Abstract:
A lift arm controller for a refuse truck has a lift arm, a gripper dimensioned for gripping and holding a refuse container, a carriage on the lift arm to translate along it and a gripper mounted on the carriage. A lift actuator is operationally attached to the carriage to translate the carriage, gripper and the refuse container along the lift arm. At least one sensor is configured to sense when the carriage is entering a near end portion of the lift arm and a signal to a controller. The controller is in operative communication with the sensor and the lift actuator and is configured to signal the lift actuator to operate at a slower speed when a signal is received from the sensor. The sensor may be an inclinometer. The inclinometer may also be used to maintain the gripper in a substantially level orientation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    None. 
       BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    This invention is in the field of refuse collection truck equipment, especially extendable arms and grippers and the control thereof. 
         [0004]    2. Prior Art 
         [0005]    Refuse trucks have long had a variety of extendable apparatuses such as arms for engaging grippers with garbage cans, dumpsters, and the like, in order that they may be lifted and their contents dumped into the hopper of a refuse truck. These apparatuses are typically fairly heavy steel devices commonly driven by hydraulics. There is a constant need in the art for smooth operation of such apparatuses in order that the trash and garbage in containers being dumped be efficiently deposited into the refuse truck without spillage, and that the apparatuses remain durable through many cycles of use. In the state of the art, devices used for control of lift arms, extensions, grippers, and other apparatuses used to reach out, grasp, lift and dump garbage cans and dumpsters have been mechanical or hydraulic in nature, such as springs, or dual-action hydraulic cylinders. 
         [0006]    Refuse trucks also have multiple apparatuses and systems for executing multiple necessary steps in the collection of refuse. For example, after lifting and dumping trash into a hopper, the trash is packed and compressed by a separate compression mechanism. Due to the space limitations and other practical considerations, all of these multiple systems need to be assembled onto a single truck and operate together. In the prior art, where space considerations forced certain apparatuses such as packers and lifters to occupy the same space, the solution has been to simply operate them sequentially, having a consequent loss of time efficiency in many circumstances. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is a control system for a lifting and dumping apparatus for a refuse truck. 
         [0008]    A lift arm controller for a refuse truck has a lift arm, a gripper dimensioned for gripping and holding a refuse container, a carriage disposed on the lift arm to translate along it and a gripper mounted on the carriage. A lift actuator is operationally attached to the carriage to translate the carriage, gripper and the refuse container along the lift arm. The lift actuator has a faster speed and a slower speed. At least one sensor is disposed to sense when the carriage is entering a near end portion of the lift arm and is configured to send a signal to a controller when the carriage is entering a near end portion of the lift arm. The controller is in operative communication with the sensor and the lift actuator and is configured to signal the lift actuator to operate at the slower speed when a signal is received that the carriage has reached the lift arm end portion. The sensor may be an inclinometer. The inclinometer may also be used to maintain the gripper in a substantially level orientation. 
         [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic overview of a refuse truck. 
           [0011]      FIG. 2  is a schematic side view of an extension arm and gripper apparatus for a refuse truck. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Referring now to the figures in which like reference numbers indicate like elements,  FIG. 1  is a schematic top view of a refuse truck  10 . Refuse truck includes a refuse compartment  12 , receiving hopper  14 , and a cab  16 . Refuse is deposited in the hopper  14  by a lift and dump apparatus  18 . Trash is managed on board by a compressor packer apparatus  20 . An operator may control the functions of various systems on the refuse truck from the cab  16  using a central process system, adding a central processor  22  in operative electric communication with the motors, hydraulics and other equipment described below for executing necessary movements for refuse collection. The operating system may also include controls such as, for example, a joy stick  24 , a panel of switches  28 , and a display  26 . 
         [0013]      FIG. 2  is a schematic side view of refuse collection lifting and dumping apparatus  30 . The components of the lifting and dumping apparatus  30  include an extending arm  32  configured to extend in a position to engage a garbage can, a gripper  34  typically comprised of a pair of horizontal pincers whose structure and function are well known to those skilled in the art. The extending arm  32  may be extended by any of a variety of apparatuses for that purpose, which typically include some sort of drive arm  36  engaged with a powered driver, for example, a hydraulic arm indicated schematically at  38 . In this manner, the truck may remain parked on the street, while the extension apparatus  30  extends to engage the gripper  34  with the trash can or dumpster to be dumped. 
         [0014]    Having engaged the trash can in a known manner, the grippers must be elevated to a position where the trash can may be emptied into the hopper  14 . This is typically executed by a lift mechanism  40  which is often comprised of a lift chain  42  driven by a sprocket  44  powered by a driver such as a hydrostatic motor, which is omitted from  FIG. 2  for clarity. The chain  42  extends through any of a variety of known guides and idlers down the extension arm  32  to a position where it is engaged with a carriage  50 . The gripper assembly  34  is mounted on the carriage  50 . This mounting includes a leveler for the grips  34  which may be, for example, a hydraulic arm  52 . Upon receiving a signal, the lift power supplied, for example, by a hydrostatic motor, turns the sprocket  44 , which in turn drives the chain  42  which translates the carriage  50  up and across the extension arm  32  in order to lift the grip assembly  34  and the trash can. 
