Abstract:
A room air conditioner mounted on an external building wall, comprising an indoor unit, an outdoor unit and an interface unit. The indoor unit includes an indoor cabinet having a suction opening and outlet port for indoor air, an indoor heat exchanger, and an indoor fan. The outdoor unit includes an outdoor cabinet having a suction opening and outlet port for fresh air, an outdoor heat exchanger, an outdoor fan and a fan motor which engages the outdoor and indoor fans. The interface unit is mounted in the external building wall and includes a fan drive shaft engaged at the first end by the fan motor in the outdoor cabinet and engaging the indoor fan. The room air conditioner produces less noise compared to room air conditioners of the prior art, while requiring a significantly smaller exterior wall opening for installation, at the same time providing the flexibility to permit the introduction to the room of fresh outside air, the humidification of heated air in the heating mode, and the cooling or heating of air in more than one room.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to room air conditioners and, in particular, it concerns a design in which the room air conditioner is split into indoor and outdoor units interconnected using an interface unit mounted in an external wall. 
     It is known that the room air conditioner is an inexpensive, and thus desirable, alternative to the split-type air conditioning system in which the indoor and outdoor sections are separated physically and housed in separate cabinets. The installation of a room air conditioner requires a large opening in the external building wall, such that the room air conditioner is relatively noisy. Moreover, the capacity of a room air conditioner to heat or cool is generally limited to a single room because of space limitations and the additional noise produced by higher capacity units. 
     Split type air conditioners, unlike room air conditioners, generally produce characteristically lower noise levels in the room. Other potential advantages include the capacity to heat or cool several rooms, and a requirement for a relatively small opening in the external building wall. 
     A conventional room air conditioner will be described with reference to the drawings to particularly point out the characterizing features thereof. FIG. 1 is a sectional side view of a conventional air conditioner of the vertical type; FIG. 2 is a sectional view taken along the line II—II of FIG.  1 . As shown in these figures, the room air conditioner includes a cabinet  1 , the interior of which is divided into an indoor portion  10  and an outdoor portion  11  by a partition plate  12  secured to a bottom  9  of the cabinet  1 . A motor  5  is supported on a side of partition plate  12 , which faces the outdoor portion  11  of cabinet  1  and includes horizontally-disposed (i.e., parallel to bottom  9 ) rotary shaft  5   a.  A portion of rotary shaft  5   a  penetrates partition plate  12  and extends into the indoor portion  10 . 
     Mounted in the indoor portion  10  of cabinet  1  are a centrifugal fan  3  secured to rotary shaft  5   a,  a spiral casing  4  secured to partition plate  12  and disposed in enclosing relation to centrifugal fan  3 , and an indoor heat exchanger  2  located adjacent to spiral casing  4  on a side thereof opposite centrifugal fan  3 . Housed in the outdoor portion  11  of cabinet  1  are a propeller fan  6  secured to rotary shaft  5   a  of fan motor  5 , an outdoor heat exchanger  7  disposed in spaced juxtaposed relation to propeller fan  6 , a cover  15  interconnecting propeller fan  6  to outdoor heat exchanger  7 , and a compressor  8  mounted on the bottom  9 . Inlet ports  1   a  for introducing air into the interior of the cabinet are formed at opposite sides of the outdoor portion  11  of cabinet  1 . 
     In the room air conditioner described above, fan motor  5  and compressor  8  are actuated, such that a refrigerant compressed in compressor  8  has its temperature raised. The heated refrigerant is supplied to outdoor heat exchanger  7  and is cooled by a stream of air B produced by the rotation of propeller fan  6 . Subsequently, the cooled refrigerant is supplied to indoor heat exchanger  2 , where the refrigerant is expanded to cool indoor heat exchanger  2 , such that a stream of air A produced by the rotation of centrifugal fan  3  is cooled by indoor heat exchanger  2 . The refrigerant is then returned to compressor  8 . 
     There are several disadvantages associated with the above-described room air conditioner of the prior art, including: 
     a. The arrangement in which indoor heat exchanger  2 , centrifugal fan  3 , fan motor  5 , propeller fan  6  and outdoor heat exchanger  7  are interconnected necessitates mounting all the aforementioned components in a single cabinet  1  together with compressor  8 , resulting in the exposure of the room occupants to noisy mechanical system components. 
     b. The aforementioned arrangement in which indoor heat exchanger  2 , centrifugal fan  3 , fan motor  5 , propeller fan  6  and outdoor heat exchanger  7  are interconnected such as to necessitate the mounting of all the aforementioned components in a single cabinet  1  together with the compressor  8 , necessitates the provision of a large opening in the external building wall for installation of the air conditioner. 
     c. The effective cooling capacity of the air conditioner is generally limited to a single room, due to the high-level noise emissions and other design constraints. 
