Pulse controlled expansion valve and method

Claim 2

Apparatus for controlling a refrigeration system, the latter comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to said condenser and to the inlet of said compressor, an expansion valve between said condenser and said evaparator, said condenser delivering high pressure liquid refrigerant to said expansion valve, said apparatus comprising a solenoid valve constituting said expansion valve, said solenoid valve having a valve body with a flow passage therewithin for the flow of refrigerant therethrough, a valve seat constituting a portion of said flow passage, a valve member selectively movable between a closed position in which it is sealingly engageable with said valve seat so as to block the flow of refrigerant through said flow passage and an open position in which said valve member is clear of said valve seat permitting the flow of refrigerant through said flow passage, said flow passage downstream from said valve seat having a metering orifice therein for restricting the flow of refrigerant through said flow passage to a predetermined flow rate when said valve member is open substantially independently of the distance said valve member is moved from its closed position, a solenoid actuator for effecting movement of said valve member between its closed and its open position upon energization and de-energization of said solenoid actuator, a spring for resiliently biasing said valve member toward one of its said positions, and control means for periodically energizing and de-energizing said solenoid actuator thereby to regulate the flow of refrigerant through said solenoid valve.

Claim 3

Apparatus as set forth in claim 1 wherein said control means includes means responsive to one or more operating parameters of said refrigeration system for varying the ratio of the energization time to the length of time of the period of said solenoid valve.

Claim 4

Apparatus as set forth in claim 2 wherein said control means includes means for sensing the superheat of the refrigerant discharged from said evaporator, means for generating a signal in response to the superheat of the refrigerant discharged from said evaporator, and means for comparing said signal to a predetermined value thereby to vary said energization time to period time ratio.

Claim 5

Apparatus as set forth in claim 2 wherein said evaporator has an inlet and an outlet, and wherein said control means includes means for sensing a temperature differential between said evaporator inlet and outlet, means for generating a signal in response to said temperature differential, and means for comparing said signal to a predetermined value thereby to vary said energization time to period time ratio.

Claim 6

Apparatus as set forth in claim 1 wherein said flow passage includes a chamber in communication with the outer surface of said valve member in sealing engagement with valve seat and a portion surrounded by said valve seat, the last-said portion of said flow passage having said metering orifice therewithin.

Claim 7

In a refrigeration system, said refrigeration system comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to said condenser and to the inlet of said compressor, an expansion valve between said condenser and said evaporator, said condenser delivering high pressure liquid refrigerant to said expansion valve, said refrigerant expanding as it flows through said expansion valve, wherein the improvement of this invention comprises: said expansion valve being a solenoid operated valve having a valve body with a flow passage therewithin for the flow of refrigerant therethrough, a valve seat constituting a portion of said flow passage, a valve member selectively movable between a closed position in which it is sealingly engageable with said valve seats so as to block the flow of refrigerant through said flow passage and an open position in which said valve member is clear of said valve seat permitting the flow of refrigerant through said flow passage, said flow passage downstream from said valve seat having a metering orifice therein for restricting the flow of refrigerant through said flow passage to a predetermined flow rate when said valve member is open substantially independently of the distance said valve member is moved from its closed position, a solenoid actuator for effecting movement of said valve member between its closed and its open position upon energization and de-energization of said solenoid actuator, a spring for resiliently biasing said valve member towards its closed position, and control means for periodically energizing and de-energizing said solenoid actuator with the ratio of energization time to the length of the period being responsive to one or more operating parameters of said refrigeration system thereby to regulate the flow of refrigerant through said expansion valve.

Claim 8

In a refrigeration system, said refrigeration system comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to said condenser and to the inlet of said compressor, an expansion valve between said condenser and said evaporator, said condenser delivering high pressure liquid refrigerant to said expansion valve, said refrigerant expanding as it flows through said expansion valve, wherein the improvement of this invention comprises: said expansion valve being a solenoid operated valve having a valve body with a flow passage therewithin for the flow of refrigerant therethrough, a valve seat constituting a portion of said flow passage, a valve member selectively movable between a closed position in which it is sealingly engageable with said valve seats so as to block the flow of refrigerant through said flow passage and an open position in which said valve member is clear of said valve seat permitting the flow of refrigerant through said flow passage, said flow passage downstream from said valve seat having a metering orifice therein for restricting the flow of refrigerant through said flow passage to a predetermined flow rate when said valve member is open substantially independently of the distance said valve member is moved from its closed position, a solenoid actuator for effecting movement of said valve member between its closed and its open position upon energization and de-energization of said solenoid actuator, a spring for resiliently biasing said valve member towards its closed position, and control means for periodically energizing and de-energizing said solenoid actuator with the ratio of energization time to the length of the period being responsive to one or more operating parameters of said refrigeration system thereby to regulate the flow of refrigerant through said expansion valve.

