Abstract:
A hydraulic control for an attachment on a work vehicle. Power is provided to the attachment by manually actuating a control lever that is biased toward a first position. This first position corresponds to a deactuated mode of the attachment. By unlocking a lock mechanism, the lever may be maintained in a second position under hand pressure. This second position corresponds to an actuated mode of the attachment. The lock mechanism may be actuated by an operator platform-actuated release mechanism. While an operator is on a platform on the vehicle, the loch mechanism remains unlocked, and the lever may be maintained, without hand pressure, in its second position. The release mechanism actuates the lock mechanism when an operator is not on the platform. As a result, the bias of the control lever returns it to its first position, and the attachment is deactuated. A filter may be utilized to prevent premature actuation of the release mechanism.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/249,561 filed on Nov. 2, 2015, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    This invention relates generally to a system for controlling continuous operation of an attachment. 
       SUMMARY 
       [0003]    The invention is directed to an apparatus. The apparatus comprises a lever, a lock, a release mechanism and a platform. The lever is movable from a first position to a second position. The lock is configured to hold the lever in the first position. The release mechanism is configured to release the lock. The platform is movable from a first position to a second position. The platform contacts the release mechanism in the first position and does not contact the release mechanism in the second position. The release mechanism releases the lock when the platform is in the first position. 
         [0004]    In another embodiment, the invention is directed to a work machine. The work machine comprises a chassis, a work attachment disposed on a first end of the chassis, a platform, a hydraulic power source, a valve, a lever, a lock, and a release mechanism. The platform is disposed on a second end of the chassis and movable from a second position to a first position. The valve is operable in a first mode where hydraulic power from the hydraulic power source is provided to the work attachment and in a second mode where hydraulic power is not provided to the work attachment. The lever toggles the valve from the first mode to the second mode and is biased to maintain the valve in the second mode. The lock holds the lever such that the valve is in the first mode. The release mechanism releases the lock when the platform is in the first position. 
         [0005]    In another embodiment, the invention is directed to a method. The method comprises placing a weight on a platform to move the platform from a first position to a second position, actuating a control to provide power to a work attachment, locking the control in a position where power is provided to the work attachment, and removing the weight from the platform. The control is biased to a position where power is not provided to the work attachment. Removing the weight causes the platform to move to the first position and actuate a release mechanism to unlock the control and cut off power to the work attachment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a side view of a trencher having an operator platform. 
           [0007]      FIG. 2  is a back left perspective view of an operator station for a work machine. 
           [0008]      FIG. 3  is a back left perspective view of the operator station of  FIG. 2 . 
           [0009]      FIG. 4  is a side view of a release mechanism for use with a work machine. 
           [0010]      FIG. 5  is a side view of a platform for use with a work machine. 
           [0011]      FIG. 6  is a top view of a control panel for use with the work machine of  FIG. 2 . 
           [0012]      FIG. 7  is a schematic of a hydraulic control for a work machine wherein a low-flow operating condition is chosen and an attachment in an operating condition. 
           [0013]      FIG. 8  is the schematic of  FIG. 7  with a medium-flow operating condition chosen and the attachment in a neutral condition. 
           [0014]      FIG. 9  is the schematic of  FIG. 7  with a high-flow operating condition chosen and the attachment in a neutral condition. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    With reference to  FIG. 1 , a work vehicle  10  with an operator platform  12  is shown. An operator  14  is shown standing on the operator platform  12  at a control panel  16 . The operator platform  12  generally extends from the work vehicle  10  a length of twelve to thirty-six inches, and is approximately the width of the work vehicle  10 . The platform  12  may have tread or friction increasing-material on an upper surface to prevent slippage by the operator  14 . 
         [0016]    The work vehicle  10  comprises a chassis  18  and an attachment  20 . As shown, the operator platform  12  is on an opposite end of the chassis  18  from the attachment  20 . The attachment  20  shown is a trencher  22 . Other attachments, such as vibratory plows, buckets, microtrenching assemblies, grapple arms, excavator arms, stump grinders, and the like may be utilized with the chassis  18 . 
         [0017]    When the attachment  20  such as trencher  22  is active, it rotates about the trencher boom  24  to uncover a trench. The operator  14  should stay away from the trencher  22  to avoid serious injury. The same is true for other attachments  20 , which may rotate or impart loads during a construction operation that would be hazardous to an operator  14 . 
         [0018]    With reference now to  FIGS. 2-6 , a system for detecting operator  14  presence on the operator platform  12  is shown. The system comprises a release mechanism  32 , the control panel  16  and the operator platform  12 . As shown in detail on  FIG. 6 , the control panel  16  comprises an attachment operation lever  40 , a lock switch  42  and a hydraulic flow lever  100 . Other controls  44  and displays  46  may be used to perform and observe functions of the work vehicle  10 , such as operation of lift arms, tracks, etc. As shown, the operation lever  40  and hydraulic flow lever  100  are joysticks, though other controls may be utilized. 
