Patent Publication Number: US-6669298-B2

Title: Seat assembly including resilent friction member

Description:
This is a Divisional Application of U.S. patent application Ser. No. 09/349,886, filed Jul. 8, 1999 now U.S. Pat. No. 6,386,528. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to the area of damping devices. Specifically, it relates to devices employing a resilient element operable in frictional contact with another member for generating damping forces. 
     BACKGROUND OF THE INVENTION 
     Various devices are known which utilize resilient elastomer elements to produce a damping force to control or minimize shock and/or vibration or to generate a locking function. In such prior art devices, the resilient elastomer element is in frictional engagement with another member. 
     Such devices are, for example, disclosed in U.S. Pat. No. 5,720,369 to Thorn entitled “Adjustable, Lockable Devices,” U.S. Pat. No. 5,634,537 to Thorn entitled “Locking and Positioning Device,” U.S. Pat. No. 5,613,580 to Young entitled “Adjustable, Lockable Strut”, U.S. Pat. No. 5,257,680 to Corcoran et al. entitled “Surface Effect Dampers Having Both A Hysteresis and A Frictional Component, U.S. Pat. No. 5,183,137 to Siwek et al. “Dual Rate Surface Effect Dampers” U.S. Pat. No. 4,964,516 to Thorn entitled “Damped Extended-Motion Strut,” U.S. Pat. No. 4,957,279 to Thorn entitled “Fluidless Multi-Directional Motion-Damping Mount,” U.S. application Ser. No. 09/040,694 to Thorn et al. entitled “Resistance Generating Device,” and U.S. application Ser. No. 09/040,694 to Miller et al. entitled “Elastomer Damper,” all of which are commonly assigned to the assignee of the present invention. 
     Although these devices are adequate for their intended purposes, they each exhibit certain inadequacies that make them unattractive candidates for providing damping forces between relatively moveable members in low-cost applications. Moreover, many of the devices available heretofore include large numbers of components and provide damping forces that may vary significantly with tolerance variations. 
     Therefore, there is a long felt, and unmet, need for a simple, durable, maintenance free, and cost-effective damper for providing damping forces between relatively moveable members, and in particular, a damper configuration which is insensitive to tolerance variations due to manufacturing processes used to produce it. 
     SUMMARY OF THE INVENTION 
     The present invention provides a friction damper of simple construction including a resilient friction element in frictional engagement with a surface of another member. Moreover, the invention provides a damper exhibits excellent tolerance insensitive damping. The damper includes a tubular outer member and an inner member assembly reciprocatable therein. The tubular outer member includes a recess having an inner surface of preferably substantially constant diameter, and a first attachment hole radially intersecting the recess. The inner member assembly includes a shaft having a cross-wise directed second attachment hole and a resilient friction member preferably fixedly mounted (e.g., by bonding or mechanical fastening means) to the shaft. The resilient friction member is disposed in the recess in precompressed frictional contact with the inner surface of the outer member. 
     The tubular outer member is preferably open at its first and second ends and the constant diameter is preferably provided along its entire axial length. The shaft preferably includes a first dimension portion with a smaller dimension portion extending from it. The first dimension portion is preferably integral with the smaller dimension portion. Alternatively, the second portion may be a separate member which engages the first. 
     Various means may be employed for fixedly mounting the resilient friction member to the shaft. Most preferably, the friction member is bonded to the shaft. Alternatively, the smaller dimension portion may include a deformable portion that is deformed during assembly to secure the resilient friction member onto the shaft. According to another embodiment, the smaller dimension portion may include a taper on an end thereof and the shaft may include first and second steps thereon. During assembly the resilient friction member is received over the taper and snaps onto place between the steps. In another embodiment, a tinnerman-type lock washer is received over the end of shaft to fixedly secure the resilient friction member thereon. 
     As previously mentioned, in several other embodiments, a smaller dimension portion includes a separate member that engages a hole in the first dimension portion (e.g., a rivet or fastener). For example, the separate member may include a thread formed on the smaller dimension portion that engages a like thread formed on the hole. Moreover, the separate member may include one or more projections that snap into the first portion to retain the friction member in place. 
     According to a preferred embodiment, the resilient friction member preferably comprises at least one protrusion (most preferably a plurality of ribs) formed on an outer surface thereof. The ribs may be axially or radially oriented. These ribs are precompressed against the surface and allow significant variations in the tolerances of the members yet still providing adequate damping forces. Preferably, the resilient friction member is lubricated to provide more consistent damping and to minimize break away forces. If adjustment to the damping level is desired, one or more o-rings may be received over the resilient friction member thereby increasing its surface area. 
