Locking mechanism for pedestal seat

Abstract

Locking mechanism for a rotatable pedestal mounted seat is actuated by a spring biased handle which is mounted on the seat and which moves with the seat and carries an axially movable cam locking assembly and a centering guide member. When the locking mechanism is released, an outer tube carried by the seat is free to rotate about an inner tube carried by a floor mounted pedestal. When the seat is rotated to its aligned forward position, the centering guide member is snapped by the force of the handle mounted spring into a slot in the inner tube. The snap movement of a portion of the guide member into the slot will simultaneously rotate two cooperating portions of the cam assembly relative to each other so as to draw a pair of brackets welded to the outer tube toward each other. Since the outer tube is longitudinally split between the brackets and circumferentially slotted above and below the brackets, its inner diameter is reduced when the brackets are drawn together by the locking assembly so as to firmly bind against the inner tube and prevent any wobbling taking place between the two tubes. An adjustment nut member cooperates with the cam assembly to extend the range of the locking mechanism in order to accommodate large manufacturing tolerances in the tubes as well as wear.

Description

BACKGROUND OF THE INVENTION

With the development of motor home and other multi-use vehicles a need has arisen for seats which can be rotated from a forward facing driving position to a position facing the interior of the vehicle. In order that the seat will be firmly anchored to the floor when the vehicle is in motion, the seat is usually mounted on a pedestal comprising a pair of telescoped tubes which can be locked against rotation. Examples of prior art locking mechanisms can be found in U.S. Pat. No. 3,758,063 and in U.S. Pat. application Ser. No. 430,318 filed on Jan. 2, 1974, each of which has been assigned to a common assignee.

SUMMARY

It is among the objects of this invention to provide a rotatable vehicle seat support which can be locked in at least one predetermined position of rotation and then be easily and quickly released and rotated to any other desired position.

It is another object of this invention to provide a locking mechanism which will automatically lock the seat against rotation and wobbling when the seat is rotated to its driving position.

These and other objects are accomplished by the improved mechanism of the present invention wherein a seat is provided with an outer tubular member projecting downwardly from its bottom into telescopic surrounding relation to an inner tubular member projecting upwardly from a floor mounted pedestal. An axial portion of the outer tube is split in both a longitudinal and circumferential direction and a pair of brackets extend outwardly from the outer tube on opposite sides of the longitudinally split portion. An elongated shaft having a handle portion on one end is mounted in the brackets and carries a cam assembly near its outer end which forces the brackets toward each other when the handle is rotated in one direction. A first cam member is keyed to the shaft so that rotation of the handle will move a ramp-shaped cam surface on the cam member in contact with a corresponding ramp-shaped cam surface on a second cam member which is fixed against rotation on the outer side of one of the brackets. Since the cam assembly is captured on the shaft between one of the brackets and an adjustable nut, rotation of its cam members relative to each other by rotation of the handle and shaft will force the brackets toward each other, tend to close the longitudinally split portion, and cause the outer tube to contact and tightly engage the inner tube. When the cam assembly lengthens and forces the brackets towards each other, the inner and outer tubes are forced into tight engagement with each other in at least three regions around their circumference so as to eliminate any looseness between the tubes which could cause rattles or vibrations during vehicle operation. A centering guide or detent member positioned on the shaft between the brackets is adapted to be moved into and out of a slot in the inner tube when the seat is aligned in its forward driving position. The centering guide member cooperates with the sides of the slot to prevent rotary motion. A spring mounted on the shaft and in engagement with one of the brackets biases the centering guide member towards the inner tube so that rotation of the seat to its forward position will cause the centering member to snap into the slot and the cam assembly to rotate and compress the outer tube against the inner tube.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view, with portions broken away, of a pedestal seat incorporating the invention;

FIG. 2 is a fragmentary front view of the locking mechanism shown in FIG. 1 in its free position;

FIG. 3 is a fragmentary front view of the locking mechanism shown in FIG. 1 in its locked position;

FIG. 4 is a top sectional view taken on lines 4--4 of FIG. 2;

FIG. 5 is a top sectional view taken on lines 5--5 of FIG. 3;

FIG. 6 is a fragmentary side sectional view taken on lines 6--6 of FIG. 2;

FIG. 7 is a fragmentary side sectional view taken on lines 7--7 of FIG. 3;

