Mobile air conditioning system and control mechanisms therefor

Abstract

The performance of mobile air conditioning systems is improved with the use of a pressure sensing valve to control refrigerant flow in the system. The pressure sensing valve is connected between the condenser and the evaporator. The control valve senses the refrigerant pressure adjacent the evaporator, ie. the input, or output, or the combination of both, to control the refrigerant flow through the evaporator in a manner to improve the performance of the system. The reference pressure for the valve can be the atmosphere or a fixed or variable source. Various other operating variables can be sensed to control the variable source in a manner to interact with the sensed pressure to provide added control of system performance.

What is claimed:  
     
         1 . A pressure sensitive valve adapted to control the amount of refrigerant flow in vehicular air conditioning systems that include a compressor, a condenser, an evaporator and an accumulator interconnected for serial refrigerant flow therein, and wherein the vehicle engine drives the compressor so that the refrigerant pumping capacity of the compressor increases and decreases with increases and decreases in vehicle engine speed, and the heat rejection capacity of the condenser increases and decreases in air flow there through due to increases and decreases in the vehicle speed and engine fan speed, said valve comprising: 
 a casing for the valve including an input port adapted to be connected to receive refrigerant from the condenser, and an output port adapted to be connected to deliver the refrigerant to the evaporator;    a variable valve located within the casing between the inlet port and the output port for controlling the size of the opening between the ports;    a pressure sensing mechanism adapted to be connected for sensing refrigerant pressure adjacent the evaporator to provide a displacement motion that is a function of the magnitude of the sensed pressure, and    a coupling mechanism connected between the pressure sensing mechanism and the variable valve to control the size of the opening as a function of the magnitude of the sensed pressure, so that the variable valve is adapted to function as a variable orifice and interact with the accumulator to control the amount of refrigerant flow through the system so as to vary the cooling capacity of the system relative to changes in at least one of the compressor and condenser capacities.    
     
     
         2 . A refrigerant control system of    claim 1    wherein the accumulator accumulates liquid refrigerant from the evaporator and bleeds off accumulated liquid refrigerant keep the system charged.  
     
     
         3 . A pressure sensitive valve of    claim 1    wherein the valve opening increases to increase refrigerant flow with increases in compressor capacity and decreases to decrease refrigerant flow with decreases in compressor capacity.  
     
     
         4 . A pressure sensitive valve of    claim 3    wherein the valve opening increases to increase refrigerant flow with increases in condenser capacity and decreases to decrease refrigerant flow with decreases in condenser capacity.  
     
     
         5 . A pressure sensitive valve of    claim 1    wherein the range of operation of the variable valve is limited so that the opening does not close.  
     
     
         6 . A pressure sensitive valve of    claim 1    wherein the sensed pressure is adapted to be received from the pressure of the refrigerant adjacent the valve output port.  
     
     
         7 . A refrigerant control system of    claim 1    wherein the pressure sensitive mechanism is adapted to sense evaporator output refrigerant pressure.  
     
     
         8 . A pressure sensitive valve of    claim 7    wherein a second sensed refrigerant pressure is also adapted to be received and combined with refrigerant pressure from the output port to provide a combined sensed differential pressure.  
     
     
         9 . A pressure sensitive valve of    claim 1    wherein the valve is adapted to control the size of the valve opening in a direction toward evaporator refrigerant pressure at the output of the evaporator corresponding to saturated refrigerant vapor at substantially total vaporization adjacent the output of the evaporator and substantially total saturated liquid refrigerant at saturation temperature within the evaporator.  
     
     
         10 . A pressure sensitive valve of    claim 1    including a reference port adapted to provide a pressure reference source wherein the pressure sensing mechanism senses thl-pressure difference between the sensed pressure and the reference pressure to provide the displacement motion.  
     
     
         11 . A pressure sensitive valve of    claim 10    wherein the reference port is adapted to be exposed to the atmosphere as the reference pressure.  
     
