Method and apparatus for ceiling ventilation

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METHOD AND APPARATUS FOR CEILING
VENTILATION

This is a continuation of application Ser. No. 08/485,726 filed on Jun. 7, 1995 abandoned. 5

BACKGROUND OF THE INVENTION

This invention relates to a method and means for improving mechanical ventilation for livestock confinement buildings. 1°

A good ventilation system for livestock confinement buildings is essential for the health, well-being, and development of the confined animals. The ventilation system accomplishes the following three tasks: air exchange between the interior of the building and the exterior envi- 15 ronment to replenish oxygen and to remove moisture, waste gases and dust, air circulation within the building to produce an evenly tempered, uniform living environment for the animals, and heating or cooling to maintain the temperature within a chosen optimum range for the animals. 20

Two alternative types of ventilation systems are generally used to provide ventilation for animals, either natural ventilation systems or mechanical ventilation systems.

Natural ventilation systems rely upon the wind passing 2J through openings, such as windows or continuous openings along the sides of the building, and upon thermal currents created by the natural buoyancy of heated air within the building. Fresh air therefore enters the building and circulates through the confinement space and then exits on the 3Q down-wind side of the building and through vents in the ridge or other high point in the roof, removing moisture, waste gases, and dust with the exiting air stream. Although natural ventilation may be less costly to construct and to operate, ventilation reliability is unpredictable because its 35 operation is greatly dependent upon the forces of nature, over which the system generally has only minimum control.

Mechanical ventilation systems use powered exhaust fans to slightly reduce the air pressure within the building and thereby causing fresh air to be drawn into the space to be 40 ventilated while the fans discharge the moisture, gases, and dust from the building. The incoming fresh air is conveyed into the building through specific air inlet locations. The air inlet locations are chosen by one skilled in the art of ventilation according to specific engineering practice so that 45 these locations cooperate in developing good fresh air distribution throughout the building.

The air inlet locations are generally equipped with devices called air inlets that attempt to regulate the volume flow of fresh air, its incoming speed, and its direction into the 50 building. The air inlet regulates the volume flow of the fresh air to balance the fresh air requirement of the animals with the need to conserve or expel heat from within the building and to proportionately match the variable exhaust capacity of the exhaust fans. The air inlet controls the speed of the 55 incoming air to regulate the distance that the air stream penetrates into the ventilated space and the circulation pattern that results within that space. The air inlet also directs the incoming air into the building. In the wintertime the goal is to maximize mixing time for the incoming cold 60 air with the warm interior air and therefore avoid stressful drafts. In summertime the goal is to optimize the cooling effect of the incoming fresh air on the animals.

Mechanical ventilation systems use a wide variety of means and methods for air inlets including both automatic 65 self-regulating air inlets that respond only to the slight vacuum created by the exhaust fans and also manually set

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and power-driven air inlets with regulation devices which sense the operation of the exhaust fans or the vacuum that they create. Automatic self-regulating air inlets are generally preferred over manually set air inlets because the latter require continuous supervision labor and are preferred over power-driven air inlets because the latter are more costly, complicated, and less reliable in operation.

Automatic self-regulating air inlets may be designed specifically for use in the ceiling, on the sidewall, or with slots in the juncture between the ceiling and sidewall of the building.

The proper operation of automatic air inlets is generally effected by wind pressure. This wind pressure, by its very nature, is variable and unpredictable. Its effect on the performance of air inlets and, by extension, the ventilation system can be seriously detrimental to achieving the goals of the ventilation system.

This invention relates to specific methods and means that define the design and construction of an improved automatic self-regulating air inlet device which minimizes the effect of wind pressure on air inlet performance and which is positioned in the ceiling joists, between the roof and the confinement space, of confinement buildings.

SUMMARY OF THE INVENTION

Therefore, a primary objective of the present invention is the provision of an improved method and means for ventilating a livestock confinement building.

A further objective of the present invention is the provision of an improved method and means for ventilation which accurately and proportionately controls the volume of the incoming air stream.

