US3626121A

US3626121A - Centrifugal actuator

Info

Publication number: US3626121A
Application number: US56792A
Authority: US
Inventors: Walter A Paulssen
Original assignee: Dresser Industries Inc
Current assignee: Lift Tech International Inc
Priority date: 1970-07-21
Filing date: 1970-07-21
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: CA934621A

Abstract

A device for mechanically actuating a control mechanism on a predetermined velocity being attained between relatively moving parts of an apparatus on which the control mechanism is operative. The device comprises an input section rotatably responsive to movement of the apparatus on which the control mechanism is supported. An output section juxtaposed to the input section is normally disengaged therefrom and operatively detains the control mechanism against actuation. In response to excessive velocity increase, a plurality of balls inwardly detained in radially extending slots of the input section are centrifugally slung outward to rotatably couple the input and output sections for the latter to release the control mechanism for its actuation.

Description

United States Patent Inventor Walter A. Paulssen Spring Lake, Mich. Appl. No. 56,792 Filed July 21, 1970 Patented Dec. 7, 1971 Assignee Dresser Industries, Inc. Dallas Tex.

CENTRIFUGAL ACTUATOR 12 Claims, 7 Drawing Figs.

U.S. Cl 200/80 Int. Cl "01h 35/10 Field of Search 200/ 80; 102/79; 73/535, 536; 317/5 Reierences Cited v UNITED STATES PATENTS 2,914,359 11/1959 Yarber 200/80 X Primary Examiner-Herman .l. l-Iohauser AttorneysRobert W. Mayer, Thomas P. Hubbard, Jr., Daniel Rubin, Raymond T. Majesko, Roy L. Van Winkle, William E. Johnson, Jr. and Eddie E. Scott ABSTRACT: A device for mechanically actuating a control mechanism on a predetermined velocity being attained between relatively moving parts of an apparatus on which the control mechanism is operative. The device comprises an input section rotatably responsive to movement of the apparatus on which the control mechanism is supported. An output section juxtaposed to the input section is normally disengaged therefrom and operatively detains the control mechanism against actuation. In response to excessive velocity increase, a plurality of balls inwardly detained in radially extending slots of the input section are centrifugally slung outward to rotatably couple the input and output sections for the latter to release the control mechanism for its actuation.

PATENTEDDEE 7:971 3.626121 SHEET 1 OF 3 INVF NTUH WALTER A. PAULSSEN FIG. I

PATENTED DEC 7 l97l SHEET 2 OF 3 FIG. 2

nivr mun WALTER A. PAULSSEN PATENTEU DEC 7 l9?! SHEET 3 BF 3 FIG. 3

FIG. 4

FIG. 5

WV! NTW WALTER A. PAULSSEN m mum r CENTRIFUGAL ACTUATOR CROSS-REFERENCE TO RELATED APPLICATIONS Application entitled "Safety Brake" cofiled herewith in the names of Walter A. Paulssen and Robert R. Johnston and incorporated herein by reference.

BACKGROUND OF THE INVENTION l. The field of art to which the invention pertains includes the art of mechanical motion-sensing devices and in particular to devices of that type capable of actuating a safety control unit such as a brake, switch, alarm or the like in response to detecting an excess linear or rotary velocity between relatively moving component parts.

2. Devices responsive to excessive velocity variations have been previously known and are common on elevating apparatus such as stacker cranes in which a runaway speed condition usually reflects failure in the lift mechanism. Exemplifying cranes of that type is the disclosure of U.S. Pat. No. 3,250,402 in which a safety brakeis operative by a physical separation between the triggering device and a brake control mechanism occasioned by relative speed differences of the components to which they are respectively secured. While these prior-type devices have given highly satisfactory perfonnance for many years, they are known to provide false signals on the side of safety and to reset themselves as a result of overcoming a signal occasioned by momentary lags from relative acceleration differences. This latter situation is particularly prevalent on vertically moving components on which slack or gravitational drift, even though slight, can cause unwanted braking action.

SUMMARY The present invention relates to an improved device for mechanically actuating or triggering a control mechanism in response to excess relative speed, between component parts. The device is increasingly speed sensitive as compared to prior art devices as to be less susceptible to false indications from acceleration lags and is particularly unaffected by physical separation caused by gravitational drift or the like. At the same time the device affords onsite adjustment to variably preset the desired velocity condition at which it is to be responsive. Notwithstanding these enhanced performance features, the device is simple in construction yet highly reliable while being capable of being accommodated on a mass majority of existing equipment.

