WO2005055908A2

WO2005055908A2 - Quarternary spring suspension

Info

Publication number: WO2005055908A2
Application number: PCT/US2004/040255
Authority: WO
Inventors: Sam Conte
Original assignee: J. Robert Britton & Associates, Inc.
Priority date: 2003-12-02
Filing date: 2004-12-02
Publication date: 2005-06-23
Also published as: WO2005055908A3

Abstract

A recliner (80) includes an outside housing (82), a pivotable support assembly (84), and a seat (86). The outside housing (82) includes a right arm and a left arm. The pivotable support assembly (84) is pivotable mounted between the right arm and the left arm. The pivotably support assembly (84) is configured for facilitating a selectable reclining action. The seat is mounted on the pivotable support assembly. The seat includes a quaternary spring support system (45) therein, the quaternary spring support system (45) being configured for facilitating a selectable rocking action of the seat. The quaternary spring support system (45) includes a primary, U-shaped leaf spring having a to pair of extensions (each of which are capable of acting as a spring) and further includes spaced-apart first and second resilient members. Each resilient member is fixed to one of the extensions and is engageable with the other extension.

Description

QUATERNARY SPRING SUSPENSION BACKGROUND OF THE INVENTION 1. Field of the invention. The present invention relates to chairs and more particularly, patient chairs as 5 used, for example, in health care facilities. 2. Description of the related art. Patient or health care chairs are commonly used in hospital rooms, assisted living homes, waiting rooms, hospices, extended care facilities, and at home. Health care chairs are used primarily, but not exclusively, by persons who have difficulty0 rocking or reclining in commonly available rockers and/or recliners. An additional complication with the latter chairs is, a health care requiring person may have difficulty in entering, sitting, or egressing that chair. Further, such chairs do not automatically compensate for the user's mass. There are many recliners and rocker type chairs on the current market and5 used in health care applications. Most of these recliners, and rockers, require some type of physical effort to make the chair rock or recline, that is by pulling on levers, pushing buttons, or using the force of legs onto a leg panel, or the human back pressing onto a chair's back-rest, to make it recline. All or any one of these physical efforts, i.e. motion, may not be possible for a sitting person who is recovering from o surgery, age enfeebled or obese. The latter persons usually cannot lean down to grab a handle, or a post surgery person is unable or restricted from use of arm, chest, or back muscles. There are also powered chairs which are motor driven between a seated or reclining position and a forward upright position which aids ingress and egress. These powered chairs are relatively large, heavy and expensive, and not well5 suited to use in health care facilities. Health care patient chairs typically have only two primary legs integral with and extending upward at the front of the chair from a sled type base. This type of structure possesses a significant degree of instability. The seat of this type of chair is supported by, and on, or cantilevered directly off of the front legs. This type of construction is inherently unstable for a person who may need to sit by impacting the seat, or otherwise falls into the seat due to disability. This type of impact could cause the entire chair to "skitter" backwards, away from the entering person, causing them to lose balance and fall. This type of action could impose a force upon the chair that would have force vector components that are substantially perpendicular to the support, the front legs, and be of a sufficient magnitude to result in upsetting the chair from its normal upright position. The seat of the typical patient chair has no structural connection to or support directly from the rear legs, if any, of the chair, thus adding to the instability of the chair. The arm supports of typical patient chairs are supported only by the vertical extension of the front legs of the chair. The arm supports lack any structural connection to or support directly from the rear legs, if any, of the chair. Thus, even further instability is added to the typical patient chair. A weakened patient attempting to sit down in the typical patient chair