[go: up one dir, main page]

EP0080585B1 - Compresseur à pistons rotatifs - Google Patents

Compresseur à pistons rotatifs Download PDF

Info

Publication number
EP0080585B1
EP0080585B1 EP82109275A EP82109275A EP0080585B1 EP 0080585 B1 EP0080585 B1 EP 0080585B1 EP 82109275 A EP82109275 A EP 82109275A EP 82109275 A EP82109275 A EP 82109275A EP 0080585 B1 EP0080585 B1 EP 0080585B1
Authority
EP
European Patent Office
Prior art keywords
main rotor
rotor
screw
line
straight line
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
Application number
EP82109275A
Other languages
German (de)
English (en)
Other versions
EP0080585A1 (fr
Inventor
Beteiligungsgesellschaft Mbh Technika
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.)
TECHNIKA BETEILIGUNGSGESELLSCHAFT MBH
Original Assignee
TECHNIKA BETEILIGUNGSGESELLSCHAFT MBH
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 TECHNIKA BETEILIGUNGSGESELLSCHAFT MBH filed Critical TECHNIKA BETEILIGUNGSGESELLSCHAFT MBH
Priority to AT82109275T priority Critical patent/ATE14779T1/de
Publication of EP0080585A1 publication Critical patent/EP0080585A1/fr
Application granted granted Critical
Publication of EP0080585B1 publication Critical patent/EP0080585B1/fr
Expired legal-status Critical Current

Links

Images

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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T74/00—Machine element or mechanism
    • Y10T74/19—Gearing
    • Y10T74/19949—Teeth
    • Y10T74/19953—Worm and helical