FIG. 8 is a side view similar to FIG. 7 but showing the centering guide stop member in its stop position; and

FIG. 9 is an exploded view of the cam assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a vehicle seat structure indicated generally at 10 is shown as comprising a pedestal floor mount 12 including an integral inner support tube 14. Telescopically engaged with the inner tube 14 is an outer tube 16 welded at 18, 20 to the seat frame 24. A pair of upper and lower horizontal slots 28 and a vertical slot 30 formed in an H-shaped pattern (turned 90.degree.) in the outer tube 16 form a pair of tube segments 32, 34 which can be moved relative to the remainder of the tube 16 so as to be compressed against the inner tube 14. The segments 32, 34 are moved by brackets 36, 38 which are welded to them at 40, 42 by a locking assembly indicated generally at 44. The locking assembly 44 comprises a shaft 46 having a handle 48 at its outer end and a threaded portion 50 at its inner end. The shaft 46 is mounted for rotation in frame 24 and brackets 36, 38 and carries a first cam member 52 splined to a flat 53 on the shaft and a second cam member 54 keyed at 56 to bracket 38. The cams cooperate to move the brackets 36, 38 toward and away from each other.

The operation of the mechanism can be briefly described as follows: assuming the seat 10 is in its locked forward facing position (FIG. 3) the handle 48 is turned counterclockwise to rotate the shaft 46 and the rotary first cam member 52 so as to remove cam pressure from the brackets 36, 38 and privot the centering guide or detent member 58 out of the slot 60 in the inner tube 14. The handle 48 can be released as soon as the seat 10 is rotated a small distance away from the slot 60 (FIGS. 1 and 2) and the seat can then be rotated to any position. The seat can be re-aligned in its forward position (FIG. 3) without touching the handle 48 by simply rotating the seat until the spring biased centering guide member 58 falls into the slot 60. Although the seat is generally sufficiently well locked against wobbling as well as rotation in this position due to the force applied by the spring 62 to rotate shaft 46 and member 58 to their FIG. 3 position, it is possible to rotate the handle 48 clockwise an additional amount to cause the cams 52, 54 to rotate further relative to each other to more firmly compress the outer tube 16 against the inner tube 14. This additional compression or binding action positively insures that the tubes will not rattle or wobble against each other or against the centering guide member 58 during use. Although the clamping range of the cam assembly 44 can accommodate rather large manufacturing tolerances in the tubes 14, 16 as well as the effects of wear on the tubes during use, the clamping range is preferably extended by the use of an adjustable abutment member such as threaded nut 64 on the end of the shaft 46. Since the abutment member 64 can be adjusted to provide any desired amount of preload force against the cam assembly 44 and brackets 36, 38 it will be obvious that the cam surfaces 66, 68 of the first and second cam members 52, 54 do not need to provide an extremely great adjustment range and therefore can be designed with various profiles. For example, the locking force provided by the cams can be made to increase steadily as the handle 48 is rotated or can be made to vary in a non-uniform manner. To illustrate, the cam angles at one or both ends of the range of movement of the handle could be less than at the center of the range to make it easier to start manual movement of the handle 48. Stop means 70, 72 are provided on the cam assembly and stop means 74 (FIG. 8) are provided on the centering guide member 58 to limit rotational movement on the handle 48 in an unlocking and locking direction, respectively.

By comparing FIGS. 2 and 4 to FIGS. 3 and 5 the locking action that takes place as handle 48 is rotated is readily evident. For example, as the brackets 36, 38 are forced toward each other as the handle 48 and cam 52 are rotated, the tube segments 32, 34 are forced into frictional engagement with the inner tube 14 in regions "A" and "B" (FIG. 5). Simultaneously, the tubes 14, 16 are also forced into contact in region "C." The tubes 14, 16 are preferably sized so as to be spaced quite closely to each other. However, the spacing between the tubes shown in FIGS. 4 and 5 is greatly exaggerated for clarity in illustrating the fact that only the split portion of tube 16 comprising portions 32, 34 can change its radius of curvature during locking. The remainder of the tube 16 has a non-changeable diameter due to the fact that it is welded at axially spaced points 18, 20 to the seat frame 24. The brackets 36, 38 are normally biased to the position shown in FIGS. 2 and 4 by the resiliency of the outer tube 16. As the handle 48 is rotated to the locking position shown in FIGS. 3 and 5, the brackets are forced toward each other. Bracket 36 is positioned on the shaft 46 to the right of a washer 78 and stop pin 80 passing through the shaft and bracket 38 is positioned on the shaft to the left of adjustment nut 64 and the cam assembly 44. An initial preload pressure is applied to the brackets by tightening nut 64 until the tubes 14, 16 are just short of engagement with the handle 48 in its unlocked FIG. 1 position. Thus preloaded, the tubes will be locked as rotation of the handle 48 to its FIG. 3 position causes cam members 52 and 54 to rotate relative to each other and increase in overall length.