will naturally use the arm supports to assist in maintaining balance and to enable a gradual entry into the chair. In so doing, a patient will impose a force which is, at any one moment in time, composed of vertical and horizontal vector components. In an unsteady patient, the magnitudes of those horizontal and vertical vector components will vary significantly over a very brief period of time. The typical patient chair, with arm supports lacking, connection to or support from the rear legs, if any, will become unstable when the sum of those horizontal and vertical vector components of the force applied by the patient is of a direction and magnitude which is not substantially and directly aligned with the support structure of the chair. The front edge of the seat of the typical patient chair is positioned in line with the front legs, thereby making it difficult for an unsteady patient to place his feet and legs in a position and orientation that will enable sitting or standing. Furthermore, the arm supports of the typical patient chair do not extend substantially in front of the front edge of the seat, thereby increasing the difficulty encountered by an unsteady patient attempting to position their body in preparation for ingress or egress. Some patient chairs provide a rocking motion. However, the rocking motion provided often forces the feet of the patient seated in the chair to lose contact with the floor, thus placing a degree of pressure on the back of the thigh of the patient's legs. Such pressure can severely restrict or cut off the circulation in a patient's lower legs. Furthermore, the rocking motion provided by some patient chairs is relatively undamped. An undamped rocking motion can cause an excited state in patients, particularly patients recovering from heart surgery and Alzheimer's. Patient chairs typically have either all wood frames, or frames composed of wood and metal, which are mechanically fastened together. With continued use of a patient chair such mechanical fasteners are prone to loosen. Further, most prior art chairs with springs have only a single spring constant available for use. What is needed in the art is a patient chair which remains stable during a patient's ingress and egress, reduces the difficulty of ingress and egress, and provides a self-damped rocking, motion. SUMMARY OF THE INVENTION This invention provides a health care patient chair having a pair of arm supports extending forward of the seat, a seat positioned substantially rearward of the front legs. The present invention further provides a stable, self-damping, rocking motion, and a limited recline sitting position. Chair use is, of course, not limited to the infirmed. The invention comprises, in one form thereof, a chair having a seat, a backrest, a support pedestal adapted to rest on a floor or other horizontal support surface, and a pair of U-shaped compound springs coupling the seat and backrest to the pedestal. Each spring has an upper longer portion, a lower shorter portion extending generally horizontally and parallel to the longer portion, and a bight or U-shaped end coupling the shorter and longer portions together. The shorter portion is fastened to the support pedestal between the shorter portion free end and the bight. The seat is fastened to the longer portion between the bight and longer portion free end, and the backrest is fastened to the longer portion free end. A pair of resilient pads are fixed to each spring shorter portion, engage the longer portion when the spring is compressed by a chair occupant and contribute to the overall spring action. The quaternary spring motion and/or system created, to be later identified simply as Q4, is separately operable in various styles of sitting equipment (e.g., chairs, sofas, loveseats) and includes the ability to be dropped into various types of housings. An advantage of the present invention is that the structure and configurations of the chair inhibit continued, volunteer oscillation since the system is self damped, yet provides a stable rocking motion. Another advantage is that the structure and configuration of the chair prevent movement as a result of the forces applied by a person during the process of sitting in or standing up (egressing) from the chair. A further advantage of the present invention is that the suspension senses the size and weight of the sitting, person and reacts and compensates to these attributes, and/or limitations. An additional