EP1710436A1 - Internal gear pump - Google Patents

Internal gear pump Download PDF

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Publication number
EP1710436A1
EP1710436A1 EP04807610A EP04807610A EP1710436A1 EP 1710436 A1 EP1710436 A1 EP 1710436A1 EP 04807610 A EP04807610 A EP 04807610A EP 04807610 A EP04807610 A EP 04807610A EP 1710436 A1 EP1710436 A1 EP 1710436A1
Authority
EP
European Patent Office
Prior art keywords
rotor
outer rotor
casing
inner rotor
hole
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.)
Withdrawn
Application number
EP04807610A
Other languages
German (de)
English (en)
French (fr)
Inventor
Katsuaki Hosono
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Diamet Corp
Original Assignee
Mitsubishi Materials PMG Corp
Diamet Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Mitsubishi Materials PMG Corp, Diamet Corp filed Critical Mitsubishi Materials PMG Corp
Publication of EP1710436A1 publication Critical patent/EP1710436A1/en
Withdrawn legal-status Critical Current

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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
    • 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
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • 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
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/102—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member the two members rotating simultaneously around their respective axes
    • 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
    • F04C2230/00—Manufacture
    • F04C2230/60—Assembly methods
    • F04C2230/602—Gap; Clearance

Definitions

  • the present invention relates to an internal gear pump which draws and discharges fluid by changes in the volumes of cells formed between an inner rotor and an outer rotor when the inner rotor and the outer rotor rotate in engagement with each other.
  • an internal gear pump comprises an inner rotor having "n" external teeth, an outer rotor formed with “n+1” internal teeth which are engageable with the external teeth, and a casing in which a suction port for drawing fluid and a discharge port for discharging fluid are formed. Also, in a state in which the inner rotor and the outer rotor are accommodated in a hole formed in the casing, the inner rotor connected to a driving shaft is rotated, thereby rotating the outer rotor while the external teeth engage the internal teeth, so that fluid is drawn and discharged by changes in the volumes of a plurality of cells formed between the inner rotor and the outer rotor.
  • the cells are separately delimited at a front portion and at a rear portion as viewed in the direction of rotation of the inner and outer rotors by the external teeth of the inner rotor and the internal teeth of the outer rotor which contact each other, thereby forming independent fluid conveying chambers which is rotatably moved as the inner rotor rotates.
  • Each cell becomes the smallest in volume in the course of engagement between the external teeth and the internal teeth, and the cell is then increased in volume as it moves along the suction port, thereby drawing fluid through the suction port. Also, the cell having the largest volume is decreased in volume as it moves along the discharge port, thereby discharging fluid through the discharge port (refer to Japanese Patent No. 3293507 ).
  • the inner rotor and the outer rotor are disposed to have a predetermined eccentric distance therebetween, and the outer rotor is disposed coaxially with the hole of the casing.
  • a means for driving the internal gear pump includes a crankshaft directly-connected and driving method in which an inner rotor directly connected to a crankshaft of an engine is driven by the rotation of the engine.
  • the respective members of such an internal gear pump are dimensioned to have predetermined play when the gear pump is manufactured for the purpose of convenience of assembling or the like.
  • the internal diameter of a through-hole bored in a central portion of the inner rotor is set to be about 0.1 mm to 0.06 mm larger than the external diameter of the driving shaft loaded into the through-hole
  • the internal diameter of the hole formed in the casing is set to be about 0.1 mm to 0.6 mm larger than the external diameter of the outer rotor.
  • the outer rotor and the hole of the casing are disposed coaxially with each other, and a clearance of about 0.05 mm to 0.3 mm is set between an entire outer peripheral surface of the outer rotor and an inner peripheral surface of the hole formed in the casing.
  • the inner rotor when the internal gear pump constructed as above is driven, the inner rotor is rotated while being whirled by about 0.05 mm to 0.30 mm in its radial direction from an central axis of the driving shaft, and due to the clearance between the inner rotor and the driving shaft, the outer rotor is rotated while being whirled by about 0.05 mm to 0.3 mm in its radial direction from an central axis of the hole of the casing.
  • the external teeth of the inner rotor may collide against the internal teeth of the outer rotor, and the driving force received by the outer rotor at the time of this colliding may cause the outer peripheral surface of the outer rotor to further collide against the inner peripheral surface of the hole formed in the casing. Accordingly, noise may be generated when the internal gear pump is driven, and the pump efficiency may be deteriorated.
  • the present invention has been made in view of the above circumstances. Accordingly, it is an object of the present invention to provide an internal gear pump in which the sliding resistance of the internal gear pump can be reduced, and the occurrence of noise and a decrease in the pump efficiency can be suppressed to the minimum even in this construction.
  • the present invention proposes the following means.
