Heretofore elastomeric support members of various designs have been employed to provide support for and control motion of a load. Where a vehicle or apparatus in which a sway bar is employed is subjected to relatively light impact a sway bar support member or bushing which provides linear displacement in response to impact may be acceptable. However, where large impact loads are encountered, as, for example, in a sway bar for a skip car receiving and transporting heavy loads of rock or ore in a quarry, a bushing which provides an increasing degree of energy absorption in response to large impact loads is required.

Accordingly, it is the general aim of the present invention to provide a non-linear spring rate responsive elastomeric support member which enables disproportionately large load displacements for improved energy absorption in response to large impact loads.

SUMMARY OF THE INVENTION In accordance with the present invention a non-linear spring rate support member comprises a base, a carrier, and a plurality of support ribs formed from resilient elastomeric material and angularly spaced about a common axis.

The support ribs extend radially between and connect the carrier and the base to mount the carrier on the base between the base and the common axis. In accordance with a more particular embodiment of the invention the support member comprises a non-linear spring rate responsive sway bar bushing formed from resilient elastomeric material and having an axially elongated tubular inner portion or carrier defining a bore extending axially therethrough for receiving and containing a portion of a sway bar therein. An elongated base or outer portion of the bushing is supported in radially outwardly spaced relation to the inner portion or carrier by radially extending support ribs angularly spaced about the axis of the bore and connected to and extending between the inner portion and the outer portion. The support ribs maintain the inner portion in radially inwardly spaced relation to the outer portion between the outer portion and the axis of the bore.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a transverse sectional view through a non-liner spring rate responsive sway bar bushing embodying the present invention.

Fig. 2 is a perspective view of the bushing shown in Fig. 1 illustrating an application thereof.

Fig. 3 is a sectional view taken generally along the line 3-3 of Fig. 1.

Fig. 4 is a load vs. deflection graph of the sway bar bushing application shown in Fig. 2.

Fig. 5 is a perspective view of another non-linear spring rate responsive support member embodying the invention.

Fig. 6 is a top plan view of the support member of Fig. 5.

Fig. 7 is a somewhat enlarged end elevational view of the support member of Fig. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to the drawings and referring first particularly to Figs. 1 and 2, a non-linear spring rate responsive support member or sway bar bushing embodying the present invention is indicated generally by the reference numeral 10. The illustrated sway bar bushing 10 essentially comprises a unitary body molded or otherwise formed from a resilient elastomeric material, such as a rubber compound, and includes an axially elongated tubular inner portion or carrier 12 which has a bore 14 extending axially through it for receiving and containing a portion of a sway bar therein. The bushing 10 further includes an elongated outer portion or base 16. A plurality of radially extending support ribs 18, 18' angularly spaced about the axis of the bore 14 and integrally connected to and extending between the inner portion 12 and the outer portion 16 mount the inner portion 12 in radially inwardly spaced relation to the outer portion, substantially as shown.

Considering now the sway bar bushing in further detail, the illustrated bushing member 10 is preferably made from an elastomeric material of substantially uniform thickness. The inner and outer portions 12 and 16 preferably comprise generally cylindrical tubular portions maintained in coaxial alignment with each other by the ribs or spokes 18, 18'which are angularly spaced about a common axis coincident with the central axis of the bore 14. The bore is also

generally cylindrical to receive and retain a complementary cylindrical portion of a sway bar, such as the bar shown in Fig. 2 and indicated generally by the letter B.

In accordance with presently preferred construction, the sway bar bushing 10 has four equiangularly spaced apart and radially extending ribs or spokes 18, 18'. Preferably, and as shown, the inner portion or carrier 12 and the outer portion or basel6 are of substantially identical axial length, the inner portion 12 being wholly disposed within the outer portion of the bushing 10. The ribs 18, 18 are integrally connected to the inner and outer portions 12 and 16 along the entire lengths of the inner and outer portions.

A typical application of the bushing 10 is shown in Fig. 2. The mounting base 16 is secured in fixed position relative to a part of an apparatus (not shown) to support and control movement of an associated portion of the sway bar B connected to another part of the aforementioned apparatus. Preferably, and as illustrated, the sway bar B is generally constrained within the apparatus to move in the direction indicated by the directional arrows F, F in response to an impact force acting upon the apparatus. The presently preferred geometry and mounting arrangement of the bushing 10 is such that sway bar movement occurs generally within a diametric plane of the cylindrical bushing, that is a plane which bisects the angles between the equiangularly spaced apart spokes at diametrically opposite sides of the sway bar bushing. In Fig. 2 the spokes at one side of the bushing are indicated at 18, 18, whereas the spokes at the diametrically opposite sides are indicated at 18', 18'. The presently preferred spoke of angle relative to the direction of bar movement is shown at a in Fig. 1 and comprises 45 degrees.

When the apparatus (not shown) is subjected to an impact force which causes the sway bar B to move in the direction of the arrows F, F in Fig. 2 the spokes 18', 18'will be subjected to compressive force whereas the spokes 18, 18 will be in tension. It should also be apparent that the spokes will undergo a change in angular relationship relative to each other. This change in the angular relationship between the spokes causes a non-linear spring rate to develop within the bushing acting upon the sway bar B, whereby small impacts result in relatively small displacements of the bar while large impacts result in disproportionately large displacements of the bar and greater energy absorption of large impacts. The resulting disproportionate deflection of the bar in response to a high impact load is graphically illustrated in Fig. 4.

Further referring to the drawings and considering now Figs. 5-7, another non-linear spring rate responsive support member embodying the present invention is indicated generally by the reference numeral 10a. The illustrated support member 10a essentially comprises a unitary elastomeric body formed from a rubber compound and having a uniform thickness and a generally trapezoidal cross-sectional configuration. As it appears oriented in the drawings, the support member 10a includes a generally rectangular base portion 16a defining a downwardly facing mounting surface 15. The support member further includes a carrier 12a, defining an upwardly facing support surface 17, and a pair of support ribs 18a, 18a angularly spaced about a common axis, indicated by the letter A and integrally connected to and extending radially between the base portion 16a and the carrier 12a and mounting the carrier portion on the base portion 16a between the base portion and the common axis A shown in Figs. 5 and 7. The ribs 18a, 18a form equal angles with the base 16a. In accordance with presently preferred construction, each of the base angles, indicated at 3, in Fig. 7, equals 45 degrees.

The illustrated support member 10a may provide entire support for a load such as an article or apparatus mounted on the support surface 17, but not shown, or may be employed with other support members of like kind to provide a support structure for carrying a load.

The support member 10a is particularly adapted to provide a non- linear spring rate reaction to an impact force acting in a direction generally normal to the base 16a and favorable energy absorption in response to high impact loads.

This reaction is graphically illustrated in Fig. 4.