CA1264944A - Roof-mounted air conditioner system having modular evaporator and condensor units - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A roof-mounted, modular system of evaporator and condensor units is constructed and designed to be interchangeable with existing condensor and evaporator units on a motorized vehicle, such as, a bus or rail car and can be mounted as a external single system or indepen-dently mounted and retrofit for incorporation ino the existing air conditioning and circulating system of the vehicle. The evaporator unit is compact and of low design height and is operable in combination with existing conden-sor units and compressor systems of the vehicle or can be combined with the modular condensor unit. The evaporator contains evaporator coils flanked on either side by heater coils, an expansion valve and control panel as well as the necessary blower fans together with a damper-controlled fresh air/return air system to meet all heating and cooling requirements of the vehicle.

Description

~` i4944 This application is a divisional of Canadian Serial No. 470,468, filed 19 Decembe~r, 1984. The invention relates to a no~e1 and improved air conditioning system for motor vehicles, such as, busses or rail cars.
In motor vehicle air conditioning systems there are numerous reasons for positioning both the condensor and evaporator coils in a common housing, principal among them being the necessity of direct connection of the r~friger~nt lines from the condensor coils via an expansion valve into the evaporator coils for most efficient operation.
Nevertheless, there are importan~ factors in favor of inde-pendently housing and mounting the evaporator and condensor units so as to be readily conformable for use on different types and styles of busses and other motor vehicles.
Moreover, modular construction and design o the condensor and evaporator units into separate housings achieves other beneficial results from the standpoint of replacement for existing evaporator and condensor units which are built into the motor vehicle so as not to necessitate removal of the existing units.
It is therefore an object of the present invention to provide for a novel and improved air conditioning system for motor vehicles which is extremely versatile and effi-cient in design and construction.
It is another object of the present invention to provide for a novel and improved air conditioner system comprised of modular condensor and evaporator units which can be mounted independently or together externally of or integrated into the roof of a motor vehicle.
A further object of the present invention is to provida for roof-mounted modular evaporator and condensor units which are so constructed and arranged as to be interchangeable with different sizes and types of condensor and evaporator units and which can be mounted ei~her as a single syste~ externally oE the rooE of a bus or other vehicle; or, if desired, can be independently mounted and effectively retrofit externally of the motor vehicle so as to be incorporated into the existing air conditioning and air circulating system of the vehicle without reconstructing or disturbing the existing system.
It is a further object of the present invention to provide for a novel and improved air conditioning system for motor vehicles with an evaporator unit adapted to be mounted on the roof of the vehicle and which is capable of supplying all of the heating and cooling requirements of the vehicle in an extremely efficient and reliable manner.
Yet an additional object of the present invention is to provide in an air conditioner system for busses for roof-mounted, modular condensor and evaporator units which can be externally mounted independently or together and effectively incorporated into the existing air circulating and engine coolant system of the bus so as to meet all heating and cooling requirements of the bus.
An air conditioner syste~ is adapted for mounting on the roof of a bus has an upper relatively flat roof, a ceiling spaced beneath the roof with a return air inlet disposed in the roof intermediately between air circulating ducts. The ducts extend between ~he roof and ceiling for directing conditioned air into the interior of the bus and a compressor draws refrigerant from evapora~or coils to discharge the refrigerant under pressure to a condensor unit. The condensor unit includes condensor coils for receiving refrigerant under pressure from the compressor 49~

