US3807911A - Multiple lead screw compressor - Google Patents

Multiple lead screw compressor Download PDF

Info

Publication number
US3807911A
US3807911A US35966573A US3807911A US 3807911 A US3807911 A US 3807911A US 35966573 A US35966573 A US 35966573A US 3807911 A US3807911 A US 3807911A
Authority
US
United States
Prior art keywords
portions
rotors
lands
grooves
inlet
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 - Lifetime
Application number
Inventor
T Caffrey
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.)
Fuller Co
INDIANA NATIONAL BANK
Original Assignee
Davey Compressor Co
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
Priority to US16802371A priority Critical
Priority to US35966573 priority patent/US3807911A/en
Application filed by Davey Compressor Co filed Critical Davey Compressor Co
Application granted granted Critical
Publication of US3807911A publication Critical patent/US3807911A/en
Assigned to WELLS FARGO BUSINESS CREDIT, A CORP. OF CA. reassignment WELLS FARGO BUSINESS CREDIT, A CORP. OF CA. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AERO-DRI CORPORATION, A CORP. OF OH., DAVEY COMPRESSOR COMPANY, A CORP. OF OH.
Assigned to AERO-DRI CORPORATION, A CORP. OF OH., DAVEY COMPRESSOR COMPANY, AN OHIO CORP. reassignment AERO-DRI CORPORATION, A CORP. OF OH. LICENSE (SEE DOCUMENT FOR DETAILS). Assignors: WELLS FARGO BUSINESS CREDIT
Assigned to INDIANA NATIONAL BANK, THE reassignment INDIANA NATIONAL BANK, THE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AERO-DRI CORPORATION, DAVEY COMPRESSOR COMPANY
Assigned to AERO-DRI CORPORATION, A CORP. reassignment AERO-DRI CORPORATION, A CORP. RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: WELLS FARGO BUSINESS CREDIT, A CA. CORP.
Assigned to FIRST NATIONAL BANK OF CINCINNATI, THE, 425 WALNUT STREET, CINCINNATI, OHIO 45202 reassignment FIRST NATIONAL BANK OF CINCINNATI, THE, 425 WALNUT STREET, CINCINNATI, OHIO 45202 LICENSE (SEE DOCUMENT FOR DETAILS). Assignors: DAVEY COMPRESSOR COMPANY
Assigned to DAVEY COMPRESSOR COMPANY, AERO-DRI CORPORATION reassignment DAVEY COMPRESSOR COMPANY RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: INDIANA NATIONAL BANK
Assigned to DAVEY COMPRESSOR COMPANY reassignment DAVEY COMPRESSOR COMPANY RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: STAR BANK, NATIONAL ASSOCIATION, CINCINNATI
Assigned to FULLER COMPANY reassignment FULLER COMPANY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: DAVEY COMPRESSOR COMPANY
Anticipated expiration legal-status Critical
Assigned to BANK OF AMERICA, NATIONAL ASSOCIATION, AS AGENT reassignment BANK OF AMERICA, NATIONAL ASSOCIATION, AS AGENT SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KECO INDUSTRIES, INC.
Assigned to BANK OF AMERICA, N.A. reassignment BANK OF AMERICA, N.A. RELEASE Assignors: KECO INDUSTRIES, INC.
Assigned to KECO INDUSTRIES, INC. reassignment KECO INDUSTRIES, INC. TERMINATION OF SECURITY INTEREST Assignors: BANK OF AMERICA, N.A., AS AGENT
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04CROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C18/00Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/08Rotary-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
    • F04C18/082Details specially related to intermeshing engagement type pumps
    • F04C18/084Toothed wheels

Abstract

A rotor structure is disclosed for a fluid compressor of the character having a pair of complementary, intermeshing rotatable rotors for transferring and compressing a fluid from an inlet into the compressor to an outlet from the compressor. The rotor includes helical land and intervening helical groove means for intermeshing with complementary helical land and groove means of a complementary rotor. The helical land and groove means includes a first portion having a first constant helix angle and a second portion having a second constant helix angle which is different from the first helix angle. The two helical portions are disposed on shaft means and meet in a transition area intermediate the opposite ends of the shaft means and in which area the lands and grooves are disposed in mating relationship. One of the helical portions is integral with the shaft means, and the other helical portion is defined by a separate component adapted to be mounted on the shaft means and suitably interconnected with the one helical portion.

Description

United States Patent 1191 Caffrey MULTIPLE LEAD SCREW COMPRESSOR [75] Inventor: Terence Caffrey, Kent, Ohio [73] Assignee: Davey Compressor Company, Kent,

Ohio 1 [22] Filed: May 14, 1973 [21] App]. No.: 359,665

4 Related U.S. Application Data [63] Continuation of Ser, No. 168,023, Aug. 2, 1971,

abandoned.

52 u.s.c 1. ..4l8/9,4l8/20l 51 Int. Cl. F01C1/16,F04C 1/10,F04c 17/12 58 FieldofSearch 418/9, 197, 201,202, 203

[56] References Cited UNITED STATES PATENTS 3 ,424',373 1/1969 Gardner 418/201 2,652,192 9/1953 Chilton 418/197 2,369,539 2/1945 0613mm 418/203 1,597,411 8/1926 Kinney 418/202 2,586,842 2/1952 McCallum 418/201 2,691,482 10/1954 Ungar 418/9 2,975,963 3/1961 Nilsson 418/9 2,804,260 8/1957 Nilsson et al. 418/9 FOREIGN PATENTS OR APPLICATIONS 210,088

l/l924 Great Britain 418/202 [11] 3,807,911 1451 Apr. 30, 1974 Primary ExaminerCarlton R. Croyle Assistant Examiner-John J. Vrablik Attorney, Agent, or Firm-Meyer, Tilberry & Bod

[ ABSTRACT A rotor structure is disclosed for a fluid compressor of the character having a pair of complementary, intermeshing rotatable rotors for transferring and compressing a fluid from an inlet into the compressor to an outlet from the compressor. The rotor includes helical land and intervening helical groove means for intermeshing with complementary helical land and groove means of a complementary rotor. The helical land and groove means includes a first portion having a first constant helix angle and a second portion having a second constant helix angle which is different from the first helix angle. The two helical portions are disposed on shaft means and meet in a transition area intermediate the opposite ends of the shaft means and in which area the lands and grooves are disposed in mating relationship. One of the helical portions is integral with the shaft means, and the other helical portion is defined by a separate component adapted to be mounted on the shaft means and suitably interconnected with the one helical portion.

