WO2014165248A1

WO2014165248A1 - Method and apparatus for improving the charge accuracy of a refrigerant recovery unit having a check valve device and temperature controlled service hoses

Info

Publication number: WO2014165248A1
Application number: PCT/US2014/024967
Authority: WO
Inventors: Mark Mcmasters; Dylan LUNDBERG; William Brown; Gary Murray
Original assignee: Bosch Automotive Service Solutions Llc; Robert Bosch Gmbh
Priority date: 2013-03-12
Filing date: 2014-03-12
Publication date: 2014-10-09
Also published as: CN105209838B; EP2972017A1; EP2972017A4; CN105209838A; EP2972017B1

Abstract

A refrigerant recovery unit with improved charging accuracy is provided. A service hose that includes a service coupler and a check valve A refrigerant recovery unit with improved charging accuracy is provided. A service hose includes a service coupler and a check valve assembly. The assembly is disposed proximal to the service coupler and includes a recovery flow and recharge flow path. The assembly is configured to provide a substantially free flow of refrigerant and also configured to provide a predetermined cracking pressure in response to the refrigerant being urged to flow along the recharge flow path. The disclosure includes thermally conditioning the interior of the service hoses based on one or more temperature reading(s) and/or based on a function and may be achieved by a heater along the length of the hose, recirculating refrigerant, and/or through a parallel line of heated liquid.

Description

METHOD AND APPARATUS FOR IMPROVING THE CHARGE ACCURACY OF A REFRIGERANT RECOVERY UNIT HAVING A CHECK VALVE DEVICE AND TEMPERATURE CONTROLLED SERVICE HOSES

FIELD OF THE DISCLOSURE

[0001] The disclosure generally relates to a refrigerant recovery unit and associated methods for charging refrigerant into refrigeration systems. More particularly, the apparatus and methods used to improve the charge accuracy of the refrigerant recovery unit, such as by controlling the temperature of one or more refrigerant service hose(s). Additionally, the disclosure relates to an improved check valve assembly for servicing the refrigeration systems and a method of utilizing the improved check valve assembly with a refrigerant recovery unit.

BACKGROUND OF THE DISCLOSURE

[0002] Refrigeration systems are currently commonplace in commercial and residential buildings, and a variety of vehicles including, for example, automobiles, aircrafts, watercrafts, and trains. Over time, the refrigerant included in refrigeration systems is depleted and/or contaminated. As such, in order to maintain the overall efficiency and efficacy of a refrigeration system, the refrigerant included therein may be periodically replaced or recharged.

[0003] Refrigerant recovery units or carts are used in connection with the service and maintenance of refrigeration systems, such as air conditioning (A/C) systems. The refrigerant recovery unit connects to the A/C system to recover refrigerant out of the system and separate out oil and contaminants from the refrigerant in order to recharge or replace refrigerant into the A/C system.

[0004] Currently available processes for replacing the refrigerant contained in air conditioning systems typically include, evacuating the refrigerant contained in an A/C system, either, charging refrigerant evacuated or transferring new refrigerant into a refrigerant recovery unit storage tank, and transferring the refrigerant from the refrigerant recovery unit into the A/C system. In order to estimate how much refrigerant has been transferred to the A/C system, the refrigerant recovery unit typically includes a refrigerant container that is weighed before and after some refrigerant has been transferred into the A/C system.

[0005] The ability to obtain accurate weight measurements to get an accurate assessment of how much refrigerant entered the A/C system is important to provide proper servicing. Inaccurate weight measurements result in inaccurate assessments of how much refrigerant actually entered the A/C system during the charge, which can result in undercharging or overcharging the A/C system causing it to underperform. Consequently, in the automotive field, for example, the Society of Automotive Engineering (SAE) requires that refrigerant charging equipment have a charging accuracy of at least +/- 15 grams in order to meet certification standards.

[0006] Refrigerant charging often needs to be conducted over a wide range of ambient and system conditions. Fluctuating conditions make the measuring and compensating for refrigerant charging changes difficult with existing charging equipment. For example, exposure of portions of the service hoses to a wide range of temperature ranges can cause undercharging as refrigerant tends to condense and remain in the cooler sections of refrigerant flow paths. Previously and currently used methods to equalize and clear flow paths are not optimal and sometimes forbidden by manufacturers' specified charging requirements.

[0007] Portable refrigerant recovery units or carts are also used in connection with the service and maintenance of refrigeration systems, such as a vehicle's air conditioning system. The refrigerant recovery unit connects to the air conditioning system of the vehicle to recover refrigerant out of the system, separate out oil and contaminants from the refrigerant in order to recycle the refrigerant, and recharge the system with additional refrigerant.

[0008] Overcharging or undercharging a refrigeration system, such as an air conditioning system, may cause damage to the system and/or decrease the efficiency of the system. Vehicle air conditioning systems are typically small systems with relatively small amounts of refrigerant as compared to residential and commercial air conditioning systems. As such, it is relatively more important that the vehicle air conditioning systems be recharged with refrigerant accurately. However, due to many environmental variables and extremes in temperature experienced within the engine compartment of the vehicle, the state of the refrigerant (e.g., liquid or vapor) in the service hoses is often difficult to know. This, in turn, may lead to significant over or under charging.

[0009] As a consequence of the foregoing, a need exists for a refrigerant recovery unit and methods associated therewith that can improve the charge accuracy of a refrigerant recovery unit.

SUMMARY OF THE DISCLOSURE

[0010] Accordingly, the foregoing needs are met, to a great extent, by the present disclosure, wherein in one aspect, a refrigerant recovery unit can purge vapor refrigerant from the service hoses before taking a reference weight measurement. Lack of vapor in the service hoses provides for the ability to obtain more precise measurements of the amount of refrigerant that is actually transferred into the refrigeration system. Additionally, the refrigerant recovery unit is also configured with increased accuracy. Further, an improved check valve assembly for servicing a refrigeration system is also provided.

[0011] According to aspects of the disclosure, in some embodiments, a refrigerant recovery unit includes a charging circuit configured to charge the refrigerant into a refrigerant system in fluid connection to one or more service hoses, a refrigerant container in fluid communication with the charging circuit, a scale capable of measuring the weight of the refrigerant container, and a recirculating circuit configured to recirculate refrigerant from one end of the one or more service hoses to the refrigerant recovery unit.

[0012] According with aspects of the disclosure, a method of improving refrigerant charge accuracy using a refrigerant recovery unit is provided. The method including: connecting a first end of a first service hose to the recharging unit and a second end of the first service hose to a refrigerant system; opening a recirculating flow path in connection to one end of one or both the first service hose and the second service hose; measuring an initial reference weight of a refrigerant container after vapor refrigerant has been removed from the one or both service hoses through the recirculating flow path; opening a valve to transfer refrigerant to the refrigerant system; and measuring a second weight of the refrigerant container.

[0013] According with aspects of the disclosure, an additional method of improving refrigerant charge accuracy using a refrigerant recovery unit is provided. The method including: connecting a first end of a first service hose to the recharging unit and a second end of the first service hose to a refrigerant system; connecting a first end of a second service hose to the recharging unit and a second end of the second service hose to a refrigerant system; opening a recirculating flow path in connection to one end of one or both the first service hose and the second service hose; and keeping a constant flow before and after a valve regulating the refrigerant leaving the refrigerant recovery unit.

[0014] The refrigerant recovery unit can include a refrigerant storage tank configured to store a refrigerant, one or more service hoses configured to facilitate transfer of the refrigerant from the refrigerant storage tank to a refrigerant system, a first temperature sensor configured to determine a first temperature within the one or more service hoses, a second temperature sensor configured to determine a second temperature within the refrigerant recovery unit, and a controller configured calculate a first temperature differential between the first and second temperatures, and using the temperature differential to control a heater used to thermally control the temperature within the one or more service hoses.

[0015] In yet additional aspects of the disclosure, a method of adding refrigerant to a refrigerant system is disclosed. The method which can include obtaining a recommended amount of refrigerant for the refrigerant system, obtaining a first temperature reading, conditioning the interior temperature of one or both service hose(s) according to said first reference temperature, and charging the refrigerant system with a recommended amount of refrigerant.

[0016] In additional aspects of the disclosure, a refrigerant recovery unit can include a heater capable of heating the interior of said one or more service hoses before the transfer of refrigerant to a refrigerant system. The heater may be in communication and controlled by a controller which can also be in communication with one or more temperature sensors, the controller controlling the heater based on one or both temperature readings received and a preprogrammed function.

[0017] An embodiment of the present invention pertains to a refrigerant recovery system. The refrigerant recovery system includes a service hose and a refrigerant recovery unit. The service hose includes a service coupler, a check valve assembly, and a hose. The service coupler is configured to fluidly connect the service hose to a refrigeration system. The hose is to convey a refrigerant. The check valve assembly is disposed proximal to the service coupler. The check valve assembly includes a recovery flow path and a recharge flow path. The recovery flow path is defined by a flow of the refrigerant from the refrigeration system and flows along a first bore disposed in a body, a recovery poppet, a first O-ring, and a stand-off. The recharge flow path is defined by a flow of the refrigerant to the refrigeration system and flows along a second bore disposed in the body, a recharge poppet, a second O- ring, a biasing member, and a shim. The check valve assembly is configured to provide a substantially free flow of refrigerant along the recovery flow path and the check valve assembly is configured to provide a predetermined cracking pressure in response to the refrigerant being urged to flow along the recharge flow path. The refrigerant recovery unit includes a refrigerant storage unit, a refrigerant circuit, a processor, and a memory. The refrigerant storage unit is configured to store the refrigerant. The refrigerant circuit is in fluid connection with the refrigeration system. The refrigerant circuit is configured to recover refrigerant from the refrigeration system and recharge the refrigeration system with the refrigerant. The processor is configured to control the refrigerant recovery unit. The memory is to store diagnostic software and operating software to operate the refrigerant recovery unit.

[0018] Another embodiment of the present invention relates to a service hose. The service hose includes a service coupler, a check valve assembly, and a hose. The service coupler is configured to fluidly connect the service hose to a refrigeration system. The hose is to convey a refrigerant. The check valve assembly is disposed proximal to the service coupler. The check valve assembly includes a recovery flow path and a recharge flow path. The recovery flow path is defined by a flow of the refrigerant from the refrigeration system and flows along a first bore disposed in a body, a recovery poppet, a first O-ring, and a stand- off. The recharge flow path is defined by a flow of the refrigerant to the refrigeration system and flows along a second bore disposed in the body, a recharge poppet, a second O-ring, a biasing member, and a shim. The check valve assembly is configured to provide a substantially free flow of refrigerant along the recovery flow path and the check valve assembly is configured to provide a predetermined cracking pressure in response to the refrigerant being urged to flow along the recharge flow path.

