Method and apparatus for monitoring and controlling the operation of a refrigeration unit

Claim 2

The method of claim 1 wherein the plurality of control components includes a predetermined control device (158) which enables starting of the refrigeration unit, and including the steps of: determining (240) if the unit should be started when the unit is found not running, energizing (252) the predetermined control device which enables the starting of the refrigeration unit, when the unit should be started, measuring (254) the magnitude of the current draw of the control circuit after the predetermined control device is energized, providing (256,258) a current draw window having upper and lower limits (258,256) which define an allowable current draw range for the control circuit with the predetermined control device energized, comparing (256,258) the latest measured current draw with the current draw window, starting (260) the unit when the measured current draw is within the limits of the current draw window, and de-energizing (262) the predetermined control device when the measured current draw is not within the limits of the current draw window.

Claim 3

The method of claim 2 wherein the refrigeration unit is operable in selectable different operating modes (270,274,278, 282,286,290), with the plurality of control devices including a control device associated with each operating mode, and including the steps of: running (252) the unit, after the starting step, in a predetermined initial operating mode, determining (268,272,276,280,284) when a different operating mode is required, energizing (294) the control device associated with the different operating mode, measuring (296) the magnitude of the current draw of the control circuit after the control device of the different operating mode is energized, providing (298,300) a current draw window having upper and lower limits ((298,300) which define an allowable current draw range for the control circuit with the control device of the different operating mode energized, comparing (298,300) the latest measured current draw with the current draw window, and initiating (302) the different operating mode when the latest measured current draw is within the limits of the current draw window.

Claim 4

The method of claim 3 including the steps of: providing (308,310) an alarm when the latest measured current draw is not within the limits of the current draw window, allowing (300,308,302) the unit to operate with the control device of the different operating mode energized when the latest measured current draw is less than the lower limit of the current draw window, and shutting (318) the unit down when the latest measured current draw exceeds the upper limit of the current draw window.

Claim 5

The method of claim 3 including the steps of: providing (308,310) an alarm when the latest measured current draw is not within the limits of the associated current draw window, allowing (300,308,302) the unit to operate with the control device of the different operating mode energized when the latest measured current draw is less than the lower limit of the associated current draw window, de-energizing (312) the control device when the latest measured current draw exceeds the upper limit of the associated current draw window, measuring (314) the current draw after the control device of the different operating mode is de-energized, providing (316) a maximum current reference value which indicates the maximum allowable current with the control device of the different operating mode de-energized, comparing (316) the latest measured current draw with the maximum current reference value, allowing (316,302) the unit to run with the control device of the different operating mode de-energized when the latest measured current draw does not exceed the maximum current reference value, and shutting (316,318) the unit down when the latest measured current draw exceeds the maximum current reference value.

Claim 6

The method of claim 2 wherein the starting step started the unit running, and wherein the refrigeration unit controls a conditioned space (90) to a predetermined null temperature range adjacent to a selected set point temperature via heating, cooling and null cycles, and including the steps of: determining (612) when conditions for a null cycle are satisfied, de-energizing (614) the control outputs of the controller when the determining step finds that conditions for a null cycle are satisfied, measuring (616) the magnitude of the current draw of the control circuit with the control outputs of the controller de-energized, providing (618) a current reference value which indicates the maximum allowable current draw with the control outputs of the controller de-energized, comparing (618) the latest measured current draw with the reference value, initiating (622) a null cycle when the latest measured current draw does not exceed the reference value, and providing (626) an alarm which indicates the controller should be checked when the latest measured current draw exceeds the reference value.

Claim 8

The method of claim 7 wherein the plurality of control devices includes a predetermined control device (158) which enables starting of the refrigeration unit, and including the steps of: determining (240) if the unit should be started when the unit is not running, energizing (252) the predetermined control device which enables the starting of the refrigeration unit, when the unit should be started, measuring (254) the magnitude of the current draw of the control circuit after the predetermined control device is energized, providing (256,258) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the predetermined control device energized, comparing (256,258) the latest measured current draw with the current draw window, starting (260) the unit when the measured current draw is within the limits of the current draw window, and de-energizing (262) the predetermined control device when the measured current draw is not within the current draw window.

