US3533299A

US3533299A - Directional drive mechanism

Info

Publication number: US3533299A
Application number: US800514A
Authority: US
Inventors: Henry Timmer
Original assignee: TRANSIGN Inc
Current assignee: TRANSIGN Inc
Priority date: 1969-02-19
Filing date: 1969-02-19
Publication date: 1970-10-13
Anticipated expiration: 1987-10-13

Description

Oct. 13, 1970 H. TIMMER DIRECTIONAL DRIVE MECHANISM 2 Shouts-Sheet 1 Filed Feb. 19, 1969 INVENTOR HEN/P) T/MME/P 0a. 13,1910 H. TIMMER 3,533,299

DIRECTIONAL DRIVE MECHANISM Filed Feb. 19, 1969 2 Sheets-Sheet 2 g /iw FZHL/ 3,533,299 DIRECTIONAL DRIVE MECHANISM Henry Timmer, Grand Rapids, Mich., assignor to Transign, Inc., Pontiac, Mich. Filed Feb. 19, 1969, Ser. No. 800,514 Int. Cl. B6511 17/02; F16d 11/06; F16h 57/00 US. Cl. 74-405 8 Claims ABSTRACT OF THE DISCLOSURE A rotary directional drive transferring driving torque exclusively in one direction independently of the presence or absence of a tendency of the driving and driven members to exhibit relative overrunning rotation from outside influences. An intermediate torque-transfer member is adapted to lock to the driven member exclusively when driving-director torque is applied by the driving member.

BACKGROUND OF THE INVENTION Power-transfer mechanisms must frequently be adapted to the application of torque exclusively in one rotational direction. This requirement is commonly met by the use of an overrunning clutch or some form of a ratchet drive. An example of such an application is the usual starter mechanism, in which torque is applied for short periods to provide enough rotation of an internal combustion engine to begin its normal operation. Once the engine begins to run, its rotational speed is normally in excess of that provided by the starter, and it overruns the starting drive. The characteristic of this form of mechanism is that the torque is transferred through the starting drive as long as the driven member is not moving faster than the driving member in the same direction at the point of interengagement. In most applications, this presence or absence of an overrunning condition corresponds exactly to the conditions under which torque must be supplied.

Applications are occasionally encountered, however, where the delivery of torque must not always correspond to the mere presence or absence of an overrunning condition. One such application is in the mechanism used for positioning the scrolls of a destination sign. These signs are commonly associated with buses, streetcars, and local trains to indicate the particular destination to passengers about to board. Essentially, these signs include a pair of rollers on which a long strip of fabric is wound in the manner of a scroll. The fabric is printed with a sequence of destinations, and the sign is equipped with a drive mechanism capable of rotating the scrolls in either direction so that any particular portion of it may be exposed at the viewing point. The driving mechanism obviously must be adapted to move the scrolls in either direction, and it is here that the problem arises. It is common practice to use either a chain or a geared driving mechanism interrelating the rolls with a manual or powered actuating mechanism, and provisions must necessarily be made for the fact that at almost all occasions there will be more fabric wound on one roll than on the other. Since the linear velocity of the fabric is the same; it is clear that at any given moment there will be a different angular velocity of one roll than for the other to produce a given linear velocity of the fabric. This is true regardless of the direction of rotation that the operator wishes to induce in the rolls. With most of the fabric accumulated on one of the scroll rollers, a driving action in either direction will induce a more rapid rate of rotation of the opposite scroll roller than that of the roller on which the bulk of the fabric has accumulated. The design problem confronting the engineer at this point is the provision of United States Patent "ice a directional drive mechanism that can be associated with each roller so that power can be delivered from a central point through a gear train associating both rollers without inducing a jamming action under any conditions. It is clear that a mere overrunning mechanism, which would interconnect a driving relationship purely as a function of an overrunning condition, will not work. Such a mechan ism would induce a driving connection to both rollers at the same time, in which it would be impossible to accommodate a different winding diameter. The US. Pat. No. 3,073,542, issued to John Kaashoek in March of 1960 is an example of the form of mechanism referred to in this discussion. The disclosure of this application may be considered as an improvement on the Kaashoek mechanism.

SUMMARY OF THE INVENTION The driving mechanism provided by this invention has the characteristic of transferring torque as a function of the presence or absence of the initial delivery of torque, rather than in response to the presence or absence of an overrunning condition. In the preferred form of this invention, an intermediate member is mechanically interposed between a driving and a driven member, which are coaxially mounted for both relative and joint rotation. An actuator carried by the intermediate member is positioned by the application of torque from the driving member so that it moves to a position to intersect an abutment on the driven member. Under these conditions, a driving relationship is established through the mechanism for the delivery of torque in a particular rotational direction. In the absence of driving torque, the actuator remains in a retracted position clear of the abutment, which permits the driven member to rotate independently of the intermediate and drive members. A braking mechanism effective between the intermediate and driven members establishes enough resistance to relative rotation between these components to induce the extension of the actuator into driving position. This same braking mechanism is also utilized, in the preferred form of the invention, to establish a resistance to rotation of the roller for the main- 4 tenance of winding tension in the fabric of a directional sign mechanism so that the driven roller will have some degree of pulling action to maintain a desired degree of tautness in the fabric.

