US20060153696A1 - Screw pump - Google Patents
Screw pump Download PDFInfo
- Publication number
- US20060153696A1 US20060153696A1 US10/531,558 US53155803A US2006153696A1 US 20060153696 A1 US20060153696 A1 US 20060153696A1 US 53155803 A US53155803 A US 53155803A US 2006153696 A1 US2006153696 A1 US 2006153696A1
- Authority
- US
- United States
- Prior art keywords
- pump
- temperature
- rotor
- fluid
- pump according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
- F04C28/28—Safety arrangements; Monitoring
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
- F01C21/00—Component parts, details or accessories not provided for in groups F01C1/00 - F01C20/00
- F01C21/10—Outer members for co-operation with rotary pistons; Casings
- F01C21/102—Adjustment of the interstices between moving and fixed parts of the machine by means other than fluid pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C18/14—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons
- F04C18/16—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with toothed rotary pistons with helical teeth, e.g. chevron-shaped, screw type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C28/00—Control of, monitoring of, or safety arrangements for, pumps or pumping installations specially adapted for elastic fluids
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/04—Heating; Cooling; Heat insulation
Definitions
- This invention relates to the field of vacuum pumps.
- thermal control of vacuum pumps with a screw type configuration is particularly important.
- Screw pumps usually comprise two spaced parallel shafts each carrying externally threaded rotors, the shafts being mounted in a pump body such that the threads of the rotors intermesh. Close tolerances between the rotor threads at the points of intermeshing and with the internal surface of the pump body, which acts as a stator, causes volumes of gas being pumped between an inlet and an outlet to be trapped between the threads of the rotors and the internal surface and thereby urged through the pump as the rotors rotate.
- Prior art screw pumps use a water cooling jacket around sections of the machine in order to remove the heat of compression.
- the inlet of the machine does not have any cooling system since, at low pressures, there is little heat of compression to be removed from the inlet. As the pressure increases any additional heat is dispersed from the inlet by the increased gas flow through it.
- surface temperatures within the inlet of the pump may reduce significantly and form cold spots such that gaseous waste products from the evacuation chamber condense into liquid pools in these cooler regions. These pools can be formed from highly corrosive acid or base fluids and can lead to damage of the pump components, which, in turn, can reduce the life of the device.
- Double ended screw pumps are known where a single inlet serves two outlets, the rotors being mounted in a co-linear fashion. In such a pump a disparity in temperature between the inlet and the outlet sections of the pump is more pronounced and concentricity of the bores within the housing components becomes important. If the housing components move out of alignment the rotor is more likely to clash with the stator as the already small tolerances reduce even further or are eliminated.
- Screw pumps are increasingly being utilised in a broad range of applications. For example within a pharmaceutical process area the same pump may be required to perform numerous different applications. Whilst the configuration of a pump may be tailored to a particular application, once the application is altered, ideal conditions will no longer be present and the pump will not be performing at peak/optimum efficiency.
- a pump comprising:
- the first temperature sensor may be located at the stator, whereas the second temperature sensor may be located either in the exhaust plenum or within the housing, in fluid communication with process gas in an exhaust portion of the rotor, alternatively it may be situated in the gear box of the pump
- the thermal control means may comprise first and second control means for controlling the temperature of any fluid in the first and second channels respectively.
- Either thermal control means at least one of each of a variable speed flow pump, a thermostatic control valve and a heat exchanger. They may be arranged to control the temperature of the fluid in the respective channels dependant on the magnitude of one or more of the sensors' outputs.
- the thermal control means may include/be controlled by a microprocessor.
- One of the thermostatic control valves may comprise a mechanical differential temperature valve.
- This valve may comprise a third fluid channel in thermal communication with the second fluid channel.
- a flow restrictor may be provided within this third fluid channel to control the rate of fluid therethrough.
- the position of this flow restrictor may be governed by signals received from the first and second sensors via signal receptors which may also form part of the valve.
- Each signal receptor may comprise a sealed component, the volume of which may expand in use. The degree of expansion being dependent on the magnitude of the signal received and determining the relative position of the restrictor within the third fluid channel.
- the sealed component of the signal receptor may comprise an expandable bellows.
- the flow restrictor may comprise a spindle and a seat. The spindle acting co-operatively with the seat to open and close an aperture to control the flow of fluid therethrough.
- the pump may be of any known form, for example but not strictly limited to; a screw pump, a claw pump or a Roots pump.