Claim 9

The method of claim 8 including the step of running (252) the unit, after the starting step, in a predetermined initial operating mode.

Claim 10

The method of claim 8 including the step of providing (264) an alarm which indicates the predetermined control device should be checked when the latest measured current draw is not within the associated current draw window.

Claim 11

The method of claim 7 wherein the refrigeration unit is operable in low and high speed modes and the electrical control includes a high speed control device (162) controllable by an output (220) of the controller which is energized to change to a high speed mode, and including the steps of: determining (268) when a high speed mode is required, energizing (294) the high speed control device when the high speed mode is required, measuring (296) the magnitude of the current draw of the control circuit with the high speed control device energized, providing (298,300) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the high speed control device energized, comparing (298,300) the latest measured current draw with the current draw window, and initiating (304) the high speed mode when the latest measured current draw is within the current draw window.

Claim 12

The method of claim 11 including the steps of: providing (308,310) an alarm when the latest measured current draw is outside the associated current draw window, allowing (308,302) the unit to operate with the high speed control device energized when the measured current is below the lower limit of the current draw window, de-energizing (312) the high speed control device when the measured current draw exceeds the upper limit of the current draw window, measuring (314) the current draw after the high speed control device is de-energized, providing (316) a maximum allowable current reference value, comparing (316) the latest measured current draw with the reference value, allowing (316,302) the unit to operate with the high speed control device de-energized when the comparison step finds that the measured current draw does not exceed the reference value, and shutting (316,318) the unit down when the comparison step finds that the measured current draw exceeds the reference value.

Claim 13

The method of claim 7 wherein the refrigeration unit is operable in cooling and heating modes and the electrical control includes a heat control device (160) controllable by an output (224) of the controller which is energized to change from a cooling mode to a heating mode, and including the steps of: determining (272) when a heating mode is required, energizing (322) the heat control device, measuring (324) the magnitude of the current draw of the control circuit with the heat control device energized, providing (326,328) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the heat control device energized, comparing (326,328) the latest measured current draw with the current draw window, and initiating (330,332) the heating mode when the measured current draw is within the current draw window.

Claim 14

The method of claim 13 wherein the refrigeration unit controls the temperature of a conditioned space to a selected set point temperature, and including the steps of: determining (346) if the selected set point temperature is above or below a predetermined value which respectively indicates non-frozen and frozen loads in the conditioned space, allowing (346,330) the unit to operate with the heat control device energized when the latest measured current draw is below the lower limit of the current draw window and the selected set point temperature indicates a frozen load, shutting (346,344) the unit down when the measured current draw is below the lower limit of the current draw window and the selected set point temperature indicates a non-frozen load, de-energizing (338) the heat control device when the latest measured current draw exceeds the upper limit of the current draw window, measuring (340) the current draw after the heat control device is de-energized, providing (342) a maximum allowable current reference value, comparing (342) the latest measured current draw with the reference value, allowing (342) the unit to operate with the heat control device de-energized when the comparison step finds that the latest measured current draw does not exceed the reference value and the selected set point temperature indicates a frozen load, shutting (342,344) the unit down when the comparison step finds that the latest measured current draw exceeds the reference value, and shutting (342,346,344) the unit down when the comparison step finds that the latest measured current draw is less than the reference value and the selected set point temperature indicates a non-frozen load.

