US3148558A

US3148558A - Adjustable actuating mechanism

Info

Publication number: US3148558A
Application number: US251392A
Authority: US
Inventors: Donald R Stevens
Original assignee: Bendix Corp
Current assignee: Bendix Corp
Priority date: 1963-01-14
Filing date: 1963-01-14
Publication date: 1964-09-15
Anticipated expiration: 1981-09-15

Description

Sept. 15, 1964 D. R. STEVENS ADJUSTABLE ACTUATING MECHANISM Filed Jan. 14, 1965 2 Sheets-Sheet 2 FIG.3

United States Patent Office 3,148,558 Patented Sept. 15, 1964 3,143,558 ADEUSTABLE ACTUATING MECHANISM Donald R. Stevens, North Hollywood, Calif., assignor to The Bendix Corporation, North I-Iloilywood, Calif., a corporation of Delaware Filed Jan. 14, 1963, Ser. No. 251,392 6 Claims. (Cl. 74395) This invention relates to control devices actuated by rotating mechanisms for performing an operation (such as stopping the mechanism) after rotation thereof into a predetermined position or positions. It is particularly useful in applications involving movement of an element through a large number of revolutions.

An object of the invention is to provide a relatively simple and compact mechanism that is accurately responsive to movement of a rotary element through a predetermined large number of revolutions.

Another object is to provide a relatively simple and compact mechanism that is accurately responsive to move ment of a rotary element in either direction between two limit positions.

Another object is to provide a device of the type referred to in which each limit position can be accurately adjusted between wide limits.

Other more specific objects and features of the invention will appear from the following description with reference to the drawings, in which:

FIG. 1 is a schematic diagram showing one type of system to which the invention is applicable.

FIG. 2 is a cross-sectional view of the invention.

FIG. 3 is an exploded view showing one-half of the structure of FIG. 2.

FIG. 1 shows application of the invention to the control of a screw jack intended to be moved between predetermined lower and upper positions. The jack comprises a screw vertically slidably supported in a stationary base 11. The screw 10 is prevented from rotating by a pin 12 extending therethrough and into diametrically opposite slots 13 in the passage 14 in the base 11 in which the screw slides. Movement of the screw 10 up and down is effected by rotation of a nut 15 which engages the threads of the screw 10 and sets upon the base 11. The nut 15 carries a gear 16 which is engaged by a pinion 17 on the shaft of an electric motor 18 which can be driven in either direction, as by selectively energizing it with current of either positive or negative polarity. The nut 15 also carries a small gear or pinion 19 which is coupled to an input gear 20 (as by an idler gear 19a) of a device 21 in accordance with the invention.

The function of the device 21 is to open a switch 22 in response to rotation of the nut 15 sufficient to raise the screw 10 into a predetermined upper limit position, and to open a switch 23 in response to rotation of the nut 15 in the opposite direction a sufiicient number of turns to lower the screw 10 into a desired limit position. Thus, if it is assumed that energization of the motor 18 with current of positive polarity rotates it in direction to raise the screw 19, raising movement may be instigated by closing a switch 24 to connect a source of positive current through the switch 22 and a common lead 25 to the motor 18. When the motor reaches its upper limit position, the switch 22 opens, automatically stopping 1H; motor and the screw. If the switch 24 is therefore opened and the switch 26 is closed, a current of negative polarity is applied through the limit switch 23 and the conductor 25 to the motor 18, operating it in the reverse direction to move the screw 10, into its lower position, and when the nut 15 has been rotated the necessary number of turns to accomplish this result, the switch 23 is opened, thereby stopping the motor with the jack in its lower limit position.

The mechanism 21 will now be described with reference to FIGS. 2 and 3.

The gear 20, previously referred to, is rotatably supported on a shaft 311 which is supported in

opposite end walls

31 and 32 of a casing 33. Secured to the gear 20 on opposite sides thereof are two similar pinions one of which, 34, appears in FIG. 2 and FIG. 3.

Associated with the pinion 34 are three planet gears 35 each rotatable on a stub shaft 36 projecting from a planet carrier 37 consisting essentially of a disk, the peripheral surface of which acts as a cam having a short lower portion 38 breaking an otherwise continuous high portion 39. The planet gears 35 also engage an internal gear 40 and provide the radial support for the internal gear 40. The outer periphery of the gear 40 has worm wheel teeth 41 which are engaged by a worm 42 which normally restrains the ring gear 41 against rotation but enables rotational adjustment thereof by the rotation of a knurled knob 43 on one end of the worm. It will be apparent that in response to rotation of the sun gear 34 the planet gears 35 are rotated about the shafts 36 and the gears are also revolved within the internal gear 49, thereby rotating the planet carrier 37.