and an air circulator for directing air across the conden-sor coils. An evaporator unit has an outer shallow, generally rectangul~r housing including a base panel con-forming to the contour of the roof. The base panel is attached ~o the roof so that the return air inlet and air circulating ducts are in communicatiorl with the interior of the evaporator housing. The evaporator coils are mounted on opposite sides of the return air inlet and heater coils extend horizontally in side-by-side relation to each oE the evaporator coils on opposite sides of the return air inlet.
A fresh air inlet is positioned in the evaporator housing, the evaporator housing having an evaporator air blower for inducing air through the return air inlet and fresh air inlet across the evaporator coils and heater coils for discharge through the air circulating ducts into the interior of the bus. Refrigerant lines extend between the condensor unit and the evaporator unit.
In accordance with the present invention, the roof-mounted, modular system of evaporator and condensor units are so constructed and designed as to be interchangeable with existing condensor and evaporator units on a motor vehicle, such as, a bus and which can be mounted either as a single syst~m externally of the bus or independently mounted and effectively retroEit so as to be incorporated into the existing air conditioning and air circulating system of the bus without disturbing its existing design and construction. For example, the conden-sor unit can be mounted wholly on the exterior of the bus and connected into the existing compressor and evaporator system; or it can be employed in combination with the modu-lar evaporator unit of the present invention and moun~ed either as a single system with the evaporator unit or separately mounted at differen~ loca~ions on the roof of the bus. Similarly, the modular evaporator unit of the present invention can be mounted externally of the roof with slots or openings formed throuyh the roof whereby to enable communication with the existing air circulating duct work. The evaporator unlt is extremely compact and of a low profile or design height, and is operable in com-bination wi~h existing condensor units and compressor systems of a bus or, as stated can be combined with the modular condensor unit of the present invention. The eva-porator system is further characterized by containing eva-porator coils flanked on either side by heater coils, an expansion valve and control panel together with the necessary blower fans to meet all heating and cooling requirements. In this relation, in the cooling mode, the blower fans are capable of drawing air both from the bus interior and from a fresh air intake at a predetermined ratio so as to effect the necessary cooling and drying of all refrigerated air entering the bus. Any condensation which accumulates on the evaporator coils is effeciently drained away through drain lines at each end of ~he coils.
In the heating mode, the same blower fans are activated such that the heat from the heater coils is intermixed with a predetermined ratio of return air to fresh air and discharged through the existing air circulating ducts of the bus. Preferably, the engine coolant in ~he bus is used as the heating medium through the coils and which upon passing through the coils is returned to the bus engine for reheating.

~2æ4s44 Broadly stated, the present invention provides in an air conditioner system adapted for rnoun-ting on the roof of a bus wherein said bus has an upper re:Latively flat roof, a ceiling spaced beneath said roof with a return air inlet dis-posed in said roof intermediately between air circulating ducts which extend between said roof and ceiling for directing con-ditioned air into the interior of said bus, there being compressor means to draw refrigerant from evaporator coils and to discharge said refrigerant unaer pressure, the improvement comprising: a modular condensor unit having a first shallow, generally rectangular housing including a base panel, mutually opposed sidewalls and end walls and a cover, elongated condensor coils extending horizontally within said housing and air circulating means for directing air across said condensor coils between said condensor coils and discharging through an air out-let in said cover; a modular evaporator unit having a second outer shallow, generally rectangular housing including a base panel, mutually opposed sidewalls and end walls and a cover, means for attaching said base panel to said roof whereby said return air inlet and said air circulating ducts are in communi-cation with the interior of said evaporator housing, said evaporator coils mounted on opposite sides of said return air inlet, and elongated heater coils between each of said evapora-tor coils and opposite sidewalls of said housing, a fresh air inlet in one said end wall of said evaporator housing, and evaporator air blower means in said evaporator housing for directing air through said return air inlet and fresh air inlet simultaneously across said evaporator coils and heater coils preliminary to discharge through said air circulating ducts into the interior of said bus; and refrigerant lines extending between said condensor unit and said evaporator unit.

Other ob-jects~ advan~ages and features of the pre-sent invention will become more readily appreciated and understood when taken together with the following detailed description ir~ csnjunction with the accompanying drawings, in which:
Figure 1 is a rear somewhat perspective view of a preferred form of air conditioning system schematically illustrating the refrigerant lines between the condensor, evaporator and compressor in the system in accordance with the present invention;
Figure 2 is a flow diagram of the refrigerant cir-cuit used in the preferred form of invention illustrated in Figures 1 to 7;
Figure 3 is a top plan view of the evaporator and condensor units shown in Figure 2 with portions of the covers removed;
Figure 4 is a side view in elevation of the con-densor and evaporator units shown in Figure 3;
Figure 5 is a front view of the condensor unit shown in Figures 3 and 4;
Figure 6 is a rear view of the evaporator unit as shown in Figures 3 and 4; and Figure 7 is a cross-sectional view of the pre-ferred form of evaporator unit in assembled relation to the roof and ceiling portions of a bus.
Referring in more detail to the drawings, there is illustrated in Figure 1 the working components of the pre-ferred form of air conditioning system which is specifi-cally adaptable for mounting on the roof of a bus B. In the system hereinafter described, ~rco~ -~ill be referred to as the heat-carrying medium, although it will be evident r b~ k - 6 ~