5 Claims, 6 Drawing Figures SHEEI 1 BF 2 [\l INVENTOR. LK TERENCE CAFFREY W% 7% ya ATTOR NEYS.

PATENIED H I 3.807311 SHEET 2 [1F 2 INVENTOR.

T E RE NCE CAF FREY 77% Hay ATTORNEYS.

MULTIPLE LEAD SCREW COMPRESSOR This is a continuation, of application Ser. No. 168,023 filed Aug. 2, 1971.

This invention relates to the art of helical screw-type compressors and, more particularly, to helical screw or rotor components for such compressors.

Rotary screw-type compressors have been provided heretofore and generally include a pair of intermeshing, complementary rotors positioned within a compressor housing, and means for rotating the intermeshed rotors relative to one another. The compressor housing includes an inlet opening into which fluid such as air, flows and an outlet opening through which compressed fluid flows as a result of rotation of the intermeshing rotors which operate to transfer and compress the fluid from the inletto the outlet of the compressor. Compressors of this type are employed for compressing gases which, during transfer and compression, move axially along the rotors. Such rotary screw compressors may beoperated dry or wet. In wet operated compressors, liquid is introduced into the compression chamber to effect a seal between the rotors. Dry compressors, on the other hand, rely upon extremely close tolerances between intermeshing lands and grooves of the rotors to effect a seal therebetween. The introduction of liquids into the compression chamber of a screw compressor, of course, provides for additional sealing between the rotor components and serves further to dissipate the heat of compression. The compression ratio which can be realistically achieved under dry operation is about 3:l or 4:1 whereas a wet operated compressor may have a compression ratio of up to 8:1 or 9:1.

Prior art screw compressors of the above character have generally been constructed with constant lead helical lands and intervening grooves on the complementary intermeshing rotors. Such construction limits the efficiency and performance of the compressors, especially at higher compression ratios. In this respect, the discharge velocity from a screw compressor having compressor. Efforts have been made in the past to provide rotary screw-type compressors with rotors having lands and grooves which continuously vary'in lead from one end of the rotor to the other. While such rotor components may provide for increasing the discharge areaof a compressor to relieve backflow and the resultant overworking of the compressor, it remains that a continuously variable lead rotor-is both extremely difficult and expensive to manufacture.

Backflow advantageously is relieved in accordance with the present invention by employing rotors or screws having helical lands and intervening grooves which have a different helix angle or lead at the intake end of the rotor from the lead thereof at the discharge end. By this arrangement, it is possible to provide a discharge port for a screw compressor which is approximately 2.25 times the size of the discharge port of a compressor of comparable size employing rotorshaving a constant lead. Moreover, such a rotor is structurally simple and reasonably inexpensive to produce relative to a continuously varying lead rotor..

Accordingly, it is an outstanding object of the present invention to provide a rotor component for screw-type.

fluid compressors which provides for increasing the efficiency of a constant lead screw compressor of a given size by permitting enlargement of the discharge port thereof to achieve a reduction in discharge velocity without backflow and resultant additional work byv the compressor.

A further object of the present invention is the provision of a rotor component of the above character which includes helical lands and intervening grooves in portions having different leads and in each of which portions the lead is constant along the length thereof.

Yet another object of the present invention is the provision of a rotor component of the above character which is reasonably simple and inexpensive to manufacture. I

Still another object of the present invention is the provision of a screw compressor rotor of the above character wherein the two helical portions are defined by separate components, each having helical lands and intervening grooves and wherein the lead of each portion is constant along'its length, thus facilitating the manufacture thereof.

Still another object of the present invention is the provision of a rotor of the above character wherein the separate portions are adapted to be readily interconnected to define a rotor component having helical lands and intervening grooves in portions having different leads, and which portions are interconnected in a manner whereby they meet in a transition area in which the lands and grooves of the two portions are disposed in mating relationship.

The foregoing objects will in part beobviousand in part more fully pointed out hereinafter in conjunction with the following description of the drawing of a preferred embodiment and in which:

FIG. 1 is a plan view, partially in section, illustrating a rotary screw-type compressor having a pair of rotor components made in accordance with the present invention; I

FIG. 2 is a sectional elevation of the compressor of FIG. 1, the section being taken along line 2--2 in FIG.

1, I FIG. 3 is a plan view of a male rotor made in accordance with the present invention;

FIG. 4 is a plan view of a female rotor made in accordance with the present invention;

FIG. 5 is a view in cross-section of the rotor illustrated in FIG. 3, the section being taken along line 55 in FIG. 3; and

' FIG. 6 is a schematic projection of complementary male and female rotors made in accordance with the present invention.

Referring now to the wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for limiting the same, a rotary screw-type compressor assembly 10 is illustrated in FIGS. I and 2 which is comprised of a housing 12 having an inlet port 14 at one end thereof and an outlet port 16 at the other end "thereof. Housing 12 includes cylindrical chambers 18 drawings in greater detail,

in a manner to support the rotors for rotation within the housing in intermeshing relationship. ()ne of the shaft portions such as shaft portion 28, for example, projects outwardly of housing 12 for suitable interconnection thereof with suitable drive means which is not illustrated. The intermeshing relationship between rotors 22 and 24 provides for rotor 24 to be rotated in response to rotation of rotor 22 through shaft portion 28. It will be understood, however, that shaft portion 32 could be extended exteriorly of housing 12 and that shaft portions 28 and 32 could be suitably interconnected such as by gear means to achieve rotation of rotor 24.