     
         12 . In a vehicular air conditioning system including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein wherein the vehicle engine drives the compressor so that the compressor capacity is a function of engine speed, and the capacity of the condenser is a function the vehicle speed and engine fan speed, a control system for controlling refrigerant flow in the system comprising: 
 a pressure sensitive control valve having an input port, an output port, a variable valve mechanism there between having a variable opening for connecting the input port to the output port and a pressure sensing mechanism coupled to the variable valve mechanism for providing a displacement movement thereto for controlling the size of the opening of the valve mechanism;    means for coupling the input and output ports of the pressure sensitive valve in the air conditioning system at a point between the condenser and the evaporator, and means for coupling the pressure sensing mechanism to sense the refrigerant pressure adjacent to the evaporator so that the valve function as a variable orifice to control the amount of refrigerant flow through the system so as to vary the cooling capacity of the system relative to changes in at least one of the compressor and condenser capacities.    
     
     
         13 . A refrigerant control system of    claim 12    wherein the pressure sensitive mechanism senses evaporator input refrigerant pressure.  
     
     
         14 . A refrigerant control system of    claim 12    wherein the pressure sensitive mechanism senses evaporator output refrigerant pressure.  
     
     
         15 . A refrigerant control system of    claim 12    wherein the pressure sensitive mechanism senses both the input and output evaporator refrigerant pressure.  
     
     
         16 . A refrigerant control system of    claim 12    wherein the pressure sensitive mechanism includes a reference port for receiving a reference pressure for comparing the sensed pressure with the reference pressure and for providing the displacement motion as a function of the pressure difference there between.  
     
     
         17 . A refrigerant control system of    claim 16    wherein the reference pressure is the atmospheric pressure.  
     
     
         18 . A refrigerant control system of    claim 16    wherein the reference pressure source is adjustable and including means for sensing ambient temperature for adjusting the reference pressure source in a direction so that the differential pressure is in a direction to increase the size of the valve opening.  
     
     
         19 . A refrigerant control system of    claim 16    wherein the reference pressure source is adjustable and including means for sensing ambient humidity for adjusting the reference pressure source in a direction so that the differential pressure is in a direction to increase the size of the valve opening.  
     
     
         20 . A refrigerant control system of    claim 16    wherein the reference pressure source is adjustable and including means for sensing vehicle speed for adjusting the reference pressure source in a direction so that the differential pressure is in a direction to decrease the size of the valve opening.  
     
     
         21 . A refrigerant control system of    claim 16    wherein the reference pressure source is adjustable and including means for sensing engine speed for adjusting the reference pressure source in a direction so that the differential pressure is in a direction to decrease the size of the valve opening.  
     
     
         22 . A refrigerant control system of    claim 16    wherein the reference pressure source is adjustable and including means for sensing evaporator output temperature for adjusting the reference pressure source in a direction so that the differential pressure is in a direction to increase the size of the valve opening.  
     
     
         23 . A refrigerant control system of    claim 12    wherein an orifice is connected in parallel to the pressure sensitive valve.  
     
     
         24 . A refrigerant control system of    claim 12    wherein the accumulator accumulates liquid refrigerant from the evaporator and bleeds off accumulated liquid refrigerant to maintain the refrigerant charge of the system.  
     
     
         25 . A refrigerant control system    claim 12    wherein the valve controls the size of the valve opening in a direction toward evaporator refrigerant pressure at the output of the evaporator corresponding to saturated refrigerant vapor at substantially total vaporization adjacent the output of the evaporator and substantially total saturated liquid refrigerant at saturation temperature within the evaporator.  
     
     
         26 . In a mobile air conditioning system including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein, wherein the vehicle engine drives the compressor so that the compressor capacity is a function of engine speed, and the capacity of the condenser is a function the vehicle speed and engine fan speed, a control system for controlling the flow of refrigerant flow in the system comprising: 
 a control valve connected in the system between the condenser and the evaporator to control the refrigerant flow through the system, said control valve being responsive to input signals to vary the flow of refrigerant flow there through;    a sensor for detecting refrigerant pressure adjacent to the evaporator and at least one of a plurality of variables including ambient temperature, ambient humidity, engine speed, vehicle speed and evaporator output temperature, and    means for combining the output of the pressure sensor with at least the output of one of the plurality of variables as input signals to the control valve to control the refrigerant flow in the system with changes in at least one of the compress and condenser capacities. .    
     
