The invention relates generally to the field of carts, and particularly to mobile carts with multi-wheeled bases.
Mobile carts are employed in many industries, and may be used to carry a computer, monitor, display, or other electronic equipment; to provide a work surface, such as for a computer keyboard and mouse; and/or to provide portable storage, such as a tray or compartment. The overall weight of some mobile carts, particularly those equipped with electronic equipment and power supplies, may be an ergonomic issue. With an average weight exceeding 100 pounds, pushing a mobile cart can be tiring and cumbersome, especially for smaller users.
In the past, mobile carts have been equipped with four swivel casters or wheels, which permit the user to maneuver the cart around corners, or push it out of the way if necessary, but makes the cart difficult to steer. In particular, the momentum of the cart may be a problem if the cart is moved quickly, as the cart may become difficult to stop or turn. In addition, the carts are difficult to push in a straight line, as the four swivel casters may cause the cart to move slightly from side to side as it pushed, especially if the floors are uneven.
The maneuverability of a mobile cart can be improved by making two of the four casters ridged or non-swiveling. In this configuration, the mobile cart operates much like a shopping cart, and the user steers the cart by controlling the front end. This is not ideal, however, because it is still difficult to turn tight corners, and nearly impossible to pivot in place.
There is a need in the art, then, for a mobile cart that is easy to maneuver; a cart that can turn effortlessly and quickly, without a concern that the momentum of the cart will lead the cart astray. In addition, there is a need for a mobile cart that will move in a straight line when pushed, and will self-adjust so that the wheels stay in contact with the floor, either automatically, in response to the movement of the cart, or manually.
The invention provides a multi-wheeled base for a mobile cart. The base may include one or more swiveling, optionally locking, caster wheels and one or more non-swiveling traction wheels to improve the maneuverability of the cart by making it easier to steer and stop. The traction wheels may be manually-engaged traction wheels, which in one non-limiting example may be operated by a cam and lever. The traction wheels may also be automatically-engaged traction wheels operated by a motor and a threaded shaft, activated by a motion-sensitive sensor or by an on/off electrical switch or button.
The multi-wheeled base may comprise a base frame that is generally rectangular, and may include four protruding legs, one leg extending from and proximate each corner of the base frame. One swiveling caster wheel may be mounted to each of the protruding legs. If the base frame does not include the protruding legs, the swiveling caster wheels may be mounted to the base frame at the corners of the base frame.
The base frame is preferably configured to accommodate one or more optional battery cell housings and battery cells, in which case an electrical interconnect assembly is used to connect the battery cells and provide electrical connections for the mobile cart, including the electrical connections needed to power the automatically-engaged traction wheel.
One non-limiting embodiment of the manually-engaged traction wheel includes a traction wheel housing and a cam and lever wheel-positioning assembly. The traction wheel housing includes a wheel assembly sandwiched between two assembly plates, such that the wheel assembly may move up and down a short distance relative to the assembly plates. The up and down movement of the wheel assembly is controlled by the cam and lever assembly, and is guided and limited by elongated slots defined in the assembly plates. When the lever is in a first position, the cam and lever assembly is engaged, the wheel assembly is lowered, and the wheel of the wheel assembly touches the floor or ground. When the lever is moved up or down ninety-degrees from the first position, the cam and lever assembly is disengaged, the wheel assembly is raised, and the wheel is lifted off the floor or ground.
In a non-limiting embodiment, the automatically-engaged traction wheel includes a traction wheel housing and a motor and threaded shaft wheel-positioning assembly. The traction wheel housing includes a wheel assembly sandwiched between two assembly plates, such that the wheel assembly may move up and down a short distance relative to the assembly plates. The up and down movement of the wheel assembly is controlled by the motor and shaft assembly, and is guided and limited by elongated slots defined in the assembly plates. A Hall effect sensor is used to detect an “on/off” signal from a magnet embedded in the rotating wheel. As long as the Hall effect sensor detects the “on/off” signal from the magnet, the motor and the threaded shaft turn such that the wheel assembly is lowered, and the wheel touches the floor or the ground. When the Hall effect sensor stops receiving the “on/off” signal from the magnet, because the wheel is no longer rotating, the motor and the threaded shaft turn such that the wheel assembly is lifted, and the wheel is lifted off the floor or ground.
