US3602346A

US3602346A - Adjustable clutch

Info

Publication number: US3602346A
Application number: US4997A
Authority: US
Inventors: Donald E Daugherty
Original assignee: Sperry Rand Corp
Current assignee: Sperry Corp
Priority date: 1970-01-22
Filing date: 1970-01-22
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31

Abstract

A mechanism for transmitting motion from a prime mover, such as a motor or the like, to a pair of independent output shafts having different torsional characteristics. A driving member is rotated by the prime mover at a constant speed. This motion is controllably transmitted to a pair of driven assemblies which include the mentioned output shafts. Coupling between the driving member and the driven assemblies provides for shaft slippage under conditions where predetermined torque is exceeded. To this end, independently adjustable coupling devices are associated with respective driven assemblies.

Description

United States Patent Donald E. Daugherty Marietta, Ohio Jan. 22, 1970 Aug. 31, 1971 Sperry Rand Corporation New York, N.Y.

[72] Inventor [21] Appl. No. [22] Filed [45] Patented [73] Assignee [54] ADJUSTABLE CLUTCH 8 Claims, 3 Drawing Figs.

[52] US. Cl 192/483, 64/30 C. 64/30 LB, 242/569, 287/129 [51] 1nt.C1 ..F16d 21/06, F16d 7/02 [50] Field of Search 64/30 R, 30 C, 30 A, 30 LB; 192/488, 56 R, 49; 242/569; 287/129, 130

[56] References Cited UNITED STATES PATENTS 755,952 3/1904 Smith 64/30 R 1,236,669 8/1917 Burt 64/30 R (X) 1,880,344 10/1932 Franco 192/49 2,226,759 12/1940 Fitzner 192/49 (X) 2,545,960 3/1951 Kuehn 64/30 LB 3,105,371 10/1963 Forrest... 64/3OC 3,199,312 8/1965 Glasgow 64/30 R (X) 3,430,743 3/1969 Fujita et a1 192/488 (X) 3,434,303 3/1969 Leyer 287/129 (X) Primary Examiner-AHan D. Herrmann Auorneys- Frank A. Seemar, Marshall M. Truex and Thomas P. Murphy ABSTRACT: A mechanism for transmitting motion from a prime mover, such as a motor or the like, to a pair ofindependent output shafts having different torsional characteristics. A driving member is rotated by the prime mover at a constant speed. This motion is controllably transmitted to a pair of driven assemblies which include the mentioned output shafts. Coupling between the driving member and the driven assemblies provides for shaft slippage under conditions where predetermined torque is exceeded. To this end, independently adjustabIe coupling devices are associated with respective driven assemblies.

PATENTED Ausal 19'1":

SHEET 2 [IF 2 ADJUSTABLE CLUTCH BACKGROUND OF THE INVENTION The present invention relates to a motion transmitting mechanism and more particularly to a frictional clutch assembly having two output members driven by a common input member.

Rapid growth of the microfilm field has given rise to many problems, not the least of which is the need for efficient and economical photographic apparatus for accurately minifying documents while maintaining strict reproduction standards. It is not uncommon for institutional users of microfilm to require apparatus adapted to sequentially reproduce documents on two separate rolls of films, simultaneously, at relatively high rates of speed. One roll of film is normally used for everyday purposes while the other is retained for archival storage. The type of apparatus that accomplishes dual simultaneous reproduction is commonly referred to as a dual action camera.

In a typical microfilm camera, film is initially transferred from a fully loaded idler reel to an empty takeup reel. It is desirable to maintain the film speed constant and accordingly the idler reel speed must be progressively increased as the film I is expended therefrom. To this end, a drag or frictional force is usually employed to prevent the idler from loosely feeding film as the reel speed increases. Likewise, the converse reasoning applies with respect to takeup and thus the speed of the driven takeup reel must be progressively decreased. This is normally accomplished by accurately presetting 'the drive coupling to cooperate with the idler reel drag setting. The motion transmitting mechanism of the present invention is an example of this type of adjustable coupling device.