- a double-ended pump comprising at least one rotor, comprising:
- a valve comprising:
- a method for releasing the rotors of a pump that have seized due to the presence of deposits of a substance which has solidified on the internal working surfaces of the pump on cooling comprising the steps of:
- a clearance between a rotor and stator within a pump comprising the steps of:
- the method steps may be repeated automatically at predetermined time intervals in order to manage perturbations in the configuration of the pump over time.
- the predetermined temperature difference may be modified at predetermined time intervals to cause the clearance between components to be altered such that cumulative deposits can be dislodged from the surfaces of the components of the pump.
- the thermal controller may comprise a microprocessor which may be embodied in a computer, which in turn is optionally programmed by computer software which, when installed on the computer, causes it to perform the method steps (a) to (e) mentioned above.
- the present invention enables a pump to be subject to an improved level of thermal control. This allows benefits to be achieved during operation of the apparatus in terms of providing optimised running clearances enhancing the tolerance of the pump to excessive exhaust back pressures, reducing the occurrence of cold spots in the inlet of the pump, reducing thermal lag in the apparatus and enhancing the likelihood of restart in circumstances where deposits are formed due to cooling.
- FIG. 1 illustrates a schematic plan cross section of a screw pump of the present invention
- FIG. 2 illustrates a plan cross section of a double-ended screw pump of the present invention
- FIG. 3 is a schematic of a temperature control circuit of the present invention.
- FIG. 4 illustrates further detail of the interface between the rotor and the stator of the pump in FIG. 2 ;
- FIG. 5 illustrates a more sophisticated version of the present invention
- FIG. 6 shows a further example of the present invention for use in more severe environments
- FIG. 7 shows detail of a differential temperature valve for use in the pump of FIG. 6 :
- FIG. 8 illustrates a Roots blower implementing thermal control of the present invention.
- Screw pumps are illustrated in FIGS. 1 and 2 .
- Two rotors 1 are provided within an outer housing 2 .
- the two contra-rotating, intermeshing rotors 1 are positioned such that their central axes lie parallel to one another.
- the rotors 1 are mounted in the housing 2 via bearings 3 .
- the single ended pump of FIG. 1 comprises an inlet stator 4 and an exhaust stator 5
- the double ended pump of the example in FIG. 2 comprises an inlet stator 4 positioned between two exhaust stators 5 .
- the housing 2 is provided as a double skinned construction.
- the internal skin acts as the stator of the pump.
- a cavity 6 is provided between the skins of the housing 2 such that a cooling fluid, such as water, can be circulated around the stator in order to conduct heat away from the working section of the pump.
- This cavity 6 encircles the full length of the stator i.e. over the inlet stator 4 as well as the exhaust stators 5 . Cooling fluid is circulated through this cavity to draw heat away from the hot surface.
- the waste products passing through the pump comprise a waxy or highly viscous substance and deposits are formed on the surfaces of the pump during operation. On shut down of the pump, these deposits cool and may solidify. Where such deposits are located in clearance regions between components, they can cause the pump to seize up.
- the motor may then provide insufficient torque to overcome this additional friction and cause the rotor to rotate. Additional torque can be applied using a leverage bar inserted into a socket on the shaft, which can then be rotated manually.
- a leverage bar inserted into a socket on the shaft, which can then be rotated manually.
- Such a technique exerts a significant load on the rotor and may cause damage.
- the fluid in the cavity 6 of the housing 2 may be heated to raise the temperature of the stators 4 , 5 and the rotors 1 . This can enhance the pliability of the residue and may assist in releasing the mechanism.
- FIG. 3 shows how fluid circuits 11 , 12 , 12 a and 15 may be used to control thermal conditions within the pump.
- the cooling liquid typically a mixture of water and anti-freeze
- a second fluid circuit 12 comprises a pressurised water circuit and a thermostatic control valve 13 .
- mains water is provided to this circuit at inlet 25 and is removed at outlet 26 .
- a heat exchange component 14 is provided between these two fluid circuits 11 , 12 .
- the valve 13 receives an input signal from a thermal sensor 21 located at the stator and uses this to maintain a suitable flow rate in the second circuit 12 to govern the temperature gradient over the heat exchange component 14 . This temperature gradient, in turn, maintains the temperature of the first circuit 11 .
- the rotor 1 comprises a threaded section 9 and a separate shaft component 8 as illustrated in FIG. 2 .
