Brushing – scrubbing – and general cleaning – Machines – Brushing
Reexamination Certificate
2002-03-01
2003-09-23
Chin, Randall E. (Department: 1744)
Brushing, scrubbing, and general cleaning
Machines
Brushing
C015S078000
Reexamination Certificate
active
06622336
ABSTRACT:
TECHNICAL FIELD
This invention pertains to ground sweeping devices. Specifically, this invention pertains to a rotary brush assembly, which in its preferred embodiment is an attachment to a skid steered vehicle or tractor.
BACKGROUND OF THE INVENTION
Rotary brush assemblies are used to sweep sand, snow, and other debris from sidewalks, roads or other ground surfaces. Configurations for rotary brushes are either transverse, where the brush axis of rotation is parallel to the ground, or vertical, where the brush axis of rotation is perpendicular to the ground. There are also single brush configurations and multiple brush configurations. The present invention deals primarily with a transverse single brush, but it would be clear to one skilled in the art that this invention could be applied to other brush orientations and multiple brush assemblies as well.
Because brush assemblies often weigh several hundred pounds, they are attached to and powered by traction vehicles. Frequently, the brush is attached to the front of a tractor or skid steer vehicle so the operator can see the brush and the ground at the same time and make adjustments to effectively clean the surface.
This invention addresses the problems of how to more effectively clean uneven surfaces, and how to minimize brush wear. A higher number of degrees of freedom in a brush assembly helps the brush conform better to uneven surfaces which makes cleaning more effective, and lessens brush wear. In addition to increasing the number of degrees of freedom, this invention describes novel ways to monitor and control movement of the brush within these degrees.
A degree of freedom in the motion of an object such as a brush assembly can be one of six types. There are three directions of linear motion and three types of rotational motion, each of which is a degree of freedom. Linear motion is non-rotational motion of an object along one of the three Cartesian coordinate axes, i.e. forwards/backwards, side to side, or up/down. Rotational motion is the spinning of an object about any one of the three Cartesian axes. For the purposes of this invention, the following terms will be used. The three linear degrees of freedom are described in common language terms such as forward/backward, up and down, and side to side. These linear directions will also be used to define axes of rotation for rotational motion. Rotation about the forward/backward axis will be called roll, rotation about the up/down axis will be called yaw, and rotation about the side to side axis will be called pitch.
Within the range of motion of any given degree of freedom, an object's position may either be controlled or free. For instance, in U.S. Pat. No. 5,732,781 a bucket attachment to a skid steer vehicle is rotatable about a “roll” axis as one of its degrees of freedom. In addition, the bucket rotation is controlled. The bucket attachment contains a hydraulic cylinder that allows the operator to choose an angle within the range of roll rotation to stop at. Once the operator chooses a position it is fixed until the operator makes further adjustments. In contrast, U.S. Pat. No. 5,426,805 and a commonly assigned pending patent application show rotary brushes that are also rotatable about a roll axis, but in these cases the rotation is not controlled. As the brush in U.S. Pat. No. 5,426,805 comes into contact with variations in terrain, the roll pivot joint allows the brush to rotate freely. Free joint motion is more desirable to accommodate changes in terrain because it allows the brush to conform to the terrain without requiring the operator to make numerous and frequent position adjustments.
U.S. Pat. No. 5,299,857 shows a rotary planer that is mounted on the front of a skid steered vehicle. The rotary planer in this prior art is moveable along the up/down linear axis, it is moveable along the linear side to side axis, and it is rotatable about the roll axis. All of these three degrees of freedom are operator controlled. Although controlled degrees of freedom are well suited to a planing operation where the objective is to remove surface variations, in a brushing application, surface variations need to be accommodated. When the roll degree of freedom on a rotary brush is fixed and an irregular slanted surface is encountered, the bristles at one end of the brush are excessively compressed, and at the other end of the brush the bristles may not contact the ground. This situation leads to the problems of excessive brush wear from the compressed bristles, and ineffective surface cleaning where the brush doesn't contact the ground.
The situation is also true of the up/down linear degree of freedom. Although the rotary implement in U.S. Pat. No. 5,299,857 can move along the up/down axis, it is controlled in this degree of freedom. In the case of a rotary brush, if a large bump is encountered, any joint allowing up/down motion must be a free joint. Otherwise the brush bristles will merely compress, which leads to excessive brush wear or uneven sweeping.
U.S. Pat. No. 4,811,442 addresses the issue of brush wear from encountering large uniform bumps. It shows a brush assembly where the brush is allowed to move up and down freely without over compressing the bristles. The solution in this prior art is to allow pitch rotation of the brush about a joint located near the tractor. A linkage then connects the brush frame to the pitch pivot joint. Because the brush in '442 is located far away from the pitch pivot joint, the rotational motion is along a small arc of a large radius, and is similar to up/down linear motion. The disadvantage of this design is that the brush must be located far away from the pitch pivot joint to achieve an effective range of motion. Brushes located farther away from the tractor tend to be cumbersome and hard to control.
Sometimes it is to the advantage of the operator to control one of the degrees of freedom. In the case of yaw, the angle that the brush is set at determines where the debris is swept. If this angle is not adjustable, the brush assembly will only be able to sweep to one side of the tractor. If the yaw pivot joint is not controlled, the angle will change unpredictably with changes in the surface being swept, and the operator will not be able to control where the debris goes.
U.S. Pat. No. 4,811,442 shows a brush assembly that is attached to a skid steer type vehicle where the yaw is controlled by means of a hydraulic cylinder. The disadvantage of this design is that it requires a connection to the hydraulic system on the skid steer vehicle and a separate control for the operator. These extra features are expensive and make the attachment of the brush assembly more time consuming.
SUMMARY OF THE INVENTION
The present invention includes a rotary brush assembly for use with a traction vehicle. The brush assembly includes a brush support frame and a rotary brush that is operatively connected to the brush support frame. The brush assembly also includes a roll pivoting joint permitting rotation of the frame about a first axis substantially parallel to the forward direction of vehicle travel when the brush support frame is in its normal or centered position. The brush assembly also includes a yaw pivoting joint permitting rotation of the frame about a second axis substantially perpendicular to the ground. The brush assembly also includes a linear sliding joint that allows the brush to rise and fall in a direction substantially perpendicular to the ground.
The brush assembly might include a rotary brush rotating about an axis of rotation substantially parallel to the ground. It might also include a roll pivoting joint that permits free movement of the frame about the first axis as the brush encounters uneven features, and a linear sliding joint that permits free movement of the frame up and down in a direction substantially perpendicular to the ground, wherein movement of the frame about the second axis of rotation is controlled by the operator. The yaw pivoting joint and the sliding joint might be coaxial. The sliding joint might
Chin Randall E.
Fulbright & Jaworski L.L.P.
The Toro Company
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