     In accordance with another embodiment of the invention, a plurality of undulations may be formed on the shaft for fixedly securing the resilient friction member to it. The undulations may be corrugations or jagged ridges over which the resilient friction member is received. 
     The damper according to the invention finds excellent utility for damping the movement of spring biased seatbacks. Therefore, according to another aspect of the invention, a tiltable seat assembly is provided which comprises a first seat member, a second seat member movably mounted on the first seat member, a spring biasing the second seat member relative to the first seat member and a damper including a resilient friction member linearly reciprocatable in an outer member interconnecting between the first and second seat members. 
     In more detail, a preferred embodiment of the damper comprises a tubular outer member including first and second open ends, a recess having an inner surface of substantially constant diameter, and a first attachment hole intersecting the recess at the first end thereof; and an inner member assembly received in the second end having a shaft with a first portion including a second attachment hole formed therein and a smaller dimension portion extending therefrom, and a resilient friction member fixedly mounted to the smaller dimension portion, the resilient friction member disposed in the recess in frictional contact with the inner surface. 
     According to another aspect, the invention comprises a tiltable seat assembly having a first seat member, a second seat member movably mounted on the first seat member, a spring biasing the second seat member relative to the first seat member, and a damper interconnected between the first and second seat members, the damper further comprising a first member having an engagement surface and attaching to one of the first and the second seat members, and a second member linearly reciprocatable relative to the first member and attaching to the other of the first and second seat members, the second member including a resilient friction member disposed in frictional contact with the engagement surface wherein the damper provides damping between the first and second seat members. 
     It is an advantage of the invention is that it provides a damper with simple, durable and low-cost construction. 
     Another advantage of the invention is that it provides adequate damping forces over relatively broad tolerance ranges. 
     Yet another advantage of the invention is that it provides cost-effective damping for controlling motion in spring-biased chairback applications. 
     The above-mentioned and further features, advantages and characteristics of the present invention will become apparent from the accompanying descriptions of the preferred embodiments and attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings form a part of the specification and illustrate several embodiments of the present invention. The drawings and description, together, serve to fully explain the invention. In the drawings, 
     FIG. 1 is a perspective view of an embodiment of the damper in accordance with the present invention, 
     FIG. 2 is a cross sectional view of the damper taken along section line  2 — 2  of FIG. 1, 
     FIG. 3 is a perspective view of an alternate inner member assembly in accordance with the present invention, 
     FIGS. 4-6 are cross sectional side views of other inner member assemblies in accordance with the present invention, 
     FIG. 7 is a cross sectional side view of another damper in accordance with the present invention, 
     FIG. 8 is a cross sectional side view of another damper including o-rings for damping augmentation, 
     FIG. 9 is an end view of an inner member assembly in accordance with the present invention including a ribbed resilient friction member, 
     FIG. 10 is a cross sectional side view of the inner member assembly taken along line  10 — 10  of FIG. 9, 
     FIGS. 11-13 are cross sectional side views of other inner member assemblies in accordance with the present invention, and 
     FIG. 14 is a partially sectioned underside view of a tiltable seat assembly in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the Drawings where like numerals denote like elements, FIGS. 1-13 illustrate various embodiments of the damper  20  and inner member assemblies  32  utilized therein. The damper  20  is useful for providing damping forces between any two relatively-movable structural members. According to the invention, the damper  20  includes an outer member  22  and an inner member assembly  32  linearly reciprocatable therein. 
     The outer member  22  preferably comprises a substantially-rigid, tube and includes a cylindrical recess  23  having an inner surface  24  of substantially constant diameter extending entirely along its length from a first open end  26  to a second open end  28  thereof. A first cross-wise oriented attachment hole  30  intersects the recess  23  at the first open end  26  of the outer member  22  and is used for pivotally attaching the damper  20  to a first structural member (see FIG.  14 ). Preferably, the outer member  22  is manufactured from steel, aluminum or plastic tube. The inner surface  24  preferably includes a smooth finish. Moreover, the surface  24  may be treated, for example with a Teflon coating to improve its friction and/or wear characteristics. In cases where the outer member  22  is not shown (FIGS. 3-6,  9 - 13 ), the various inner member assemblies  32  depicted are intended to be used with an outer member  22  identical to that shown in FIGS. 1-2. 