In accordance herewith, a plurality of balls are inwardly detained by a preset detent force in radial slots of an input sec tion continually rotatable by movement of its support. At the same time, an output section superposed to the input section but uncoupled therefrom, maintains a control mechanism in its normally inoperable relation. In response to an excess velocity being attained, as determined by the magnitude of centrifugal force at which the detent force applied against the balls is exceeded, the balls are slung outwardly to rotatably couple the input and output sections. Rotation of the latter permits the control mechanism to be actuated.

It is therefore an object of the invention to provide a novel speed-sensing device for mechanically triggering a control mechanism.

It is a further object of the invention to provide an improved speed-sensing device as in the aforesaid object having higher operational reliability by virtue of increased speed sensitivity as compared to such prior art devices.

It is a further object of the invention to provide a novel speed-sensing device capable of operating on vertically moving components while being unaffected by gravitational drift or the like between the relatively movable parts.

It is a still further object of the invention to provide a novel speed-sensing device as in the aforesaid objects having onsite adjustability for variably presetting the attained excess speed at which the device is to be operatively responsive.

It is a still further object of the invention to provide a novel speed-triggering device that is highly reliable in performance yet is simple in construction and lends itself to being accommodated on a mass majority of relatively moving structures.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a crane in elevation as exemplary apparatus embodying the actuating device hereof;

FIG. 2 is an isometric view partially in section of the actuator in accordance herewith;

FIG. 3 is a longitudinal elevation of the actuator assembly;

FIG. 4 is an end elevation of the actuator assembly;

FIG. 5 is a longitudinal section taken substantially along the lines 5-5 of FIG. 4;

FIG. 6 is a sectional elevation taken substantially along the lines 6-6 of FIG. 3; and

FIG. 7 is a fragmentary end elevation taken substantially from the position 7-7 of FIG. 3.

Referring now to the drawings and particularly to FIG. 1, the actuator mechanism hereof is designated 10 and is shown for purposes of disclosure mounted onto a stacker crane 12 which can comprise a type disclosed for example in Deligt U.S. Pat. No. 3,250,402 incorporated herein by reference. The crane briefly comprises a trolley assembly indicated at 15 including a plurality of wheels 16 for riding along a pair of parallel rails 17 suitably supported within the facility to be served by the crane. Depending from the carriage is a mast assembly 18 comprising a fixed mast selection 19 supported and secured vertically relative to trolley 15. Telescopically arranged over fixed mast section 19 is an intermediate mast section 22 guided for elevating movement by means of elongated rails 23 secured extending longitudinally along opposite vertical sides of fixed mast 19. A plurality of rollers 24, carried by the intermediate mast, engage opposite sides of each rail 23 to provide rolling movement of section 22 relative to section 19. Telescopically mounted for elevating movement near the lower end of section 22 is a load-engaging section 25 including laterally extending forks 26 on which the work load is to be carried. Vertical rail 28 secured on section 22 and engaged by rollers 29 guides vertical movement of section 25.

The lifting force for elevating the components is effected via cables (not shown) from a hoist assembly on trolley 15. Under normal conditions of operation, desired elevations of forks 26 can be readily adjusted by application of hoisting power and when power is disconnected relative elevations of respective components are supported fixedly maintained. In the event of failure in the support mechanism, the crane is equipped with a safety brake 30, which may be of a type disclosed in the aforementioned cofiledpatent application of Paulssen and Johnston, and which is triggered into operation by the actuator mechanism 10 in accordance herewith.

For a more specific description of the actuator hereof, attention is now also directed to FIGS. 2-7. As can be seen, the entire unit is supported via a frame assembly 35 secured welded to the topside of intermediate mast 22 and consisting of a horizontally extending platform 36 and upright end sup-

I ports

37 and 38. Being secured to the intermediate mast, the frame and actuator assembly will move vertically in conjunction therewith.

