Electronic Parallel Lift And Return To Dig On A Backhoe Loader

Abstract

A backhoe loader 10 with a controller 100 that uses angular signals from at least one sensor to calculate a loader tool angle with respect to the vehicle frame 12 or with respect to the earth and to maintain the loader tool angle via controller generated commands to a tool actuator 60 as a function of the angular signals and commands to a boom actuator 50. The controller 100 enables proportional control of the tool angle via a command input device such as an electronic joystick 21. If the electronic joystick 21 is moved to an appropriate detent position, the controller 100 executes a return to dig function. If the bucket 31 is below the return to dig angle at the time the joystick 21 is moved to the detent position, the controller 100 generates commands to move the bucket 36 to the return to dig angle via a curling motion. If the bucket 31 is above the return to dig angle at the time the joystick 21 is moved to the detent position, the controller 100 generates commands to move the bucket 36 to the return to dig angle via a dumping motion. If either return to dig or a return to carry function while the other is being executed then the two are combined such that return to dig is completed prior to return to carry.

1 . A backhoe loader, comprising:
 a frame;   a boom having a first boom end and a second boom end, the first boom end pivotally attached to the frame;   a tool pivotally attached to the second boom end, the tool being adapted to perform a work function;   a tool actuator adapted to controllably pivot the tool about the second boom end;   a boom actuator adapted to controllably pivot the boom about the frame;   a controller in communication with at least one of the tool actuator and the boom actuator, the controller having a first mode and a second mode;   an command input device in communication with the controller, the command input device having a detent position and adapted to generate a first boom command signal upon a first manipulation of the command input device corresponding to a desired boom movement, the command input device adapted to generate a first tool command signal upon a second manipulation of the command input device corresponding to a desired movement of at least one of the tool and the boom, the joystick adapted to generate a second boom command signal upon a movement of the joystick to a detent position; and   at least one sensor detecting an inclination of the tool with respect to the frame and generating a corresponding tool angle signal indicative of the inclination of the tool, the first mode enabling the controller to receive the first tool command signal and ignore the tool angle signal while generating first controller command signals controlling at least one of the tool actuator and the boom actuator, the second mode enabling controller to respond to the tool angle signal and generate second controller command signals to maintain the inclination of the tool by controlling the at least one of the tool actuator and the boom actuator, the first and second modes enabling the controller to, upon a movement of the joystick to the detent position, execute a return to carry function to drive the boom to a predetermined return to carry boom angle, via controller command signals to the boom actuator, when a current boom angle is higher than the predetermined return to carry boom angle, the movement of the joystick to the detent position enabling the controller to execute a float function, via controller command signals to the boom actuator when the current boom angle is at least one of equal to and lower than the predetermined return to carry boom angle.   
   
   
       2 . The backhoe loader of  claim 1 , further comprising a mode switch, the mode switch having a first state and a second state, the first state placing the controller in the first mode, the second state placing the controller in the second mode. 
   
   
       3 . The backhoe loader of  claim 1 , wherein the command input device is an electronic joystick. 
   
   
       4 . The backhoe loader of  claim 1 , wherein the first manipulation is a fore and aft movement of the electronic joystick and the second manipulation is a fore-aft manipulation of the electronic joystick. 
   
   
       5 . The backhoe loader of  claim 1 , wherein the tool actuator comprises a hydraulic circuit, a hydraulic cylinder and a linkage, the linkage operatively coupled to the hydraulic cylinder and the tool, the linkage and the hydraulic cylinder manipulating the tool as the hydraulic cylinder extends and retracts. 
   
   
       6 . The backhoe loader of  claim 1 , wherein the controller lowers the controller command signals to the boom actuator by multiplying them by X 0.75  when a current boom angle is higher than the first predetermined boom angle and at least one of equal to the first predetermined boom angle plus 10° and less than the first predetermined boom angle plus 10°, X being the angular distance in radians to the first predetermined boom position from the current boom position. 
   
   
       7 . The backhoe loader of  claim 1 , wherein returning the joystick to a neutral position subsequent to the movement of the joystick to the detent position resumes the return to carry command signal enabling the controller to drive the boom to the predetermined return to carry boom angle, via controller command signals, and to stop the controller command signals when the boom reaches the first predetermined boom angle. 
   
   
       8 . The backhoe loader of  claim 1 , wherein, a movement of the joystick to any position between the first detent position and the neutral position prior to the boom reaching the first predetermined boom angle cancels the return to carry command signals and returns the boom to manual control via the joystick. 
   
   
       9 . A loader control system for a backhoe loader, the backhoe loader having a frame, the tool control system comprising:
 a boom having a first boom end and a second boom end, the first boom end pivotally attached to the frame at a first pivot;   a tool pivotally attached to the second boom end at a second pivot, the tool being adapted to perform a work function;   a tool actuator adapted to controllably pivot the tool about the second pivot;   a boom actuator adapted to controllably pivot the boom about the first pivot;   a controller in communication with the tool actuator and the boom actuator;   a command input device in communication with the controller, the command input device adapted to generate a first boom command signal upon a first manipulation of the command input device corresponding to a desired angular boom movement with respect to the frame;   a boom angle sensor proximate to the first pivot detecting the inclination of the boom with respect to the frame and generating a corresponding boom angle signal indicative of the inclination of the boom, the controller capable of receiving the first boom command signal and generating first controller command signals controlling the boom actuator, the controller, upon a movement of the joystick to the detent position, capable of executing a return to carry function to drive the boom to a predetermined return to carry boom angle when a current boom angle is higher than the predetermined return to carry boom angle, the controller, upon the movement of the joystick to the detent position, capable of executing a float function, allowing the tool and the boom to rest on the ground, when the current boom angle is lower than the predetermined boom angle.   
   
   
       10 . The loader control system of  claim 9 , wherein the command input device is an electronic joystick. 
   
   
       11 . The loader control system of  claim 9 , wherein the first manipulation is a fore and aft movement of the electronic joystick and the second manipulation is a fore-aft manipulation of the electronic joystick. 
   
   
       12 . The loader control system of  claim 9 , wherein the tool actuator comprises a hydraulic circuit, a hydraulic cylinder and a linkage, the linkage operatively coupled to the hydraulic cylinder and the tool, the linkage and the hydraulic cylinder manipulating the tool as the hydraulic cylinder extends and retracts. 
   
   
       13 . The loader control system of  claim 9 , wherein the controller lowers the controller command signals to the boom actuator by a function of X where X is the distance between a current boom angle and the first predetermined boom angle when a current boom angle is higher than the first predetermined boom angle and at least one of equal to the first predetermined boom angle plus a cushion start angle and less than the first predetermined boom angle plus the cushion start angle. 
   
   
       14 . The loader control system of  claim 9 , wherein returning the joystick to a neutral position subsequent to the movement of the joystick to the detent position resumes the return to carry command signal enabling the controller to drive the boom to the predetermined return to carry boom angle, via controller command signals, and to stop the controller command signals when the boom reaches the first predetermined boom angle. 
   
   
       15 . The loader control system of  claim 9 , wherein, a movement of the joystick to any position between the first detent position and the neutral position prior to the boom reaching the first predetermined boom angle cancels the return to carry command signals and returns the boom to manual control via the joystick.