[0019] Yet another embodiment of the present invention pertains to a method of servicing a refrigeration system. In this method, a refrigerant is recovered from the refrigeration system and the refrigeration system is recharged with the refrigerant. The refrigerant is recovered from the refrigeration system with a refrigeration recovery unit. The refrigeration recovery unit is in fluid communication with the refrigeration system via a service hose. The service hose includes a service coupler, a check valve assembly, and a hose. The service coupler is configured to fluidly connect the service hose to a refrigeration system. The hose is to convey a refrigerant. The check valve assembly is disposed proximal to the service coupler. The check valve assembly includes a recovery flow path and a recharge flow path. The recovery flow path is defined by a flow of the refrigerant from the refrigeration system and flows along a first bore disposed in a body, a recovery poppet, a first O-ring, and a stand-off. The recharge flow path is defined by a flow of the refrigerant to the refrigeration system and flows along a second bore disposed in the body, a recharge poppet, a second O-ring, a biasing member, and a shim. The check valve assembly is configured to provide a substantially free flow of refrigerant along the recovery flow path and the check valve assembly is configured to provide a predetermined cracking pressure in response to the refrigerant being urged to flow along the recharge flow path. The refrigeration system is recharged with the refrigerant by urging the refrigerant to flow from the refrigeration recovery unit at a pressure greater than the predetermined cracking pressure of the check valve assembly.

[0020] There has thus been outlined, rather broadly, certain aspects of the disclosure in order that the detailed description herein may be better understood, and in order that the present contribution to the art may be better appreciated. [0021] In this respect, before explaining at least one embodiment of the disclosure in detail, it is to be understood that the disclosure is not limited in its application to the details of the construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The disclosure is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.

[0022] As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present disclosure. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a front view of an exemplary refrigerant recovery unit according to aspects of the disclosure.

[0024] FIG. 2 illustrates exemplary components of the refrigerant recovery unit of FIG. 1 according to aspects of the disclosure.

[0025] FIG. 3 illustrates exemplary components of the refrigerant recovery unit of FIG. 1 according to aspects of the disclosure.

[0026] FIG. 4 illustrates exemplary components of another refrigerant recovery unit according to aspects of the disclosure.

[0027] FIG. 5 illustrates a flow chart to achieve increased accuracy of the amount of refrigerant used to recharge/charge an A/C system according to aspects of the disclosure.

[0028] FIG. 6 is a flow diagram illustrating exemplary components of the refrigerant recovery unit of FIG. 1 according to aspects of the disclosure.

[0029] FIG. 7 is an illustration of a refrigerant recovery unit connected to a refrigerant system of a vehicle and an enlarged cross section of a service hose according to aspects of the disclosure. [0030] FIG. 8 is a schematic diagram of some components included within and/or that may be connected to a refrigerant recovery unit.

[0031] FIG. 9 is a flowchart illustrating method steps to charge a refrigerant system according to embodiments of the disclosure.

[0032] FIG. 10 is a flowchart illustrating method steps to charge a refrigerant system according to additional embodiments of the disclosure.

[0033] FIG. 11 is a perspective view of a refrigerant recovery system in accordance with an embodiment of the invention.

[0034] FIG. 12 is a perspective view of a service hose in accordance with the embodiment of FIG. 11.

[0035] FIG. 13 is cut away view of a parallel flow check valve assembly in an idle conformation in accordance with the embodiment of FIG. 1 1.

[0036] FIG. 14 is cut away view of the parallel flow check valve assembly in a recovery conformation in accordance with the embodiment of FIG. 1 1.

[0037] FIG. 15 is cut away view of a parallel flow check valve assembly in a charging conformation in accordance with the embodiment of FIG. 1 1.

[0038] FIG. 16 is a perspective view of components suitable for use in the parallel flow check valve assembly according to FIGS 13-15.

[0039] FIG. 17 is a schematic diagram illustrating components of the refrigerant recovery unit shown in FIG. 1 1 in accordance with an embodiment of invention.

[0040] FIG. 18 is a block diagram illustrating aspects of a control system, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0041] Refrigerant recovery units or carts are used in connection with the service and maintenance of refrigeration systems. The refrigerant recovery unit connects to the refrigerant system to recover refrigerant out of the system, separate out oil and contaminants from the refrigerant in order to recycle the refrigerant, and recharge the refrigerant system.

[0042] According to aspects of the present disclosure, a refrigerant recovery unit that can be configured to more accurately transfer refrigerant to refrigeration systems, including for example, A/C systems found in residential and commercial buildings, and a variety of vehicles including, automobiles, aircrafts, watercrafts, and trains, is provided. The refrigerant recovery unit at can include temperature controlled refrigerant service hoses leading to the refrigeration systems. The refrigerant recovery unit can recover, recharge and/or replace an amount of depleted and/or contaminated refrigerant with increased accuracy thereby maintaining the overall efficiency and efficacy of the refrigerant system.

[0043] In some embodiments of the present disclosure, a refrigerant flow path conduit connected from the coupler containing ends of the service hoses and back to the oil separator is included. The refrigerant flow path conduit can be controlled, for example, by one or more solenoid valve(s). In some refrigerant recovery units, the refrigerant flow path conduit may be a refrigerant conduit portion of a circuit used for the recovery process, or a separate charging refrigerant flow path conduit that leads into the oil separator. The solenoid valve(s) can be capable of opening the flow path inside the conduit to thereby create a loop system that passes through the oil separator, purging vapor refrigerant in the lines, and back into the storage tank to fill the service hoses completely with refrigerant.

[0044] In some embodiments according to aspects of the disclosure, in said recovery units where the charging flow path conduit and the recovery flow path conduit leading towards the oil separator are separate, the diameter of the charge flow path conduit can be reduced. By reducing the diameter of the charge flow path, improved control of the refrigerant results, and additionally, the charge path can be kept from left over contamination resulting from recovered refrigerant remaining in the flow path conduit. [0045] According to various embodiments described herein, a refrigerant recovery system is provided that facilitates the servicing of a refrigeration system. As used herein, the term, "servicing" refers to any suitable procedure performed on a refrigeration system such as, for example, recovering refrigerant, testing refrigerant, leak testing the refrigeration system, recharging refrigerant into the refrigeration system, purifying the refrigerant to remove contaminants, recovering the lubricant, replacing the lubricant, and the like. In an embodiment, the refrigerant recovery system disclosed herein includes improved servicing hoses. In this or other embodiments, the servicing hoses include a check valve assembly that allows free flow of refrigerant during recovery operations and provides sufficient cracking pressure during recharging operations to maintain the refrigerant in a liquid state. For the purposes of this disclosure, the term, "cracking pressure" refers to a pressure at which flow through a valve starts. In this regard, one potential inaccuracy in determining an amount of refrigerant delivered to a refrigeration system is knowing the state of the refrigerant in the servicing hoses. For example, if the servicing hoses are cold enough, the refrigerant may be liquid even at relatively low pressure. Alternatively, at higher temperatures, the refrigerant may be gaseous. Depending upon the length and bore diameter of the servicing hoses, the volume may be great enough that the difference in weight between liquid and gaseous refrigerant represents a significant inaccuracy. By providing a cracking pressure configured to maintain the refrigerant in a liquid state throughout expected temperatures, the accuracy of the recharge can be improved. However, during recovery, it is preferable to have little or no cracking pressure so as to improve efficiency of the recovery. It is an advantage of one or more embodiments that the valve disclosed herein is configured to provide sufficient cracking pressure during recharging operations to maintain the refrigerant in a liquid state while allowing substantially unrestricted flow of refrigerant during recovery operations.

[0046] The disclosure will now be described with reference to the drawing figures. Throughout the description, the disclosure will now be described with reference to the drawings figures in which like reference numerals can refer to like parts throughout.

[0047] Beginning with FIG. 1, a front view of an exemplary refrigerant recovery unit 100 in accordance with some aspects of the disclosure is depicted. The refrigerant recovery unit 100 can include, for example, unit model number AC 1234 from Robinair based in Owatonna, MN (Service Solutions U.S. LLC). The refrigerant recovery unit 100 includes a cabinet or housing 102 to house components of the unit. The cabinet 102 may be made of any material such as thermoplastic, steel and the like.

[0048] The cabinet 102 includes a control panel 104 that allows the user to operate the refrigerant recovery unit 100. The control panel 104 may be part of the cabinet 102 as shown in FIG. 1 or separated. The control panel 104 includes high and low gauges 106, 108, respectively. The gauges may be analog or digital as desired by the user. The control panel 104 has a display 110 to provide information to the user, such as certain operating status of the refrigerant recovery unit 100 or provide messages or menus to the user. Located near the display 110 can be LEDs 112 to indicate to the user the operational status of the refrigerant recovery unit 100. The LEDs 1 12 may indicate that the refrigerant recovery unit 100 is in the recovery, recycling or recharging mode, or indicate that the filter (not shown) needs to be changed, that there is a malfunction, or other indicators.

[0049] A user interface 114 is also included on the control panel 104. The user interface 1 14 allows the user to interact and operate the refrigerant recovery unit 100 and can include an alphanumeric keypad and directional arrows. A power switch 118 or emergency shut off control can be included as part of the user interface 1 14. A printer 116 is provided to print out information, such as test results.

[0050] The cabinet 102 further includes connections for hoses 124, 128 that connect the refrigerant recovery unit 100 to a refrigerant containing device, such as a refrigerant system 200 (shown in FIG. 2). Also shown in FIG. 1, a connector interface 130 is provided so that a communication cable can be connected from the connector interface 130 to a data link connector included in some A/C systems. This can allow the refrigerant recovery unit 100 to communicate with an A/C system's controller (not shown) and diagnose any issues with it. In order for the refrigerant recovery unit 100 to be mobile, wheels 120 are provided at a bottom portion of the system.

[0051] Referring now to FIGS. 2-4, some components included within and/or that may be included in refrigerant recovery units are depicted in flow diagrams according to the present disclosure. In the following section, general functionality of recovery units and components are described.

[0052] In some embodiments, to service the A/C system, the service hoses 124, 128 can be coupled to the refrigerant system 200, via couplers 226 (high side) and 230 (low side), respectively. The couplers 226, 230 can be designed to be closed until they are coupled to the refrigerant system 200.

Recovery Cycle

[0053] The recovery cycle can be initiated by the opening of high pressure and low- pressure solenoids 276, 278, respectively. This allows the refrigerant within the refrigerant system 200 to flow through a recovery valve 280 and a check valve 282. The refrigerant flows from the check valve 282 into a system oil separator 262, where it travels through a filter/dryer 264, to an input of a compressor 256. Refrigerant is drawn through the compressor 256 through a normal discharge solenoid 284 and through a compressor oil separator 286, which circulates oil back to the compressor 256 through an oil return valve 288. The refrigerant recovery unit 100 may include a high-pressure switch 290 in communication with a controller 216, which can be programmed to determine an upper pressure limit, for example, 435 psi, to optionally shut down the compressor 256 to protect the compressor 256 from excessive pressure.

