WO1990005869A1

WO1990005869A1 - Timing control valve in air exchange unit

Info

Publication number: WO1990005869A1
Application number: PCT/US1988/004058
Authority: WO
Inventors: Erling Berner
Original assignee: Trio Development Corporation
Priority date: 1988-11-14
Filing date: 1988-11-14
Publication date: 1990-05-31

Abstract

Apparatus for controlling the cycle timing of a two-position flapper valve (48) within an air exchange apparatus. The apparatus includes two cam plates (12), (14) which may be adjustably coupled to present a timing control component (15) having a combined cam surface which includes portions of the cam surfaces of both camp plates (12), (14). A motor (24) rotates the timing control component, the cam surface of which is engaged by a cam follower (56) mounted on an arm (52) coupled to the flapper valve (48). The rotation of the combined cam surface causes the movement of the cam follower and the arm, thereby moving the flapper valve between its two positions.

Description

TIMING CONTROL VALVE IN AIR EXCHANGE UNIT

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a timing control for a valve movable between two positions in an air exchange unit and, in particular, to an adjustable timing control for such a valve in which the valve may be maintained in one of its positions for variable periods of time.

Description of the Invention Background Apparatus for exchanging air within a room or other enclosure with fresh outside air are known. The benefits from such air exchanges are also well known. However, pollutants such as carbon monoxide, carbon dioxide or radon gas pose unique ventilation problems. Radon is a colorless, odorless gas produced by the breakdown of uranium and radium naturally found in soils throughout the nation. The gas typically seeps into the basements of homes, schools, and other buildings where it can collect. The more energy efficient and airtight the building, the greater the chances that the radon gas will not be able to escape and will continue to accumulate.

As the radon gas decays, it gives off radioactive alpha particles which can be inhaled and lodged in the lungs where they continue to radiate. The National

Academy of Sciences has reported that radon gas appears to be responsible for about 13,000 lung cancer deaths each year. The EPA has warned that radon is the number one environmental health risk in the country today. Radon, in addition to posing serious health problems, is a geographically widespread problem. Based on a survey of ten states, the EPA estimates that roughly ten percent of the country's 75 million homes have radon levels in excess of the government^rs maximum level of four picocuries per liter. Fortunately, ventilation systems have proven effective in reducing radon levels. One type of ventilation system is the subject of U.S. Patent No. 4,589,476, the disclosure of which is incorporated herein by reference. That apparatus exchanges air within an enclosure with outside air while the air within the enclosure is continually filtered. The apparatus includes a housing having four flow channels extending therefrom. Three of the flow channels are in communication with the enclosure while the fourth is in communication with the outside.

An exhaust fan is mounted in the first channel to produce an air flow from the enclosure. An air supply fan is mounted in the second channel to produce an air flow into the enclosure. A filter is located in- the third channel and a heat storing matrix is located in the fourth channel, which is the channel in communica- tion with the outside.

A flapper valve is disposed in the housing and can be positioned with respect to the four flow channels to establish a first operating mode in which the first channel is in air flow communication with the fourth channel thereby exhausting air from the enclosure while the third channel is in air flow communication with the second channel thereby providing a flow path for filtering the air in the enclosure. A second operating mode can be established in which the first channel is in air flow communication with the third channel thereby establishing a flow path for filtering the air in the enclosure while the fourth channel is in air flow communication with the second channel thereby drawing air into the enclosure. In the above-described apparatus, the valve cycles between its two positions, which positions establish the mode of operation, at regular intervals, e.g. two seconds. Thus, the valve is maintained in its outside air intake and exhaust positions for approximately similar periods of time. As such, the air exchanging apparatus exhausts approximately the same amount of air to the outside as is taken in from the outside. Therefore, the air within the enclosure remains at the same relative pressure as the outside air.

However, in certain instances it may be desirable to have the- air within the enclosure .remain at a higher or lower relative pressure than the outside air. For example, it may be preferable to maintain a higher relative pressure inside the enclosure to prevent pollutants such as carbon monoxide, carbon dioxide or radon gas from entering the enclosure. Where pollutants are trapped within, for example, the walls of an enclosure, it may be desirable to maintain a lower relative pressure inside the enclosure to draw the pollutants out. Thus, it is desirable to control the cycle time of the valve to achieve the desired pressure condition.

The subject invention is directed toward a means for providing an adjustable timing control for such a valve means which overcomes, among others, the above- discussed problem and which provides a simple, readily adjustable valve cycle timing control.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided an adjustable cycle time control means for the valve of an air exchange device. The main timing component of the present invention comprises a pair of identically shaped cam plates. The first cam plate includes an upper arcuate cam surface and a lower cam surface, while the second cam plate also includes upper and lower cam surfaces. The hub of the first cam plate is coupled to a unidirectional drive motor to rotate the first cam plate. The first cam plate also includes an arcuate slot having a radius of curvature centered on the axis of rotation of the first cam plate. A bolt passing through an aperture on the second cam plate provides, with a lock washer and a nut, a means for locking the second cam plate to the first cam plate in an infinite number of positions within the slot.

