylindrical surface of the ~3~73~9 piston 30 and the inner wall of the cylinder means. It will be appreciated that movement of the cylinder means to the right in Figure 2 with no corresponding movemen-t of the piston member will cause compression of the spring and the air or gas in the chamber 58. At the same time the space between -the end 60 of the piston and the end cap 42 will expand creating a partial vacuum condition. Compressed air in the chamber 58 can only escape slowly through a -tlny clearance or opening between the rod 28 and the surrounding end cap 44 or through -the small clearance between the piston 30 and the rod 28 into the chamber 62. Similarly when the cylinder means moves to the left in Figure 2, air can be drawn only slowly into the chamber 58 which is now expanding in size. Thus rapid movement of the cylinder means on the piston member is prevented and the cylinder means and piston member toge-ther act as a damper for movements of the p]unger which will now be described in further detail.

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The plunger 52 is preferably constructed from spun aluminum and made of two parts 64 and 66 wh:ich can be held together by sheet metal screws (not shown). The part 64 has a semi-spherical shape while the part 66 is in the form of a truncated cone with the cone tapering in -the direction of gas flow. In the illustrated embodiment of Figure 2, the truncated cone part is located within the converging section of the housing. Where the part 66 connects to the second part 64 there is a lip 6~ which orms an acute angle with the centre axis of the housing.
Located at approximately the same distance from the centre axis of the housing is a sloping shoulder connecting the converging section oE the housing with a flow straightening section 72 which allows the air flow to straighten out after passing through the converging section and over the shoulder 70. This in turn enhances the air flow and minimizes noise caused b~ such flow. The shoulder 70 forms an acute angle with the centre axis of the housing and this minimizes turbulence caused by the shoulder while at the same time it provides a tight seal with the lip 68 when the plunger has travelled the maximum distance to the right.
Motor means are connected to the piston member 26 and are adapted to move the piston member, cylinder means and attached plunger 52 axially as required to increase or decrease the size of the annular opening formecl between the plunger and the inside surface of the converging sec;tion of the housing. Thus by means of the motor means, the rate of gas flow can be regulated. The main components of the motor means are a motor 76 capable of providing linear motion, a lever 78 connected at one end to the piston member 26 and extending through the top side of the housing, and a link member 80 connecting the output of -the motor to the top end of the lever. The motor 76 can be pneumatic, electric or electronic and its linear mo-tion should be of sufficient stroke and power to overcome system static pressure and air velocity pressure. The motor is preferably mounted on the housing 12 by means of a horizontally extending bracket 82 which preferably has a number or slots or holes formed therein for mounting the motor. In this way the L-shaped frame 84 to which the motor is connected can be accurately positioned on the bracket 82 to provide for -the proper stroke. Bolts and nuts 86 can be used to detachably connec-t the frame 84 to the bracket 82. The bracket 82 is preferably connected to the housing by two upstanding legs 88, one of which is shown in Figure 2. The height of these legs is adjustable to permit the height of the motor above the housing to be adjusted. One way of constructing the legs 88 is shown in Figure 6. A generally U-shaped member 90 having two upstanding sides 92 is connected to the top of the housing 12. The bottom section of the member 90 is curved to match the curvature of the housing. A series of bolt holes 94 are provided in the sides 92 (see Figure 2). Two plate members 96 extend downwardly from the motor bracket 82 and ~3~)3r~3 are fixedly connected to opposite sides thereof. These plates 88 have sets of bolt holes corresponding to -the holes 94. With the motor arranged at the proper height, bolts 98 can be inserted through the holes to connect the plates 88 to the sides of the member 90.
The rnotor 76 has a .shaft 100 on which is mounted a ring 102 the position of which can be set by a set screw 104. The ring 102 allows for a fine adjustment of -the motor's minimum position. The link member 80 can he in the form of the S-ring shown. One end of the S-ring passes through a hole in the shaft 100 while the other end passes through one of a series of holes or slots 106 formed along the upper end of the lever 78. It is thus possible to vary the leverage ratio of the lever 78 by adjus-ting the height of the motor 76 and the point of connection of the S-ring to the lever 78. Thus it is possible to vary the range of movement of the rod 28 despite a constant length of motor stroke. It will be seen that the rate or volume of air flow is adjustable and, whatever adjustment is made, the full stroke of the motor can still be used.
With further reference to the lever 78, at a central location along the lever, it is connected to a pivot pin 110. The pin 110 extends across a gap formed in a plate 112 which is bolted to the top of the housing. The bottom end of the lever 78 is formed with an elonga-te slot 114 through which extends a pin member 116. A suitable bushing connects the pin ll~ to the rod 28. The bushing ~;~373~

transmits only the horizontal component oE the lever motion in order to prevent undue s-tress on the rod and lts supporting bushings.
In order to seal or close the opening in the housing through which the lever 78 extends, there ls provided a thin rubber or other synthetic elastic sheet 120 shown in Figures 7 and 8. This sheet has a slit 122 formed in its centre through which -the lever ex-tends. The sheet is sandwiched between the top of the housing and the member 10 90.
Arranged near the upper end of the lever on the outside of the housing is a dial 118 with a scale thereon that, in the illustrated embodiment, is numbered from 0 to 6. The location of the lever relative to the dial 118 provides an indication of the rate of gas flow. If desired a calibration sheet or tag can be affixed to the outside of the housing, which sheet or tag will show approximately the volume of air flow for a cer-tain dial reading.
It will be appreciated by those skilled in the art that when the plunger 52 is in its leftmost position as seen in Figure 2, the cross-sectional free area 120 will be at its maximum, permitting a maximum air flow for a given air pressure at the inlet. When the plunger is in its rightmost position, the lip 68 will be in contact with the shoulder 70 and the cross-sectional free area for air flow will be zero, resulting in a zero air Elow. It will be further appreciated that as inlet static pressure increases, the air velocity through the housing increases in a non-linear relationship. An increase in the air ~3~13~;~