[0054] The controller 216 can also be, for example, a microprocessor, a field programmable gate array (FPGA) or application-specific integrated circuit (ASIC). The controller 216 via a wired or wireless connection (not shown) controls the various valves and other components (e.g. vacuum pump 258, compressor 256) of the refrigerant recovery unit 100. In some embodiments of the present disclosure, any or all of the electronic solenoid or electrically activated valves may be connected and controlled by the controller 216.

[0055] A high-side clear solenoid 323 may optionally be coupled to the output of the compressor 256 to release the recovered refrigerant transferred from the compressor 256 to a path leading into a storage tank 212, instead of through a path through the normal discharge solenoid 284. [0056] The heated compressed refrigerant can exit the system oil separator 262 and travel through a loop of conduit or heat exchanger 291 for cooling or condensing. As the heated refrigerant flows through the heat exchanger 291, the heated refrigerant gives off heat to the cold refrigerant in the system oil separator 262, and assists in maintaining the temperature in the system oil separator 262 within a working range. Coupled to the system oil separator 262 can be a switch or transducer 292, such as a low pressure switch or pressure transducer, for example, that senses pressure information, and provides an output signal to the controller 216 through a suitable interface circuit programmed to detect when the pressure of the recovered refrigerant is down to 13 inches of mercury, for example. An oil separator drain valve 293 can drain the recovered oil into a container 257. Finally, the recovered refrigerant can flow through a normal discharge check valve 294 along a refrigerant circuit 322 and, in some embodiments, through a vapor check valve 325 into the storage tank 212.

Evacuation Cycle

[0057] The evacuation cycle can begin by the opening of the high pressure and low- pressure solenoids 276, and 278 and a valve 296, leading to the input of a vacuum pump 258. Prior to opening the valve 296, an air intake valve (not shown) is opened, allowing the vacuum pump 258 to start exhausting air. The refrigerant of the refrigerant system 200 can then be evacuated by the closing of the air intake valve (not shown) and opening the valve 296, allowing the vacuum pump 258 to exhaust any trace gases remaining until the pressure is approximately 29 inches of mercury, for example. When this occurs, as detected by pressure transducers 231, 232, optionally, coupled to the high side 226 and low side 230 of the refrigerant system 200 and to the controller 216, the controller 216 may turn off the valve 296 allowing for the charging cycle to begin.

[0058] In embodiments where at least a portion of the recovery path conduit is shared with the flow path conduit leading to the oil separator for the charging process, as depicted in FIGS. 2 and 3, hose fill valves 401, 402 can remain open during the evacuation process. In other embodiments where there are separate paths for the evacuation and charging, as depicted in FIG. 4, the hose fill valves 401, 402 will preferably remain closed during the evacuation cycle to prevent oil contamination from the evacuated refrigerant.

Oil Draining

[0059] Also illustrated, a vacuum pump oil drain circuitry 250 that includes a vacuum pump oil drain valve 252 located along a vacuum pump oil drain conduit 254 connecting a vacuum pump oil drain outlet 259 to a container 257 for containing drained vacuum pump oil. The vacuum pump oil drain valve 252 may be electronically activated and controlled by the controller 216. The connection may be a wireless or wired connection. In other embodiments the vacuum pump oil drain valve 252 may be a manually activated valve that is actuated by a user. Additionally, a high pressure switch 289 can also be included and in communication with the controller 216 to optionally shut down the vacuum pump 258 when the pressure in the vacuum pump oil drain circuitry 250 exceeds a predetermined threshold. The vacuum pump oil drain conduit 254 may be a flexible hose or any other suitable conduit for providing fluid communication between the vacuum pump oil drain outlet 259 and the container 257.

Oil Purging

[0060] An air purging apparatus 308 is also illustrated. The air purging apparatus 308 allows the refrigerant recovery unit 100 to be purged of non-condensable, such as air. Air purged from the refrigerant recovery unit 100 may exit the storage tank 212, through an orifice 312, through a purging valve 314 and through an air diffuser 316. In some embodiments, the orifice 312 may be about 0.028 of an inch. A pressure transducer 310 can be used to measure the pressure contained within the storage tank 212 and the air purging apparatus 308 accordingly. For example, the pressure transducer 310 may send the pressure information to the controller 216, and when the pressure is too high, as calculated by the controller 216, purging is required. In addition or alternatively, a high pressure switch 31 1 may be included to shut off the system when pressure increases above a pre-determined level. [0061] The purging valve 314 may be selectively actuated to permit or not permit the air purging apparatus 308 to be open to the ambient conditions. A temperature sensor 317 may be coupled to the storage tank 212 to measure the refrigerant temperature therein. The placement of the temperature sensor 317 may be anywhere on the storage tank 212 or alternatively, the temperature sensor 317 may be placed within the refrigerant circuit 322. The measured temperature and pressure may be used to calculate the ideal vapor pressure for the type of refrigerant used in the refrigerant recovery unit 100. The ideal vapor pressure can be used to determine when the non-condensable gases need to be purged and how much purging will be done in order for the refrigerant recovery unit 100 to function properly.

Charging Cycle

[0062] For purposes of clarity and in accordance to aspects of the disclosure, the charging cycle is explained in reference to method steps 500 of FIG. 5 and flow diagrams illustrated in FIGS. 2-3. In particular, the method steps 500 can be used to charge the refrigerant system 200 with increased accuracy. At step 501, the service hoses 124, 128 can be coupled to the refrigerant system 200, via the couplers 226 (high side) and 230 (low side), respectively. In some embodiments, as depicted in the flow diagram of FIG. 2, at step 502 of FIG. 5, the charging cycle can begin, for example subsequent to the evacuation cycle, by opening valve 404 to allow the refrigerant in the storage tank 212, which is at a pressure of approximately 70 psi or above, to flow through open high side charge valve 298 and fill the service hose up to the hose fill valve 401. In addition, at step 502, optionally low side charge valve 299 can also be opened to fill the low side service hose up to hose fill valve 402.

[0063] At step 503, at time delay function can take place to allow one or both of the service hoses 124, 128 to fill up with refrigerant. The time delay function may be, for example, about a 2 second time delay function to allow refrigerant to flow into the service hoses 124, 128 and a portion of the a fill recirculating circuit 400 leading up to a recirculating valve 403. Other time delays can include 1, 3, 4, 5, ...etc., seconds delays as predetermined, or in some embodiments, adjusted based on measured sensor data. At step 504, subsequent to filling one or both of the service hoses 124, 128 and the portion of the hose fill recirculating circuit 400 leading up to a recirculating valve 403 with refrigerant, the recirculating valve 403 is opened to recirculate refrigerant from the coupler ends of the high end service hose 124 and the low end service hose 128 to the system oil separator 262, which in some embodiments can preferably be in a vacuum, to allow removing vapor refrigerant contained in the service hoses 124, 128, as shown in the charging circuit 425 in Fig. 2.

[0064] At step 505, a second time delay function can keep the recirculating valve 403 open during the time delay thereby allowing the removal of vapor refrigerant to take place. The second time delay function can be, for example, about a 5 second time delay function during which a significant amount of vapor refrigerant originally contained in the service hoses 124, 128 is replaced with recirculated condensed refrigerant. Other time delays can include 1, 3, 4, 5, ...etc., seconds delays as it may be predetermined or in some embodiments adjusted based on sensor data. Removal of vapor refrigerant is desired since the ratio between vapor refrigerant and liquid refrigerant contained prior to the recirculating can vary based in factors such as ambient temperature. In some embodiments, the amount of liquid refrigerant contained in both service hoses 124, 128 can account, for example, anywhere from about 183.00 grams when it is mostly liquid refrigerant to about 6.00 grams when it is mostly vapor refrigerant. Consequently, it is important to know the actual weight of the refrigerant contained in the service hoses 124, 128 and compensate for it in the reference weight of a refrigerant container, or to eliminate the variable, to improve charge accuracy of the refrigerant recovery unit 100.

[0065] The recirculating circuit 400 may be a flexible hose or any other suitable conduit for providing fluid communication, and forming a flow path loop between the end of one or both the coupler 226 end of the high end service hose 124 and the coupler 230 end of the low end service hose 128 to a part of the system capable of removing vapor refrigerant, such as the system oil separator 262. Generally, the recirculating circuit 400 can be a parallel refrigerant conduit for each, or both, service hoses 124, 128, connected near or at the hose couplers 226, 230. In some embodiments, the parallel refrigerant conduit(s) may be contained in a conduit hose material enclosing. This may be advantageous, for example, to prevent entanglement of the parallel lines. Valves may be electronically activated solenoid valves controlled by the controller 216. The connections may be a wireless or wired connections. In other embodiments the valves may be manually activated valves that can be actuated by a user.

[0066] Subsequent to the second time delay and as depicted in FIG. 3 the recirculating valve 403 is closed. Following, at step 506, an initial scale weight Wi can be taken by scale 215. Wi can be a reference weight of the storage tank 212 when the charging path and up to the service hoses 124, 128 are filled with liquid refrigerant up to hose fill valves 401, 402. At step 507, in some embodiments, the hose fill valves 401, 402 can be opened to allow the charging of refrigerant to the refrigerant system 200 via the couplers 226 (high side) and 230 (low side), respectively, as shown in the charging circuit 425 in Fig. 3.

[0067] At step 508, at least a second weight measurement W₂ by scale 215 to determine if the change in mass from W₂-W₁ is equal to the target weight of step 509 of the refrigerant required for proper service of the refrigerant system 200. The target weight 509 can be, for example, the refrigerant weight as provided by the system's specifications. When the target change in weight is less than desired, more refrigerant can be added to the system and another weight can be taken until the target change is met. Once the proper amount of refrigerant has been added to the refrigeration system, at step 510, the charge and hose fill solenoids can be closed to complete the charging.

[0068] Referring now to FIG. 4, another exemplary alternative embodiment according to aspects of the disclosure is depicted. In particular, the exemplary embodiment includes different flow path conduits for the charging circuit 425 and for the hose fill recirculation circuit 400. In some embodiments, a t-fitting near the couplers 223, 230, or alternatively that is part of the couplers, can be used to split the hose fill recirculating circuit 400 and the charging circuit 425. This can allow for a common connection to the refrigerant system 200 but yet minimizing the sharing of the fluid paths. In a similar manner, however, the parallel refrigerant conduit(s) may be contained in a single conduit hose material enclosing. This may be advantageous, for example, to prevent entanglement of the parallel lines.

[0069] By keeping different flow path conduits, the service hoses 124, 128 can remain full of liquid refrigerant to significantly improve the charging accuracy of the refrigerant recovery unit 100. In the same manner described, however, the method steps 500 can be performed in this type of refrigerant recovery unit 100 for calibration when refrigerant is first added and/or every so often depending on the type of refrigerant system 200 being serviced. In addition, the diameter of the charging flow path 425 can be reduced thereby reducing refrigerant amount variation and improving flow consistency. Further, contamination of the refrigerant being charged is prevented since any remaining matter in the recovery circuit 275 is significantly decreased due to the limited shared fluid path.

