Abstract:
A safety apparatus for a tool driven by a motor removes motor power under certain circumstances. The tool includes a housing moveable over a ground surface for mounting the tool, and a ground-engaging member moveable relative to the housing and disposed to follow the ground surface as the housing moves over same. The apparatus further includes a sensor for measuring the relative position of the housing relative to the ground engaging member. Motor control apparatus selectively stops the motor upon the ground-engaging member and the housing reaching a predetermined relative position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This is a regular application filed under 35 U.S.C. § 111(a) claiming priority, under 35 U.S.C. § 119(e)(1), of provisional application Ser. No. 60/323,239, previously filed Sep. 19, 2001 under 35 U.S.C. § 111(b). 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to the field of cutting and mulching equipment. More specifically, the present invention relates to improved operator safety in the use of rotary brush cutters and mulchers.  
       BACKGROUND OF THE INVENTION  
       [0003]     Cutting and mulching equipment is often used to cut away and/or clear brush including tall grass, plants, weeds, shrubs, wood chips, branches and the like. A common method for clearing brush involves a rotary brush cutter. Such a cutter has a blade that rotates in a plane generally parallel to the ground such that it generally uniformly cuts the brush.  
         [0004]     A brush cutter may be mounted on a tractor loader(Bobcat) or other such surface loading machinery or equipment. The brush cutter is mounted generally on the front of a machine or cab such that the brush cutter clears a path for the operator and equipment on which the brush cutter is mounted.  
         [0005]     A brush cutter may pose a risk of injury to an operator. A common problem occurs where an object is thrown from the cutting area of the brush cutter. The object may be a twig, a rock, or any other object that may pose a risk to an operator. There is a potential that such an object could hit an operator and cause injury. This problem is more pronounced when the rear portion of the brush cutter is raised off the ground with respect to the front portion, the rear portion being the portion nearest the operator.  
         [0006]     It is thus preferable that the brush cutter have a protective mechanism, such as an automatic shut-down mechanism, for when the brush cutter is raised to a dangerous height off of the ground.  
         [0007]     One mechanism in the prior art involves a set of rollers positioned at a rear portion of a brush cutter. These rollers are heavy so that they maintain contact with the ground. If the brush cutter is raised to a predetermined height, the rollers will drop down with respect to the brush cutter housing and cause the automatic shut-off mechanism to be actuated. A problem with this apparatus is that the rollers may cause an unnecessary shut-off if the brush cutter travels over a hole or crevice area that causes the rollers to drop down to the predetermined shut-off distance.  
         [0008]     A similar problem can occur when the brush cutter travels over a log. The rollers will drop down once they have rolled over the log, thus unnecessarily implementing operation of the shut-off mechanism.  
         [0009]     Another problem with this mechanism is that it adds significant weight to the brush cutter, thus limiting the vast majority of cabs that can carry the weight of the shut-off mechanism.  
         [0010]     Another mechanism in the prior art involves the use of an apparatus wherein a shut-off mechanism is initiated based on the difference between the height of the brush cutter with respect to the height of a cab. This apparatus includes a chain having a first end bolted to the brush cutter and a second end secured to a chassis of the cab, to thus limit the height to which the brush cutter can be lifted off of the ground with respect to the cab. A problem with this mechanism is that the brush cutter may be located over an inclined surface with respect to the cab, thus unnecessarily initiating the shut-off mechanism.  
         [0011]     Another problem with these prior art mechanisms is that they lack shut-off devices that extend along the entire length of the side of the brush cutter to prevent debris from escaping through the sides of the brush cutter. Also, these mechanisms can become caught on the ground and other debris during operation, requiring the operator to shut down the machine and clean them off. Another problem with these mechanisms is that they are independent of the electrical mechanism, or motor, that runs the brush cutter. Thus, the safety mechanisms may be removed from the brush cutter without affecting operation. For example, the chain or rollers may be removed from the brush cutter and the brush cutter will still be able to operate, thus making the effectiveness of the safety mechanism moot.  
         [0012]     The present invention provides for an improved brush cutter that addresses these shortcomings.  