         [0019]    The operation lever  40 , when actuated under hand pressure, causes the attachment  20  to operate. The lever  40  has a first actuation position, generally when the lever is move forward, and a second neutral position. When in the neutral position, the attachment  20  does not operate. Attachment  20  operation may be rotation of the trencher  22  chain, vibration of a plow, rotation of a stump grinder, or other primary function of the attachment  20 . The operation lever  40  may be bidirectional, such that the lever  40  may cause forward and reverse operation of the attachment  20 . Alternatively, the operation lever  40  may be actuated in a single direction only. In either case, it is preferable for the operation lever  40  to bias back to neutral when not actuated under hand pressure by the operator  14 . 
         [0020]    The lock switch  42  has a first position and a second position. In the first position, the operation lever  40  returns to neutral position when not actively held by the operator  14 . When the lock switch  42  is in the second position, the operation lever  40  remains in an actuated position until returned to a neutral position. Thus, the attachment  20  continues to operate even when the operator is not actively holding the operation lever  40 . 
         [0021]    One or more detent mechanisms may be used to hold the operation lever  40  in the actuated position. Exemplar detent mechanisms include retractable pins, latches, grippers, magnets, and the like. The detent mechanism may engage the operation lever  40  at any point along its length to hold it into place, may engage a connection feature (not shown) or otherwise restrict the return of the lever to neutral. 
         [0022]    When the lock switch  42  is in the second position and the detent mechanism is holding the operation lever  40 , the operator  14  is free to operate other features of the work machine  10  with the knowledge that the attachment  20  will continue in a “cruise control” mode. 
         [0023]    The release mechanism  32  comprises a detection switch  50  and a filter  52 , as shown with more detail in  FIG. 3 . With reference to  FIGS. 4 and 5 , the platform  12  is attached to the chassis  18  at a pivot  60  and is biased in a first position by a spring  62 . The pivot  60  may comprise two bolts disposed at separate side walls  68  of the platform. 
         [0024]    The spring  62  is preferably made of rubber. The spring  62  extends between the platform  12  and the chassis  18 . The spring  62  may be fixed to the platform  12 . As a distal end of the platform  12  will tend to rotate down relative to pivot  60 , placement of the spring  62  below the pivot  60  will provide the spring to contact the chassis. Alternatively, the spring  62  may be fixed to the chassis  18  in a similar position. 
         [0025]    The spring  62  deforms when the weight of the operator  14  is applied to the platform  12 . As shown, the spring  62  compresses. This compression allows the platform  12  to move from a first position to a second position. Without the application of the operator  14  weight, the spring  62  will bias the platform  12  to the first position. 
         [0026]    Side walls  68  are formed on each side of the platform  12 . The side walls  68  further comprise a tab  66  or other contact structure. The tab  66  is shown integrally formed with the platform  12  on a side wall  68 . Thus, the tab  66 , side wall  68  and platform  12  each rotate about pivot  60 , as restricted by compression of the spring  62 . 
         [0027]    When the platform  12  is in the first position, the platform&#39;s rotation about pivot  60  causes the tab  66  to contact the detection switch  50  of the release mechanism  32 . Thus, the tab  66  indicates the presence of an operator  14  on the platform  12 . When an operator  14  is on the platform  12  and the platform is in the second position, the tab  66  is rotated down and away from the detection switch  50 . 
         [0028]    While a tab  66  is disclosed herein, contact with the detection switch  50  may be made by an edge of the side wall  68 . Additionally, the tab  66  may be configured such that it contacts the detection switch  50  of the release mechanism  32  when the platform is in the second position. In this mode, the tab  66  indicates the presence, rather than the absence, of the operator  14  on the platform  12 . 
         [0029]    The detection switch  50  may be a mechanical plunger or switch, or may detect the proximity of the tab  66  using electrical impedance or optical methods. The release mechanism  32  generates a signal when the tab  66  actuates the detection switch  50 . Preferably, the release mechanism  32  generates a signal when the platform  12  is in the first position, indicating the operator  14  is not on the platform. 
         [0030]    When the detection switch  50  is actuated by the tab, the filter  52  begins to run for a predetermined time. The filter  52  restricts transmission of the signal until it has persisted for a predetermined time. In this way, the filter  52  prevents false signals from reaching the control panel  16 . Once the predetermined time has been reached, the signal is allowed to be sent from the release mechanism  32  to the control panel  16 . If the detection switch  50  indicates that the operator is back on the platform prior to expiration of the predetermined time, the signal is filtered by the filter  52  and is not sent by the release mechanism  32 . 
         [0031]    The signal may be an electrical current, movement of a mechanical structure, a wireless signal, or other mechanism. Further, the signal may comprise the absence, rather than the presence, of the above potential signals. For example, a current may be continuously generated from the release mechanism  32  and received at the control panel  16 . In this scenario, expiration of the predetermined time with the tab  66  actuating the detection switch  50  interrupts the current. The interruption of the current is the signal received by the control panel  16  indicating that the platform is in the first position and thus, the operator  14  is not at the platform. 