advantage is that the suspension of this inventions does not require external actuating levers, buttons, or manually activated mechanisms to achieve rocking or reclining motion. BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of various embodiments of the invention taken in conjunction with the accompanying drawings, wherein: Fig. 1 is a perspective view of the basic chair components of leg frame, mesh seat, backrest and removable arms used in one embodiment of the present invention; Fig. 2 is a more detailed perspective view of the chair suspension components used in the chair shown in Fig. 1 ; Figs. 3a-3e are side elevation views of progressive development of the quaternary (Q4) spring system of the present invention; Fig. 4 is an exploded perspective view showing all the components of the basic chair of Fig. 1 ; Fig. 5 is a graph of load vs. deflection for an illustrative Q4 spring system of the present invention; Fig. 6 is an exploded view of a recliner employing the Q4 spring system of Figs. 3a-3e; Fig. 7 is a view of a prior art rocking motion on a classical rocking chair; Fig. 8 is a view of rocking motion in a prior art glider style rocker; Fig. 9 is a schematic view of a chair employing the Q4 assembly, showing the constraints of rocker movement now found desirable to solve the problem in the art; and Figs. 10 and 1 show additional details of the Q4 assembly disposed within a recliner chair. Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one preferred embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings and particularly to Figs. 1 and 4, there is shown a patient chair 12 having support pedestal 22 comprising two front legs 14 and 16, two rear legs 18 and 20, and a pair of side members 24 and 26. A rear frame member 28 connects the two rear legs 18 and 20. A cross member 30 connects the side members 24 and 26 intermediate the front and rear legs at a position substantially rearward of the front legs 14 and 16. Two configured leaf springs 32 and 34 are attached to the bottom of the cross member 30, for example, by screws such as 36, and thereafter extend rearwardly in a substantially horizontal manner. Comparing Figs. 2 and 3, the front of the leaf spring extends forward of the cross member 30, but terminates rearward of the front legs 14 and 16, curves substantially downward and loops rearwardly passing under the cross member. The leaf spring attaches to the cross member as it passes thereunder, then the leaf spring continues rearwardly for a short distance or extension 38 (Fig. 3b), past the cross member, under and parallel to the leaf spring upper, longer top layer 60. The seat 40 is connected to and supported by the leaf springs 32 and 34. The seat may be formed of a flexible, porous fabric sewn into a hammock shape and disposed between the two primary seat springs. This hammock shape and flexible, porous fabric allow the springs to act in harmony with each other, creating a continuously flexible seat. The front edge of the seat bottom is positioned rearwardly of the front of the front legs 14 and 16. A compression spring medium such as an elastomeric spring mass 42 is attached to the topside of the cross member 30 under each leaf spring top layer, at the point where each leaf spring, passes over the cross member 30. A second compression spring such as 44 is attached to the bottom rearward facing projection such as 38 of each leaf spring and touches the underside of the leaf spring top layer. Two arm supports 46 and 48 are positioned above the seat and extend substantially forward of the front edge of the seat 40. The armrests or supports have reduced diameter sections such as 52 which are telescopically inserted into and supported by the open tops of the rear legs 18 and 20. A rigid molded wood backrest 50 is connected to and supported by the leaf springs and terminates the ends of the two primary springs 32 and 34 by attachment to these springs in a substantially vertical position. The backrest is attached by screws such as 68. This backrest has flexibility limited by its cantilever position at the terminus of the primary spring. Each of the rear legs 18 and 20 is angled forward upwardly toward the seat. Decorative and/or protective caps such as 70, 76 and 78 may be inserted into or over the upper open arm and leg ends, and floor engaging feet such as 72 may be inserted into or over the open lower leg ends. Primary leaf springs 32 and 34, secondary springs 42, and trinary springs 44