~264g~

that other refrigerants may be employed. Broadly, the freon or other eefrigerant in its gaseous state is drawn from evaporator coils 10 through suction line 12 into compressor 14 which is driven ofE of the bus engine M in a conventional manner. ~uring compression, the cool freon gas undergoes both an increase in temperature and pressure to a degree dependent upon ambient or air temperature~ The heated, pressuri~ed gas is then discharged by the compressor through discharge line 16 into condensor coils 18~ As the ~as circulates internally through the coils, ambient or outside air is drawn through ~he coil fins by a combina~ion of centrally located condensor fans or blowers 20 and side air inlets 22, the latter being illustrated in Figures 3 and 4. The freon gas is thereby liquified as a result of the air movement decreasing the temperature in and around the condensor coils 18 and the increased pressure of the gas created by the compressor. The heat given up by the gas in its conversion into a liquid is expelled by the condensor fans 20.
From the condensor coils 18, the liquid refri-gerant is forced into a receiver-dryer 24 via the refri-gerant lines 23 from the condensor coils. The refrigerant then travels and advances into the evaporator section via liquid line 26 which is attached to the expansion valve 27, the latter controlling the amount of liquid freon entering the two evaporator coils 10 for proper coolant vapori2a-tion. The expansion valve 27 opens and closes in accor-dance with the temperature and pressure at the evaporator outlet so as to control the amount of freon entering the evaporator coils. Here, the freon enters the evaporator coils 10 through a series of distributor tubes 28 which insure that the ~reon is distribu~ed evenly within the coils. As best seen from Figure 1, t:he receiver-dryer 24 are positioned within the condensor section and together act as a cooling chamber for the hot liquid refrigerant as well as a mixing chamber for oil and refrigerant. In addi-tion, the refrigerant is stored at that point un~il needed by the evaporators while being filtered and any moisture being dried from the system. Because the expansion valve 27 permits but a selected amount of liquid freon into the evaporator coils, the internal pressure of the coils lQ is reduced causing the freon to absorb heat from the air passing over the evaporator coils as it is vaporized. In a manner to be described, this air is normally drawn from the bus interior through a return air grille 30 and from the exterior of the bus through the fresh air trellis 32 at the rear end of the evaporator section, as shown in Figure 3.
The net effect is to cool and dry all refrigerated air which enters the bus, and the condensation which accumula-tes on the evaporator coils 10 is drained away through drain lines, not shown, located at each end of the evapora-tor coils 10.
The air movement across the evaporator coils is initiated and controlled by evaporator blowers 34 located outboard of the evaporator coils and communicating in a manner hereinafter described with air circulating ducts which lead into the bus interior. In this way, heater coils 36 may be in~erposed between the evaporator coils and blowers 34 which heater coils 36 receive hot engine coolant from ~he engine when desired to increase the temperature in the interior of the bus, the engine coolant being delivered 126~