In order to sense velocity of the mast when moving, there is provided a reference tracking surface in the form of a vertically extending elongated chain 42 secured at opposite ends to upper and lower face portions of fixed mast 19. At its upper end the chain is secured to a bracket 43 and at its lower end is secured to a block 44. Associated with block 44 is an integral stud 45 depending downward through a clevised bracket 46 whereby a coiled spring 47 compressed between the underside of bracket 46 and a nut washer 48 maintains the chain continuously taut and free of slack. As most clearly shown in FIG. 4, the chain 42 is reeved to pass over

idler sprockets

52 and 53 and drive sprocket 54. Each of the idler sprockets are secured to a stub shaft 55 (FIG. 5) rotatably mounted in bearings 56 which are supported in frame end support 37. Drive sprocket 54 is secured to a main shaft 57 rotatably supported at opposite ends in

bearings

58 and 59 which in turn are supported in frame end supports 27 and 38 respectively.

Drive sprocket 54 being in constant mesh relation with chain 42, transmits relative velocity attained by intermediate mast 22 during the course of its movement to the actuator unit at all times by means of the input provided from sprocket 54 to main shaft 57. The input thereby provided is transmitted to sheavelike coupling member 64 secured to shaft 57 via a key 65. For reasons as will be explained, the coupling includes an annular shouldered recess 66 on its rearward face 67 for engagement against a friction brake-lining disc 68 and toward which it is constantly urged by means of a Belleville spring washer 69. As will be understood, the axial force imposed between washer 69 and coupling 64 can be adjusted as required by appropriate tightening of locknut 70. Under normal operating conditions, i.e., at velocities of intermediate mast 22, below which a need to actuate safety brake 30 is not required, brake lining 68 acts to directly connect coupling 64 to an input slinger section 75 to effect concomitant rotation thereof.

Slinger section 75 is mounted for rotation on a substantially frictionless bushing 76 secured to the main shaft 57 and comprises a circular casting including an enlarged portion 77 facing brake-lining 68 and a reduced collarlike portion 79 integral and rearward thereof. Defined extending radially inward from the periphery of portion 77 is an annular slot 108 and a plurality of individual angularly displaced bores 78 axially coincident but terminating inward of slot 108. Formed within portion 79 are a plurality of axially extending bores 80 coinciding in angular location as to axially intersect radial bores 78.

Received within each of bores 78 is a steel ball 84 normally detained at the inner extreme thereof in opposition to normally encountered centrifugal forces tending to throw it outwardly by means of a detent mechanism 85 situated in each bore 80. Each detent mechanism 85 is comprised of a ball plunger 86 cup-shaped on its end where in engagement against the ball, a rear plunger 87 and between which is a compressed coil spring 88 acting to impose a retaining force on plunger 86 against the ball. The magnitude of imposed force results from the adjustably preset axial position of flat washer 89 against plunger 87 as set by locknut 90 and effectively regulating the degree of compression imposed on spring 88. By appropriate axial adjustment of nut 90 any desired detent force can be imposed below which the ball is retained against centrifugal forces and above which the ball can escape. Since the centrifugal escape force varies as the square of the rotational speed of slinger 75, it can be suitably preset as required to reflect the operating condition at which the unit is to be responsive.

Comprising the actuator output is an annular trigger collar 94 mounted coaxial and at least partially superposed to slinger 75 but normally supported rotationally disengaged therefrom by means of

ball bearings

95 and 96. The bearings are mounted secured via a retainer 97 and a snapring 98 axially in place onto collar portion 79 of slinger 75. On the left end face of collar 94 as viewed in FIG. and secured by capscrews 102 is a disclike ball coupler member in the form of catcher 103. The catcher is circular on its exterior and on its interior as best shown in FIG. 6 includes a plurality of radially inward fingers 105 received extending within annular slinger slot 108. On the opposite or right end face of trigger collar 94 is an axially extending trigger finger 109 the outwardmost termination of which is inwardly dished on its underside (FIG. 7) to receive roller 110 of a trip arm Ill. The trip arm in turn acts, when in the horizontal relation as illustrated solid in the drawings, to maintain push rod 112 of brake assembly 30 depressed and the brake disengaged from braking relation as described in the aforementioned cross-referenced application.

