Of the preferred embodiments to be described hereinbelow,
As is known in the art, the dumbbell 10 comprises a generally cylindrical bar 12 extending axially between two end regions, the right end region 11 being illustrated in
A generally annular sleeve 16 having a flange portion 16a and a hub portion 16b is mounted on the bar axially outward of the weight plate 14. Preferably, the same is true at the unillustrated left end of the dumbbell. The annular sleeve has an inner diameter that fits over the bar 11, and is slid axially inward over the bar until it reaches the weight plate 14 or other stop surface designed into the dumbbell. The outer diameter of the flange portion 16 a is preferably less than that of the weight plate 14, but greater than that of the hub portion 16b. The outer diameter is preferably less than that of the weigh plate 14 because, as will be shown, it is not necessary to have the same or greater diameter and, more importantly, it is highly undesirable to have it protrude radially from the dumbbell so as to potentially cause damage to surrounding items that it strikes or be damaged itself if the dumbbell is dropped onto the floor or other surface.
The hub portion 16b of the sleeve 16 has an outer diameter sized to fit through the generally central through-opening 17 of incremental weight plate 18. Incremental weight plate 18 is magnetically secured to the abutting surface of the flange portion 16a by providing one or more appropriately oriented magnets in the flange and/or incremental weight plate. By way of example, reference is made to
When the incremental weight plate is made from a non-magnetically responsive material, one or more magnetically-responsive regions 34, 36 can be affixed to, or imbedded within, the incremental weight plate to interact with those of the flange and thereby magnetically secure the incremental weight plate on the dumbbell. For example, magnetic regions 30, 32 of the flange (
The orientation of the magnets 34, 36 of the incremental weight plate can be utilized to provide a feature by which the incremental weight plate can be easily detached from the dumbbell. Specifically the face of magnets 34, 36 abutting the flange 16a are provided with opposite polarities, as are the magnetic regions 30, 32 of the flange. For example, if magnets 34, 36 respectively have the north and south pole facing the flange, and the magnetic regions 30, 32 respectively have the south and north pole facing the incremental weight plate, the incremental weight plate will be securely mounted to the dumbbell when the flange's magnetic region 30 abuts the incremental weight plate's magnet 34 and the flange's magnetic region 32 abuts the incremental weight plate's magnet 36. Because of the magnetic attraction, removal of the incremental weight plate might be difficult, particularly since strong magnetically attractive forces are preferred in order to assure that the incremental weight plate does not slip from the dumbbell or move during the exercise movement. By rotating the secured incremental weight plate about the hub 16b on which it is mounted, however, and generally aligning the incremental weight plate's magnet 34 with the flange's magnetic region 32, the two will be caused to repel each other because of their now-abutting north poles. Similarly, the flange's magnetic region 30 will repel the incremental weight plate's magnet 36 owing to their abutting south poles. Consequently, the incremental weight plate will space itself from the flange, making its removal very easy.
Returning to
Alternatively, an axial sleeve having an externally threaded bolt-like protrusion can be utilized. As illustrated in
The sleeve 16 is also adaptable for use with adjustable dumbbells, both as an adapter to be used with pre-existing dumbbells, and as a component of an improved dumbbell. Adjustable dumbbells are known, for example, that have bars with externally threaded end sections. Dumbbells of this type utilize an internally threaded collar at each end of the dumbbell. Each collar is threaded onto the bar after the weight plates at that end of the bar has been mounted, and rotated so that it advances progressively towards the handle of the dumbbell until it secures the mounted weight plate(s) against the respective flange (or other plate-stopping surface).
As illustrated in
The sleeve 16″ is screwed into the bar 12″ until the flange 16a″ contacts the weight plate 14″ and captures it against the handle 13″. A surface feature on the sleeve, such as axially-extending slots 42, can be provided as a wrench-engaging surface to enhance the user's ability to securely tighten the sleeve onto the dumbbell. Moreover, the surface feature enhances the sleeve's grippability so that a user can more securely tighten the sleeve by hand if a wrench is not used, but the use of a wrench is highly preferred for security. Other surface features, such as axially-extending fiats or sleeves of polygonal cross-section, that can be readily gripped by a wrench or the human hand can be utilized as well. While it is recognize that the flange may be provided with wrench-accommodating surfaces as well, and it is intended that such surfaces be included within the scope of the invention. it is believed that the formation of such surfaces in the hub is more practical. As before, an incremental weight plate 18″ can then be mounted over the hub 16b″ of the sleeve, as desired, to be magnetically secured to the flange 16a″ whether or not the weight plate 14″ is magnetically responsive.
Returning to
Those of ordinary skill in the art will recognize that alternative means for releasably securing the incremental weight plate to the dumbbell can be used in place of the magents described above. For example, the flange portion of the annular sleeve and the incremental weight plate can be fit with complimentary strips of adhesive-backed Velcro® to reliably but releasably secure the incremental weight plate against movement on the hub portion during the exercise movement.
Although the present invention and its advantages have been described in detail, it should accordingly be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as will be defined by the appended claims.