         [0015]    At the top of the extension arm  32 , the trash is dumped by tilting or inverting the trash can with the grippers  34 . This may be done actively, or, as in the depicted embodiment, by rotating the trash can in order to invert it and empty its contents. This rotation may be actuated with a curved upper portion of the extension arm  60 . By rounding the curve, the carriage  50  will tilt the grippers  34  in order to invert the trash can and empty it into the hopper  14 . Thereafter, upon receipt of a signal, the hydrostatic motor can reverse the drive of the sprocket  44  and chain  42  in order to translate the carriage  50  back down the extension arm  32  to its lower end  62  for positioning the trash can proximate to the ground once again and thereafter signaling the grippers  34  to release it. 
         [0016]    The control system of the present invention deploys a variety of sensors throughout the lifting and dumping apparatus. These sensors include an inclination sensor  70  on the gripper assembly  34  and an inclination sensor  72  on the extension arm  32 . Sensors may also include terminal proximity sensors  74  and  76  at the upper  60  and lower  62  end portions of the extension arm  32 . Proximity sensors may further be deployed along the extension drive apparatus  36  such as depicted at  78  and  80 . Proximity sensors may be further deployed in the drive apparatus  40  such as those depicted at  82  and  84 . The sensors indicated are all in electric signal transmission communication with a central control system, and more particularly a central processor  22 . Some proximity sensors such as those at  78  and  80  may be deployed to indicate when the extension drive apparatus is fully extended and fully retracted. More particularly, these proximity sensors may be deployed near, but not at the end stop of, a fully deployed or fully retracted position. By sensing when a movement of the heavy, hydraulically driven apparatus is near its end, the receipt of the near-the-end signal from the sensor  78  or  80  may be received by the central processor  22  and may be followed by a deceleration signal from the central processor  22  to the drive means  38  for the apparatus&#39; movement has been sensed to be nearly complete. By decelerating the movement of the heavy parts before an end stop, hard impacts that shorten the useful lifespan of the overall apparatus may be advantageously avoided. 
         [0017]    Such damaging impacts are particularly noticeable in chain drive apparatuses. Accordingly, useful lifetime-preserving deceleration signals may be sent in response to near-the-end signals received from proximity sensors such as  74  or  76  disposed at either end of a range of travel of a chain-driven apparatus such as along the extension arm  32 . Additionally, or alternatively, the position of the carriage  50  and its load may be tracked by monitoring the chain itself  42 . Hence, a proximity sensor may be disposed at position  84  to sense the proximity of chain links or link pins in sequence and to activate a counter as they pass. The central processor  22 , having been initialized with a known number of chain links or link pins, may thereby monitor the position of the carriage  50  and load along their vertical translation up and down extension arm  32 . Alternatively, a sensor  82  may be disposed to count the passage of bolts or the components of the sprocket  44  as they pass, also thereby monitoring the position of the load. Another alternative is to engage both the chain links and the sprocket in order to have an advantageous sense of a coarse measurement and a fine measurement of the position of the carriage  50  and load. 
         [0018]    The control system of the present invention also monitors the inclination of the grippers  34  in order to advantageously control them to maintain them and their load in a horizontal position relative to the ground as they are lifted vertically and diagonally while translating along the extension arm  32 . Hence, the inclination sensor  70  signals the central processor  22  with a signal of the inclination of the grippers  34 . Either continuously or in response to passing preconfigured thresholds, the central processor is preconfigured to output signals to the gripper leveler hydraulic cylinder  52  to execute a compensating extension or retracting of its hydraulic arm in order to tilt the grippers in a manner to maintain them in a horizontal position until they reach the top of the extension arm  60 . At the top of the extension arm  60 , the controller receives a signal indicating the arrival of the carriage  50  at the top, and thereafter outputs a signal to the gripper leveler  52  to either stop compensating, or actively retract in order to pull the grippers further over and execute the dump of the garbage can contents. 
         [0019]    Another inclinometer or inclination sensor  72  may be placed on the extension arm itself, or, in the alternative, on the extension driver apparatus  36 . Critical inclinations may be preconfigured in the control processor to change its output signals as described below. Because of the space constraints in refuse trucks, the top portion  60  of the extension arms and some configurations, particularly those that are designed to pivot at their top, cause the top end  60  of the extension arm  32  to project into the hopper, which is disadvantageous for packing processes as the packer may impact the extension arm  32 . The present invention may advantageously output signals that alter the stop point for movement of the carriage  50  and its load upwards and towards the hopper. At higher angles of inclination, where the truck and trash can are originally closer together, the output signal would cause the carriage to travel farther around the curve at the top  60  of the extension arm  32  in order to ensure the trash can&#39;s contents are dumped. However, at greater or more horizontal extension angles, the inclination sensor  72  may indicate those angles to the central processor  22 , which may thereafter output a signal to the drive chain driver to stop at a position short of the very top end of the extension arm  32 . Because the apparatus thus extended is already inclined somewhat, only a marginally decreased amount of further inclination is needed to dump the contents. By achieving the unloading of the can without full travel of the carriage  50 , the packing apparatus may be engaged earlier, since the carriage, load and other components of the extension apparatus  30  are clear of the packer&#39;s operational travel, thus advantageously saving time. 
         [0020]    As various modifications could be made to the exemplary embodiments, as described above with reference to the corresponding illustrations, without departing from the scope of the invention, it is intended that all matter contained in the foregoing description and shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.