US2837930A

US2837930A - Non-jamming drive actuator

Info

Publication number: US2837930A
Application number: US572726A
Authority: US
Inventors: Charles F Desmond
Original assignee: Houdaille Industries Inc
Current assignee: Houdaille Industries Inc
Priority date: 1956-03-20
Filing date: 1956-03-20
Publication date: 1958-06-10
Anticipated expiration: 1975-06-10

Description

June 10, 1958 c DESMOND 2,837,930

NON-JAMMING DRIVE ACTUATOR Filed March 20, 1956 3 Sheets-Sheet 1 I=l Fl fig WZ4%MM, FF 5" i J s l imp June W, 1958 c. F. DESMOND NQN-JAMMING DRIVE ACTUATOR Filed March 20, 1956 5 Sheets-Sheet 2 .257 V'EIY far (1445155 F flay/vamp Unite States 2,337,930 Patented June 10, 1958 Flee NON-JAMMING DRIVE ACTUATOR Charles F. Desmond, Wiiliamsville, N. Y., assignor to Houdaille Industries, Inc., Detroit, Mich, a corporation of Michigan Application March 20, 1956, Serial No. 572,726

1 Claim. (Cl. 74-4243) This invention relates generally to mechanical movements and more particularly relates to a screw-type actuator of the type having load-release means or socalled free wheeling whereby the operative components of the mechanism will be released at positions corre sponding to the end limit positions of relative movement.

ltis an object of the present invention to provide an improved mechanical movement incorporating loadre lease means.

Another object of the present invention is to provide an improved screw-type actuator having a free wheeling characteristic at the end limit positions of travel.

Another object of the present invention is to provide a new and improvedactuator combining a spring clutch with a screw-type actuator.

Another object of the present invention is to provide a screw actuator embodying a spring clutch wherein a single spring can be utilized and may be selectively inactivated by stop means at either end of the actuating device.

Another object of the present invention is to provide actuating means incorporating a reduced number of simplified parts which are easy to fabricate and which are rugged and durable in use.

Many other features, advantages and additional obiects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred structural embodiment of a screw-type actuator incorporating the principles of the present invention is shown by way of illustrative example.

On thedrawings:

Figure l is a plan elevational view of an automotive seat adjuster mechanism incorporating a plurality of actuating units embodying the principles of the present invention;

Figure 2 is an end elevational view taken substantially on line II-Il of Figure 1 illustrating details of the linkage and slide track support means provided for the seat adjuster mechanism of Figure l;

Figure 3 is a cross-sectional view taken generally on line III--III of Figure 1 and has parts broken away and parts shown in cross-section to illustrate additional details of structure of a representative actuating unit incorporating the principles of the present invention;

Figure 4 is an enlarged cross-sectional view similar to Figure 3 but showing additional details of construction of the actuator unit;

Figure 5 is a fragmentary cross-sectional view with parts shown in elevation taken generally on line V-V of Figure l;

Figure 6 is an end eievational view of the actuator unit shown in Figure 4;

Figure 7 is an elevational view of the nut member and the coil spring means of the device of Figure 4; and

Figures 8 a'nd9 are end elevational views of opposite ends of t .e structure of Figure 7.

As shown on the drawings:

The screw-type actuator of the present invention comprises a mechanical movement of general utility, however, in order to best illustrate the construction and use of the actuator, a representative application of the actuator, is referred to for the purposes of this disclosure, namely, a seat-adjuster mechanism for an automotive vehicle as shown generally in Figure 1 by the reference numeral 10. A seat cushion 11 is carried by a generally rectangular frame 12 and is adapted to be adjustably carried on a relatively stationary support 13 which may conveniently comprise the body portion of an automobile. Accordingly, at opposite ends of the frame 12, there is provided slide track means 14- secured to the underside of the frame 12 by means of a front bracket 16 and a rear bracket 17. Although not all of the structural elements of the slide track mechanism are necessary to a proper understanding of the principles of the present invention, those versed in the art will appreciate that components of the slide track means 14 can be carried by the support 13 through bracket means which are indicated herein generally by the reference numeral (Figure 2). One of the actuator units of the present invention indicated generally by the reference A (Figure 1) is provided to selectively move the seat frame 12 forwardly and backwardly between end limit positions of forward and backward adjustment.