- the threaded section 9 is provided with an internal cooling cavity 7 , into which is inserted the body of a separate shaft 8 .
- the body of shaft 8 is fractionally smaller in diameter than the diameter of the cooling cavity 7 within the body of the rotor.
- a cooling channel is provided, through which a coolant material, typically oil, may be passed. This channel is kept small to encourage the flow speed of the coolant to be as high as possible, in order to enhance the cooling function by maintaining the temperature difference between the rotor and the coolant and transporting heat back to a coolant reservoir.
- the cooling system inlet and outlet are provided through the shaft component 8 .
- This circuit 15 comprises a circulation pump 19 a filter 20 and a heat exchange component 14 a .
- This heat exchange component is in contact with a second cooling circuit 12 a and comprises a further thermostatic control valve 16 .
- the thermostatic control valve 16 receives an input signal from a second thermal sensor 22 which indicates the temperature of the rotor either via the oil from circuit 15 or through the process gases within the latter stages of the rotor. Temperature may be monitored within the exhaust plenum (i.e. the cavity between the end of the rotor and the stator wall) but here, the temperature will rapidly fall below that of the rotor.
- the rotor to stator clearance d (as illustrated in FIG. 4 ) in a screw pump is a function of this difference in temperature between the rotor and the stator.
- This clearance d determines the level of leakage of process gas between the rotor and the stator, such that the volume of leakage is proportional to d 3 for intermediate, transitional flow as shown in “Modern vacuum practice” by Nigel Harris, McGraw Hill (p 231).
- the performance of the pump can be optimised by controlling the temperatures of these components. Furthermore, it is beneficial to be able to maintain clearances d such that any particulate content of the process gas does not form a blockage within these clearances and thus inhibit the free running of the rotor 1 . Such obstruction can severely affect the performance of the pump through restriction of through flow of the process gas but also through additional torque that must be applied by the motor in order to maintain the appropriate speed of rotation of the rotor.
- thermocontrol circuit within the rotor it is possible to thermostatically control rotor temperature relative to the stator temperature to optimise rotor/stator clearance d.
- the present invention can be used simply to avoid cold spots and thus eliminate corrosion due to condensation build up as discussed above.
- input signals can be taken from sensors mounted on each of the stator 4 , 5 and the rotor 1 and these signals can be analysed/processed by a closed loop control system to maintain a set temperature, for example to be less than 135° C. This allows a pump using the present invention to safely process materials with a known auto-ignition temperature.
- FIG. 5 illustrates how a processor or central processing unit (CPU) 27 may be incorporated into the system to receive signals indicative of the rotor and stator temperatures from sensors 22 a and 21 a respectively. These signals provide input to allow the processor 27 to determine the required temperatures of each of the components. The processor 27 then controls electronically activated valves 13 a and 16 a to provide a suitable level of coolant fluid to the heat exchange components 14 , 14 a to achieve the required thermal balance and subsequent clearance d.
- CPU central processing unit
- a dry pump Under normal steady state operation, a dry pump will attain a particular pumping speed determined by the clearance between the rotor and the stator. If the inlet pressure to the pump is increased more gas will enter the pump. This additional gas will cause the rotors to cool down with respect to the stator and hence the clearance d between these two components will increase. It follows that, at higher pressures, a significant amount of leakage around the rotor will occur. This is particularly problematic when pumping gas species such as helium, which typically result in low pump speeds and gas throughput being achieved when approaching atmospheric pressures. With the control feature of the present invention it is possible to artificially reduce the clearance d between the rotor and the stator. Consequently leakage around the rotor may be reduced and the efficiency of the pump can be improved significantly.
- the temperature control can be dynamic within a particular process. On start up there will typically be a greater temperature difference since the temperature of the rotor increases at a faster rate than the stator due to the significant difference in thermal mass of the relative components. However, once the pump has reached a steady state this temperature difference will be reduced. By performing the temperature control dynamically, this early difference can be minimised such that the clearance d can be maintained at an approximately steady value. This, in turn, will lead to a more consistent level of pump efficiency.
- the dynamic control of the clearances may be implemented in a cyclic manner when the pump is operating under normal conditions. At predetermined intervals the thermal conditions can be modified to reduce the clearances between the rotor and the stator for a short period of time. This will have the effect of removing/dislodging process deposits that have become adhered to these components. If this is repeated at intervals the cumulative build up of solid matter on the internal surfaces of the pump can be substantially reduced thus preventing seizure of the pump.
