Air conditioning system with enhanced dehumidification feature

An air conditioning system comprising:

• a heat exchanger including a cooling medium path, through which a cooling medium is pumped, and a heat exchanger air path through which air is forced;
• a return duct extending to a source of air from an indoor space;
• a ventilation duct extending to a source of outdoor air;
• a supply duct through which air is discharged from said air conditioning system into said indoor space
• a first air path from said ventilation duct through said heat exchanger air path to said supply duct;
• a second air path from said return duct through a bypass duct to said supply duct;
• fan means for forcing air through said return, ventilation, and supply ducts, and through said first and second air paths;
• a first damper extending between said second air path and said first air path at a first air mixing location between said ventilation duct and said heat exchanger;
• a second damper extending across said second air path, to restrict airflow through said second air path while permitting airflow through said first damper;
• cooling regulation means controlling a rate at which heat is removed from air moving through said first air mixing location;
• and
• system control means for providing a variable overall rate of air cooling, said system control means varying operation of said cooling regulation means to provide relatively low levels of said overall rate of air cooling while holding said first damper closed and said second damper open, said system control means varying said first and second dampers to introduce a flow of air from said return duct into said air mixing location as required to provide relatively high levels of said overall rate of cooling.

Apparatus for controlling a rate at which a mixture of outdoor air from a ventilation duct and indoor air from a return duct is cooled by cooling means within an air conditioning system, and for enhancing the dehumidification of said outdoor air, said apparatus operating in response to signals from system control means indicating that an overall rate of cooling should be increased or decreased, said apparatus comprising:

• an input mixing plenum between said ventilation duct and said cooling means;
• a bypass duct extending around said cooling means from said return duct;
• a first damper extending between said return duct and said input mixing plenum;
• a second damper extending between said return duct and said bypass duct;
• fan means for forcing air through said cooling means and through said bypass duct;
• an output mixing plenum having a first input from said cooling means and a second input from said bypass duct;
• cooling regulation means for controlling a cooling rate at which cooling occurs within said cooling means, said cooling regulation means being driven in a first direction to increase said cooling rate as a signal of a first type from said system control means is applied to a cooling regulation motor, said cooling regulation means being driven opposite said first direction to decrease said cooling rate as a signal of a second type from said system control means is applied to said cooling regulation motor;
• return damper drive means for operating said first and second dampers, said return damper drive means being driven in a direction to open said first damper and to close said second damper as said signal of a first type is applied to a return damper motor, said return damper drive means being driven in a direction to close said first damper and to open said second damper as said signal of a second type is applied to said return damper motor;
• first switching means applying said signal of a first type to said return damper motor when said cooling regulation drive is in a position maximizing said cooling rate, said first switching means applying said signal of a first type to said cooling regulation motor when said cooling regulation drive is not in said position maximizing said cooling rate;
• and
• second switching means applying said signal of a second type to said cooling regulation motor when said return damper drive means is in a position fully closing said first damper, said second switching means applying said signal of a second type to said return damper motor when said return drive motor is not in said position fully closing said first damper.

Apparatus for controlling a rate at which a mixture of outdoor air from a ventilation duct and indoor air from a return duct is cooled by cooling means within an air conditioning system, and for enhancing the dehumidification of said outdoor air, said apparatus operating in response to a control signal from system control means indicating a level of an overall rate of cooling, said apparatus comprising:

• an input mixing plenum between said ventilation duct and said cooling means;
• a bypass duct extending around said cooling means from said return duct;
• a first damper extending between said return duct and said input mixing plenum;
• a second damper extending between said return duct and said bypass duct;
• fan means for forcing air through said cooling means and through said bypass duct;
• an output mixing plenum having a first input from said cooling means and a second input from said bypass duct;
• cooling regulation means for controlling a cooling rate at which cooling occurs within said cooling means, said cooling regulation means operating to increase said cooling rate as said control signal increases in intensity within a first range, said cooling regulation means operating to decrease said cooling rate as said control signal decreases in intensity within said first range;
• return damper drive means for operating said first and second dampers, said return damper drive means being driven in a direction to open said first damper and to close said second damper as said control signal increases in intensity within a second range, said return damper drive means operating to close said first damper and to open said second damper as said control signal decreases intensity within said second range, said second range including higher levels of intensity of said control signal than said first range.