Claim 9

In a refrigeration system as set forth in claim 6 wherein said control means includes means for sensing the superheat of the refrigerant discharged from said evaporator, means responsive to said superheat for generating a signal in proportion to the superheat of the refrigerant discharged from said evaporator, and means for comparing said proportional signal to a predetermined value thereby to vary said energization time to period time ratio.

Claim 10

In a refrigeration system as set forth in claim 6 wherein said evaporator has an inlet and an outlet, and wherein said control means includes means for sensing a temperature differential between said evaporator inlet and outlet, means for generating a signal in response to said temperature differential, and means for comparing said signal to a predetermined value thereby to vary said energization time to period time ratio.

Claim 11

In a refrigeration system comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to said condenser and to the inlet of said compressor, an expansion valve between said condenser and said evaporator, said condenser delivering high pressure liquid refrigerant to said expansion valve, said refrigerant expanding as it flows through said expansion valve, wherein the improvement of this invention comprises: said expansion valve being a solenoid operated valve having a valve body with a flow passage therewithin for the flow of refrigerant therethrough, a valve seat constituting a portion of said flow passage, a valve member selectively movable between a closed position in which it is sealingly engageable with said valve seat so as to block the flow of refrigerant through said flow passage and an open position in which said valve member is clear of said valve seat permitting the flow of refrigerant through said flow passage, a solenoid actuator for effecting movement of said valve member between its closed and its open position upon energization and de-energization of said solenoid actuator, a spring for resiliently biasing said valve member towards its closed position, and control means for periodically energizing and de-energizing said solenoid actuator with the ratio of open time to the length of the period of said valve being responsive to one or more parameters of said refrigeration system thereby to regulate the flow of refrigerant through said expansion valve, said control means including means for sensing the superheat of the refrigerant discharged from said evaporator, means for generating a setpoint signal T 2 representative of a desired operating condition of the refrigeration system, said control means further including means for generating an integrator count signal corresponding to a predetermined ratio of valve open time to the length of the period which is greater than zero, said integrator count signal generating means further having means for comparing said superheat to said set point signal and if the difference between said superheat and said set point is less than zero, an increment will be subtracted from said predetermined ratio of energization time to the length of said period, and if the difference between said superheat and said set point is greater than zero, an increment will be added to said predetermined ratio of energization time to the length of said period.

Claim 12

In a refrigeration system comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of the compressor, an evaporator connected to said condenser and to the inlet of said compressor, an expansion valve between said condenser and said evaporator, said condenser delivering high pressure liquid refrigerant to said expansion valve, said refrigerant expanding as it flows through said expansion valve, wherein the improvement of this invention comprises: said expansion valve being a solenoid operated valve having a valve body with a flow passage therewithin for the flow of refrigerant therethrough, a valve seat constituting a portion of said flow passage, a valve member selectively movable between a closed position in which it is sealingly engageable with said valve seat so as to block the flow of refrigerant through said flow passage and an open position in which said valve member is clear of said valve seat permitting the flow of refrigerant through said flow passage, a solenoid actuator for effecting movement of said valve member between its closed and its open position upon energization and de-energization of said solenoid actuator, a spring for resiliently biasing said valve member towards its closed position, and control means for periodically energizing and de-energizing said solenoid actuator with the ratio of open time to the length of the period of said valve being responsive to one or more parameters of said refrigeration system thereby to regulate the flow of refrigerant through said expansion valve, said control means including means for sensing the superheat of the refrigerant discharged from said evaporator, means for generating a setpoint signal T 2 representative of a desired operating condition of the refrigeration system, said control means further including means for generating an integrator count signal corresponding to a predetermined ratio of valve open time to the length of the period which is greater than zero, said integrator count signal generating means further having means for comparing said superheat to said set point signal and if the difference between said superheat and said set point is less than zero, an increment will be subtracted from said predetermined ratio of energization time to the length of said period, and if the difference between said superheat and said set point is greater than zero, an increment will be added to said predetermined ratio of energization time to the length of said period.

