US 3682240 A
A crane having an overhead operator's cab and an air conditioning system for the cab. The air conditioning system includes a heat exchanger unit in the cab, a heat transfer system supplying heat transfer fluid to the heat exchanger unit for heating or cooling the cab air and apparatus for heating or cooling the heat transfer fluid.
Description (OCR text may contain errors)
United States Patent Cira v 14 1 Aug. 8, 1972 1541 AIR CONDITIONING SYSTEM FOR A CRANE CAB 72 Inventor: James w, Cira, 3047' East Derbyshire, Cleveland Heights, Ohio 44118  Filed: June 15, 1970  Appl. No.: 46,214
1  US. Cl. ..l65/42,' 165/61, 165/107,
. 162/259  Int. Cl. ..Bh 3/00  Field of Search ..l/l8, 29, 42, 61, 62, 64, 165/107, 26, 27,41; 62/201, 185, 259
 References Cited UNITED STATES PATENTS 1,896,953 2/1933 l-lassell ..165/26 2,000,467 5/1935 Lindseth ..l65/26 ,153,696 4/1939 Philipp ..62/l' 2,224,629 12/1940 BOfSe ..62/201 2,248,959 7/1941 Christi-nan ..62/259 2,513,517 ,7/1950 Reilly ..'.62/2S9 2,751,152
6/ 956 Ellenberger /26 Primary Examiner william J. Wye Attorney-'Watts, Hoffman, Fisher & Heinke ABSTRACT A crane having an overhead operators cab and an air conditioning system for the cab. The air conditioning system includes a heat exchanger unit in the cab, a heat transfer system supplying heat transfer fluid to the heat exchanger unit for heating or cooling the cab air and apparatus for heating or cooling the heat transfer fluid.
The cooling apparatus comprises a refrigeration unit having a heat rejecting heat exchanger supported remote from the cab, and a heat absorbing heat exchanger for cooling the fluid. A heating unit heats the fluid so that the cab air can be heated or cooled.
' 4 Claim, 2 Drawing Figures minnows a ma INVENTOR. JAMEE W. 6/84 I B m, 9M MA ATTOEA/E 7 5,
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cranes and more particularly relates to an air conditioning system for elevated crane cabs.
2. The Prior Art Movable cranes of the type used in factories, such as steel mills, etc. generally have a crane operators cab 1 which is elevated a substantial distance from the floor. The crane operator must have substantially un-' restricted visibility of areas in the buildings at least adjacent the crane. Consequently, operators cabs normally have walls formed largely by glass windows or windows of equivalent transparent material. When i such cranes are used in steel mills, buildings housing soaking pits, etc., the operators cab of the crane is sub-- ject to rather intense radiant-heat energy. When exposed to such radiation, the interior of the cab is heated by direct radiation as well as by the greenhouse effect created by the cab windows. The interior of crane cabs can thus frequently represent extremely large cooling loads.
In addition to undesirable heat, the atmosphere surrounding the crane and cab frequently carries fumes, smoke, etc. which can constitute, at least, irritants to the crane operator exposed to them.
Because the aforementioned conditions constituted operator. Furthermore, such ventilating systems didnot isolate the operator from the fumes or gases sometimes present about the crane.
The prior art has also proposed mechanical refrigeration units for maintaining the crane cab air temperatures at reasonable comfort levels and to enable recirculation of the crane cab air to reduce the quantity of fumes and gases entering the cab. These refrigeration units were supported on or adjacent the crane cabs with air cooling heat exchangers of the units locatedin heat exchange relationship with air circulating in the crane cab.
Because of their locations, these mechanical refrigeration units were difficult to install and service. Moreover, the high temperature ambient air at the units, and the radiant heat transferred to the units from various locations within the building, impaired the ability of these units to reject heat thereby reducing their effectiveness.
Prior art crane cab air cooling units usually included a compressor-condenser-evaporator refrigeration unit. The evaporator coil was located inside the crane cab. A suitable blower fan directed air across the evaporator coil so that the cab air was cooled. The condenser and compressor were located on a platform outside the cab. The evaporator coils were generally connected to the compressor and condenser by flexible high pressure refrigerant hoses extending through the cab wall.
Because of the relatively high ambient temperatures encountered by these refrigeration units, low efficiency refrigerants were used. These refrigerants were particularly adapted to function at high ambient temperatures. However, the low efiiciency of these refrigerants required relatively large compressors and condensers to produce a given cooling effect.
Even though low efficiency refrigerants were used with oversized condensers, the combination of high ambient air temperatures and radiant heat transfer to the condensers frequently caused these refrigeration units to short cycle due to excessive condenser pressure. This usually resulted from the compressor being stopped by high pressure cut-out controls associated with the condenser. Rapid increases of the cab air temperature to unduly high levels often resulted.
It was also difficult to modulate the crane cab air temperatures using these types of refrigeration systems. The problems of temperature control arose because the crane cabs contained a relatively small volume of air yet the cooling load on the cabs was great. Where operation of these systems was thermostatically controlled, 'the refrigeration system was often cycled with great frequency which is undesirable. If the refrigeration systems were continuously operated, the cab temperature was often reduced excessively, particularly when the cooling load in the cab was not large.