For further effecting either a platform lift of the seat frame 12 or to effect selective tilting of the seat frame 12, a linkage assembly is provided for accommodating vertical movements of the frame 12 as Well as forward and backward movements permitted by the slide track 14. Thus there is provided a bracket 18 at the front of the seat adjuster mechanism 19 having a pivot 19 carrying a bell crank 2% including a first arm 21 and a second arm 22.

At the rear of the mechanism, there is provided a bracket 23 which is fastened to the support 13 having a pivot mounting 2d pivotally supporting a pivot bracket 26 which, in turn, provides a pivot mounting 27 to which is connected in pivotal assembly one arm 28 of a bell crank 29, the second arm of the bell crank 29 being indicated at 30. A guide bracket 31 fastened to the bracket means 15 provides an elongated slot or guideway 32 in which is received a roller 33 supported by the bell crank 29.

A pivotal connection indicated at 34 (Figure 2) connects the arm 30 of the bell crank 29 to a bar member 36 extending towards the forward end of the seat adjuster mechanism 10 and pivotally connected at its other end to the arm member 22 of the bell crank 29 as indicated at 37.

The arm 21 of the bell crank carries a cross rod 38 which is also shown in Figure 3, the cross rod 38 being connected at opposite ends to the bracket means 15.

A coil spring 39 is connected to the crank arm of the bell crank 29 as at 40 and is connected as at 41 to the support 13.

As shown in Figure l, a screw actuator unit B is provided for effecting a tilting operation of the mechanism 10 and an actuator unit indicated at C is provided for effecting a selective platform lift adjustment of the mechanism 10.

Referring briefly to the operational characteristics of the three units A, B and C, it will be noted that the unit A has relatively extensible members, one of the members being pivotally connected to a support bracket carried by the support structure 13. The other extensible member is connected to the seat frame 12 by means of a bracket 42 having a pin 42a extending therethrough. Thus, upon relative extension or contraction of the extensible elements, movement is produced between the support structure 13 and the frame 12,

tions

62 and 63 at opposite ends thereof.

The unit C is connected to a bracket 43 carried by the support structure 13 at one end and includes a bracket 44 connected to the cross bar 38 at the other end. Thus, upon relative extension or contractual adjustment of the extensible members of the unit C, the cross bar 38 is moved within a confined path determined by the bell crank since the cross bar 33 is supported by the crank arms 21 of the supporting structures at opposite sides of the seat mechanism 10.

Moreover, when the bell crank 20 is actuated, the crank arm 22 will transmit relative movement through the bar member 36 to the crank arm of the bell crank 29, whereupon the entire bell crank 29 will pivot around the pivot mounting 27 and both ends of the seat frame 12 will be elevated in unison to afford a platform lift adjustment.

The tilting unit B is pivotally supported by a bracket member 46 at one end and is pivotally connected to a second bracket indicated at 48. The bracket 46 has a pivotal connection as at 49 with the lever arm 58 connected to the cross rod 38. The bracket 48 is connected to a second cross rod indicated at 51 which is connected at opposite ends to corresponding pivot frame members previously indicated at 26. Thus, whenever relative extension occurs through actuation of the tilting unit B, the cross rod 51 will operate to pivot the pivot bracket 26 about the axis of the pivot mounting 24, which incidentally, is coincident with the axis of the cross rod 51 thereby swinging the pivot mounting 27 and producing a corresponding movement of the bell crank 29 and specifically the roller 33. During this tilting operation, the pivot mounting 34 is restrained since the bar member 36 is connected thereto and is in turn connected to the bell crank member 20. The tilting unit is carried by the bracket means 46, however, and since the bracket means 46 is connected to the cross rod 38, no pivotal movement of the bell crank 20 occurs thereby insuring a tilting movement of the bell crank 29 about the axis 24 and a consequent tilting of the seat frame 12.

Although three separate actuator units are illustrated in connection with the seat adjuster mechanism 10, it will be appreciated that each of the units, A, B and C can be constructed along substantially similar lines. Accordingly, only one of the units will be described in detail in connection with the disclosure of the structural and functional features of the screw-type actuator of the present invention.

