US3309933A

US3309933A - Cam shaft drive assembly

Info

Publication number: US3309933A
Application number: US382109A
Authority: US
Inventors: Pastor Sheldon Lee; Rudolph A Rom; Zarr Myron
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1961-05-08
Filing date: 1964-07-13
Publication date: 1967-03-21
Anticipated expiration: 1984-03-21

Description

United States Patent iitice 333,933 Patented Mar. 21, 1967 3,309,933 CAM SHAFT DRIVE ASSEMBLY Sheldon Lee Pastor, St. Paul, Minn., and Rudolph A.

Rom, Naperville, .and Ivyron Zarr, Chicago, lil., assignors to Minnesota ll/Iining and Manufacturing Company, St. Paul, Minn., a corporation of Beiaware Original application lviay 8, 1961, Ser. No. 163,352, now Patent No. 3,149,797, dated Sept. 22, 1964. Divided and this application .'Iuiy 13, 1964, Ser. No. 332,199

Claims. (Cl. 74-125) rThis application is a division of application Ser. No. 108,352, filed May S, 1961, now Patent No. 3,149,797, for Self-Hireading Magnetic Tape Recording and Reproducing Apparatus.

This invention relates to improvements in sequential driving mechanisms and in one aspect relates to a sequential drive mechanism for a cam shaft to effect rotation thereof at prescribed intervals through successive rotational steps each being less than one complete revolution.

The present invention provides an improved driving and control mechanism for edecting the sequential operation of numerous elements including a single cam shaft having numerous cams thereon engaging cooperating cam Ifollowers.

The present invention is adapted for use with an improved recorder-reproduced as described in the above referred to application and provides an improved driving and timing mechanism for effecting the operational sequences in the proper timed relationship.

The advantages of the present invention will become more apparent as the detailed description proceeds, reference being had to the accompanying drawing which forms a part of this specification, wherein:

FIGURE 1 is a side elevation View of the drive mechanism and cam shaft;

FIGURE 2 is a fragmentary sectional plan view taken approximately along the line II-II of FIGURE 1; and

FIGURES 3 and 4 are plan views illustrating certain cam profiles.

The drive mechanism of the present invention is adapted to drive a cam shaft 222 which is supported -by suitable bearings 4 and 5 fixed in an upper deck or frame member 2 and a lower deck or frame member 3, respectively. Power for operation of the mechanism is derived from an electric motor 8, illustrated in FIGURE 2, which is supported by the lower deck 3 and which has an upstanding drive shaft 10. A drive roller 11 is secured to the shaft 1G and drivingly engages a suitably mounted idler drive wheel 17 which in turn affords continuous driving engagement between the motor drive shaft 1G and a liywheel 14. 'Ihe liywheel 14 is fixed on a drive shaft or cam shaft 13 which is suitably journalled in the decks 2 and 3. The drive shaft 13 is the driving member for the novel cam shaft drive mechanism and is formed with a knurled portion 15 above the deck 3 yand below the flywheel 24.

In an apparatus where itis desirous to perform various operative steps or work functions through the use of levers in a timed or sequential relationship, such may be accomplished by means of cams having various profiles. In the illustrated embodiment of the present invention several cams 219, 22), 221, 224 and 225 yare provided upon the cam shaft 222. These cams serve to produce Jork functions through cooperating cam follower rollers such as

rollers

125 and 161, illustrated in FIGURES 1, 3 and 4. The

cam follower rollers

125 and 161 are supported by suitable levers 124 and 160 which may in turn be pivoted on the upper deck 2 and which have suitable means on the opposite end portions thereof for performing the desired work function. Similar cam followers may engage the

cams

221, 224 and 225 but are not shown.

It is to be understood however that additional cams as desired may be included `on the shaft 222.

In the illustrated embodiment the cam shaft 222 is rotated clockwise in steps or increments of 36, which increments are numbered from 1 to 10 in FIGURES 3 and 4. The actuating means for the shaft 222 comprises a one-way ratchet dog clutch below the deck 3 having a lower member 226 fixed to the cam shaft 222 and having upwardly facing inclined teeth as thus shown in FIG- URE 1. The upper clutch member 227 complemental to the lower member 226 oats on the cam shaft 222 and is provided with an integral arm 228 which carries an upstanding pin 229 which projects upward through a suitable slot in the deck 3. A ratchet Wheel 230 is xed on the cam shaft 222 Ibelow the cam 223, and a pawl 231 pivoted at 232 and biased in a clockwise direction 4by a spring 233 into engagement with the lratchet 230 prevents counterclockwise rotation of said ratchet wheel, the shaft 222 and the cams fixed thereto.

