| Microvalve device suitable for controlling a variable displacement compressor -> Monitor Keywords |
|
|
 
Microvalve device suitable for controlling a variable displacement compressorRelated Patent Categories: Pumps, Condition Responsive Control Of Drive Transmission Or Pump Displacement, Adjustable Cam Or Linkage, Axial Cam, With Sump Pressure ActuationMicrovalve device suitable for controlling a variable displacement compressor description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070172362, Microvalve device suitable for controlling a variable displacement compressor. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of U.S. patent application Ser. No. 11/437,022, filed May 18, 2006 which was a continuation of International Application No. PCT/US2004/039517, filed Nov. 24, 2004, which claims priority from U.S. Provisional Application No. 60/525,224, filed Nov. 24, 2003 and U.S. Provisional Application No. 60/559,355, filed Apr. 2, 2004. The disclosures of all four applications are incorporated herein by reference. BACKGROUND OF INVENTION [0003] 1. Field of the Invention [0004] The present invention relates in general to control valves and to semiconductor electromechanical devices, and in particular, to a control valve for a variable displacement gas compressor for use in an air conditioning or refrigeration system, which control valve is positioned by a microvalve device (micromachined pilot valve). [0005] 2. Description of the Related Art [0006] MEMS (MicroElectroMechanical Systems) is a class of systems that are physically small, having features with sizes in the micrometer range. These systems have both electrical and mechanical components. The term "micromachining" is commonly understood to mean the production of three-dimensional structures and moving parts of MEMS devices. MEMS originally used modified integrated circuit (computer chip) fabrication techniques (such as chemical etching) and materials (such as silicon semiconductor material) to micromachine these very small mechanical devices. Today there are many more micromachining techniques and materials available. The term "microvalve" as used in this application means a valve having features with sizes in the micrometer range, and thus by definition is at least partially formed by micromachining. The term "microvalve device" as used in this application means a device that includes a microvalve, and that may include other components. It should be noted that if components other than a microvalve are included in the microvalve device, these other components may be micromachined components or standard sized (larger) components. [0007] Various microvalve devices have been proposed for controlling fluid flow within a fluid circuit. A typical microvalve device includes a displaceable member or valve movably supported by a body and operatively coupled to an actuator for movement between a closed position and a fully open position. When placed in the closed position, the valve blocks or closes a first fluid port that is placed in fluid communication with a second fluid port, thereby preventing fluid from flowing between the fluid ports. When the valve moves from the closed position to the fully open position, fluid is increasingly allowed to flow between the fluid ports. U.S. Pat. No. 6,540,203 entitled "Pilot Operated Microvalve Device", the disclosures of which are hereby incorporated herein by reference, describes a microvalve device consisting of an electrically operated pilot microvalve and a pilot operated microvalve whose position is controlled by the pilot microvalve. U.S. Pat. No. 6,494,804 entitled "Microvalve for Electronically Controlled Transmission", the disclosures of which are hereby incorporated herein by reference, describes a microvalve device for controlling fluid flow in a fluid circuit, and includes the use of a fluid bleed path through an orifice to form a pressure divider circuit. The two US patents mentioned above are multilayer microvalves in that the valve bodies are formed of multiple layers or plates. These layers may be formed and joined in any suitable fashion, including those disclosed in U.S. Patent Application Publication No. US 2002/0174891A, the disclosures of which are incorporated herein by reference. [0008] In addition to generating a force sufficient to move the displaced member, the actuator must generate a force capable of overcoming the fluid flow forces acting on the displaceable member that oppose the intended displacement of the displaced member. These fluid flow forces generally increase as the flow rate through the fluid ports increases. [0009] Variable displacement gas compressors are known which can be utilized in systems such as automotive air conditioning systems using a compressible refrigerant such as R-12, (increasingly) R-134a, R-600, or CO.sub.2. [0010] In such an air conditioning system, the refrigerant gas is compressed in a gaseous form by a compressor and discharged by the compressor at a high pressure and temperature. The gas moves to a condenser, where the high pressure, high temperature gas condenses into a high pressure, high temperature liquid, the energy released in this state change being transferred to air passing over the condenser fins in the form of heat. From the condenser, the liquid travels through an expansion device, where the pressure (and temperature) of the liquid is lowered. The