     The inner member assembly  32  includes a substantially rigid shaft  34  (e.g., plastic (Nylon), steel or aluminum, etc.) having a second cross-wise oriented attachment hole  36  formed therein, and a resilient friction member  38  fixedly mounted on the shaft  34 . The term “fixedly mounted” means that the member  38  is mounted to the shaft and that it cannot move relative thereto by any appreciable amount, but may move slightly within bounds. The second hole  36  is used for pivotally attaching the other end of the damper  20  to a second structural member (see FIG.  14 ). The assembly  32  is received in the second open end  28  of the outer member  22  and is reciprocatable therein. Resilient friction member  38  is disposed in the recess  23  in frictional engagement with the inner surface  24  and is preferably radially precompressed such that there is always an interference fit between the outer member  22  and the resilient friction member  38 . 
     The shaft  34  preferably includes a first dimension portion  35  with a smaller dimension portion  37  extending axially from it. Except as shown in FIGS. 12 and 13, both portions  35 ,  37  are generally cylindrical. Most preferably, the first dimension portion  35  is formed integrally with the smaller dimension portion  37  and are manufactured from the same material. The resilient friction member  38  is preferably fixedly mounted to the smaller dimension portion  37  of the shaft  34  by a suitable bonding process, for example. The process may include a transfer, injection or compression bonding process, for example, where a suitable adhesive is applied to the smaller portion  37  of shaft  34  as shown in FIG. 2, and elastomer is molded thereto (within a mold) forming the appropriate shape and contours on the resilient member  38 . Such processes are known to persons of ordinary skill in the art. Alternatively, the resilient friction member  38  may be molded separately in a molding process and subsequently cold bonded to the shaft  34  by coating the pertinent portions of the shaft  34  with a suitable cold bond adhesive, such as a cyanoacrylate adhesive or the like. In the case where the resilient friction member  38  is molded, it includes a through bore  50  formed therethrough. 
     Most preferably, as shown in FIGS. 2-6, and  8 - 13 , the resilient friction member  38  includes at least one outwardly-extending protrusion  40  formed on a radial outer surface thereof. The at least one formed protrusion  40  is in direct frictional contact with the surface  24 . Most preferably, the at least one protrusion  40  comprises a plurality of preferably equally-spaced outwardly projecting ribs formed on an outer surface of the resilient friction member  38 . For example, as shown in FIGS. 2,  4 - 6 , and  8 , the ribs may include a radial orientation and form a corrugated profile where each such protrusion  40  is preferably rounded at it&#39;s point of contact with the surface  24 . In each of the illustrated embodiments herein, the resilient friction member  38  may be lubricated with an appropriate lubrication, such as a grease. A grease which is found to be very effective is 3451 or 3452 available from Dow Corning or Damping Nygel available from NYE Lubricants. The valleys formed between the protrusions  40  serve the purpose of carrying and dispersing the lubricant. Suitable resilient materials for the resilient friction member  38  comprise Butyl, Silicone, Neoprene, or any other suitable elastomeric materials which are substantially incompressible and elastic. Most preferably, a natural rubber material exhibiting a Shore A durometer of about 50-60 is found to exhibit the combination of desirable characteristics for the damper  20 . Alternatively, the rubber may be internally lubricated with appropriate additives, as is known to those of ordinary skill in the art. 
     According to another aspect of the invention, the at least one protrusion  40  on the friction member  38  is formed of a plurality of ribs as illustrated in FIGS. 3,  9 - 11 , and  13  that may be axially oriented (generally parallel to the shaft axis). Preferably, the protrusions  40  comprise a rectangular, square or trapezoidal profile in radial cross section. The friction member  38 , in these embodiments, may be bonded directly to the smaller portion  37  of shaft  34  as shown in FIG. 3, or mechanically locked to the shaft as in FIGS. 9-11 and  13 . In both the radially and axially oriented cases, it is preferable that the ribs  40  of the resilient member  38  be precompressed radially in the range between about 5% and about 30%, and most preferably about 10%. This ensures that for normal manufacturing tolerance ranges, the ribs  40  will remains precompressed and adequate damping will be retained. 