Definitions

  • the invention relates to a parallel and outer-axis rotary compressor with at least one helically toothed main rotor and in each case a secondary rotor meshing therewith.
  • Such a rotary compressor is e.g. B. become known from DE-OS 2505 113.
  • the laid-open specification deals in particular with the formation of the tooth flanks of the secondary rotor, around the blow hole of the compressor toothing which is present in rotary piston compressors and which arises from the fact that the contact line, along which. the tooth flanks of one tooth of the main and secondary rotors of an engaged pair of teeth lie against each other, not up to the housing edge, which is the intersection of the two housing bores (see also Rinder, Springer-Verlag Vienna, New York 1979, p. 72 ff ) to keep it as small as possible.
  • U.S. Patent No. 2,622,787 is concerned with reducing leakage due to the blow hole.
  • the rotors of screw compressors - in order to keep the leakage as small as possible - must be manufactured with the greatest precision, which requires complex and expensive tools and machine tools. Due to the complicated design of the individual profiles are egg. gene milling cutters required, whereby the manufacture of a rotor usually requires several operations (pre-milling with so-called roughing cutters and then finishing with finishing or fine milling cutters). A cutter set for a pair of rotors costs between DM 20,000 and 50,000 depending on the diameter. In addition, there is the effort for the necessary final checks.
  • Rotary lobe compressors with different delivery volumes are commercially available in order to meet the respective desired requirements. Accordingly, the manufacturers offer compressor series in which the distance between the stages is chosen to be relatively large because of the expensive manufacture, so that too many expensive tools do not have to be manufactured and kept in stock. The result of this is that the individual types of rotary compressor are not operated directly in their optimal range or in the vicinity of the optimum range, but rather over a larger range.
  • 1 shows the specific power consumption in (kW / m 3 / min) over the delivery volume (m 3 / min).
  • the circumferential speed of a rotor or its speed could also be plotted on the abscissa; the qualitative statement would not change here.
  • the optimum operating point is - as can be seen from FIG.
  • the rotary lobe compressors currently on the market run in the BAC range, i.e. not exclusively in or close to the optimal range, which would be around B 'AC', in order to have the flow rate flow of one type connected as seamlessly as possible to the next larger type.
  • the expansion of the flow rate range for each type must be achieved by changing the speed by means of a transmission gear (belt or gear drives or by means of speed control of the drive motor). If you wanted to operate the rotary lobe compressors in area B 'AC', the delivery volume would have to be reduced. As a result, however - as indicated above - a larger number of rotary lobe compressor types and thus a larger number of expensive tools would again be required.
  • the object of the invention is to provide a rotary compressor of the type mentioned, which is simple to manufacture and which requires relatively inexpensive tools for producing the profiles.
  • the dimensional control should also be able to be carried out precisely, inexpensively and simply.
  • the tooth flanks of the main rotor are oblique open jet screw surfaces, which are formed by screwing each of a straight line crossing the screw axis generating straight line, the inclination angle of the generating straight line to a plane that is perpendicular to the screw axis in its Absolute value is smaller than the angle of inclination of the tangent of the fillet screw line to this plane and the rise of the generating straight line and the rise of the tangent to the fillet screw line have opposite signs.
  • a further embodiment of the invention can be such that the tooth flanks of the secondary rotor are generated and determined against one another by the relative path of a point lying on a head line (main rotor head point) when the main and secondary rotors roll.
  • the main rotor advantageously has at least three teeth.
  • the tooth flanks of the main and secondary rotors are not composed of curve segments, but are formed by a steady, uniform, analytically definable curve shape from head point to head point because of the generating straight lines.
  • the tooth flanks of the main rotor have the shape of oblique, open jet screw surfaces (see Wunderlich, descriptive geometry, Volume 2, of the BI Hochschulta series schbooks, volume 133, 1967, page 176 ff., and in particular page 183, point 97d).
  • the generatrix of the main rotor is therefore a straight line, the flanks in the frontal section being formed by the symmetrical part of an intricate circular involute.
  • the main rotor can be produced once by means of a hob cutter in a hobbing process. Since such a milling cutter does not touch the jet screw surface exactly along the generating straight line, but along a space curve, the profile shape of a suitable milling cutter is therefore not exactly a straight line, but a curved line (profile milling cutter).
  • the flank can be produced by planing, in particular by means of hobbing or butting. Such methods are common and common in transmission engineering; they are more precise than a hobbing process, but are more time-consuming.
  • the manufacture of the main rotor is significantly cheaper and the final inspection of the main rotor is also simplified, the simplification in particular being that the main rotor can be quasi two-dimensionally traversed by means of a simple measuring device. Due to the simplified measuring device or the simplified measuring method for the final inspection, the tolerance band for the main rotor can also be significantly reduced.
  • the tooth flanks of the secondary rotor are formed by a wheel curve, which can be produced with a profile cutter with an arc-like shape.
  • a rotary lobe compressor series can be offered with a gradation which is significantly refined compared to known compressor series. It is possible to optimize the efficiency of the individual rotary lobe compressors in the series by choosing the optimum circumferential speeds in the absence of gears (gears and pinions or belts, adapted to the standard electrical speed of the drive, which is designed as an electric motor, for example).
  • the single rotary compressor can be operated in direct drive in the area B 'AC' (Fig. 1), so that the optimal working area can be used.
  • the geometry of the manufactured rotor is also much easier to measure, which - as mentioned above - makes the final inspection less expensive.
  • the individual rotary compressor of such a series can be driven directly without the interposition of an intermediate gear, so that an improvement in efficiency can be achieved in this way alone.
  • a further advantage of the embodiment according to the invention also consists in the following: in known rotors the tooth depth, ie. H. the groove depth between two neighboring head lines is large. As a result, the ratio of core diameter to outer diameter is also large. In the case of known rotors, this value is between 0.4 and 0.5. In the rotor according to the invention, however, which is defined by the features of the characterizing part of claim 1, the ratio of core diameter to outer diameter is approximately 0.95.