' Male rotor 22, as best illustrated in FIGS. 2 and 3, includes helical land means 34 and intervening helical groove means 36. The helical land means of the male rotor are in the form of lobes having convex outer side surfaces 40. In accordance with the present invention, the helical land means and intervening groove means of the male rotor is defined by two portions designated A Portion A extends from the inlet end of the compressor toward transition area E, and portion B extends from transition area E toward the outlet end of the compressor. The helical land and groove means of portions A and B each have a constant lead throughout the length thereof and, as is best illustrated in FIG. 3, the lead of portion A is greater than the lead of portion B. Preferably, the lead ratio of portion A' to portion B is approximately 3:1. It will be appreciated, however, that the lead ratio can be of any value greater or lesser than 3:1 and is limited only by manufacturing or strength considerations. The inner ends of portions A and B are interrelated in transition area E in a manner whereby the helical land and groove means of portions A and B are disposed in mating relationship. Thus, continuous but angularly related helical land and groove means are provided'which extend along the length of the rotor component.

In conjuction with the lead ratio of the helical land and groove means of portions A and B, it is desirable to maintain the total wrap angle thereof at less than 360. More particularly, it is preferred that the total wrap angle be approximately 270. The total wrap anconcave outer side surfaces 46. Similarly, helical groove means 44 are complementary to helical land means 34 of male rotor 22. Thus, rotors 22 and 24 are adapted to be disposed in side by side intermeshing reand B which meet in transition area designated by line gle, of course, is the angle circumscribed by the helical land and intervening groove means of both portions between the longitudinally oppositeends thereof. Similarly, portion A has a wrap angle which is defined by the angle circumscribed by the helical land and groove means thereof in extending from the ends thereof adjacent shaft portion 28 to transition area E, and portion B has a wrap angle which is defined by the angle circumscribed by the helical land and groove means thereof in extending from transition area E to the ends thereof adjacent shaft portion 26. In the preferred embodiment herein illustrated, portions A and B have a lead ratio of 3:1, as mentioned above, and the wrap angle of the helical land and groove means of each portion is approximately 135.

The structure of female rotor 24 is, of course, complementary to that of male rotor 22. In this respect, with reference to FIGS. 2 and 4 of the drawing, the female rotor includes helical land means 42-and intervening helical groove means 44. Helical land means 42 are complementary to helicalgroove means 36 of the male rotor and, accordingly, helical land means 42 include lationship.

The helical land and groove means of female rotor 24 include portions C and D corresponding respectively to portions A and B of male rotor 22. Portions C and D of the helical land and groove means are interrelated in a transition area therebetween denoted by line F. The transition areas of rotors 22 and 24, of course, coincide in location relative to the opposite ends of the rotors. Since the helical land and groove means of the male and female rotors are complementary, it will be appreciated, that the helical land and groove means of portion C have a lead corresponding to that of portion A of male rotor 22, and that the helical land and groove means of portion D have a lead corresponding to the lead of portion B of male rotor 22. Further, it will be appreciated that the lead ratio of portion C to portion D, the wrap angles of each portion and the total wrap angle will correspond with that of the male rotor, or vice versa.

The rotor members may be formed or produced in any suitable manner and preferably, are constructed in the manner illustrated in FIG. 5. In this respect, a male rotor 50 is illustrated which includes shaft means 52 carrying helical land and intervening helical groove means 54 defined by helical land and groove means portions 56 and 58. Portion 56 is integral with shaft means 52, and portion 58 is defined by a separate component suitably interconnected with portion 56. In the particular embodiment illustrated, portion 58 is an annular component having helical land and groove means in the outer surface thereof and having a cylindrical aperture 60 therethrough which is adapted to receive a cylindrical portion 62 of shaft means 52 which projects from the corresponding end of land and groove portion 56. Portion 58 is interconnected with portion 56 by bolt means 64, or the like, which extends through aperture 65 in portion.58 and has a threaded inner end disposed in a cooperatively threaded recess 66 in portion 56. Further, means is provided to assure that portion 58 is oriented relative to portion 56 so that the helical land and groove means of the two portions are disposed in mating relationship in the transition area therebetween defined by a line of juncture G. In this respect, portions 56 and 58 may be provided with a recess 68 and aperture 70, respectively, adapted to be aligned to receive a suitable dowel pin 72. It will be appreciated, of course, that recess 68 and aperture 70 are provided in the corresponding portions 56 and 58 so as to assure properalignment of the lands and grooves of the two portions uponinsertion of dowel 72 thereinto; After proper positioning is thus assured, aperture 65 and recess 66 can be provided in the corresponding portions 58 and 56, and bolt means 64 inserted thereinto to complete the assembly. I

A rotor constructed as'illustrated in FIG. 5 is very economical to produce in'that the shaft means and portion 56 of the helical land and groove means of the rotor can be turned or otherwise produced as an integral unit, while portion 58 having helical land and groove means of a different lead which is constant along its entire length can readily be turned or otherwise produced as a separate element or component. Thereafter, itis only necessary to position portion 58 on the shaft means and against portion 56, orient the two portions for the land and groove means thereof to mate, fix the positions thereof by means of -the dowel pin and interconnect the two portions by bolt means 64.

While the foregoing rotor structure has been described in conjunction with a male rotor, it will be appreciated that the female rotor is produced in the same manner. Further, it will be appreciated that means other than a dowel pin can be employed to assure proper alignment of the helical lands and grooves of the two portions of the rotor. In this respect, for example, the-projecting portion of the shaft and the opening in the separate component through which the shaft portion projects could be provided with aligned keyway means adapted to receive a key element which would properly orient the two rotor portions. Further, the projecting portion of the shaft could be provided with a flat and the opening through the separate component could be provided with a flat side interrupting the cylindrical contour thereof and which flat side would cooperate with the flat on the shaft to properly align the rotor'portions. Still further, although the helical land and groove means of portion 56 of the rotor is illustrated as being integral with shaft means 52, portion 56 could also be a separate component from the shaft means suitably interconnected therewith. It is also contemplated that portions 56 and 58 could be separate portions each integral with a corresponding shaft portion. In this instance, the two rotor portions would be suitably interconnected with the helical land and groove means thereof in mating relationship and the shaft portions thereof would together define shaft means for the rotor unit.