As mentioned above, it is generally desirable in microfilm cameras to drive film along an optical path at a constant speed and in a taunt condition. In the case of dual action cameras, for the purposes of synchronized shutter action, it is also desirable to drive the takeup reels by a common source even though reel loads vary due to differing torque conditions present at each spindle. These needs have given rise to the present invention which provides improved apparatus for independently adjusting takeup reels driven by a common prime mover in systems in which varying torsional characteristics prevail.

. The importance of accurately presetting friction coupling for a pair of commonly driven takeup reels in a microfilm camera becomes even more obvious when consideration is given to the potential results of a jammed film box due to lack of proper coupling between the reels and a common input driver element. On the other hand, if an operator attempts to avoid jams by indiscriminately increasing the takeup reel speed and idler drag concurrently, the film will become too taunt and broken film will result.

It is therefore an object of the present invention to provide a unique motion transmitting mechanism for driving a pair of output members from a common source.

Another object is to provide a novel mechanism for coupling one input member to two independently adjustable output members.

A further object is to provide a novel frictional coupling mechanism capable of operating at a relatively high rate of speed under continuously varying torsional conditions to provide transmission of motion from an input member to a pair of independently adjustable output members.

BRIEF DESCRIPTION OF THE INVENTION The present invention contemplates a motion transmitting mechanism for coupling an input member to a pair of independent output members having varying torsional characteristics. In the preferred embodiment, an input member having a pair of parallel planar faces transmits motion to first and second driven members each of which comprise an output element and a clutching element. The input member and driven members are mounted along a common axis with the driven members on opposite sides' of the input member. Each output element comprises a shaft extending outwardly from the input member and each clutching element comprises a flange portion integrally associated with a particular shaft and including a flat surface in parallel with the corresponding planar surface of the input member. Frictional coupling devices couple the fiat surfaces of the clutching elements to the planar surfaces of the input member such that the first and second driven members respond in concert to rotation of the input member, whereby the output shafts are independently driven.

More specifically, frictional coupling is effected independently for each driven member by an adjustable device that urges the respective clutching element toward the corresponding planar surface of the input member. Variable frictional engagement thereby results. Further details of the structure of these coupling arrangements are set forth in the description hereinbelow.

The foregoing and other objects, features and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, in conjunction with the accompanying drawings wherein one embodiment of the invention is illustrated by way of example.

. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective exploded view illustrating the structure of one embodiment of the present invention and the relationship of variouselements thereof.

FIG. 2 is an end view of thestructure shown in FIG. 1, in an assembled condition.

FIG. 3 is a sectional'view taken along line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to the drawings in which a preferred embodiment of the present invention is depicted, the elements of a motion transmitting mechanism are shown in FIG. 1 in exploded fashion to illustrate various interrelationships thereof. A spur gear 10 is the driving member of the mechanism and is adapted to be coupled to a prime mover, such as a motor, by means of a gear train (not shown) or other means for rotatably transferring motion thereto. Gear 10 is coupled to a pair of driven members, comprising spindle assemblies 11 and 11', having

integral shaft elements

12 and 12 respectively. In view of the similarity between first and'second groups of elements of the present invention, primed reference numerals will be utilized for designation thereof, the clarifying effect of which will become apparent hereinafter.

More specifically, gear 10 and shaft elements 12 and 120 (also see FIGS. 2 and 3) are mounted in coaxial relationship on a dowel pin 13, constructed in the preferred embodiment from stainless steel. Although other similar materials could be substituted for this element, the preferred material is specified. In a like fashion, the material or materials will be set forth from which most of the elements described hereinafter may be fabricated; however, it is to be understood that it is not intended that any element by limited to the specified materials. Pin 13 extends outwardly from gearIO (brass) into axially disposed cavities l4 and 14 (FIG. 3) located in elements 12 and 1240 The diameters of cavities l4 and 14', as well as the center hole through gear 10, are slightly greater than the diameter of pin 13 to the extent that there is a snug fit between the assembled parts and wobbling is substantially obviated. The degree of clearance is not critical, as will become evident from the description hereinafter.