velocity exert.s additional pressure on the spherical face o-f the plunger and this in turn will cause the plunger to move in the direction of the air flow relative to the rod or shaft 28. This in turn decreases ~he cross-sectional free area 120 which lessens the rate of air flow. By a suitable selection of curvature for the converging section 24, face area for the semi-spherical part 64, and spring 54 for a given position of the rod 28, lever 78 and motor 76, the plunger will move axially wi-th the rod 28 as desired to compensate for air pressure fluctuation and maintain the desired constant air flow.
It will be further appreciated that when the plunger is in its rightmost position and air flow is stopped, the velocity pressure acting on the spherical face of the plunger disappears and this permits t.he spring 54 to push the plunger back to an open position, at which position air flow is resumed. With a resumption of air flow, the plunger may once again go to its righ-tmost po~sition. This oscillating action of -the plunger can result in a chattering noise unless a mechanism is provided to dampen the movement of the plunger. The aforementioned cylinder means and piston provide the required dampening means.
Figure 2 of the drawings is a scale drawing done to a one-half scale of a preferred embodiment. The illustrated embodiment is designed for connection to an 8 inch diameter pipe at the inlet end 18. In this embodiment the area covered by the semi-spherical part 64 is approximately 23.75 square inches leaving a cross-sectional ~L~3~3~9 free area, for the position shown of 26.5 square inches approximately. The truncated cone part 66 has a length in the axial direction of approximately 3 inches. The outlet end 20 has a diameter in this embodiment of approximat.ely 5-1/4 inches. The axial length of the converging section 24 is approximately 5 inches.
It will be appreciated by those skilled in the art that various modifications and changes can be made to the described gas flow regulator without departing from the spirit and scope of this invention. ~ccordingly all such changes and modifications as fall within the scope of the appended claims are intended to be covered and included in the invention.

Claims (10)

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

1. A gas flow regulator for installation in a gas or air conduit comprising:
a housing having a gas inlet, a gas outlet and a gas passageway extending between said inlet and said outlet, said passageway having a section that converges radially inwardly in the direction of gas flow;
a piston member arranged along the centre axis of said passageway and capable of axial movement along said passageway;
cylinder means mounted on said piston member and capable of sliding axially relative to said piston member, said cylinder means being substantially closed;
a plunger rigidly mounted on and surrounding said cylinder means, said plunger being arranged centrally in said passageway and in the region of said converging section and movable in the direction of gas flow in response to an increased rate of gas flow;
spring means for biasing said plunger in an axial direction opposite to the direction of gas flow;
and motor means connected to said piston member and adapted to move said piston member, cylinder means, and attached plunger axially as required to increase or decrease the size of an annular opening between said plunger and the inside surface of said converging section and thereby regulate the rate of gas flow;

wherein said piston member and cylinder means together act as damper means for movements of said plunger caused by changes in the rate of gas flow.

2. A gas flow regulator according to claim 1 wherein said spring means is a coil spring arranged in said cylinder means and having one end resting against a piston located at one end of said piston member.

3. A gas flow regulator according to claim 1 wherein said plunger is in the form of a truncated cone at one end thereof, said cone tapering in the direction of gas flow.

4. A gas flow regulator according to claim 1, 2 or 3 wherein said motor means includes a lever connected at one end to said piston member and extending through a side of the housing and a motor capable of providing linear motion and connected by a link member to the other end of said lever.

5. A gas flow regulator according to claim 1, 2 or 3 wherein said piston member includes a slidable rod extending along the centre axis of said passageway and a piston mounted on one end of said rod and wherein said rod is mounted in bushings of the self-aligning type.

6. A gas flow regulator according to claim 1, 2 or 3 wherein said cylinder means has an opening at one end through which a rod forming part of said piston member extends and a small opening is provided between said rod and said one end of said cylinder means to permit the slow escape of gas from said cylinder means.

7. A gas flow regulator according to claim 2 wherein said spring is a non-linear coil spring and the other end of said spring rests against an end wall of said cylinder means.

8. A gas flow regulator according to claim 1, 2 or 3 wherein said motor means includes a lever connected to a pivot pin mounted on said housing and further connected at one end to said piston member and a motor connected by a link member to the other end of said lever and wherein a dial with a scale thereon is arranged next to said lever on the outside of said housing, the location of the lever relative to said dial providing an indication of the rate of gas flow.

9. A gas flow regulator according to claim 1, 2 or 3 wherein said housing is open-ended with said gas inlet being located at one end of said housing and said gas outlet being located at the other end which is of smaller diameter.

10. A gas flow regulator according to claim 1, 2 or 3 wherein said housing is constructed from first and second pieces connected end-to-end, said first piece being of uniform width and made of galvanized metal and the second piece forming said converging section and made from aluminum.