Fixed on the cam shaft 222 between the decks 2 and 3 is an indexing cam 234. Overlying the deck 3 is a generally T-shaped lever `arm 235 mounted for horizontal swinging movement about a pivot 236. The member 235 is formed with a slot 237 for accommodating the upstanding ratchet arm pin 229, said member also carrying an opstanding stub shaft 238. Freely rotatable on the stub shaft 238 is an eccentric circular cam 239 which is formed 4with a peripheral groove to accommodate a rubber-like O ring or tire member 240. A tension spring 241 is suitably anchored at one end and has its other end attached to the member 235 to bias the latter in a clockwise direction and thereby bias the cam 239 into engagement with the knurled portion 15 (FIGURE 2) of the drive shaft 13.

Referring again to FIGURES 1 and 2, a lever 242 has' a channel-shaped end portion 243 and is pivotally mounted on a fixed pin 244. The other end of the lever 242 carries an upstanding pin 245. A generally V-shaped link 246 is formed with a slot 247 adjacent its apex for accommodating the pin 24,5. One arm of the link 246 is pivotally connected to the member 235 as by pin 248, and the other arm of said link carries an upstanding cylindrical cam follower 249. A tension spring 250 connects the member 235 and link 246 as shown in FIGURE 2. Suitably mounted on the deck 3 is the solenoid 251 having a plunger 252 engageable with the vertical wall of the channel-shaped portion 243 of lever 242, said solenoid being effective when energized to project the plunger 252 from its retracted position wherein the end portion thereof engages the lever portion 243 at the dot and dash line position of the lever shown in FIG-URE 2 to the projected position of said plunger shown in FIGURE 2.

The indexing cam 2312. is of circular configuration, See FIGURE 2, except for cut-away peripheral portions 253 and 254, and the cam follower 249 is adapted to coact with said cam. The clockwise rotation of the drive shaft 13 causes counterclockwise rotation of the cam 239 held in Contact therewith by the spring 241, and such rotation of the cam 239 causes oscillation or swinging movement of the member 235 between the solid line and the dot and dash line positions thereof shown in FIGURE 2. Such oscillatory movement continues -so long as the cam 239 remains in driving engagement with the drive shaft 13. Movement of the member 235 toward its dot and dash line position causes movement of the ratchet arm pin 229 therewith and clockwise rotation of the upper ratchet member 227 through an angle of 36 to effect like rotation of the cam shaft 222 and all of the cams fixed thereto. Return movement of the member 235 toward its solid line position returns the upper ratchet member 227 to its initial position for reengagement of its teeth with those of the lower ratchet member 226.

Movement of the member 235 toward its dot and dash line retracted position pulls the cam follower 249 on link 246 into engagement with the periphery of the indexing cam 234, and if neither of the cut-out portions 253 and 254 is presented to said follower, the oscillation of the member 235 continues. If, however, a cutout portion 253 or 254 is presented to the follower 249 when the member 235 approaches the dot and dash line position thereof, said follower moves into the presented cut-out portion to the dot .and dash line position shown in FIGURE 2. Such movement of the follower 249 permits the pin 245 to move to over-center position with respect to a line connecting the

pins

244 and 248, and the toggle provided by the link 246 and lever 242 is held in the over-center dot and dash line position shown in FIGURE 2 by the bias of the springs 241 and 25@ forming holding means for the member 235 when in its retracted position. With the toggle in over-center position the member 235 is prevented from returning from its dot and dash line position, and the cam roller 24) rotates out of engagement with the drive shaft 13. The parts of the actuating mechanism for cam shaft 222 remain stationary until the solenoid 251 is subsequently energized to project the plunger 252 against the wall of the portion 243 of the lever 242 and pivot said lever counterclockvvise from its dot and dash line position sufficiently to return the pin 245 over-center. This breaks the toggle and permits the spring 241 to again pull the cam roller 239 into driving engagement with the drive shaft 13 to thereupon initiate another cycle of oscillation.