The timing component is coupled to and controls the rotation of a connecting rod which is the pivot point of a two-position flapper valve mounted within a plenum having four duct ports. A control arm is secured to one end of the connecting rod. A cam follower mounted on the control arm is spring biased into constant contact with the cam surface presented by the timing component. In operation, the bolt of the second cam plate is adjusted to a predetermined position relative to the slot in the first cam plate and tightened, thereby coupling the first and second cam plates to provide a combined cam surface of the timing component. If the second cam plate is coupled to the first cam plate in a position such that the second cam plate extends beyond the first cam plate, upon the rotation of the timing component by the motor, the cam follower first engages the cam rise portion of the cam surface of the second cam plate. This action results in the counterclockwise rotation of the control arm and the corresponding rota¬ tion of the flapper valve into its second position. As the cam follower continues to traverse the combined cam surfaces o_f the first and second cam plates, a dwell period is provided to maintain the flapper valve in its second position. When the cam follower reaches the top of the cam fall surface of the first cam plated the control arm commences clockwise rotation and thus moves the flapper valve clockwise to its first position.

Other objects and advantages of the present inven- tion will become apparent from the following detailed description taken with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of the top of the control assembly of the present invention;

FIG. 2 is an end elevational view of FIG. 1 with parts broken away;

FIG. 3 is a side elevational view taken along the line III-III; FIG. 4 is an exploded assembly view of the motor and cam plates of the present invention;

FIGS. 5a, 5b, and 5c are a series of views of the cam plate assembly of the .present invention in different operating orientations; FIG. 6 is a diagrammatic view of the control assembly of the present invention arranged with respect to a first position of a flapper valve within an air exchange unit; and

FIG. 7 is a diagrammatic view similar to FIG. 6 showing the control assembly of the present invention arranged with respect to the second position of a flapper valve within an air exchange unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The purpose of the control assembly of the present invention is to control the dwell time of a two-position flapper valve within an air exchange unit of the type described in U. S. Patent No. 4,589,476. The timing device of that patent provides only for fixed dwell times for the two-position flapper valve whereas the present invention will permit adjustable dwelling times of such a flapper valve.

The main timing component of the present invention comprises a pair of identically shaped cam plates 12 and 14, which, when mated, are sometimes referred to herein¬ after as—t-iming component 15. The cam plates need not be identical, however, in order to implement the principles of the present invention. Cam plate 12 may be considered the drive cam plate and includes upper arcuate cam surface 12a and a lower cam surface 12b, which are connected by a cam rise surface 12c and a cam fall surface 12d. Likewise, cam plate 14 has an upper arcuate cam surface 14a and a lower cam surface 14b, which are connected by a cam rise surface 14c and a cam fall surface 14d. Drive cam plate 12 includes a central hub 16 having an axial bore 18 extending therethrough; cam plate 14 has a central bore 20 adapted for alignment with bore 18 of cam plate 12. Bore 18 within hub 16 and bore 20 of cam plate 14 are adapted to receive the drive shaft 22 of constant speed, unidirectional drive motor 24. A set screw 26 on the periphery of hub 16 provides a means for locking cam plate 12 to shaft 22. Cam plate 12 includes an arcuate slot 28 having a radius of curva- ture cejitered on bore 18. Cam plate 14 includes an offset bore 30 on the same radius of curvature as slot 28. By means of bolt 32 passing through bore 30 of cam plate 14 and thence through slot 28 of cam plate 12, there is provided with lock washer 34 and nut 36 a means of locking cam plate 14 to drive cam plate 12 in an infinite number of positions within slot 28.

Timing component 15 is shown in FIGS. 5a, 5b and 5c in three orientations which provide varying dwell times for a flapper valve of an air exchange unit as described hereinbelow. In FIG. 5a, cam surfaces 12a and 14a as well as cam surfaces 12b and 14b are shown in precise registration with one another. In this configuration, bolt 32 is shown in the extreme left hand end of slot 28. In the configuration shown in FIG. 5a, timing component 15 provides a shorter period of dwell time when a cam follower is riding on cam surface 12a and 14a compared with the dwell time when a cam follower is riding on cam surfaces 12b and 14b. The other extreme variation in dwell times is shown in FIG. 5c wherein bolt 32 is shown in the extreme right hand end of slot 28. In this configuration, the dwell time when a cam follower is riding on cam surfaces 12a and 14a is long compared with the dwell time when the cam follower is riding on cam surfaces 12b and 14b. FIG. 5b is illustrative of equal dwell times wherein bolt 32 is shown in the midpoint of slot 28. In this configura¬ tion, the dwell time of a cam follower riding on cam surfaces 12a and 14a is roughly equal to when the cam follower is riding on cam surfaces 12b and 14b. Referring now to FIGS. 1-3, timing component 15 will be shown with a timing assembly 10 as it may be preferably mounted within an air exchange unit. Frame member 40 provides the basic mounting structure for timing component 15. Frame 40 is mounted to the housing 42 of an air exchange unit generally designed by the reference numeral 44. Timing component 15 is intended to control rotation of connecting rod 46 which is the pivot point of a two-position flapper valve 48 (see FIGS. 6 and 7). Connecting rod 46 is clamped within the bifurcated end 50 of control arm 52 by means of bolt 54. A cam follower 56 is mounted within slot 58 of the opposite end of control arm 52. Cam follower 56 is intended to maintain rolling contact with the cam surfaces presented by timing component 15. A tension spring 60 is mounted at one end to control arm 52 by means of cotter pin 62. Spring 60 is attached at its distal end 64 to frame member 40. The function of spring 60 is to bias cam follower 56 in constant contact with the cam surface presented by timing component 15. The operation of timing assembly 10 in an air exchange unit 44 will now be described by reference to FIGS. 6 and 7. As alluded to earlier, a two-position flapper valve 48 is shown mounted within a plenum 66 having four duct ports 68, 70, 72 and 74. With flapper valve 48 in its first position as shown in FIG. 6, incoming air through port 68 passes into plenum 66 and out through port 70; correspondingly, air passing through duct port 74 and into plenum 66 passes out through port 72. This air flow pattern represents one of two possible patterns for air exchange unit 44.