- Seizure of the pump may be further be avoided by provision of an additional sensor for monitoring either the pressure within the pump or the power consumption of the pump. If either of these values increase significantly, this may be an indication that the clearances are becoming obstructed and that seizure is imminent. By monitoring these values it is possible to initiate a condition of maximum cooling of the rotor component to maximise the clearance between the rotor 1 and the stator 4 , 5 and thus prevent seizure of the pump.
- the thermal control means may be provided by a purely mechanical means as illustrated in FIGS. 6 and 7 where a particular temperature difference can be automatically maintained between the stator and the rotor.
- the mechanical thermal control device 24 is directly connected to a sensor 22 located as described above to indicate the rotor temperature through the process gas within the swept volume or oil temperature within the gearbox and also to a sensor 23 located within the stator of the pump. This latter sensor 23 may be located in a similar position to sensor 21 which provides input to the thermal control valve 13 in FIG. 3 .
- Each end of the differential temperature valve experiences a different temperature from each sensor causing a sealed sensor/bellows arrangement to be heated thus causing an expansion of the bellows.
- These two expanding bellows arrangements act in combination to position an internal valve.
- This valve position governs the amount of cooling fluid that may pass through the thermal circuit and thus alters the heat removal of the heat exchange unit 14 a .
- This controls the clearances within the pump by modifying the temperatures of the pump components.
- This simpler example maintains a temperature difference between the rotor 1 and the stator 4 , 5 rather than actively controlling each component individually.
- the valve 24 can be physically altered, for example, by restricting the expansion of one of the bellows components to adjust the magnitude of temperature difference between the rotor 1 and the stator 4 , 5 , thus allowing different processes to be accommodated.
- the present invention is not restricted for use in screw pumps and may readily be applied to other types of pump such as claw pumps or Roots pumps. Indeed in some Roots blowers, significantly higher exhaust pressures (in some cases up to 2 to 3 bar) can be experienced. These raised pressures lead to a notable increase in component temperatures within the pump which can, in turn, lead to problems in maintaining appropriate clearances. By implementing dynamic thermal control according to the present invention these clearances can be maintained at consistent levels thus improving the tolerance of the pump to different operating conditions.
- a rotor 35 from a Roots blower is illustrated in FIG. 8 , in order to introduce the thermal control of the present invention it is necessary to introduce a cooling channel 34 into the rotor 35 in a similar manner to that found in the screw rotor 1 of FIG. 2 .
- the channel is kept small to encourage the flow speed of the coolant to be as high as possible, in order to enhance the cooling function by maintaining the temperature difference between the rotor 35 and the coolant and transporting heat back to a coolant reservoir, typically the gear box (not shown).
- the cooling channel inlet 32 and outlet 33 are provided through the rotor shaft component 31 .
- the cooling channel passes into each of the lobes 30 present on a Roots rotor 35 , there may be two lobes as illustrated or there could readily be three, four or even more lobes on the rotor.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Applications Or Details Of Rotary Compressors (AREA)
- Rotary Pumps (AREA)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB0223769.1 | 2002-10-14 | ||