DESCRIPTION OF THE DRAWINGS The several features of the invention will be analyzed in detail through a discussion of the particular embodiment illustrated in the accompanying drawings. In the drawings:

FIG. 1 is a sectional elevation through a destination sign mechanism provided with the directional drive systems embodying this invention.

FIG. 2 is a sectional view on an enlarged scale on the plane 2-2 of FIG. 1.

FIG. 3 is a sectional view on an enlarged scale on the plane 33 of FIG. 1.

FIG. 4 is a view illustrating the driving condition of the mechanism shown in FIG. 3.

FIG. 5 is a view illustrating the inactive condition of the mechanism shown in FIG. 3.

FIG. 6 is a view on an enlarged scale, taken on an axial plane, showing the mounting of the actuator on the intermediate member.

FIG. 7 is a perspective view showing the driven member of the mechanism, on an enlarged scale.

FIG. 8 is a section on the plane 8-8 of FIG. 7.

FIG. 9 is a section on the plane 99 of FIG. 7.

FIG. 10 is an end view on the inside face of the intermediate member showing the mounting of the actuator.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT The destination sign mechanism shown in FIG. 1 includes a frame generally indicated at providing support for the rotatably-mounted

rollers

21 and 22. These rollers are in scroll relationship, a long strip of printed fabric presenting sign designations being wound at opposite ends on these rollers, and trained from the roller 21 around the

guide rollers

23 and 24. A light bracket 25 provides a convenient mounting platform for bulbs of any desired description, and is supported on the

rods

26 and 27 secured at opposite ends to the frame structure 20. Tabs as indicated at 28 on the frame 20 may be used for mounting the entire assembly in a vehicle. The unit is usually installed in such a position that the space between the

guide rollers

23 and 24 is opposite a viewing window in the front or side of the vehicle.

Each of the

rollers

21 and 22 is equipped with a similar torque-transfer mechanism which includes the

spur gears

29 and 30, respectively. The

idler gears

31 and 32 ar respectively mounted on

stub shafts

33 and 34, and these idlers mesh both with the gears 29 and and with the central gear 35 appearing most clearly in FIG. 2. The gear 35 and the bevel gear 36 are both secured to the tubular member 37 rotatably mounted on the shaft 38, the position of the gears being secured by the set screws indicated at 39 and 40. The mating bevel gear 41 is secured to the shaft 42 rotatably mounted in the

bearings

43 and 44 carried by the bracket 45 and the frame 20, respectively. The shaft 42 extends out to a sufficient length to receive the wheel crank 46, with which the sign mechanism is adjusted. The manual torque delivered to the crank wheel 46 is delivered through the gear train and the torque-transfer mechanism associated with each roller to position the fabric strip carrying the sign indicia.

The selective torque-transfer mechanisms associated with the

rollers

21 and 22 are both alike, and are shown in FIGS. 3 through 6. The rollers each includes a tubular member 47 which receives the sign fabric, and opposite end plugs as shown at 48. These end plugs are rotatably received on the shafts 49. FIG. 3 illustrates the driving end of the rollers, the opposite end being provided merely with a rotatable mounting of any conveinent description in the frame structure 20.

The power-transfer mechanism shown in FIG. 3 includes the driving gear 30 and the intermediate member 50. This member may be considered to include the annular cap 51, which completes an embracing relationship of the intermediate member about the driven member 52. At this end of the rollers, the intermediate member 52 and the end plug 48 are preferably integral. The intermediate member 50 is of a cup-shaped configuration providing the annular rim 53 and the disc-shaped panel 54 generally perpendicular to the axis of rotation of the assembly. The shaft 49 is non-rotatable with respect to the l frame structure, by virtue of the reception of the squared end 55 in a similarly-shaped opening in the frame 2 0.

An actuating lever 56 is pivotally mounted on the portion 54 of the intermediate member 50 with the fulcrum pin 57. An offset portion 58 of the actuating lever 56 extends through the opening 59 in the intermediate member 50 for engagement with a detent device mounted within a recess 61 in the driving gear 30. The detent device appears most clearly in FIGS. 4 and 5, and is essentially a leaf spring 62 fixed at one end to the outer face of the gear 30 with the pin 63. The opposite end of the spring 62 is provided with a portion 64 engageable with the end 58 of the actuating lever 56. The shape of the portion 64 and the portion 58 of the actuating lever 56 is such that a driving relationship can only exist when the portion 64 is moving to the left with respect to the portion 58, as shown in FIG. 4. Under conditions in which the lever portion 58 encounters the portion 64 of the detent mechanism from the opposite direction, the leaf spring 50 will 4 deflect sufliciently to permit the lever portion 58 to pass underneath the portion 64.

