US2636549A - Platform supporting mechanism - Google Patents

Description

April 28, 1953 vR. G. GELLER '2,636,549

' PLATFORM SUPPORTING MECHANISM 1 Filed July 18, 194'7 2 Sl-IEETS-S-IEET l MINI iii

INVENTOR Fascoe 6.' e//ev April 28, 1953 R. G. GELLER PLATFORM SUPPORTING MECHANISM 2 SHEETS-SHEET 2 Filed July 18. 1947 INVENTOR Zf'orrae 6.' 'e//er W?" ATTORNEYS Patented Apr. 28, V1953 UNITED STATES PATENT OFFICE 7 Claims.

This invention relates to foldable platformsupporting mechanism wherein the platform may consist of a chair seat, table, ironing board or the like, and wherein such a platform is to be supported in part from' a wall or other structural member disposed in a vertical plane, and in part by a leg structure pivoted to the platform and extending downward into contact with the oor when the platform is in use.

The principal object of the invention is to provide a foldable platform-supporting mechanism of the character described which, when permanently attached to a vertically disposed wall, partition, door or the like, will firmly support the platform at its forward and rearward edges and will still be readily foldable against the wall or other fixed structure when not in use.

Another object is to provide a folding mechanism' whereby the platform with its forwardly located supporting leg structure may first be raised at its rear edge and thereafter placed in substantially vertical position parallel to the fixed structure to which it is attached.

The invention is particularly advantageous for supporting chair seats attached to the walls or partitions of kitchenettes, restaurant booths, or in other restricted spaces. Another useful application is the attachment of a chair seat to a bathroom wall or door. Still others are to support table tops and ironing boards.

The embodiment of the invention selected for illustration is for supporting a chair seat, and it will be understood that the chair seat is merely illustrative of any desired platform.

In the accompanying drawings,

Figure 1 is a side elevation showing a folding seat constructed in accordance with this invention, and showing in dot-and-dash lines the positions occupied by the parts during folding of the seat,

Figure 2 is a view similar to Figure l but showing the seat and supporting mechanism in their folded positions.

. Figure 3 is a rearward view of the seat tak-en on the line 3-3 of Figure 2, with most of the partition broken away.

The folding seat comprises a platform III covered withupholstery II and pivotally connected at'its forward end to a leg structure I2. The leg structure I2 includes a foot portion I3 which rests on the floor I4 when the folding seat is in position to be used, as shown in full lines in Figure 1. In the preferred construction illustrated, the leg structure I2 comprises two legs connected to opposite sides of the platform I0, as shown in Figure y3, but it will be understood that the invention can be made with a single central leg.

The folding seat is connected with a vertical partition or wall I5 by frames I6. These frames I6 are angle irons, in the construction illustrated and have openings I8 for screws, or other fastening means, that secure the frames to the wall or partition I5.

Two links 2| and 22 are connected with each of the frames I6 by pivots a and b. Each link 2| is connected with a lug 24 on the leg structure I2 by a forward guide or control link 23. This guide link 23 is connected with the link 2| by a pivot c and with the link 22 by a pivot d. These pivots are referred to by letters to facilitate the subsequent description of the folding linkages.l If the links 2| and 22 are pivotally connected to lugs on the partition I 5 without a frame I6, then the partition comprises the frame connecting the pivots a and b.

The forward end of each link 2| is connected with a lug 26, extending down from the platform I0, by a pivot connection e. The pivot connection of the platform I0 with the leg structure i2 is indicated by the reference character f, and the pivot joining each link 23 with the leg structure I2 is indicated by the reference character pv.

links 2|. If a somewhat deeper seat is used, the'v platform l0 will rest on the frames I6, if these frames are as high as the rearward top portion of the link 2 I When the seat is to be moved into its folded position, the rearward end of the platform It is lifted and the parts are moved into the substantially vertical positions shown in Figure 2. In order to facilitate the lifting of the rearward end of the platform IIJ it is desirable that this platform terminate sufficiently far in front of the partition I5 to permit a person to put his hand down behind the platform to raise it.

Certain correlations of the links and the distances between the pivots are necessary in order to have the structure fold into the compact relationship shown in Figure 2. One relationship is that the different links be in different vertical planes, as is clearly illustrated in Figure 3, and another relationship is that the combined lengths of certain links be equal.