A further objective of the present invention is the provision of an improved method and means for ventilation which accurately controls the speed of the incoming air stream to maximize its mixing time and tempering effect with the warmer interior air when the incoming air stream is cold in winter, to optimize its cooling effect in summertime, and to provide a smooth automatic transition between these two operating extremes.

A further objective of the present invention is the provision of an improved method and means for ventilation which accurately controls the direction of the incoming air stream so that the direction is generally along the ceiling. When the volume of incoming air is reduced in wintertime, a near constant velocity will promote mixing and tempering of the colder incoming air with the warmer air higher in the room. When the volume of air is increased in summertime, a near constant velocity promotes cooling of the animals by more immediate contact and a greater volume of circulating air.

A further objective of the present invention is the provision of an improved method and means for ventilation which minimizes the effect on air inlet performance of exterior wind pressure on the air inlet.

A further objective of the present invention is the provision of an improved method and means for ventilation which is totally automatic in operation without the need for manual or power-assisted supervision or adjustment.

A still further objective of the present invention is the provision of an improved method and means for ventilation of a livestock confinement building in order to provide optimum air distribution which minimizes stagnate air spaces and localized drafts while providing optimum air exchange within the confinement living space.

Another objective of the present invention is the provision of an improved method and means for ventilation within a 3

livestock confinement building which is economical, efficient in use, automatic in operation, and which results in a desirable and durable assembly.

The present invention utilizes a ceiling inlet having a cylindrical inlet sidewall including an inlet aperture and an 5 outlet aperture, and a flange located adjacent the outlet aperture. Mounted adjacent the outlet aperture is a baffle. This baffle is connected for piston-like movement and can move between a first closed position wherein no air is allowed to enter the livestock confinement space and a 1° second open position wherein air flows into the livestock confinement space. The baffle is also hinged so that a first and second baffle portions can fold down for substantially undirected and uninterrupted airflow into the confinement space. 15

In order to ensure the movement of the baffle is constant and linear respective to the inlet housing, the baffle shaft is supported for linear movement by a guide tube which is connected to the cylindrical sidewall. The upper end of the baffle shaft is connected to a cantilever bar. The cantilever 20 bar is also connected to a biasing means spring, while the bar itself is supported for pivotal movement. The biasing means spring, through its mechanical connection to the baffle shaft, exerts a force on the baffle which tends to hold the baffle in a closed position until air pressure difference between the 25 confinement space and the external environment is sufficient to move the baffle toward its second, or open, position.

Due to the positioning of the baffle adjacent the outlet area of the cylindrical inlet housing, the baffle also acts as a directional member forcing incoming air into a flow direction along the ceiling of the confinement space. Due to the invention's unique construction, regardless of airflow velocity, the baffle imparts substantially the same influence on the direction of the air flow. However, as the volumetric

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rate of air flow changes, the baffle will adjust and tend to force the air flow velocity towards a consistent predetermined rate in the confinement space in order to project the fresh air further into the confinement space and into the air mass above the animals that contains the highest heat and moisture content.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a ceiling ventilation inlet.

FIG. 2 is a perspective cutaway view of FIG. 1.

FIG. 3 is an elevational view of a ceiling ventilation inlet with baffle sections hinged open.

FIG. 4 is a sectional view taken along line 4—4 of FIG. 3 with the baffle in a closed position.

FIG. 5 is a sectional view with the baffle shown in a 50 slightly open position.

FIG. 6 is a sectional view with the baffle shown in the open position.

FIG. 7 is a sectional view showing an overall ventilation system and its effect in a livestock confinement building. 55

FIG. 8 is an isolated view of the cantilever mechanism defining relative dimensions used in describing the present invention.

FIG. 9 is a perspective cutaway view of an alternative embodiment of the present invention. 60

FIG. 10 is a sectional view defining certain dimensions of a preferred embodiment.