With timing component 15 being driven by motor 24 in a clockwise direction as indicated by the arrow 76, cam follower 56 first traverses the cam rise portion 14c of cam plate 14. This action results in the counter- clockwise rotation of control arm 52 about connecting rod 46 and the corresponding counterclockwise rotation of flapper valve 48 to its second position as shown in FIG. 7. In its new position within plenum 66, air flow passing into plenum 66 through duct port 68 is now diverted to exit through duct port 74. A reversing air flow through duct port 70 enters plenum 66 and is diverted to exit through duct port 72. If cam follower 56 continues to traverse the combined cam surfaces 12a and 14a of timing component 15, a dwell period is provided for flapper valve 48 in the position shown in FIG. 7. When cam follower 56 reaches the top of cam fall surface 12d of cam plate 12 and begins its descent along cam fall surface 12d, control arm 52 commences clockwise rotation about connecting rod 46 and thus moves flapper valve 48 clockwise to its original position shown in FIG. 6. Cam follower 56 continues its traverse of combined surfaces of 12b and 14b of timing component 15 until it reaches the base of cam rise portion 14c. Timing component 15 thus has completed one complete revolution and one cycle of flapper valve 48. If it is desired to alter the relative times in which the flapper valve 48 is maintained in its respective positions to control the relative periods of outside air intake and exhaust from air exchange unit 44, the bolt 32 is loosened and cam plate 14 is rotated relative to. cam plate 12 until the appropriate cam surface is presented by timing component 15 and the bolt 32 is retightened.

Assuming duct ports 68, 72 and 74 are in communica- tion with the enclosure and duct port 70 is in communi¬ cation with the outside, because of the configuration of timing component 15, the time spent exhausting air from the enclosure (FIG. 6) is approximately equal to the time spent drawing air into the enclosure (FIG. 7). If, however, the timing component is adjusted to have a profile as shown in FIG. 5a, then the time spent exhausting air from the enclosure is greater than the time spent drawing air into the enclosure such that an underpressure condition exists in the enclosure. If the timing—component is adjusted to have a profile as shown in FIG. 5c, then the time spent exhausting air from the enclosure is less than the time spent drawing air into the enclosure such that an over pressure condition exists in the enclosure. It will be understood that various changes in the details, materials and arrangements of parts which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

Claims

What is claimed is:

1. Apparatus for moving a flapper valve of an air exchange unit between first and second positions, comprising; an arm adapted at one end for moving the flapper valve; a cam follower supported by the other end of said arm; first and second rotatable cam plates, at least one of said cam. plates having a first camming surface which, when engaged by said cam follower, causes said arm to maintain said flapper valve in said first position, each of said cam plates having a second camming surface which, when engaged by said cam follower, causes said arm to maintain said flapper valve in said second position; means for biasing said cam follower into engagement with said first and second cam plates; means for rotating said first and second cam plates; and means for connecting said cam plates such that the degree of registration between said second camming surfaces can be varied thereby varying the amount of time the flapper valve is in the second position.

2. Apparatus of claim 1 in which said second camming surfaces cause said flapper valve to be in said second position for a shorter period of time than said valve is in said first position when said surfaces are in complete registration and cause said flapper valve to be in said second position for a longer period of time than said valve is in said first position when said surfaces are completely out of registration.

3. Apparatus of claim 1 in which said first and said second cam plates have identical profiles.

4. Apparatus of claim 1 in which said means for connecting said cam plates comprises: an arcuate slot formed in said first cam plate and having a radius of curvature coinciding with the axis of rotation of said first cam plate; a bore formed in said second cam plate; and a bolt for engaging said first cam plate while extending through said slot and being connectably received within said bore.

5. Apparatus of claim 1 in which said means for rotating comprises an electrical unidirectional drive motor.