In use, complementary male and female rotor elements are disposed in a compressor housing in intermeshing relationship with one another and with high lead portions A and C thereof toward the'compressor inlet and low lead portions B and D thereof toward the compressor outlet. In a manner well known, fluid such as air enters the compressor inlet and is transferred therefrom to the compressor outlet by being captured in pockets or cells defined by the helical land and groove means of the rotating male and female rotors together with the chambers in which the rotors are di'sposed. During such transfer, the pockets in which the fluid is trapped gradually decrease in volume whereby the fluid is gradually compressed and is ultimately exhausted through the compressor-outlet under high pressure and velocity.

The working relationship of male and female rotors made in accordance with the present invention is scheare numbered 1 through 4. Similarly, female rotor 24 has helical land and groove me'ans portions C, and D having different leads corresponding, respectively, to the leads of portions A and B of the male rotor. Further, the helical lands and grooves of portions C and D are disposed in mating relationship. The grooves of female rotor 24 are numbered 1 through 6. The space be tween lines 73 and 74 of male rotor 22 together with. the space between lines 75 and 76 of female rotor 24 define the width of the compressor inlet-If the leads of the helical land and groove means of the rotors were constant throughout the lengths thereof the compressor outlet would have a width designated by lines .78. However, by-providing the portions of the rotors adjacent the outlet of the compressor with helical land and groove means having a lead which is less than that of the portions adjacent the inlet end of the compressor, a compressor outlet of greater width or size as designated by lines 80, advantageously is provided for. The small outlet opening necessitated by the use of constant lead rotors produces an undesirably. high output velocity from the compressor, and if the outlet is enlarged to decrease the velocity there is a resultant backflow V which disadvantageously results in imposing additional work on the compressor and thus decreasing its efficiency. The low lead feature provided for the outlet ends of the male and female rotors in accordancewith the present invention allows for the size of the discharge opening to be increased to reduce the output velocity of the compressor without the resultant backflow and loss of efficiency.

' While considerable emphasis has been placed herein on the structure of the rotors being such that the male rotor has four helical lands and intervening grooves and the female rotor has six helical lands and intervening grooves, it will be appreciated that other well known rotor configurations and ratios may be employed.

As many possible embodiments of the present invention may be made and as many possible changes may be made in the embodiment herein set forth, it is to be distinctly understood that the foregoing description of the preferred embodiment is to be interpreted merely as illustrative'of the present invention and not as a limitation.

I claim: I

1. In a rotary fluid compressor of the character comprising a housing having laterally communicating cylindrical chambers in which a pair of intermeshing male and female rotors are disposed for progressively compressing fluid between an inlet port at one end of said chambers and an outlet port at the other end of said chambers, said rotors having corresponding inlet and outlet ends with respect to said inlet and outlet ports, said male rotor having arcuately convex helical lands and said female rotor having complementaryv arcuately concave helical grooves, said lands andg'rooves being cooperable in response to rotation of said male and female rotors to progressively and continuously compress fluid between said inlet and outlet ports within a total wrap angle of the lands and grooves less than 360 and wherein the discharge port opens into said chambers peripherally of and laterally therebetween at the discharge ends of the rotors and the lead of said lands and grooves adjacent said outlet port is less than the lead of said lands and grooves adjacent said inlet port, the improvement comprising: said male and female rotors each including structurally separate first and second portions having helical lands and grooves, said first portions extending along said rotors from said inlet ends of the rotors to a transition plane intermediate said inlet and outlet ends and transverse to the axes of said rotors, said second portions extending along said rotors from said transition plane to said outlet ends, the lands and lgrooves'in said first portions having a constant ,lead, and the lands and grooves in said second portions having a constant lead which is less than the constant lead of said first portions, and means interconnecting said first and second portions of said rotors for the lands and grooves thereof to engage in mating relationship at said transition plane, said rotors including shaft means, one of said first and second portions being integral with said shaft means and the other of said first and second portions being apertured to receive said shaft means, the ends of said first and second portions at said transition plane having pairs of axially aligned recesses therein, at least one of the recesses of the pair in said other portion extending completely through said other portion, and the recess in said one portion aligned therewith being internally threaded, said interconnecting means including a pin in the other of the aligned recesses in said one and other portions and a threaded fastener extending through said one recess into threaded engagement with said threaded recess.

2. The improvement according to claim 1, wherein the ratio of the leads of said first portions to the leads of said second portions is approximately 3 to l.

3. The improvement according to claim 1, wherein the wrap angle of each of said first and said second por tions is approximately 135. 7

4. In a rotary fluid compressor of the character comprising a housing having laterally communicating cylindrical chambers in which a pair of intermeshing male and female rotors are disposed for progressively compressing fluid between an inlet port at one end of said chambers and an outlet port at the other end of said chambers, said rotors having corresponding inlet and outlet ends with respect to said inlet and outlet ports, said male rotor having arcuately convex helical lands and said female rotor having complementary arcuately concave helical grooves, said lands and grooves being cooperable in response to rotation of said male and female rotors to progressively and continuously compress fluid between said inlet and outlet ports within a total wrap angle of the lands and grooves less than 360, and wherein the discharge port opens into said chambers peripherally of and laterally therebetween at the discharge ends of the rotors and the lead of said lands and grooves adjacent said outlet port is less than the lead of said lands and grooves adjacent said inlet port, the improvement comprising: said male and female rotors each including structurally separate first and second portions having helical lands and grooves, said first portions extending along said rotors from said inlet ends of the rotors to a transition plane intermediate said inlet and outlet ends and transverse to the axes of said rotors, said second portions extending along said rotors from said transition plane to said outlet ends, the lands and grooves in said first portions having a constant lead, and the lands and grooves in said second portions having a constant lead which is less than the constant lead of said first portions, and means interconnecting said first and second portions of said rotors for the lands and grooves thereof to engage in mating relationship at said transition plane, said rotors including shaft means, said first portions being integral with said shaft means and said second portions being apertured to receive said shaft means, the ends of said first and second portions at said transition plane having pairs of axially aligned recesses therein, at least one of the recesses of the pair in said second portion extending completely through said second portion, and the recess in said first portion aligned therewith being internally threaded, said interconnecting means including a pin in the other of the aligned recesses in said first and second portions and a threaded fastener extending through said one reangle of each said portions is approximately