(Figs. 3a-3e) together define a quaternary (Q4) spring support system 45 within a seat 40. In Fig. 3a, primary leaf spring 32 is attached to cross bar 30 by bolt 36. An upper extension of leaf spring 32 provides the primary spring system, a cantilevered leaf spring. In Fig. 3b, secondary spring 42 is fixed to the cross bar 30, also by the bolt 36. (It is noted that bolts 36 could be replaced with any other suitable attachment means including weldments.) In Fig. 3c, trinary spring 44 is fastened to the lower extension 38 of leaf spring 32 by screw 54. Fig. 3e illustrates a reverse (counterclockwise) deflection of a lower extension of the primary leaf springs 32, the fourth or quaternary spring mode of the Q4 support system 45. For a simple horizontally cantilevered beam, the deflection or deformation x, is directly proportional to the product of the applied (concentrated) load, W, and the cube of the distance, L, from the load to the beam support, and inversely proportional to three times the flexural rigidity (El, the product of the moment of inertia of the beam cross-section and the modulus of elasticity), that is x = WL³/3EI.

For a fixed distance between support and load, and assuming modest deflections, all terms except for the load are constants and this relationship may be written as

For large deflections, the effective lever arm length is not a constant, but continuously decreases with increased deflection. This relationship is also a good approximation of the deflection of other beam configurations, such as the doubly cantilevered beam of Fig. 3a. Assume that, in an unoccupied state, the chair upper spring portion 60 is spaced away from both compression springs 40 and 42. For relatively small displacements, the spring assembly behaves as though these resilient members were absent as depicted in Fig. 3a. In such instances, the above linear relationship holds and is illustrated by the linear segment between the origin and the abscissa value at 56 in Fig. 5. Further assume that at this abscissa value, the upper spring portion engages the only the compression spring 42 as depicted in Fig. 3b. Now the upper spring portion begins to behave like an overhanging beam and the load vs. displacement curve slope increases due to the additional resistance of the member 42 and due to an effectively shorter lever arm length. Depending on the respective stiffnesses, the beam may actually experience an upward deflection between the bight 62 and resilient member 42. The relationship continues along the second linear path until the second resilient member 44 is engaged at abscissa value 58. Between the values at 56 and 58, the force required to depress the spring a distance x₂ is the force required to move it from its rest position into engagement with the compression spring plus the additional force required to compress the spring 42 and further flex the beam an additional incremental distance Xj W = k-i xι + k₂ Xj. If the upper spring portion is initially in contact with the compression spring 42, the two distances are the same and the overall load may be approximated by W = kι x₂ + k₂ x₂. When the deformation reaches point 58, further downward seat motion additionally compresses the resilient member 44 as illustrated in Fig. 3c and, depending on the relative stiffness of the upper spring portion 60 and resilient member 44, may deflect the lower spring portion 64 downwardly as in Fig. 3d. In either case, there is even more resistance to loading and the slope of the relationship increases beyond point 58. k₃ Xi expresses the additional force required to incrementally compress the member 44 beyond point 58 and k Xj expresses the additional force to depress the free lower spring portion 64. The natural resonant frequencies of the different spring elements corresponding to the differently sloping regions of the graph of Fig. 5 are, of course, different. If both resilient members 42 and 44 are initially engaged by the upper spring portion 60, the three line segments of Fig. 5 blend together into a single generally linear relationship between the net deflection x and force required to achieve the deflection may be approximated as W = (ki + k₂ + k₃ + k₄) x. When an occupant of the chair moves forward to exit the chair, the load may be shifted to the front seat edge as indicated by the egress load arrow 66 of Fig. 3e. Upper spring portion 60 separates from the two resilient members 42, 44 and behaves much as discussed in conjunction with Fig. 3a. However, the deformation or deflection is counterclockwise with the bight 62 opening as deflection increases. Thus, the first and second resilient members 42 and 44 contribute forces opposing spring compression to close the U-shape from its unstressed position, while the forces opposing opening the U-shape are contributed solely by the leaf primary spring 32. This relationship between load and deflection is illustrated by line 74 in Fig. 5. The effective lever arm is much shorter than earlier, the slope of line 74 is greater and the deflection in Fig. 3e is somewhat exaggerated. Note the force is still inboard of the front legs such as 14, and the probability of pivoting of the chair forwardly with potential injury to the occupant is minimized. Fig. 6 shows use of the Q4 assembly 45 for use in a recliner system 80. Recliner system 80 generally includes an outside housing 82, a pivotable support assembly 84, and a seat 86 employing a Q4 support system 45. Outside housing 82 incorporates a left (facing) area 88 and a right (facing) arm 90. Each of arms 88, 90 have (as shown for left arm 88) a set of outside foam panels 92 and an inside foam panel 94 associated therewith. Advantageously, each arm 88, 90 has at least a pair of feet assembly 96 (one of which is shown with respect to left arm 88) associated therewith. Pivotable support assembly 84 is composed of a pair of pivot panels 98, a pair of primary springs 100, a pair of balance springs 102, a pair of weight balance cams 5 104, a plurality of adapter plates 106, an adapter cross bar 108, and a plurality of threaded connector assemblies 110. A choice of type of foam panels to be used with the given faces of arms 88, 90 is dictated by the facing direction for such particular foam panels. The outside foam panels 92 are directed outward from the recliner 80. As such, softness and user0 comfort are not such driving issues, but durability is. It is useful for outside panels 92 to be durable yet provide some cushioning in that it is these respective outer faces of arms 88, 90 that will be most likely subjected to bumps, dings, etc., during everyday use. Thus, it is advantageous to employ, for example, half-inch thick high-density foam for such panels 92.5 As for the portion of an arm 88, 90 facing inwardly toward seat 86, this face will be in potential frequent contact with a user and not as subject to substantial dings and bumps as the other surfaces of the chair. As such, comfort is of a greater issue with inside foam panel 94. Thus, it is useful to use, for example, half-inch low-density trim foam for an inside foam panel 94. o Pivotable support assembly 84 is pivotably mounted relative to each of arms 88, 90 about respective pivot points 112 (via the use of threaded connector assemblies 110). Specifically, pivoting panels 98 of pivotable support assembly 84 are connected to respective arms 88, 90. To provide an interconnection between pivoting panels 98, adapter plates 106 are attached to the respective pivoting panels 98. Such plates 106,5 in turn, are linked together via adapter cross bar 108. The adapter plates 106 are connectively held to respective pivoting panels 108 via, for example, threaded connector assemblies 1 10, while adapter cross bar 108 is held to each of adapter plates 106 via a metallurgical weld and/or a mechanical fastening means. By providing further adapter plates 106 relative to Q4 support system 45, it is then possible to use the respective adapter plates 106 associated with each of Q4 support system 86 and pivotable support system 84 to thereby connect seat 86 to the recliner system 80. Incorporating pivotable support assembly 84 and the Q4 system 45 together allows a conventional style recliner motion the Q4 assembly rocking motion to be independently or simultaneously achievable in recliner 80. Each pivot panel 98 further has one weight balance cam 104, one balance spring 102, and one primary spring 100 associated therewith for use in controlling rotational aspects of pivot panels 98 about the respective pivot points 112. Such control of the spring force applied to the pivot panel enables changes in recliner operation force. That operation force is the force necessary to operate the recliner 80 to the upright or reclined positions. Due to the provision of the Q4 assembly 45, a rocking motion may be achieved at any time in either an upright or reclined position. Classic rocking motion utilized in classical rocking chairs may cause sea sickness or nausea for nursing mothers, patients with dementia, or other psychological problems. Classic rocking motion, in which the point of rocking is in contact with the floor, is shown in Fig. 7. Fig. 8 diagrammatically shows the use of a prior art glider rocker in which head movement is shown in an out and forward or out and up motion. The rocking focus, as seen by the user of the glide rocker, translates as the slider translates front and back, and is maintained beneath the user of the chair along the user's center of gravity. By use of the new Q4 quaternary spring suspension, as schematically illustrated in Fig. 9, the present invention moves the focus of the point of rocking forward of the center of gravity of the patient or user while preventing its translation along the ground. Additionally, the point of rocking, as viewed from the patient or user, is not centrally located around the patient's center of gravity but is located forward of the center of gravity. More preferably, the present invention attempts to locate the point of rocking at a point above the floor and most preferably on or forward of two-thirds the length of the seat's length and/or two-thirds of the user's depth in the seat. The requirements of this point of rocking that it is in front of the center of gravity of the user or more preferably in front of the two-thirds length of the user's depth from the edge of the seat to the user's posterior. This creates a rocking sensation that assists the user and does not cause difficult rocking side effects such as sea sickness or nausea. By use of the Q4 system 45 as shown in Figs. 1-5, the system is safe for use in patient's chairs, since the patient's feet have no ability to come off of the ground because of rocking. Figs. 10a-10c and 11 together illustrate some of the key operative features of Q4 recliner system 80. As indicated in Figs. 10a-10c, recliner 80 provides for the option of reclining movement, as indicated by direction R1 , and rocking movement, as indicated by direction R2. The Q4 suspension system 45 mounts to pivot board/panel