It is to be understood that the cut-away portions 253 and 254 may have varying shapes or the indexing cam 234 may include additional cut-away portions to interrupt the timed rotation of the cam shaft 222 at intervals as desired. Control of the incremental drive for cam 'shaft 222 is thus provided by the indexing cam 234, the solenoid 251 and plunger 252.

Energization of the solenoid 251 will be in response to tbe closing of one or more switches, not shown, included in the apparatus to which the illustrated drive mechanism forms a part.

Having thus described one specific embodiment of the invention it is to be understood that various changes and vmodifications may be made therein without departing from the spirit of the invention, and all such changes are contemplated as may come within the scope of the appended claims.

What is claimed is:

1. In combination, a drive shaft, an arm mounted for pivotal movement on an axis parallel with that of said drive shaft, an eccentric circular cam mounted on said `arm for rotation on an axis parallel with that of said drive shaft,` means biasing said cam toward engagement with said drive shaft, rotation of said drive shaft while said cam is engaged therewith effecting rotation of said cam and oscillatory movement of said arm, a cam shaft, a driving connection for effecting rotation of said cam shaft in response to oscillatory movement of said arm, said driving connection comprising a single direction clutch having an oscillatable first member connected to said arm, and va cooperating second member fixed to said cam shaft, releasable holding means associated with said arm for holding the latter substantially in its retracted position farthest from said drive shaft when moved to said retracted position, and control means including an indexing cam carried by said cam shaft for engagement by said holding means for rendering said holding means operative or inoperative to hold the arm retracted when said cam shaft reaches preselected positions.

2. In combination, Ia drive shaft, an arm mounted for pivotal movement on an axis parallel with that of said drive shaft, an eccentric circular cam mounted on said arm for rotation on an axis parallel with that of said drive shaft, means biasing said cam toward engagement with said drive shaft, rotation of said drive shaft while said cam is engaged therewith effecting rotation of said cam and oscillatory movement of said arm, a cam shaft, a driving connection for effecting rotation of said cam shaft in response to oscillatory movement of said arm, said driving connection comprising a single direction clutch having an oscillatable first member connected to said arm, and a cooperating second member fixed to said cam shaft, releasable holding means `associated with said arm for holding the latter substantially in its retracted position farthest from said drive shaft when moved to said retracted position, control means including `an indexing cam mounted on said cam shaft for engagement with said holding means, said indexing cam having at least one first position in which said control means renders said holding means inoperative 'and at least on-e second position in which said control means permits said holding means to operate, and means for releasing said holding means while said indexing cam is in its second position and said holding means is holding said arm in retracted position.

3. In combination, a drive shaft, an arm mounted for pivotal movement on an axis parallel with that of said drive shaft, an eccentric circular cam mounted on said arm for rotation on an axis parallel with that of said drive shaft, means biasing said cam toward engagement with said drive shaft, rotation of said drive shaft while said cam is engaged therewith effecting rotation of said cam and oscillatory movement of said arm, a cam shaft, a driving connection -ffor effecting rotation of said cam shaft in response to oscillatory movement of said arm, said driving connection comprising a single direction clutch having an oscillatable first member connected to said arm, and a cooperating second member fixed to said cam shaft, releasable holding means comprising a toggle linkage associated with said arm and normally movable to an over-center holding position on movement of said arm substantially to its retracted position farthest from said drive shaft, and control means including an indexing cam adapted for engagement with said toggle linkage, said indexing cam having at least one first position in which said control means prevents movement of said linkage to said over-center holding position, said indexing cam also having at least one second position in which said control means permits movement of said linkage to said over-center holding position wherein it holds said arm in substantially said retracted position.

4. In combination, a drive shaft, an arm mounted for pivotal movement on an axis parallel with that of said drive shaft, an eccentric circular cam mounted on said arm for rotation on an axis parallel with that of said drive shaft, means biasing said cam toward engagement with said drive shaft, rotation of said drive shaft while said cam is engaged therewith effecting rotation of said cam and oscillatory movement of said arm, a cam shaft, a driving connection for effecting rotation of said cam shaft in response to oscillatory movement of said arm, said driving connection comprising a single direction clutch having an oscillatable first member connected to said arm, and a cooperating second member fixed to said cam shaft, releasable holding means comprising a toggle linkage associated with said arm and normally movable to an over-center holding position on movement of said arm substantially to its retracted position farthest from said drive shaft, control means including an indexing cam carried by said cam shaft for engagement with a yfollower on said toggle linkage, said indexing cam having at least one first position in which said control means prevents movement of said linkage to said over-center holding position, said indexing -cam also having at least one second position in which said control means permits movement of said linkage to said overcenter holding position wherein it holds said arm in substantially said retracted position, and electroresponsive actuating means adapted for engagement with said toggle linkage for effecting return movement of said toggle linkage when it is in its over-center position, thereby releasing said arm for advancing movement toward said drive shaft.