Claims (5)

1. In a rotary fluid compressor of the character comprising a housing having laterally communicating cylindrical chambers in which a pair of intermeshing male and female rotors are disposed for progressively compressing fluid between an inlet port at one end of said chambers and an outlet port at the other end of said chambers, said rotors having corresponding inlet and outlet ends with respect to said inlet and outlet ports, said male rotor having arcuately convex helical lands and said female rotor having complementary arcuately concave helical grooves, said lands and grooves being cooperable in response to rotation of said male and female rotors to progressively and continuously compress fluid between said inlet and outlet ports within a total wrap angle of the lands and grooves less than 360*, and wherein the discharge port opens into said chambers peripherally of and laterally therebetween at the discharge ends of the rotors and the lead of said lands and grooves adjacent said outlet port is less than the lead of said lands and grooves adjacent said inlet port, the improvement comprising: said male and female rotors each including structurally separate first and second portions having helical lands and grooves, said first portions extending along said rotors from said inlet ends of the rotors to a transition plane intermediate said inlet and outlet ends and transverse to the axes of said rotors, said second portions extending along said rotors from said transition plane to said outlet ends, the lands and grooves in said first portions having a constant lead, and the lands and grooves in said second portions having a constant lead which is less than the constant lead of said first portions, and means interconnecting said first and second portions of said rotors for the lands and grooves thereof to engage in mating relationship at said transition plane, said rotors including shaft means, one of said first and second portions being integral with said shaft means and the other of said first and second portions being apertured to receive said shaft means, the ends of said first and second portions at said transition plane having pairs of axially aligned recesses therein, at least one of the recesses of the pair in said other portion extending completely through said other portion, and the recess in said one portion aligned therewith being internally threaded, said interconnecting means including a pin in the other of the aligned recesses in said one and other portions and a threaded fastener extending through said one recess into threaded engagement with said threaded recess.
2. The improvement according to claim 1, wherein the ratio of the leads of said first portions to the leads of said second portions is approximately 3 to 1.
3. The improvement according to claim 1, wherein the wrap angle of each of said first and said second portions is approximately 135*.
4. In a rotary fluid compressor of the character comprising a housing having laterally communicating cylindrical chambers in which a pair of intermeshing male and female rotors are disposed for progressively compressing fluid between an inlet poRt at one end of said chambers and an outlet port at the other end of said chambers, said rotors having corresponding inlet and outlet ends with respect to said inlet and outlet ports, said male rotor having arcuately convex helical lands and said female rotor having complementary arcuately concave helical grooves, said lands and grooves being cooperable in response to rotation of said male and female rotors to progressively and continuously compress fluid between said inlet and outlet ports within a total wrap angle of the lands and grooves less than 360*, and wherein the discharge port opens into said chambers peripherally of and laterally therebetween at the discharge ends of the rotors and the lead of said lands and grooves adjacent said outlet port is less than the lead of said lands and grooves adjacent said inlet port, the improvement comprising: said male and female rotors each including structurally separate first and second portions having helical lands and grooves, said first portions extending along said rotors from said inlet ends of the rotors to a transition plane intermediate said inlet and outlet ends and transverse to the axes of said rotors, said second portions extending along said rotors from said transition plane to said outlet ends, the lands and grooves in said first portions having a constant lead, and the lands and grooves in said second portions having a constant lead which is less than the constant lead of said first portions, and means interconnecting said first and second portions of said rotors for the lands and grooves thereof to engage in mating relationship at said transition plane, said rotors including shaft means, said first portions being integral with said shaft means and said second portions being apertured to receive said shaft means, the ends of said first and second portions at said transition plane having pairs of axially aligned recesses therein, at least one of the recesses of the pair in said second portion extending completely through said second portion, and the recess in said first portion aligned therewith being internally threaded, said interconnecting means including a pin in the other of the aligned recesses in said first and second portions and a threaded fastener extending through said one recess into threaded engagement with said threaded recess.
5. The improvement according to claim 4, wherein the lead of said first portion is approximately three times the lead of said second portion and the wrap angle of each said portions is approximately 135*.
US35966573 1971-08-02 1973-05-14 Multiple lead screw compressor Expired - Lifetime US3807911A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US16802371A true 1971-08-02 1971-08-02
US35966573 US3807911A (en) 1971-08-02 1973-05-14 Multiple lead screw compressor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US35966573 US3807911A (en) 1971-08-02 1973-05-14 Multiple lead screw compressor

Publications (1)

Publication Number Publication Date
US3807911A true US3807911A (en) 1974-04-30

Family

ID=26863730

Family Applications (1)

Application Number Title Priority Date Filing Date
US35966573 Expired - Lifetime US3807911A (en) 1971-08-02 1973-05-14 Multiple lead screw compressor

Country Status (1)

Country Link
US (1) US3807911A (en)

Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4302165A (en) * 1978-08-22 1981-11-24 Imo-Industri Ab Interengaging screw machine with radial inlet and/or outlet bore
US4792294A (en) * 1986-04-11 1988-12-20 Mowli John C Two-stage screw auger pumping apparatus
US4797077A (en) * 1984-09-27 1989-01-10 Anderson Dean R G Rotary expansible chamber device
US4944657A (en) * 1989-03-01 1990-07-31 Mowli John C Two-stage pumping apparatus with low shear first stage
US4952125A (en) * 1988-04-06 1990-08-28 Hitachi, Ltd. Nonlubricated screw fluid machine
US5129276A (en) * 1989-09-28 1992-07-14 Ivg Australia Pty. Limited Meshing gear members
US5192199A (en) * 1988-10-11 1993-03-09 Svenska Rotor Maskiner Ab Machine for a gaseous medium
US5267837A (en) * 1992-09-23 1993-12-07 Mowli John C Two-stage pumping apparatus with non-meshing first stage augers
US5478210A (en) * 1992-01-31 1995-12-26 Matsushita Electric Industrial Co., Ltd. Multi-stage vacuum pump
US5667370A (en) * 1994-08-22 1997-09-16 Kowel Precision Co., Ltd. Screw vacuum pump having a decreasing pitch for the screw members
US5674063A (en) * 1994-08-19 1997-10-07 Diavac Limited Screw fluid machine and screw gear used in the same
US5709537A (en) * 1992-09-03 1998-01-20 Matsushita Electric Industrial Co., Ltd. Evacuating apparatus
DE19745615A1 (en) * 1997-10-10 1999-04-15 Leybold Vakuum Gmbh Screw vacuum pump with rotors
WO1999019630A1 (en) * 1997-10-10 1999-04-22 Leybold Vakuum Gmbh Cooled screw vacuum pump
EP0995879A1 (en) * 1998-10-23 2000-04-26 Ateliers Busch S.A. Twin feed screw rotors
US6244844B1 (en) * 1999-03-31 2001-06-12 Emerson Electric Co. Fluid displacement apparatus with improved helical rotor structure
US6257195B1 (en) 2000-02-14 2001-07-10 Arthur Vanmoor Internal combustion engine with substantially continuous fuel feed and power output
US6341951B1 (en) * 2000-05-26 2002-01-29 Industrial Technology Research Institute Combination double screw rotor assembly
US6508639B2 (en) * 2000-05-26 2003-01-21 Industrial Technology Research Institute Combination double screw rotor assembly
US20030206809A1 (en) * 2002-05-03 2003-11-06 Walker Thomas A. Method for creating an air pressure
US20050147519A1 (en) * 2003-01-15 2005-07-07 Kazuhiro Matsumoto Screw compressor and method of manufacturing rotors thereof
US20060216189A1 (en) * 2003-03-03 2006-09-28 Tadahiro Ohmi Screw vacuum pump
US20070184321A1 (en) * 2006-02-06 2007-08-09 Nucellsys Gmbh Compression device for a fuel cell stack
US20080031762A1 (en) * 2006-08-01 2008-02-07 Dieter Mosemann Screw compressor for extremely high working pressure
US20080044304A1 (en) * 2006-08-11 2008-02-21 Yuya Izawa Screw pump
US20080193315A1 (en) * 2007-02-08 2008-08-14 Kabushiki Kaisha Toyota Jidoshokki Roots-type fluid machine
US20090016920A1 (en) * 2004-06-15 2009-01-15 Shinya Yamamoto Screw pump and screw gear
US20100166591A1 (en) * 2008-12-31 2010-07-01 Kurt David Murrow Positive displacement rotary components having main and gate rotors with axial flow inlets and outlets
WO2011004257A3 (en) * 2009-07-10 2011-10-27 Robuschi S.P.A. Dry screw driver
RU2448273C2 (en) * 2009-08-03 2012-04-20 Открытое акционерное общество "УРАЛЬСКИЙ ЭЛЕКТРОХИМИЧЕСКИЙ КОМБИНАТ" Rotary screw machine
US8764424B2 (en) 2010-05-17 2014-07-01 Tuthill Corporation Screw pump with field refurbishment provisions
US20150086392A1 (en) * 2013-09-20 2015-03-26 Gardner Denver Deutschland Gmbh Dry running compressor for creating compressed air
US20160319817A1 (en) * 2014-01-15 2016-11-03 Eaton Corporation Method of optimizing supercharger performance

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB210088A (en) * 1923-01-20 1925-05-21 Georges Broulhiet Apparatus for moving fluids and capable of operating as a pump, compressor, evacuator or motor
US1597411A (en) * 1924-12-01 1926-08-24 Justus R Kinney Rotary pump
US2369539A (en) * 1942-05-02 1945-02-13 Rudolf D Delamere Displacement apparatus
US2586842A (en) * 1944-10-16 1952-02-26 Joy Mfg Co Drilling apparatus
US2652192A (en) * 1947-06-13 1953-09-15 Curtiss Wright Corp Compound-lead screw compressor or fluid motor
US2691482A (en) * 1952-07-17 1954-10-12 Equi Flow Inc Method and apparatus for compressing and expanding gases
US2804260A (en) * 1949-07-11 1957-08-27 Svenska Rotor Maskiner Ab Engines of screw rotor type
US2975963A (en) * 1958-02-27 1961-03-21 Svenska Rotor Maskiner Ab Rotor device
US3424373A (en) * 1966-10-28 1969-01-28 John W Gardner Variable lead compressor

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB210088A (en) * 1923-01-20 1925-05-21 Georges Broulhiet Apparatus for moving fluids and capable of operating as a pump, compressor, evacuator or motor
US1597411A (en) * 1924-12-01 1926-08-24 Justus R Kinney Rotary pump
US2369539A (en) * 1942-05-02 1945-02-13 Rudolf D Delamere Displacement apparatus
US2586842A (en) * 1944-10-16 1952-02-26 Joy Mfg Co Drilling apparatus
US2652192A (en) * 1947-06-13 1953-09-15 Curtiss Wright Corp Compound-lead screw compressor or fluid motor
US2804260A (en) * 1949-07-11 1957-08-27 Svenska Rotor Maskiner Ab Engines of screw rotor type
US2691482A (en) * 1952-07-17 1954-10-12 Equi Flow Inc Method and apparatus for compressing and expanding gases
US2975963A (en) * 1958-02-27 1961-03-21 Svenska Rotor Maskiner Ab Rotor device
US3424373A (en) * 1966-10-28 1969-01-28 John W Gardner Variable lead compressor