Washers

15 and 15 are disposed in axial alignment with pin 13 which extends throughcentrally located clearance holes in these washers. Similar washers l6 and 16' are mounted on shaft elements 12 and'12', respectively, by'virtue of central clearance holes with diameters exceeding the outer diameters ofshaft elements 12 and 12', respectively. Washers l5, l5, l6 and 16' are constructed from a thermoplastic resin material, preferably a plastic of the polytetrafluro-ethylene type of flurocarbon. The latter substance is commonly known and sold under the trademark Teflon. The properties of Teflon plastics are well known and include favorable resistivity to extreme temperatures, excellent dielectrical qualities, high impact strength and low coefficient of friction. These properties are especially desirable in view of the characteristics of the elements for which they are intended, as is clearly set forth in the operative description hereinbelow.

The spindle assemblies 11 and 11' comprise disc-shaped flange elements 17 and 17', fabricated from steel and plated with chrome, and sandwiched between the above-described Teflon washers in the manner illustrated in FIG. 1 and shown in section in FIG. 3. Further included in the coupling assembly are

aluminum retainer members

18 and 18 secured to gear by a series of screws 20 and 20' alternately facing opposite portions of gear 10. The screws pass through clearance holes in the associated retainer members and are secured in threaded holes in gear 10, which holes register with the corresponding clearance holes in the opposing retainer members. Retainers l8 and 18 include inwardly facing

walls

21 and 21, respectively, (see FIG. 3) bearing against

spring washers

22 and 22 which in turn

urge brass washers

23 and 23 against the outer surfaces of Teflon washers l6 and 16. The spring washers, constructed from bronze in the preferred embodiment, and the brass washers are axially mounted along

elements

12 and 12 with centrally located clearance holes having diameters exceeding the outer diameters of

elements

12 and 12'. v

To complete the description of elements in the preferred embodiment, it should be noted that the spindle assembly is adapted to accommodate a film reel or the like. Shoulders 24 and 24' (FIGS. 2 and 3 only) extend from shaft elements 12 and '12, and spring-biased

reel retainer bearings

25 and 25 protrude from diametric holes at a flattened portion of the respective shafts.

In operation, the present invention may be employed as a motion transmitting mechanism regardless of the field of intended use. Adjustable friction coupling is provided between a single drive member and independently controlled output members, such as driven spindles for microfilm takeup reels. Referring to FIG. 3, reels (not Shown) are mounted on shaft elements 12 and 12' to perform dual takeup functions in a duplex camera. The reels are positioned against shoulders 24 and 24' by the biased bearings 25 and 25' in a conventional manner, whereby each shaft and reel rotate in unison. As mentioned above, the takeup reels are driven in a manner such that the film travels at a constant speed; however, factors contributing to drag vary to a certain degree which results in unequal torque characteristics. To this end, the invention contemplates independent slip clutch coupling between the common spur gear 10 and output shafts elements '12 and 12', each clutch being initially adjusted for a predetermined design load and later readjusted for prevailing operating conditions.

Now turning to more specific operative details involved in the adjustment of the left (FIGS. 1 and 2) clutch assembly for exemplary purposes, screws 20 are inserted through the holes in retainer member 18 and into registering threaded holes in gear 10. An equal torque is applied to the four screws to evenly distribute pressure from wall 21 against spring washer 22, which in turn is urged against washer 23 to press the inwardly facing surface thereof against Teflon washer 16. This pressure is transmitted to the outwardly facing surface of gear 10 via flange l7 and Teflon washer in a sandwich like fashion, resulting in frictional engagement between, gear 10 and the inwardly facing surface of washer 15, the outwardly facing surface of washer l5 and the inwardly facing surface of flange 17, the inwardly facing surface of washer l6 and the outwardly facing surface of flange l7, and the outwardly facing surface of ring 16 and the inwardly facing surface of ring 23. These four frictionally coupled pairs surfaces surface provide slip coupling between gear 10 and shaft 12, which coupling may be adjusted by varying the pressure applied against spring washer 22 by retainer member 18, which results in a change in the pressure exerted against flange 11 by

ring elements

15 and 16. The latter two elements are preferably fabricated from Teflon or a like plastic having similar properties which include a low coefficient of friction, thereby enhancing the ability to accurately adjust the frictional coupling to desired loading conditions.

Many advantages of the present invention are implicitly and explicitly described above, however, it should be emphasized that the novel features of the above-described clutch structure obviate binding, misalignment and overloaded conditions. Moreover, the advantages of simplicity and economy have not been stressed without due consideration being given to favorable and safe operating characteristics.