         [0032]    Filtering of false signals by the filter  52  is advantageous due to conditions which may cause the platform  12  to move to the first position with the operator  14  on the platform. Such false signals interrupt operation of the attachment  20 . One such condition is a “bump” on the surface of the ground that causes the platform  12  to vertically oscillate. Preferably, the predetermined time is between one and four seconds. More preferably, the predetermined time is two seconds. 
         [0033]    Transmission of the signal by the release mechanism  32  overrides the lock switch  42  and allows the operation lever  40  to return to neutral. This may occur by releasing the detent mechanism. Thus, the operation lever  40  may be placed in a detent condition when an operator  14  is on a platform  12 . However, when the operator  14  leaves the platform  12  for the predetermined time, the operation lever  40  is released and return to neutral. With the operation lever  40  in neutral, the attachment  20  no longer operates. 
         [0034]    With reference now to  FIGS. 7-9 , a hydraulic flow scheme is shown. The work machine  10  comprises a high flow pump  102  and a low flow pump  104 . Hydraulic fluid from high flow pump  102  enters high flow line  103 . Hydraulic fluid from low flow pump  104  enters low flow line  105 . The hydraulic flow lever  100  may be moved to actuate a three-way valve  106  to any selected one of low, medium, and high flow conditions. 
         [0035]    In  FIG. 7 , the valve  106  is in “low flow” condition shown by section  108 . When lines  103 ,  105  are aligned with section  108 , the valve  106  is in a low flow state. In the low flow state, the valve allows delivery of fluid from the low power pump to the attachment  20 , while the high power pump fluid is returned to a fluid reservoir  110 . 
         [0036]    In  FIG. 8 , section  112  is aligned with lines  103 ,  105 . In this condition, the valve  106  is in a “medium-flow” state. The valve  106  allows delivery of fluid from the high power pump  102 , but not the low power pump  104 , to the attachment  20 . 
         [0037]    In  FIG. 9 , lines  103 ,  105  are aligned with section  114 . In this condition, the valve  106  is in a “high-flow” condition. The valve  106  allows delivery of fluid from both pumps  102 ,  104  to the attachment  20 . 
         [0038]    The work machine  10  also comprises a cut-off valve  120  controlled by the operation lever  40 . The cut-off valve  120  comprises a first section  121  and a second section  122 . As shown in  FIG. 7 , flow lines are aligned with first section  121 . In this condition, whichever flow is chosen by three-way valve  106  is aligned with the attachment, and flow is allowed to power operation of the attachment  20 . Thus, the condition of cut-off valve  120  in  FIG. 7  is indicative of actuation of the control lever  40 . 
         [0039]    As shown in  FIGS. 8 and 9 , when the operation lever  40  is in neutral, the cut-off valve  120  aligns flow lines with second section  122 . In this condition, the hydraulic fluid is directed to the fluid reservoir  110  and not to the attachment  20 . Thus, irrespective of the condition of the three-way valve  106 , the cut-off valve  120  may cause the attachment become depowered. This may occur when the operator  18  is not holding the operation lever  40 , or, for example, when the signal has been sent, releasing the detent of the operation lever. 
         [0040]    The work machine  10  disclosed herein provides an operator presence control for operation of an attachment  20 . In operation, an operator  14  stands on the platform  12  and operates the work machine  10  using the control panel  16 . When operation of the attachment  20  is desired, the operator  14  moves the operation lever  40  under hand pressure into an actuated position. When operation is not desired, the operator  14  releases the lever  40 , which biases to a neutral position. 
         [0041]    With the operation lever  40  actuated, the operator may elect to restrict the return of the lever  40  to neutral, allowing actuation of the lever without hand pressure. By actuating a lock switch  42 , a detent mechanism engages the operation lever. With the lever  40  restricted, the operator  14  may operate other controls  44  of the work machine  10  with power to the attachment  20  maintained without actively holding the lever  40  in place. 
         [0042]    Such a mode of operation may be desired when the operator  14  is on the platform  12 , away from moving parts of the attachment  20 . However, when the operator  14  leaves the platform, operation of the attachment  20  may pose a hazard. Thus, the platform  12  is moved from a second position to a first position by extension of the spring  62  when the weight of the operator  14  is removed from the platform. This moves a tab  66  to actuate the detection switch  50 . A filter  52  detects whether a predetermined time has elapsed after actuation of the detection switch. 
         [0043]    If the predetermined time elapses, a signal is sent by the release mechanism  32  to release the detent mechanism. This allows the operation lever  40  to return to neutral and operation of the attachment  20  to cease. If the predetermined time does not elapse before the actuation of the detection switch  50  ceases, the filter  52  prevents the release mechanism from sending the signal, and the lever  40  remains in detent. 
         [0044]    One of ordinary skill in the art will appreciate that modifications may be made to the invention described herein without departing from the spirit of the present invention. For example, hydraulic control schemes are discussed herein. An electric motor may alternatively be used to provide power directly to the attachment when the operation lever is in the first position. In such a configuration, the cut-off valve  120  may be replaced with an electric bypass to shut off current to the attachment  20 . Such an electric bypass may be actuated using the same system disclosed herein for use with hydraulic control.