Hence, although crane cab cooling by the use of mechanical refrigeration units is a widespread practice, the performance of these cooling units has not been satisfactory. Furthermore, the units have been expensive, difficult to install and service and inefficient.
Cranes of the type referred to may be installed in unheated buildings. When the air temperature in such a building is low, the crane cab temperature may become uncomfortably cold. The prior art has not proposed apparatus for heating the cabs which utilizes at least portions of the existing cooling system, e.g., the fan coil unit in the cab.
Heat pump type refrigeration units constructed to both heat and cool air spaces by the use of refrigerant reversing valves are known; however, the use of such refrigeration units in connection with crane cabs has been prevented by the adverse conditions under which these units must operate. Since heat pump systems for use with crane cabs have not been practicable, effective. combined heating and cooling systems have not been available for conditioning air in crane cabs.
SUMMARY OF THE INVENTION The present invention provides an air conditioning system for a crane cab which is capable of both cooling and heating the crane cab, is readily installed and serviced, minimizes operator exposure to fumes, etc., in the cab, and in which the adverse effects of radiant heat transfer from within a building surrounding the crane to parts of the cooling unit are minimized.
The new air conditioning system includes an air handling, or fan coil, unit in the crane cab, a heat transfer system for supplying a heat transfer fluid to the air handling unit, refrigeration apparatus for cooling the fluid and a heater for heating the fluid. The air handling unit includes a heat exchanger coil through which the fluid circulates, and a blower for directing cab air across the coil.
The heat transfer system which supplies the heat transfer fluid to the heat exchanger includes a tank in which the fluid is heated or cooled, a circulating pump for the fluid, and suitable flexible hoses for directing the fluid to and from the heat exchanger coil. The fluid tlOn.
is preferably a liquidhaving a relatively large heat 2 tion systemJLocation of the housing on the crane bridge simplifies installation and servicing of the components in the housing. In the preferred construction the evaporator of the refrigeration unit is submerged in the water in the tank for cooling the water. An electrically energized heater unit is alsosubmerged in the tank so that the water in the tank'is heated. The volume of water in the heat transfer system is sufficiently large that even if the refrigeration system is stopped because .of high refrigerant pressure in the condenser, the thermal inertia of the water mill will continue to have a cooling ef-- fect in the crane cab after the system stops. This minimizes discomfort to the operator which would otherwise occur soon after the refrigeration system is cut off.
In a preferred construction, the air temperature in the crane cab is controlled by a bypass valve associated with the air handling unit. This valve, modulates the flow of the water through the air handling unit thereby controlling the amount of heat transferred between the crane cab air and the fan coil unit. Operation of the bypass valve is controlled by a suitable thermostat located in the crane cab.
, A principal object of the present invention is the provision of a new and improved air conditioning system for a crane cab which is capable of both heating and cooling air in the crane cab and is readily installed t and serviced.
above thefloor of the building. The operators cab may be of any operators construction and accordingly is not illustrated in detail. The crane further includes an air conditioning system generally shown by the unit located in the cab. The fan coil unit 20 transfers heat to or from air circulating in the cab. The unit 20 (FIG. 2) includes a housing 22 attached to the cab wall. A tube type heat exchanger coil 24 and a positive draft blower 26 are supported in the housing 22. The housing is provided with an air inlet 28 and an exhaust grill 29. Air in the cab is drawn into the inlet 28 by the blower, forced across the heat exchanger 24 and exhausted into the cab through the grill 29.
Cab airv passing across the heat exchanger 24 is heated or cooled by a heat transfer fluid circulating through the heat exchanger coil 24. This fluid is preferably a liquid having a relatively large heat capacity such as water. The water circulates through a heat transfer system generally designated at 30. The system 30 includes a water reservoir tank 32, acirculating pump 34, a water supply line 36 extending from the pump 34 to the heat exchanger 24 and a return line 38 which extends from the heat exchanger 24 to the tank 32. The water is either heated or cooled in the tank 32 I bypass conduit 42. The valve is preferablya solenoid operated valve which controls the flow of water' to the heat exchanger 24-to thus control the amount of Other objects and advantages of the invention will become apparent from consideration of the following detailed description made with reference to the accompanying drawings BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective 'view' of a portion of acrane embodying the present invention; and, v
FIG. 2 is a schematic illustration of a portion of the apparatus as shown in FIG. 1 with parts shown in cross section.
' onrA-ttaonascmwlolv OF A PREFERRED EMBODIMENT is supported beneath the bridge at a location elevated which form a partof the specificaheattransfer occurring between the air in the crane cab and the fan coil unit. A thermostat 44of suitable construction is located in the crane cab and controls the operation of the three-way valve 40.
When heating or cooling of the crane cab is required, the thermostat 44 operates the valve 40 to direct heated or cooled water' through the fan coil unit 20 from the supply line 36 to the return line 38. When the thermostat 44 is satisfied, the valve 40 is operated to its position for bypassing the heated or cooled water around the fan coil unit 20 from the line 36 through the When the switch 54 is closed, the heating element 50 is energized to heat the water in the tank 52.