Claim 15

The method of claim 13 wherein the refrigeration unit is operable in low and high speed modes and the electrical control includes a high speed control device (162) controllable by an output (224) of the controller which is energized to change to a high speed heat mode, and including the steps of: determining (276) when a high speed heat mode is required when the heat control device is energized, energizing (366) the high speed control device, measuring (368) the magnitude of the current draw of the control circuit with the heat control device and the high speed control device energized, providing (370,372) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the heat control device and the high speed control device energized, comparing (370,372) the latest measured current draw with the current draw window, and initiating (372,360,362) the high speed heat mode when the measured current draw is within the limits of the current draw window.

Claim 16

The method of claim 15 including the steps of: providing (376,374) an alarm when the latest measured current draw is outside the limits of the current draw window, allowing (372,374,360) the unit to operate with the high speed control device energized when the latest measured current draw is below the lower limit of the current draw window, de-energizing (378) the high speed control device when the measured current draw exceeds the upper limit of the current draw window, measuring (380) the current draw after the high speed control device is de-energized, providing (382) a maximum allowable current reference value, comparing (382) the latest measured current draw with the reference value, allowing (382,360) the unit to operate with the high speed control device de-energized when the comparison step finds that the latest measured current draw does not exceed the reference value, and shutting (382,384) the unit down when the comparison step finds that the latest measured current draw exceeds the reference value.

Claim 17

The method of claim 7 wherein the refrigeration unit is operable in a defrost mode, with the refrigeration unit including an evaporator coil (62), a defrost damper (93), and a damper control device (164) controllable by an output (218) of the controller, and including the steps of: determining (280) when a defrost mode should be initiated to defrost the evaporator coil, energizing (388) the damper control device when a defrost mode is required, measuring (390) the magnitude of the current draw of the control circuit with the damper control device energized, providing (392,394) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the damper control device energized, comparing (392,394) the latest measured current draw with the current draw window, providing (396) an alarm when the latest measured current draw is outside the limits of the current draw window, de-energizing (398) the damper control device when the measured current draw is outside the limits of the current draw window, measuring (400) the current draw after the damper control device is de-energized, providing (402) a maximum allowable current reference value, comparing (402) the latest measured current draw with the reference value, allowing (402,410,412) the unit to operate with the damper control device de-energized, and disabling (410) the defrost mode, when the comparison step finds that the latest measured current draw does not exceed the reference value, and shutting (404) the unit down when the comparison step finds that the latest measured current draw exceeds the reference value.

Claim 18

The method of claim 17 wherein the control includes a heat control device (160) controllable by an output (224) of the controller, and including the steps of: storing (416) the measured current draw when the current draw for the damper control device is within the limits of the associated current draw window, energizing (418) the heat control device when the current draw for the damper control device is within the limits of the associated current draw window, measuring (420) the magnitude of the current draw of the control circuit with the damper control device and the heat control device energized, providing (422,434) a current draw window having upper and lower limits which include the value stored in the storing step, to provide a current draw window which defines an allowable current draw range for the control circuit with the heat control device and damper control device both energized, comparing (422,434) the latest measured current draw with the associated current draw window, and initiating (434) the defrost mode when the latest measured current draw is within the current draw window.

Claim 19

The method of claim 18 including the steps of: providing (424) an alarm when the measured current draw with the damper control device and the heat control device both energized is outside the associated current draw window, de-energizing (426) the heat control device when the measured current draw with the damper control device and the heat control device both energized is outside the current draw window, measuring (428) the current draw after the heat control device is de-energized, when the upper limit of the associated current draw window is exceeded, comparing (430) the latest measured current draw with the stored current draw, shutting (430,404) the unit down when the measured current draw exceeds the stored current draw, de-energizing (398) the damper control device when the measured current draw does not exceed the stored current draw, and also when the measured current draw with both the damper and heat control devices energized is below the lower limit of the associated current draw window, measuring (400) the current draw after the damper control device is de-energized, providing (402) a maximum allowable current draw reference value, comparing (402) the latest measured current draw with the reference value, allowing (402,410,412,414) the unit to operate with the damper control device de-energized when the latest measured current draw does not exceed the reference, and shutting (402,404) the unit down when the comparison step finds that the latest measured current draw exceeds the reference value.