through circulating lines 37 and 38 to and from the heater coils 36.
Referring in more de~ail to Figures 3 to 7, an important feature of the present invention resides in the modular construction and arrangement of the evaporator and condensor units such that they can be roof-mounted on the bus either independently or together and be interchangeably used with existing condensor and evaporator units on the bus~ To this end, and as best seen from a consideration of Figures 3 to 7, inclusive, a shallow, generally rectangular housing 40 serves as an enclosu~e for the condensor coil 18 and intermediate fans or blowers 20. The housing 40 has a base panel 41 conforming to the contour of the roof sur-face, the base panel being elongated in the lengthwise direction of the bus and attachable to the roof by means of suitable fasteners as represented at 42 which extend through the base panel and roof at spaced intervals as illustrated in Figure 3. Opposite sidewalls 44 extend ver-tically upward from opposite sides of the base panel and contain the side air inlets 22. The sidewalls 44 are joined by a rear vertical wall 45 at one end and by a front sloped wall 46, the latter con~aining front air inlet grilles 48. The sidewalls 44, rear wall 45 and front wall 46 terminate in an upper peripheral edge 49 upon which is mounted a removable cover 50 which slopes or inclines laterally and downwardly away from a common center raised portion 52. In Figure 3, the cover 50 is broken away except for the center, raised portion 52 hereinafter described.
It will be noted that the condensor coils 18 con-sist of a series of transversely extending fins or pl~tes disposed in laterally spaced relation to one another on opposite sides of the blowers 20 and are directly affixed to the base panel 41 to extend lengthwise of the housing 40, the fins being of generally rectangular configuration with their longer side edges extending transversely of the length of the housing 40. The blowers 20 consist of a series of vertical access ~ans disposed in longitudinally spaced relation to one another, each being located beneath an opening 54 in the raised portion 52 and each having a motor drive mounted beneath fan blades 55 on the base panel 41. The side air inlets 22 in ~he sidewalls 44 of the con-densor section are normally closed by flaps in the manner described in the hereinbefore referred to Patent No.
4,201,064 so as to open automatically in the event that a negative pressure is produced in the condensor housing 40.
The raised portion 52 of the cover contains a grille 52' aligned in spaced relation above the blowers 20 so that air induced or drawn into the housing by the blowers 20 through the air inlet 22 and across the condensor coils 18 will be discharged upwardly through the openings 54. In this manner, the entire housing 38 and enclosed condensor coils and blower Eans are made to be of extremely low profile or design height and can be mounted externally of the bus without modifying the body or shell of the bus.
Somewhat different considerations are involved in the construction of the evaporator section and its mounting to the bus in that the evaporator section must communicate with the existing ductwork in the bus. Conventionally, the bus B has air inlet ducts 58 located on either side of the bus body directly beneath the roof R which slope laterally outwardly and downwardly into air distribution ducts 60 which communicate with air discharge nozzles 52 at longitu-dinally spaced intervals along the length o the bus B
directly above the side windows W shown in Figure 1. It is also necessary to make provision for a centrally located air inlet opening through the roof and ceiling of the bus in orde~ for return air to be drawn from the interior of the bus for flow across the evaporator coils 10 in the eva-porator section, this air inlet opening being designated at 64 in the ceiling portion C of the bus ~ody as shown in Figure 7~ In order to establish the necessary com-munication with the air inlet opening 64 and the air inlet ducts 58, the evaporator unit as illustrated in Figures 2 to 5 comprises a shallow generally rectangular housing 66 having a base panel 67 conforming to the contour of the roof R except for the provision of downwardly projecting chutes or ducts 68 on opposite sides of the base panel.
The ducts 68 are of generally triangular configuration and project into slots or openings formed in the roof of the bus, and openings 68' communicate with the air inlet ducts 58 beneath the existing roof line of the bus. The exten-sion ducts 68 are spaced as illustrated in Figure 4 to accommodate any structural supports in the hus and are located directly beneath the evaporator blowers 34 so as to permit the evaporator blowers to discharge the air drawn over the evaporator coils 10 downwardly through the air discharge nozzles 62. The remainder of the evaporator housing comprises opposite vertical sidewalls 70 extending upwardly from the base panel and joined at one end by a common vertical front wall 71 and at the rear end by a com-mon rear vertical wall 72. The sidewall 70, front and rearwalls 71 and 72, respectively, t~rminate in a common upper ~ 11 --~*~