[0070] In some embodiments, aspects of the refrigerant recovery unit 100 may be implemented via the controller 216 forming part of a control system (not shown) that is capable of implementing software or a combination of software and hardware. Control system may be integrated with the controller 216 to permit, for example, automation of the recovery, evacuation, and recharging processes and/or manual control over one or more of each of the processes individually. In one embodiment, the control system can allow the refrigerant recovery unit 100 to communicate and diagnose the refrigeration system being serviced.

[0071] In another embodiment, the control system can allow for communication with a diagnostic tool, such as a VCI, that is coupled to the refrigeration system under service. This allows the refrigerant recovery unit 100 to receive data which could include Heating, Ventilation and Air Conditioning ("HVAC") systems sensor readings, related diagnostic trouble codes, system pressures, and interactive tests, like actuating of various components, such as a fan control. All of this data and information would be displayed on the display 110 of the refrigerant recovery unit 100. Menu selections, diagnostic trouble codes, and interactive tests may be displayed and certain diagnostic may be performed using the refrigerant recovery unit 100.

[0072] The control system may include a processor connected to a communication infrastructure (e.g., a communications bus, cross-over bar, or network). The various software and hardware features described herein are described in terms of an exemplary control system. A person skilled in the relevant art(s) will realize that other computer related systems and/or architectures may be used to implement the aspects of the disclosed disclosure. [0073] Referring now to FIG. 6 components included within and/or that may be included in refrigerant recovery units are depicted in a flow diagram according to aspects of the disclosure. In the following section, general functionality of the refrigerant recovery unit 100 and components therein are described.

[0074] In some embodiments, to service the refrigerant system 200a, the service hoses 124a, 128a can be coupled to the refrigerant system 200a, via couplers 226a (high side) and 230a (low side), respectively. The couplers 226a, 230a can be designed to be closed until they are coupled to the refrigerant system 200a.

Recovery Cycle

[0075] The recovery cycle can be initiated by the opening of high pressure and low- pressure solenoids 276a, 278a, respectively. This allows the refrigerant within the refrigerant system 200a to flow through a recovery valve 280a and a check valve 282a. The refrigerant flows from the check valve 282a into a system oil separator 262a, where it travels through a filter/dryer 264a, to an input of a compressor 256a. Refrigerant is drawn through the compressor 256a through a normal discharge solenoid 284a and through a compressor oil separator 286a, which circulates oil back to the compressor 256a through an oil return valve 288a. The refrigerant recovery unit 100 may include a high-pressure switch 290a in communication with a controller 216a, which can be programmed to determine an upper pressure limit, for example, about 435 psi, to optionally shut down the compressor 256a to protect the compressor 256a from excessive pressure.

[0076] The controller 216a can also be, for example, a microprocessor, a field programmable gate array (FPGA) or application-specific integrated circuit (ASIC). The controller 216a via a wired or wireless connection (not shown) controls the various valves and other components (e.g. vacuum pump 258a, compressor 256a) of the refrigerant recovery unit 100. In some embodiments of the present disclosure, any or all of the electronic solenoid or electrically activated valves may be connected and controlled by the controller 216a.

[0077] A high-side clear solenoid 323a may optionally be coupled to the output of the compressor 256a to release the recovered refrigerant transferred from the compressor 256a to a path conduit leading into a refrigerant storage tank 212a, instead of through a path conduit through the normal discharge solenoid 284a.

[0078] A deep recovery valve 252a is provided to assist in the deep recovery of refrigerant. When the refrigerant from the refrigerant system 200a has, for the most part, entered into the refrigerant recovery unit 100, the remaining refrigerant may be extracted from the refrigerant system 200a through a deep recovery circuit 250a by opening the deep recovery valve 252a and turning on the vacuum pump 258a. Additionally, the high pressure switch 289a can be included to shut off the vacuum pump 258a when pressure in the deep recovery circuit 250a increases above a pre-determined level.

[0079] The heated compressed refrigerant can exit the system oil separator 262a and travel through a loop of conduit or heat exchanger 291a for cooling or condensing. As the heated refrigerant flows through the heat exchanger 291a, the heated refrigerant gives off heat to the cold refrigerant in the system oil separator 262a, and assists in maintaining the temperature in the system oil separator 262a within a working range. Coupled to the system oil separator 262a can be a switch or transducer 292a, such as a low pressure switch or pressure transducer 310a, for example, that senses pressure information, and provides an output signal to the controller 216a through a suitable interface circuit programmed to detect when the pressure of the recovered refrigerant is down to 13 inches of mercury, for example. An oil separator drain valve 293a can drain the recovered oil into a container 257a. Finally, the recovered refrigerant can flow through a normal discharge check valve 294a along a refrigerant circuit 322a and, in some embodiments, through a vapor check valve 325a into the refrigerant storage tank 212a.

Evacuation Cycle

[0080] The evacuation cycle can begin by the opening of the high pressure and low- pressure solenoids 276a, 278a and a valve 296a, leading to the input of a vacuum pump 258a. Prior to opening the valve 296a, an air intake valve (not shown) is opened, allowing the vacuum pump 258a to start exhausting air. The refrigerant of the refrigerant system 200a can then be evacuated by the closing of the air intake valve (not shown) and opening the valve 296a, allowing the vacuum pump 258a to exhaust any trace gases remaining until the pressure is approximately 29 inches of mercury, for example. When this occurs, as detected by pressure transducers 231a, 232a, optionally, coupled to the high side coupler 226a and low side coupler 230a of the refrigerant system 200a and to the controller 216a, the controller 216a may turn off the valve 296a allowing for the charging cycle to take place.

[0081] In embodiments where at least a portion of the recovery path conduit is shared with the flow path conduit leading to the oil separator for the charging process, as depicted, hose fill valves 401a, 402a can remain open during the evacuation process. In other embodiments where there are separate paths for the evacuation and charging, the hose fill valves 401a, 402a will preferably remain closed during the evacuation cycle to prevent oil contamination from the evacuated refrigerant.

Air Purging

[0082] An air purging apparatus 308a is also illustrated. The air purging apparatus 308a allows the refrigerant recovery unit 100 to be purged of non-condensable, such as air. Air purged from the refrigerant recovery unit 100 may exit the refrigerant storage tank 212a, through an orifice 312a, through a purging valve 314a and through an air diffuser 316a. In some embodiments, the orifice 312a may be about 0.028 of an inch. A pressure transducer 310a can be used to measure the pressure contained within the refrigerant storage tank 212a and the air purging apparatus 308 accordingly. For example, the pressure transducer 310a may send the pressure information to the controller 216a, and when the pressure is too high, as calculated by the controller 216a, purging is required. In addition or alternatively, a high pressure relief 31 1a may be included to shut off the system when pressure increases above a pre-determined level.

[0083] The purging valve 314a may be selectively actuated to permit or not permit the air purging apparatus 308a to be open to the ambient conditions. A temperature sensor 317a may be coupled to the refrigerant storage tank 212a to measure the refrigerant temperature therein. The placement of the temperature sensor 317a may be anywhere on the refrigerant storage tank 212a or alternatively, the temperature sensor 317a may be placed within the refrigerant circuit 322a. The measured temperature and pressure may be used to calculate the ideal vapor pressure for the type of refrigerant used in the refrigerant recovery unit 100. The ideal vapor pressure can be used to determine when the non-condensable gases need to be purged and how much purging will be done in order for the refrigerant recovery unit 100 to function properly.

Charging Cycle

[0084] For purposes of clarity and in accordance to aspects of the disclosure, the charging cycle is explained in reference to method steps 600 of FIG. 10 along with the flow diagram illustrated in FIG. 6. FIG. 10 is a flowchart illustrating method steps 600 to charge a refrigerant system 200a according to aspects of the disclosure. In particular, the method steps 600 can be used to charge the refrigerant system 200a with increased accuracy by thermally conditioning the interior of one or both service hose(s) 124a, 128a to a constant temperature before refrigerant is transferred. The temperature conditioning can be achieved using methods including, for example, by recirculating refrigerant and/or using a resistance heater 315a (shown in FIG. 8) along the length of the service hoses 124a, 128a.

[0085] At step 601, the service hoses 124a, 128a can be coupled to the refrigerant system 200a, via the couplers 226a (high side) and 230a (low side), respectively. In some embodiments, as depicted in the flow diagram of FIG. 6, at step 605 of FIG. 10, the charging cycle can begin, for example subsequent to the evacuation cycle, by opening valve 404a to allow the refrigerant in the refrigerant storage tank 212a, which is at a pressure of approximately 70 psi or above, to flow through open high side charge valve 298a and fill the service hose up to the hose fill valve(s) 401a. In addition, at step 605, optionally low side charge valve 299a can also be opened to fill the low side service hose up to hose fill valve(s) 402a. In another embodiment, in order to charge the refrigerant system 200a, the power charge valve 326a may be opened and a tank fill structure (not shown) may be used. Alternatively or in addition to, the tank fill structure (not shown) may also be used to fill the refrigerant storage tank 212a.

[0086] At step 610, at time delay function can take place to allow one or both of the service hoses 124a, 128a to fill up with refrigerant. The time delay function may be, for example, about a 2 second time delay function to allow refrigerant to flow into the service hoses 124a, 128a and a portion of the recirculating circuit 400a leading up to a recirculating valve 403a. Other time delays can include 1, 3, 4, 5, ...etc., seconds delays as predetermined, or in some embodiments, adjusted based on measured sensor data. At step 615, subsequent to filling one or both of the service hoses 124a, 128a and the portion of the recirculating circuit 400a leading up to a recirculating valve 403 a with refrigerant, the recirculating valve 403 a is opened to recirculate refrigerant from the coupler ends of the high end service hose 124a and the low end service hose 128a to the system oil separator 262a, which in some embodiments can preferably be in a vacuum, to allow removing of vapor refrigerant contained in the service hoses 124a, 128a and thermally condition the service hoses 124a, 128a to an acceptable charging temperature throughout their length.

[0087] In some embodiments, at step 620, a second time delay function can keep the recirculating valve 403 a open during the time delay thereby allowing refrigerant to recirculate from the distal end of the service hoses 124a, 126a in relation to the refrigerant recovery unit 100, to thermally condition them and/or remove vapor refrigerant. The second time delay function can be, for example, about a 5 second time delay function during which a significant amount of vapor refrigerant originally contained in the service hoses 124a, 128a is replaced with recirculated condensed refrigerant. Other time delays can include 3, 4, 6, 7, 8... etc., seconds delays as it may be predetermined or in some embodiments adjusted based on sensor data. For example, in some embodiments, at step 621, one or more temperature sensor 317da can be located anywhere along the length or near the service hoses 124a, 128a to measure the ambient temperature or internal temperature.