GBGB0223769.1A GB0223769D0 (en) | 2002-10-14 | 2002-10-14 | A pump |
PCT/GB2003/004415 WO2004036049A1 (en) | 2002-10-14 | 2003-10-10 | Screw pump |
Publications (1)
Publication Number | Publication Date |
---|---|
US20060153696A1 true US20060153696A1 (en) | 2006-07-13 |
Family
ID=9945809
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US10/531,558 Abandoned US20060153696A1 (en) | 2002-10-14 | 2003-10-10 | Screw pump |
Country Status (9)
Country | Link |
---|---|
US (1) | US20060153696A1 (ko) |
EP (1) | EP1552153A1 (ko) |
JP (1) | JP2006503220A (ko) |
KR (1) | KR101120887B1 (ko) |
CN (1) | CN1703584A (ko) |
AU (1) | AU2003271940A1 (ko) |
GB (1) | GB0223769D0 (ko) |
TW (1) | TW200422522A (ko) |
WO (1) | WO2004036049A1 (ko) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060269424A1 (en) * | 2005-05-27 | 2006-11-30 | Michael Henry North | Vacuum pump |
US20070145929A1 (en) * | 2005-12-21 | 2007-06-28 | Shimadzu Corporation | Vacuum pump |
US20100229626A1 (en) * | 2005-12-15 | 2010-09-16 | Clive Marcus Lloyd Tunna | Apparatus for Detecting a Flammable Atmosphere Within a Compressor, in Particular a Vacuum Pump |
US20170204860A1 (en) * | 2014-07-31 | 2017-07-20 | Edwards Japan Limited | Dry pump and exhaust gas treatment method |
US10487834B2 (en) | 2015-09-15 | 2019-11-26 | Gree Electric Appliances, Inc. Of Zhuhai | Screw compressor and a compressor body thereof |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DK1923771T3 (en) * | 2003-11-07 | 2015-06-01 | Asetek As | Cooling system for a computer system |
EP1784576B2 (en) † | 2004-09-02 | 2016-01-13 | Edwards Limited | Cooling of pump rotors |
GB0502149D0 (en) | 2005-02-02 | 2005-03-09 | Boc Group Inc | Method of operating a pumping system |
GB0508872D0 (en) * | 2005-04-29 | 2005-06-08 | Boc Group Plc | Method of operating a pumping system |
GB0525378D0 (en) | 2005-12-13 | 2006-01-18 | Boc Group Plc | Screw Pump |
KR101712962B1 (ko) | 2015-09-24 | 2017-03-07 | 이인철 | 냉각장치를 갖춘 진공펌프 |
EP3361099A1 (en) * | 2017-02-10 | 2018-08-15 | Entecnia Consulting, S.L.U. | Method of manufacturing and assembling a pump and vacuum pump |
CN108302040B (zh) * | 2018-03-14 | 2023-05-09 | 深圳市志橙半导体材料有限公司 | 一种干式真空泵的防卡死装置及防卡死方法 |
CN111749896B (zh) * | 2020-07-07 | 2022-11-08 | 山东顺和新材料科技有限公司 | 一种利用磁悬浮消除摩擦力的节能型空压机 |
Citations (6)
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US2906448A (en) * | 1954-10-28 | 1959-09-29 | W C Heraus G M B H | Roots type vacuum pumps |
US4294402A (en) * | 1977-10-26 | 1981-10-13 | Honeywell Inc. | Control devices for heaters |
US4983107A (en) * | 1987-05-15 | 1991-01-08 | Leybold Aktiengesellschaft | Multistage rotary piston vacuum pump having sleeves to fix shaft positions |
US4983106A (en) * | 1988-10-07 | 1991-01-08 | Societe Anonyme Dite: Alcatel Cit | Rotary screw machine with multiple chambers in casing for lubrication-coding fluid |
US5040949A (en) * | 1989-06-05 | 1991-08-20 | Alcatel Cit | Two stage dry primary pump |
US5961291A (en) * | 1996-08-30 | 1999-10-05 | Hitachi, Ltd. | Turbo vacuum pump with a magnetically levitated rotor and a control unit for displacing the rotator at various angles to scrape deposits from the inside of the pump |
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GB1160551A (en) * | 1965-06-11 | 1969-08-06 | Wellesley Ashe Kealy | Improvements in and relating to Temperature Responsive Control Apparatus |
DE2305502C3 (de) * | 1973-02-05 | 1979-07-19 | Thomas 3000 Hannover Baehr | Verfahren zum Steuern der dem Sekundärkreis eines Zweikreis-Heizungssystems zugeführten Wärmemenge und Steuerorgan hierfür |
DE2926599A1 (de) * | 1979-07-02 | 1981-01-15 | Battelle Institut E V | Heizkoerperthermostat |
GB2081845B (en) * | 1980-05-29 | 1985-02-13 | Trucktonics Ltd | Control valve |
DE3203322A1 (de) * | 1982-01-28 | 1983-09-22 | Heinrich Ing.(grad.) 5205 St. Augustin Hilbers | Energiesparende absperrung ohne fremdenergie fuer waerme/kaelte-verbraucher |