The actuator unit B comprises inner and outer parts provided by a nut member and a retainer sleeve 61, respectively. The nut member 60 is a generally cylindrical element having a peripheral outer surface and is particularly characterized by reduced diameter por- At the reduced end 63, there is'mountcd a radially outwardly extending flange 64 which is fastened in firm assembly to the nut member 60 as by means of welding indicated at At the reduced end 62, a fiange providing member 67 is fastened in firm assembly with the nut member 60 by means of a set screw 68.

The retainer sleeve 61 is a sleeve-like element having an open-ended bore providing a cylindrical inner surface 69. The outer peripheral surface of the retainer sleeve 61 is threaded as at 70 and thereby may be threadedly assembled in the end of a tubular member 71 adapted to be connected to the means to be actuated. T hus. in the specific application of the actuator unit B, as shown in Figure 3, the tubular member 71 is threadedly connected to a second tubular member 73 and is retained in locked position thereon by means of a lock nut 74. The tubular member 73 has a bracket 76 connected thereto which, in turn, is pivoted as at 77 to the lever arm 48. To secure 'ly lock the retainer sleeve 61 in firm assembly with the tubular member 71, one or more set screws 73 are threaded through the tubular member 71 into locking engagement with the retainer sleeve 61.

The inner surface 69 of the sleeve member 61 is substantially coextensive with the peripheral surface 65 provided on the nut member 60. Interconnecting means are interposed between the confronting

surfaces

69 and 65 to provide a limited frictional connection between the parts. In accordance with the principles of the present invention, the interconnecting means takes the form of a helically wound coil spring 30 having a plurality of coils arranged with the coiling axis coaxial with respect to the axis of the nut member 60 and encircling the peripheral surface 65 thereof. The normal self-energizing action of the coil spring 80 tending to unwind the springs results in a frictional engagement between the peripheral surfaces herein indicated at 81 of the spring coils with the engagement surface 69. Whenever such engagement occurs, the nut member 60 is held against relative rotation with respect to the retainer sleeve 61.

As is particularly shown in Figures 6 and 9, the flange member 64 is particularly characterized by the formation therein of a notch or slot 82, shoulders being indicated at 83 and 84 at opposite sides of the slot. Confined within the slot for limited movement prescribed by the

shoulders

83 and 84, is a tang 86 which is angularly offset at one end of the coil spring 80.

The flange 67 provided at the opposite end of the nut member 60 has a notch or slot 87 formed therein,

shoulders

88 and 89 being provided at opposite sides of the slot 87 and serving to confine a tang 90 angularly offset at the opposite end of the coil spring 80.

In accordance with the principles of the present invention, a screw shaft 91, provided on its peripheral surface with a helical thread 92, is threaded through the nut member 60 and upon relative rotation between the screw shaft 91 and the nut member 60, the two parts are axially moved with respect to one another.

When the spring coils 80 couple the nut member 60 to the retainer sleeve 61, the axial advance of the nut results in the translatable adjustment of the tubular member 71 and the corresponding means to be actuated associated therewith.

By virtue of the structure thus provided, the drive nut or nut member 60 is threaded on the mating drive screw or screw shaft 91 and is free to rotate thereupon. Interposed between the driven collar or retainer sleeve 61 and the nut member 68 is the helical spring 80 with the oppositely extending

axial tangs

86 and 90. The rotation of the spring 80 is limited by the shape of the notches or

slots

82 and 87 in the thrust rings or

flanges

64 and 67, in other words, by the spacing dimension between the circumferentially spaced

shoulders

83 and 84 and 88 and 89, respectively. The thrust rings or

flanges

64 and 67 also limit the axial motion of the retainer sleeve 61 since it will be noted that the end surfaces 61a and 61b closely confront the adjoining side faces of the

flange members

67 and 64, respectively.

It is contemplated in accordance with the principles of the present invention that the screw shaft 91 be provided with stop means at axially spaced or longitudinally separated points corresponding to the limits of adjustment contemplated in accordance with the specific actuator application. In the present embodiment, there is provided a stop pin 94 at one end of the screw shaft 91 and a second stop pin 96 (Figure 3) at the other end of the screw shaft 91.

