Patent Application
20080127451
The inventions described and claimed herein relate generally to casters which include tip resisting features. More specifically, the inventions described herein incorporate a caster with a forwardly projecting kickstand for an outdoor barbecue grill for complying with CSA Standard No. 1.6, Section 2.18.4 (ANSI Z21.58).
The Canadian Standards Agency (“CSA”) instituted a standard which mandates that outdoor barbecue grills must be able to resist tipping over when tipped in any direction at an angle of 15°. To satisfy this standard, many manufacturers have employed means to lower the center of gravity of the grill or to move the base contact point outward, so that the center of gravity stays inside of the base contact point when tipped 15°. While these methods have been successfully used to satisfy the CSA standard, there are substantial drawbacks to this approach.
A first method currently used to lower the center of gravity is to utilize counterweights which are placed low on the barbecue grill. Obviously, this method substantially increases the overall weight of the barbecue grill. In some cases, the counterweights make the grill unwieldy, not only to deliver to the customer, but in actual use by the customer. Most barbecue grills are intended to be movable from one location to another and some grills are intended to be fully portable. Each added pound frustrates these purposes, since it makes the grill hard to push and hard to lift. Moreover, the increased weight of the barbecue grill not only increases the manufacturing cost for the grill, but also increases the shipping cost.
Another method used by manufacturers is reducing the weight of the cooking chamber. While this solution may aid in lowering the center of gravity, at the same time it reduces the quality and effectiveness of the barbecue grill. First of all, cooking chambers are typically fabricated out of thick walled metal to withstand the heat generated by the barbecue grill. Furthermore, most customers demand a solidly built barbecue grill which will be capable of withstanding time and the elements. Reducing the wall thickness may lower the center of gravity, but it would also reduce the perceived quality of the grill and may cause the grill to degrade faster.
Reducing the volume of the cooking grid, an internal component of the cooking chamber, is also a potential method for lowering the center of gravity. However, it is likely that a reduction in the volume of the cooking grd will substantially degrade the functionality of the grill. Many users employ a cooking technique called searing. Searing involves subjecting meat to a very high heat, sometimes just for a short period of time. Searing is generally most effective when the cooking grid is provided with a large volume, such that the grid is able to store great amounts of energy. In this manner, the grid is able to transfer such heat to the meat quickly, without a substantial reduction in temperature. As such, reducing the volume of the cooking grid with negatively impact a grill's searing capabilities.
Another method used in the art to prevent tipping is to increase the depth of the grill assembly. Increasing the depth of the grill moves the base contact point outward such that the center of gravity will not bear over the base contact point when the grill is tipped 15°.
The various embodiments of the present inventions not only provide a satisfactory means for complying with the CSA standards, but also do not suffer from the above-mentioned problems of the prior art. The preferred grill of the present invention includes a tip-resisting caster, which counteracts a moment of a barbecue grill with respect to a caster which may be present when the grill is placed in a tipped condition. By incorporating the tip-resisting caster of the present invention into the grill design, the grill manufacturer need not take steps to lower the grill center of gravity, by either reducing the weight of the cooking chamber or by adding counterweights.
The preferred tip resisting caster of the present invention is in many ways similar to prior art casters, in that it generally comprises a chassis, a connector for connecting to an object (i.e. barbecue grill), wheels, and a wheel lock. The connector is preferably a post or the like, although it could be a flange or a bracket. The wheels are preferably connected to the chassis along a rotational axis (i.e. axle), whereby the rotational axis is offset from the post. In this manner, the wheels will trail behind the post regardless of the direction in which the barbecue grill is pushed.
Where the preferred tip-resisting caster differs from the prior art is with respect to a tip support which projects from chassis, away from the post in a direction opposite from the rotational axis of the wheels. Accordingly, the tip support will almost always point in the direction of travel of the barbecue grill. The tip support is adapted to contact a horizontal surface when a barbecue grill is tipped approximately 15°. In this manner, the tip support presses against the horizontal surface thereby preventing rotation of the barbecue grill and providing a counteracting moment, in compliance with the CSA standards.