DETAILED DESCRIPTION OF THE

PREFERRED EMBODIMENT 65

Referring to the drawings, numeral 10 generally refers to a ceiling ventilation inlet of the present invention which

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comprises a cylindrical sidewall 12 having an air inlet aperture 14 and an air outlet aperture 16. A flange 18 is formed integrally with the air outlet aperture 16 of the ceiling inlet 10. Flange 18 is designed to engage the ceiling of a livestock confinement space.

As best shown in the cut-away view of FIG. 2, a baffle 20 of approximately the same size and shape of the air outlet aperture 16 is positioned adjacent thereto. Baffle 20 is connected to baffle shaft 22, a hollow cylindrical tube which is supported for linear movement in a generally vertical orientation. Baffle shaft 22 includes an upper guide channel 24 and a lower guide channel 26 cut at different heights in the longitudinal dimension of baffle shaft 22. Upper guide rod 28 extends through upper guide channel 24 and is fixed at both ends to the cylindrical sidewall 12. Lower guide rod 30 extends through lower guide channel 26 and also is coupled at both ends to the cylindrical sidewall 12. Because the upper and lower guide channels 24, 26 are not colinear along the longitudinal dimension of baffle shaft 22, the use of the upper and lower guide rods 28, 30 prevents all but vertical movement of baffle shaft 22 relative to ceiling inlet 10.

Cantilever bracket 32 is attached to cylindrical sidewall 12 and is generally C-shaped with the center portion of the "C" being fitted against sidewall 12. Extending downwardly from the upper portion of the C-shaped bracket 32 is the first and second pivot plates 34, 36. First and second pivot plates 34, 36 are spaced apart so that cantilever bar 38 can be positioned therebetween. Pivot pin 40 extends from the first pivot plate 34 to the second pivot plate 36 through an aperture (not shown) in cantilever bar 38. Cantilever bar 38 then pivots about pivot pin 40.

Connector pin 42 connects baffle shaft 22 to the cantilever bar 38. Connector pin 42 is hooked into baffle shaft 22 at baffle connection point 44. Connector pin 42 is attached to cantilever bar 38 at cantilever connection point 46.

At the opposite end of cantilever bar 38, the biasing means connector point 48 is shown. Biasing means 50 is connected at biasing means connector point 48 of the cantilever bar 38 and extends to eyebolt 52. Eyebolt 52 is connected to the lower portion of bracket 32.

Additionally, baffle 20 can be manually opened to allow constant air flow without change of direction or velocity. Baffle 20 includes hinges 54, 56 which are connected to hinge plate 58. By opening the baffle 20 as shown in FIG. 3, fresh air can be injected into the confinement space without the effect of the direction and velocity control of the present invention.

The general operation of the ceiling inlet 10 is best shown in FIG. 7. Livestock confinement building 60 is shown having an exterior air inlet 62. When the air pressure within the livestock confinement building 60 is less than the air . pressure externally, air is drawn into the exterior air inlet 62 and subsequently through the ceiling inlet 10 as shown by the arrows in FIG. 7. This difference in air pressure is achieved, as stated earlier, by either natural methods or mechanical systems such as the power exhaust fan 64. Once air is drawn into the ceiling inlet 10 and its housing 12 the air pressure difference should be sufficient to cause the baffle 20 to move towards an open position and allow air to escape from the area created between the air outlet aperture 16 and baffle 20. The size of this air outlet area will depend on the distance from baffle 22 to the air outlet aperture 16. Because the air outlet area extends 360 degrees around the ceiling inlet, ventilation in each and every direction is enhanced and air exiting the housing 12 travels in a 360 degree pattern of dispersion.

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In operation, and specifically referring to FIGS. 4 through 6, the ceiling inlet 10 of the present invention accomplishes at least all of its stated objectives by constantly altering the size of the air outlet area to compensate for a lower or higher fresh air volumetric flow rate into the confinement building. 5

FIG. 4 shows baffle 20 in a closed position, covering air outlet aperture 16 and resting against flange 18. The structure shown in FIG. 4 will exist typically when the air pressure inside the housing sidewall 12 is lower than or substantially equal to the air pressure inside the livestock 1° confinement space 66. Should the air pressure within the cylindrical sidewall 12 rise to a level where it is greater than the air pressure in the livestock confinement space 66, the resulting pressure will force baffle 20 and baffle shaft 22 to move in a linear fashion downwardly thereby creating an air :5 outlet area. This situation is shown in FIGS. 5 and 6. The air outlet area in FIG. 5, shown best as the area between flange 18 and baffle 20, will increase (to that size shown in FIG. 6) should the air pressure within the housing 12 increase.