Rotational disengagement between the input and output sections of the actuator continues so long as attained velocity of mast 22 is below the correlated detent escape force imposed against balls 84. When slinger velocity as a direct function of mast velocity causes the generated centrifugal forces to exceed the escape force, balls 84 are slung outwardly as shown dashed in FIG. 6 into catcher finger pockets 114 to rotatably couple the input and output sections. The coupled relation immediately accelerates catcher 103 into a rotational movement, causing trigger finger 109 to likewise rotate as shown in FIG. 7 away from roller 110. With suppression of roller 110 removed trip arm 111 is permitted to be pushed upwardly by the bias action of push rod 112 to effect operation of safety brake 30. I

Since the brake engages almost instantaneously, descending movement of the intermediate mast is immediately arrested causing a consequent substantially instant rotational deceleration of coupling member 64. In order therefore to minimize and dissipate the shock impact forces associated with the turning moment at the time of coupling arrest, slinger gradually decelerates by the frictional relation imposed against brakelining 68. When the latter deceleration begins a relative rotational displacement occurs between slinger 75 and catcher 103 by virtue of the relatively greater rotational velocity of the latter compared to the former. With catcher 103 rotationally leading the slinger, back rake 115 of catcher fingers 105 gradually force each of the balls inward of slots 78 until held by their respective detents to again disengage the actuator output. Thereafter roller 110 is manually replaced under trigger finger 109 and the normal operating relation of the actuator and brake can be resumed.

in operation, the travel velocity of mast section 22 is continually sensed and under normal conditions is transmitted via sprocket 54 through coupling 64 to slinger 75. For so long as the sensed velocity continues below the level at which the actuator is operatively responsive catcher 103 is rotationally disengaged from slinger 75 while finger 109 engageably maintains the control mechanism for brake 30 inoperative. When mast 22 is accelerated to a predetermined velocity inducing a centrifugal force exceeding the detent force imposed by detent mechanism 85, the balls are slung outwardly to couple the input and output sections. At that point in time the output section is instantly accelerated moving trigger finger 109 out from over roller 110 and permitting arm 11] to rise and brake 30 to engage.

By the above description, there has been disclosed a novel actuating device that is simple in construction yet more highly reliable and velocity-responsive than such devices in the prior art. By means of adjustment provided by locknut 90, the operational level at which the actuator will respond can be preset to any desired operative condition at which the balls 84 will escape from their detents 85 for actuating the device. At the same time the tension imposed by locknut 70 can be used to dissipate the shock impact forces as required as a function of turning mass and velocities to be expected. While the use of four balls 84 at displacement have been shown, it should be evident that the device is operable with as few as one ball to effect the desired coupling rotation. Conversely, an increase in ball quantity is limited only by practical considerations, it being recognized that increased quantities tend to increase reliability and reduce consequent reaction time. it can be appreciated that reaction time could be critical for applications such as the embodiment described in avoiding delayed braking during which energy buildup would occur. Moreover, while the device has been described in a preferred embodiment as principally intended for use in a stacker crane, it is not intended to be so limited since it obviously has many applications in other fields having components with variable relative velocities linear or rotary requiring some form of signal generation on obtaining a predetermined relative velocity between them. Likewise it is recognized that some control mechanisms in contrast to that described would be engageable only during rotation of the output section.

Since many charges could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows;

1. A triggering device for actuating operation of a control mechanism in response to a predetermined velocity difference between relatively moving parts comprising in combination:

a. elongated tracking means secured to a first of said relatively moving parts and extending in the direction of movement;

b. velocity sensing means secured to the other of said relatively moving parts and operatively engaging said tracking means for generating an operative movement at a velocity correlated to the relative velocity difference between said parts;

0. actuating means operative between engageable and disengageable relation with a control mechanism to be actuated, said actuating means being mounted for rotation and adapted when unrotated to effect one of said relations with a control mechanism to be actuated and adapted when rotated to effect the other of said relations with a control mechanism to be actuated; and

d. coupling means centrifugally actuated at velocities exceeding said predetermined velocity difference to operatively couple the operative movement of said velocity sensing means and said actuating means for effecting a change in the latter from its unrotated to its rotated relatron.

2. A triggering device according to claim 1 in which there is included rotational means connected to said velocity sensing means to be rotatable at a rate correlated to the velocity of said sensing means and said actuating means is supported juxtaposed to said rotational means rotationally free thereof.

