US2909933A

US2909933A - Dial system with limit and lock for multiturn shafts

Info

Publication number: US2909933A
Application number: US628143A
Authority: US
Inventors: Leo R Kalous
Original assignee: Collins Radio Co
Current assignee: Collins Radio Co
Priority date: 1956-12-13
Filing date: 1956-12-13
Publication date: 1959-10-27
Anticipated expiration: 1976-10-27

Description

Oct. 27, 1959 R. KALOUS 2,909,933

DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURN SHAFTS Filed Dec. 13, 1956 2 Sheets-Sheet 1 INVENTOR. 1.50 R. KnLous Arronmsvs Oc 27, 1 5 L. R. KALOUS 2,909,933

DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURN SHAF'TS Filed Dec. 13, 1956 2 Sheets-Sheet 2 IOJ INVENTOR. Lso R KALous wwi Mu.

United States Patent G DIAL SYSTEM WITH LIMIT AND LOCK FOR MULTITURN SHAFTS Leo R. Kalous, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Application December 13, 1956, Serial No. 628,143

3 Claims. (Cl. 74-102) This invention relates to dial systems and more particularly to end-stop systems adaptable to rotating multiturn loads.

In prior art dial systems the usual practice has been to put limit stops on the load rotated, such as a multiturn inductor, capacitor, or resistor. The knob at the front panel is then geared down so that the accompanying dial is moved in a fashion consistent with the input. As a consequence of the gearing, however, the stops have an elastic feel at the knob as a result of a disadvantageously high gear ratio. Careless handling results in breakage at the stops or damage to the gear train. A similar difficulty arises in position locks when the load itself is locked in place by a panel-actuated knob.

Accordingly, it is an object of the invention to provide both direct-acting limit stops and a lock for a multiturn load, the load turns being related to the dial by a gear It is a further object of .the invention. to provide a limit stop system which is crisp and certain in its feel at the front panel knob.

It is a further object of this invention to provide a multiturn load single-turn dial system which is relatively simple and easy to manufacture, yet which is reasonably foolproof in use.

- It is 'a feature of the invention that an epicyclic gear train is utilized to make available to the designer a wide range of gear ratios of which one can be selected for the particular task, e.g., between ten and one hundred, providing for a directly-driven multiturn load with only a single turn dial.

It is a further feature of this invention that the system lends itself to disassembly from the front panel.

Further objects, features, and advantages of ,the invention will become apparent from the following description andclaims-when read in conjunction with the drawings, in 'which: p

Figure 1 shows an exploded isometric view of the invention, v

Figure 2 shows a plan view of a portion of Figure 1 including the locksystem, and s I p Figure 3 shows a side view of Figure 2 showing more clearly the lock system.

In Figure 1 a majority of the system is mounted on or adjacent to a frame 10. Parallel to saidv frame is a front panel 11 which is spaced from frame 10. The upper surface of the front panel 11 is external of the equipment. Here a dial 12 is provided having next to it a coaxial knob 13. Dial 12 has indicia on it reflecting the full extent of rotation relative to an indicator mark 14.

A shaft 16 extends through frame towards the rear of the apparatus for coupling to a multiturn loadsuch as a rotary inductor which is turned a multiplicity of full turns e.g., from thirty to one hundred times, for full inductancevariation. The front knob 13 is directly mounted on load shaft 16. Concentric to load shaft 16 is a fixed gear 17 which is mounted on frame 10. Meshing with gear 17 is a pair of epicyclic gears 18 and 4 rate.

Patented Oct. 27, 1959 19. Gear 18 meshes with fixed gear 17 and is coupled to gear 19. Gear 19 meshes with dial gear 21. The epicyclic gears are mounted on an axle 22 which is carried on gear carrier 23.

Epicyclic gears

18 and 19 are free to rotate on their axle 22. The epicyclic gear carrier 23 is mounted on load shaft 16 and fixed thereto so that it rotates with said shaft. Also mounted rigidly. to gear carrier 23 is stop wheel 24. The ratio of turns between shaft 16 and the slightly less than one turn of the dial shaft is established by the desired number of turns of the load between stops. I

Stop wheel 24 is of constant radius throughout most of its circumference except for two portions 25 which are cut inward radially to provide radial stop faces 26. As can be seen in the drawing, these radial incursions and stop faces are symmetrical with respect to rotation. Dial gear 21 is mounted on a dial shaft 27, which is hollow to permit the load shaft 16 to extend coaxially through it. Also mounted on and fixed to shaft 27 is a control disc cam 28. Cam 28 has a substantially constant radius throughout most of the circumference except in a small portion 29 where a rotationally symmetrical radial incursion occurs. The slopes of the radial incursion are smooth with a gradual rise for gentle camming action, Where the constant radius of stop wheel 24 is less than the constant radius of cam 28, such that the stop wheel incursions do not act as the stop pin lift- Dial shaft 27 is parted. by a transverse V-shaped notch 30 for detachable coupling to a separated portion 31 of the dial shaft on the front of the front panel. On the separated portion 31 is mounted the dial 12. Under knob 13, compressed between knob 13 and dial 12, is a dial spring 32 which presses shaft 31 into the V, 30. This permits a satisfactory coupling of the 'dial to the mechanism with a simplified way for disassembly of the front panel from the frame for servicing and further disassembly of the mechanism.

In operation of the load by knob 13, rotation of knob 13 rotates load shaft 16 and the load directly. This retation turns also gear carrier 23.

