US3417977A

US3417977A - Air control system for heating unit

Info

Publication number: US3417977A
Application number: US614991A
Authority: US
Inventors: Charles E Nelson
Original assignee: Mammoth Industries Inc
Current assignee: Mammoth Industries Inc
Priority date: 1967-02-09
Filing date: 1967-02-09
Publication date: 1968-12-24
Anticipated expiration: 1985-12-24

Description

Dec. 24, 1968 c. E. NELSON AIR comm. SYSTEM FOR HEATING UNIT 2 Sheets-Sheet 1 Filed Feb. 9, 1967 N hhw INVENTOR. CHARL Est. NELsaN AvToRNEY;

Dec. 24, 1968 c. E. NELSON 3,417,977

AIR CONTROL SYSTEM FOR HEATING UNIT filed Feb. 9, 1967 2 Sheets-Sheet 2 W UN a W DN 1 INVENTOR. CHARL Es fiNELsaN MM WW,

A 1' T n/v5 Y:

United States Patent 3,417,977 AIR CONTROL SYSTEM FOR HEATING UNIT Charles E. Nelson, Excelsior, Minn., assignor to Mammoth Industries, Inc., Minneapolis, Minn., a corporation of Minnesota Filed Feb. 9, 1967, Ser. No. 614,991

11 Claims. (Cl. 263-19) ABSTRACT OF THE DISCLOSURE An air flow control system for a heating unit having a line direct fired gas burner. Movement of air around the burner is controlled by a pair of linearly movable profile plates located adjacent the upper and lower sides of the shielding and mixing walls of the burner. The profile plates are part of a system of dampers in the heating unit to regulate the ratio of fresh air and return air discharged by the heating unit. A control unit is part of a damper control system which selectively moves the profile plates to open and closed positions in conjunction with changing the positions of fresh air intake damper blades and return air damper blades whereby a substantially constant velocity of air flows past the burner to provide uniform firing characteristics.

Gas burners have been developed for direct fired operation in an air stream to heat the air in the stream and utilize part of the air of the air stream as a supply of air for combustion of gas discharged by the burner. Direct fired line burners of this type are arranged downstream of the fresh air intake of the heating unit and heat fresh air flowing over the burner. These heating units are usually provided with fixed profile plates to regulate the flow of air across the burner for a constant amount of air. These profile plates are not closely correlated with the combustion area of the burner so as to effectively control the flow of varying amounts of air past the bumer. When used to change the volume of air which flows past the burner rotating damper blades deflect and cause turbulence of the air flow causing incomplete combustion of the gases. An example of a direct fired line burner is shown in US. Patent No. 3,051,464.

Briefly described, the air control system of the present invention is used in conjunction with a line direct fired gas burner to maintain the velocity of air flowing past the burner substantially constant regardless of the volume of the air flowing across the burner. The control system has a pair of movable doors or profile plates located adjacent the upper and lower sides of the mixing walls of the burner. The profile plates extended in a transverse direction relative to the flow of air across the burner do not deflect or cause turbulence of the flow of air thereby promoting uniform heating of air and complete combustion of the gases. The profile plates move in conjunction with the movement of dampers across the fresh air intake of the heating unit as well as similar dampers across the return air duct whereby a substantially constant amount of air flows through the heating unit at all times. The positions of the dampers and the profile plates are regulated by a control unit located in the room to be heated. The control unit is operable to change the percentage of fresh air relative to return air from about 25% fresh air to 100% fresh air. The burner has a separate control which at 25% or less fresh air it will automatically shut off whereby the heating unit circulates a mixture of unheated fresh air and return air. With this control, a maximum amount of return air may be circulated through the heating area during the non-occupied periods of a building.

In the drawings:

FIGURE 1 is a diagrammatic view of a fresh air heat- 3,417,977 Patented Dec. 24, 1968 See ing unit equipped with the air flow control structure of this invention;

FIGURE 2 is an enlarged sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is an enlarged sectional view taken along the line 33 of FIGURE 2 showing the profile plates on opposite sides of a linear direct fired burner in closed positions as at minimum fresh air flow through the heating unit; and

FIGURE 4 is a view similar to FIGURE 3 showing the profile plates in open positions as at maximum fresh air flow through the unit.

Referring to the drawings, there is shown in FIGURE 1 a heating system indicated generally at for supplying temperature controlled air to an enclosed space 11, as a room in a building. System 10 has a heating unit, indicated generally at 12, which discharges air to a duct 13 connected to space 11 and withdraws return air through duct 14 from space 11 into the heater unit.

Heating unit 12 is a furnace having a line direct fired burner indicated generally at 16, such as the line burner disclosed in US. Patent No. 3,051,464. Burner 16 has a transverse manifold 17 which carries diverging shielding and mixing

walls

18 and 19 forming a transverse mouth 21 which serves as a combustion chamber for the flame 22. Shielding and

mixing walls

18 and 19 each have a plurality of

openings

23 and 24, shown in FIG- URES 3 and 4, for directing air into the combustion chamber. Manifold 17 is coupled to a gas line 26 which supplies the gaseous fuel to the burner from a gas control unit 25.

