The present invention relates to exercise equipment, and more particularly to exercise treadmills, and still more particularly to suspension systems for supporting the deck of the exercise treadmill above an underlying frame structure.
Exercise treadmills are widely used in spas, exercise clubs and also in individual residences to enable users to walk, jog or run indoors. This is especially useful during inclement weather and also at night or at other times when exercisers do not desire to run outdoors. Most exercise treadmills include first and second roller assemblies that are transversely mounted at the ends of a frame. An endless belt is trained about the roller assemblies. The upper run of the belt is supported by an underlying deck positioned between the belt and the frame.
Efforts have been made to reduce the impact on the user""s limbs and joints when jogging or running on a treadmill. One method of reducing the impact on an exerciser""s body is disclosed by U.S. Pat. Nos. 4,974,831 and 4,984,810. In the treadmills disclosed by these patents, the rear end of the deck is pivotally mounted to the frame, with the forward end of the deck supported by a suspension system. In the ""831 patent, the suspension system consists of a fairly complicated lever arm assembly and cooperating shock absorbers. Striding on a deck results in pivoting of the lever arms and extension of the shock absorbers, thereby to dampen the impact of the user""s feet. A drawback of this shock absorption system is its complex nature, rendering it costly to manufacture.
In the ""810 patent, the forward end of the treadmill deck was supported by a conventional compression spring and separate shock absorber. Placement of the spring and shock absorber at the very front of the deck imposes considerable bending stress on the deck.
Other conventional treadmills have utilized rubber blocks positioned between the deck and the underlying frame to absorb impact. One such conventional treadmill is disclosed in French Patent No. 2,616,132. A treadmill deck is mounted above the frame members on a plurality of flexible pads. Bushings are inserted into the top and bottom of each pad, and bolts depending downwardly from the deck and upwardly from frame are received within the corresponding bushings. The bolts serve to position the flexible pads between the deck and frame for shock absorption.
U.S. Pat. Nos. 5,336,144 and 5,454,772 disclose a deck supported above a frame by a plurality of cup-shaped elastomeric springs. The elastomeric springs reversibly deform during downward deflection of the deck toward the frame. The elastomeric springs have side walls of tapering thickness. As a result, the resistance to the downward travel of the deck provided by the elastomeric springs is proportional to the degree of deflection of the deck toward the frame. One drawback of this particular treadmill construction is that the elastomeric springs are fixed in place and individually define a rather small bearing area.
The present invention provides an exercise treadmill having a frame, first and second roller assemblies rotatably mounted on the frame, and an endless belt trained about the first and second roller assemblies. The exercise treadmill also includes a deck disposed between the frame and the upper run of the belt. A pivot connection pivotally connects the rearward end portion of the deck to the frame. Elongate elastomeric spring members are disposed between the frame and the deck at a location intermediate the ends of the deck to support the deck spaced above the frame. The elastomeric springs reversibly deform to resist a deflection (downward movement) of the deck toward the frame when the exerciser strides on the endless belt. The resistance provided by the elastomeric spring members is proportional to the extent of deflection of the deck.
In a further aspect of the present invention, the elastomeric spring members are mounted on the side rails of the frame and underlie marginal side portions of the deck.
In another aspect of the present invention, the elastomeric springs include a base portion and a bulbous body portion extending upwardly from the base portion. The body portion is domed or crowned at its top to define an outwardly convex shape. The interior of the elastomeric spring between the base portion and the body portion is hollow or partially hollow. As a result, the body portion deflects downwardly under the force imposed on the deck by the exerciser.
In an additional aspect of the present invention, the wall thickness of the body portion of the elastomeric spring is greater at the intersection of the body portion with the base of the elastomeric spring. The wall thickness of the body portion decreases in the direction away from the base portion, reaching a minimum thickness at the top of the domed body portion. As a result, when the deck imparts a downward load on the elastomeric springs, the top central portion of the body portion of the elastomeric spring deflects downwardly into the hollow interior, rather than the body portion deflecting sideways, which could occur if the elastomeric spring was of solid construction. Also, the resistance imposed on the deck by the elastomeric spring increases as the deck deflects downwardly, thereby providing a variable rate spring.
In another aspect of the present invention, the spring may be constructed so that its rate of deformation may be selectively altered. In this regard, a compressible insert is sized and shaped to be selectively insertable to a desired degree into the hollow body portion of the spring. In cross-section, the insert may correspond to the cross-sectional shape of the hollow body portion of the spring. Also, the spring may be tapered along its length. In another configuration, the body portion of the spring may be adapted to receive a compressible fluid thereby serving as a bladder. In a more specific aspect of the present invention, the compressible fluid may be composed of air, with the air being supplied to the bladder by an air pump. Also in a more specific aspect of the present invention, a valve or other means may be provided for discharging the compressible fluid from the bladder.
In a further aspect of the present invention, the pivot connection at the rearward end of the deck includes a spindle mounted on the frame side member to engage with a hinge bracket mounted to the underside of the deck. By this construction, the rearward end portion of the deck is pivotally attached to the frame about an axis extending transversely to the length of the deck.