Abrading – Frame or mount – Portable abrader
Reexamination Certificate
1999-11-12
2001-05-15
Hail, III, Joseph J. (Department: 3723)
Abrading
Frame or mount
Portable abrader
C451S351000, C451S353000, C015S049100, C144S117100
Reexamination Certificate
active
06231432
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to floor treatment machines that have rotating heads for the treatment of floor surfaces. More particularly, the present invention relates to a floor treatment machine with a torque overload protection device.
BACKGROUND OF THE INVENTION
Floor treatment machines for polishing, grinding, sanding or otherwise treating surfaces such as concrete or wood floors are well known. U.S. Pat. No. 5,514,027, describes an example of such a floor treatment machine. The floor treatment machine has a handle and a housing containing a motor that rotates a floor treatment head.
In use, the head of the machine rotates on the floor surface that is being treated. The head has twelve pin-type abraders mounted to a disk. When the disk rotates, the abraders sand the surface of the floor. However, the disk can abruptly stop if the abraders contact an obstruction, such as a protrusion on an uneven floor. In stopping abruptly, a torque is applied to the linkage between the motor and the stationary head. This torque can break the linkage or otherwise damage the motor of the floor treatment machine.
U.S. Pat. No. 2,785,424 describes another floor treatment machine that has a centrifugal clutch. While the clutch of this machine is generally effective and is intended to allow the machine's motor to remain spinning when the machine's head hits an obstruction, it has certain drawbacks. In particular, as described at column
9
, line
50
, the centrifugal clutch is relatively complicated and therefore can be less reliable and more expensive to manufacture and to maintain.
Accordingly, there exists a need for a floor treatment machine with a torque overload protection device that is reliable and inexpensive to manufacture. The present invention solves these problems and provides further related advantages.
SUMMARY OF THE INVENTION
The present invention relates to a floor treatment machine with a torque overload protection device that is reliable and inexpensive to manufacture. A primary advantage of the present invention is associated with improved protection for drive linkage components. The torque from an overload can damage or break individual components of the drive linkage of the floor treatment machine. By limiting the maximum amount of torque applied to the drive linkage, the the floor treatment machine is less likely to be damaged. In addition, the components described below are relatively simple and therefore are less expensive to manufacture and are believed to provide greater reliability.
More particularly, and by way of example only, the floor treatment machine may have a body, a rotating drive linkage, a spinning head for treating the floor surface and a torque limiter assembly. The rotating drive linkage projects from the body and is positioned along a predetermined axis of rotation. The floor treatment head is configured to attach to the drive linkage and the torque limiter assembly is mounted between the floor treatment head and the drive linkage. The torque limiter assembly includes a housing that has a cavity holding two plates.
The first plate is operatively connected to the drive linkage and has a surface positioned normal to the axis of rotation. The second plate is operatively connected to the head and has a surface in opposed alignment with the surface of the first plate. The surface of the second plate is configured to engage the surface of the first plate. The first and the second plate are biased toward each other and are mounted for relative movement away from each other. The surface of the first plate and the surface of the second plate are configured to cooperatively force the plates away from each other upon the application of a torque to the plates.
In a more detailed aspect of the present invention, a spring mounted within the cavity may be used to bias the plates away from each other. In yet another detail, the first and second plates may engage each other via one or more aligned teeth and notches. The plates may be configured with six aligned teeth and notches. In another detailed aspect of the invention, the face of each tooth and notch engage each other in a plane at 45° from the surface of the first plate. This angle of engagement allows the tooth and notch to slip when a torque is applied to the plates, thereby overcoming the bias and moving the plates away from each other to a position where the tooth and notch are disengaged. When the tooth and notch are disengaged, the plates can rotate with respect to each other to relieve the torque load on the drive linkage.
In yet more detailed aspects of the present invention, the surfaces of the plates may be hardened to decrease wear and/or the bias forcing the plates together may be adjustable. Wave springs may be used to provide the bias force. In yet further detailed aspects, the floor treatment machine can include a mechanism that locks the plates together to override the torque limiter assembly components. In particular, one, two, or more tabs can be pivotably mounted within the housing cavity for rotation between a first and a second position. In the first position, the tab does not obstruct the movement of the plates and in the second position the tab does obstruct the movement of the plates away from each other, thereby locking them together.
The invention also is embodied in a floor treatment head with a built-in torque limiter assembly having the plates described above. Because it is attached to the floor treatment head, the benefits of the torque limiter assembly can apply to any floor treatment machine configured to engage the head. The detailed features described above may be included in the floor treatment head.
Another advantage of the present invention is associated with the improved safety. Since the torque limiter assembly disengages the head from the drive linkage, the floor treatment machine is less likely to spin or otherwise move erratically if the head suddenly stops spinning because of a floor surface obstruction.
Still another advantage of the present invention is associated with a loud noise that occurs when the first and second plates disengage. This noise immediately notifies the user of an excess torque situation. After the user remedies the overload, the plates in the torque limiter assembly automatically re-engage.
Other features and advantages of the present invention shall become apparent from the following description of the preferred embodiment, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the inventions.
REFERENCES:
patent: 2785424 (1957-03-01), McMaster et al.
patent: 3552070 (1971-01-01), Reiss
patent: 3583017 (1971-06-01), Davis
patent: 4138804 (1979-02-01), Thielen
patent: 4757566 (1988-07-01), Field et al.
patent: 4784519 (1988-11-01), Artzberger
patent: 5514027 (1996-05-01), Pearlman
patent: 5645365 (1997-07-01), Malish et al.
Power Transmission Components, Mayr Power Transmission Inc., Jan., 1998.
OPTI Torque Torque Limiters, Mayr Power Transmission, Inc., Oct., 1998.
Dalton Catalog No. 989—OSD Overload Safety Devices Torque Limiters—Couplings, Dalton Gear Company, Inc., date unknown.
Boston Centric Clutch Products, Boston Gear, Inc., 1998.
Torq-Tender Mechanical Torque Limiters, Zero-Max, Inc., 1996.
SePac, Inc. Clutches and Brakes brochure, 1999.
Smartflex brochure, Mayr Corp., undated.
Jackola Michael A.
Peterson Clay
Berry Jr. Willie
Brueggemann James R.
Hail III Joseph J.
Pearl Abrasive Company
Sheppard Mullin Richter & Hampton LLP
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