Cited By (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4302165A (en) * 1978-08-22 1981-11-24 Imo-Industri Ab Interengaging screw machine with radial inlet and/or outlet bore
US4797077A (en) * 1984-09-27 1989-01-10 Anderson Dean R G Rotary expansible chamber device
US4792294A (en) * 1986-04-11 1988-12-20 Mowli John C Two-stage screw auger pumping apparatus
US4952125A (en) * 1988-04-06 1990-08-28 Hitachi, Ltd. Nonlubricated screw fluid machine
US5064363A (en) * 1988-04-06 1991-11-12 Hitachi, Ltd. Non-lubricated screw machine with a rotor having a taper and varied helical angle
US5192199A (en) * 1988-10-11 1993-03-09 Svenska Rotor Maskiner Ab Machine for a gaseous medium
US4944657A (en) * 1989-03-01 1990-07-31 Mowli John C Two-stage pumping apparatus with low shear first stage
US5129276A (en) * 1989-09-28 1992-07-14 Ivg Australia Pty. Limited Meshing gear members
US5478210A (en) * 1992-01-31 1995-12-26 Matsushita Electric Industrial Co., Ltd. Multi-stage vacuum pump
US5709537A (en) * 1992-09-03 1998-01-20 Matsushita Electric Industrial Co., Ltd. Evacuating apparatus
US5951266A (en) * 1992-09-03 1999-09-14 Matsushita Electric Industrial Co., Ltd. Evacuating apparatus having interengaging rotors with threads having a decreasing pitch at the exhaust side
US5267837A (en) * 1992-09-23 1993-12-07 Mowli John C Two-stage pumping apparatus with non-meshing first stage augers
US5674063A (en) * 1994-08-19 1997-10-07 Diavac Limited Screw fluid machine and screw gear used in the same
EP0937895A3 (en) * 1994-08-19 2000-01-05 Diavac Limited Screw fluid machine
US5836754A (en) * 1994-08-19 1998-11-17 Diavac Limited Screw fluid machine and screw gear used in the same
EP0937895A2 (en) * 1994-08-19 1999-08-25 Diavac Limited Screw fluid machine
US5829957A (en) * 1994-08-19 1998-11-03 Diavac Limited Screw fluid machine and screw gear used in the same
US5667370A (en) * 1994-08-22 1997-09-16 Kowel Precision Co., Ltd. Screw vacuum pump having a decreasing pitch for the screw members
WO1999019631A1 (en) * 1997-10-10 1999-04-22 Leybold Vakuum Gmbh Screw vacuum pump provided with rotors
WO1999019630A1 (en) * 1997-10-10 1999-04-22 Leybold Vakuum Gmbh Cooled screw vacuum pump
DE19745615A1 (en) * 1997-10-10 1999-04-15 Leybold Vakuum Gmbh Screw vacuum pump with rotors
US6544020B1 (en) 1997-10-10 2003-04-08 Leybold Vakuum Gmbh Cooled screw vacuum pump
US6382930B1 (en) 1997-10-10 2002-05-07 Leybold Vakuum Gmbh Screw vacuum pump provided with rotors
EP0995879A1 (en) * 1998-10-23 2000-04-26 Ateliers Busch S.A. Twin feed screw rotors
WO2000025004A1 (en) * 1998-10-23 2000-05-04 Ateliers Busch S.A. Twin helical rotors for installation in displacement machines for compressible media
CN1113151C (en) * 1998-10-23 2003-07-02 阿特里尔斯布希股份有限公司 Twin helical rotors installated in displacement machines for compressible media
US6447276B1 (en) 1998-10-23 2002-09-10 Ateliers Busch Sa Twin screw rotors for installation in displacement machines for compressible media
US6244844B1 (en) * 1999-03-31 2001-06-12 Emerson Electric Co. Fluid displacement apparatus with improved helical rotor structure
US6530365B2 (en) 1999-05-18 2003-03-11 Arthur Vanmoor Fluid displacement pump with backpressure stop
US6257195B1 (en) 2000-02-14 2001-07-10 Arthur Vanmoor Internal combustion engine with substantially continuous fuel feed and power output
US6341951B1 (en) * 2000-05-26 2002-01-29 Industrial Technology Research Institute Combination double screw rotor assembly
US6508639B2 (en) * 2000-05-26 2003-01-21 Industrial Technology Research Institute Combination double screw rotor assembly
US20030206809A1 (en) * 2002-05-03 2003-11-06 Walker Thomas A. Method for creating an air pressure
US20050147519A1 (en) * 2003-01-15 2005-07-07 Kazuhiro Matsumoto Screw compressor and method of manufacturing rotors thereof
US7040845B2 (en) * 2003-01-15 2006-05-09 Hitachi Industries Co., Ltd. Screw compressor and method of manufacturing rotors thereof
US20060216189A1 (en) * 2003-03-03 2006-09-28 Tadahiro Ohmi Screw vacuum pump
US7744356B2 (en) * 2003-03-03 2010-06-29 Foundation For Advancement Of International Science Screw vacuum pump with male and female screw rotors having unequal leads
US20090016920A1 (en) * 2004-06-15 2009-01-15 Shinya Yamamoto Screw pump and screw gear
US20070184321A1 (en) * 2006-02-06 2007-08-09 Nucellsys Gmbh Compression device for a fuel cell stack
US20080031762A1 (en) * 2006-08-01 2008-02-07 Dieter Mosemann Screw compressor for extremely high working pressure
US7753665B2 (en) * 2006-08-01 2010-07-13 Grasso Gmbh Refrigeration Technology Screw compressor for working pressures above 80 bar
US20080044304A1 (en) * 2006-08-11 2008-02-21 Yuya Izawa Screw pump
US7484943B2 (en) * 2006-08-11 2009-02-03 Kabushiki Kaisha Toyota Jidoshokki Screw pump with improved efficiency of drawing fluid
US20080193315A1 (en) * 2007-02-08 2008-08-14 Kabushiki Kaisha Toyota Jidoshokki Roots-type fluid machine
US20100166591A1 (en) * 2008-12-31 2010-07-01 Kurt David Murrow Positive displacement rotary components having main and gate rotors with axial flow inlets and outlets
CN101769165A (en) * 2008-12-31 2010-07-07 通用电气公司 Positive displacement gas turbine engine with parallel screw rotors
CN101769165B (en) * 2008-12-31 2014-10-29 通用电气公司 Positive displacement gas turbine engine with parallel screw rotors
US8328542B2 (en) * 2008-12-31 2012-12-11 General Electric Company Positive displacement rotary components having main and gate rotors with axial flow inlets and outlets
WO2011004257A3 (en) * 2009-07-10 2011-10-27 Robuschi S.P.A. Dry screw driver
CN102575673B (en) * 2009-07-10 2015-12-16 嘉德纳丹佛有限责任公司 Dry screw driver
CN102575673A (en) * 2009-07-10 2012-07-11 罗布斯基股份公司 Dry screw driver
RU2448273C2 (en) * 2009-08-03 2012-04-20 Открытое акционерное общество "УРАЛЬСКИЙ ЭЛЕКТРОХИМИЧЕСКИЙ КОМБИНАТ" Rotary screw machine
US8764424B2 (en) 2010-05-17 2014-07-01 Tuthill Corporation Screw pump with field refurbishment provisions
US20150086392A1 (en) * 2013-09-20 2015-03-26 Gardner Denver Deutschland Gmbh Dry running compressor for creating compressed air
US20160319817A1 (en) * 2014-01-15 2016-11-03 Eaton Corporation Method of optimizing supercharger performance

