Patent Application
20140260354
The disclosure generally relates to servicing a refrigeration system. More particularly, 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.
Portable refrigerant recovery units or carts are 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.
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.
Accordingly, it is desirable to provide an improved refrigerant recovery device and method.
The foregoing needs are met, to a great extent, by some embodiments of the present invention, wherein in one respect an improved check valve assembly for servicing a refrigeration system is provided.
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.
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.
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.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description thereof herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention 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.
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 invention. 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 invention.
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.
As shown in
The check valve assembly 18 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.
The hose 20 is configured to convey refrigerant through the service hose 12/14. As is generally known, the hose 20 has a nominal inside diameter and a length. Given the nominal inside diameter and a length, an interior volume of the hose 20 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 20 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 20 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 20 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 20 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 120.6 g for the hose 20 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 1%-5%. Factors that may cause this variance include wear on the hose 20, excessive pressure within the hose 20, contaminants within the refrigerant that have different densities or other properties, and the like.
The refrigerant recovery unit 100 can be the AC1234™ from ROBINAIR® based in Owatonna, Minn. (Service Solutions U.S., LLC). The refrigerant recovery unit 100 includes a cabinet 102 to house components of the system (See
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 as shown in
According to an embodiment, the control panel 104 includes a user interface 114 to provide the user with an interface to interact and operate the refrigerant recovery unit 100. The user interface 114 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 116 is provided to print out information, such as test results.
The cabinet 102 further includes a plurality attachment points 124, 128 for the service hoses 12, 14 that connect the refrigerant recovery unit 100 to a refrigerant containing device, such as a refrigeration system (shown in
During servicing of a refrigeration system (shown in
In the particular example shown, the refrigerant recovery unit 100 is coupled to the refrigeration system 200 via the service hose 12 (high side) and the service hose 14 (low side). In general, the various hoses and couplers are configured to be closed until they are coupled to the refrigerant recovery unit 100 and/or the refrigeration system 200. In this manner, refrigerant leakage may be minimized or prevented.
The recovery cycle is initiated by the opening of high pressure and low-pressure solenoids 276, 278, respectively. This allows the refrigerant within the vehicle's refrigeration system 200 to flow through the service hoses 12 and 14 and then through a recovery valve 280 and a check valve 282. The service hoses 12 and 14 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 200. To continue, 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 valve 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 is 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. 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, compressor) 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.
A high-side clear valve 323 may optionally be coupled to the output of the compressor 256 to release the recovered refrigerant transferred from compressor 256 directly into a storage tank 212, instead of through a path through the normal discharge valve 284.
The heated compressed refrigerant exits the oil separator 286 and then travels 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 is 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 drains the recovered oil into a container 257. Finally, the recovered refrigerant flows through a normal discharge check valve 294 and into the storage tank 212.
The evacuation cycle begins by the opening of high pressure and low-pressure solenoids 276 and 278 and valve 296, leading to the input of a vacuum pump 258. Prior to opening valve 296, an air intake valve (not shown) is opened, allowing the vacuum pump 258 to start exhausting air. The vehicle's refrigeration system 200 is then evacuated by the closing of the air intake valve 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 and 232, optionally, coupled to the high side 226 and low side 230 of the vehicle's refrigeration system 200 and to the controller 216, the controller 216 turns off valve 296 and this begins the recharging cycle. Here again, the minimal restriction to flow from the refrigeration system 200 provided by the service hoses 12 and 14 facilitate efficient evacuation of the refrigeration system 200.
The recharging cycle begins by opening charge valve 298 to allow the refrigerant in storage tank 212, which is at a pressure of approximately 70 psi or above, to flow into the service hose 12. Once sufficient refrigerant pressure has developed within the service hose 12 to overcome the cracking pressure, the refrigerant is allowed to flow through the respective check valve assembly 18 and then through the high side of the vehicle's refrigeration system 200. The flow is through charge valve 298 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 12. Because the service hose 12 is configured to maintain the refrigerant in the liquid state and the internal volume of the service hose 12 is known, the weight of refrigerant remaining in the service hose 12 is readily determinable. Optionally, charge valve 299 may be opened to charge the low side. The charge valve 299 may be opened alone or in conjunction with charge valve 298 to supply a flow of refrigerant to the service hose 14. In a manner similar to the service hose 12, the service hose 14 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 18 and then charge the vehicle's refrigeration system 200. The storage tank 212 may be disposed on a scale (not shown) that measures the weight of the refrigerant in the storage tank.