As shown in FIGURE 2, control unit has a servo motor 25A connected to a butterfly-type valve 25B located in gas line 26. A line operatively couples servo motor 25A with servo motor 61 used to change the positions of the

profile plates

48 and 49. In operation servo motor 61 sends a signal to motor 25A proportioning maximum gas supply to fresh air volume.

Heating unit 12 has a housing or casing including a top wall 27 and a bottom wall 28 which are separated at one end by fresh air intake opening 29. A movable damper 31, as louvres or pivoted doors, extend across fresh air intake opening 29 and are selectively moved to open and closed positions by a servo motor 32. A linkage 33 operatively connects the servo motor with each of the damper doors. Fresh air indicated by arrows 34 flows past the doors through intake opening 29 toward the burner 16.

The movement of air past shielding and mixing

walls

18 and 19 of the burner is controlled by an air flow control indicated generally at 36. In general, the air flow control 36 functions to maintain a substantially constant volume of flow of air through the heater unit regardless of the ratio of fresh air and return air. This is accomplished by controlling the ratio of fresh air to return air moving into the heater unit in conjuction with changing the

areas

37 and 38 on opposite sides of the shielding and mixing

Walls

18 and 19 of the burner which regulate the flow of air indicated by arrows 39 and 41 over the burner into air receiving chamber 42. As shown in FIGURE 1, heater unit 12 has a blower 43 which circulates or drives the air through the housing discharging air indicated by arrow 44 into the duct 13, drawing return air indicated by arrow 45 through the duct 14, and drawing fresh air over burner 16. The amount of return air drawn into the heating unit is controlled by a movable damper 46, as louvers or pivotal doors, coupled by linkage 46A to a servo motor 47 operable to open and close damper .46.

As best shown in FIGURES 3 and 4, control 36 includes a pair of movable doors or

profile plates

48 and 49 located adjacent opposite sides of the outer ends of the shielding and mixing

walls

18 and 19 of the burner.

Plates

48 and 49 are postioned in the same plane adjacent

upright walls

50 and 51 spaced from the shielding and mixing

walls

18 and 19.

Areas

37 and 38 confine the fiow of air through the heating unit adjacent opposite sides of burner 16.

As shown in FIGURES 2 and 3, movable upper profile plate 49 has rearwardly directed

longtiudinal flanges

54 and 56 having aligned holes for accommodating a plurality of spaced support rods 52 secured at their lower ends to a transverse fiat beam 53. The opposite or upper ends of the rods 52 are mounted on frame structure on top wall 27. The lower profile plate 48 has similar flanges for accommodating a plurality of spaced upright rods 57 which are secured at their upper ends to a transverse flat beam 58 and at their lower ends to a frame structure secured on bottom wall 28.

Rods

52 and 57

guide profile plates

49 and 48 respectively for sliding movement in a common plane which is generally normal to the flow of air passing through and moving over shielding and mixing

burner walls

18 and 19. The plane of the

profile plates

48 and 49 is located in the general plane of the longi tudinal ends of the shielding and mixing

walls

18 and 19.

A drive indicated generally at 59 including a servo motor 61 functions to move

profile plates

48 and 49 selectively toward and away from opposite sides of burner 16

keeping areas

37 and 38 substantially equal. A linkage assembly indicated generally at 62 operatively couples servo motor 61 with the upper and lower profile plates so that the plates move together to simultaneously open or restrict

areas

37 and 38. As shown in FIGURE 2, linkage assembly 62 has a transverse shaft or rod 63 rotatably mounted on a plurality of spaced upright brackets 64 carried on bottom wall 28. Secured to spaced portions of rod 63 are forward arms 66. The middle section of rod 63 carries an upright arm 67. The outer ends of arm 66 are pivotally coupled to links 68 which are pivotally mounted to upper portions of lower profile plate 48 by a plurality of ears 70. The outer end of upright arm 67 is pivotally connected to a link 69 used to connect the outer end of a crank arm 71 secured to the drive shaft of servo motor 61.

Secured to opposite ends of transverse rod 63 are rearward arms 72 and 73 each carrying counterweights 74 and 76 at their outer ends to balance the weight of lower profile plate 48. Counterweights 74 and 76 may be longer and heavier depending on the size of profile plate 48.

Movement of the upper profile plate 49 is controlled by a similar linkage structure including a transverse rod or shaft 77 rotatably carried on a plurality of spaced brackets 78 secured to top wall 27. A plurality of forward projecting arms 79 secured to shaft 77 are each pivotally coupled to links 81. The outer ends of links 81 are pivotally connected to brackets 82 secured to lower portions of upper profile plate 49. Shaft 77 is rotated in conjunction with the rotation of shaft 63 by providing additional

forwardly projecting arms

83 and 84 at opposite ends of rod 77 and coupling the forward portions of these

arms

83 and 84 to downwardly projecting

rods

86 and 87. The lower ends of

rods

86 and 87 are pivotally attached to the outer ends of rearward arms 72 and 73 respectively whereby rotation of shaft 63 in one direction results in an equal and opposite rotation of shaft 77 in the opposite direction. The weight of the upper profile plate 49 is balanced by

counterweights

88 and 89 carried on the outer ends of rearwardly projected arms 91 and 92 respectively mounted on the opposite ends of shaft 77.