     In the FIGS. 9-10 embodiment for example, the shaft  34  comprises a taper  47  at its terminal end over which the resilient friction member  38  is received. The shaft  34  also includes a first dimension portion  35  and a smaller dimension portion  37  extending therefrom forming a first step  46  at an interface between the portions  35 ,  37 . The taper  47  formed on the smaller dimension portion  37  terminates at a second step  48 . During assembly, the resilient friction member  38  is received over the taper  47  and snaps onto place on the cylinder of portion  37  between the steps  46 ,  48 . Suitable cold bond adhesive may be applied to the shaft  34  prior to assembly to add a secondary means for fixedly mounting the resilient friction member  38  to the shaft  34 . The friction member  38 , in this embodiment, includes a plurality of equally-spaced, radially-directed projections or ribs  40  which have a rectangular cross section. The shaft  34  of the assembly  32 , as well as those shown in FIGS. 2,  4 ,  6 ,  8  and  11 - 13 , is preferably formed from an injection molded plastic such as Nylon in an injection molding process as is known to those of ordinary skill in the art. 
     In the embodiment of FIG. 11, the mechanical retaining means used to fixedly secure the resilient friction member  38  to the shaft  34  comprises a tinnerman lock washer  60 . The through bore  50  of resilient friction member  38  is pressed over smaller dimension portion  37  (which is slightly larger than it) and the lock washer  60  is received over the portion  37  and is pressed thereon until it snuggly engages the axial end of the friction member  38 . The diameter of the washer  60  is preferably as wide as the diameter of the first portion  35  adjacent to the step  46 . The tinnerman washer  60  is of the type that goes on relatively easily, but is extremely difficult to remove thereby permanently securing the friction member  38  in place against step  46 . A taper  47  may be included on the end of portion  37  to aid in pressing on the friction member  38 . 
     FIG. 13 illustrates another embodiment of inner member assembly  32  including a plurality of undulations  58  formed on the smaller portion  37  of shaft  34 . In this embodiment, the undulations  58  comprise a series of jagged projections that engage the throughbore  50  of friction member  38 . The outer diameters of the jagged portions  58  are slightly larger than the diameter of the through bore  50  in its undeformed state such that the friction member  38  is received over the shaft portion  37  in an interference fit relationship. Supplemental cold bond adhesive, as afore-described, may be employed if desired. The jagged portions  58  may include a gentle slope of their onward side and a steep (generally straight radially outward or even undercut) slope on their backside, such that the friction member  38  is easily pressed on, but once pressed on and positioned to abut the step  46 , is very difficult to remove. As in the previously described embodiment, a taper  47  may be added to the end of shaft portion  37  to aid in pressing on the friction member  38 . Other forms of jagged edges may be employed on the shaft  34 . For example, the jagged ridges may only traverse part way around the circumference of the shaft  34  or be included only the part of the portion  37  near the end thereof. 
     FIG. 12 illustrates another embodiment of inner member assembly  32  wherein the projections  40  are created by a plurality of undulations  58  formed on the smaller portion  37  of shaft  34 . Prior to assembly, the resilient friction member  38  comprises an annulus of elastomer. Upon pressed the bore  50  over the portion  37 , the member  38  deforms to form the protrusions  40  and take on the shape shown in FIG.  12 . This deformation fixedly secures the sleeve-shaped friction member  38  to the shaft  34 . Preferably, the inner dimension of the sleeve  38  in its undeformed state is slightly smaller than the smallest diameter of the portion  37  thereby ensuring contact along the entire axial length of the shaft portion  37 . A taper  47  may be included at the end of portion  37  to help facilitate stretching the sleeve  38  over it. Supplemental cold bond adhesive may be employed, if required for the application. 
     FIGS. 4-7 illustrate various other means for mechanically and fixedly mounting the resilient friction member  38  on the shaft  34  of member assemblies  32 . For example, as illustrated in FIG. 4, the bore  50  of friction member  38  is received over the integral shaft portion  37 ; the shaft  34  comprising a deformable material such as thermoplastic or aluminum. A washer  62  is received over the deformable shaft portion  37  and securely abuts the end of the friction member  38 . A tool, utilizing pressure and/or heat, deforms (e.g., crimps) the deformable end portion  42 . The end portion  42  is deformed such that it retains the washer  62  against friction member  38  and the friction member  38  against step  46 . 
