US 2195241 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Gttornug' March 26, 1940- R. A. CRAMER ET AL POSTURE CHAIR Original Filed Nov. 22, 1937 Z W W s k r m Patented Mar. 26, 1940 PATENT OFFICE POSTUBE CHAIR Roy A. Cramer and Jesse F. Cramer, Kansas ty, Mo.
Application November 22, 1937, Serial No. 175,766 Renewed February 2, 1940 6 Claims. (c1. 155-151) This invention relates to posture chairs and has for its general object to produce a back support of usual type in such chairs, such as shown in our Patent No. 2,054,557, issued September 15,
1936, but which, in addition, has its' back support pivoted so that the occupant may lean back and secure a restful rocking position when desired. This result is secured by maintaining substantial equilibrium at any point throughout 10 the range of rocking movement so that the occupant need exert no force in either direction to maintain balance.
Another object of the invention is to produce a spring back which not only progressively increases its resistance to increasing load of the body weight as the chair back recedes from the vertical as in the usual arrangement having helical springs, but also one in which the initial resistance of the spring to movement from posture position is great to avoid accidental recession of the back from posture position, this construction being claimed in our copending application Serial No. 270,982, filed May 1, 1939. After the occupant forcibly pushes or trips the back beyond posture position, the tension arrangement is such that for its range of rocking movement, the parts are in substantial equilibrium up until the chair has almost reached its limit of rocking movement, when the resistance to backward movement of the chair back increases more rapidly than the shift in the center of gravity of the body weight, thus avoiding the possibility that the occupant will unintentionally swing the chair back to its fixed stop with the abrupt blow now common with the ordinary type of spring mounting. In other words, with the chair of the invention, it takes a decided effort by the operator, greater than mere body weight, to start the chair back from posture position, the chair back then has a range of movement in which thespring may be adjusted to balance increased body weight, and finally before the fixed stop is reached, the tension of the spring is increased more than is necessary to balance body weight,
making it necessary for the occupant to exert an additional force before the back of the chair can be forced back its full course of travel.
Another object of the invention is to provide a pivoted or rocking back for chairs, of such nature that the back may be adjusted toward and from the seat in a straight line by a sliding movement without rocking the back or changing the relation between horizontal planes passing through the seat and back, whereby the chair can be adjusted for tall or short occupants without changing the tension resisting rearward tilting of the back as more particularly claimed in our copending application Serial No. 270,982, filed May 1, 1939.
A further object of the invention is to produce a resilient cushion or chainseat having a flexible covering member secured in position against shifting under the flexing of the seat or cushion due to body movements when the chair is in use, as more particularly claimed in our copenda Eng1 9arzplication Serial No. 302,198, filed October With the general objects named in view and others as will hereinafter appear, the invention consists in certain novel and useful features of 1 construction and organization of parts as hereinafter described and claimed; and in order that it may be fully understood, reference is to be had to the accompanying drawing; in which:
Figure 1 is a side elevation of a chair embodying the invention.
Figure 2 is an enlarged fragmental side elevation, partly in section to illustrate the ten-' siorling device for the pivoted chair back suppor Figure 3 is an inverted plan view of the chair seat or cushion to illustrate the method of securing the flexible cover to the cushion.
Figure 4 is a plan view of the spider supporting construction, the seat having been removed.
Figures 5 and 6 are respectively bottom plan and edge views of a cushion embodying certain features of the cushion shown in Figure 2.