       SUMMARY OF THE INVENTION  
       [0013]     The present invention relates to improvements in safety features for a brush cutter. The invention includes a protection barrier on the sides of a brush cutter such that objects are prevented from being impelled from the brush cutter toward the operator as the brush cutter passes over the objects. The present invention further includes an emergency stop system, wherein the brush cutter is automatically shut off when the rear portion of the brush cutter is raised to a dangerous height off the ground.  
         [0014]     The brush cutter has a back end that is mounted to a drive vehicle, a front end opposite the back end, and two sides. The protective barrier comprises a side panel positioned outwardly of the sides of the brush cutter so as to prevent objects over which the brush cutter passes from being impelled out the sides of the equipment. Each side panel has a front end in the direction of the front end of the brush cutter and a back end in the direction of the back end of the brush cutter. The side panel front end has a hole proximate a hub, and the side panel back end has a slot extending generally vertically or vertically but slightly arcuately. The front end of the brush cutter structure has a pivot shaft that extends through the hub of the side panel. The side panel is able to pivot about the pivot shaft such that the back end of the side panel can pivot upwardly or downwardly with respect to the pivot shaft. The back end of the brush cutter structure has a slot rider that extends through the slot in the side panel. Thus, the side panel may pivot upwardly until the bottom of the slot engages the rider, and the side panel may pivot downwardly until the top of the slot engages the rider.  
         [0015]     In operation, if the rear portion of the brush cutter becomes elevated, the back end of the side panel will pivot downwardly relatively. The side panel then prevents objects from being impelled out the side of the brush cutter, wherein the bottom portion of the side panel extends below the bottom of the brush cutter structure. As the rear portion of the brush cutter is leveled, the back end of the side panel will pivot upwardly relatively.  
         [0016]     The emergency stop feature is achieved by employment of a system that shuts off the brush cutter motor when the rear portion of the brush cutter structure is elevated beyond a predetermined height. A hydraulic switch is employed such that, when the rear portion of the brush cutter motor is elevated, the hydraulic switch is depressed causing the motor to shut off.  
         [0017]     An embodiment of the emergency stop system comprises a hydraulic cylinder secured to the brush cutter structure. The cylinder has a piston end extending toward the back of the brush cutter. The piston end is secured to a pivoting elbow. The pivoting elbow has a first joint pivoting about the piston end, a second joint pivoting about a lower portion of the brush cutter structure, and a third joint pivoting about the side panel.  
         [0018]     The arm has a first joint that is connected to the third joint of the elbow and is able to pivot at that joint. The arm has a second joint that is connected to a middle portion of the side plate.  
         [0019]     The hydraulic piston acts to force the side plate downwardly. The downward force is supplied by the piston to the first joint of the elbow and interacts with the arm to force the side plate downwardly.  
         [0020]     A shut-off valve is positioned adjacent the back of the elbow portion of the pivoting elbow. The shut-off valve has a shaft extending therefrom toward the side panel. A yoke extends from the shaft. A pin extending from the side panel is able to engage the yoke to initiate the shut-off valve by rotating the shaft. A pin is set at a predetermined position on the side panel such that the shut-off valve is actuated only when the side panel moves downwardly a predetermined distance with respect to the housing.  
         [0021]     The shut off height and shut off time are adjustable. Adjusting the shut off time may be beneficial to allowing the operator to raise the rotary brush cutter off the ground for a short time without having it shut off. Also, once the motor is shut off, the operator may not turn it on again until the brush cutter has been lowered to the ground and the hydraulic flow has been reversed to reset the system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a side view of the present invention in a first configuration;  
         [0023]      FIG. 2  is a side view of the invention from  FIG. 1  in a second configuration;  
         [0024]      FIG. 3  is a perspective view of the present invention with some parts cut away;  
         [0025]      FIG. 4  is a side view of the present invention in the first configuration with some parts cut away;  
         [0026]      FIG. 5  is a side view of the present invention in the second configuration with some parts cut away; and  
         [0027]      FIG. 6  is a perspective view of the present invention with some parts cut away. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]      FIGS. 1 and 2  illustrate one embodiment of the present invention. A brush cutter attachment  10  is shown attached to the front of a cab  50 . The brush cutter attachment  10  may be used to cut brush such as plants, grass, weeds, branches and the like. The cab  50  provides means for an operator to steer and advance the brush cutter attachment  10  over a surface to be cleared by the attachment  10 .  