When the screw shaft 91 is rotated, the nut is axially advanced until one of the stop pins 94 or 96 engages a

corresponding spring tang

90 or 86. Such engagement will tend to rotate the entire coil spring 80, however, the opposite spring tang, for example, as shown in Figure 4, the spring tang 86, will then engage the shoulder 84 on its corresponding thrust ring or flange 64 whereupon further rotation of the spring will reduce the outside diameter of the coils, thereby contracting the bearing surfaces 81 and reducing the radial coupling force between the peripheral surfaces '81 of the coil spring 80 and thesurface 60 of the retainer ring 61. This action declutches the spring 80 from the driven collar or retainer sleeve 61 whereupon the screw shaft 91 together with the nut member 60, the thrust rings or

flanges

64 and 67 and the coil spring 80 will revolve as a unit with respect to the tubular member 71 and the retainer ring 61 with no further relative axial motion between the nut member 60 and the screw shaft 91.

As shown in Figure 3, the screw shaft 91 has an extension 101 journalled in a pair of spaced

bearings

102 and 103 carried in a gear box 104. A gear 106 is carried by the extension 101 and meshes with a worm 107 attached to the power take-off shaft 108 of an electric motor 109 mounted in firm assembly on the gear box 104. A suitable mounting bracket 110 is provided to carry the gear box 104 and the electric motor 109 in pivotal assembly, for example, on the bracket 46 in the case of the unit B, the pivot mounting being indicated at 111. As shown in Figure 5, the power take-off shaft 108 is provided with bearing support as at 112 on the free end thereof adjacent the worm 107.

In operation, upon rotation of the screw shaft 91, with no stop means in engagement with the coil spring means, the tendency of the nut 60 to rotate in the same direction as the screw shaft 91, due to the torque resulting from friction between the nut 60 and the screw shaft 91 is resisted by the self-energizing action of the coil spring means, which in unwinding in the confined space provided between the walls of the thrust or retainer member 61 and the adjoining space expands and exerts a radial force against the thrust and retainer member 61, effectively preventing the nut 60 from rotating within the thrust and retainer member 61. The thrust and retainer member 61, then transmits the axial motion of the nut to a device to be translated.

When the nut 60 reaches a stop pin 94 or 96 which is a limit of the axial motion, the projected

end

90 or 86 of the spring 80 engages a corresponding pin 94 or 96 whereupon the spring 80 will wind-up, decreasing the radial force between the abutting surfaces whereupon the nut 60 will rotate within the retainer 61 at the same velocity as the screw shaft 91.

Although various minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention: 1

A translation adjuster comprising a motor having a gear box housing, means for pivotally securing said gear box housing and said motor on a stationary support, a screw shaft projecting out of said gear box housing and being rotatably driven in selected angular direction by said motor, a pair of axially spaced stop pins on said screw shaft, a nut member threaded on said screw shaft and movable between said stop pins upon relative rotation between said nut member and said screw shaft, frame means to be translatably adjusted including a nonrotatable thrust member circumjacent said nut member, and a spring clutch between said collar and said nut member comprising a coil spring having the coiling axis coaxial with the axis of said nut member and said screw shaft and having oppositely extending tangs on the ends thereof, a thrust ring at each end of said nut member, each thrust ring having a slot formed therein confining a corresponding tang for limited angular movement, the self-energizing action of said coil spring effecting frictional engagement between the peripheral surfaces of said coils and said collar, said stop pins on said shaft engaging said tangs when said tangs are moved to limit positions by relative axial movement of said nut member and said screw shaft to wind up said coil spring, thereby decreasing the diameter of the coils thereof and permitting rotation of said nut member relative to said thrust member and together with said screw shaft at the limit positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,345,182 Corber Mar. 28, 1944 2,446,393 Russell Aug. 3, 1948 2,540,009 Pepper Jan. 30, 1951 2,660,028 Geyer Nov. 24, 1953 2,765,024 Brundage Oct. 2, 1956