The links will be referred to by their effective lengths in considering folding and motion of the parts. The effective length in each case is the distance between the pivot points of a link, and the links will be indicated by reference to `their pivots. For example, the folding mechanism includes two four bar linkages. One comprises the stationary link ab, and `the movable links' ac,

ed, and db. The other four bar linkage comthe floor as soon as the folding motion is begun.

Many prior folding constructions have leg structures that drag across the floor for some distance before lifting, or that move downward during the first part of the folding motion. Structures that drag across the floor are objectionable because they do not fold as easily and after some use leave the noor in a damaged condition. Folding mechanisms that must move downward during the rst part of the folding operation cannot be used for connection with a wall or other fixed partition, .but are only suitable for chairs or similar devices that can be lifted to permit the relative downward movement of the leg structure.

As the mechanism is folded, the link 23 swings counterclockwise about the pivot c and thus the pivot g swings downward with respect to the pivot c. In order to prevent the leg structure l2 from moving downward, it is desirable that the vertical component of movement of the pivot c be more rapid than the vertical component of the downward swinging movement of the pivot y with respect to the pivot c.

Some compensation can be obtained because of the fact that the leg structure l2 swings somewhat to the right during the first part of the folding movement. Since the leg structure is originally in a substantially vertical position, this initial swinging movement toward the right tends toraise the bottom of the leg structure i2. With a leg structure that occupies a vertical position when in use, it is desirable to have the leg structure rise, however, without relying upon its angular movement to lift the lower end of the leg structure clear of the floor, because the initial swinging movement of the leg structure I2 from a substantially vertical position has no Vertical component.

In making the folding mechanism to obtain a rising movement for the pivot c greater than the downward movement of the pivot g, it is necessary to correlate both the link lengths and the angles of the linkage. For example, the distance that the pivot c moves upward, during any increment of time while folding the mechanism,`is equal to the length of the link ac multiplied by the difference between the sines of the angles that this link makes with a horizontal plane through the axisof the pivot a at the beginning and end of the time increment. On the other hand, the distance that the pivot g moves downward with respect to av horizontal plane through the axis of the pivot c, during the same increment of time, is` equal to the length of the link cg multiplied by the difference between the sines of the angles that this link cg makes with the horizontal plane through the axis of pivot c at the beginning and end of the time increment.

Expressing this relation in another way, the rate of change of the value ce sine A must be greater than the rate of change of the value cg sine C where A is the angle between the-link ac andy the horizontal plane through the axis of Divot a; and C is the angle between the link vcg 4 and the horizontal plane through the axis of the pivot c.

It will be evident that the mechanism can be designed to make the leg structure i2 rise from the door more rapidly by moving the pivot d away from the pivot c and closer to the pivot y. This reduces the rate at which the angle C changes. Such a change in the linkage, however, requires an increase in the length of the link ab in order to maintain the quality ab plus ce equals cd plus bd. The links cd and cg can be coincident.

The structure comprises a rearward four-bar linkage abrio, which swings about the xed pivots d and b. Another four-bar linkage fecg is connected to the rearward four-bar linkage by the pivots c and d. The manner in which the structure folds depends upon the restrictions imposed upon the movement of the forward linkage by the rearward linkage; and more specifically upon the restrictions imposed upon the movement of' the link cg by the links ae and bd.

It is evident that the link cg swings counterclockwise about the pivot d as the structure folds, and the pivot d swings about the pivot b in a clockwise direction. Therefore, the absolute movement of point g depends upon its relative movement about d as a center and upon the movement of d about the fixed center b.

The extent to which one of these movements counteracts the other depends upon the angle that the links cg and bd make with one another and upon the relative distances of the points C and g from the center d, and upon some other factors.

In analyzing the movement and the relationships necessary to prevent the point g from moving downward as the structure begins to fold, the. following symbols will be used:

Vg=absolute velocity of g- Vg (vert.) :the component in a vertical direction of the absolute velocity of g Vg (vert. and rel. to d) :the vertical component of the velocity of g with respect to d' Vd=absolute velocity of d Vd (vert.) :the component in a Vertical direction of the absolute velocity of d Vd (vert. and rel. to c) :the vertical component of the velocity of d relativeto c Vd (link cd) :the component in the direction cd,l

of the absolute velocity of d Vc=absolute velocity of c Vc (vert.) :the component in a vertical direction of the absolute velocity of c Vc (vert. and rel. to d) :the vertical componenti of the velocity of c with respectto d Vc (link cd) :the component in the direction cd of the absolute velocity of c Angle L=the angle between the vertical and the instantaneous direction of movementv of d as it rotates about b. This angle is also equa-l' to the angle that the link bdA makes with thefhorizontal (i. e. :r axis) Angle M :the angle between the link cg and the instantaneous direction of movement' of, d, about the center b; this angle M is the complement of the angle adb;

Angle N :the angle between the vertical and the` instantaneous direction of movement of point4 c about the center a; this angle N` is. also equal to the angle that the link ac makes with the horizontal and is equal to zero at the begin.- ning of the folding movementv in the-construe,- tion. l

assaut);

Angle O=the angle between the link cg (eX- tended) and the instantaneous direction of movement of the point c about center a; this angle O is also the complement of the acute angle between the links ac and cg (extended).