98 which is rotatable around pivot point 112 over the center of the load, indicated by CL. Reference point A (proximate the trinary springs of Q4 support system 45) is shown to track the relative movement of seat 86 during reclining. To accomplish minimal movement in a direction R1 during reclining, the seat 86 must pass over a center of circular/arcuate movement for recliner 80. Additionally, since the angle of travel for reference point A is not very large, the movement of point A approximates a straight line. By being nearly linear, such a movement is easily made by a user, and it does not involve a sudden angular change (and thereby no rapid change in vertical position - up or down) which could be unpleasant for a user. 5 Once the seat 86 is in its reclined position, the design of recliner 80 is such that this position should be able to be retained without an additional position locking mechanism being necessitated. The reason for this is that the center of load CL is shifted during reclining, and this weight shift should be sufficient in keeping the seat in the reclined position. A significant forward shift of the weight of the person occupying o seat 86 would be needed in order to move the seat out of the reclined position. Gentle rocking using Q4 support system 45 typically should not provide enough force for seat 86 to leave a reclined position. Thus, as can be seen in Figs. 10a-10c, it is possible to rock in both an upright position and a reclined position. Primary springs 100 and balance springs 102 each have a separate effect on5 the operation of pivotable support assembly 84 of recliner 80. Primary springs 100 act as tension/extension springs and are located so as to provide enough resistance to counterbalance part of the weight/load of the user. Balance springs 102 (i.e., centering springs) operate together with weight balance cams 104 to provide a centering action. Centering springs 102 are used to prevent a rapid reclining as the o seat 86 passes over the pivot vertical center line. While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover5 such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

WHAT IS CLAIMED IS: 1. A recliner comprising: an outside housing, said outside housing including a right arm and a left arm; a pivotable support assembly pivotably mounted between said right arm and said left arm, said pivotable support assembly configured for facilitating a selectable reclining action; a seat mounted on said pivotable support assembly, said seat including a quaternary spring support system therein, said quaternary spring support system configured for facilitating a selectable rocking action of said seat. 2. The recliner of claim 1 , wherein said pivotable support assembly comprises a pair of pivot panels and an adapter assembly, one said pivot panel being pivotably connected to said right arm, the other said pivot panel being connected to said left arm, said adapter assembly being mounted to each said pivot panel, said seat being operatively connected to said adapter assembly. 3. The recliner of claim 2, wherein said pivotable support assembly further comprises a plurality of control springs, said control spring being mounted relative to said pivot panels, said control springs being configured for regulating the reclining action capable of being generated via said pivotable support assembly. 4. The recliner of claim 1 , wherein said quaternary spring support system comprises: a primary leaf spring having a double-cantilever, U-shape, said U-shape having a first extension, a second extension, and a bight portion, said bight portion coupling said first extension and said second extension, said first extension and said second extension each being capable of acting as a spring; a first resilient member fixed to one of said first extension and said second extension and engageable with the other of said first extension and said second extension; and a second resilient member spaced from said first resilient member, said second resilient member fixed to one of said first extension and said second extension and engageable with the other of said first extension and said second extension. 5. The recliner of claim 4, wherein said primary leaf spring is fabricated of spring steel, and said first resilient member and said second resilient member are each compression springs. 6. The recliner of claim 4, wherein said first extension is longer than said second extension, said first extension being generally parallel to said second extension when not subjected to loading. 7. The recliner of claim 4, wherein said quaternary spring support system further comprises a second said primary leaf spring, a second said first resilient member, and a second said second resilient member.