         [0029]     The brush cutter attachment  10  is shown as having a housing  20  and a side panel  30  moveably secured to the housing  20  in a pivotal fashion. A biasing assembly  40  extends from the housing  20  to the side panel  30  urging the side panel  30  downwardly with respect to the housing  20 .  
         [0030]     The attachment  10  is operated by a motor. A shut-off valve  42  is mounted to the housing  20  and is activated to shut off the motor when the side panel  30  extends downwardly a predetermined distance with respect to the housing  20 . As shown in  FIG. 1 , the side panel  30  is biased to contact the cutting surface as the housing  20  travels over the surface. In this illustration, operation of the shut-off  42  valve will not occur and the motor will continue to operate.  
         [0031]     As shown in  FIG. 2 , the housing  20  may be movable a predetermined distance above the surface to be cleared. This will render the side panel  30  extending downwardly a predetermined distance relative to the housing  20 , thus initiating the shut-off valve  42  and shutting off the motor.  
         [0032]     The housing  20  has a pair of sidewalls  22 , a front wall  24 , a rear wall  26 , and a cover  28 , for housing a cutting blade. The cutting blade rotates about a shaft extending through the cover  28  toward the cutting surface. The blade rotates, it is intended, substantially parallel to the cutting surface at a predetermined height above that surface. The cutting blade is rotated by the motor. The motor is mounted on a top portion of the housing cover  28 , within a motor casing.  
         [0033]     The side panel  30  is moveably secured to the housing  20 . The side panel  20  is biased downwardly with respect to the housing  20  for preventing debris from projecting from beneath the housing  20  and possibly causing injury to the operator or to a bystander. The side panel may  30  extend along the entire fore-and-aft length of the brush cutter  10 .  
         [0034]     The side panel  30  is, at a front location  32 , pivotally connected to the housing  20 . The front portion  32  has an aperture  34  for pivotally securing the side panel  30  to the housing  20 . A locking bolt  36  may be extended through the aperture  34  to maintain the side panel  30  adjacent the housing  20 . A neck  37  of the bolt  36  may extend through the aperture  34  and into a securing portion of the housing  20 . The head of the bolt  36  may extend to an outer surface  31  of the side panel  30  for maintaining the side panel  30  adjacent to the housing  20 .  
         [0035]     The side panel  30  has a back portion  38  that pivots about the aperture  34 . The back portion  38  has an arcuate slot  39  for receiving a guide member  35 . The guide member  35  extends from the housing  20  and through the slot  39 . The guide member  35  may have a head that extends through to an outer side  31  of the side panel  30 . The head portion may be wider than the slot  39  to maintain the side panel  30  adjacent the housing  20 . The slot  39  may have a radius of curvature for allowing the side panel  30  to pivot. The side panel  30  is able to pivot about the locking bolt  36  until the guide member  35  contacts an upper limit or lower limit of the slot  39 .  
         [0036]     The panel  30  has a top side  52  and a bottom side  54 . The top side  52  may converge toward the bottom side  54  as it progresses toward the front  32  of the side panel  30 . A substantial length of the bottom side  54  of the side panel  30  is linear for contacting the cutting surface.  
         [0037]     In operation, as the brush cutter  10  is advanced over a surface, the side panel can pivot about the locking bolt  36 . For example, if the housing  20  is substantially close to the cutting surface, the side panel  30  will be centered such that the guide member  35  is spaced from the upper limit  56  and lower limit  58  of the slot  39 . If the housing  20  becomes raised above the cutting surface, the side panel  30  moves downwardly toward the cutting surface such that the guide member  35  becomes located at the upper limit  56  of the slot  39  and the bottom side  54  of the side panel  20  extends below a lower portion  21  of the housing  20 .  
         [0038]     The housing  20  has a cover panel  28  and a pair of sidewalls  22  for housing the cutting blade. The housing  20  has a front portion  25  that is angled upwardly with respect to the lower portion  21  of the housing  20 . The front portion  25  allows for brush to be received within the housing  20  in order to be cut by the blades. The housing  20  has a rear portion  27  for connection to the cab  50 . By connecting to the cab  50 , the housing  20  may be directed over the cutting surface by the operator of the cab  50 . A motor used for rotating the blade may also be connected to, and operable from, the cab  50 . The motor provides a torque force to a blade shaft for rotating the blade.  