cool low pressure liquid to an evaporator where the liquid absorbs heat for air passing over the evaporator coils, thus cooling the air. As the refrigerant absorbs heat, the refrigerant changes state from a liquid to a gas. The cooled air passes out into the compartment to be cooled. The degree to which the air is cooled is proportional to the amount of heat transferred to the refrigerant gas, and the amount of heat transferred to the refrigerant gas is directly proportional to how much gas is compressed within the compressor to drive the process. The amount of gas being compressed is controlled within a variable displacement compressor by controlling the amount of displacement of a piston within a compression chamber of the variable displacement compressor. It is known to use a control valve to control the displacement of the pistons in variable displacement compressors. [0011] A key concern in designing a cooling system utilizing refrigerant gas is too ensure that the liquid from the condenser does not flow in a quantity and temperature to push the evaporator below the freezing point of water. If there is too much heat absorption by the gas within the evaporator, the water found on the fins and tubes through condensation of water vapor from air passing over the evaporator will freeze up, choking off air flow through the evaporator, thereby cutting off the flow of cool air to the passenger compartment. For this reason, most conventional control valves are calibrated to change the stroke (displacement) of the compressor to control the pressure of the gas returning to the compressor at a set pressure. The gas returns to the suction area of the compressor. The pressure in this area of the compressor is known as the suction pressure. The desired suction pressure, around which the stroke of the compressor is changed, is known within the art as the set-point suction pressure. [0012] In 1984, a variable displacement refrigerant compressor was introduced which adjusted the flow of the refrigerant gas through the system by varying the stroke of the piston in the pumping mechanism of the compressor in the manner just described. This system was designed for use in an automobile, deriving power to drive the compressor using a drive belt coupled to the vehicle's engine. In operation, when the A/C system load is low, the piston stroke of the compressor is shortened so that the compressor pumps less refrigerant per revolution of the engine drive belt. This allows just enough refrigerant to satisfy the cooling demands of the automobile's occupants. When the A/C system load is high, the piston stroke is lengthened and pumps more refrigerant per revolution of the engine drive belt. [0013] A description of this prior art variable displacement compressor and a conventional pneumatic control valve (CV) is found in U.S. Pat. No. 4,428,718 by Skinner (Skinner '718) which is assigned to the General Motors Corporation of Detroit, Mich. The Skinner '718 description and explanation of the variable displacement compressor, general function, and interaction of the CV with the compressor is hereby incorporated by reference. [0014] FIG. 9 shows a variable displacement refrigerant compressor as described by Skinner '718. There is shown a variable displacement refrigerant compressor 210 of the variable angle wobble plate type connected in an automotive air conditioning system having the normal condenser 212, orifice tube 214, evaporator 216 and accumulator 218 arranged in that order between the compressor's discharge and suction sides. The compressor 210 comprises a cylinder block 220 having a head 222 and a crankcase 224 sealingly clamped to opposite ends thereof. A drive shaft 226 is supported centrally in the compressor at the cylinder block 220 and crankcase 224 by bearings. The drive shaft 226 extends through the crankcase 224 for connection to an automotive engine (not shown) by an electromagnetic clutch 236 which is mounted on the crankcase 224 and is driven from the engine by a belt 238 engaging a pulley 240 on the clutch 236. [0015] The cylinder block 220 has five axial cylinders 242 through it (only one being shown), which are equally spaced about and away from the axis of drive shaft 226. The cylinders 242 extend parallel to the drive shaft 226 and a piston 244 is mounted for reciprocal sliding movement in each of the cylinders 242. A separate piston rod 248 connects the backside of each piston 244 to a non-rotary, ring-shaped, wobble plate 250. [0016] The non-rotary wobble plate 250 is mounted at its inner diameter 264 on a journal 266 of a rotary drive plate 268. The drive plate 268 is pivotally connected at its journal 266 by a pair of pivot pins (not shown) to a sleeve 276 which is slidably mounted on the drive shaft 226, to permit angulation of the drive plate 268 and wobble plate 250 relative to the drive shaft 226. The drive shaft 226 is drivingly connected to the drive plate 268. The wobble plate 250 while being angularable with the rotary drive plate 268 is prevented from rotating therewith by a guide pin 270. [0017] The angle of the wobble plate 250 is varied with respect to the axis of the drive shaft 226 between the solid line large angle position shown in FIG. 9, which is full-stroke, to the zero angle phantom-line position shown, which is zero stroke, to thereby infinitely vary the stroke of the pistons and thus the displacement or