Following recharging, any refrigerant remaining in the service hoses 12 and/or 14 may be recovered. For example, the user may be instructed to remove the service couplers 16 from the refrigeration system 200 so that refrigerant is not drawn out of the refrigeration system 200. Once the service couplers 16 have been removed, a recovery cycle as described herein may be performed to remove any remaining refrigerant in the service hoses 12 and/or 14.
Other components shown in
High side clearing valves 318 may be used to clear out part of the high-pressure side of the system. The high side clearing valves 318 may include valve 323 and check valve 320. Valve 323 may be a solenoid valve. When it is desired to clear part of the high side, valve 323 is opened. Operation of the compressor 256 will force refrigerant out of the high pressure side through valves 323 and 320 and into the storage tank 212. During this procedure the normal discharge valve 284 may be closed.
A deep recovery valve 324 is provided to assist in the deep recovery of refrigerant. When the refrigerant from the refrigeration system 200 has, for the most part, entered into the refrigerant recovery unit 100, the remaining refrigerant may be extracted from the refrigeration system 200 by opening the deep recovery valve 324 and turning on the vacuum pump 258.
In another embodiment, in order to charge the refrigeration system 200, the power charge valve 326 may be opened and a tank fill structure 332 may be used. Alternatively or in addition to, the tank fill structure 332 may also be used to fill the storage tank 212. In order to obtain refrigerant from a refrigerant source, the refrigerant recovery unit 100 may include the tank fill structure 332, and valves 328 and 330. The tank fill structure 332 may be configured to attach to a refrigerant source. The valve 330 may be a solenoid valve and the valve 328 may be a check valve. In other embodiments, valve 330 may be a manually operated valve.
When it is desired to allow refrigerant from a refrigerant source to enter the refrigerant recovery unit 100, the tank fill structure 332 is attached to the refrigerant source and the tank fill valve 330 is opened. The check valve 328 prevents refrigerant from the refrigerant recovery unit 100 from flowing out of the refrigerant recovery unit 100 through the tank fill structure 332. When the tank fill structure 332 is not connected to a refrigerant source, the tank fill valve 330 is kept closed. The tank fill valve 330 may be connected to and controlled by the controller 216.
The tank fill structure 332 may be configured to be seated on the scale 334 configured to weigh the tank fill structure 332 in order to determine an amount of refrigerant stored in the tank fill structure 332. The scale 334 may be operatively coupled to the controller 216 and provide a measurement of a weight of the tank fill structure 332 to the controller 216. The controller 216 may cause a display of the weight of the tank fill structure 332 on the display 110.
Aspects of the refrigerant recovery unit 100 may be implemented via control system 400 using software or a combination of software and hardware. In one variation, aspects of the present invention may be directed toward a control system 400 capable of carrying out the functionality described herein. An example of such a control system 400 is shown in
Control system 400 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 400 allows the refrigerant recovery unit to direct communicate and diagnose the vehicle under service. In another embodiment, the control system 400 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 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.
The control system 400 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 400 may include a processor 402 connected to a communication infrastructure 404 (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.
The control system 400 may include a display interface 406 that forwards graphics, text, and other data from memory and/or the user interface 114, for example, via the communication infrastructure 404 for display on the display 110. The communication infrastructure 404 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 400 may include a main memory 408, preferably random access memory (RAM), and may also include a secondary memory 410. The secondary memory 410 may include a hard drive 412 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 414 and a removable storage unit 416, 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 414.
The control system 400 may also include a communications interface 420 for allowing software and data to be transferred between the control system 400 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.
The control system 400 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.
A software program (also referred to as computer control logic) may be stored in main memory 408 and/or secondary memory 410. Software programs may also be received through communications interface 420. Such software programs, when executed, enable the control system 400 to perform the features of the present invention, as discussed herein. In particular, the software programs, when executed, enable the processor 402 to perform the features of the present invention. Accordingly, such software programs may represent controllers of the control system 400.
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 412, removable storage unit 416, and/or the communications interface 420. The control logic (software), when executed by the processor 402, causes the controller 216, 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).
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