-As gear carrier 23 is turned,

epicyclic gears

18 and 19 are dragged around the peripheries of

gears

17 and 21. As a consequence of the gears having dissimilar numbers of teeth, gear 21 is turned at a rate different from that of carrier 23 to turn dial shaft 27 at a slow As dial gear 21 is rotated at a reduced speed, so also is dial 12 rotated by its coupling through the V notch 30. I

The rest of the stop system involves a stop plate 40 having fixed thereon a follower and stop pin 41. Stop plate 40 is mounted by means of two slots. One is a shaft slot 42 which is an elongated hole which is wide enough to clear shaft 27 and which is just long enough to permit the stop pin to move in and out of engagement with the stop faces 26 on stop wheel 24. A second slot 43 is similarly proportioned for mounting on fixed post 44 to provide the rotational rigidity necessary for the stop action. Cam follower tension spring 46 is attached between a mounting post 47 fixed to stop plate 40 and a retainer ring or washer 48 which sets into a notch 49 on hollow dial shaft 27. A washer and retainer 51 engages the end of fixed post 44 for retention of the stop plate on the fixed post.

In operation, the cam follower spring 46 pulls the stop plate 40 towards the shaft 27. This causes follower and past follower and stop pin 41, there is no interference. Between stops, the follower pin rides on the constant radius portion of the control disc 28. At the ends the more slowly moving control disc campermits the fol- 'lower.pin '41 to drop into aperture 29. Simultaneously, one of the stop faces 26 approaches and meets the stop :pin, the radial incursion 25 permitting the follower pin 41 -to move in radially, stopping rotation of load shaft 16. It is readily seen that the interference of rotation of stop wheel 24 by stop pin 41 is direct, stop plate 40 being mountedon the frame and the gear carrier 23 :nio'ving at the load speed, leaving no gear reduction be- ;tween the knob 13 and the stop pin. As a result of this arrangement, the stopping action is direct and crisp and WithOllt any intervening gear train to make the stop feel mushy. It is'a'lso apparent that rotation of knob 13 away fro the stop causes the rise of the control disc cam 28 or the incursion 25 to lift the stop pin 41 radially outward away from the stop wheel 24 dependent 'on the gear ratio,

to permitrotation away from the stop. As a consequence of the rotational symmetry of the control disc 28 for the stop wheel 24, the above-described action occurs for "either direction of rotation to the desired end limits.

-along a chord of the gear carrier 23.

The end of the clamp strap 50 is energized at 52 fo'r locking, as seen more clearly in Figure 3. Strap 50 is bent not only laterally into a broad V, but into a shallow U at '53. The bottom of this shallow U bears against gear 'carrier 23. For locking, end 52 is pushed towards frame 10 so as to drive the bottom of the shallow U 53 against the gear carrier. This conformation of the 'clamp strap 50 is such as to give it considerable resilience. This resilience makes a contact with gear carrier 23 having such a friction force as to make rotation with knob 13 very difiicult. This results in a very simple and yet very reliable load position lock.

The actuator at the end 52 of the lock strap is a threaded shaft 55 which is mounted within a triple "threaded nut 56. Thus, to lock, shaft 55 is rotated by a panel knob 57 to move inwardly against strap end 52 at a relatively fast rate. Double or quadruple threads may be used if desired but triple threads give a relatively fast rate of advance to make the lock effective within a turn of knob 57. This permits the use of a mark on the to particular embodiments thereof, it is not to be so.

limited as changes and modifications may be made therein whichare within. thefull intended scope of theinvention as defined by the appended claims.

I claim:

l. A rotational limiting system for a multiturn control shaft comprising, a bidirectional load shaft having a predetermined limit of rotation in each direction, a stop wheel fixed coaxially to said control shaft, a stop pin, means formounting'said stop-pin rigidly circumferentially with respect to said "stop 'wheel, a rotatable cam connected through an epicyclic gear system to said loa'cl shaft, means for rotating said shaft in either direction,

said cam being rotated by said epicyclic gear system in response to the rotation of said shaft at a rate-different from that of the rotation of said shaft, means responsive to the rotation of said cam over a predetermined range for moving said stop pin radially to engage a circumferential face of said stop wheel, a stop face projecting radially from said face of said stop wheel, and said predetermined limits of rotation being positively determined by the engagement of said stop face by said stop pin.

2. A rotational limiting system for a multiturn load comprising, a bidirectional load shaft having a predesaid stop wheel, means for urging said pin inwardly 'againstthe circumferential edge 'of said control disc cam,

means for rotating said load 'shaft' in either direction, the gear 'ratio of said'coaxial fixed gear to said epicyclic gear being different from the gear ratio of said epicyclic gear to said coaxial rotatable gear so that the control disc cam is rotated at a different rate from that of said stop wheel in response to rotation of said load shaft, said control disc cam having a radial incursion for permitting said pin to engage the edge of said stop wheel over a predetermined range of rotation of said control disc'cam, a stop face projecting radially from said edge of said stop wheel, and said predetermined limits of rotation being positively determined by the engagement of said stop face with said stop pin.

3. A rotation limit system as claimed in claim 2 in combination with a locking means, said locking means being operable for engaging said gear carrier to lock said load shaft in any selected position.

References Cited in the file of this patent UNITED STATES PATENTS 2,496,455 Elliot Feb. 7, 1 950 2,662,422 McGowcn Dec. 15, 1953 2,716,896 Beldt et al. Sept. 6, 19