         [0039]      FIGS. 3 through 6  illustrate a biasing mechanism  40  mounted for biasing the side panel  30  downwardly with respect to the housing  20 . A shut-off valve  42  is also secured to the housing  20 . The shut-off valve  42  works in tandem with the biasing mechanism  40  such that, when the side panel  30  is fully extended downwardly, the shut-off valve  42  will be switched so as to shut-off the motor to the rotatable blade, thus stopping the blade from being rotated and preventing possible injury to the operator.  
         [0040]     Turning now to  FIGS. 3-6 , the biasing mechanism  40  includes a cylinder  44  and piston  46  assembly secured to the top portion  28  of the housing  20 . The cylinder  44  and piston  46  assembly may be hydraulic, as shown. The piston  46  has a working end  47  pivotally connected to a first end  62  of a bell crank  60 . A second end  64  of the bell crank  60  is pivotally attached to the side panel  30  via a connecting arm  66 . The connecting arm  66  has a first end  67  pivotally connected to the second end  64  of the bell crank  60  and a second end  68  pivotally connected to the side panel  30 . The bell crank  60  has an elbow  61  that is pivotally secured to the housing  20 . As shown, the elbow  61  is pivotally connected to a mounting member  29  extending from the top portion  28  of the housing  20 . The elbow  61  is positioned proximate the shut-off valve  42 .  
         [0041]     The shut-off valve  42  is secured to a motor casing  23  extending above a top portion  28  of the housing  20 . The shut-off valve  42  has a rotatable shaft  70  extending in a direction toward the side panel  30 . The shaft  70  has a first end  71  for receiving a pin  33  extending from the side panel  30 . A yoke  72  is positioned at the first end  71  for engaging the pin  33  such that, as the pin  33  is received within the yoke  72 , the shaft  70  will be rotated so as to initiate action by the shut-off valve  42  and shut-off the motor by shutting off the hydraulics to the motor.  
         [0042]     The shaft  70  has a lift limit switch  74  that will rotate with the shaft  70  such that, when the shaft  70  is rotated, the limit switch  74  will extend upwardly.  
         [0043]     The shut-off valve  42  may have a timer such that the valve  42  may be rotated for a predetermined period of time before the shut-off valve  42  initiates shutting down the motor. Thus, if the yoke  72  is removed from a position receiving the pin  33  prior to reaching the predetermined period of time, the motor will not be shut off.  
         [0044]     The side panel  30  has a bracket  53  for mounting the pin  33  to the side panel  30 . The pin  33  extends inwardly from the side panel  30  for engaging the first end  71  of the shaft  70 . More specifically, the pin  33  extends from an inner portion of the side panel  30  for engaging the receiving portion  73  of the yoke  72 . The bracket  53  may be adjustable such that the height at which the housing  20  must be raised with respect to the side panel  30  at which the shut-off valve  42  will be engaged, may be adjusted.  
         [0045]     In operation, the motor will rotate the blade and the operator may steer the cab  50  over a cutting surface. As the brush cutter  10  travels over the cutting surface, the piston  46  is biased in the direction of the cylinder  44 , thus biasing the side panel  30  downwardly with respect to the housing  20  and towards the cutting surface. The elbow  61  will pivot so as to distend the connecting arm  66  downwardly toward the cutting surface. The side panel  30  is able to pivot about the front portion  32  locking bolt  36  and move upwardly and downwardly with respect to the housing  20  as the brush cutter  10  moves over ground.  
         [0046]     When the housing  20  is lifted a predetermined distance above the cutting surface, the side panel  30  will extend downwardly such that the engaging pin  33  will engage the yoke  72  at the first end  71  of the shaft  70  of the shut-off valve  42 . The engaged yoke  72  will cause the shaft  70  to rotate, initiating the shut-off valve  42  to shut-off the hydraulics to the motor, and thus shutting down the blade from rotating. The lift limit switch  74  extends upwardly from the housing.  
         [0047]     The operator may restart the motor by returning the brush cutter  10  to a height above the cutting surface that does not initiate the shut-off valve  42 .  
         [0048]     It will be understood that this disclosure, in many respects, is only illustrative. Changes may be made in details, particularly in matters of shape, size, material, and arrangement of parts without exceeding the scope of the invention. Accordingly, the scope of the invention is as defined in the language of the appended claims.