  • the deflections to be expected in the main rotor according to the invention are thus practically zero in comparison to the known main rotors. As a result, the tolerances can be kept very small and the individual main rotor is also very robust. Due to these tolerances, the efficiency can be further improved.
  • the rotary lobe compressor which is generally designated 10, has a compression chamber 14 in a housing 12, in which a main rotor 16 and a secondary rotor 18 meshing therewith are arranged.
  • the main rotor 16 has at one end an extension 24 divided into two areas 20 and 22 with different diameters, of which one area 20 with a larger diameter of the bearing by means of roller bearings 26 and the other area 22 with a smaller diameter for connecting a drive, not shown serves.
  • the bearing 26 is located in a bearing recess 28 in a bearing disk 30 which is fixedly connected to the housing 12 together with an end cover 32 via a screw connection 34.
  • a sealing ring 36 is provided to seal the bearing 26 to the outside.
  • the main rotor 16 has a further journal 38 which in a roller bearing 40 and in a ball bearing 42 in a first bearing opening 44 of the housing 12.
  • the mounting of the bearings 40 and 42 takes place on the inside via a nut 46 screwed onto the bearing pin 38 and on the outside via a compression spring 48 which is supported on a second end cover 50, which is firmly connected to the housing by means of screw bolts 52, with the interposition of a fixing sleeve 53.
  • the secondary rotor 18 has a bearing journal 54 and 56 on the end face, of which the bearing journal 54 is supported in a roller bearing 58 in the bearing washer 30 and the bearing journal 56 in a roller bearing 60 and a ball bearing 62 in a second bearing opening 64 in the housing 12 .
  • the bearings 60 and 62 are held or axially fixed on the inside diameter or on the inner ring of the bearings by means of a nut 66 screwed onto the bearing journal 56 and on the outside of the bearing outer ring via a compression spring 68 with the interposition of a fixing sleeve 70.
  • the reference number 72 denotes the fillet line of the main rotor and the reference number 74 the dashed line of the secondary rotor.
  • the reference numbers 76 and 78 denote the top lines of the main and secondary rotors.
  • FIG. 3 shows a cross section along the line 111-111 of FIG. 1.
  • the main rotor 16 has a total of four teeth, the head points of which are represented by the reference numbers 80, 82, 84 and 86 in the section according to FIG. 3.
  • the teeth are formed using an inclined, open jet screw surface.
  • the generatrix of this jet screw surface, which forms a screw, the circumferential curve between the head points 80-82; 82-84; 84-86 and 86-80 is a circular involute, is a straight line G which runs obliquely to the screw axis S (see FIG. 8).
  • angle a which the straight line G forms with a plane EE that runs perpendicular to the screw axis, is absolute, i.e. in terms of its numerical value, smaller than the angle of inclination ⁇ of the fillet screw line of the profile in question, the rise of the straight line G having an opposite sign with respect to that of the rise of the throat screw line (see FIG. 8).
  • the secondary rotor 18 has nine teeth (which are not numbered in detail), wherein, as can be seen from FIGS. 4 to 7, the tooth flanks between the teeth are determined by the relative path of the head points 80 to 84 of the main rotor 16.
  • the secondary rotor tooth flanks in the case of pointed secondary rotor teeth are not circles, but intertwined epitrochoids, which, however, can be approximately replaced by their circles of curvature during manufacture, that is, by arcs.
  • FIG. 4 shows a first position of the main rotor and the secondary rotor relative to one another, in which the head point 82 of the main rotor 16 in the position shown, ie. H. the center point of the head point lies exactly on the connecting line V-V of the central axes of the rotors.
  • the head point 82 is also aligned with the throat point 82 'of the secondary rotor 18, which is also on the connecting line between the center points of the two rotors.
  • the center line of the head and the center of the throat coincide.
  • the head points 88 and 90 of the secondary rotor 18 lie exactly on the tooth flank of the tooth which has the head point 82.
  • the head point center line with the head point 82 moves clockwise, the head point 82 running exactly on the tooth flank of the secondary rotor in such a way that the tooth flank of the secondary rotor passes through the Path of the head point 82 is determined.
  • the head point 90 of the secondary rotor 18 is still on the other tooth flank.
  • the throat center line of the secondary rotor 18 has migrated counterclockwise by a smaller amount in accordance with the speed ratio between the main rotor and the secondary rotor from the connecting line of the center points of the two rotors.
  • the head point 82 of the main rotor is located in the region of the head point 88 of the secondary rotor, the head point 90 still lying on the tooth flank of the main rotor.
  • FIG. 7 it can be seen that the head point 82 has come free from the secondary rotor, but the head point 90 still remains on the tooth flank.
  • the head point 84 comes into engagement with the secondary rotor, and the sequence or the geometry is the same as in FIGS. 4 to 7: the tooth flanks of the secondary rotor are formed by the respective head point of the main rotor, when if a head point of the main rotor is located between two head points of the secondary rotor, the two mentioned head points rest on the tooth flank or the tooth flanks of the main rotor.
  • FIG. 8 The screw axis S-S, to which a plane E-E runs perpendicular, is shown schematically.
  • P is the radius of the screw cylinder of the fillet screw line 72, the projection of which intersects the screw axis at point P.
  • the generating line is labeled G-G.
  • the generating straight line G-G forms an angle a with the plane E-E, whereas the tangent 73 to the fillet screw line 72 at point P includes an angle ⁇ with the plane E-E.
  • the angle a is absolute, i.e. H. in terms of its value, smaller than the angle ⁇ ; however, the inclinations of both angles have opposite signs.
  • the flank end intersection curve of the beam screwing surface generated by the straight line GG lies between two points P, and P 2 and has the designation F (see FIG. 8, below), which can be derived from the generation as an involute. Due to the complexity of the calculation method, the tip circle radius u K and the angle 'PK , to which each tip point is assigned in each cross-section, must be determined numerically by iteration, an explicit, closed representation being practically impossible.
  • tooth flanks of the secondary rotor are formed by the head point of the main rotor in the case of pointed secondary rotor teeth, an explicit calculation of the tooth flanks of the secondary rotor, which is to be regarded as a convoluted impeller line, is possible by calculation with electronic data processing.
  • the blow hole can be made practically zero. This is a further, particular advantage of the configuration according to the invention and for this reason the profile shape is also particularly advantageously suitable for small delivery volumes where even the smallest of leaks can lead to a significant reduction in efficiency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)
  • Rotary-Type Compressors (AREA)