Although a specific embodiment of the invention has been illustrated and described in detail by way of example, it is to be understood that the invention is not limited thereto. Various changes may be made in the design and arrangement of parts without departing from the spirit and scope of the invention, as will be readily understood by those skilled in the art.

I claim:

1. A motion transmitting mechanism comprising,

a. an input member having a pair of parallel planar faces,

b. first and second driven members, each comprising an output element and a clutching element,

c. means for mounting said input member and said first and second driven members along a common axis with said driven members on opposite sides of said input member,

d. said output element comprising shaft means extending outwardly from said input member,

c. said clutching element comprising a flange portion integrally associated with said shaft means and including a flat surface in parallel with the corresponding planar surface of said input member, frictional means for coupling the flat surface of said clutching element to the planar surface of said input member whereby said first and second driven members respond in concert to rotation of said input member, and

g. said frictional coupling means including means for urging said clutching element toward the planar surface of said input member, and. adjusting means for varying the amount of pressure exerted by said urging means, whereby the frictional engagement is independently adjustable for each respective driven member.

2. A motion transmitting mechanism as set forth in claim 1 wherein said urging means comprise a retainer member having an inner surface facing said flange portion,

a spring washer element disposed in axial alignment with said input member'and said driven members and disposed between the inner surface of said retainer member and said flange portion, whereby said adjusting means is adapted for urging the retainer member inwardly against said input member such that pressure is exerted by the spring washer against the flange portion and the flange portion in turn is urged against said input member, which pressure is presettable to provide for slippage under conditions where a predetermined torque is exceeded under operating conditions of the corresponding output shaft.

3. A motion transmitting mechanism as set forth in claim 2 wherein said urging means further comprise a metal washer disposed coaxially inwardly from said spring washer,

a first plastic washer disposed coaxially inwardly from said metal washer and outwardly from said flange portion, and

a second plastic washer disposed inwardly from said flange portion and outwardly from the adjacent planar face of said input member, whereby the inwardly facing and outwardly facing surfaces respectively of said first and second plastic washers provide the clutching surfaces of said mechanism.

4. A motion transmitting mechanism as set forth in claim 3 wherein said first and second plastic washers are constructed from a thermoplastic resin.

5. A motion transmitting mechanism comprising,

a. an input member having a pair of parallel planar faces,

a retainer member having as inner surface facing said flange b. first and second driven members, each comprising an output element and a clutching element, portion, I 0. means for mounting said input member and said first and a spring washer element disposed in axial alignment with second driven members along a common axis with said said input member and said driven members and disposed driven members on opposite sides of said input member, 5 'between the inner surface of said retainer member and d. said output element comprising shaft means extending said flange portion, whereby said adjusting means is outwardly from said input member and coaxially with adapted for urging the retainer member inwardly against respect to said common axis, said input member such that pressure is exerted by the e. said clutching element comprising a flange portion inp ng W h r against he flange portion and the flange tegrally associated with said shaft means and including a 10 p i n rn is urged against said input member, which flat surface in parallel with the corresponding planar sur- Pressure IS Presettable I prov de he slippage under conface of said input member, ditions where a predetermined torque is exceeded under f. frictional means for coupling the flat surface of said Operatmg condltions of the corresponding output Shaftclutching element to the planar rfa f Said input 7. A motion transmitting mechanism as set forth in claim 6 member whereby said first and second driven members Wherem 531d urgmg means f" f p respond in concert to rotation of said input member, a metal Washer disposed caxlally inwardly from 531d spring g. a pin member extending along said common axis and pro- Washer,

jecting through the centers of said input member and said a first Plastic Washer dlsposed coaxiaily mwardly from 531d first and second driven members and terminating within a metal Washef and outwafdly frofn Said flange P E and centrally disposed cavity in the shaft means of said first a secofid Plastlc Washer dlsposed mwafdly 0m 531d flange and second driven members and portion and outwardly from the ad acent planar face of h. said frictional coupling means including means for urging Sald Input "f whereby the i y faQmg and said clutching element toward the planar surface of said wardly facllig Surfaces resPecnvely of first and input member, and adjusing means for varying the second plastic washers provide the clutching surfaces of amount of pressure exerted by said urging means, said i I whereby the frictional engagement is independently 8. motion transmitting mechanism as set forth m claim 7 justable for each respective driven member wherein said first and second plastic washers are constructed 6. A motion transmitting mechanism as set forth in claim 5 from a thermoplasnc resm' wherein said urging means comprise