[0088] Removal of vapor refrigerant and constant temperature in the service hoses 124a, 128a are desired since the ratio between vapor refrigerant and liquid refrigerant contained prior to the recirculating and temperature conditioning can vary causing inaccurate charging. For example, in some embodiments, the amount of liquid refrigerant contained in both service hoses 124a, 128a can account, for example, anywhere from about 183.00 grams when it is mostly liquid refrigerant to about 6.00 grams when it is mostly vapor refrigerant. Consequently, it is important to know the actual weight of the refrigerant contained in the service hoses 124a, 128a, whether any will remain due to temperature differentials, and compensate for it in the reference weight of a refrigerant storage tank 212a, or to eliminate the variables, to improve charge accuracy of the refrigerant recovery unit 100. Accordingly, in some embodiments one or both said first and second time delay functions can last longer periods of time to thereby allow the thermal conditioning of one or both service hose(s) 124a, 128a to occur through the recirculation of refrigerant. In addition, the length of time of each time delay may be predetermined depending on the application, based on sensor readings of ambient surrounding conditions as previously mentioned, and/or, type of refrigerant, service hose(s) 124a, 128a compositions, insulation materials, internal surface characteristics, refrigerant type, charging conditions, and the like.

[0089] The recirculating circuit 400a may be a flexible hose or any other suitable conduit for providing fluid communication, and forming a flow path loop between the refrigerant system 200a coupler 226a, 230a ends of one or both of the high end service hose 124a and the low end service hose 128a to a part of the system capable of removing vapor refrigerant, such as the system oil separator 262a. Generally, the recirculating circuit 400a can be a parallel refrigerant conduit for each, or both, service hoses 124a, 128a, connected near or at the hose couplers 226a, 230a. In some embodiments, the parallel refrigerant conduit(s) may be contained in a conduit hose material enclosing. This may be advantageous, for example, to prevent entanglement of the parallel lines. Valves may be electronically activated solenoid valves controlled by the controller 216a. The connections may be a wireless or wired connections. In other embodiments the valves may be manual user activated valves.

[0090] At step 622, in some embodiments alternatively or in addition to the recirculating of refrigerant, the resistance heater 315a (shown in FIG. 8) along the length of the service hoses 124a, 128a can be activated, according to a measured temperature or preprogrammed function, to provide a constant temperature along the interior surfaces of the service hoses 124a, 128a, for example, before the transfer of refrigerant begins and/or according the one or more temperature readings at step 621.

[0091] Subsequent to the second time delay, at step 620, the recirculating valve 403a is closed. Following, at step 625, an initial scale weight Wi can be taken by scale 215a. Wi can be a reference weight of the refrigerant storage tank 212a when the charging path including the service hoses 124a, 128a up to hose fill valves 401a, 402a are filled with liquid refrigerant. At step 630, in some embodiments, the hose fill valves 401a, 402a can be opened to allow the charging of refrigerant to the refrigerant system 200a via the couplers 226a (high side) and 230a (low side), respectively.

[0092] At step 635, at least a second weight measurement W2 by scale 215a is taken to determine if the change in mass from W₂-W₁ is equal to the target weight at step 640 of the refrigerant required for proper service of the refrigerant system 200a. The target weight at step 640 can be, for example, the refrigerant weight as provided by the system's specifications. When the target change in weight is less than desired, more refrigerant can be added to the system and another weight can be taken until the target weight is met. Once the proper amount of refrigerant has been added to the refrigerant system 200a, at step 645, the charge and hose fill solenoids can be closed to complete the charging.

[0093] Referring now to FIG. 7, the refrigerant recovery unit 100 connected to a refrigerant system 200a of a vehicle and an enlarged cross section of an exemplary temperature controlled service hose 124a, 128a are depicted. In particular, the refrigerant stored in the refrigerant storage tank 212a can be charged with increased accuracy into the refrigerant system 200a using thermally controlled service hose(s) 124a, 128a. No limitations are placed on the kind of refrigerant that may be used according to the present disclosure. As such, any refrigerant that is commonly available (e.g., R-134a, CO2, R1234yf, etc.) may be stored within the refrigerant storage tank 212a. However, according to certain embodiments of the present disclosure, the refrigerant storage tank 212a can be particularly configured to accommodate refrigerants that are commonly used in refrigeration systems 200a, such as air conditioning systems.

[0094] A refrigerant system 200a can be charged using service hose(s) 124a, 128a which are configured to facilitate transfer of the refrigerant from the refrigerant storage tank 212a to the refrigerant system 200a. The service hose(s) 124a, 128a may include and/or be extended by one or more hoses (not shown). According to aspects of the present disclosure, one or both service hoses 124a, 126a can include a resistance heater 715 along the length of the service hoses 124a, 128a. The resistance heater 715 can be flexible and include, and/or, be capable of conducting heat to heat conductors 710 that can conduct and spread heat around the internal walls of the service hoses 124a, 128a.

[0095] Heat conductors 710 may be arranged in ring patterns, spiral patterns, and/or grid patterns, along the length of the service hoses 124a, 128a. Alternatively, the internal walls of the service hoses 124a, 128a may include a conductive flexible material or heat absorbing material including, for example, stainless steel, synthetic heat preservation rubber, polyethylene, and known service hose materials of the like. Other types of heaters and/or methods of controlling the internal temperature of the service hoses 124a, 128a to increase the charge accuracy of a refrigerant recovery unit 100 are within the scope of the disclosure. For example, as disclosed herein, using a recirculating circuit 400a to thermally condition the service hoses 124a, 128a through the flow of refrigerant along the length of the service hoses 124a, 128a prior to charging. In some embodiments, both a recirculating circuit 400a and a resistance heater 315a can be included in the refrigerant recovery unit 100.

[0096] In some embodiments, an insulating material 305 a can be included along the length of the service hoses 124a, 128a to allow handling of the service hoses 124a, 128a. Insulating material 305a can include a rubber, foam, polymer, and other known insulating materials of the like. Insulating material 305a can further include a coating layer 301a used for protection of the service hoses 124a, 128a. One or both of the insulating material 305a and the coating later 301a can protect the hose, internal components, and a user from electric shock and burning temperatures when handling the service hoses 124a, 128a. The coating 301a composition and the insulating 305a composition can include the same materials or different depending on the embodiment.

[0097] Referring now to FIG. 8, a schematic diagram showing additional components that can be included within and/or that may be connected to the refrigerant system 200a is illustrated. In particular, FIG. 8 illustrates that the controller 216a can include an internal memory 410a, a processor 420a and a communications port 415a. The representative communications port 415a can also be connected to an external memory 425a, a display 110a, an input/output (I/O) device 430a, a network 435 a, the one or more temperature/pressure sensor(s) 317aa-da that can monitor the temperature and/or pressure in the refrigerant storage tank 212a, the service hoses 124a, 128a and external ambient temperatures and pressures.

[0098] According to aspects of the present disclosure, the one or more temperature/pressure sensor(s) 317aa-da can be configured to determine and/or sense a temperature/pressure within the refrigerant storage tank 212a, ambient temperature, and/or inside one or both service hose(s) 124a, 126a. For example, temperature sensor 317aa may be placed, on the outside of the refrigerant storage tank 212a or inside of the refrigerant storage tank 212a. Further, depending on the type of temperature sensor(s) 317aa-da used or as desired by the user, the temperature sensor 317aa may be placed on an upper, middle or lower portion of the refrigerant storage tank 212a. In another embodiment, temperature sensor 317ba may be placed at or near the point where the refrigerant exits the refrigerant storage tank 212a. In still another embodiment, temperature sensor 317da may be placed in or outside one or both service hose(s) 124a, 128a. In a further embodiment, the temperature sensor 317da may also be placed anywhere among the components (hoses, fittings, valves, etc.) that are between the refrigerant storage tank 212a and the refrigerant system 200a being charged with refrigerant.

[0099] In another embodiment, a temperature sensor 317ca may be placed on an outside surface of a housing 102a of the refrigerant recovery unit 100. In a further embodiment, the temperature sensor 317ca may be placed within the housing 102a. The placement of temperature sensor 317ca can be anywhere on or in the housing 102a so long it can measure the surrounding ambient temperature.

[0100] In addition, the controller 216a can be included in the refrigerant recovery unit 100 and in connection with components including, for example, the temperature sensor(s) 317aa-da, the service hose(s)' heater 315a, and recirculating valves 440a to regulate and/or compensate for temperature differentials and increase change accuracy according to aspects of the disclosure. For example, the one or more temperature sensor(s) 317aa-da may transmit the sensed temperature via a wired or wireless connection. The sensed temperature may be transmitted when requested by the controller 216a, for example, prior to initiating the charge cycle and/or during refrigerant recirculation, or pushed all the time or on a predetermined basis, such as every 30 seconds, minute, 5 minutes, 15 minutes, 30 minutes, hour, etc..

[0101] Also illustrated are valves 440a (e.g., solenoid valves described in FIG. 2) that, according to certain embodiments, can either be included within or in fluid connection to the service hose(s) 124a, 126a. When the refrigerant recovery unit 100 is in operation, the valves 440 may be opened and shut by the controller 216a based on programed steps and functions including, for example, the steps discussed in this disclosure. For example, the controller 216a, can be configured to control the service hose connections couplers 226a, 230a to thereby control how much refrigerant flows from the refrigerant storage tank 212a to the refrigerant system 2

[0102] In addition, the controller 216a can also be configured to determine a compensated amount of refrigerant to be added to the refrigerant system 200a. Such a determination may be made, for example, based upon the refrigerant temperature obtained from within the refrigerant storage tank 212a and refrigerant system 200a, the temperature obtained inside or on one or both service hose(s) 124a, 128a, and/or the ambient surrounding temperature.

[0103] Either or both of the memories 410a, 425a may be configured to store one or more formulas and one or more measured temperatures and/or system condition thresholds that can be used to calculate the amount of compensated refrigerant that should be added to a refrigerant system 200a based upon relative temperature measured at the refrigerant storage tank 212a and the refrigerant system 200a. For example, when a vehicle's refrigerant system 200a is one included in an automobile, one or more of the temperature sensor 317a may be connected to or may be a part of the automobile's on-board diagnostic (OBD) system (not shown). In such instances, the communications port 415a of the controller 216a may receive temperature information from the OBD system using a data link connector (not shown) connected via the communications port 415a.

[0104] Also, a refrigerant recovery unit's manufacturer may publish empirical data in a similar format for a variety of refrigerant systems and/or refrigerants and/or environmental conditions. Then, information about one or more of the optimal amounts can be, for example, downloaded to the internal memory 410a of the controller 216a from the network 435 a, which may be an intranet, the Internet, LAN, WAN, or some other electronic network. As an alternative, information from a disc or other electronic network may be transferred directly to the controller 216a when the I/O device 430a takes the form of a CD or DVD reader/writer, or USB connector. Once a sufficient amount of information has been imported, the refrigerant recovery unit 100 may be used to charge or recharge the refrigerant system 200a.