peripheral edge 74 which is adapted to receive a cover 75 so as to ~ully enclose the component: par~s of the evapora-tor within the housing 66. The outside air inlet 32 in the rear wall 72 has a series of pivotal dampers 69 arranged thereacross and controlled to move be~ween an open and closed position to regulate the amount of fresh air drawn into the housiny 66.
The base panel 67 is affixed to the roof R in the same manner as described with respect to the base panel of the condensor unit; namely, by suitable fasteners 42 at spaced intervals around the outer portion of the ~ase panel and which extend both through the thickness of the base panel and roof to removably attach the evaporator unit in place.
The evaporator coils 10 are elongated in the lengthwise direc~ion of the housing and affixed to the base panel to extend lengthwise along opposite sides of the central air inlet grille 30 which is formed in the base panel to extend the greater length of the housing as shown in Figure 3, the air inlet grille 30 being aligned with the air inlet opening 64 in the ceiling C of the bus~ A filter 92 is disposed in the ceiling C across the opening 64, and a series of pivotal dampers 73 are disposed across the return air grille 30. The dampers are movable between an open and closed position to regulate the amount of return air drawn into the housing 65 by the blowers 3~.
Each of the evaporator coils 10 includes transver-sely extending rectangular fins 76, each having its longer dimension extending in a transverse direction and a shorter dimension extending vertically of the housing. The water heater coils 35 as earlier described are positioned between the evapora~or coils 10 and the blowers 34, each heater coil ~eing wrapped spirally around a center core, not shown, and ext2nding for a length corresponding to that of the evaporator coils 10 In turn, the evaporator blowers 34 are mounted outboard of the hot water heater coils 36 there being a series of four radial blowers at equally spaced intervals along the length of the housing directly outboard of the water heater coils and inboard of a sidewall 70.

The evaporator and condensor housings 66 and 40, respectively, are so constructed and arranged as to enable connection to the roof of the bus either independently or together. In order to facilitate interconnection between the units, the rear wall 45 and front wall 71 of the con-densor and evaporator units, respectively, are complemen-tary to one another and are correspondingly straight ~so as to permit flush mounting and attachment to one another by means of an adnesive or suitable fasteners, not shown, which may suitably take the form of lag bolts extending through aligned openings in the walls 45 and 71 at spaced intervals across the widths of the housings. Praferably, the housings are of lightweight fiberglass construction so as to be corrosion-resistant and extremely durable. A
gasket 82 is interposed between external surfaces of the walls 45 and 71 to insulate the housings from one another and to form a cushioned connection between the walls.
Referring to Figures 1 and 2, openings are formed in the mating walls 4~ and 71 for the extension of the refrigerant lines; namely, the discharge line 16 extending from the compressor to the condensor coils and the line 26 from the receiver-dryer 24 to the expansiorl valve 27~ It will be - 13 ~

94~L

evident that ~hen the condensor and evaporator housings are independently mounted on separate sections of the bus that the refrigeran~ lines may be increased in length and run through the same openings in the walls 45 and 71 to establish the necessary interconnection between the air conditioning components as described~
In operation, the necessary control for heating, ventilating and air conditioning may be combined into one central control unit in response to sensing out~ide and inside tempeeatures via an outer sensor or thermostat and an inside sensor or thermostat. The outer sensor is placed in the outside air inlet 32, and the inside sensor is posi-tioned at the return air grille 30. The outside sensor is operative to turn off the compressor 14 below a predeter-mined temperature level, such as, 50F. (plus 10C.), and to start the compressor when the temperature is above a predetermined level, such as, 55F. (13C.). In turn, the inside sensor is operative to regulate the heater coils and, for example, to control opening of a valve 37' in line 37 at temperatures below a predetermined level, such as, 72F. (20C.). Upon reaching a temperature level above 72F., the inside sensor will close the valve 37' to interrupt the heating cycle. The dampers are normally regulated by the inside sensor and outside sensor to pro-vide a ratio or mixture of 80% return air to 20~ fresh air.
At the same time, ~he dampers are regulated to establish optimum ratios of return air to outside air, depending upon the temperature level, so as to maximize the efficiency and performance of the compressor and heater units.
Specifically, the opening and closing movement of each damper unit is controlled by an air cylinder 90 which ~6~9~