In the said drawing, where like reference characters identify corresponding parts in all of u the figures, the supporting pedestal structure will not be described in detail since it is shown in our aforesaid Patent No. 2,054,557, other than to point out that the upper ends of the legs I where welded to the spindle supporting casing 2, 40 are preferably enclosed in a housing member 3 which reinforces and braces the legs and adds a more finished appearance to the chair. Pivotally mounted on the upper end of the spindle 4 is a spider 5 to support the seat. Although this spider may be as shown in our previous pat ent, we have found that it is desirable to have the spring pressed locking pin 6 rearwardly of the spindle instead of forwardly thereof as shown 5 in our previous patent, since it makes it possible to secure the same range of adjustment of the back toward and from the seat with a shorter horizontally adjustable supporting bar I slidingly mounted in a channelled portion Ia of the spider ,tally adjustable support instead of being upstanding to form a back support or standard as in our previous patent, terminates in a downwardly and forwardly curved portion 9, which is preferably of spring or resilient nature. Secured to the end of the curved portion 8, which preferably terminates substantially parallel to, but underlying the main body of the member I, is an upstanding square tube III slidingly but non-rotatably receiving a squared stem II equipped at its lower end with a journaled anti-friction roller member I 2. When the parts are assembled as hereinafter described, the roller I2 cannot fall from position, but the parts may be provided with a locking pin to prevent disengagement if thought desirable. The upper end of the rectangular tube I8 is closed by a plug Illa, the latter being threaded for engagement with adjusting bolt I3 having a hand wheel I4. The bolt I3 is unconnected with, but is adapted to press against, the end of the non-rotatable stem I I, and it will be apparent that by adjusting the hand wheel, the bolt I3 will project the stem II carry-. ing the roller I2 for tensioning purposes as will hereinafter appear.
Welded or otherwise secured to the bar mem ber I forwardly of its resilient portion 9 is a fixed block member I5. Embracing the downwardly curved spring end of the bar I, but spaced therefrom, is a yoke member I6 which is provided with a pivot pin mounting I'I journaled in the fixed block I5. The closed end of the yoke fixedly carries an upright standard or back member I8, the latter at its upper end carrying a vertically and tiltably adjustable back rest I9, such as shown in our patent aforesaid. The lower end of the back member I8 is bent forwardly to form a cam surface or track I'Ba, it being understood in this connection that the cam or track member, although preferably of resilient or spring nature, can be unyielding, the entire resiliency being in the member 9. In other words, either one of the members 9 or I9a may be resilient, or both may be resilient as shown, without changing the operation of the chair. The cam member I9a is adapted to be in constant contact with the roller I2, and it will be apparent that by adjusting the hand wheel I4, the tension on members 9 and I9a, and consequently the pressure on the back support to be overcome by the body weight of the occupant, may be set at the desired limit. Thus, by regulating the distance between the ends of members 8 and I9a, through the operation of the tensioning means (the hand wheel I4, bolt I3, and roller I2), the force resisting rearward rocking or swinging of the back member I8, may be adjusted. Stop means must be provided to limit the forward and rearward swinging of the back member. To limit forward movement, the front lower corner of the yoke I6 carries a cross pin 20, which, by contact with one side of the U-spring member 9, prevents the back member I8 from being thrown forwardly of a substantially vertical position, as shown in Figures 1 and 2. To reinforce the yoke I8 its rear lower corner is strengthened by a cross pin 2| which also acts to limit rearward swinging movement of the back member I8, since as the yoke I6 and the back member rigidly secured thereto, swing around the axis of the pivot bolt I1, the cross pin 28 moves away from the spring member 8 while the cross pin 2| approaches the opposite side of said spring member; and when contact occurs between members 8 and 2| further swinging movement of the back member is prevented as there is no resiliency in the small length of the member 9 between the point of contact of cross pin 2| .and the pivotal point I1.
It has been found that by forming a depressed portion 22 in the front end of the cam track Isa (see Figure 2), corresponding to posture or upright position of the back standard, considerable resistance is offered to' recession of the chair back, this resistance, of course, being subject to manual adjustment by the hand wheel I4. After the chair back has passed rearwardly of posture position, it will be evident by consideration of the dotted arc a-a, struck from the center of rotation, the axis of the pin I1, Figure 2, that the curvature of the cam track I8w as it moves past the roller l2, will entirely control the degree of tension of the members at any predetermined angle of tilt of the back member of the chair. In helical spring back chairs, the tension of the spring is practicallyalways in direct proportion to the extent of swinging movement, but with our cam track arrangement it will be apparent that the curvature of the track can be such as to give any desired rate of increase in tension.