In an embodiment, mobile cart base comprises a base frame having a generally rectangular shape and a front frame member, a rear frame member, two opposing side members, and a center frame member coupled to the front frame member and the rear frame member, where the center frame member is generally parallel to the opposing side members and generally perpendicular to the front frame member and the rear frame member; four swiveling wheels mounted to the base frame proximate each of the four corners of the base frame; and a non-swiveling traction wheel mounted to the center frame member, where the traction wheel comprises a cam and lever assembly that is adapted to raise and lower the traction wheel relative to the base frame.
In another embodiment, a mobile cart base comprises a base frame having a generally rectangular shape and a front frame member, a rear frame member, two opposing side members, and a center frame member coupled to the front frame member and the rear frame member, where the center frame member is generally parallel to the opposing side members and generally perpendicular to the front frame member and the rear frame member; four swiveling wheels mounted to the base frame proximate each of the four corners of the base frame; and a non-swiveling traction wheel mounted to the center frame member, where the traction wheel comprises a motor and threaded spindle assembly that is adapted to raise and lower the traction wheel relative to the base frame.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
I. Mobile Cart Base
With reference to
As shown in
As shown in
As shown in
With reference to
As shown in
In a preferred embodiment, spring assembly 610 comprises a bushing 611, a spring 612, a retainer 613 and one more screws or fasteners 614 to couple retainer 613 to center frame member 140. Spring 612 is preferably a compression spring.
In a preferred embodiment, electrical interconnect assembly 620 comprises interconnect board 621, interconnect board housing 622, screws 623 to couple interconnect board 621 to interconnect board housing 622, and screws or fasteners 624 to couple interconnect board housing 622 to center frame member 140. In alternate embodiments, interconnect board 621 includes a connector (not shown) that is used to power an automatically-engaged traction wheel 1010, described in detail below.
As shown in
In an alternate embodiment, the base frame 105 may not include center frame member 140, battery cell compartments 510 and 520, and/or battery cells 710 and 720, and the manually-engaged traction wheel 990 may be mounted to either or both of the left and right frame members 108 and 109.
In one non-limiting embodiment, mobile cart base 800 may be used as the rolling base section for a mobile cart, such as mobile cart 8200 shown in
II. Manually-Engaged Traction Wheel
The details of manually-engaged traction wheel 990, shown previously in
As shown in
With reference to
Left wheel bracket 942 and right wheel bracket 943 each define an elongated slot, 946 and 947, respectively, through which bushing 913 is inserted and coupled to post 919, as shown in
When assembled, wheel assembly 940 defines a top member 966 and a notch 950. As shown in
The wheel assembly 940 is lowered or raised by lever 923. When lever 923 is in a first position, for example a generally horizontal position, as shown in
III. Automatically-Engaged Traction Wheel
The details of automatically-engaged traction wheel 1010 are shown in
As shown in
With reference to
Left wheel bracket 1022 and right wheel bracket 1023 each define an elongated slot, 1061 and 1062, respectively, through which bushing 1036 is inserted and coupled to 1039, as shown in
Motor and shaft wheel-positioning assembly 1040 is shown in
In a preferred embodiment, automatically-engaged traction wheel 1010 is motion sensitive. Circuit board 1072 includes a Hall Effect sensor 1082 that controls motor 1041. Hall Effect sensor 1082 responds to a small magnet 1083 embedded in wheel 1021, as shown in
When wheel 1021 is not spinning, the Hall Effect sensor 1082 does not detect the “on/off” signal from magnet 1083, and motor 1041 turns threaded shaft 1042 to a first position such that wheel assembly 1020 is raised relative to the traction wheel housing 1030 and wheel 1021 is no longer in contact with the floor or other surface. When wheel 1021 is spinning, the Hall Effect sensor 1082 detects the “on/off” signal from the magnet 1083, and motor 1041 turns threaded shaft 1042 to a second position such that wheel assembly 1020 is lowered relative to the traction wheel housing 1030 and wheel 1021 is in contact with the floor or other surface.