The water in the tank 32 is chilled by an evaporator coil 56 of a condenser-compressor-evaporator type refrigeration system 60. The system 60 includes a ,compressor 62 driven by an electric motor 64. A condensor coil 66 is connected to the high pressure side of the compressor by a pipe 68. Refrigerant which has flowed through the condensor 66 communicates with a receiver 70 and an expansion valve 72 by way of a conduit 74. The expansion valve 72 is located adjacent the evaporator 56. The evaporator communicates with the lines 36, 38 are connected between the cab and the housing 80. The lines 36, 38 are preferably hoses which may be of any conventional flexible type and because static switch may of any conventional construction preferred construction an insulating blanket 78 surrounds the tank 32. The insulation minimizes heat gains or losses to or from the water. i
The housing 80 also supports a condensor cooling fan 86 driven by an electric motor 88. The fan 86 is located in a top exhaust opening of the housing and is fixed to a propeller shaft 90 which is supported in the housing by hearing 92. The shaft 90 is driven from the motor 88 by a belt transmission. Operation of the fan 86 creates a negative draft across the condenser through a side air inlet opening 94 in the housing. The condenser coil is located inside the housing adjacent the inlet 94 where it is shielded from radiant heat transfer yet exposed to the flow of cooling air induced through the inlet 94.
As is illustrated in FIG. 2, the water circulating pump is also driven from the motor 88 by a belt transmission. The motor 88 preferably operates continuously so that the water pump circulates water from the tank through the fan coil unit whether or not the compressor 62 is operating.
The housing 80 is preferably installed atop the crane bridge remote from the cab. This location provides ready accessibility for installation of the air tempering system as well as for servicing. Further, the housing is substantially shielded from radiant heat emitted below the crane bridge. This thermal shielding combined with the shielding provided the condenser coil by the housing itself minimizes the effects of radiant heat transfer to the condenser coil. This optimizes the effectiveness of the refrigeration system.
When air temperatures ambient the housing 80 become excessively high, the refrigerant pressure in the condenser coil may increase sufficiently to cause the refrigeration system to cut out or short cycle. This can occur even though the condenser coil is completely shielded from radiant heat transfer. When the compressor cuts out, the water continues to circulate from the tank to the fan coil unit in the crane cab. The volume of the tank 32 and mass of the water is sufficiently great that the crane continues to be cooled by the water for a considerable period after the refrigeration unit has ceased to operate. This avoids rapid temperature rises in the crane cab which would otherwise cause discomfort to the operator.
Because the heating and cooling systems are located in a self-contained unit installation of the air tempering system in an existing crane is relatively simple. The housing 80 is attached to the crane bridge, the fan coil unit 20 and its controls are installed in the cab and the of the system construction need not be constructed to withstand large internal pressures.
It can now be seen that anew and improved apparatus has been provided and that the objects heretofore enumerated and others have been accomplished.
While a preferred embodiment of the invention has been illustrated and described in detail, the invention is not tobe considered limited to the precise construction shown.
What is claimed is: I
1. In a crane installation operable for substantial periods in ahigh temperature environment comprising: a. an elevated support bridge disposed above a high temperature source of radiant heat; b. a crane operators cab depending from said supp g c. an air conditioning system for said crane cab; d. said air conditioning system comprising:
1. an air to liquid heat exchanger unit in said cab for conditioning air in said cab;
' 2. a refrigeration unit; and,
3. a heat transfer system for circulating liquid having a relatively high heat capacity between said refrigeration unit and said air to liquid heat exchanger unit whereby heat is transferred from the crane cab air to the refrigeration unit by said liquid;
. said refrigeration unit comprising:
1. a heat absorbing heat exchanger in heat transfer I relationship with liquid in said heat transfer system; and,
2. a heat rejecting heat exchanger for transferring heat to ambient atmosphere;
f. said refrigeration unit mounted on said support bridge remote from said crane cab and said heat rejecting heat exchanger located with respect to said support bridge so that said support bridge is at least partially interposed between said heat rejecting heat exchanger and high temperature sources below said support bridge to minimize radiant heat transfer from high temperature sources to the heat rejecting heat exchanger.
2. A crane installation as claimed in claim 1 wherein said heat transfer system comprises a reservoir containing a quantity of said liquid which is cooled by said heat absorbing heat exchanger, said reservoir supported by said support bridge and located remote from said crane cab, first conduit means extending from said reservoir to said crane cab for supplying liquid to said heat exchanger unit in said crane cab, second conduit means through which fluid flows from said crane cab heat exchanger unit, and pump means for circulating heat transfer liquid through said conduit means.
3. A crane installation as claimed in claim 2 wherein said reservoir comprises a tank and said heat absorbing heat exchanger comprises cooling coils disposed in said tank in heat transfer relationship with said liquid, said second conduit opening into said tank.
4. A crane installation as claimed in claim 2 further including heating means in said reservoir operative to transfer heat to said heat transfer liquid whereby air in said crane cab can be heated by said liquid.