Attached to the planet carrier 37 for rotation therewith on the shaft 34 is a small gear 45 which meshes with a set of three gears 46 which are independently supported on three stationary stub shafts 47 extending from the end wall 31 of the casing and symmetrically disposed about the shaft 30. The gears 46 also mesh with an internal gear 48 which is radially supported by the gears 46 and rotated by the latter in response to rotation of the gear 45. The internal gear 48 carries on its outer surface a cam surface generally similar to that on the planet carrier 37 and consisting of a long high surface 49 and a short low surface 50. It will be apparent that since the gears 46 are fixed against revolution they act simply as idler gears between the central gear 45 and the internal gear 48 and cause the latter to rotate in direction opposite to the rotation of the gear 45.

It will be observed from FIG. 1 that the pinion 19 drives the larger input gear 20 at a reduced speed, and the sun gear 34 drives the planet carrier 37 at a still further reduced speed. The central gear 45 in turn drives the second internal gear 48 at a further reduced speed. It will also be observed that the planet carrier 37 and the internal gear 48 are positioned side by side, and their exterior surfaces cam contacts a common cam follower 52 which consists of a lever 53, the free end 54 of which bears against the plunger 55 of a microswitch 56 containing the switch contacts 22 of FIG. 1. These switch contacts are closed when the lever 53 depresses the plunger 55, as when the follower 52 is riding on the high cam surface of one or the other of the

elements

37 and 43. However, when the

low points

38 and 50, respectively, of the two cam surfaces are juxtaposed to the follower 52 the latter cam move to permit elevation of the switch plunger 55 (by spring within the switch 56) and open the switch, thereby stopping the mechanism. During each cycle of operation the fast moving planet carrier 37 may rotate many times, but the slow moving internal gear 48 rotates through less than one revolution. The cam on the slow-moving gear 48 is therefore capable of measuring a time of long duration, but this long time is then accurately terminated by the faster movement of the cam on the planet carrier 37.

In a typical application, the input pinion 19 may have 16 teeth and the input gear 25 may have teeth, thereby causing the gear 211 to make 80 revolutions while the pinion 19 is making 400 revolutions. If the pinion 34 is provided with 9 teeth and the internal gear 40 is provided with 81 teeth, the planet carrier 37 bearing the

cam surfaces

37 and 38 will then make 3 revolutions in response to 400 revolutions of the pinion 19. The central pinion 45, the gears 46 and the internal gear 43 have the same number of teeth as the sun gear 34, planet gears 35 and ring gear dtt, which provides a 9 to 1 reduction so that during '8 revolutions of the cam supporting member 37 the cam supporting member 48 moves through 320.

The two low cam portions 38 and 5t) will therefore for the first time jointly align themselves with the cam follower '52. at the time when the fast cam has moved through 8 complete revolutions and the slow cam has moved through 320.

There has been described in detail, with reference primarily to FIG. 3, only one-half of the mechanism, both halves of which are shown in FIG. 2. Since both halves are identical, no further description will be given of the second half.

Although for the purpose of explaining the invention a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and I do not desire to be limited to the exact details shown and described.

, Iclaim:

1. Motion responsive apparatus operable in response to rotation of an input element into a predetermined position comprising:

a first epicyclic gear mechanism comprising a sun gear constituting said input element;

an internalgear coaxial with said sun gear;

a planet gear intercoupling said sun and internal gears;

a rotatable planet carrier coaxial with said sun and internal gears and axially offset from said sun, planet and internal gears;

a second gear mechanism coaxial with said first mechanism and comprising a central gear connected to, and driven by, said planet carrier;

a second internal gear longitudinally adjacent said carrier;

an idler gear intercoupling said central and internal gears;

a second stationary carrier rotatably supporting said idler gear whereby said second internal gear is rotated at a lesser speed in response to rotation of said central gear; 7

means normally restraining said first internal gear from rotation whereby rotation of said sun gear rotates said planet carrier at a lesser speed;

said planet carrier and said second internal gear having external cam surfaces thereon and a common cam follower for both said cam surfaces;

said cam surfaces each having a long section of one radius capable of maintaining said follower in a first position and each having a second section of different radius permitting said follower to move into a second position only when both of said second sections pass said follower simultaneously.