Claim 13

In a refrigeration system as set forth in claim 9 wherein said control means includes means for generating a signal to increase the ratio of valve open time to the period proportional to the difference between the actual superheat of the system above said set point such that the percentage of open time of said valve to the period of the valve is the sum of integrator count signal and the proportional control signal.

Claim 14

Expansion apparatus for a refrigeration system, the latter comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of said compressor, and an evaporator, said expansion apparatus comprising a solenoid operated valve and means for controlling operation of said solenoid valve thereby to regulate the flow of refrigerant through said evaporator, said solenoid valve having a flow passage for the refrigerant therethrough and a valve member movable between an open position in which refrigerant is free to flow through said evaporator and a closed position in which the flow of refrigerant is blocked, a solenoid for effecting movement of said valve member between its open and closed positions, said control means periodically energizing and de-energizing said solenoid with the ratio of open time of said valve to the length of time of the period being responsive to one or more parameters of the refrigeration system thereby to regulate the flow of refrigerant to the evaporator, wherein said control means includes means for sensing the superheat of the refrigerant discharged from said evaporator, means responsive to said superheat for generating a signal in proportion to the superheat of the refrigerant discharged from said evaporator, and means for comparing said proportional signal to a predetermined value thereby to vary said ratio of open time to said period, said control means further including means for generating a set point signal and means for generating an integrator count signal corresponding to a predetermined value of said ratio which is greater than zero, said integrator count signal generating means further having means for comparing said superheat to said set point signal and if the difference between said superheat and said set point is less than zero, an increment will be subtracted from said ratio, and if the difference between said superheat and said set point is greater than zero, an increment will be added to said ratio.

Claim 15

Expansion apparatus for a refrigeration system, the latter comprising a compressor having an inlet and an outlet, a condenser connected to the outlet of said compressor, and an evaporator, said expansion apparatus comprising a solenoid operated valve and means for controlling operation of said solenoid valve thereby to regulate the flow of refrigerant through said evaporator, said solenoid valve having a flow passage for the refrigerant therethrough and a valve member movable between an open position in which refrigerant is free to flow through said evaporator and a closed position in which the flow of refrigerant is blocked, a solenoid for effecting movement of said valve member between its open and closed positions, said control means periodically energizing and de-energizing said solenoid with the ratio of open time of said valve to the length of time of the period being responsive to one or more parameters of the refrigeration system thereby to regulate the flow of refrigerant to the evaporator, wherein said control means includes means for sensing the superheat of the refrigerant discharged from said evaporator, means responsive to said superheat for generating a signal in proportion to the superheat of the refrigerant discharged from said evaporator, and means for comparing said proportional signal to a predetermined value thereby to vary said ratio of open time to said period, said control means further including means for generating a set point signal and means for generating an integrator count signal corresponding to a predetermined value of said ratio which is greater than zero, said integrator count signal generating means further having means for comparing said superheat to said set point signal and if the difference between said superheat and said set point is less than zero, an increment will be subtracted from said ratio, and if the difference between said superheat and said set point is greater than zero, an increment will be added to said ratio.

Claim 16

Expansion apparatus as set forth in claim 11 wherein said means for comparing said proportional signal and said predetermined value is inoperable so long as said predetermined value is greater than said proportional signal.

Claim 17

Expansion apparatus as set forth in claim 11 wherein the total percentage of the time said valve is open in relation to its period is the sum of the signal of the integration portion of the control system and the signal of the proportional control portion of the control system.

Claim 20

The method of claim 14 wherein said step of monitoring a parameter comprises monitoring the superheat of the refrigerant.

Claim 21

The method of claim 14 said evaporator has an inlet and an outlet, and wherein said step of monitoring a parameter comprises monitoring the temperature differential between the inlet and outlet of said evaporator.

Claim 22

The method of claim 14 further comprising generating a proportional signal in response to said parameter, and comparing said proportional signal and said set point signal such that if the difference between said set point signal and said proportional signal is greater than zero, then the percentage of valve open time to said period is the sum of said integrated count signal and said proportional signal.