S. In combination, a drive shaft, an arm mounted -for pivotal movement on an axis parallel with that of said drive shaft, an eccentric circular rcam mounted on said arm for rotation on an axis parallel with that of said drive shaft, means biasing said cam toward engagement with said drive shaft, rotation of said drive sha-ft while said cam is engaged therewith effecting rotation of said cam and oscillatory movement of said arm, a cam shaft, a driving connection for eifecting rotation of said cam shaft in response to oscillatory movement of said arm, said driving connection comprising a single direction clutch having an oscillatable first member connected to said arm, and a cooperating second member fixed to said cam shaft, releasable holding means comprising a toggle linkage associated with said arm and normally movable to an over-center holding position on movement of said arm substantially to its retracted position lfarthest from said drive shaft, control means including an indexing cam driven by said cam shaft and positioned for engagement with said toggle linkage, said indexing cam having at least one rst position in which said control means prevents movement of said linkage to said over-center holding position, said cam also having at least one second position in which said control means permits movement of said linkage to said over-center holding position wherein it holds said arm in substantially said retracted position, and electroresponsive actuating means adapted for engagement with said toggle linkage for eifecting return movement of said toggle linkage when it is in its over-center position, thereby releasing said arm for advancing movement toward said drive shaft.

References Cited by the Examiner UNITED STATES PATENTS 1,155,459 10/1915 Woodward 74-125 1,565,601 12/1925 Swanson 74-124 1,568,430 1/1926 Uhl 74-25 1,758,730 5/1930 Winters 74-45 2,128,413 8/1938 Hejduk et al. 74-124 X MILTON KAUFMAN, Primary Examiner.

FRED C. MATTERN, Examiner.

D. H. THIEL, Assistant Examiner.

Claims

1. IN COMBINATION, A DRIVE SHAFT, AN ARM MOUNTED FOR PIVOTAL MOVEMENT ON AN AXIS PARALLEL WITH THAT OF SAID DRIVE SHAFT, AN ECCENTRIC CIRCULAR CAM MOUNTED ON SAID ARM FOR ROTATION ON AN AXIS PARALLEL WITH THAT OF SAID DRIVE SHAFT, MEANS BIASING SAID CAM TOWARD ENGAGEMENT WITH SAID DRIVE SHAFT, ROTATION OF SAID DRIVE SHAFT WHILE SAID CAM IS ENGAGED THEREWITH EFFECTING ROTATION OF SAID CAM AND OSCILLATORY MOVEMENT OF SAID ARM, A CAM SHAFT, A DRIVING CONNECTION FOR EFFECTING ROTATION OF SAID CAM SHAFT IN RESPONSE TO OSCILLATORY MOVEMENT OF SAID ARM, SAID DRIVING CONNECTION COMPRISING A SINGLE DIRECTION CLUTCH HAVING AN OSCILLATABLE FIRST MEMBER CONNECTED TO SAID ARM, AND A COOPERATING SECOND MEMBER FIXED TO SAID CAM SHAFT, RELEASABLE HOLDING MEANS ASSOCIATED WITH SAID ARM FOR HOLDING THE LATTER SUBSTANTIALLY IN ITS RETRACTED POSITION FARTHEST FROM SAID DRIVE SHAFT WHEN MOVED TO SAID RETRACTED POSITION , AND CONTROL MEANS INCLUDING AN INDEXING CAM CARRIED BY SAID CAM SHAFT FOR ENGAGEMENT BY SAID HOLDING MEANS FOR RENDERING SAID HOLDING MEANS OPERATIVE OR INOPERATIVE TO HOLD THE ARM RETRACTED WHEN SAID CAM SHAFT REACHES PRESELECTED POSITIONS.