Claims

1. A motion transmitting mechanism comprising, a. an input member having a pair of parallel planar faces, b. first and second driven members, each comprising an output element and a clutching element, c. means for mounting said input member and said first and second driven members along a common axis with said driven members on opposite sides of said input member, d. said output element comprising shaft means extending outwardly from said input member, e. said clutching element comprising a flange portion integrally associated with said shaft means and including a flat surface in parallel with the corresponding planar surface of said input member, f. frictional means for coupling the flat surface of said clutching element to the planar surface of said input member whereby said first and second driven members respond in concert to rotation of said input member, and g. said frictional coupling means including means for urging said clutching element toward the planar surface of said input member, and adjusting means for varying the amount of pressure exerted by said urging means, whereby The frictional engagement is independently adjustable for each respective driven member.

2. A motion transmitting mechanism as set forth in claim 1 wherein said urging means comprise a retainer member having an inner surface facing said flange portion, a spring washer element disposed in axial alignment with said input member and said driven members and disposed between the inner surface of said retainer member and said flange portion, whereby said adjusting means is adapted for urging the retainer member inwardly against said input member such that pressure is exerted by the spring washer against the flange portion and the flange portion in turn is urged against said input member, which pressure is presettable to provide for slippage under conditions where a predetermined torque is exceeded under operating conditions of the corresponding output shaft.

3. A motion transmitting mechanism as set forth in claim 2 wherein said urging means further comprise a metal washer disposed coaxially inwardly from said spring washer, a first plastic washer disposed coaxially inwardly from said metal washer and outwardly from said flange portion, and a second plastic washer disposed inwardly from said flange portion and outwardly from the adjacent planar face of said input member, whereby the inwardly facing and outwardly facing surfaces respectively of said first and second plastic washers provide the clutching surfaces of said mechanism.

5. A motion transmitting mechanism comprising, a. an input member having a pair of parallel planar faces, b. first and second driven members, each comprising an output element and a clutching element, c. means for mounting said input member and said first and second driven members along a common axis with said driven members on opposite sides of said input member, d. said output element comprising shaft means extending outwardly from said input member and coaxially with respect to said common axis, e. said clutching element comprising a flange portion integrally associated with said shaft means and including a flat surface in parallel with the corresponding planar surface of said input member, f. frictional means for coupling the flat surface of said clutching element to the planar surface of said input member whereby said first and second driven members respond in concert to rotation of said input member, g. a pin member extending along said common axis and projecting through the centers of said input member and said first and second driven members and terminating within a centrally disposed cavity in the shaft means of said first and second driven members, and h. said frictional coupling means including means for urging said clutching element toward the planar surface of said input member, and adjusting means for varying the amount of pressure exerted by said urging means, whereby the frictional engagement is independently adjustable for each respective driven member.

6. A motion transmitting mechanism as set forth in claim 5 wherein said urging means comprise a retainer member having as inner surface facing said flange portion, a spring washer element disposed in axial alignment with said input member and said driven members and disposed between the inner surface of said retainer member and said flange portion, whereby said adjusting means is adapted for urging the retainer member inwardly against said input member such that pressure is exerted by the spring washer against the flange portion and the flange portion in turn is urged against said input member, which pressure is presettable to provide the slippage under conditions where a predetermined torque is exceeded under operating conditions of the corresponding output shaft.

7. A motion transmitting mechanism as set forth in claim 6 wherein said urGing means further comprise a metal washer disposed coaxially inwardly from said spring washer, a first plastic washer disposed coaxially inwardly from said metal washer and outwardly from said flange portion, and a second plastic washer disposed inwardly from said flange portion and outwardly from the adjacent planar face of said input member, whereby the inwardly facing and outwardly facing surfaces respectively of said first and second plastic washers provide the clutching surfaces of said mechanism.

8. A motion transmitting mechanism as set forth in claim 7 wherein said first and second plastic washers are constructed from a thermoplastic resin.