[0105] Referring now to FIG. 9, a flowchart illustrating method steps 500 to charge refrigerant into a refrigerant system 200a according to aspects of the disclosure is depicted. The method can start at step 501 with the identification of the refrigerant system 200a to be charged. The identification may include, in some embodiments, identifying the type of refrigerant, amount of refrigerant, recommended charging temperatures and conditions, and the such, as per manufacturer's specifications. The refrigerant system 200a can be, for example, the A/C system in a vehicle and the user can select the make and model of vehicle from a list presented on the display 1 10 of the refrigerant recovery unit 100. Alternatively, the user can enter the vehicle make and model (or VIN) using the key pad. Other types of A/C systems are also within the scope of the present disclosure, including those in residential or commercial buildings, planes, farm machinery, etc..

[0106] At step 505, one or more temperature readings can be taken. Temperature reading(s) can include, for example, measuring a first temperature of the refrigerant storage tank 212a using temperature sensor 317aa and a second temperature sensor 317da within the service hoses 124a, 128a. Since the temperature sensor 317ca may be part of a vehicle's larger system (e.g., an automobile's OBD system), according to certain embodiments of the present disclosure, step 505 may include obtaining the second temperature from a computer that is at least partially controlling a portion of the refrigerant system 200a.

[0107] At step 515, the interior temperature of one or both service hose(s) 124a, 128a can be adjusted to eliminate temperature differentials along the length of the service hose(s) 124a, 128a and/or between one or more of the refrigerant storage tank 212a, ambient conditions, and the refrigerant system 200. Adjustment of the temperature can include, for example, the methods described in this disclosure to heat/align the internal temperature of the service hoses 124a, 128a. Other methods/systems can include, for example, a parallel flow of heated liquid flowing around the external boundaries containing the refrigerant. By reducing the temperature differential between the refrigerant storage tank 212a and inside the service hoses 124a, 128a, a more accurate amount of refrigerant may be added to refrigerant systems 200a. Thus, amounts of refrigerant that may have remained trapped in service hoses 124a, 128a or fittings during a charge may be eliminated or significantly reduced to increase charge accuracy, thereby increasing refrigerant system's 200a performance.

[0108] Moreover, in some embodiments at step 520, temperature measurements may be taken throughout the charging of refrigerant continuously and/or at a predetermined frequency to monitor conditions and alert the user and/or stop the charging upon sensing a condition differential that is above or below a predetermined threshold. This function may not only increase charge accuracy but also act as a safety check for the refrigerant recovery unit 100. Finally, when measured conditions are at an acceptable level, at step 525, the refrigerant system 200 is charged with the determined amount of refrigerant with greater accuracy and more safely.110

[0109] As shown in FIG. 11, a refrigerant recovery system 10b includes a pair of hoses 12b and 14b. One or both of the pair of service hoses 12b and 14b includes a service coupler 16b, check valve assembly 18b, and hose 20b. The service coupler 16b is configured to mate with a port or coupler of a refrigeration system such as the refrigeration system 200b shown in FIG. 17. In various embodiments, the refrigeration system may include any suitable device, unit, or system having a supply of refrigerant therein. Examples of suitable refrigeration systems include a standalone air conditioning or de-humidifying unit and/or a unit disposed within a vehicle, device, appliance, structure, or the like. A vehicle can be any suitable vehicle, such as an automobile, train, airplane, boat, ship and the like. Suitable devices or appliances may include, for example, an air conditioning unit, dehumidifier, ice maker, refrigerator/freezer, beverage dispenser, ice cream maker, and the like.

[0110] The check valve assembly 18b is configured to provide substantially unrestricted unidirectional flow of refrigerant during recovery operations and to provide a predetermined cracking pressure during recharging operations. The predetermined cracking pressure is determined based upon a variety of factors. These factors include: refrigerant type and/or chemistry; refrigerant manufacturer's recommendations; expected operating conditions including ambient temperature and pressure; empirical data; and the like.

[0111] The hose 20b is configured to convey refrigerant through the service hose 12b/14b. As is generally known, the hose 20b has a nominal inside diameter and a length. Given the nominal inside diameter and a length, an interior volume of the hose 20b is readily determinable. For example, given a nominal inside diameter of 5 millimeters (mm) and a length of 2 meters (m), the interior volume of the hose 20b is 100 milliliters (ml). A common automotive refrigerant is R-134a (1, 1, 1, 2-Tetrafluorethane) which has a liquid density of 1206 of kilograms/m³ or 1.206 grams(g)/ml and gas density of 4.25 kg/m³ or 4.25 milligrams (mg)/ml at 1.013 bar and 15°C. As such, the hose 20b may retain about 120.6 g of liquid refrigerant vs. 0.425 g of gaseous refrigerant at standard atmospheric conditions. Unfortunately, the conditions within the hose 20b may be difficult to determine given the potential variability in ambient conditions and rapid increases and decreases in pressure during recovery and recharging operations. As such, the weight of gaseous refrigerant in the hose 20b may vary from nearly 120 g to essentially 0 g (given a partial vacuum and temperatures of 40°C or more). However, the weight of liquid refrigerant will always be substantially 120.6g for the hose 20b having an interior volume of 100 ml and given the refrigerant is R-134a. For the purposes of this disclosure, the term "substantially" and "essentially" refers to a generally understood variance of about l%-5%. Factors that may cause this variance include wear on the hose 20, excessive pressure within the hose 20b, contaminants within the refrigerant that have different densities or other properties, and the like.

[0112] The refrigerant recovery unit 100 can be the AC1234™ from ROBINAIR® based in Owatonna, MN (Service Solutions U.S., LLC). The refrigerant recovery unit 100b includes a cabinet 102b to house components of the system (See FIG. 17). The cabinet 102b may be made of any suitable material such as thermoplastic, steel and the like. [0113] The cabinet 102b includes a control panel 104 that allows the user to operate the refrigerant recovery unit 100b. The control panel 104b may be part of the cabinet as shown in FIG. 11 or separated. The control panel 104b includes high and low gauges 106b, 108b, respectively. For the purposes of this disclosure, the terms, "high" and "low" generally refer to the high and low pressure sides of a refrigeration system, respectively. The gauges may be analog or digital. The control panel 104b has a display 110b to provide information to a user. The information may include, for example, operating status of the refrigerant recovery unit 100b or provide messages or menus to the user. The control panel 104b may include indicators 112b to indicate to the user the operational status of the refrigerant recovery unit 100b. If included, the indicators 112b may include light emitting diodes (LEDs) or the like, that when activated, may indicate that the refrigerant recovery unit 100b is in the recovery, recycling or recharging mode or indicate that the filter needs to be changed or that there is a malfunction.

[0114] According to an embodiment, the control panel 104b includes a user interface 114b to provide the user with an interface to interact and operate the refrigerant recovery unit 100b. The user interface 1 14b may include any suitable interface such as, for example, an alphanumeric keypad, directional arrows, function keys, pressure or touch sensitive display, and the like. Optionally, a printer 1 16b is provided to print out information, such as test results.

[0115] The cabinet 102b further includes a plurality attachment points 124b, 128b for the service hoses 12b, 14b that connect the refrigerant recovery unit 100b to a refrigerant containing device, such as a refrigeration system (shown in FIG. 17). Also shown in FIG. 11, a vehicle connector interface 130b is provided so that a communication cable can be connected from the vehicle connector interface to a data link connector in a vehicle (not shown in FIG. 1 1). This allows the refrigerant recovery unit 100 to communicate with the vehicle and diagnose any issues with it. In order for the refrigerant recovery unit 100b to be mobile, one or more wheels 120b are provided at a bottom portion of the cabinet 102b.

[0116] During servicing of a refrigeration system (shown in FIG. 17), if it is determined that the refrigerant therein should be recovered and then recharged, the refrigerant recovery unit 100b may be connected to the refrigeration system via the service hoses 12b and 14b. More particularly, the respective service coupler 16b of each of the service hoses 12b and 14b is used to fluidly connect the refrigeration system to the refrigerant recovery unit 100b. For example, the refrigerant may be conveyed through the service hoses 12b and 14b in response to the refrigeration system being connected to the refrigerant recovery unit 100b.

[0117] FIG. 12 is a perspective view of the service hose 12b in accordance with the embodiment of FIG. 11. Of note, while particular reference is made of the service hose 12b, the service hose 14b and the components of the service hose 14b are similar to the description of the service hose 12b. As shown in FIG. 12, the service hose 12b includes the service coupler 16b, the check valve assembly 18b, the hose 20b, and the attachment point 124b. As described herein, the service coupler 16b is configured to mate with a refrigeration system. The check valve assembly 18b is disposed proximal to the service coupler 16b to minimize volume in the service hose 12b that is not subject to the cracking pressure supplied by the check valve assembly 18b. The hose 20b is configured to convey the refrigerant therethrough and to have a known internal volume. The attachment point 124b is configured to fluidly connect the service hose 12b to the refrigerant recovery unit 100b. Like the service coupler 16b, the attachment point 124b is configured to seal the service hose 12b when not connected. In this manner, refrigerant leakage into the environment may be minimized or reduced.

[0118] FIG. 13 is cut away view of the parallel flow check valve assembly 18 in an idle conformation in accordance with the embodiment of FIG. 1 1. As shown in FIG. 13, the check valve assembly 18b includes a recovery flow path 22b and a recharge flow path 24b. The recovery flow path 22b includes a recovery poppet 26b, an O-ring 28b, and a stand-off 30b. The recharge flow path 24b includes a recharge poppet 32b, an O-ring 34b, a spring 36b, and a shim 38b. The various components of the check valve assembly 18b are disposed in a body 40b. The recovery flow path 22b is defined by a first bore disposed in the body 40b, the recovery poppet 26b, the O-ring 28b, and the stand-off 30b. The recharge flow path 24b is defined by a second bore disposed in the body 40b, the recharge poppet 32b, the O- ring 34b, the spring 36b, and the shim 38b. As shown in FIG. 13, both flow paths 22b and 24b are sealed. That is, the recovery poppet 26b is sealed against the O-ring 28b and the recharge poppet 32b is sealed against the O-ring 34b. However, as discussed herein, the recovery poppet 26b is not biased toward an open or closed position and thus, without backpressure on the recovery poppet 26b, flow in the direction of the recovery flow path 22b is configured to open the seal between the recovery poppet 26b and the O-ring 28b. In contrast, the spring 36b is configured to bias the recharge poppet 32b against the O-ring 34b sufficiently to provide the predetermined cracking pressure. While the spring 36b is shown in FIG. 13, any suitable biasing member may be utilized to bias the recharge poppet 32b against the O-ring 34b. Examples of suitable biasing members include other springs, Belleville washers, pneumatic cylinders and actuators, electronic actuators, and the like.

