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
  • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
  • F04C18/30—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
  • F04C18/34—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members
  • F04C18/344—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
  • F04C18/3441—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation
• • 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
  • F04C29/12—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
  • F04C29/124—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps
• • 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
  • F04C29/12—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
  • F04C29/124—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps
  • F04C29/126—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps of the non-return 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
  • F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
  • F04C29/12—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
  • F04C29/124—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps
  • F04C29/126—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps of the non-return type
  • F04C29/128—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet with inlet and outlet valves specially adapted for rotary or oscillating piston pumps of the non-return type of the elastic type, e.g. reed valves

Definitions

• the present invention relates to rotary pumps, and more specifically it concerns a safety valve for a rotary pump.
• the invention is applied in the so-called single-vane pumps, i.e. pumps where the rotor includes a single vane with constant length, and the following description will mainly refer to this preferred application.
• Single-vane pumps are often used as vacuum pumps, for instance in the automotive field. They comprise a body defining a chamber, for instance with approximately elliptical cross section, in which the rotor rotates, substantially in tangential contact, about an eccentric axis.
• the rotor has a diametrical slot where the vane is mounted and the vane is radially movable in the slot so that, while the rotor is rotating, the vane ends slide substantially in contact with the internal wall of the chamber.
• the chamber is divided by the rotor and the vane into a suction room and a pressure room, between which a pumped fluid is displaced.
• a problem that can arise in known rotary pumps is due to the presence of oil within the pump, which takes place for instance if the suction valve(s) do(es) not have a perfect seal or, when the engine is stopped, because of oil suction into the pump.
• the phenomenon of oil suction may be due to the permanence of a depression inside the pump for relatively short but significant periods, occurring when the engine is turned off: such oil, if it is not discharged, can give rise to problems at the cold start of the engine.
• Document EP 1890040 discloses an example of rotary vacuum pump having a safety valve with a movable, swivelling vane, a bypass connection and a tank for storage of the residual oil.
• the safety valve is an additional valve that can be combined with the discharge valve of the pump.
• pumps are known in which an opening is formed for discharging, through a one-way valve, fluid that has been sucked or is any case present inside them.
• the safety valve is usually coaxially formed with the rotation axis of the rotor and directly discharges the fluid into the support onto which the pump is flanged.
• the flow area of the discharged fluid is insufficient to ensure the discharge of the fluid when the latter mainly consists of a liquid that is very dense by its nature or whose density has increased because of the low temperature.
• this is achieved by means of a rotary pump comprising an interspace formed within the pump housing near the area of tangency between the rotor and the internal wall of the pumping chamber.
• the interspace communicates with the pumping chamber through the discharge outlet of a safety valve and is connected to a discharge duct arranged to discharge the fluid outside the pumping chamber.
• the discharge outlet is formed with a radial opening relative to the axis of the pumping chamber and radially discharges the fluid.
• the invention also provides a method of operating a rotary pump, comprising a discharge step in which the fluid to be compressed is discharged from the safety valve in a radial direction relative to the axis of the pumping chamber through the discharge outlet
• Fig. 1 is a plan view of a rotary pump with a safety valve according to the invention, without the cover and with the valve region being shown partially in cross-section;
• FIG. 2 is a cross-sectional view of a rotary pump with the safety valve according to the invention, without the rotor and the vane.
• a pump 50 includes a housing 40 defining a pumping chamber 15, for instance with approximately elliptical cross section, having an internal wall 42.
• Chamber 15 accommodates a rotor 18 that, in known manner, rotates in substantially tangential contact with said internal wall 42 in correspondence of an area of tangency 17.
• the rotor has a radial slot in which a vane 22, radially slidable within the same slot, is mounted.
• the vane and the rotor divide chamber 15 into a suction chamber 33, into which a fluid to be compressed is sucked, and a compression chamber 38 in which the fluid is compressed.
• Pump 50 further comprises a suction duct 10, ending into suction chamber 33, through the suction valve of known type (not shown) from which the fluid to be compressed is sucked, and a discharge duct 16, which ends into compression chamber 38 through the discharge valve of known type (not shown) and is arranged to discharge the fluid outside pumping chamber 15.