     
         27 . A pressure sensitive valve adapted to control the amount of refrigerant flow in vehicle air conditioning systems that include a compressor, a condenser, an evaporator and an accumulator interconnected for serial refrigerant flow therein, and wherein the vehicle engine drives the compressor so that the refrigerant pumping capacity of the compressor increases and decreases with increases and decreases in vehicle engine speed, and the heat rejection capacity of the condenser increases and decreases with air flow there through with increases and decreases in vehicle speed and engine fan speed, said valve comprising: 
 a casing for the valve including an input port adapted to be connected to receive refrigerant from the condenser, and a output port adapted to be connected to deliver the refrigerant to the evaporator;    a variable valve located within the casing between the inlet port and the output port for controlling the size of the opening between the ports;    a pressure sensing mechanism adapted to be connected for sensing evaporator refrigerant pressure adjacent the evaporator to provide a displacement motion that is a function of the magnitude of the sensed pressure, and    a coupling mechanism adapted to be connected between the pressure sensing mechanism and the variable valve to control the size of the opening as a function of the magnitude of the sensed pressure in a direction towards evaporator refrigerant pressures adjacent the output of the evaporator corresponding to substantially total refrigerant vaporization so as to control the heat absorbing capacity of the evaporator relative to changes in at least one of the compressor and condenser capacities.    
     
     
         28 . A refrigerant control system of    claim 27    wherein the accumulator accumulates liquid from the substantially totally vaporized refrigerant outputted by the evaporator and bleeds off the accumulated liquid refrigerant to keep the system charged.  
     
     
         29 . A pressure sensitive valve of    claim 28    wherein the variable valve is responsive to the displacement action of the pressure sensitive mechanism to control the size of the valve opening in a direction toward evaporator refrigerant pressure corresponding to saturated refrigerant vapor at substantially total vaporization adjacent the output of the evaporator and substantially total saturated liquid refrigerant at saturation temperature within the evaporator.  
     
     
         30 . A pressure sensitive valve of    claim 27    wherein the size of the valve opening increases to increase refrigerant flow with increases in compressor capacity and decreases to decrease refrigerant flow with decreases in compressor capacity.  
     
     
         31 . A pressure sensitive valve of    claim 30    wherein the size of the valve opening increases to increase refrigerant flow with increases in condenser capacity and decreases to decrease refrigerant flow with decreases in condenser capacity.  
     
     
         32 . A pressure sensitive valve of    claim 27    wherein the pressure sensing mechanism measures pressure adjacent the input of the evaporator.  
     
     
         33 . In a vehicular air conditioning system including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein and wherein the vehicle engine drives the compressor so that the refrigerant ptunping capacity of the compressor increases and decreases with increases and decreases in vehicle engine speed, and the heat rejection capacity of the condenser increases and decreases with air flow there through with increases and decreases in vehicle speed and engine fan speed, a control system for controlling the flow of refrigerant flow in the system comprising: 
 a pressure sensitive control valve having an input port an output port, a variable valve mechanism there between having a variable opening for connecting the input port to the output port and a pressure sensing mechanism coupled to the variable valve mechanism for providing a displacement movement thereto for controlling the size of the opening of the valve mechanism;    means for coupling the input and output ports of the pressure sensitive valve in the air conditioning system at a point between the condenser and the evaporator, and means for coupling the pressure sensing mechanism to sense the refrigerant pressure adjacent to the evaporator to control the refrigerant flow through the valve mechanism as a function of the magnitude of the sensed pressure in a direction toward evaporator pressures adjacent the output of the evaporator corresponding to substantially total refrigerant vaporization so as to control the heat absorbing capacity of the evaporator relative to changes in at least one of the compressor and condenser capacities.    
     
     
         34 . A control system of    claim 33    wherein the accumulator accumulates liquid from the substantially totally vaporized refrigerant outputted by the evaporator and bleeds off the accumulated liquid refrigerant to keep the system charged.  
     
     
         35 . A control system of    claim 33    wherein the variable valve is responsive to the displacement action of the pressure sensitive mechanism to control the size of the valve opening in a direction towards evaporator refrigerant pressures corresponding to saturated refrigerant vapor at substantially total vaporization adjacent the output of the evaporator and substantially total saturated liquid refrigerant at saturation temperature within the evaporator.  
     
     
         36 . A control system of    claim 33    wherein the size of the valve opening increases to increase refrigerant flow with increases in compressor capacity and decreases to decrease refrigerant flow with decreases in compressor capacity.  
     
