"Condensate Drain Pan for an Evaporator Unit"

Technical Field

This invention relates generally to evaporator units for air conditioning systems and, more particularly, to a condensate drain pan arrangement and construction.

Background Art

In many commercial air conditioning, heating and ventilating systems, conditioned air is discharged into an internal space through an air distribution or conditioning unit. For example, one general type of air conditioning system, often referred to as a split system, includes separate indoor and outdoor units. The outdoor unit includes a compressor, a heat exchanger and a fan. The indoor unit includes a heat exchanger and a fan and is referred to as an evaporator unit. In operation, the indoor fan draws air into the evaporator unit, through an inlet thereof, and forces the air over the heat exchanger and then out of the evaporator unit, through an outlet opening therein.

The outdoor fan draws outdoor air into the outdoor unit, and circulates it over the outdoor heat exchanger and then back out to ambient. At the same time, a compressor causes a refrigeration fluid to circulate through and between the indoor/outdoor heat exchangers. At the indoor heat exchanger, the refrigerant absorbs heat from the air passing over that heat exchanger to cool the air. At the same time, at the outdoor heat exchanger, the air passing over the heat exchanger absorbs heat from the refrigerant passing therethrough.

Split type air conditioning units of this type are typically manufactured in a wide range of cooling capacities. In manufacturing such units, particularly as the units become larger, the fabrication and assembly of the various components becomes onerous and cumbersome. Typically, the larger the unit the more components are required and the more fasteners are required in order to assemble all of the components. It is considered extremely desirable to minimize the number of components and fasteners required in the fabrication and assembly process.

A further benefit to the conditioning of the indoor air which occurs with such an air conditioning unit is the removal of undesired humidity in the air as the air is passed by the indoor heat exchanger. This dehumidification results in an accumulation of waste as humidity condenses on the cold indoor heat exchanger coils. It is accordingly necessary to collect the removed water and divert it to an appropriate disposal point.

Commonly, the indoor unit of a split system is mounted on the floor of a room against a wall thereof. In some situations, however, it is desirable to place the indoor unit in another location, such as on the ceiling of the room. It should be appreciated that an indoor unit which may be mounted in either of the above-mentioned floor mounted or ceiling mounted positions while still providing the ability to collect the condensate from the unit, would be extremely desirable.

An indoor unit for an air conditioning system which may be mounted as a floor, ceiling or wall mount is shown and described in U.S. Patent

No. 6,321,556. However, the unit as shown in this patent includes two different condensate collection pans to accommodate the various installation possibilities.

Disclosure of the Invention An evaporator unit for an air conditioning system includes a housing having a back panel and a front section defining an air inlet and an air outlet. The housing defines an air flow path through the unit extending from the inlet to the outlet. An evaporator coil is supported in the housing and within the air flow path. The unit includes an evaporator fan for causing air to flow along the air flowpath and through the evaporator coil where the air is cooled and water is removed therefrom, resulting in condensation.

A single drain pan is provided for collecting condensate with the drain pan being so constructed and oriented that the condensate will collect therein whether the unit is in a vertical orientation or a horizontal orientation. The drain pan is formed of a combination of a core, which is formed of a polyurethane material, and a shell, which is formed of an ABS material, and which is secured to the inside of the core to form that part of the drain pan which is exposed to the condensate. The core and the shell may be secured together by way of an adhesive, but preferably, the two elements are integrally formed during the molding process. The shell has a pair of troughs near one edge thereof which act to collect the condensate and to conduct the flow of condensate from the pan. One of the troughs is so constructed and disposed as to be active when the unit is in a vertical orientation and the other trough is so disposed and constructed as to be active when the unit is in the horizontal orientation. A drainage fixture is attached to the drain pan so as to fluidly

communicate with the troughs in such a manner that it is always at a lower elevation than the troughs when the unit is either in the horizontal or vertical orientation. The drainage fixture includes an inlet channel for each of the two troughs and baffles to restrict the flow of condensate passing into the drainage fixture.

The unit housing has a bottom wall and a back wall with each having an opening therein. Tubing is attached to the drainage fixture and is selectively passed through one of the openings to provide fluid communication from the drain pan to a location outside of the housing. For installations where gravity alone will not allow drainage from the tubing, a condensate pump is provided. A collecting sump and a sensor is also provided to responsively activate the pump.

Brief Description of the Drawings

Fig. 1 is a perspective view of an evaporator unit as installed in a vertical orientation in accordance with one embodiment of the present invention.

Fig. 2 is an exploded view thereof.

