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
  • F04C18/08—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
  • F04C18/082—Details specially related to intermeshing engagement type pumps
  • F04C18/084—Toothed wheels

Definitions

• the invention relates to a pair of delivery screws for rotating positive displacement pumps, the delivery screws of which are designed as runners and counter-rotators rotate in the bore and in the flanks without contact at the same speed (screw pumps), form loss gaps between them and have the same depth, the same number of gears and have symmetrical flank profiles on both sides, each of which is composed of a tooth base below the flank profile reversal point and a tooth head above this flank profile reversal point with regard to their pitch.
• the volumetric and the overall efficiency are essentially influenced by the viscosity of the pumped medium and harmful gaps, the pressure height, however, depends on the bearing distance, the rotor length, the pitch of the rotor, its diameter and the hub ratio Nu (tooth root diameter: tooth tip diameter).
• the circumferential gap this is the gap between the rotor and the timewise rotor bore
• the basic gap this is the gap between the rotor outer diameter of one rotor and the root diameter of the other rotor
• the gaps between differentiate the flank profiles of the runners in the rotor engagement In the flank gap, a distinction is made between a gap to be specified for the required contact-free running and a profile-dependent gap which arises on account of the toothing laws. This profile-related loss gap is the subject of the present invention.
• Games are thereby increased, so that the effective flow rate drops after a short operating time.
• this problem is counteracted either by a plurality of closed chambers of the rotor arranged one behind the other, ie by increasing the number of chambers, or by different speeds of the counter-rotor.
• the first proposed solution leads to an extension of the rotor and thus to a large bearing distance and to a restriction of the delivery pressure as a result of the greater deflection.
• the runners have different number of gears and thus different speeds, which means that shorter filling times and, above all, larger viscosities prevent complete chamber filling.
• Another disadvantage is that if one runner has multiple gears, the smallest possible rotor pitch is in any case greater than that of the same-sized rotor pairs, since otherwise the tooth strength or gear strength would be too weak. This disadvantage also leads to a restriction of the suction height.
• the invention is based on the object of developing a pair of conveyor screws of the type described at the outset with the shortest possible rotor length and a correspondingly small length Bearing support spacing, with the smallest possible number of stages, large tooth tip width, small rotor pitch and small circumferential gap length, in order to create a screw pump with a relatively large delivery flow and high delivery pressure with low material consumption.
• This object is achieved in that the profile-related loss gap height in the axial section on the pitch circle is kept constant for a specific rotor diameter by shifting the flank profile reversal point as a function of a technically feasible rotor pitch.
• the rise in the flank profile reversal point begins from a minimum value that is greater than the pitch circle radius, and if the profile-related loss gap height to be kept constant in the axial section on the pitch circle in the range 0.1% to 1.5%, preferably 0 , 1% to 0.8% of the rotor diameter.
• the minimum flank profile reversal point is approximately 8/10 of the pitch circle radius plus 0.2.
• the profile reversal point should always have its optimum at the rotor end on the suction side and rise towards the rotor radius towards the rotor end on the pressure side. This is to dissipate the local heat generation on the pressure side through the profile-related gaps over the length of the rotor. The gap due to the profile is thus reduced towards the suction side.
• Figure 4 an axial section profile gap for q, ⁇ and q ⁇ ;
• FIG. 6 an axial section profile with a continuously variable profile generation circuit
• the screw spindle pump shown in FIGS. 7 and 8 has, as conveying elements, two pairs of opposing conveying screws which mesh with one another in a contactless manner and each comprise a right-handed conveying screw 1 and a left-handed conveying screw 2.
• the axial thrust is balanced by this two-flow arrangement.
• the pressure build-up is almost linear over the length of the conveyor elements.
• the medium flowing in or sucked in through the suction nozzle 5 of the pump is supplied to the two suction spaces in two partial flows in the pump housing 6.
• the torque is transmitted from the drive shaft to the driven shaft by means of a gear transmission 7 arranged outside the pump housing 6, the setting of which ensures the contact-free running of the conveying elements.
• a stuffing box is identified by reference 8.
• FIG. Figure 8 shows schematically the pressure port 10.
• the conveyor screw flanks are so straight designed as possible avoiding convex or concave shapes.
• the aim is to have a slight, gap-dependent loss gap.
• the inventive division of head and foot gaps taking into account the surface friction between the screw flanks at the same differential pressure, can significantly reduce the backflow loss, especially in the case of low-viscosity and high-gas media. This achieves an improvement in efficiency and less beam wear.
• the measure of compression heat is distributed in a targeted manner by the measure according to the invention and thus counteracts an exhaustion of the circumferential gap on the tooth head and running noises.
• a k Loss area at the tooth tip at the tooth engagement (in the face cut)
• a f t Loss area at the tooth base at the tooth engagement (in the face cut)
• a v Sum of the loss areas of the tooth tip and tooth root at
• Tooth engagement in the face cut

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Rotary Pumps (AREA)
• Details And Applications Of Rotary Liquid Pumps (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=6464331

Family Applications (1)

Country Status (10)

Families Citing this family (9)

Family Cites Families (4)

• 1992
  • 1992-07-29 DE DE4224969A patent/DE4224969C1/de not_active Expired - Fee Related
• 1993
  • 1993-07-03 WO PCT/DE1993/000595 patent/WO1994003730A1/fr active IP Right Grant
  • 1993-07-03 ES ES93914601T patent/ES2089828T3/es not_active Expired - Lifetime
  • 1993-07-03 JP JP6504876A patent/JPH07509295A/ja active Pending
  • 1993-07-03 EP EP93914601A patent/EP0653021B1/fr not_active Expired - Lifetime
  • 1993-07-03 AT AT93914601T patent/ATE139304T1/de not_active IP Right Cessation
  • 1993-07-03 CA CA002141455A patent/CA2141455A1/fr not_active Abandoned
  • 1993-07-22 ZA ZA935312A patent/ZA935312B/xx unknown
  • 1993-07-29 CN CN93116899A patent/CN1042259C/zh not_active Expired - Fee Related
• 1995
  • 1995-01-27 NO NO950310A patent/NO306076B1/no not_active IP Right Cessation

Non-Patent Citations (1)

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