     FIG. 5 illustrates a similar assembly  32  as compared to FIG. 4, except the shaft portion  37  comprises a separate member  52  which engages the first portion  35 . Preferably, the separate member  52  extending from the first portion  35  is a rivet. The rivet  64  is received through, and engages, hole  54  formed in the first portion  35  and a head  65  thereof abuts a counter bore  67 . The bore  50  of friction member  38  is received over the portion  37  and then washer  62  is placed adjacent to its axial end. Upon crimping the deformed end  42  onto washer  62 , the friction member  38  is securely mounted to shaft  34  and snuggly presses against step  46 . 
     FIG. 6 illustrates another assembly  32  wherein the shaft portion  37  comprises a separate member  52  which engages a hole  54  in the first portion  35 . In particular, the separate member  52  includes one or more projections  44  that snap into the first portion  35  to fixedly mount the resilient friction member  38  on the shaft  34 . The projection  44  may be a one or more small bumps, a ring, or other interfering projection that is elastically deformed and likewise elastically deform the hole  54  when pressed therethrough. The bore  50  of friction member  38  is first mounted on portion  37 . This subassembly is than pressed far enough inward such that the projection(s)  44  reach the counterbore  67 . The projections(s)  44 , upon passing through hole  54 , will expand back out and the hole  54  will reform to its original shape thereby locking the portion  37 , and thus the friction member  38 , to the portion  35 . A head  68  formed on the portion  37  preferably has a diameter which is at least as large as the diameter of the portion  35  at the step  46  thereby adequately retaining the member  38 . The dimension from the head  68  to the projection(s)  44  is such that the friction member  38  is securely held in place when installed. 
     FIG. 7 illustrates another assembly  32  wherein the shaft portion  37  is a portion of a separate member  52 . The separate member  52  engages a threaded hole  54  in the first portion  35 . In particular, separate member  52  is a bolt-like fastener that includes head  68  and a threaded portion that engages a like threaded portion in the hole  54 . The head  68  formed on the portion  37  preferably has a diameter which is at least as large as the diameter of the portion  35  at the step  46 . The resilient friction member  38  shown may be an annular sleeve or include axial fibs as shown in the FIG. 3 embodiment. The bore  50  of friction member  38  is received over fastener  52  and when the fastener  52  is bottomed in hole  54  the resilient friction member (preferably, a substantially incompressible elastomer) will bulge radially to assert a radial force against the wall  24  of outer member  22  and be secured against both the head  68  and step  46 . Alternatively, the portions  35 ,  37  may be devoid of threads and the portion  37  may be ultrasonically welded to the first portion  35  or otherwise secure thereto by an appropriate adhesive. As in all the embodiments herein described, movement of the inner member  32  relative to the outer member, via applying forces at holes  30 ,  36 , produces a damping force that will retard motion of the members the damper  20  is attached to (see FIG.  14 ). 
     FIG. 8 illustrates another embodiment of damper  20  and inner member assembly  32  therefor. The damping produced by this embodiment is adjustable by one or more o-rings  56  that are received over the resilient friction member  38 . The o-rings  56 , even when lubricated, remain stationary within the valleys between the ribs  40  and in contact with the surface  24  of recess  23 . The o-rings  56  slide against when member  22  when the member  22 ,  32  move relative to one another. Adding o-rings increases the effective friction area and friction force obtainable from the damper  20 . In this embodiment, the bore  50  of friction member  38  is received over portion  37  extending from integral portion  35  and is preferably fixedly mounted to shaft  34  by suitable cold bond adhesive. 
     FIG. 14 illustrates the damper  20  of FIGS. 1 and 2 installed in a tiltable seat assembly  21 . The assembly  21  includes a first seat member  25 , a second seat member  27  movably mounted (most preferably pivotally mounted about a lateral axis A—A) on the first seat member  25 , a spring  29  (e.g., a coil spring) biasing the second seat member  27  relative to the first seat member  25 , and a damper  20  pivotally interconnected to the first  25  and second  27  seat members. The first member  25  may be, for example, a base that attaches to the underside of a chair&#39;s seat frame (not shown) as is known to persons of ordinary skill in the art. The second seat member  27  may be a U-shaped connector which pivotally attaches at a pivot pin  53  to the first member  25 . The seatback upright member  31  is secured by threaded knob  51  to the second member  27  and has the seatback (not shown) mounted thereon. 