Vd (vert.)=Vd cos L (l) Vd (link cd)=Vd cos M (2) Vc (link cd)=Vd (link cd) :Vd cos M (3) :Vc (link cd)=Vd cos M (4) Vc cos O cos Vc (vert.) =Vc cos N Substituting Equation 4 in Equation 5:

Vd cos M Vc (wert.)-cosN(-c-6ST cd l Thus the longer the lever arm dg is with respect to the arm cd, the more the point g will move for any given movement of the point c. This relation may be expressed by saying that the downward component of movement of point g resulting from swinging of the link This is an interim equation not considering the velocity of point d.

When the velocity of point d is considered.

there is a liftingiof the link cg. Since the effect of movement of the point c has already been considered, the motion of point d above may now be considered and the lift of the point g will depend upon relative lengths of lever arms. The upward component of movement of the point g caused by lifting of the link by point dis equal to the rise' of the point d multiplied by the ratio of the lever arms This may be expressed by the interim equation.

Upward component of point g -cdVd (vert.)

This can be expressed in the equation as follows:

Substituting values from Equations 6 and 1 in Equation '7 above: Y.

cos 0 Equation 8 can be simplified as follows:

dg cosN cos M=or cg cos O cos L (9) From this a relation of angles to the location of the pivot d can be obtained as follows:

cos L cos 0 I` cos N cos M (lo) Figure 3 shows a construction in which the platforml0 includes two parallel frames 28 connected with the separate frames I6 by independent sets of duplicate linkages. The mechanism can also be made with a single set of heavier linkages located approximately at the center of the platform, and it should be understood that a single set of linkages can be used with either a single leg structure or with the double leg structure shown in the drawing; and likewise a single leg structure can be used with the duplicate sets of linkages. Terms of orientation are, of course, relative. y

- The preferred embodiment and some modications of the invention have been illustrated and described, but various other modifications and changes can be made, and some features can be used alone or in different combinations without departing from the invention as described in the claims.

f What is claimed is:

f 1. The combination comprising a platform, folding mechanism supporting the platform, said mechanism comprising a leg structure pivotally connected to the platform for supporting one end of the platform from the fioor, a first linkpivotally connected at one end with the platform and having a pivot at its other end that connects with a fixed location on a wallor partition and at a level at least as low as the connection between the link and platform, a second link connecting the leg structure with the first link intermediate the endsof the first link, and a third link connected at one end with the second link at a region intermediate the ends of the second link and having a pivot that connects the-other end with the Vertical wall or partition at a location below the pivot connection between the first link and the Vertical wall or partition, the lengths and angular relation of said links with respect to one another being constructed and arranged to lift the leg structure off the floor as the links begin to fold.

2. Folding supporting mechanism for a platform that has a leg structure pivotally connected to it, said mechanism including a first link that connects a mid-portion of the platform with a fixed support and oriented to swing upward about its connection with the fixed support-during folding movement, a second link connected at one end with the first link, intermediate the'ends of the first link, and connected at the other end with the leg structure and oriented to swing downward with respect to its connection with the first link during folding of the mechanism, and other link means that are connected with v the fixed support and pivotally connected with the other parts of the supporting mechanism, the link lengths and angularity of the links of the folding mechanism with respect to one another being constructed and arranged to cause the connection between the first and second links to move upward at a faster rate than the other end of the second link moves downward with respect to saidv connection during at least the initial stages of the folding movement.