As previously mentioned, the chair seat is preferably of sponge rubber or the like, and by preference, the chair bottom or base plate 23 is provided with a multiplicity of openings 24 to permit of ready entrance and exit of air to the interstices in the cushion. To hold the cushion in proper position, it is usually glued, and in addition, it is preferably to form the side margin of the base plate with an upturned flange 25 which snugly embraces the edge of the cushion. The cushion is then completely covered by a flexible fabric 28, the side edge of the cover underlying the base plate and being hemmed to receive a draw cord 21 underlying the base plate. To hold the cover in proper position and under tension, one end of the draw cord is secured to one of a series of downwardly extending ears 28 constituting limiting abutments for the draw cord, said ears projecting from the base plate 23, and spaced inwardly from the margin of the seat. The other end of the draw cord is provided with a resilient spring terminal 29 engaged with one of the ears 28 to effect the return of the seat cover to proper position if it is pulled to one side or the other under the pressure of the seat occupan In Figures 5 and 6, the cushion member is shown as comprising a pad of resilient rubber 30. The rubber pad is covered by a fabric covering 3| having its edge tubular to receive a flexible cord 32 by means of which the cover is stretched smoothly and underlies themarginal edge of the pad. To prevent the bottom edge of the seat cover from being pulled from the position shown in Figure 5 at any side of the seat, a series of tapes 38 are stitched to opposite edges of the cover. Strain tending to pull one side of the cover is thereby transmitted to an opposing side or portion of the cover.
From the above description it will be apparent that we have produced a chair and cushion embodying all the features of advantage set forth as desirable, and while we have described and illustrated the preferred embodiment, it is to be understood that. we reserve the right to all changes within the spirit of the invention and without the ambit of the prior art.
1. In a chair, a seat support, a supporting member secured to the rear of the seat support and having a rearward and downwardly curved resilient extension, a tensioning device on the end of the extension, a back member pivotally connected with the supporting member, said back member having a lower cam-like resilient extension of gradually increasing curvature slidably engaging the end of the tensioning device, whereby the spring tension on the supporting member extension and on the cam-like extension is increased as the back member is swung rearwardly.
2. In a chair, a seat support, a supporting member secured to the rear of the seat support and having a rearward and downwardly curved resilient extension, a tensioning device on the end oi! the extension, a back member pivotally connected with the supporting member, said back member having a lower cam-like extension of gradually increasing curvature slidably engaging the end of the tensioning device, whereby the spring tension on the supporting member extension is increased as the back member is swung rearwardly.
3. In a chair, a seat support, a supporting member secured to the rear of the seat support and having a downwardly curved extension, a tensioning device on the end of the extension, a back member pivotally connected with the supporting member, said back member having a lower cam-like resilient extension of gradually increasing curvature slidably engaging the end of the tensioning device, whereby the spring tension on the cam-like extension is increased as the back member is swung rearwardly.
4. In a chair, a seat support, a seat carried by said seat support, a back supporting member carried by the seat support, a back member pivotally connected to the back supporting member, said back supporting and back members each having an extension, one of said extensions being resilient, and a tensioning device carried at one of its ends by one of said extensions, said tensioning device having its opposite end abutting against the other extension, said extensions being so shaped that the force imposed by the resilient extension tends to pivot the back member forwardiy toward the seat when the back member is tilted rearwardly.
5. In a chair, a seat support, a seat carried by said seat support, a back supporting member carried by said seat support, a back member pivotally connected to said back supporting member and provided with an extension, a leaf spring projecting from the back supporting member, and a tensioning device carried by said leaf spring and abutting the extension, the shape of the extension being such that the distance from the pivotal point of the back member to the point of contact of the tensioning device on the extension gradually decreases on rearward pivotal movement of the back member to increase the tension on said leaf spring.
6. In a chair, a seat support, a seat carried by the seat support, a back supporting member carried by the seat support, said back supporting member being mounted on the seat support for relative back and forth horizontal adjustment with respect to the seat, a back member pivotally connected to the back supporting member, a back rest carried by the back member, tensioned resilient means between the back member and back supporting member resisting rearward pivotal movement of the back member when force is imposed on the back rest, the tension imposed on said resilient means being unaffected by the back and forth horizontal adjustment of the back supporting member with respect to the seat, and manually operable mechanism for adjustably regulating the tension imposed on said resilient means.
ROY A. CRAMER. JESSE F. CRAMER.