FIGS. 6 - 8 show the centering guide member 58 in its unlocked, partially locked and fully locked positions, respectively. The direction in which the member 58 is biased by spring 62 is indicated by an arrow. Since the slot 60 in tube 14 is not aligned with the guide or detent member 58 in FIG. 6, the corner 58' of the guide member 58 rides on the surface of tube 14 until it encounters the slot 60 (FIG. 7), at which time it swings into the slot under the force of the spring 62. This swinging movement not only locks the seat 10 in its pre-aligned forward facing position so as to prevent rotation but also rotates the cam member 52 to force the brackets 36, 38 toward each other and to move the tube portions 32, 34 to their locked position shown in FIG. 5. To provide additional locking force, the handle 48 can be manually pushed down beyond its FIG. 3 position. However, maximum rotation of the shaft 46 is limited by stop portion 74 formed on member 58 which engages the bent over rib portion 38' of bracket 38.

In order to insure correct alignment of guide member 58 and cam 52 relative to shaft 46, the member 58 and cam 52 have inner openings which complement the shape of shaft 46 including its flatted portion 53. Additional locking strength is provided for member 58 by pin 76. Although the locking force provided by the invention is substantial, additional locking restraint in a vertical direction is provided by stud 78 attached to tube 14 which receives nut 80. Nut 80 overlies curved slot 82 formed in frame 24 and prevents vertical relative movement of tubes 14 and 16.

Although tubes 14, 16 have been shown as being cylindrical in form it is contemplated that these members could be generally conical.

Claims

We claim as our invention:

1. In a rotatable seat for a motor vehicle having an outer longitudinally slotted tubular member attached to the seat frame and a telescoped inner tubular member attached to a base, the improvement comprising bracket means affixed to a longitudinal portion of said outer tubular member on opposite sides of the longitudinal slot; shaft means carried by said bracket means; cam means and detent means carried by said shaft means; handle means on said shaft means for rotating said shaft means, said cam means and said detent means; an aperture means formed in said inner tube, said aperture means being positioned relative to said longitudinal slot so that when the seat is in its driving position the aperture means is aligned with the longitudinal slot and with said detent means whereby rotation of said handle means will cause said detent means, which is mounted for rotation with said shaft means, to move into or out of said aperture means and will cause said cam means to cooperate with said bracket means on said opposite sides of said slot to cause said bracket means to be moved toward each other so as to compress said longitudinal portion of said outer tubular member to reduce its diameter and force its inner surface into binding frictional contact with the outer surface of said inner tubular member.

2. The seat of claim 1 characterized in that said cam means includes a first cam member which is fixed to said shaft means for rotation therewith and relative to a second cam member which is fixed relative to a portion of said bracket means, whereby rotation of said shaft means by said handle means will cause cam surfaces on said cam members to engage each other and axially move said cam members relative to each other.

3. The seat of claim 2 characterized in that said cam members each have complementary helical ramp surfaces on their engaging ends.

4. The seat of claim 1 characterized in that a spring is mounted on said shaft and connected to said shaft and to said seat frame for biasing said detent means towards said inner tube.

5. The seat of claim 1 characterized in that cooperating detent stop means on said detent means and on said bracket means limit the permissible angular rotation of said shaft means in a locking direction.

6. The seat of claim 2 wherein said shaft means includes shaft stop means for limiting the axial movement of the handle end of said shaft means toward said bracket means.

7. The seat of claim 6 wherein said shaft means includes an adjustable abutment member on the end of said shaft means opposite said handle means, said abutment member being in operative engagement with said first cam member, and said cam means being positioned on said shaft intermediate said abutment member and said bracket means.

8. The seat of claim 2 characterized in that cooperating stop portions on said first and second cam members limit the permissable angular rotation of said shaft means in an unlocking direction.