Similar Documents

Publication Publication Date Title
US3289602A (en) Fluid pressure device
US3787154A (en) Rotor profiles for helical screw rotor machines
US4741681A (en) Gerotor motor with valving in gerotor star
KR0133154B1 (en) Screw pump
US3874828A (en) Rotary control valve for screw compressors
US3680989A (en) Hydraulic pump or motor
US20040247465A1 (en) Screw type vacuum pump
US3151806A (en) Screw type compressor having variable volume and adjustable compression
US2866417A (en) Rotary piston machine
US2287716A (en) Fluid device
US3677664A (en) Rotary mechanical pumps of the screw type
US3834842A (en) Hydraulic power translating device
US7802974B2 (en) Screw compressor having asymmetric seal around rotor axis
EP0183380B1 (en) Positive-displacement screw pump
US3551082A (en) Globoid-worm compressors
US3088659A (en) Means for regulating helical rotary piston engines
US3462072A (en) Screw rotor machine
US4042310A (en) Screw compressor control means
US6497564B2 (en) Balanced rotors positive displacement engine and pump method and apparatus
GB2358438A (en) Multi-stage scroll pump or compressor
EP0769104B1 (en) Helical gear pump or motor
US2649740A (en) High-pressure pump
US3560119A (en) Fluid pump or motor
US6776594B1 (en) Rotor mechanism
FR2512105A1 (en) Rotor profiles with blades or helical branches

Legal Events

Date Code Title Description
AS Assignment

Owner name: AERO-DRI CORPORATION, A CORP. OF OH.

Free format text: LICENSE;ASSIGNOR:WELLS FARGO BUSINESS CREDIT;REEL/FRAME:004487/0379

Effective date: 19850614

Owner name: DAVEY COMPRESSOR COMPANY, AN OHIO CORP.

Free format text: LICENSE;ASSIGNOR:WELLS FARGO BUSINESS CREDIT;REEL/FRAME:004487/0379

Effective date: 19850614

Owner name: WELLS FARGO BUSINESS CREDIT, XEROX BUILDING, SUITE

Free format text: SECURITY INTEREST;ASSIGNORS:DAVEY COMPRESSOR COMPANY, A CORP. OF OH.;AERO-DRI CORPORATION, A CORP. OF OH.;REEL/FRAME:004487/0367

Effective date: 19850614

AS Assignment

Owner name: AERO-DRI CORPORATION, A OHIO CORP.

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:WELLS FARGO BUSINESS CREDIT, A CA. CORP.;REEL/FRAME:004678/0446

Effective date: 19861222

Owner name: INDIANA NATIONAL BANK, THE, 11311 CORNELL PARK DRI

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:DAVEY COMPRESSOR COMPANY;AERO-DRI CORPORATION;REEL/FRAME:004663/0466

Effective date: 19861222

AS Assignment

Owner name: FIRST NATIONAL BANK OF CINCINNATI, THE, 425 WALNUT

Free format text: LICENSE;ASSIGNOR:DAVEY COMPRESSOR COMPANY;REEL/FRAME:004812/0207

Effective date: 19871006

AS Assignment

Owner name: DAVEY COMPRESSOR COMPANY, 11060 KENWOOD ROAD, CINC

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:INDIANA NATIONAL BANK;REEL/FRAME:004849/0371

Effective date: 19871006

Owner name: AERO-DRI CORPORATION, 11060 KENWOOD ROAD, CINCINNA

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:INDIANA NATIONAL BANK;REEL/FRAME:004849/0371

Effective date: 19871006

Owner name: DAVEY COMPRESSOR COMPANY,OHIO

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:INDIANA NATIONAL BANK;REEL/FRAME:004849/0371

Effective date: 19871006

Owner name: AERO-DRI CORPORATION,OHIO

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:INDIANA NATIONAL BANK;REEL/FRAME:004849/0371

Effective date: 19871006

AS Assignment

Owner name: DAVEY COMPRESSOR COMPANY, OHIO

Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:STAR BANK, NATIONAL ASSOCIATION, CINCINNATI;REEL/FRAME:005597/0238

Effective date: 19901203

AS Assignment

Owner name: FULLER COMPANY, 2040 AVE., C, LVIP, P.O. BOX 2040

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DAVEY COMPRESSOR COMPANY;REEL/FRAME:005576/0550

Effective date: 19901203

AS Assignment

Owner name: BANK OF AMERICA, NATIONAL ASSOCIATION, AS AGENT, M

Free format text: SECURITY INTEREST;ASSIGNOR:KECO INDUSTRIES, INC.;REEL/FRAME:010395/0672

Effective date: 19990930

AS Assignment

Owner name: BANK OF AMERICA, N.A., MISSOURI

Free format text: RELEASE;ASSIGNOR:KECO INDUSTRIES, INC.;REEL/FRAME:014007/0333

Effective date: 20030423

AS Assignment

Owner name: KECO INDUSTRIES, INC., MISSOURI

Free format text: TERMINATION OF SECURITY INTEREST;ASSIGNOR:BANK OF AMERICA, N.A., AS AGENT;REEL/FRAME:014709/0461

Effective date: 20030423