     The spring  29  is preferably a coil spring including a first end  33   a  which contacts an underside portion of the first member  25 , a second end  33   b  which contacts a portion (the lateral pin  45 ) of the second member  25  and a central portion  33   c  which surrounds the pivot pin  53 . The spring  29  is preferably installed in a pretensioned condition and biases the second member  27  into a forward position (as shown). Alternate springs types may be employed, such as elastomer tubeform bushings, torsion springs, plate springs, etc. 
     The damper  20  according to the invention interconnects between a lateral cylindrical rod  43  of the first member  25  and a lateral cylindrical pin  45  of the second member  27 ; both of which are offset from the pivot pin  53 . In particular, rod  43  is pivotally received through attachment hole  30  and pin  45  is pivotally received through attachment hole  36 . A stroke limiter pack  41  formed, for example, from a plurality of stamped plate members  49  and interspersed washers  78 , also attaches between the first  25  and second  27  members. A slot  49  formed in each of the plates  49  limits the forward and backward strokes of the second  27  relative to the first  25  seat member. The slotted first end  41   a  of the stroke limiter pack  41  pivotally attaches to a cylindrical lateral rod  43  of the first member  25 . A second end  41   b  of the limiter  41  pivotally attaches to a similar cylindrical lateral pin  45  of the second member  27 . The damper  20  damps pivotal motions between the members  25 ,  27 . 
     The assembly  21  may also include a locking mechanism  72  for locking the second member  27  in any intermediate position (end positions determined by the slot  49 ) relative to the first member  25 . In particular, a coil spring  73  is received over the rod  43  and is precompressed between an inside end of a clevis  74  and a flange  75  of the first member  25 . This spring  73  axially loads a cylindrical spacer  76  against the limiter pack  41  which then snugged against a stationary washer  77  welded to rod  43 . This axial loading frictionally locks the members  25 ,  27  from relative pivotal movement. 
     In more detail, the washers  78  in the limiter pack  41  are interspersed between the plates  79 . When the lever  80  (pivotally mounted by pin  81  to clevis  74 ) is in the position shown, the preload of spring  73  is relieved, eliminating the axial loading of spacer  76 , and enabling a change in position. Rotation of the lever  80  downward (out of the paper) again applies an axial load to spacer  76  thereby frictionally locking the washers  78  and plates  79  between the spacer and the stationary washer  77  and resultantly locking the pack  41 . This locks the relative position between the members  25 ,  27 , as desired by the user. 
     In operation (provided the lock mechanism  72  is unengaged), when the user exerts a force on the seatback upright  31  by leaning back in the chair, the second member  27  pivots downward (out of the paper), loads the spring  29 , and reciprocates the first member  22  of the damper  20  relative to the second member assembly  32 . The pin  43  slides in slot  49  to the extent of the travel allowed. 
     The damper  20  is made up of a first member  22  and a second member  32  linearly reciprocatable therein. The first member  22  preferably comprises a cylindrical tube and includes a preferably smooth inner engagement surface  24 . The damper  20  is mounted between the rods  43 ,  45  as shown. However, it should be recognized that the orientation may be flipped such that the first member  22  is attached to the second seat member  27  and the second damper member  32  to the first seat member  25 . A resilient friction member  38 , preferably including a plurality of protrusions  40 , is disposed in frictional contact with the engagement surface  24  and the damper  20  provides damping between the first  25  and second  27  seat members to restrain pivotal motion thereof. The damping fosters a controlled movement of the seatback in both pivotal directions. Preferably, a sufficient level of damping force is provided such that the damper  20  prevents abrupt forward stops where the pin  43  contacts the end of slot  49  in the forward position and provides an adequate damped feel for all motions of the seat back. It should be recognized that although the damper of FIGS. 1 and 2 is illustrated in the seat assembly  21 , that any of the foregoing damper embodiments illustrated in FIGS. 3-13 may be used as alternatives. Moreover, the damper may be employed in any seat or other assembly to provide damping between relatively moving components. 
     In summary, it should be apparent from the foregoing that the present invention comprises a novel damper with an outer member and an inner member assembly linearly reciprocatable therein. The assembly includes a resilient friction member received in interference fit relationship with the housing to generate damping forces therebetween. The invention provides a low-cost damper that is simple and robust and particularly useful as a damper in tiltable seat assemblies. 
     While several embodiments including the preferred embodiment of the present invention have been described in detail, various modifications, alterations, changes, and adaptations to the aforementioned may be made without departing from the scope of the present invention defined in the appended claims. It is intended that all such modifications, alterations and changes be considered part of the present invention.