3. A triggering device for actuating operation of a control mechanism in response to a predetermined velocity difference between relatively moving parts comprising in combination:

. first rotational means connected to said velocity sensing means to be rotatable at a rate correlated to the velocity of said sensing means;

d. second rotational means arranged juxtaposed to said first rotational means rotationally free thereof and adapted to operatively engage a control mechanism to be actuated; and

e. coupling means centrifugally actuated at velocities exceeding said predetermined velocity difference to couple said first and second rotational means whereby to operatively disengage said second rotational means from a control mechanism with which it is operatively engaged.

4. A triggering device according to claim 3 in which said first rotational means includes at least one bore defined radially extending inward from a rotational periphery and said coupling means includes ball means in said at least one bore centrifugally moveable to couple said first and second rotational means at velocities at least equal to said predetermined velocity.

5. A triggering device according to claim 4 including detent means detaining said ball means uncoupled from said second rotational means at velocities below said predetermined velocity.

6. A triggering device according to claim 5 in which said detent means includes means to presettably adjust the detent force thereof for a desired predetermined velocity at which said ball means are centrifugally movable into said coupling relation.

7. A triggering device according to claim 3 in which at least a portion of said second rotational means is positioned coaxially superposed to at least a portion of said first rotational means.

8. A triggering device according to claim 7 in which said first rotational means includes a friction lining intermediately engaging opposite component parts thereof.

9. A triggering device according to claim 8 including means to presettably adjust the frictional force imposed between said opposite components and said friction lining.

10. A triggering device according to claim 6 in which said tracking means comprises an elongated chain and said velocity sensing means comprises a rotatable sprocket in drive-mesh relation with said chain.

11. A triggering device according to claim 8 in which said first rotational means includes a plurality of bores defined radially extending inward from a' rotational periphery, said coupling means includes ball means in each of said bores centrifugally moveable to couple first and second rotational means at velocities at least equal to said predetermined velocity, and said second rotational means includes an annular coupler member located substantially axially coincident with the axes of said radial bores, said coupler member including pockets defined on its radially inner surface to receive said balls for effecting said coupling relation.

12. A triggering device according the claim 11 in which the radially inner extending surface of said coupler member includes a back rake intermediate said pockets effective when the relative velocities of said second rotational means exceeds that of said first rotational means to return said ball means into uncoupling relation within said bores.

Claims

1. A triggering device for actuating operation of a control mechanism in response to a predetermined velocity difference between relatively moving parts comprising in combination: a. elongated tracking means secured to a first of said relatively moving parts and extending in the direction of movement; b. velocity sensing means secured to the other of said relatively moving parts and operatively engaging said tracking means for generating an operative movement at a velocity correlated to the relative velocity difference between said parts; c. actuating means operative between engageable and disengageable relation with a control mechanism to be actuated, said actuating means being mounted for rotation and adapted when unrotated to effect one of said relations with a control mechanism to be actuated and adapted when rotated to effect the other of said relations with a control mechanism to be actuated; and d. coupling means centrifugally actuated at velocities exceeding said predetermined velocity difference to operatively couple the operative movement of said velocity sensing means and said actuating means for effecting a change in the latter from its unrotated to its rotated relation.

3. A triggering device for actuating operation of a control mechanism in response to a predetermined velocity difference between relatively moving parts comprising in combination: a. elongated tracking means secured to a first of said relatively moving parts and extending in the direction of movement; b. velocity sensing means secured to the other of said relatively moving parts and operatively engaging said tracking means for generating an operative movement at a velocity correlated to the relative velocity difference between said parts; c. first rotational means connected to said velocity sensing means to be rotatable at a rate correlated to the velocity of said sensing means; d. second rotational means arranged juxtaposed to said first rotational means rotationally free thereof and adapted to operatively engage a control mechanism to be actuated; and e. coupling means centrifugally actuated at velocities exceeding said predetermined velocity difference to couple said first and second rotational means whereby to operatively disengage said second rotational means from a control mechanism with which it is operatively engaged.

11. A triggering device according to claim 8 in which said first rotational means includes a plurality of bores defined radially extending inward from a rotational periphery, said coupling means includes ball means in each of said bores centrifugally moveable to couple first and second rotational means at velocities at least equal to said predetermined velocity, and said second rotational means includes an annular coupler member located substantially axially coincident with the axes of said radial bores, said coupler member including pockets defined on its radially inner surface to receive said balls for effecting said coupling relation.