     
         37 . A control system of    claim 33    wherein the pressure sensing mechanism measures pressure adjacent the input of the evaporator.  
     
     
         38 . In a vehicular air conditioning system including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein and wherein the vehicle engine drives the compressor so that the refrigerant pumping capacity of the compressor increases and decreases with increases and decreases in vehicle speed, and the heat rejection capacity of the condenser increases and decreases with air flow there through with increases and decreases in vehicle speed and engine fan speed, a control system comprising: 
 a pressure sensitive control valve having an input port, an output port, a valve between the input port and output port, and a pressure sensing mechanism coupled to the valve for providing a displacement movement thereto as a function of sensed pressure for controlling the size of the valve opening;    means for coupling the input and output ports of the pressure sensitive valve in the air conditioning system at a point adjacent the evaporator, and means for coupling the pressure sensing mechanism to sense refrigerant pressure adjacent the evaporator so that the valve functions as a variable orifice to control the amount of refrigerant flow through the system for variations in compressor and condenser capacities in a direction to achieve heat absorption over substantially the entire evaporator while interacting with the accumulator by providing levels of liquid refrigerant flow as needed to control the amount active charge of the refrigerant in the system.    
     
     
         39 . A variable orifice control system for vehicular air conditioning systems including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein and wherein the vehicle engine drives the compressor so that the refrigerant pumping capacity of the compressor increases and decreases with increases and decreases in vehicle engine speed, and the heat rejection capacity of the condenser increases and decreases with air flow there through with increases and decreases in vehicle speed and engine fan speed, a control system comprising: 
 a pressure sensitive control valve having an input port, an output port a valve between the input port and output port, and a pressure sensing mechanism coupled to the valve for providing a displacement movement thereto as a function of sensed pressure for controlling the size of the valve opening;    means for coupling the input and output ports of the pressure sensitive valve in the air conditioning system between the condenser and the evaporator, and means for coupling the pressure sensing mechanism to sense refrigerant pressure adjacent the evaporator so that the valve functions as a variable orifice and interacts with the accumulator to vary the amount of refrigerant flowing in the system in a direction corresponding to changes in the compressor and condenser operating capacities.    
     
     
         40 . A variable orifice control system as defined in    claim 39    wherein the variable orifice and accumulator interact of change the cooling capacity of the system in a direction to follow the compressor and condenser operation capacities.  
     
     
         41 . A variable orifice control system as defined in    claim 39    wherein the variable orifice interacts with the accumulator to maintain the refrigerant charge of the system.  
     
     
         42 . In vehicular air conditioning systems including a compressor, a condenser, an evaporator and an accumulator connected in series for cyclic refrigerant flow therein and wherein the vehicle engine drives the compressor so that the refrigerant pumping capacity of the compressor increases and decreases with increases and decreases in vehicle engine speed, and the heat rejection capacity of the condenser increases and decreases with air flow there through with increases and decreases in vehicle speed and engine fan speed, a method for controlling the system comprising: 
 sensing the pressure of the refrigerant adjacent the evaporator;    controlling the flow of refrigerant through the evaporator with a valve that is responsive to the sensed pressure so as to function as a variable orifice to control refrigerant in a direction to adjust the cooling capacity of the system as a direct function of the compressor and condenser capacities.    
     
     
         43 . The method as defined in    claim 42    wherein: 
 the controlling step adjusts the cooling capacity of the system to increase as either or both the compressor and condenser capacities increase.  
 
     
     
         44 . The method as defined in    claim 43    wherein: 
 the sensed pressure corresponds to the output pressure of the evaporator, and the control step controls the flow of refrigerant in a direction so that the pressure at the output of the evaporator corresponds to saturated vapor wherein the refrigerant is substantially all vapor with a minor amount of liquid.  
 
     
     
         45 . The method as defined in    claim 44    wherein: 
 the controlling step interacts with the operation of the accumulator so as to provide levels of liquid refrigerant from the evaporator as needed to keep the active refrigerant in the system charged.  
 
     
     
         46 . The method as defined in    claim 46    wherein: 
 the sensing step includes adjusting the sensed pressure as a function of the flow rate of the refrigerant.