[0119] FIG. 14 is cut away view of the parallel flow check valve assembly 18 in a recovery conformation in accordance with the embodiment of FIG. 11. As shown in FIG. 14, flow along the recovery flow path 22b is open to the flow of refrigerant. More particularly, the flow of refrigerant along the recovery flow path 22b, has broken the seal between the recovery poppet 26b and the O-ring 28b and driven the recovery poppet 26b against the stand-off 30b. The stand-off 30b includes a central post to prevent the recovery poppet 26b from blocking the outflow of refrigerant. As described herein, the recovery conformation facilitates efficient recovery of refrigerant from a refrigeration system such as the refrigeration system 200b shown in FIG. 17.

[0120] FIG. 15 is cut away view of the parallel flow check valve assembly 18b in a charging conformation in accordance with the embodiment of FIG. 11. As shown in FIG. 15, flow along the recharge flow path 24b is open to the flow of refrigerant. More particularly, the flow of refrigerant along the recharge flow path 24b is of sufficient force to overcome the predetermined cracking pressure provided by the spring 36b. As a result, the seal between the recharge poppet 32b and the O-ring 34b is broken and is configured to remain open to the flow of refrigerant as long as the force of the flow exceeds the predetermined cracking pressure. By maintaining the pressure of the refrigerant upstream of the recharge poppet 32b above the predetermined cracking pressure, the refrigerant upstream of the recharge poppet 32b is maintained in the liquid state. As described herein, calculating the weight of refrigerant is easier and more accurate if the refrigerant is known to be in the liquid state. In this manner, the recharge conformation facilitates improved accuracy of recharging a refrigeration system such as the refrigeration system 200b shown in FIG. 17.

[0121] FIG. 16 is a perspective view of components suitable for use in the parallel flow check valve assembly 18b according to FIGS. 13-15. As shown in FIG. 16, the recovery poppet 26b includes one or more channels 42b to facilitate the flow of refrigerant. The standoff 30b also includes one or more channels 44b to facilitate the flow of refrigerant. Similarly, the recharge poppet 32b includes one or more channels 46b to facilitate the flow of refrigerant.

[0122] FIG. 17 illustrates components of the refrigerant recovery system 10b of FIG. 11 according to an embodiment of the present disclosure. In general, the refrigerant recovery unit 100b is configured to facilitate testing, removing, and recharging refrigerant and/or lubricant in a refrigeration system 200b. More particularly, the refrigerant recovery system 10b is configured to recover the refrigerant quickly and efficiently and the refrigerant recovery system 10b is configured to recharge the refrigeration system 200b accurately. These two processes benefit from different flow characteristics. The service hoses 12b and 14b are configured to provide a first flow characteristic that is conducive to recovery and the service hoses 12b and 14b are configured to provide a second flow characteristic that is conducive to recharging. The first flow characteristic provides minimal inhibition to flow. The second flow characteristic provides a predetermined cracking pressure to maintain the refrigerant in a liquid state.

[0123] In the particular example shown, the refrigerant recovery unit 100b is coupled to the refrigeration system 200b via the service hose 12b (high side) and the service hose 14b (low side). In general, the various hoses and couplers are configured to be closed until they are coupled to the refrigerant recovery unit 100b and/or the refrigeration system 200b. In this manner, refrigerant leakage may be minimized or prevented.

[0124] The recovery cycle is initiated by the opening of high pressure and low- pressure solenoids 276b, 278b, respectively. This allows the refrigerant within the vehicle's refrigeration system 200b to flow through the service hoses 12b and 14b and then through a recovery valve 280b and a check valve 282b. The service hoses 12b and 14b provide minimal restriction to the flow of refrigerant during recovery which allows the refrigerant to boil off and be efficiently drawn from the refrigeration system 200b. To continue, the refrigerant flows from the check valve 282b into a system oil separator 262b, where it travels through a filter/dryer 264b, to an input of a compressor 256b. Refrigerant is drawn through the compressor 256b through a normal discharge valve 284b and through a compressor oil separator 286b, which circulates oil back to the compressor 256b through an oil return valve 288b. The refrigerant recovery unit 100 may include a high-pressure switch 290b in communication with a controller 216b, which is programmed to determine an upper pressure limit, for example, 435 psi, to optionally shut down the compressor 256b to protect the compressor 256b from excessive pressure. The controller 216b can also be, for example, a microprocessor, a field programmable gate array (FPGA) or application-specific integrated circuit (ASIC). The controller 216b via a wired or wireless connection (not shown) controls the various valves and other components (e.g. vacuum, compressor) of the refrigerant recovery unit 100b. In some embodiments of the present disclosure, any or all of the electronic solenoid or electrically activated valves may be connected and controlled by the controller 216b.

[0125] A high-side clear valve 323b may optionally be coupled to the output of the compressor 256b to release the recovered refrigerant transferred from compressor 256b directly into a storage tank 212b, instead of through a path through the normal discharge valve 284b.

[0126] The heated compressed refrigerant exits the oil separator 286b and then travels through a loop of conduit or heat exchanger 291b for cooling or condensing. As the heated refrigerant flows through the heat exchanger 291b, the heated refrigerant gives off heat to the cold refrigerant in the system oil separator 262b, and assists in maintaining the temperature in the system oil separator 262b within a working range. Coupled to the system oil separator 262b is a switch or transducer 292b, such as a low pressure switch or pressure transducer, for example, that senses pressure information, and provides an output signal to the controller 216b through a suitable interface circuit programmed to detect when the pressure of the recovered refrigerant is down to 13 inches of mercury, for example. An oil separator drain valve 293b drains the recovered oil into a container 257b. Finally, the recovered refrigerant flows through a normal discharge check valve 294b and into the storage tank 212b.

[0127] The evacuation cycle begins by the opening of high pressure and low-pressure solenoids 276b and 278b and valve 296b, leading to the input of a vacuum pump 258b. Prior to opening valve 296b, an air intake valve (not shown) is opened, allowing the vacuum pump 258b to start exhausting air. The vehicle's refrigeration system 200b is then evacuated by the closing of the air intake valve and opening the valve 296b, allowing the vacuum pump 258b to exhaust any trace gases remaining until the pressure is approximately 29 inches of mercury, for example. When this occurs, as detected by pressure transducers 231b and 232b, optionally, coupled to the high side 226b and low side 230b of the vehicle's refrigeration system 200b and to the controller 216b, the controller 216b turns off valve 296b and this begins the recharging cycle. Here again, the minimal restriction to flow from the refrigeration system 200b provided by the service hoses 12b and 14b facilitate efficient evacuation of the refrigeration system 200b.

[0128] The recharging cycle begins by opening charge valve 298b to allow the refrigerant in storage tank 212b, which is at a pressure of approximately 70 psi or above, to flow into the service hose 12b. Once sufficient refrigerant pressure has developed within the service hose 12b to overcome the cracking pressure, the refrigerant is allowed to flow through the respective check valve assembly 18b and then through the high side of the vehicle's refrigeration system 200b. The flow is through charge valve 298b for a period of time programmed to provide a full charge of refrigerant to the vehicle. The full charge of the refrigerant is based on the manufacturer's refrigerant amount recommendation plus the weight of refrigerant remaining in the service hose 12b. Because the service hose 12b is configured to maintain the refrigerant in the liquid state and the internal volume of the service hose 12b is known, the weight of refrigerant remaining in the service hose 12b is readily determinable. Optionally, charge valve 299b may be opened to charge the low side. The charge valve 299b may be opened alone or in conjunction with charge valve 298b to supply a flow of refrigerant to the service hose 14b. In a manner similar to the service hose 12b, the service hose 14b is configured to retain the refrigerant until the predetermined cracking pressure is reached before allowing the refrigerant to pass through the respective check valve assembly 18b and then charge the vehicle's refrigeration system 200b. The storage tank 212b may be disposed on a scale (not shown) that measures the weight of the refrigerant in the storage tank.

[0129] Following recharging, any refrigerant remaining in the service hoses 12b and/or 14b may be recovered. For example, the user may be instructed to remove the service couplers 16b from the refrigeration system 200b so that refrigerant is not drawn out of the refrigeration system 200b. Once the service couplers 16b have been removed, a recovery cycle as described herein may be performed to remove any remaining refrigerant in the service hoses 12b and/or 14b.

[0130] Other components shown in FIG. 17 include an oil inject circuit having an oil inject valve 202b and an oil inject hose or line 21 lb. The oil inject hose 21 lb is one example of a fluid transportation means for transmitting oil for the refrigerant recovery unit 100b. The oil inject hose 21 1b may be one length of hose or multiple lengths of hose or tubing or any other suitable means for transporting fluid. The oil inject hose 21 lb connects on one end to an oil inject bottle 214b and on the other end couples to the refrigerant circuit in the refrigerant recovery unit 100b. Disposed along the length of the oil inject hose 21 lb are the oil inject valve 202b and an oil check valve 204b. The oil inject path follows from the oil inject bottle 214, through the oil inject valve 202b, to the junction with the high side charge line, and to the vehicle's refrigeration system 200b.

[0131] FIG. 17 also illustrates a vacuum pump oil drain circuitry 250b that includes a vacuum pump oil drain valve 252b that is located along a vacuum pump oil drain conduit 254b connecting a vacuum pump oil drain outlet 259b to the container 257b for containing the drained vacuum pump oil. The vacuum pump oil drain valve 252b may be an electronically activated solenoid valve controlled by controller 216b. The connection may be a wireless or wired connection. In other embodiments the valve 252b may be a manually activated valve and manually actuated by a user. The conduit 254b may be a flexible hose or any other suitable conduit for provided fluid communication between the outlet 259b and the container 257b.

[0132] FIG. 17 also illustrates an air purging apparatus 308b. The air purging apparatus 308 allows the refrigerant recovery unit 100b to be purged of non-condensable, such as air. Air purged from the refrigerant recovery unit 100b may exit the storage tank 212b, through an orifice 312b, through a purging valve 314b and through an air diffuser 316b. In some embodiments, the orifice may be 0.028 of an inch. A pressure transducer 310b may measure the pressure contained within the storage tank 212b and purge apparatus 308b. The pressure transducer 310 may send the pressure information to the controller 216b. Based upon the pressure information, the controller 216b may initiate purging if it is determined the pressure is too high, as calculated by the controller. The valve 314b may be selectively actuated to permit or not permit the purging apparatus 308b to be open to the ambient conditions. A temperature sensor 317b may be coupled to the main tank to measure the refrigerant temperature therein. The placement of the temperature sensor 317b may be anywhere on the tank or alternatively, the temperature sensor may be placed within a refrigerant line 322b. The measured temperature and pressure may be used to calculate the ideal vapor pressure for the type of refrigerant used in the refrigerant recovery unit. The ideal vapor pressure can be used to determine when the non-condensable gases need to be purged and how much purging will be done in order for the refrigerant recovery unit to function properly.

[0133] High side clearing valves 318b may be used to clear out part of the high- pressure side of the system. The high side clearing valves 318b may include valve 323b and check valve 320b. Valve 323b may be a solenoid valve. When it is desired to clear part of the high side, valve 323b is opened. Operation of the compressor 256b will force refrigerant out of the high pressure side through valves 323b and 320b and into the storage tank 212b. During this procedure the normal discharge valve 284b may be closed.

