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
  • F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
  • F04C23/02—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
• • 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
  • F01C21/104—Stators; Members defining the outer boundaries of the working chamber
  • F01C21/106—Stators; Members defining the outer boundaries of the working chamber with a radial surface, e.g. cam rings
• • 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
  • F01C21/104—Stators; Members defining the outer boundaries of the working chamber
  • F01C21/108—Stators; Members defining the outer boundaries of the working chamber with an axial surface, e.g. side plates
• • 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
  • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
  • F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
  • F04C15/0007—Radial sealings for working fluid
  • F04C15/0019—Radial sealing elements specially adapted for intermeshing-engagement type machines or pumps, e.g. gear machines or 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
  • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
  • F04C15/0003—Sealing arrangements in rotary-piston machines or pumps
  • F04C15/0023—Axial sealings for working fluid
  • F04C15/0026—Elements specially adapted for sealing of the lateral faces of intermeshing-engagement type machines or pumps, e.g. gear machines or 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
  • F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
  • F04C15/06—Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
• • 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
  • F04C2/00—Rotary-piston machines or pumps
  • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
  • F04C2/12—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
  • F04C2/14—Rotary-piston machines or pumps 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
  • F04C2/18—Rotary-piston machines or pumps 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 similar tooth forms
• • 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
  • F04C2210/00—Fluid
  • F04C2210/14—Lubricant
• • 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
  • F04C2210/00—Fluid
  • F04C2210/40—Properties
  • F04C2210/44—Viscosity