3. The combination of a platform, a leg structure pivotally connected with the forward end of the platform, a first four bar linkage including a portion of the length of the platform as one of the links, and a portionof the length of the leg structure as another one of the links, a frame for connection to a vertical partition, and a second four bar linkage connected with the first four bar linkage at two spaced regions, one of which is intermediate the ends of a. rearward link of the sesam first four bar linkage, said" second four bar link-V age including at least a portion ofthe length of the frame as one of the links, the horizontal extent of the second four bar linkage being substantially greater than; that of said first four bar linkage when the platorzn is disposed in a horizontal position, and the link lengths of the sccondfour bar linkage and their angular relation to'one another and to a 'rearward link of the first four bar linkage being constructed and arranged to lift the rst four bar linkage" and the leg striki-l ture at the start of an upward folding of said second four bar linkage.

4. A platform movable between a substantially horizontal position and an upwardly extending folded position, a legrv structure plvotally connectedto the forward end ofthe platform, an up-V per link connected at one end with an intermediate point of theV platform and at the other end with a fixed support, a forward link shortertha'n said upper link and connected at one end-to the leg structure and at its other end to the upper link at a region intermediate the ends oftheupper link, and a lower link pivotally connectedv at one end to the fixed support at a fixed location below the upper link, said lower link extending forwardly and upwardly and having its forward end pivotally connected to the forward link intermediate the ends of the forward link and at' a substantial distance from the upper endl of the forward' link, said distance, the link lengths andy the angular'ity of the upper, lower and forward links withrespect toene another being construct'- ed` and arranged to give' the leg structure an` up'- ward component of movement from the beginning of the folding movementof the links.

5. A folding supporting mechanism for a platform, said mechanism comprising' a leg` structure pivotally connected' with the forward end of the platform, an upper link connected at one end toan intermediate point of the platform and pivotally connected at its other endI with a xed support at the rearward end of the mechanism, a second link shorter than the upper link and connected at its forward end with the leg struc-v ture andA sloping upwardly and rearwardly ataninclination to the horizontal and to the upperv link, a pivot connecting therearward end of the secI ond link with a point intermediate the ends ofthe upper link and spaced from the connection of theiixed support' and upper link by a distance greater thanthe effective length of said second' link, and a third link connected at one end to 'an' intermediate point" of the second link and pir#k otally connected at its other end with the fixed support at aregion below the connection of the' upper link and therlned` support.

c. A foidabre platformsupport for attachment to a wall structure'dsposedpermanently'in a sub stantially vertical plane, comprising, in combina'-y tion, two parallel frame members for nxed attachment to the wall structure, a platforrri mein--` ward ends with the underside of the platform member, a second pair of identical links plv-l otally connected atv their forward ends withthek leg structure and pivotally connected at their rearward ends with the first pair of links at a level higher than their pivot connections to the leg structure, a. thirdpair' of identical links pivotally connected at their forward ends with the second pair of links and pivotally connected at their rearward ends with the frame members, the lengths of the several pairs of links and their respective points of attachment being constructed and arranged so that the upward movement of that portion of the platform member which is adjacent to the frame members causes the lower extremity of the leg structure to move upwardly and toward the frame members as the forward end of the platform ispushed rearwardly.

'7. The combination comprising a platform and a leg structure pivotally connected to the forward end of the platform, an upper link pivotally connected with the platform at a substantial distance behind the leg structure, a bearing' at the rearward end of the upper link for pivotally conmeeting said upper link with a fixed and vertically extending support, a second link extending downwardly and forwardly and which is pivotally connected at its upper end to the upper link intermediate the ends of said upper link and pivotally connected at its lower endr to the leg structure, a lower link connected to the second link intermediate the ends of the second.v link and extending rearwardly and downwardly at an acute angle to the upper link, a bearing at the rearward end of the lower link for pivotally connecting the lower link with the xed and vertically extending support to which the rearward end of the upper link connects, the angular relation of the links being suchthat cos L cos 0 cos N cos M is at least equal to where L isv the angle of the lower linkv with the horizontal', N is the angle of the upper link with the' horizontal, O is the complement of the acute angle between the upper link and the second link andM is the' complement of the acute angle between the second link and lower link and the ratio is the ratio of the distance of the pivotal connection between the second link and the lower link from the-lower endof the second link to the total length ofthe second link.

ROSCOE G. GELLER.

References Cited in the iile of this patent lUNI'FED SJJII'ISl PATENTS Number Name Date 1,765,168 Laursen June 17, 1930 1,981,387 Kovats Nov. 20, 1934 2,044,473 Geller June 16, 1936 2,308,496 Deffenbach Jan. 19, 1943 FOREIGN PATENTS Number Country Date 4,592' Great Britain Dec. 2, 1915 163,634 Great Britain 1..-- May 26, 1921 398.498 France Mar. 24, 1909

Images