[0134] A deep recovery valve 324b is provided to assist in the deep recovery of refrigerant. When the refrigerant from the refrigeration system 200b has, for the most part, entered into the refrigerant recovery unit 100b, the remaining refrigerant may be extracted from the refrigeration system 200b by opening the deep recovery valve 324b and turning on the vacuum pump 258b.

[0135] In another embodiment, in order to charge the refrigeration system 200b, the power charge valve 326b may be opened and a tank fill structure 332b may be used. Alternatively or in addition to, the tank fill structure 332b may also be used to fill the storage tank 212b. In order to obtain refrigerant from a refrigerant source, the refrigerant recovery unit 100b may include the tank fill structure 332b, and valves 328b and 330b. The tank fill structure 332b may be configured to attach to a refrigerant source. The valve 330b may be a solenoid valve and the valve 328b may be a check valve. In other embodiments, valve 330b may be a manually operated valve.

[0136] When it is desired to allow refrigerant from a refrigerant source to enter the refrigerant recovery unit 100b, the tank fill structure 332b is attached to the refrigerant source and the tank fill valve 330b is opened. The check valve 328b prevents refrigerant from the refrigerant recovery unit 100b from flowing out of the refrigerant recovery unit 100b through the tank fill structure 332b. When the tank fill structure 332b is not connected to a refrigerant source, the tank fill valve 330b is kept closed. The tank fill valve 330b may be connected to and controlled by the controller 216b.

[0137] The tank fill structure 332b may be configured to be seated on the scale 334b configured to weigh the tank fill structure 332b in order to determine an amount of refrigerant stored in the tank fill structure 332b. The scale 334b may be operatively coupled to the controller 216b and provide a measurement of a weight of the tank fill structure 332b to the controller 216b. The controller 216b may cause a display of the weight of the tank fill structure 332b on the display 110b.

[0138] Aspects of the refrigerant recovery unit 100b may be implemented via control system 400b using software or a combination of software and hardware. In one variation, aspects of the present invention may be directed toward a control system 400b capable of carrying out the functionality described herein. An example of such a control system 400b is shown in FIG. 18. [0139] Control system 400b may be integrated with the controller 216b to permit, for example, automation of the recovery, evacuation, and recharging processes and/or manual control over one or more of each of the processes individually. In one embodiment, the control system 400b allows the refrigerant recovery unit to direct communicate and diagnose the vehicle under service. In another embodiment, the control system 400b allows for communication with a diagnostic tool, such as a vehicle communication interface (VCI), that is coupled to the vehicle under service. It should be understood that the VCI does not have to be coupled to a vehicle in order to communicate with the refrigerant recovery unit 100. This allows the refrigerant recovery unit 100 to receive information from the vehicle such as VIN (vehicle identification number), manufacturer, make, model, and odometer information, and vehicle sensor data that pertains to the heating, ventilation, and air conditioning sensors and systems on the vehicle. Data could include A/C and heating, ventilation, and air conditioning (HVAC) system sensor readings, A/C and HVAC related diagnostic trouble codes, system pressures, and interactive tests, like actuating of various components, such as a fan control. All of this data and information would be displayed on the display 1 10b of the refrigerant recovery unit 100b. Menu selections, diagnostic trouble codes, and interactive tests may be displayed and certain diagnostic may be performed using the refrigerant recovery unit.

[0140] The control system 400b may also provide access to a configurable database of vehicle information so the specifications pertaining to a particular vehicle, for example, may be used to provide exacting control and maintenance of the functions described herein. The control system 400b may include a processor 402b connected to a communication infrastructure 404b (e.g., a communications bus, cross-over bar, or network). The various software and hardware features described herein are described in terms of an exemplary control system. A person skilled in the relevant art(s) will realize that other computer related systems and/or architectures may be used to implement the aspects of the disclosed invention.

[0141] The control system 400b may include a display interface 406 that forwards graphics, text, and other data from memory and/or the user interface 1 14b, for example, via the communication infrastructure 404b for display on the display 1 10b. The communication infrastructure 404b may include, for example, wires for the transfer of electrical, acoustic and/or optical signals between various components of the control system and/or other well- known means for providing communication between the various components of the control system, including wireless means. The control system 400b may include a main memory 408b, preferably random access memory (RAM), and may also include a secondary memory 410b. The secondary memory 410b may include a hard drive 412b or other devices for allowing computer programs including diagnostic database (DTC information and repair and diagnostic information) or other instructions and/or data to be loaded into and/or transferred from the control system 400. Such other devices may include an interface 414b and a removable storage unit 416b, including, for example, a Universal Serial Bus (USB) port and USB storage device, a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an erasable programmable read only memory (EPROM), or programmable read only memory (PROM)) and associated socket, and other removable storage units 416 and interfaces 414b.

[0142] The control system 400b may also include a communications interface 420b for allowing software and data to be transferred between the control system 400b and external devices. Examples of a communication interfaces include a modem, a network interface (such as an Ethernet card), a communications port, wireless transmitter and receiver, Bluetooth, Wi-Fi, infra-red, cellular, satellite, a Personal Computer Memory Card International Association (PCMCIA) slot and card, etc.

[0143] The control system 400b also includes transceivers and signal translators necessary to communicate with the vehicle electronic control units in various communication protocols, such as J1850 (VPM and PWM), international standards organization (ISO) 9141- 2 signal, communication collision detection (CCD) (e.g., Chrysler collision detection), data communication links (DCL), serial communication interface (SCI), Controller Area Network (CAN), Keyword 2000 (ISO 14230-4), on-board diagnostics (OBD) II or other communication protocols that are implemented in a vehicle. This allows the refrigerant recovery unit to communicate directly with the vehicle without the VCI (e.g., directly connected to the vehicle) or while the VCI is simply acting as a pass through. [0144] A software program (also referred to as computer control logic) may be stored in main memory 408b and/or secondary memory 410b. Software programs may also be received through communications interface 420b. Such software programs, when executed, enable the control system 400b to perform the features of the present invention, as discussed herein. In particular, the software programs, when executed, enable the processor 402b to perform the features of the present invention. Accordingly, such software programs may represent controllers of the control system 400b.

[0145] In variations where the invention is implemented using software, the software may be stored in a computer program product and loaded into control system 400 using hard drive 412b, removable storage unit 416b, and/or the communications interface 420b. The control logic (software), when executed by the processor 402b, causes the controller 216b, for example, to perform the functions of the invention as described herein. In another variation, aspects of the present invention can be implemented primarily in hardware using, for example, hardware components, such as application specific integrated circuits (ASICs), field programmable gate array (FPGA). Implementation of the hardware state machine so as to perform the functions described herein will be apparent to persons skilled in the relevant art(s).

[0146] It is to be understood that any feature described in relation to any one aspect may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the disclosed aspects, or any combination of any other of the disclosed aspects.

[0147] The many features and advantages of the disclosure are apparent from the detailed specification, and, thus, it is intended by the appended claims to cover all such features and advantages of the disclosure which fall within the true spirit and scope of the disclosure. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and, accordingly, all suitable modifications and equivalents may be resorted to that fall within the scope of the disclosure.

Claims

CLAIMS What is claimed is:

1. A refrigerant recovery unit, the unit comprising:

a charging circuit configured to charge a refrigerant into a refrigerant system, wherein the charging circuit comprises one or more service hoses;

a refrigerant container in fluid communication with the charging circuit;

a scale capable of measuring a weight of the refrigerant container; and

a recirculating circuit configured to recirculate refrigerant from a coupler located at one end of the one or more service hoses to a component capable of removing vapor from the refrigerant.

2. The refrigerant recovery unit of Claim 1, additionally comprising one or more valves capable of opening and closing a fluid path of the recirculating circuit.

3. The refrigerant recovery unit of Claim 2, wherein the one or more valves are solenoid controlled valves in connection with a controller.

4. The refrigerant recovery unit of Claim 2, wherein the charging circuit and the recirculation circuit share a refrigerant flow path conduit portion.

5. The refrigerant recovery unit of Claim 2, wherein the charging circuit and the recirculation circuit have separate parallel flow path conduits portions proximate to the coupler ends providing a connection to the refrigerant system.

6. The refrigerant recovery unit of Claim 5, wherein a diameter of the recirculating circuit is relatively smaller than a diameter of the charging circuit to increase charge accuracy of the refrigerant recovery unit.

7. The refrigerant recovery unit of Claim 5, wherein each of the separate flow path conduit portions of the recovery circuit and the recirculation circuit are controlled by one or more synchronized valves.

8. The refrigerant recovery unit of Claim 7, wherein the one or more valves are solenoid controlled valves in logical connection with a controller.

9. The refrigerant recovery unit of Claim 1, wherein the recirculating circuit is in fluid connection with a flow path conduit leading into an oil separator of the refrigerant recovery unit.

10. The refrigerant recovery unit of Claim 1, additionally comprising a control system in logical communication with a user's interface and one or more component of the refrigerant recovery unit.

11. A method of improving refrigerant charge accuracy using a refrigerant recovery unit, the method comprising:

recirculating refrigerant through a flow path that is connected to a coupler end of a first service hose;

measuring, with a scale, an initial reference weight of a refrigerant container after vapor refrigerant has been removed using the recirculating flow path;

transferring refrigerant to a refrigerant system; and

measuring, with the scale, a second weight of the refrigerant container.

12. The method of Claim 11, additionally comprising recirculating refrigerant through a flow path is connected to a coupler end of a second service hose.

13. The method of Claim 11, wherein said initial reference weight measurement are compared to said second weight measurement by a processor to determine if a weight of a target amount of refrigerant has been transferred into the refrigerant system.

14. The method of Claim 13, additionally comprising adding more refrigerant when the target weight of the amount of refrigerant is greater than the transferred refrigerant weight.

15. A method of improving refrigerant charge accuracy using a refrigerant recovery unit, the method comprising: opening a recirculating flow path that is connected near couplers of one or both a first service hose and a second service hose connected to the refrigerant system; and

keeping a constant refrigerant flow before and after a valve that regulates the refrigerant leaving the refrigerant recovery unit.

16. The method of Claim 15, additionally comprising removing vapor refrigerant from the recirculated refrigerant contained in one or both of the first service hose and the second service hose.

17. The method of Claim 16, additionally comprising measuring, by a scale, an initial reference weight of a refrigerant container after vapor refrigerant has been removed.

18. The method of Claim 17, wherein a processor compares said initial reference weight measurement to a second weight measurement to calibrate said constant flow.

19. The method of Claim 17, wherein a processor compares said initial reference weight measurement to said second weight measurement to determine if a weight of a target amount of refrigerant has been transferred into the refrigerant system.

20. The method of Claim 19, additionally comprising adding more refrigerant when the target weight of the amount of refrigerant is greater than the transferred refrigerant weight.