  • the present invention provides an internal gear pump comprising: an inner rotor formed with "n" external teeth ("n” is a natural number); and an outer rotor formed with (n+1) internal teeth which are engageable with the external teeth, and a casing formed with a suction port for drawing fluid and a discharge port for discharging fluid.
  • the fluid is conveyed by drawing and discharging the fluid by changes in volumes of cells formed between tooth surfaces of the inner rotor and the outer rotor while the inner rotor and the outer rotor rotate in engagement with each other.
  • the internal diameter of a hole formed in the casing for accommodating the inner rotor and the outer rotor is set to be 0.1 mm to 0.6 mm larger than that the external diameter of the outer rotor.
  • the distance between the inner peripheral surface of the hole formed in the casing and the outer peripheral surface of the outer rotor at an engaging position where the volume of a cell which is defined when the external teeth of the inner rotor the internal teeth of the outer rotor rotate in engagement with each other is the smallest is suppressed to the minimum.
  • the outer rotor is restrained in the forward movement in the direction of rotation thereof, and moved along the inner peripheral surface of the hole of the casing, so that the distance of movement of the outer rotor toward the position opposite to the engaging position with respect to the rotation of center becomes small by the restrained distance of the outer rotor.
  • the occurrence of collision between the external teeth of the inner rotor and the internal teeth of the outer rotor at the opposite position can be suppressed.
  • the sliding resistance of the internal gear pump can be remarkably reduced, and the occurrence of noise and a decrease in the pump efficiency can be suppressed to the minimum even in this construction.
  • FIGS. 1 and 2 An internal gear pump according to an embodiment of the present invention will now be described with reference to FIGS. 1 and 2.
  • the internal gear pump shown in FIG. 1 generally comprises an inner rotor 10 formed with eight external teeth 11, an outer rotor 20 formed with nine internal teeth 21 which are engageable with the external teeth 11, and a casing 30 in which a suction port for drawing fluid and a discharge port for discharging fluid are formed.
  • the casing 30 is formed with a hole 31 which accommodates the inner rotor 10 and the outer rotor 20.
  • the illustration of the suction port and the discharge port are omitted in FIG. 1.
  • a through-hole 12 is bored in a radial central portion of the inner rotor 10.
  • the internal diameter of the inner rotor 10 is set to be about 0.1 mm to 0. 6 mm larger than the external diameter of a driving shaft loaded into the through-hole 12.
  • the driving shaft is directly connected to a crankshaft of an engine (not shown), so that the inner rotor 10 is supported so as to be rotatable about an axis O1 in the peripheral direction inside the casing 30 by the rotation of the engine. Accordingly, the axis O1 is the center of rotation of the through-hole 12 as well as the centers of rotation of the inner rotor 10 and the driving shaft.
  • the outer rotor 20 is disposed so that the internal teeth 21 are engageable with the external teeth 11 in a state that an axis 02 of the outer rotor is offset (eccentric distance er) from the axis O1 of the inner rotor 10, and is supported so as to be rotatable about the axis 02 in the peripheral direction inside the casing 30.
  • the external teeth 11 of the inner rotor 10 are formed so that the tooth profiles of tooth tips 11a thereof are formed based on an epicycloid curve which is generated by rolling a first circumscribed-rolling circle Ai along a first base circle Di without slip, and the tooth profiles of tooth spaces 11b thereof are formed based on an hypocycloid curve which is generated by rolling a first inscribed-rolling circle Bi along the first base circle Di without slip.
  • the internal teeth 21 of the outer rotor 20 are formed so that the tooth profiles of tooth tips 21a thereof are formed based on a hypocycloid curve which is generated by rolling a second inscribed-rolling circle Bo along a second base circle Do without slip, and the tooth profiles of tooth spaces 21b thereof are formed based on an epicycloid curve which is generated by rolling a second circumscribed-rolling circle Ao along the second base circle Do without slip.
  • e r ( d ⁇ D ) / 4
  • 'd' is the diameter of a circle obtained by sequentially connecting apexes of the tooth tips 11a of the respective external teeth 11 of the inner rotor 10 with each other, i.e., the larger diameter of the inner rotor
  • 'D' is the diameter of a circle obtained by sequentially connecting bottoms of the tooth spaces 11b of the respective external teeth 11 of the inner rotor 10 with each other, i.e., the smaller diameter of the inner rotor 10.
  • the inner rotor 10 and the outer rotor 20 are rotated by the rotation of the driving shaft while the tooth surfaces thereof engage each other.
  • Cells S serving as fluid conveying chambers are formed between engaging points of the inner rotor 10 and the outer rotor 20 which are engageable with each other.
  • the suction port and the discharge port opened to the cells S are formed in the casing 30, so that the exchange of fluid with the respective cells S through the suction port and the discharge port is performed.
  • the cells S are also rotatably moved to cause changes in the volumes of the cells, so that fluid is drawn through the suction port in the course of an increase in the volumes of the cells S, while fluid is discharged through the discharge port in the course of a decrease in the volumes of the cells S.
  • the casing 30 is formed with the hole 31 which accommodates the inner rotor 10 and the outer rotor 20, as previously mentioned.
  • the internal diameter of the hole 31 is set to be about 0.1 mm to 0.6 mm larger than the external diameter of the outer rotor 20.