Fig. 3 is a front view thereof. Fig. 4 is a sectional view thereof as seen along lines 4-4 of Fig. 3.

Fig. 5 is a sectional view thereof as seen along lines 5-5 of Fig. 3.

Fig. 6 is an expanded view of a portion of Fig. 5 as indicated.

Fig. 7 is a front view of the evaporator unit as installed in a horizontal disposition. Fig. 8 is a sectional view thereof as seen along lines 8-8 of Fig. 7.

Fig. 9 is a sectional view thereof as seen along lines 9-9 of Fig. 7.

Fig. 10 is an expanded view of a portion thereof as seen in Fig. 9. Fig. 11 is a perspective view of the drain pan. Fig. 12 is an expanded view of the drainage fixture portion thereof. Fig. 13 is an exploded view of the drain pan and its drainage fixture.

Figs. 14 - 17 are various view of the drainage fixture.

Detailed Description of the Invention

The present invention is applied to an evaporator unit 11 which is shown in Fig. 1 as installed in a generally vertical orientation with its rear side

12 being installed against a wall 13 and its bottom side 14 being installed adjacent to the floor 16. Although the unit is also designed to be alternatively installed in a generally horizontal position with its back side 12 resting against the ceiling and its bottom side 14 resting against the side wall 13 as will be described hereinafter, it will presently be described in the context of the vertical orientation as shown. Thus, in addition to the back side 12 and the bottom side

14, the evaporator unit 11 has a front side 17, a top side 18, a left side 19, and a right side 20.

On the front side 17 of the evaporator unit 11 there is provided a front panel 36 behind which is an evaporator compartment that contains an evaporator coil. Below the front panel 36 is a grill structure 39, behind which has an air intake opening which fluidly communicates with a blower which draws air inwardly through the grill structure 39 and over the evaporator coil to be cooled. The cooled air is then discharged from a discharge opening 25 in the top side 18.

Referring to Fig. 2, the evaporator unit is shown in an exploded view to include all the various components prior to assembly. The sequence and manner of assembly will now be described.

A back panel 21 forms the primary structural component and a portion of the housing of the evaporator unit. An upper closure assembly 22 is secured to the back panel 21 by first engaging an upper edge thereof over an upper edge of the back panel 21 and then securing the two components together with fasteners 23. The left and right internal side assemblies, 24 and 26, are attached to the back panel 21 by fasteners. The fan assembly 27 is then secured to the lower portion of the back panel 21 by fasteners 28.

The next step in the assembly process is to install the evaporator coil 29 into the housing by placing its ends in the respective left and right internal side assemblies 24 and 26. The evaporator coil 29 is then secured in its installed position by a single screw at each end thereof which passes through the internal side assembly and into a tube sheet at the end of the evaporator coil 29. The evaporator coil 29 is so disposed within the evaporator compartment, which is partially defined by the back panel 21 and the left and right internal side assemblies 24 and 26. However, it is still necessary to close the ends of the evaporator compartment to prevent the flow of air therethrough. This is accomplished by way of left and right closure elements 31 and 32 which are simply placed in position without fasteners and then are held in place by engagement with the drain pan 33 which further defines the evaporator compartment. The drain pan 33 is secured in place by a fastener in each end to secure the respective left and right internal side assemblies 24 and 26 to the

drain pan 33. A drain hose 34 is attached to a drainage fixture of the drain pan 33. A front panel 36 is then placed over the drain pan 33. A drain hose 34 is attached to a drainage fixture of the drain pan 33. A front panel 36 is then placed over the drain pan 33 and secured in place by fasteners, attaching it to both the left and right internal side assemblies 24 and 26 and also to the fan deck portion of the back panel 21.

Returning to the sides of the unit, a control box 37 is installed by snap fit into the left internal side assembly 24 and a stepping motor 38 is also secured to the side assembly 24.

The blower compartment, which is partially formed by the lower portion of the back panel 21 and by the fan assembly 27, has an air intake opening therein. This intake opening is partially closed by way of a grill 39 into which a plurality of filter elements 41 are placed.

The next step is to connect the stepping motor 38 to a horizontal louver mechanism on the upper closure assembly 22 and the horizontal louver 42 is secured at its ends to the left and right internal side assemblies 24 and 26 and, in its intermediate portion, to the upper closure assembly 22. The left and right end caps, 43 and 44, are then secured to the respective left and right internal side assemblies 24 and 26 respectively, to complete the assembly process.

A front view of the evaporator unit is shown in its vertically oriented installation in Fig. 3. The details of the internal components are shown

in the sectional views of Figs. 4-6.