     There is therefore a recognized need for, and it would be highly advantageous to have, a low-cost room air conditioner having the advantages of split type air conditioners: low-level noise emissions, small opening requirement, and capacity to heat or cool more than a single room. 
     SUMMARY OF THE INVENTION 
     The present invention is a room air conditioner in which the indoor and outdoor sections are housed in separate cabinets and an interface unit is provided to interconnect various components including the heat exchangers, and to couple the indoor centrifugal fan to the fan motor housed in the external cabinet. 
     According to the teachings of the present invention there is provided, a room air conditioner in which noisy system components are housed external to the room, resulting in lower exposure of room occupants to noise. 
     According to yet another aspect of the present invention there is provided a room air conditioner with means for connecting the external and internal sections which permits the use of a minimally sized opening in the external building wall. 
     According to further features in the described preferred embodiments, the reduced noise exposure to room occupants provided, and the use of a minimally sized external building wall opening, permit the installation of a larger capacity room air conditioner which is capable of handling the air conditioning load of more than one room. This is accomplished in one preferred embodiment of the invention by means of connecting the interior unit air outlet port to a two-way damper and to air ducting so as to convey conditioned air to one or more additional rooms. 
     According to yet further features in the preferred embodiments, there is provided a room air conditioner having means of introducing fresh air into the room through the interface unit, while permitting installation using a minimally sized external building wall opening. According to yet further features in the preferred embodiments, there is provided a room air conditioner with many of the advantages of split-type air conditioners such as low noise production, high capacities capable of handling more than one room, and small external wall opening needed for installation, with minimal thermal efficiency losses due to the small distance between the indoor and outdoor heat exchangers. 
     According to yet further features in the preferred embodiments, there is provided a room air conditioner having means of using condensate water to humidify heated indoor air in the heating mode and to cool the exterior heat exchanger (condenser) in the cooling mode. 
     The present invention successfully addresses the shortcomings of the existing technologies by providing a design for reducing indoor noise levels of the room air conditioner and eliminating the need for providing a large installation opening in the external building wall. Consequently, the design allows the implementation of inexpensive, larger capacity room air conditioners that are capable of air conditioning more than one room. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
     In the drawings: 
     FIG. 1 is a sectional side view schematically showing a vertical type room air conditioner of the prior art; 
     FIG. 2 is a sectional view taken along the line II—II of FIG. 1; 
     FIG. 3 is a sectional side view of a room air conditioner comprising one embodiment of the invention; 
     FIG. 3 a  is an isometric view of the room air conditioner shown in FIG. 3; 
     FIG. 4 is a frontal view of a belt and pulley assembly for connecting the fan motor to the rotary shaft, according to one embodiment of the present invention; 
     FIG. 5 is a sectional side view of the interface unit according to a preferred embodiment; 
     FIG. 5 a  is an isometric view of the interface unit shown in FIG. 5; 
     FIG. 6 is a sectional view of the interface unit taken along the line I—I of FIG. 5; 
     FIG. 7 is a sectional side view of a room air conditioner according to one embodiment of the invention in which the indoor unit is disposed in a compact configuration and includes an absorbent pad for humidifying the conditioned air; 
     FIG. 7 a  is an isometric view of the room air conditioner shown in FIG.  7 . 
     FIG. 8 is a sectional plan view of a room air conditioner according to one embodiment of the invention, in which conditioned air is conveyed to more than one room. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a room air conditioner in which the interior and exterior sections are interconnected by an interface unit which connects the heat exchangers, transfers rotary motion from an electric motor positioned in the exterior unit to the fan positioned in the interior unit, transfers condensate water between interior and exterior sections, and provides a means to transfer fresh outside air to the fan casing in the interior unit for conveyance to the room interior. 
     The principles and operation of the room air conditioner according to the present invention may be better understood with reference to the drawings and the accompanying description. 
     Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawing. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting 
     Referring now to the drawings, FIG.  3  and FIG. 3 a  illustrate one form of the apparatus constructed in accordance with the present invention. As shown in FIG.  3  and FIG. 3 a,  one embodiment of the invention described herein consists of an interior unit  21 , an exterior unit  41  and an interface unit  24  for connecting interior unit  21  and exterior unit  41 . Mounted within interior unit cabinet  42  is a heat exchanger  30 , a condensed water collection pan  25  and drain tube  26 . In addition, water can be drained through tubes installed in the interface unit using a reversible water pump (see FIG.  7  and FIG. 7 a ), allowing use of the water for cooling the exterior unit  41  heat exchanger  38  in the air cooling mode or for humidifying the heated fresh air in the air heating mode. A single suction centrifugal fan  29  is mounted to one end of a rotary shaft  31  within a spiral casing  28  which is disposed in spaced juxtaposed relation to the indoor heat exchanger  30 . The rotary shaft  31  is supported on bearings mounted in the interface unit  24  and extends into the exterior unit  41  where it is connected to the electric fan motor  36  rotary shaft  35  by a belt and pulley assembly in this embodiment of the invention. The belt and pulley assembly, shown in FIG.  3  and FIG. 3 a  and in greater detail in FIG. 4, consists of a pulley  33  attached to the rotary shaft  31 , a pulley  34  attached to the fan electric motor rotary shaft  35 , an adjustable tension pulley  32  attached to the back of the motor casing  45  using pivot arm  45   a,  and a fan belt  44  which engages the respective pulleys  32 ,  33 ,  34 . Other suitable means for engaging the electric fan motor shaft  35  to rotary shaft  31 , such as a gear-based system, can be used. 
     The electric fan motor  36  is mounted to the exterior unit vertical partition plate  46  and base plate  47 . An axial propeller fan  37  is attached to the end of the electric fan motor rotary shaft  35 . The compressor  39  is mounted on the exterior unit base plate  47 . Compressor  39 , interior heat exchanger  30  and exterior heat exchanger  38  are interconnected using tubing  22  mounted within interior unit  21  and exterior unit  41 , and tubing segments  48  mounted within interface unit  24 . 
     In the above-described air conditioner, actuation of compressor  39  causes the refrigerant compressed in compressor  39  to be supplied to exterior heat exchanger  38 . Meanwhile, actuation of fan motor  36  causes axial propeller fan  37  to rotate, thereby resulting in a negative pressure prevailing in casing  40  so that fresh air is drawn by suction through suction opening  49  in exterior unit cabinet  43 , and is caused to pass through exterior heat exchanger  38  (see stream of air A). Thus, the refrigerant which was heated by being compressed in compressor  39  is cooled and condensed in exterior heat exchanger  38 . The refrigerant, which is transferred from exterior heat exchanger  38  to interior heat exchanger  30 , is expanded, thereby cooling interior heat exchanger  30 . Meanwhile, rotation of the fan motor  36  causes single suction centrifugal fan  29  to rotate, thereby causing a subatmospheric pressure to prevail in spiral casing  28 , so that indoor air is drawn by suction through suction opening  50  and is caused to pass through interior heat exchanger  30  (see stream of air B). At this time, the air drawn by suction is cooled by being brought into contact with the cooled interior heat exchanger  30 , and the cooled air is exhausted into the room again through outlet port  51  of spiral casing  28  by means of single suction centrifugal fan  29 . 
     FIG. 5 is a cross sectional detailed schematic diagram of interface unit  24  provided in FIG.  3  and FIG. 3 a.  FIG. 5 a  is an isometric view of the same interface unit. The interface unit casing  58 A is composed of an outer pipe section  58  threaded on its inner surface and an inner pipe section  59  threaded on its outer surface having appropriate diameters so as to mate with each other and to provide space to house the necessary components. The outer pipe section  58  is assembled onto inner pipe section  59  by engaging the screw threads. Thus, the length of the resulting two piece pipe assembly, which comprises the casing  58 A of interface unit  24 , is adjustable to permit installation of the interface unit  24  casing  58 A in exterior building walls of various thicknesses. The interface unit casing  58 A is secured to the rear panel of the interior unit cabinet  42  using fastening plate  63 A and bolts  63 , and to the exterior building wall surface using threaded fastening plate  62 . The interface unit casing  58 A is secured to the rear panel of the exterior unit cabinet  43  using bolts  63 B. 
     The rotary shaft  31  is mounted in the bearing housing tube  52  which is secured to the inner surface of interface unit  24  by two Allen screws  55 , and rotates when engaged by fan motor  36  while supported by bearings  53 , inserted at each end of bearing housing  52 . Connection of interior unit heat exchanger  30  and exterior unit heat exchanger  38  is effected by refrigerant tubes  56  fitted with suitable tubing connections at each end. Electrical signals and power are transferred from interior unit  21  to exterior unit  41  through electrical cable  57 . 
     A channel  66  for conveying fresh air from exterior unit  41  to interior unit  21  for injection of fresh air into the conditioned air stream is disposed between bearing casing  52  and electrical cables  57  and refrigeration tubing  56 . 