In general, however, in order to optimize ventilation and 20 decrease unnecessary drafts, a flow velocity of approximately 1000 feet/min. of air entering the livestock confinement space 66 is desired. In order to achieve a near constant flow velocity without manual adjustments, it is important that baffle 20 move up and down between its open and 25 closed position to compensate for different air pressures within the cylindrical sidewall 12. Therefore, as shown in FIG. 5, air pressure in the housing is just slightly higher than the pressure in the confinement space 66, the baffle will move slightly downward and provide a minimal air outlet 30 area thereby forcing the fresh air entering the confinement space 66 to travel at the desired velocity into the confinement space 66. However, should the air pressure within cylindrical sidewall 12 be relatively high, baffle 20 will move even more downwardly to an open position so as to 35 compensate for the higher air pressure difference and allow more air to escape at the same or similar velocity. Again, while a velocity in the range of 500 to 1600 feet/min. is appropriate, it is believed the optimum air velocity rate is approximately 1000 feet/min. 40

The balance force needed to resist the flow force acting on the baffle can be determined by using standard flow equations accepted by those skilled in the art of ventilation. The parameters used in the equations are shown in FIG. 10 and 4J listed in Table 1.

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fpm, the resultant mixing of fresh air and confinement building air is insufficient for good ventilation. If the exit air velocity is above 1600 fpm, the pressure difference between the interior building space and the exterior environment space is greater than the pressure difference created by the ventilation fans. The result of this latter condition is inadequate air supply for the animals in the confinement space.

A proportionality constant, Kc, is defined as the difference in forces between the open, FQ, and closed, Fc, baffle locations divided by the deflection, d, (or downward distance) of the baffle.

K=(F0-Fc)l(d0-dc)

The flow force proportionately enlarges the baffle deflection until the exit opening area equals the inlet opening area. When this latter condition exists, the baffle is at its maximum open distance and the inlet opening area, not the baffle, regulates the volumetric amount of air entering the confinement space. As the inlet opening area increasingly controls the volumetric air flow, the rate of increase of the pressure force on the baffle is proportionately reduced and becomes a function of the inlet area.

As defined in FIG. 10, the maximum baffle deflection, d„„T, is determined to be:

If the exit air velocity is maintained absolutely constant, the proportionality constant must be zero. If a designed relationship between exit air velocity and baffle deflection is chosen, the proportionality constant is calculated using the equation below.

K=V2pa x(DJ>ID,2)(Vmax2-Vmi„2)

where:

Vmj„=Exit Air Velocity when baffle begins to open Vm(n.=Exit Air Velocity when baffle is at desired opening (d) and;

Vml„ and Vm(n. range between 500 fpm (100 in/s) and

1600 fpm (320 in/s) d ranges from 0 to dmax

The design objective of the present invention using the foregoing design equations and concepts with a defined exit air velocity range is an inlet that functions automatically throughout the entire operating year. The minimum exit air velocity occurs during the winter season when volumetric air requirements are reduced owing to lower pressure differences between the interior confinement space and the exterior environment. At these low volumetric wintertime requirements, if the intake design operates to develop high pressure differences, unplanned air infiltration into the building through cracks and other openings causes undesirable drafts and improper fresh air distribution.

For summer ventilation, a maximum exit air velocity is chosen to develop the maximum volume of airflow to the confinement space at an acceptable pressure difference. The goal for this choice is optimum ventilation efficiency.

If the values below are used in determining the proportionality constant Kc, the range can be shown to be:

0<Kc<166.154xlCT3* (DJ3/(D,.)2

where: