JP3753073B2 - Permanent magnet rotating electric machine - Google Patents

Permanent magnet rotating electric machine Download PDF

Info

Publication number
JP3753073B2
JP3753073B2 JP2002010951A JP2002010951A JP3753073B2 JP 3753073 B2 JP3753073 B2 JP 3753073B2 JP 2002010951 A JP2002010951 A JP 2002010951A JP 2002010951 A JP2002010951 A JP 2002010951A JP 3753073 B2 JP3753073 B2 JP 3753073B2
Authority
JP
Japan
Prior art keywords
permanent magnet
spider
electromotive force
core
induced electromotive
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.)
Expired - Fee Related
Application number
JP2002010951A
Other languages
Japanese (ja)
Other versions
JP2003219586A (en
Inventor
守 木村
春雄 小原木
浩幸 三上
身佳 高橋
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.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP2002010951A priority Critical patent/JP3753073B2/en
Publication of JP2003219586A publication Critical patent/JP2003219586A/en
Application granted granted Critical
Publication of JP3753073B2 publication Critical patent/JP3753073B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Landscapes

  • Permanent Field Magnets Of Synchronous Machinery (AREA)
  • Iron Core Of Rotating Electric Machines (AREA)
  • Permanent Magnet Type Synchronous Machine (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、永久磁石式回転電機に関する。
【０００２】
【従来の技術】
従来、永久磁石式回転電機の永久磁石の表面磁束を有効に活用する構造として、特開２０００−１５２５３４号公報（以下引例１と称す）には、永久磁石を放射状に配置し、回転子鉄心の外径を磁極の中心で大きく、磁極と磁極の境で小さくし、回転子鉄心と軸の間に非磁性体を介在させたものが記載されている。また、回転子の径が大きい場合には、スパイダ構造を用いる。特開平１０−174325号公報（以下引例２と称す）には、スパイダに永久磁石及び、非磁性の極間スペーサ，非磁性の側面保護部材と外周保護部材で構成された回転子が記載されている。
【０００３】
【発明が解決しようとする課題】
永久磁石式回転電機では、永久磁石を放射状に配置することにより、磁石の磁束を有効に使うことができ、磁石量の低減を図ることができ、回転電機を小型軽量化することができる。しかしながら、軸が磁性体の場合では、軸に磁束が流れてしまうため特性が低下してしまう。そのため引例１では回転子鉄心と軸の間に非磁性体を介在させている。しかしながら、軸は磁性体のため、非磁性体を厚くしなければならないという問題がある。また、回転子鉄心を大径化し、スパイダを用いることにより非磁性体の厚さを低減することも可能であるが、磁性体であるスパイダの取り付け位置によっては、スパイダを磁束が通ってしまうため、回転電機の特性が低下してしまう問題がある。
【０００４】
【課題を解決するための手段】
以上の点に鑑み本発明は、永久磁石式回転電機において、強度を保ちつつ、非磁性体の厚さを低減し、磁石の磁束を有効に活用でき、小型軽量化を図ることができる永久磁石式回転電機を提供する。
【０００５】
本発明の特徴は、固定子鉄心のティースに巻線を施した固定子と、永久磁石を回転子鉄心に放射状に埋め込んだ回転子を備えた永久磁石式回転電機において、回転軸から伸びるスパイダを磁極下に設けることにある。
【０００６】
【発明の実施の形態】
以下、本発明の実施例を、図面を参照して説明する。
【０００７】
図１に、３０極の永久磁石式回転電機に適用した第１実施例につき回転子軸方向断面を示した図である。回転子１０は、回転軸１１から伸びるスパイダ１２に非磁性体１３を接合し、非磁性体１３上部に回転子鉄心１４を嵌合固着し、この回転子鉄心１４に放射状に形成された永久磁石挿入孔１５に、永久磁石１６を軸方向から、着磁方向１７のように、隣り合う永久磁石１６のＮ極とＳ極とが向かい合うように３０個挿入し、組込むことによって構成され、固定子２０の内部に固定子ティース先端部２１とギャップ２２を有する状態で回転可能に配置されている。固定子ティース２３の間にはスロット２４があり、ここには図示されていないが、スロット２４には三相の分布巻巻線、あるいは固定子ティース２３に集中的に巻かれた三相の集中巻巻線が配置される。
【０００８】
図２は、第１実施例につき、回転子１０を拡大して示したものである。スパイダ１２は、磁極２５の下部に配置されている。このスパイダ１２の位置は、永久磁石１６の非磁性体１３側の中心をｍｃ１，ｍｃ２で表し、このｍｃ１，ｍｃ２の距離をｄ１とし、ｍｃ１からスパイダ１２の非磁性体１３側の中心ｐまでの距離をｄ２としたとき、スパイダ位置係数Ｃｐを用いてｄ２＝Ｃｐ・ｄ１となるように設定する。第１実施例においてはＣｐ＝０.５となる。
【０００９】
また、非磁性体１３の厚さをｔ１，回転子鉄心１４の厚さをｔ２で表している。
【００１０】
図３は、比較例１として、スパイダ１２を永久磁石１６下部、すなわちＣｐ＝０あるいはＣｐ＝１の位置に設けた回転子３０を拡大して示したものである。図２と図３を用いて本発明の効果を説明すると、比較例１のようにスパイダ１２を永久磁石１６下部に設けると、永久磁石１６から発生する磁束はスパイダ１２を通るため、漏れ磁束が増え、誘導起電力の実効値が低下する。しかしながら、第１実施例のように、スパイダ１２を磁極２５下部に設けることにより、永久磁石１６から発生する磁束はスパイダ１２を通り難くなるため、漏れ磁束が減少し、誘導起電力の実効値が増加することとなる。誘導起電力の実効値により、回転電機の体格を決定するため第１実施例の構造とすることにより、回転電機を小型軽量化することができる。
【００１１】
図４は、縦軸を誘導起電力値とし、横軸を回転子位置（電気角で表示）としてスパイダ１２を磁極２５下部に設けた第１実施例の誘導起電力波形４１と、比較例１としてスパイダ１２を永久磁石１６下部に設けた場合の誘導起電力波形４２を示す。スパイダの取り付け位置により、誘導起電力の実効値が変化していることがわかる。誘導起電力波形４１の実効値は３７６.３Ｖ であり、誘導起電力波形４２の実効値は３１１.９Ｖ であるため、スパイダ１２を磁極２５下部に設けることにより、誘導起電力の実効値を約１.２ 倍することができる。
【００１２】
図５は、縦軸を誘導起電力値とし、横軸を厚さ係数Ｃとしてスパイダ１２を磁極２５下部に設けた第１実施例の効果５１と比較例１の効果５２を示す。ここで、前記非磁性体の厚さｔ１と前記回転子鉄心の厚さｔ２を用いてｔ１＝Ｃ・ｔ２と表したとき同図より、厚さ係数Ｃが０.８ 以下において第１実施例と比較例１の誘導起電力に差が生じており、厚さ係数Ｃ＝０.０４ において第１実施例の誘導起電力は３７５.０Ｖ であり、比較例１の誘導起電力２６３.３Ｖの１.４２倍とすることができる。但し、非磁性体の厚さｔ１は製作限界を考慮し１mm以上とする。
【００１３】
図６は、縦軸を誘導起電力値とし、横軸をスパイダ位置係数Ｃｐとして、第１実施例においてスパイダ位置を変化させた場合の効果６１を示す。同図より
０.１６７≦Ｃｐ≦０.８３３の範囲では、誘導起電力値がＣｐ＝０あるいはＣｐ＝１と比較して約１割高い。そのためスパイダ位置係数Ｃｐは０.１６７≦Ｃｐ≦０.８３３と設定することが望ましい。さらに、Ｃｐ≒０.５(０.４≦Ｃｐ≦
０.６）に設定すると最も誘導起電力値が高くなる。
【００１４】
【発明の効果】
本発明によれば、永久磁石式回転電機において、磁石の磁束を有効に活用でき、小型軽量化できる。
【図面の簡単な説明】
【図１】本発明の第１実施例の永久磁石式回転電機における主要断面の概略を示す図。
【図２】図１の部分拡大図。
【図３】本発明の比較例の部分拡大図。
【図４】本発明の第１実施例の効果を示す図。
【図５】本発明の第１実施例の効果を示す図。
【図６】本発明の第１実施例の効果を示す図。
【符号の説明】
１０，３０…回転子、１１…回転軸、１２…スパイダ、１３…非磁性体、１４…回転子鉄心、１５…永久磁石挿入孔、１６…永久磁石、２０…固定子、２１…固定子ティース先端部、２２…ギャップ、２５…磁極。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a permanent magnet type rotating electrical machine.
[0002]
[Prior art]
Conventionally, as a structure for effectively utilizing the surface magnetic flux of a permanent magnet of a permanent magnet type rotating electrical machine, Japanese Patent Laid-Open No. 2000-152534 (hereinafter referred to as Reference 1) arranges permanent magnets radially, The outer diameter is made large at the center of the magnetic pole, made small at the boundary between the magnetic poles, and a nonmagnetic material is interposed between the rotor core and the shaft. Further, when the rotor has a large diameter, a spider structure is used. Japanese Patent Laid-Open No. 10-174325 (hereinafter referred to as Reference 2) describes a spider that includes a permanent magnet, a nonmagnetic inter-electrode spacer, a nonmagnetic side surface protection member and an outer periphery protection member. Yes.
[0003]
[Problems to be solved by the invention]
In the permanent magnet type rotating electrical machine, by arranging the permanent magnets radially, the magnetic flux of the magnet can be used effectively, the amount of magnets can be reduced, and the rotating electrical machine can be reduced in size and weight. However, when the shaft is made of a magnetic material, the magnetic flux flows through the shaft, so that the characteristics are degraded. For this reason, in Reference 1, a nonmagnetic material is interposed between the rotor core and the shaft. However, since the shaft is magnetic, there is a problem that the nonmagnetic material must be thickened. Although it is possible to reduce the thickness of the non-magnetic material by increasing the diameter of the rotor core and using a spider, magnetic flux passes through the spider depending on the attachment position of the spider, which is a magnetic material. There is a problem that the characteristics of the rotating electrical machine deteriorate.
[0004]
[Means for Solving the Problems]
In view of the above points, the present invention provides a permanent magnet that can reduce the thickness of a non-magnetic material, effectively use the magnetic flux of a magnet, and can be reduced in size and weight while maintaining strength. A rotating electric machine is provided.
[0005]
A feature of the present invention is that a spider extending from a rotating shaft is provided in a permanent magnet type rotating electrical machine including a stator in which teeth of a stator core are wound and a rotor in which permanent magnets are radially embedded in the rotor core. It is to be provided under the magnetic pole.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0007]
FIG. 1 is a view showing a cross section in the rotor axial direction of a first embodiment applied to a 30-pole permanent magnet type rotating electrical machine. In the rotor 10, a non-magnetic body 13 is joined to a spider 12 extending from a rotating shaft 11, and a rotor core 14 is fitted and fixed on the non-magnetic body 13. A permanent magnet formed radially on the rotor core 14. 30 permanent magnets 16 are inserted into the insertion hole 15 from the axial direction so that the N and S poles of adjacent permanent magnets 16 face each other, as in the magnetizing direction 17, and are assembled. In the state which has the stator teeth front-end | tip part 21 and the gap 22 in the inside of 20, it is arrange | positioned rotatably. There is a slot 24 between the stator teeth 23, which is not shown here, but the slot 24 has a three-phase distributed winding, or a three-phase concentration concentrated around the stator teeth 23. Windings are arranged.
[0008]
FIG. 2 is an enlarged view of the rotor 10 according to the first embodiment. The spider 12 is disposed below the magnetic pole 25. The position of the spider 12 is represented by mc1 and mc2 at the center of the permanent magnet 16 on the nonmagnetic body 13 side, and the distance between the mc1 and mc2 is d1, and from the mc1 to the center p of the spider 12 on the nonmagnetic body 13 side. When the distance is d2, the spider position coefficient Cp is used so that d2 = Cp · d1. In the first embodiment, Cp = 0.5.
[0009]
Further, the thickness of the nonmagnetic material 13 is represented by t1, and the thickness of the rotor core 14 is represented by t2.
[0010]
FIG. 3 is an enlarged view of the rotor 30 provided with the spider 12 at the lower portion of the permanent magnet 16, that is, at a position of Cp = 0 or Cp = 1, as Comparative Example 1. The effects of the present invention will be described with reference to FIGS. 2 and 3. When the spider 12 is provided below the permanent magnet 16 as in the first comparative example, the magnetic flux generated from the permanent magnet 16 passes through the spider 12, so that the leakage flux is reduced. The effective value of the induced electromotive force decreases. However, by providing the spider 12 below the magnetic pole 25 as in the first embodiment, the magnetic flux generated from the permanent magnet 16 becomes difficult to pass through the spider 12, so that the leakage magnetic flux is reduced and the effective value of the induced electromotive force is reduced. Will increase. By adopting the structure of the first embodiment in order to determine the physique of the rotating electrical machine based on the effective value of the induced electromotive force, the rotating electrical machine can be reduced in size and weight.
[0011]
FIG. 4 shows the induced electromotive force waveform 41 of the first embodiment in which the vertical axis is the induced electromotive force value, the horizontal axis is the rotor position (displayed in electrical angle), and the spider 12 is provided below the magnetic pole 25, and Comparative Example 1. The induced electromotive force waveform 42 when the spider 12 is provided below the permanent magnet 16 is shown. It can be seen that the effective value of the induced electromotive force varies depending on the spider mounting position. Since the effective value of the induced electromotive force waveform 41 is 376.3V and the effective value of the induced electromotive force waveform 42 is 311.9V, the effective value of the induced electromotive force is reduced by providing the spider 12 below the magnetic pole 25. Can be multiplied by 1.2.
[0012]
FIG. 5 shows the effect 51 of the first embodiment and the effect 52 of the comparative example 1 in which the vertical axis is the induced electromotive force value, the horizontal axis is the thickness coefficient C, and the spider 12 is provided below the magnetic pole 25. Here, when the thickness t1 of the non-magnetic material and the thickness t2 of the rotor core are used to express t1 = C · t2, the first embodiment with a thickness coefficient C of 0.8 or less is shown in FIG. There is a difference between the induced electromotive force of Comparative Example 1 and the induced electromotive force of the first example is 375.0 V at a thickness coefficient C = 0.04, and the induced electromotive force of Comparative Example 1 is 263.3 V. It can be 1.42 times. However, the thickness t1 of the nonmagnetic material is set to 1 mm or more in consideration of the manufacturing limit.
[0013]
FIG. 6 shows the effect 61 when the spider position is changed in the first embodiment, with the vertical axis representing the induced electromotive force value and the horizontal axis representing the spider position coefficient Cp. From the figure, in the range of 0.167 ≦ Cp ≦ 0.833, the induced electromotive force value is about 10% higher than Cp = 0 or Cp = 1. Therefore, it is desirable to set the spider position coefficient Cp as 0.167 ≦ Cp ≦ 0.833. Furthermore, Cp≈0.5 (0.4 ≦ Cp ≦
When set to 0.6), the induced electromotive force value becomes the highest.
[0014]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, in a permanent magnet type rotary electric machine, the magnetic flux of a magnet can be utilized effectively and it can reduce in size and weight.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a main cross section of a permanent magnet type rotating electric machine according to a first embodiment of the present invention.
FIG. 2 is a partially enlarged view of FIG.
FIG. 3 is a partially enlarged view of a comparative example of the present invention.
FIG. 4 is a diagram showing the effect of the first embodiment of the present invention.
FIG. 5 is a diagram showing the effect of the first embodiment of the present invention.
FIG. 6 is a diagram showing the effect of the first embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10,30 ... Rotor, 11 ... Rotating shaft, 12 ... Spider, 13 ... Nonmagnetic material, 14 ... Rotor core, 15 ... Permanent magnet insertion hole, 16 ... Permanent magnet, 20 ... Stator, 21 ... Stator teeth Tip, 22 ... gap, 25 ... magnetic pole.

Claims (2)

固定子鉄心のティースに巻線を施した固定子と、放射状に配置された永久磁石挿入孔と回転軸とを有する回転子鉄心と、前記永久磁石挿入孔に埋め込まれた永久磁石と、前記回転子鉄心の前記回転軸側に配置された非磁性体とを有し、前記回転軸から伸びるスパイダが前記永久磁石間下部に配置され、前記永久磁石の前記非磁性体側の中心をｍｃ１，ｍｃ２とし、このｍｃ１，ｍｃ２の距離をｄ１とし、ｍｃ１から前記スパイダの前記非磁性体側の中心ｐまでの距離をｄ２とし、スパイダ位置係数Ｃｐを用いてｄ２＝Ｃｐ・ｄ１と表したとき、スパイダ位置係数ＣｐをＣｐ≒０.５ としたことを特徴とする永久磁石式回転電機。 A stator in which teeth of the stator core are wound, a rotor core having a radially arranged permanent magnet insertion hole and a rotation shaft, a permanent magnet embedded in the permanent magnet insertion hole, and the rotation A non-magnetic material disposed on the rotating shaft side of the core, and a spider extending from the rotating shaft is disposed in the lower part between the permanent magnets, and the centers of the permanent magnets on the non-magnetic material side are denoted by mc1 and mc2. When the distance between mc1 and mc2 is d1, the distance from mc1 to the center p of the spider on the nonmagnetic material side is d2, and the spider position coefficient Cp is used, the spider position coefficient is expressed as d2 = Cp · d1. A permanent magnet type rotating electrical machine characterized in that Cp is Cp≈0.5. 固定子鉄心のティースに巻線を施した固定子と、放射状に配置された永久磁石挿入孔と回転軸とを有する回転子鉄心と、前記永久磁石挿入孔に埋め込まれた永久磁石と、前記回転子鉄心の前記回転軸側に配置された非磁性体とを有し、前記回転軸から伸びるスパイダが前記永久磁石間下部に配置され、前記永久磁石の前記非磁性体側の中心をｍｃ１，ｍｃ２とし、このｍｃ１，ｍｃ２の距離をｄ１とし、ｍｃ１から前記スパイダの前記非磁性体側の中心ｐまでの距離をｄ２とし、スパイダ位置係数Ｃｐを用いてｄ２＝Ｃｐ・ｄ１と表したとき、スパイダ位置係数Ｃｐを０.４≦Ｃｐ≦０.６としたことを特徴とする永久磁石式回転電機。 A stator in which teeth of the stator core are wound, a rotor core having a radially arranged permanent magnet insertion hole and a rotation shaft, a permanent magnet embedded in the permanent magnet insertion hole, and the rotation A non-magnetic material disposed on the rotating shaft side of the core, and a spider extending from the rotating shaft is disposed in the lower part between the permanent magnets, and the centers of the permanent magnets on the non-magnetic material side are denoted by mc1 and mc2. When the distance between mc1 and mc2 is d1, the distance from mc1 to the center p of the spider on the nonmagnetic material side is d2, and the spider position coefficient Cp is used, the spider position coefficient is expressed as d2 = Cp · d1. A permanent magnet type rotating electrical machine characterized in that Cp is set to 0.4 ≦ Cp ≦ 0.6.
JP2002010951A 2002-01-21 2002-01-21 Permanent magnet rotating electric machine Expired - Fee Related JP3753073B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002010951A JP3753073B2 (en) 2002-01-21 2002-01-21 Permanent magnet rotating electric machine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002010951A JP3753073B2 (en) 2002-01-21 2002-01-21 Permanent magnet rotating electric machine

Publications (2)

Publication Number Publication Date
JP2003219586A JP2003219586A (en) 2003-07-31
JP3753073B2 true JP3753073B2 (en) 2006-03-08

Family

ID=27648546

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002010951A Expired - Fee Related JP3753073B2 (en) 2002-01-21 2002-01-21 Permanent magnet rotating electric machine

Country Status (1)

Country Link
JP (1) JP3753073B2 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4572647B2 (en) * 2004-10-01 2010-11-04 株式会社日立製作所 Permanent magnet rotating electrical machine and wind power generation system
US9163546B2 (en) * 2010-12-27 2015-10-20 Mitsubishi Heavy Industries, Ltd. Power generator power generation facility
US11901799B2 (en) * 2021-02-08 2024-02-13 General Electric Company Electrical machines for integration into a propulsion engine

Also Published As

Publication number Publication date
JP2003219586A (en) 2003-07-31

Similar Documents

Publication Publication Date Title
JP5935615B2 (en) Rotating electrical machine rotor
KR101355257B1 (en) Axial motor
JP5849890B2 (en) Double stator type motor
WO2011002043A1 (en) Permanent magnet type rotary electrical machine
JP5891089B2 (en) Permanent magnet synchronous machine
US20060022553A1 (en) Rotating electric machine
JP2002078259A (en) Permanent magnet rotor
JP6421926B2 (en) Permanent magnet synchronous machine
JP2008295138A (en) Rotary electric machine
JPH08275419A (en) Rotor of permanent magnet type rotary machine
CN103095014A (en) Rotor And Motor
JP2011045237A (en) Universal motor
JP2014060837A (en) Axial gap type rotary electric machine, electrically-driven wheel chair with the rotary electric machine, and electrically-driven bicycle
JP4457777B2 (en) Rotating electric machine
JP2006288043A (en) Permanent magnet type motor
JP3772819B2 (en) Coaxial motor rotor structure
JP3753073B2 (en) Permanent magnet rotating electric machine
JP3172504B2 (en) Rotor of permanent magnet type reluctance type rotating electric machine
JP2007228790A (en) Motor
JP2001275285A (en) Permanent magnet motor
JP3268762B2 (en) Rotor of rotating electric machine and method of manufacturing the same
JP3681459B2 (en) Synchronous motor
JPH03106850U (en)
JP5946258B2 (en) PM stepping motor
JP2005039909A (en) Permanent magnet embedded type motor

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20040218

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20050630

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20050712

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20050912

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20051122

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20051205

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20081222

Year of fee payment: 3

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20091222

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101222

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20101222

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111222

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20111222

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20121222

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20131222

Year of fee payment: 8

LAPS Cancellation because of no payment of annual fees