     A grooved or other suitable type flexible rubber sleeve  64  and rubber rings  64 A or, alternatively or in addition, rubber O-rings are installed over inner pipe section  59  of interface unit  24  to absorb mechanical vibrations, thereby minimizing the conduction of vibrations from interface unit  24  to building wall  27 . 
     FIG. 6 is a sectional view of the interface unit taken along the line I—I of FIG.  5 . In this figure, electrical cable bundle  57  is shown disposed near the top of interface unit  24  alongside two refrigeration tubes  56 , each wrapped with a layer of thermal insulation  65 . Below the aforementioned cable bundle  57 , refrigeration tubes  56  and insulation  65  is a channel  66  for conveying fresh air from the outdoor unit to the indoor unit. An adjustable damper  68  shown in the present figure in the fully open position, mounted in the center of channel  66 , is used to manually adjust the available cross sectional area of the channel  66 , thereby regulating the flow of air within channel  66 . The damper is fitted with a layer of thermal insulation on the interior room side to prevent thermal energy losses when closed. Use of the channel and damper for injection of fresh air is recommended for use with the compact indoor unit option shown in FIG.  7  and FIG. 7 a.  Adjustment of the relative opening position of damper  68  is effected by manipulation of a cable or handle (not shown) attached to damper  68  and accessible external to the indoor unit. Mounted below channel  66  is rotary drive shaft  31 , which rotates while supported by bearings  53  mounted within bearing housing  52 , the bearing housing  52  being mounted within interface unit  24  using set screws  55 . Channel  66  is anchored to bearing housing  52  using set screws  67 . Tubes  69  for conveying condensate water are at the sides of bearing housing  52  near the bottom of interface unit  24 , and are wrapped with a layer of thermal insulation  70 . 
     FIG. 7 is a sectional side view of a room air conditioner according to one embodiment of the invention, in which the interior unit  21  of the room air conditioner is disposed in a compact configuration and includes an absorbent pad for humidifying the conditioned air. FIG. 7 a  is an isometric view of this embodiment of the invention. This embodiment, includes a heat exchanger  71 , an indoor condensed water collection pan  75 , condensate removal tube  80  and water condensate feed tube  81 . A single suction centrifugal fan  73  is attached to one end of a rotary shaft  82  within a spiral casing  72 , which is disposed in spaced juxtaposed relation to indoor heat exchanger  71 . Rotary shaft  31  penetrates interface unit  24 , which is mounted within exterior wall  27 . Rotary shaft  31  extends into exterior unit  41 , where it is connected to and engaged by the electric fan motor rotary shaft (not shown). This connection is accomplished, in one embodiment of the invention, using a belt and pulley assembly (not shown), or in another embodiment of the invention, using a gear system (not shown). An absorbent pad  76  is disposed in juxtaposed position to indoor heat exchanger  71 . When the air conditioner is operating in the heating mode, condensate water collected in collection pan  85  under outdoor heat exchanger  84  is pumped to absorbent pad  76  by reversible pump  83 , saturating absorbent pad  76  with water. This results in humidification of the heated air stream prior to its conveyance to the room for the purpose of increasing the humidity content of the air to the desired level. In one embodiment of the invention, fresh air is drawn by suction from air inlet ports  88  of exterior unit  41  to the centrifugal fan  73  through fresh air duct  77  disposed in interface unit  24 , where the fresh air stream blends with air stream A conveyed through indoor heat exchanger  71 . 
     In one embodiment of the invention, in the cooling mode, reversible pump  83  conveys condensate water from indoor water collection pan  75  through tubes  80  and  86  to the top surface of outdoor heat exchanger  84 , resulting in the cooling of outdoor heat exchanger  84 . Excess condensate water is collected in outdoor unit collection pan  85  and discarded by draining through drain tube  89   a.    
     FIG. 8 is a schematic diagram of another preferred embodiment of the invention in which cooled air is conveyed from interior unit  91  to the interior of a first room  96  as well as to a second room  95 . Duct  90  leading to second room  95  is connected to branched air outlet plenum  94 , which is attached to the fan scroll casing  93  of interior unit  91 . This permits conveying conditioned air by centrifugal fan  92  to first room  96  through duct  90 A and/or second room  95  through duct  90 . Adjustable damper  89  is mounted at the junction point of branched air outlet plenum  94  and inlet port  97  of duct  90 . Adjustable damper  89  permits accurate regulation and distribution of the conditioned air flow rates conveyed to each room, and permits directing the air flow to only one of the rooms, if desired. 
     In the above embodiments of the invention, installation of the unit is limited to external building walls in which access to the room air conditioner is provided in the form of an appropriately-sized window or other suitable opening, to permit installation and service operations to be performed on the unit. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.