2. Apparatus in accordance with claim 1 in which said means for normally restraining said first internal gear from rotation includes means for adjustably rotating the gear to advance or retard said planet carrier and said second internal gear independently of said input element.

3. Apparatus according to claim 2 in which said adjustable restraining means comprises a worm wheel on the exterior surface of said first internal gear and a worm engaging said worm gear.

4. Apparatus according to claim 1 including a central shaft in the axis of said sun and internal gears for rotatably supporting said sun gear and planet carrier;

said planet carrier having in addition to said first planet gear at least two additional planet gears symmetrically angularly disposed with said first planetary gear about said axis whereby said first internal gear is radially supported by said carrier and planet gears with respect to said shaft. 5. Apparatus according to claim 1 including a casing having an end wall adjacent said second gear mechanism on the side thereof remote from said first gear mechanism, at least two additional idler gears symmertically angularly disposed with said first mentioned idler gear about the axis of said central and ring gears, each idler gear having a rotatably supporting stub shaft extending from and fixedly supported by said end wall, said second internal gear being radially supported for rotation about its axis by the three idler gears associated therewith.

'6. Apparatus according to claim 1 responsive to rotation of said input element into either of two opposite limit positions comprising:

third and fourth gear mechanisms identical with said first and second gear mechanisms, respectively, and coaxial and adjacent thereto, said third gear mechanism having its sun gear secured to said first sun gear for rotation therewith;

' and a second cam follower corresponding to said first cam follower actuated by the external cam surfaces of said third and fourth mechanisms;

saidthird and fourth mechanisms being so phased relative to said first and second mechanisms as to actuate the second cam follower into its second position in a second position of said input elements spaced from said first mentioned predetermined position.

References Qited in the file of this patent UNTTED STATES PATENTS 2,673,313 Bennett Mar. 23, 1954 FOREIGN PATENTS 647,863 Great Britain Dec. 20, 1950 672,713 Great Britain May 28, 1952

Claims

1. MOTION RESPONSIVE APPARATUS OPERABLE IN RESPONSE TO ROTATION OF AN INPUT ELEMENT INTO A PREDETERMINED POSITON COMPRISING: A FIRST EPICYCLIC GEAR MECHANISM COMPRISING A SUN GEAR CONSTITUTING SAID INPUT ELEMENT; AN INTERNAL GEAR COAXIAL WITH SAID SUN GEAR; A PLANET GEAR INTERCOUPLING SAID SUN AND INTERNAL GEARS; A ROTATABLE PLANET CARRIER COAXIAL WITH SAID SUN AND INTERNAL GEARS AND AXIALLY OFFSET FROM SAID SUN, PLANET AND INTERNAL GEARS; A SECOND GEAR MECHANISM COAXIAL WITH SAID FIRST MECHANISM AND COMPRISING A CENTRAL GEAR CONNECTED TO, AND DRIVEN BY, SAID PLANET CARRIER; A SECOND INTERNAL GEAR LONGITUDINALLY ADJACENT SAID CARRIER; AN IDLER GEAR INTERCOUPLING SAID CENTRAL AND INTERNAL GEARS; A SECOND STATIONARY CARRIER ROTATABLY SUPPORTING SAID IDLER GEAR WHEREBY SAID SECOND INTERNAL GEAR IS ROTATED AT A LESSER SPEED IN RESPONSE TO ROTATION OF SAID CENTRAL GEAR; MEANS NORMALLY RESTRAINING SAID FIRST INTERNAL GEAR FROM ROTATION WHEREBY ROTATION OF SAID SUN GEAR ROTATES SAID PLANET CARRIER AT A LESSER SPEED; SAID PLANET CARRIER AND SAID SECOND INTERNAL GEAR HAVING EXTERNAL CAM SURFACES THEREON AND A COMMON CAM FOLLOWER FOR BOTH SAID CAM SURFACES; SAID CAM SURFACES EACH HAVING A LONG SECTION OF ONE RADIUS CAPABLE OF MAINTAINING SAID FOLLOWER IN A FIRST POSITION AND EACH HAVING A SECOND SECTION OF DIFFERENT RADIUS PERMITTING SAID FOLLOWER TO MOVE INTO A SECOND POSITION ONLY WHEN BOTH OF SAID SECOND SECTIONS PASS SAID FOLLOWER SIMULTANEOUSLY.