• the vacuum pump according to the invention shown in Figs. 1 and 2 includes a safety valve 20, formed in the internal wall 42 near the area of tangency 17 between rotor 18 and internal wall 42 and adapted to discharge a residual fluid, e.g. oil remained within pumping chamber 15, outside the chamber.
• a safety valve 20 formed in the internal wall 42 near the area of tangency 17 between rotor 18 and internal wall 42 and adapted to discharge a residual fluid, e.g. oil remained within pumping chamber 15, outside the chamber.
• Safety valve 20 includes a discharge outlet 11, 12 formed in pumping chamber 15 in a zone adjacent to the area of tangency 17 between rotor 18 and internal wall 42 of the chamber.
• Discharge outlet 11, 12 puts pumping chamber 15 in communication with an interspace 35 formed within housing 40, and it is formed with a radial opening relative to the axis of pumping chamber 15.
• safety valve 20 includes a first discharge outlet 11 formed in suction chamber 33, preferably in a zone of internal wall 42 between the inlet of suction duct 10 and the area of tangency 17.
• safety valve 20 further includes a second discharge outlet 12 formed in compression chamber 38, preferably in a zone of internal wall 42 between the inlet of the discharge valve and the area of tangency 17. Both discharge outlets end into discharge duct 16.
• the first discharge outlet 11 and the second discharge outlet 12 can put suction chamber 33 and compression chamber 38, respectively, in communication with interspace 35.
• Interspace 35 in turn is permanently connected to discharge duct 16 adapted to discharge the fluid, e.g. the residual fluid discharged from pumping chamber 15 through safety valve 20, outside interspace 35.
• Discharge outlets 11, 12 are radial openings relative to the axis of pumping chamber 15, and they are formed on internal wall 42 of chamber 15 in the region of tangency between rotor 18 and internal wall 42, in correspondence of the suction and discharge regions.
• Outlets 11, 12 are closed by a flexible or rigid lamina 13 mounted in abutment against the internal wall of interspace 35.
• Lamina 13 is made of metal, e.g. spring steel in case of a flexible lamina and steel sheet in case of rigid lamina, or of a composite polymer such as Kevlar, or of carbon fibres, and is shaped in known manner so as to ensure the closure of outlets 11, 12.
• Lamina 13 is maintained in abutment against the internal wall of interspace 35 by a spring 14, for instance a leaf spring 14 articulated in a seat 19 formed on the external wall of interspace 35.
• lamina 13 is maintained in abutment by two leaf springs.
• lamina 13 is maintained in abutment by only one spring, located between the first discharge outlet 11 and the second discharge outlet 12.
• the invention also concerns a method of operating a rotary pump 50 connectable to a thermal engine, said pump 50 comprising: a pumping chamber 15; a rotor 18 adapted to rotate substantially tangentially to an internal wall 42 of said pumping chamber 15; a vane 22 mounted radially slidable within a slot formed in rotor 18; a safety valve 20 formed in the internal wall 42 and having a discharge outlet 11, 12 formed with a radial opening relative to the axis of pumping chamber 15; said pumping chamber 15 being divided by vane 22 and rotor 18 into a suction chamber 33 and a compression chamber 38; said method comprising the following steps occurring twice at each revolution of the rotor: 1) a suction step, in which the fluid to be compressed is sucked into suction chamber 33;
• the first discharge outlet 11 of safety valve 20 opens due to the action of the pressurised fluid that displaces lamina 13 by overcoming the force exerted by leaf spring 14, thereby allowing the fluid to be discharged into interspace 35 and hence into discharge duct 16.
• the second discharge outlet 12 of safety valve 20 can operate in two different modes.
• leaf spring 14 is so constructed as to make the second discharge outlet 12 open at the normal discharge pressures.
• the valve increases the amount of fluid being discharged through the discharge duct both under the normal operating conditions and in case of cold start at low temperature in the presence of liquid made very dense because of the temperature in the compression chamber.
• leaf spring 14 is so constructed as to make the second discharge outlet 12 open at pressures higher than the normal discharge pressures.
• the valve increases the amount of fluid being discharged through the discharge duct only in case of cold start at low temperature in the presence of liquid in the compression chamber, thereby saving the pump integrity.
• safety valve 20 in both operating manners, having radial discharge outlets 11, 12 with large areas, located close to and spanning the area of tangency between rotor 18 and housing 40, allows having very wide flow areas for the fluid to be discharged.
• safety valve 20 thanks to the provision of interspace 35, allows forming discharge duct 16 connected to the interspace in the region of housing 40 that is the most suitable for accommodating said duct, thereby allowing keeping wide discharge cross sectional areas over the whole path from discharge outlets 11, 12 to discharge duct 16.
• the rotary pump with safety valve according to the invention allows making a device having a simplified structure and occupying a reduced space in comparison with the known pumps.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Applications Or Details Of Rotary Compressors (AREA)
• Rotary Pumps (AREA)
• Massaging Devices (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=50159451

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Family Cites Families (6)

• 2013
  • 2013-12-30 IT IT001083A patent/ITTO20131083A1/it unknown
• 2014
  • 2014-12-23 EP EP14830728.3A patent/EP3090184B1/de active Active
  • 2014-12-23 WO PCT/IB2014/067269 patent/WO2015101904A1/en not_active Ceased

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