capacity of the compressor between these extremes. There is provided a split ring return spring 272 which is mounted in a groove on the drive shaft 226 and has one end that is engaged by the sleeve 276 during movement to the zero wobble angle position and is thereby conditioned to initiate return movement. [0018] The working ends of the cylinders 242 are covered by a valve plate assembly 280, which is comprised of a suction valve disk and a discharge valve disk, clamped to the cylinder block 220 between the latter and the head 222. The head 222 is provided with a suction area 282, which is connected through an external port 284 to receive gaseous refrigerant from the accumulator 218 downstream of the evaporator 216. The suction area 282 is open to an intake port 286 in the valve plate assembly 280 at the working end of each of the cylinders 242 where the refrigerant is admitted to the respective cylinders on their suction stroke each through a reed valve formed integral with the suction valve disk at these locations. Then on the compression stroke, a discharge port 288 open to the working end of each cylinder 242 allows the compressed refrigerant to be discharged into a discharge area 290 in the head 222 by a discharge reed valve which is formed integral with the discharge valve disk. The compressor's discharge area 290 is connected to deliver the compressed gaseous refrigerant to the condenser 212 from whence it is delivered through the orifice tube 214 back to the evaporator 216 to complete the refrigerant circuit as shown in FIG. 9. [0019] The wobble plate angle and thus compressor displacement can be controlled by controlling the refrigerant gas pressure in the sealed interior 278 of the crankcase behind the pistons 244 relative to the suction pressure. In this type of control, the angle of the wobble plate 250 is determined by a force balance on the pistons 244 wherein a slight elevation of the crankcase-suction pressure differential above a suction pressure control set-point creates a net force on the pistons 244 that results in a turning moment about the wobble plate pivot pins (not shown) that acts to reduce the wobble plate angle and thereby reduce the compressor capacity. [0020] An important element of the variable displacement compressor is a pneumatic control valve 300 inserted into the head portion 222 of the compressor. CV 300 senses the A/C load by sensing the pressure state (the suction pressure) of the refrigerant gas returning to the compressor. The CV is operably connected to the crankcase chamber 278. There are channels in the cylinder block 220 and the head 222 of the compressor for gas flow between the CV and suction area 282, discharge area 290 and crankcase chamber 278 of the compressor. The CV controls the displacement of a piston 244 within the compressor by controlling the pressure of gas in the crankcase chamber 278 that acts on the backside of the pistons 244 and the wobble plate 250. [0021] Control valve 300 inserts into a stepped, blind CV cavity 298 formed in the compressor head 222. The blind end of CV cavity 298 communicates directly with discharge area 290 through port 292. CV cavity ports 294 and 295 communicate with the crankcase chamber 278. CV cavity port 296 communicates with the suction area 282. CV 300 is sealed into the CV cavity 298 so that particular features of the CV align with ports 292, 294, 295 and 296. [0022] FIG. 10 illustrates, in more detail, the pneumatic CV 300 depicted in FIG. 9. The valve 300 comprises a valve body 310 and valve bellows cover 312. Grooves 314, 316 and 318 are formed in the valve body to position o-rings, which seal against the walls of the CV cavity 298. A groove 299 formed in the wall of the CV cavity 298 holds an o-ring, which seals against the valve bellows cover 312. This arrangement of o-rings seals the valve into four regions within the CV cavity 298 that are sealed with respect to each other and are each in gas communication with one of ports 292, 294, 295 or 296. [0023] CV 300 has an upper valve chamber 330 that communicates to the compressor discharge area 290 via (through) filter 320 and CV cavity port 292. A mid-valve chamber 322 communicates to the crankcase chamber 278 via an opening 321 in the valve body 310. A central passageway 326 in the valve body 310 communicates with the crankcase chamber 278 via port 295. A lower valve chamber 328 communicates with the compressor suction area 282 through opening 327 in the valve bellows cover 312 and via port 296. Continue reading about Microvalve device suitable for controlling a variable displacement compressor... Full patent description for Microvalve device suitable for controlling a variable displacement compressor Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Microvalve device suitable for controlling a variable displacement compressor patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Microvalve device suitable for controlling a variable displacement compressor or other areas of interest. ### Previous Patent Application: Cleaning method of a rotary piston vacuum pump Next Patent Application: Centrifugal motor-compressor unit Industry Class: Pumps ### FreshPatents.com Support Thank you for viewing the Microvalve device suitable for controlling a variable displacement compressor patent info. IP-related news and info Results in 0.22341 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