Claims (3)

1. Compresseur à pistons rotatifs parallèles et excentrés, comprenant au moins un rotor principal mené à denture oblique et un rotor auxiliaire engrenant dans ce dernier, caractérisé par le fait que les flancs des dents du rotor principal sont des surfaces hélicoïdales rayonnantes, inclinées et ouvertes qui sont formées par le vrillage d'une droite génératrice respective (G-G) coupant à l'oblique l'axe (S-S) de l'hélice, l'angle d'inclinaison (a) de cette droite génératrice, par rapport à un plan s'étendant perpendiculairement à l'axe de l'hélice, ayant une valeur absolue plus petite que l'angle d'inclinaison (β) de la tangente de la ligne hélicoïdale des creux (72) par rapport à ce plan, la pente ascendante de la droite génératrice et la pente ascendante de la tangente à la ligne hélicoïdale des creux étant de signes opposés.
2. Compresseur à pistons rotatifs selon la revendication 1, caractérisé par le fait que les flancs des dents du rotor auxiliaire sont engendrés et déterminés par la trajectoire relative d'un point (82) situé sur une ligne (76) des crêtes (point de crête du rotor principal) lors de la dérive mutuelle des rotors principal et auxiliaire (16, 18).
3. Compresseur à pistons rotatifs selon la revendication 1 ou 2, caractérisé par le fait que le rotor principal (16) comporte au moins trois dents.
EP82109275A 1981-10-09 1982-10-07 Compresseur à pistons rotatifs Expired EP0080585B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82109275T ATE14779T1 (de) 1981-10-09 1982-10-07 Drehkolbenverdichter.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3140107 1981-10-09
DE19813140107 DE3140107A1 (de) 1981-10-09 1981-10-09 Drehkolbenverdichter

Publications (2)

Publication Number Publication Date
EP0080585A1 EP0080585A1 (fr) 1983-06-08
EP0080585B1 true EP0080585B1 (fr) 1985-08-07

Family

ID=6143717

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82109275A Expired EP0080585B1 (fr) 1981-10-09 1982-10-07 Compresseur à pistons rotatifs

Country Status (5)

Country Link
US (1) US4662832A (fr)
EP (1) EP0080585B1 (fr)
JP (1) JPS58135395A (fr)
AT (1) ATE14779T1 (fr)
DE (1) DE3140107A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8434596U1 (de) * 1983-12-14 1985-02-21 Boge Kompressoren Otto Boge Gmbh & Co Kg, 4800 Bielefeld Drehkolbenverdichter
FR2609310B1 (fr) * 1987-01-06 1991-04-12 Baudot Hardoll Sa Profils de rotors, du type a vis, pour machines tournantes vehiculant un fluide gazeux
JP7229720B2 (ja) * 2018-10-26 2023-02-28 株式会社日立産機システム スクリュー圧縮機