Definitions

• the present invention relates to a pumping assembly for feeding oil under pressure to a user.
• the present invention relates to a pumping assembly of the type comprising a gear pump and an electric motor for actuating the gear pump itself.
• the gear pump comprises a pair of gears coupled to each other, each of which comprises a gear wheel with external teeth formed at an intermediate portion of a support shaft assembled so as to rotate around a rotation axis parallel to the rotation axis of the other gear wheel.
• the two gears are mounted in a pump body comprising a sleeve, which extends around the gear wheels, has a length substantially equal to the length of the gear wheels, and is closed axially by two side elements, which are mounted in contact with the end faces of the sleeve perpendicular to the rotation axes of the gears, are engaged in a rotary manner by said support shafts, and define, together with the sleeve itself, a containing chamber of the gear wheels.
• the containing chamber is limited internally by a pair of substantially cylindrical lateral surfaces, each of which extends around a respective gear wheel, is substantially coaxial with a respective rotation axis, and presents a concavity facing the other lateral surface.
• the torque delivered by the electric motor for actuating the gear pump depends on the outlet pressure of the oil from the gear pump, on the forces of mechanical friction generated between the gears, and on the forces of viscous friction generated in the oil advanced by the gears themselves.
• the forces of viscous friction are transmitted between layers of oil adjacent to each other and are proportional, for fluids such as oil, to the viscosity and to the shear rate of the oil in a direction perpendicular to said lateral surfaces.
• the shear rate and, therefore, the viscous friction forces present the maximum values in correspondence of the clearance present between the gears, that is to say the mobile elements of the gear pump, and the pump body, namely the fixed element of the gear pump itself.
• the oil viscosity increases with a decrease of the operating temperature of the pumping assembly and that the shear rate is relatively high since the gear wheels are substantially fluid-tight radially with the relative lateral surfaces and axially with the side elements so as to fluid-tight separate an oil inlet in the containing chamber from an outlet of the oil under pressure from the containing chamber itself.
• the known pumping assemblies of the type described above have several drawbacks, mainly due to the fact that the electric motor must be dimensioned to deliver a relatively high drive torque and is therefore relatively complex and expensive.
• the purpose of the present invention is to provide a pumping assembly for feeding oil under pressure to a user that is free from the drawbacks described above and which is of simple and inexpensive implementation.
• a pumping assembly for feeding oil under pressure to a user as claimed in the appended claims.
• Figure 1 is a schematic perspective view of a preferred embodiment of the pumping assembly of the present invention
• Figures 2 and 3 are two schematic perspective views of a detail of the pumping assembly of Figure 1;
• Figure 4 is a schematic cross section, with parts removed and parts enlarged for clarity, of the detail of Figures 2 and 3.
• a pumping unit which is adapted to draw oil from a containing tank (not shown) at atmospheric pressure and to feed oil under pressure to a user (not shown) , for example, a user of the automotive sector, and comprises a gear pump 2, in this case a pump with external gears, substantially immersed in said containing tank (not shown) and an electric motor 3 for actuating the pump 2 itself.
• the pump 2 is provided with a pair of gears 4 coupled to each other, each of which comprises a support shaft 5 presenting a longitudinal axis 6 parallel to axis 6 of the other gear 4, and an externally toothed gear wheel 7, which is formed at an intermediate portion of the shaft 5, and has a plurality of teeth 8 equally spaced about axis 6.
• the gear wheels 4 are mounted in a pump body 9 comprising a sleeve 10, which extends around the gear wheels 7, presenting a length, measured parallel to axes 6, substantially equal to the length of gear wheel 7, also measured parallel to the axes 6, and is limited internally by a shaped lateral wall 11.
• the wall 11 defines two lateral surfaces 12, each of which has, in this case, a substantially cylindrical shape with concavity facing the other surface 12, extends around a respective gear wheel 7, and presents a longitudinal axis 13, which is parallel to the relative axis 6, is distinguished from relative axis 6, and is arranged at a distance from the axis 13 of the other surface 12 less than the sum of the radii of curvature of the two surfaces 12.
• each surface 12 is wound in a spiral around the relative gear wheel 7 from one of its ends 14 substantially tangent to the gear wheel 7 itself so that the radial distance Dr between the surface 12 and the relative teeth 8 increases progressively in the direction of rotation of the relative gear 4.
• each surface 12 is wound around teeth 8 of the respective gear wheel 7 according to a profile different from that described and illustrated in Figure 4, and presents, for example, downstream of the end 14, a constant radial distance Dr from teeth 8 themselves .
• the sleeve 10 is closed axially by two substantially flat closing plates 15, which are mounted on opposite sides of the sleeve 10 perpendicularly to axes 6, are engaged in a rotary manner by the shafts 5, each being limited axially by a respective flat lateral surface 16 facing the sleeve 10, and are locked against the end faces of the sleeve 10 to define, together with the sleeve 10 itself, a containing chamber 17 of the gear wheels 7.
• the chamber 17 comprises an area 18 of low pressure hydraulically connected with said containing tank (not shown) of the oil through a suction conduit 19 formed radially through the sleeve 10, and an area 20 of high pressure, which is separated in a substantially fluid-tight manner from the area 18, and is hydraulically connected with said user (not shown) by a delivery conduit 21 formed in part through the sleeve 10 and in part through one of the plates 15 parallel to axes 6.
• Each plate 15 has an elongated cavity 22, which opens towards the outside in correspondence with the relative surface 16, presents a substantially ⁇ shape, and comprises two sections 23 connected to each other, each of which presents a substantially circular shape, is facing axially to the teeth 8 of a relative gear wheel 7, extends around relative axis 6 substantially at the area 20 of high pressure, and is limited by a bottom wall 24 arranged at a substantially constant axial distance Da from the teeth 8 of the relative gear wheel 7.
• each section 23 may present a profile and an axial distance from the teeth 8 of the relative gear wheel 7 different from those described and illustrated in Figures 2 and 3;
• each plate 15 is eliminated and replaced with two cavities separated from each other and each facing the teeth 8 of the relative gear wheel 7.
• the presence of a free radial space between the teeth 8 of each gear wheel 7 and the relative surface 12 and of a free axial space between the teeth 8 of each gear wheel 7 and the two cavities 22 allow to reduce the shear rates present between the gear wheels 7, i.e. the mobile elements of the pump 2, and the sleeve 10 and the plates 15, i.e. the fixed elements of the pump 2 itself.
• the reduction of shear rates results in the reduction of the frictional forces of a viscous type, which are, consequently, relatively small even at relatively low operating temperatures, i.e. at operating temperatures to which the oil viscosity is relatively high.
• the operation of the pump 2 requires, therefore, a relatively low driving torque even at relatively low operating temperatures and allows the use of relatively simple and inexpensive electric motors 3.
• the external gear pump 2 is eliminated and replaced with an internal gear pump comprising a pump body, inside which are housed an internally toothed crown wheel and an externally toothed gear wheel, which presents an outer diameter smaller than the inner diameter of the crown wheel, is mounted inside of the crown wheel, and is coupled with the crown wheel itself.
• the internal gear pump further comprises at least one filling body, which is mounted inside the pump body between the crown wheel and the gear wheel, and is limited by two lateral surfaces, which are radially facing the teeth of the crown wheel and, respectively, to the teeth of the gear wheel, and present respective ends substantially tangent to the crown wheel and, respectively, to the gear wheel.
• the two lateral surfaces are wrapped helically from their ends around the crown wheel and, respectively, to the gear wheel so that the radial distance Dr between the lateral surfaces and the relative teeth increases in the direction of rotation of the crown wheel and, respectively, of the gear wheel.
• the pump body of the internal gear pump can be closed axially by two closing plates similar to the plates 15.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Rotary Pumps (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=43975262

Family Applications (1)

Country Status (5)

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Citations (1)

Family Cites Families (11)

• 2011
  • 2011-01-25 IT ITBO2011A000025A patent/IT1403528B1/it active
• 2012
  • 2012-01-25 EP EP12707908.5A patent/EP2668371A2/fr not_active Withdrawn
  • 2012-01-25 WO PCT/IB2012/050350 patent/WO2012101588A2/fr not_active Ceased
  • 2012-01-25 US US13/981,678 patent/US20140037473A1/en not_active Abandoned
  • 2012-01-25 CN CN2012800064939A patent/CN103443401A/zh active Pending

Patent Citations (1)

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