receives air under pressure from a source of air applied over line 91 via the filter 92 in~o a solenoid valve 93.
The valve 93 opens in response to a signal from a control circuit 94 causing air to be directed into bo~h cylinders 90 whereby to simultaneously extend the rods of the cylin-ders and which through suitable linkage, not shown, will operate to pivot one damper unit to a closed position and the other damper unit to an open position. The signal from the control circuit 94 is genera~ed in response to the tem-perature level as sensed by the ou~side sensor 86. For example, at temperatures below 50F., the outside damper 69 is fully closed and the inside damper 73 i5 fully open. As the tempera~ure increases to above 60F., the outside dam-pers are gradually opened and the inside dampers are closed. When the temperature exceeds 65, ~he dampers are regulated to deliver 80~ return air to 20% fresh air.
Again, the ratio may be varied over a wide range by regula-tion of the dampers for the fresh air and return air inlets from one extreme in which the inlet 32 is fully closed and the system operated solely with return air, such as, for extremely high temperature levels in which it is desired to operate the co~pressor at full capacity and to cool only the return air from the interior of the bus; or to the other extreme when it is desired to operate solely on out-side air and to close the return air inlet. Preferably, when either damper is in the closed position it will nevertheless permit on the order o 20% of the total air to be drawn through that damper; or in other words to establish the 80%:20% ratio.

From ~he foregoing, it will be evident that the system of the present invention offers a great deal of ver-satility and interchangeability specifically wherein the ~6~

condensor and evaporator units are operative together or individually in combination with other systems and in a manner which will enable direct connection into existing systems on a bus without disturbing or modifying the bus design other than o make the necessary connections Eor the evaporator section into the existing air circulating systems. Th~ air conditioning system as described is further conformable for use with articulated busses as well as light rail systems wherein condensor and evaporato~
units may be mo~nted together on each section or a single condensor unit may be mounted on one roof section ~nd usable in combination with evaporator units placed on each roof section of the articulated system.
It is therefore to be understood that various modifications and chang~s may be made in the construction and arrangement of the preEerred form of the present inven-tion without departing from the spirit and scope thereof as defined by the appended claims.

~ 16 -

Claims (4)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In an air conditioner system adapted for mounting on the roof of a bus wherein said bus has an upper relati-vely flat roof, a ceiling spaced beneath said roof with a return air inlet disposed in said roof intermediately bet-ween air circulating ducts which extend between said roof and ceiling for directing conditioned air into the interior of said bus, there being compressor means to draw refri-gerant from evaporator coils and to discharge said refri-gerant under pressure, the improvement comprising:
a modular condensor unit having a first shallow, generally rectangular housing including a base panel, mutually opposed sidewalls and end walls and a cover, elongated condensor coils extending horizontally within said housing and air circulating means for directing air across said condensor coils between said condensor coils and discharging through an air outlet in said cover;
a modular evaporator unit having a second outer shallow, generally rectangular housing including a base panel, mutually opposed sidewalls and end walls and a cover, means for attaching said base panel to said roof whereby said return air inlet and said air circulating ducts are in communication with the interior of said eva-porator housing, said evaporator coils mounted on opposite sides of said return air inlet, and elongated heater coils between each of said evaporator coils and opposite sidewalls of said housing, a fresh air inlet in one said end wall of said evaporator housing, and evaporator air blower means in said evaporator housing for directing air through said return air inlet and fresh air inlet simulta-neously across said evaporator coils and heater coils pre-liminary to discharge through said air circulating ducts into the interior of said bus; and refrigerant lines extending between said con-densor unit and said evaporator unit.

2. In an air conditioner system according to claim 1, said condensor unit and said evaporator unit housings having complementary end walls, and means for releasably attaching said complementary sidewalls together, said con-densor unit having air inlets extending along said sidewalls and one of said end walls.

3. In an air conditioner system according to claim 2, said condensor unit and said evaporator unit being connected in tandem, said complementary end walls defining a rear wall of said condensor unit housing and a front wall of said evaporator unit housing, and a rear wall of said evaporator unit housing having said fresh air inlet centrally disposed therein.

4. In an air conditioner system according to claim 3, said evaporator coils being elongated and extending horizontally in a direction parallel to the length of said bus, said heater coils being elongated and extending hori-zontally in a direction parallel to the length of said bus intermediately between said evaporator coils and said air circulating ducts, said return air inlet and said fresh air inlet being located intermediately between said evaporator coils.