As indicated in FIGURE 3, arm 71 connected to the drive shaft of servo motor 61 is moved in the direction of the arrow 93 to move the

profile plates

48 and 49 away from each other and increase the

areas

37 and 38 adjacent the

walls

18 and 19 of burner 16. This increases the volume of fresh air moving past the burner with the result that the ratio of fresh air to return air is increased. Servo motor 61 is operable to hold the profile plates at any position between the closed positions as shown in FIGURE 3 and the open positions as shown in FIGURE 4.

A control unit 94 located within the closed area, as a room, is used to conjunctively operate motor 32 to open and close the fresh air inlet damper 31, motor 50 to open and close the damper 46 located across the return air duct 14, and operate servo motor 61 to control the positions of the

profile plates

48 and 49. The control unit 94 operates motors 32, 47 and 61 in conjunction with each other to maintain the flow of air through heating unit 12 at a substantially constant volume. The ratio of fresh air to return air changes in proportion to each other so that the volume of air moving through the heating unit is unaltered. Control unit 94 is provided with a manually adjustable dial 95 movable for changing the percentage of fresh air relative to return air from about 25% fresh air and 75% return air to fresh air and no return air. At 25% fresh air, burner 16 will automatically shut off whereby the heating unit will circulate return air mixed with unheated fresh air. This arrangement enables the enclosed area to have air circulation during periods, as a non-occupied period at nights, using the maximum amount of return air to reduce heating costs.

The linkages shown in the drawings conjunctively move

profile plates

48 and 49 toward and away from burner 16 in directions normal to the flow of air past the burner. These linkages are an example of one type of power transmitting structures which may be used to hold and change the positions of the profile plates. Other power transmitting means as a pair of screws having reverse threads driven by a reversible motor may be used to move the profile plates. In a similar manner other controlled structures for the fresh air intake damper 31 and return air damper 46 may be used to move these dampers from their open and closed positions.

While there have been shown and described the novel features of the invention as applied to a preferred embodiment it may be understood that changes may be made by those skilled in the art without departing from the spirit of the invention. The invention is limited only by the scope of the following claims.

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

1. In a heating unit having a direct fired burner, a fresh air intake opening, first means for opening and closing the intake opening, a return air passage, second means for opening and closing the air passage, third means located adjacent opposite sides of the burner for controlling the velocity of air past the burner, and control means operable to change the relative positions of said first means, second means and third means to change the ratio of fresh air to return air discharged by the heating unit while maintaining a substantially constant volume of air flowing through the heating unit and a constant velocity of fresh air moving past the direct fired burner.

2. The heating unit of claim 1 wherein said burner has rearwardly diverging transverse walls and said third means comprises fiat plates selectively movable toward and away from said walls in a direction generally normal to the flow of air past the burner.

3. The heating unit of claim 1 wherein the third means are profile plates selectively movable toward and away from the burner along a plane generally normal to the flow of air past the burner.

4. The heating unit of claim 1 wherein the third means are profile plates, and rod means slidably mounting a profile plate on opposite sides of the burner for movement toward and away from the burner.

5. The heating unit to claim 1 wherein said control means includes a first motor to move the first means to open and closed positions, a second motor to move the second means to open and closed positions, a third motor to selectively move the third means toward and away from the burner, and a control to conjunctively operate all of said motors.

6. The heating unit of claim 1 wherein said burner has shielding and walls and said third means comprises plates selectively movable toward and away from said walls.

7. The heating unit of claim 1 including means for controlling the supply of gas to the burner in conjunction with the operation of the control means to limit the maximum amount of gas supplied to the burner in proportion to the amount of fresh air moving past the burner.

8. In a heating unit, a direct fired burner, first plate means on one side of the burner, second plate means on the opposite side of the burner said first plate means and second plate means extended generally parallel to the burner in planes generally normal to the flow of air past the burner means mounting the first plate means and second plate means for selected linear movement in opposite lateral directions in said planes toward and away from the sides of the burner and control means for moving the first plate means and second plate means selectively toward and away from the sides of the burner.

9. The heating unit of claim 8 wherein the burner has rearwardly diverging shielding and mixing walls having outer ends and said first plate means and second plate means are spaced from and extend generally parallel to the outer ends of said shielding and mixing walls.

10. The heating unit of claim 8 wherein the control means includes power operated means to conjunctively move the first plate means and second plate means toward each other and away from each other.

11. The heating unit of claim 8 wherein the means mounting the first plate means and the second plate means are rod means slidably mounting said plate means for movement toward and away from the burner.

References Cited UNITED STATES PATENTS 2,171,275 8/1939 Morrison 263-19 3,064,720 11/1962 Keating et al 263-l9 3,178,161 4/1965 Yeo et a1. 263-49 3,199,848 8/1965 Harrison 126-110 CHARLES J. MYHRE, Primary Examiner.

E. G. FAVORS, Assistant Examiner.