With the unit disposed in such a vertically oriented position, the fan assembly 27 draws the air to be cooled horizontally inwardly through the grill 39 and up into an evaporator compartment 46 where it passes over the evaporator coil 29 to be cooled. It is then discharged upwardly and outwardly through the discharge opening 25. In addition to cooling the air passing through the evaporator coil 29 the air may also be dehumidified by removing some of the moisture from the air and causing it to condense on the surface of the evaporator coil 29.

As will be seen in Figs. 4-6, the lower end of the evaporator coil 29 is captured in the lower end of the drain pan 33 such that the condensation that forms on the evaporator coil 29 tends to collect in the groove or trough 47 at the lower end of the drain pan 33. The condensate then drains to one end of the trough 47 where a drainage fixture 48 is installed as will be described hereinafter. From the drainage fixture 48 the condensate drains out through a discharge tube 49, the drain hose 34, and eventually to a location outside the building.

As described hereinabove, the drain pan 33 and condensate drainage system has been described as it functions when the unit is installed in a vertical orientation against a wall. As shown in Figs. 7-10, the same unit is shown as installed in a horizontal disposition on the ceiling of a room. In such a disposition, the rear side 12 is disposed against a ceiling, and the conditioned air is discharged substantially horizontally from the discharge opening 25. As will

be seen, the drain pan 33 is now disposed in a substantially horizontal orientation with its second trough 51 being at a lower elevation such that condensate from the evaporator coil 29 tends to collect in the second trough 51 and pass to the drainage fixture 48. The condensate then tends to flow from the drainage fixture 48, through the discharge tube 49 and out the drain hose 34. Rather than exiting from the rear side 12 of the unit as in the vertical orientation installation, the drain tube 34 passes through the bottom side 14 of the unit as shown. From there, it would normally pass through tubing downwardly through a wall and eventually to the outside.

Considering now the drain pan 33 and the details of its construction, the drain pan 33 and its associated drainage fixture 48 are shown in Figs. 11 and 13. The drain pan has a bottom 52, front and back upstanding walls 53 and 54, and upstanding side walls 56 and 57 that, collectively, form a container for the condensate that is to be collected from its formation on the evaporator coil 29. As described hereinabove, its first and second troughs 47 and 51 are formed near its back wall 54, and the bottom 52, when shown in the horizontal disposition as seen in Figs. 7-11, slopes slightly downwardly toward the trough 51. This sloping disposition is better shown in Figs. 8 and 9.

As shown in Fig. 13, the drain pan 33 is formed of two elements, an outer shell 58 and an inner liner 59. The outer shell 58 is composed of a light weight, polyurethane material, and the inner liner 59 is composed of a water resistant ABS material. The shell 59 is relatively thin in thickness and conforms to the shape of the upper surface of the outer liner 58. The outer shell 58 and inner liner 59 may be formed separately with the two being then secured

together by an adhesive or the like. Alternatively, they may be formed, as an integral unit by a process such as molding or the like.

As will be seen in Figs. 11 and 13, near the side wall 57, and in line with the first and second troughs 47 and 51 , a cavity 61 is provided for receiving the drainage fixture 48 which may be secured within the cavity 61 by an adhesive or the like. The drainage fixture 48 is shown in its installed position in

Fig. 12 and in an uninstalled position in Figs. 14-17.

The drainage fixture 48 is preferably composed of a light weight, plastic material and comprises a body 62 having a back wall 63, side walls 60 and 64, front wall 65, and a bottom 66, all of which form a reservoir 67. An opening 68 is formed in the back wall 63 and the discharge tube 49 is fluidly connected thereto to drain away the condensate as previously described.

Leading into the reservoir 67 are a pair of bridge like structures 71 and 72 which, at different levels, define inlet channels 73 and 74, respectively. (See Figs 14 and 15, in particular). The channel 73 is aligned with the first trough 47 and the channel 74 is aligned with the second trough 51. The flow of condensate flows from the first trough 47 through the inlet channel 73 and into the reservoir 67 when the unit is oriented in a vertical disposition. When the unit is horizontally disposed, the condensate will flow from the second trough 51, through the inlet channel 74, and into the reservoir 67.

Recognizing that the flow along the troughs could be substantial at times, provision is made to prevent the flow stream from blowing past the side

wall 64 of the reservoir 67. Thus, aligned with the inlet channel 73 is a baffle 76, and aligned with the inlet channel 74 is a baffle 77 for the purpose of breaking up the flow pattern and allowing the condensate to flow around the baffles and through the opening 68.