Circuit board 1072 also includes a vibration sensor chip 1081. When the mobile cart is in motion, the vibration sensor chip 1081 causes motor 1041 to turn threaded shaft 1042 so as to lower wheel assembly 1020, such that wheel 1021 is in contact with the floor or other surface.
In an alternate embodiment, automatically-engaged traction wheel 1010 is operated by an on/off switch or button, which may be located on the mobile cart base 800, or the upper working section 8210 or the intermediate section 8230 of the mobile cart 8200.
Motor 1041 receives power from the on-board battery cells 710 and 720 through interconnect board 621, shown in
The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/308,965, entitled “MOBILE CART BASE WITH TRACTION WHEEL,” filed on Feb. 28, 2010, and is a continuation-in-part and claims priority to co-pending U.S. patent application Ser. No. 12/418,338, entitled “MOBILE CART,” filed on Apr. 3, 2009, which itself claims priority to U.S. Provisional Patent Application Ser. No. 61/074,170, entitled “BEDSIDE MEDICATION DELIVERY CART,” filed on Jun. 20, 2008. The entire contents of all three priority applications are expressly incorporated by reference herein.
Number | Name | Date | Kind |
---|---|---|---|
2563919 | Christensen | Aug 1951 | A |
2935331 | Ledgerwood | May 1960 | A |
3391256 | Nawman | Jul 1968 | A |
3715148 | Beals | Feb 1973 | A |
3744282 | Hemphill | Jul 1973 | A |
3910659 | Peterson | Oct 1975 | A |
4005279 | Richter | Jan 1977 | A |
4453692 | LeDoux et al. | Jun 1984 | A |
4471409 | Dittrich | Sep 1984 | A |
4696449 | Woo et al. | Sep 1987 | A |
4750204 | Bartley et al. | Jun 1988 | A |
4937860 | Smith | Jun 1990 | A |
4946120 | Hatcher | Aug 1990 | A |
5052651 | Guddee | Oct 1991 | A |
5085395 | Frater et al. | Feb 1992 | A |
5595074 | Munro | Jan 1997 | A |
5645261 | Glynn | Jul 1997 | A |
5673628 | Boos | Oct 1997 | A |
5709110 | Greenfield et al. | Jan 1998 | A |
5769369 | Meinel | Jun 1998 | A |
5794463 | McDaid | Aug 1998 | A |
5836183 | Derman | Nov 1998 | A |
5859762 | Clark et al. | Jan 1999 | A |
5941180 | Becker | Aug 1999 | A |
6021720 | Boos et al. | Feb 2000 | A |
6216499 | Ronberg et al. | Apr 2001 | B1 |
6237375 | Wymer | May 2001 | B1 |
6256812 | Bartow et al. | Jul 2001 | B1 |
6443417 | Galant | Sep 2002 | B2 |
6491268 | Channer et al. | Dec 2002 | B1 |
6491276 | Belliveau | Dec 2002 | B1 |
6585212 | Carnevali | Jul 2003 | B2 |
6711921 | Yang | Mar 2004 | B1 |
6763690 | Galant | Jul 2004 | B2 |
7007912 | Guiliani et al. | Mar 2006 | B1 |
7315443 | Allen | Jan 2008 | B2 |
20040007651 | Williams et al. | Jan 2004 | A1 |
20040177658 | Mitchell | Sep 2004 | A1 |
20090315287 | Rossini | Dec 2009 | A1 |
Number | Date | Country | |
---|---|---|---|
20110140381 A1 | Jun 2011 | US |
Number | Date | Country | |
---|---|---|---|
61308965 | Feb 2010 | US | |
61074170 | Jun 2008 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12418338 | Apr 2009 | US |
Child | 13035481 | US |