When torque is applied through counterclockwise rotation of the gear 30, as shown in FIG. 4, the force applied to the portion 58 by the detent portion 64 will induce a limited rotation of the actuating lever 56 about the pin 57 against the restraint of the spring 65. This Spring extends to a suitable terminal connection 66 on the portion 54 of the intermediate member 50, and tends to rotate the actuating member 56 toward a retracted position in which the end 67 to a point sufficiently radially inward of the projections 68-71 on the intermediate member 52 to clear them. The application of driving torque, however, displaces the lever 56- about the pin 57 to the point that the end 67 assumes a radially outward position where it is capable of intercepting any one of the projections 68-71. The engagement of the end 56:: of the lever 56 within the pin 56b establishes a limitation to the degree of rotation of the lever 56, or any other stop arrangement can be provided to establish this limitation. Once the limitation to the rotation of the lever 56 has been attained, it forms a rotative interlock between the intermediate member 50 and the driven member 52. When no torque is applied between the gear 30 and the intermediate member 50, this condition cannot exist, by virtue of the presence of the spring continually urging the actuating lever 56 to inactive position determined by the pin 560.

It is desirable to establish a minimum degree of resistance to relative rotation between the intermediate member 50 and the driven member 52, and this resistance must be sufiicient to assure that driving torque applied by the gear 30 will move the actuating lever 56, rather than merely spin the intermediate member 50 out of driving relationship to the driven member 52. This resistance is established by the breaking action generated by the bearing ball 72 received within the radial recess 73 in the intermediate member 52. The spring 74 continually urges the bearing ball outward against the rim 53 of the intermediate member, and establishes the desired resistance to relative rotation between these components. Once the driving torque has been established, however, the forces involved are sufficiently large that it is prefarable that the projections 68-71 be in the form of inserts of relatively strong material inlaid into the intermediate member 52, and held there by set screws as indicated at 75-78.

The breaking action provided by the bearing ball 72 has the additional value of providing a predetermined degree of tension in the fabric carried by the

rolls

21 and 22. By securing the intermediate member 50 against backrotation with respect to the shaft 49, the bearing member 52 will establish the necessary drag on the rollers to establish the tension in the sign fabric. This locking against back-rotation is provided by the latch assembly shown in FIG. 8. The shaft 49 has a transverse bore 79 receiving the moving latch member 80', which is engageable with the notch 80:: in the intermediate member 50'. A spring 81 biases the latch member to the left, as shown in FIG. 8, with the end of the recess 79 being blocked by a portion 82, which can be either machined as a part of the transverse bore 79, or staked over as a secondary operation. A retaining screw 83 permits the assembly of the components, and operates as a seat for the spring 81.

The particular embodiments of the present invention which have been illustrated and discussed herein are for illustrative purposes only and are not ot be considered as a limitation upon the scope of the appended claims. In these claims, it is my intent to claim the entire invention disclosed herein, except as I am limited by the prior art.

What is claimed is:

1. A directional drive mechanism having coaxial rotary driving and driver members, wherein the improvement comprises:

an intermediate member rotatably mounted coaxially with said driving and driven members;

at least one abutment on said driven member;

an actuator mounted on said intermediate member for movement between an active position engageable with said abutment on relative rotation between said driven and intermediate members, and an inactive position clearing said abutment;

a detent mounted on said driving member and engageable with a portion of said actuator and adapted to apply force thereto exclusively in a direction to urge the same to active position; and

resistance-generating means interengaging said intermediate and driven members and adapted to inhibit relative rotation thereof.

2. A mechanism as defined in claim 1, wherein said driving, intermediate, and driven members are coaxially mounted on a fixed shaft, and said mechanism also ineludes a directional lock limiting rotation of said intermediate member to the driving direction of said driving member.

3. A mechanism as defined in claim 1, wherein said actuator is a lever pivotally mounted at an intermediate point thereon on an axis parallel to the axis of rotation of said members, one end of said lever being engageable with said abutment, and the other end engageable with said detent.

4. A mechanism as defined in claim 3, wherein said intermediate member has a face perpendicular to the axis thereof, said face having an opening, and said actuator has a portion traversing said opening for engagement with said detent,

5. A mechanism as defined in claim 1, additionally including biasing means urging said actuator to inactive position, and wherein said resistance-generating means produces a torque (opposing relative rotation between said intermediate and driven members) in excess of the torque produced by the force required to move said actuator to active position against said biasing means.

6. A mechanism as defined in claim 5, wherein said intermediate member has a cup-shaped configuration having a rim and a portion transverse to the axis thereof, said driven member abutment extending axially in the space defined by said rim.

7. A mechanism as defined in claim 6, wherein said resistance-generating means includes a bearing member mounted in said driven member for substantially radial movement, and also includes biasing means urging said bearing member against said rim.

8. A mechanism as defined in claim 7, wherein said intermediate member embraces said driven member.

References Cited UNITED STATES PATENTS 2,896,873 7/1959 Mageoch 24267.4 2,906,184 9/1959 Hennig et a1. 74-405 X 3,073,542 1/1963 Kaashoek 242-675 LEONARD H. GERIN, Primary Examiner US. Cl. XR, l92--41; 242--67.5