Claim 20

The method of claim 18 including the steps of: detecting (440) when the defrost mode should be terminated, de-energizing (444) the heat control device when the detecting step detects termination of defrost, measuring (446) the current draw after the heat control device is de-energized, comparing (448) the latest measured current draw with the stored current draw, providing (450) an alarm when the latest measured current draw exceeds the stored current draw, shutting (452) the refrigeration unit down when the latest measured current draw exceeds the stored current draw, de-energizing (462) the damper control device when the measured current draw does not exceed the stored current draw, measuring (464) the current draw after the damper control device is de-energized, providing (466) a maximum allowable current reference value, comparing (466) the latest measured current draw with the reference value, allowing (466,468,470) the unit to run when the comparison step finds the latest measured current draw does not exceed the reference value, providing (472) an alarm when the comparison step finds the latest measured current draw exceeds the reference value, and shutting (474) the unit down when the comparison step finds the latest measured current draw exceeds the reference value.

Claim 21

The method of claim 20 including the step of providing (454,456,458) a delay before the damper control device is de-energized, to allow the evaporator coil to cool before the defrost damper is opened by the damper control device.

Claim 22

The method of claim 7 wherein the refrigeration unit is operable in a hot gas by-pass mode and the electrical control includes a hot refrigerant gas by-pass control device (166) controllable by an output of the controller which is energized to initiate a hot gas by-pass mode, and including the steps of: determining (284) when a hot gas by-pass mode is required, energizing (478) the hot gas by-pass control device, measuring (480) the magnitude of the current draw of the control circuit with the hot gas by-pass control device energized, providing (482,500) a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the hot gas by-pass control device energized, comparing (482,500) the latest measured current draw with the current draw window, providing (484,504) an alarm when the latest measured current draw is outside the limits of the current draw window, de-energizing (502) the hot gas by-pass control device when the latest measured current draw is less than the lower limit of the current draw window, allowing (500,502,504,496) the unit to run with the hot gas by-pass control device energized when the latest measured current draw is less than the lower limit of the current draw window, de-energizing (486) the hot gas by-pass control device when the latest measured current draw exceeds the upper limit of the current draw window, measuring (488) the current draw after the hot gas by-pass control device is de-energized, providing (490) a maximum allowable current reference value for the current draw with the hot gas by-pass control device de-energized, comparing (490) the latest measured current draw with the reference value, allowing (490,496) the unit to run with the hot gas by-pass control device de-energized when the latest measured current draw does not exceed the reference value, and shutting (490,492) the unit down when the latest measured current draw exceeds the reference value.

Claim 23

The method of claim 22 wherein the refrigeration unit is operable in a suction line modulation mode, and the refrigeration unit includes a suction line modulation valve (64), and including the steps of: determining (506) if the suction line modulation mode is required after the measured current draw is found to be within the associated current draw window, operating (506,508,510) the unit with the hot gas by-pass control device energized when the determining step finds that the modulation mode is not required, storing (514) the measured current draw when the determining step finds that the modulation mode is required, energizing (516) the modulation valve when the determining step finds that the modulation mode is required, measuring (518) the current draw after the step of energizing the modulation valve, providing (520,584) a current draw window having upper and lower limits which include the stored value, defining an allowable current draw range for the control circuit with the hot gas by-pass control device and modulation valve both energized, comparing (520,584) the latest measured current draw with the current draw window, and initiating (584,590,594,596,598) the hot gas by-pass mode with the modulation mode when the latest measured current draw is within the limits of the associated current draw window.

Claim 24

The method of claim 22 including the steps of: determining (594) when the modulation mode is not required, de-energizing (600) the modulation valve when the modulation mode is not required, measuring (602) the current draw after the de-energizing step, comparing (604) the latest measured current draw with the stored value, allowing (604,608,508,510) the unit to operate with the modulation valve de-energized when the comparison step finds the latest measured current draw does not exceed the stored value, and shutting (604,606,530) the unit down when the comparison step finds that the latest measured current draw exceeds the stored value.