JPS59115492A (ja) * | 1982-12-22 | 1984-07-03 | Hitachi Ltd | 無給油式スクリユ−圧縮機 |
JPH05149287A (ja) * | 1991-11-26 | 1993-06-15 | Hitachi Ltd | パツケージ形スクリユー圧縮機 |
JPH06330875A (ja) * | 1993-05-19 | 1994-11-29 | Seiko Seiki Co Ltd | 排気ポンプ |
JPH09268993A (ja) * | 1996-04-02 | 1997-10-14 | Tochigi Fuji Ind Co Ltd | 流体機械 |
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DE19820523A1 (de) * | 1998-05-08 | 1999-11-11 | Peter Frieden | Schraubenspindel-Vakuumpumpe mit Rotorkühlung |
JPH11336684A (ja) * | 1998-05-22 | 1999-12-07 | Hitachi Ltd | オイルフリースクリュー圧縮機のジャケット冷却装置 |
DE10156179A1 (de) * | 2001-11-15 | 2003-05-28 | Leybold Vakuum Gmbh | Kühlung einer Schraubenvakuumpumpe |
-
2002
- 2002-10-14 GB GBGB0223769.1A patent/GB0223769D0/en not_active Ceased
-
2003
- 2003-10-10 KR KR1020057006340A patent/KR101120887B1/ko not_active IP Right Cessation
- 2003-10-10 AU AU2003271940A patent/AU2003271940A1/en not_active Abandoned
- 2003-10-10 WO PCT/GB2003/004415 patent/WO2004036049A1/en not_active Application Discontinuation
- 2003-10-10 US US10/531,558 patent/US20060153696A1/en not_active Abandoned
- 2003-10-10 JP JP2004544445A patent/JP2006503220A/ja active Pending
- 2003-10-10 EP EP03753778A patent/EP1552153A1/en not_active Withdrawn
- 2003-10-10 CN CNA2003801011997A patent/CN1703584A/zh active Pending
- 2003-10-14 TW TW092128450A patent/TW200422522A/zh unknown
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
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US2906448A (en) * | 1954-10-28 | 1959-09-29 | W C Heraus G M B H | Roots type vacuum pumps |
US4294402A (en) * | 1977-10-26 | 1981-10-13 | Honeywell Inc. | Control devices for heaters |
US4983107A (en) * | 1987-05-15 | 1991-01-08 | Leybold Aktiengesellschaft | Multistage rotary piston vacuum pump having sleeves to fix shaft positions |
US4983106A (en) * | 1988-10-07 | 1991-01-08 | Societe Anonyme Dite: Alcatel Cit | Rotary screw machine with multiple chambers in casing for lubrication-coding fluid |
US5040949A (en) * | 1989-06-05 | 1991-08-20 | Alcatel Cit | Two stage dry primary pump |
US5961291A (en) * | 1996-08-30 | 1999-10-05 | Hitachi, Ltd. | Turbo vacuum pump with a magnetically levitated rotor and a control unit for displacing the rotator at various angles to scrape deposits from the inside of the pump |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
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US20060269424A1 (en) * | 2005-05-27 | 2006-11-30 | Michael Henry North | Vacuum pump |
US20100229626A1 (en) * | 2005-12-15 | 2010-09-16 | Clive Marcus Lloyd Tunna | Apparatus for Detecting a Flammable Atmosphere Within a Compressor, in Particular a Vacuum Pump |
US8333573B2 (en) * | 2005-12-15 | 2012-12-18 | Edwards Limited | Apparatus for detecting a flammable atmosphere within a compressor, in particular a vacuum pump |
US20070145929A1 (en) * | 2005-12-21 | 2007-06-28 | Shimadzu Corporation | Vacuum pump |
US7417398B2 (en) * | 2005-12-21 | 2008-08-26 | Shimadzu Corporation | Vacuum pump |
US20170204860A1 (en) * | 2014-07-31 | 2017-07-20 | Edwards Japan Limited | Dry pump and exhaust gas treatment method |
US11592025B2 (en) * | 2014-07-31 | 2023-02-28 | Edwards Japan Limited | Dry pump and exhaust gas treatment method |
US10487834B2 (en) | 2015-09-15 | 2019-11-26 | Gree Electric Appliances, Inc. Of Zhuhai | Screw compressor and a compressor body thereof |
Also Published As
Publication number | Publication date |
---|---|
GB0223769D0 (en) | 2002-11-20 |
AU2003271940A1 (en) | 2004-05-04 |
KR20050050133A (ko) | 2005-05-27 |
JP2006503220A (ja) | 2006-01-26 |
CN1703584A (zh) | 2005-11-30 |
TW200422522A (en) | 2004-11-01 |
WO2004036049A1 (en) | 2004-04-29 |
EP1552153A1 (en) | 2005-07-13 |
KR101120887B1 (ko) | 2012-02-27 |
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