These and other features, aspects, objects, and advantages of the inventions described and claimed herein will become better understood upon consideration of the following detailed description, appended claims, and accompanying drawings where:
It should be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the inventions described and claimed herein or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the inventions described herein are not necessarily limited to the particular embodiments illustrated herein.
Like reference numerals will be used to refer to like or similar parts from figure to figure in the following description of the drawings.
Referring first to
Referring generally to
The preferred chassis 12 of the caster 10 can be characterized as the main support structure or frame for the caster 10, whereby each component of the caster 10 is generally connected directly to the chassis 12, although such a configuration is not necessary. There are preferably two wheels 20, 22 which are positioned on opposite sides of the chassis 12 and are connected to the chassis 12 along at least one axle 24, the axle 24 defining a rotational axis, which allows the wheels 20, 22 to rotate. Note that while the caster 10 is shown with two wheels 20, 22, the invention is not limited as such; more or less wheels 20, 22 may be sufficient. It is also contemplated that the caster 10 can comprise one axle 24 where all wheels 20, 22 are interconnected, or can comprise a separate axles 24, where each wheel 20, 22 moves independently of one another. The preferred wheel lock 30 of the present invention includes a lever or tab which prevents rotational movement of the wheels when pressed. Although the wheel lock structure is not described in detail herein, structure for locking caster wheels are well known in the art and need not be repeated herein. The connector 40 preferably upwardly projects from the chassis 12 and includes means for connecting the caster 10 to the barbecue grill 2. While the connector 40 can be any type of connector known or unknown in the art, including a flange and a bracket, the connector 40 is preferably a male connector such as post 40 (or prong or stem or the like) which is adapted to mate with a female connector (not shown) on the barbecue grill 2. This configuration could be reversed, however, wherein the connector 40 is a female connector which is adapted to mate with a male connector on the barbecue grill 2. The preferred connector 40, a post, preferably includes a retaining ring 42 which is adapted to lock the post 40 in engagement with the female connector. The connector 40 supports a load (i.e. the grill cart 2) along a longitudinal axis 44, whereby the weight of the load bears down on the caster 10 along the longitudinal axis 44.
The tip support 50 forwardly projects from the chassis and, preferably, the tip support 50 forwardly projects from the longitudinal axis 44 of the caster 10 as depicted in the figures. The tip support 50 is adapted to counteract a rotational moment which may be present when the barbecue grill 2 is in an inclined orientation. The tip support 50 does this by contacting a ground surface 64 when the grill 2 is inclined to a predetermined angle relative to the ground surface 64, thus preventing further rotation. This concept is more easily explained with reference to
The tip support 50 of the present invention can be generally characterized as a kickstand 50, whereby the kickstand 50 projects from the caster 10 towards a front side of the caster 10 and whereby a line drawn tangent with both the wheel and the kickstand is offset from a horizontal surface 64 by less than 15° (see Angle A). Accordingly, the tangent line is also offset from the longitudinal axis 44 by at least 75° (see Angle B), the longitudinal axis being generally parallel with vertical when the grill 2 is placed on a horizontal surface. Although Angle A is shown at approximately 15° to prevent tipping when the grill is inclined to 15°, it is contemplated that Angle A can vary depending upon the desired tip resistance. For instance, if a tip resistance is desired at 10°, to include additional safety margin or to comply with some other standard or requirement, the tip support 50 could be redesigned such that Angle A is approximately 10°.
Preferably, the tip support 50 includes a support surface 52 which is generally aligned with the line drawn tangent with the wheel 20, 22 and the kickstand 50. The preferred support surface 52 generally distributes the weight of the grill 2 to prevent breakage and/or to prevent significant displacement of the kickstand of the tip support 50 during the tip test and actual tipping conditions. The support surface 52 has a front edge 54 which preferably extends a distance D from the longitudinal axis, a distance which is preferably equal to or greater than the distance C. Furthermore, the support surface 52 has a rear edge 56 which is distanced slightly above the horizontal surface (i.e., when the grill 2 is not tipped) to provide clearance for caster 10 to easily roll over small pebbles and the like.
Although the inventions described and claimed herein have been described in considerable detail with reference to certain preferred embodiments, one skilled in the art will appreciate that the inventions described and claimed herein can be practiced by other than the preferred embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein.