Claim 25

The method of claim 22 including the steps of: providing (522) an alarm and de-energizing (588) the modulation valve when the measured current draw with the hot gas by-pass control device and modulation valve both energized is not within the associated current draw window, allowing (584,586,588,608,508,510) the unit to operate when the measured current draw is less than the lower limit of the current draw window, measuring (526) the current draw after the step of de-energizing the modulation valve when the latest measured current draw exceeds the upper limit of the current draw window, comparing (528) the latest measured current draw with the stored value, allowing (528,508,510) the unit to run when the latest measured current draw does not exceed the stored value, and shutting (528,530) the unit down when the latest measured current draw exceeds the stored value.

Claim 26

Control apparatus (94) for monitoring and controlling the operation of a refrigeration unit (20), with the electrical control apparatus including a voltage source (127), a control circuit (98) which includes a plurality of control devices, and a controller (96) which selectively activates the control devices via a plurality of control outputs, characterized by: a current shunt (131) disposed between the voltage source and the control circuit, means (238) determining if the refrigeration unit is operating, means (242) de-energizing the control outputs of the controller when the refrigeration unit is not operating, means (244) measuring the magnitude of the current draw of the control circuit with the control outputs of the controller de-energized, means (246) providing a current reference value which indicates the maximum allowable current draw with the control outputs of the controller de-energized, means (246) comparing the measured current draw with the reference value, and means (250) providing an alarm which indicates the controller should be checked when the measured current draw exceeds the reference value.

Claim 27

The apparatus of claim 26 characterized by the fact that it includes: means (240) for determining if the unit should be started when the unit is found not running, a control device (158) which, when energized, enables the starting of the refrigeration unit, means (252) energizing said control device, means (254) measuring the magnitude of the current flow through the current shunt with the control device energized, means (256,258) providing a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the control device energized, means (256,258) comparing the latest measured current draw with the current draw window, means (260) starting the unit when the latest measured current draw is within the limits of the current draw window, and means (262) de-energizing the control device when the latest measured current draw is not within the limits of the current draw window.

Claim 28

The apparatus of claim 27 characterized by the fact that it includes: means (158) operating the unit, after starting, in a predetermined initial operating mode which requires continuous energization of the control device by the controller, means (98) providing a plurality of different operating modes, including a control device (160,162,164,166) controllable by an output of the controller for each of the plurality of different operational modes, means (268,272) determining when a different operating mode is desired, means (294,322) energizing the control device associated with the different operating mode, means (296) measuring the magnitude of the current flowing through the current shunt when the control device of the different mode energized, means (298,300) providing a current draw window having upper and lower limits which define an allowable current draw range for the control circuit with the control device of the different mode energized, means (298,300) comparing the latest measured current draw with the current draw window, and means (304) initiating the desired different operating mode when the measured current draw is within the limits of the current draw window.

Claim 29

The apparatus of claim 28 characterized by the fact that it includes: means (308,310) providing an alarm when the latest measured current draw is not within the limits of the associated current draw window, means (300,308,302,304) allowing the unit to operate when the latest measured current draw is below the lower limit of the current draw window, means (318) de-energizing the control device when the latest measured current draw exceeds the upper limit of the current draw window, means (314) measuring the current draw with the control device de-energized, means (316) providing a maximum current reference value, means (316) comparing the latest measured current draw with the maximum current reference value, means (316,302) allowing the unit to run when the latest measured current draw does not exceed the maximum current reference value, and means (316,318) shutting the unit down when the latest measured current draw exceeds the maximum current reference value.

Claim 30

The apparatus of claim 26 characterized by the fact that the voltage source (127) includes a battery (126) and generator means (138), and including an additional current shunt (130) connected to measure battery current.