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB254986A (en) * 1925-10-06 1926-07-15 Alexander Johan Mollinger Improvements in or relating to screw pumps
AT169479B (de) * 1946-07-18 1951-11-26 Ljungstroems Angturbin Ab Drehkolbenmaschine
CH384768A (de) * 1959-09-02 1965-02-26 Ingersoll Rand Co Strömungsmittelpumpe oder -motor
GB1197432A (en) * 1966-07-29 1970-07-01 Svenska Rotor Maskiner Ab Improvements in and relating to Rotary Positive Displacement Machines of the Intermeshing Screw Type and Rotors therefor
DE2360403A1 (de) * 1973-12-04 1975-06-05 H & H Licensing Corp Schraubenkompressoranlage zum verdichten von gasfoermigen medien, insbesondere fuer geringe ansaugvolumina

Also Published As

Publication number Publication date
US4662832A (en) 1987-05-05
EP0080585A1 (fr) 1983-06-08
DE3140107A1 (de) 1983-04-28
ATE14779T1 (de) 1985-08-15
JPS58135395A (ja) 1983-08-11

Similar Documents

Publication Publication Date Title
DE69503385T2 (de) Kronenradgetriebe, kronenrad und verfahren und werkzeug zur herstellung des kronenrades
EP1995010B1 (fr) Procédé de laminage diagonal destiné à la production de flancs dotés d'un décalage prédéfini pour convexité prédéfinie
EP2358494B1 (fr) Procédé de traitement des flancs de dentelures essentiellement cylindriques, mais modifiées et bombées en largeur dans le procédé de roulement en diagonale
EP2412467B1 (fr) Procédé de fraisage d'une dent de roue conique selon le procédé de fraisage continu
AT400974B (de) Schraubenrotormaschine
DE2508435C3 (de) Parallel- und außenachsige Rotationskolbenmaschine mit Kammeingriff
DE2512651A1 (de) Geraeuscharmes zahnradgetriebe
DE3034299C2 (fr)
DE2911415C2 (de) Parallel- und außenachsige Rotationskolbenmaschine mit Kämmeingriff
EP3653325B1 (fr) Procédé de production par enlèvement de matière d'une roue dentée présentant une denture à double inclinaison
DE594691C (de) Schraubenverdichter, bestehend aus rechts- und linksgaengigen, miteinander in Eingriff stehenden, durch Zahnraeder gekuppelten Schrauben
DE2108714A1 (de) Drehkolbenmaschine
EP0077031B1 (fr) Compresseur à pistons rotatifs
EP0080585B1 (fr) Compresseur à pistons rotatifs
DE3934604A1 (de) Verfahren zum herstellen von profilierten werkstuecken
DE2234777A1 (de) Schraubenmaschine
DE102019212221A1 (de) Wellgetriebe
DE102016122701B4 (de) Gewindeformer und Verfahren zur Herstellung eines Gewindeformers
EP0149446A2 (fr) Compresseur à piston rotatif
DE3345262A1 (de) Rotoren fuer schraubenrotormaschine und herstellungsverfahren
DE3226355C2 (de) Gewindebohrer
DE102019212220A1 (de) Wellgetriebe
CH109955A (de) Zahnräder-Rotationsmaschine.
DE19942272C1 (de) Fräswerkzeug
DE3301140A1 (de) Volumetrische schnecken- und zahnrad-maschine

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE CH FR GB IT LI NL SE

17P Request for examination filed

Effective date: 19831205

ITF It: translation for a ep patent filed
GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Designated state(s): AT BE CH FR GB IT LI NL SE

REF Corresponds to:

Ref document number: 14779

Country of ref document: AT

Date of ref document: 19850815

Kind code of ref document: T

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: AT

Payment date: 19861030

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19861031

Year of fee payment: 5

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19871007

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19871008

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LI

Effective date: 19871031

Ref country code: CH

Effective date: 19871031

Ref country code: BE

Effective date: 19871031

BERE Be: lapsed

Owner name: TECHNIKA BETEILIGUNGSG-M.B.H.

Effective date: 19871031

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19880501

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
GBPC Gb: european patent ceased through non-payment of renewal fee
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19880630

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19881122

EUG Se: european patent has lapsed

Ref document number: 82109275.6

Effective date: 19880712