  • the center 03 of the hole 31, as shown in FIG. 1, is located so that it is offset from the axis 02 of the outer rotor 20 by 0.005 mm to 0.030 mm, more preferably, 0.010 mm to 0.020 mm in a direction away from the axis O1 of the inner rotor 10 and the engaging position A with respect to the axis 02.
  • the engaging position A means a position where the rotational driving force from the inner rotor 10 is transmitted to the outer rotor 20.
  • a clearance t between an inner peripheral surface of the hole 31 of the casing 30 and an outer peripheral surface of the outer rotor 20 is gradually decreased from the engaging position A toward a peripheral position B offset by 180° forward or rearward in the direction of rotation from the position A so that a clearance tA is the largest at the engaging position A and a clearance tB is the smallest at the peripheral position B.
  • the clearance tA at the engaging position A is set to 0.020 mm to 0.295 mm
  • the clearance tB at the peripheral position B is set to 0.055 mm to 0.330 mm.
  • FIG. 1 the hole 31 of the casing 30 is shown in an enlarged state for the purpose of convenience of explanation.
  • Example 1 including data values related to the inner rotor 10, the outer rotor 20 and the casing 30, which are shown in FIG. 1, are shown in FIGS. 2A and 2B along with Comparative example 1 as a related art.
  • the larger diameter of the outer rotor means the diameter of a circle obtained by sequentially connecting the bottoms of the tooth spaces 21b of the respective internal teeth 21 with each other in the peripheral direction
  • the smaller diameter of the outer rotor means the diameter of a circle obtained by sequentially connecting the apexes of the tooth tips 21a of the respective internal teeth 21 with each other in the peripheral direction.
  • Example 1 Comparative example 1, it was noted herein that the internal diameter of the hole formed in the casing for accommodating the inner rotor and the outer rotor was set to 79.99 mm to 80.01 mm, and the external diameter of the outer peripheral surface of the outer rotor opposing the inner peripheral surface of the hole was set to 79.75 mm to 79.80 mm.
  • the eccentric distance er was calculated from the larger diameter d and the smaller diameter D of the inner rotor, that was, the tooth heights of the inner and outer rotors was 0.015 mm smaller as that in Comparative example 1 as a related art, whereby Example 1 could be realized.
  • the clearance tA between the inner peripheral surface of the hole 31 formed in the casing 30 and the outer peripheral surface of the outer rotor 20 could be suppressed to the minimum at the engaging position A where the external teeth 11 of the inner rotor 10 and the internal teeth 21 of the outer rotor 20 engaged each other to form the cell S having the smallest volume.
  • the outer rotor 20 was restrained in the forward movement in the direction of rotation thereof, and moved along the inner peripheral surface of the hole 31 of the casing 30, so that the distance of movement of the outer rotor 20 toward the peripheral position B offset by 180° from the engaging position A forward or rearward in the direction of rotation thereof became small by the restrained distance of the outer rotor, that was, the outer rotor 20 was biased to the peripheral position B.
  • the occurrence of collision between the external teeth 11 of the inner rotor 10 and the internal teeth 21 of the outer rotor 20 at the peripheral position B could be suppressed to the minimum.
  • Example 2 including data values according to the present invention in this case is shown in FIG. 3, along with Comparative example 2 as a related art. In Both Example 2 and Comparative example 2 shown in FIG.
  • the internal diameter of a hole formed in a casing for accommodating inner and outer rotors is set to 59.99 mm to 60.01 mm
  • the external diameter of an outer peripheral surface of the outer rotor opposing an inner peripheral surface of the hole is set to 59.80 mm to 59.85 mm
  • the number of teeth of the inner rotor is nine
  • the number of teeth of the outer rotor is ten. In this case, the same effects as the above embodiment can also be obtained.
  • the above embodiment has been described about the construction employing a crankshaft directly-connected and driving method in which the inner rotor 10 is connected to a driving shaft directly connected to a crankshaft of an engine, and is driven by the rotation of the engine.
  • the present invention is not limited thereto, and may be applied to, for example, an internal gear pump which employs a direct-current (DC) motor having a relatively small driving force as driving means, and which conveys fuel, such as light oil, having a relativity high viscosity.
  • DC direct-current
  • the above embodiment has been described about the construction in which the center 03 of the hole 31 of the casing 30 is disposed on a section of an extension line, which is obtained by connecting the axis 01 of the inner rotor 10 with the axis 02 of the outer rotor 20, located opposite to the axis 01 and the engaging position A with respect to the axis 02.
  • the present invention is not limited thereto.
  • the center 03 may be disposed on a section of the extension line opposite to the axis 01 and the engaging position A with respect to the axis 02 so that the angle formed between a straight line, which is obtained by connecting the axis O1 with the center 03, located on a circumference having a radius eh of the inner rotor 10 centered on the axis O1, and the extension line is O° to 30°.
  • the present invention it is possible to provide an internal gear pump in which the sliding resistance of the internal gear pump can be reduced, and the occurrence of noise and a decrease in the pump efficiency can be suppressed to the minimum even in this construction.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)
EP04807610A 2003-12-26 2004-12-22 Internal gear pump Withdrawn EP1710436A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2003435370A JP2005194890A (ja) 2003-12-26 2003-12-26 内接型ギヤポンプ
PCT/JP2004/019253 WO2005064163A1 (ja) 2003-12-26 2004-12-22 内接型ギアポンプ

Publications (1)

Publication Number Publication Date
EP1710436A1 true EP1710436A1 (en) 2006-10-11

Family

ID=34736633

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04807610A Withdrawn EP1710436A1 (en) 2003-12-26 2004-12-22 Internal gear pump

Country Status (5)

Country Link
EP (1) EP1710436A1 (ja)
JP (1) JP2005194890A (ja)
KR (1) KR20060129309A (ja)
CN (1) CN1902401A (ja)
WO (1) WO2005064163A1 (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9488172B2 (en) 2012-05-24 2016-11-08 GM Global Technology Operations LLC Pump assembly for a vehicle

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5444292B2 (ja) * 2011-07-06 2014-03-19 三菱電機株式会社 電動オイルポンプ
JP6027343B2 (ja) * 2012-06-01 2016-11-16 株式会社山田製作所 オイルポンプのロータ
US10815991B2 (en) * 2016-09-02 2020-10-27 Stackpole International Engineered Products, Ltd. Dual input pump and system
KR20170003666U (ko) 2017-09-26 2017-10-24 훌루테크 주식회사 용적 조절이 가능한 내접기어펌프

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3912965A1 (de) * 1989-04-20 1990-10-25 Bosch Gmbh Robert Aggregat zum foerdern von kraftstoff
JP3734617B2 (ja) * 1997-04-11 2006-01-11 三菱マテリアル株式会社 オイルポンプロータ
JPH10331777A (ja) * 1997-05-28 1998-12-15 Denso Corp 内接ギヤポンプ

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2005064163A1 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9488172B2 (en) 2012-05-24 2016-11-08 GM Global Technology Operations LLC Pump assembly for a vehicle

Also Published As

Publication number Publication date
WO2005064163A1 (ja) 2005-07-14
KR20060129309A (ko) 2006-12-15
CN1902401A (zh) 2007-01-24
JP2005194890A (ja) 2005-07-21

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