Patent Publication Number: US-6336068-B1

Title: Control system for wheel tractor scrapers

Description:
TECHNICAL FIELD 
     This invention relates generally to a control system and, more particularly, to a control system to automate operations for wheel tractor scrapers. 
     BACKGROUND ART 
     Earth moving machinery and more particularly wheel tractor scrapers are complex machines which include a great deal of skill to operate in an efficient manner. This is mainly due to the many complex features that are provided with these machines. 
     By way of example, wheel tractor scrapers include a load carrying bowl which is used to payload material scraped from a ground surface. The load carrying bowl may be moved into many different positions by the use of hydraulic lifts. In addition, the wheel tractor scraper may include several loading gears, aprons and implements (such as, for example, elevators and augers) as well as moveable ejectors and scrapers. All of these features must be controlled by the operator within the tractor cab of the wheel tractor scraper. 
     In order to control these features, the operator must not only be well acquainted with the controls of the tractor cab, but must also be trained to use such controls in the most efficient and safest manner. That is, the operator must be trained to use the controls so that the features of the wheel tractor scraper work in a precise sequence and within design parameters. This ensures that the wheel tractor scraper is working in its intended manner. This training can be quite complex and time consuming. 
     For example, in order to properly use the wheel tractor scraper, the operator must be able to control the raising and lowering of the load carrying bowl, and more particularly must be able to accurately adjust the load carrying bowl in order to ensure that the cutting edge of the load carrying bowl is properly scraping the ground surface. In addition, the operator must know when and how to properly adjust the implements so that the loaded material is properly distributed within the load carrying bowl. Simultaneously, the operator must select a proper loading gear and implement appropriate speeds, as well as select many other variables. To make the operation even more complex, the operator must also drive the tractor which includes steering, transmission shifting, braking and the like during the operation of these other features. 
     In U.S. Pat. No. 3,762,076 to Eftefield issued on Oct. 2, 1973, a hoeing control scraper system is provided. In Eftefield, an electro-hydraulic circuit provides semi-automatic control of movements of the hoeing apron loading device. Several fluid motors provide apron movement and are actuated and stopped by electric signals originating in the control circuit. In this manner, the apron can be efficiently controlled by the Eftefield system, but the Eftefield system still requires the operator to manually control the many features of the wheel tractor scraper. 
     The present invention is directed to overcoming one or more of the problems as set forth above. 
     DISCLOSURE OF THE INVENTION 
     In one aspect of the present invention a control system has a load control module, a haul control module associated with the load control module and an eject control module. The eject control module is associated with the load control module and the haul control module. 
     In another aspect of the invention a method for controlling operations of a wheel tractor scraper is provided. The method has the steps of providing initial preset values for operating the wheel tractor scraper. The method also has the steps of controlling a loading operation, a hauling operation and an ejecting operation using the initial preset values. 
     In still another aspect of the invention a wheel tractor scraper has a tractor mounted to a load carrying bowl. A hitch, cutting edge, moveable ejector, apron and material moving implement are also provided. A load control module, a haul control module and an eject control module control the wheel tractor scraper during a loading, hauling and ejecting operation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a diagrammatic side plan view of a wheel tractor scraper adapted for use with the control system of the present invention; 
     FIG. 2 shows a block diagram of the control system of the present invention; and 
     FIG. 3 shows a flow diagram implementing the control system of the present invention. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     FIG. 1 is a diagrammatic side plan view of a wheel tractor scraper which is used with the control system of the present invention. It should be recognized by those of skill in the art that other wheel tractor scrapers known in the art may also be used with the control system of the present invention, and that the wheel tractor scraper of FIG. 1 is not to be construed to limit in any manner the present invention. 
     The wheel tractor scraper of FIG. 1 is generally depicted as reference numeral  10  and includes a load carrying bowl  12 . A tractor  14  is connected to the load carrying bowl  12  by a hydraulic or non-hydraulic hitch  16 . The tractor  14  is any conventional tractor that is capable of hauling the wheel tractor scraper  10 , and a discussion of such tractor will not be described herein. 
     The load carrying bowl  12  includes a floor  18  having a cutting edge  20 . A rear wall of the load carrying bowl  12  is formed as a moveable ejector  22 . A first set of hydraulic lifts  24  are mounted to a front of the load carrying bowl  12  and a second set of hydraulic lifts  26  are mounted between the moveable ejector  22  and the load carrying bowl  12 . The second set of hydraulic lifts  26  may alternatively be mounted between the moveable ejector  22  and another stationary or fixed location such as, for example, rear wheels  28  of the load carrying bowl  12 . 
     An apron  30  is mounted to the load carrying bowl  12  via an articulated support assembly  32 . The articulated support assembly  32  is moveable between several positions including an opened and closed position by use of a third set of hydraulic lifts  34  mounted to the load carrying bowl  12 . Material moving implements  36  such as an elevator or auger may also be positioned within the load carrying bowl  12  proximate to the cutting edge  20 . Several sensors  38  are provided throughout the wheel tractor scraper  10  and are preferably mounted adjacent to (i) the load carrying bowl  12 , (ii) the hitch  16 , (iii) the cutting edge  20 , (iv) the moveable ejector  22 , (v) the apron  30  and (vi) the material moving implement  36 . 
     Referring now to FIG. 2, a block diagram of the control system of the present invention is provided. The control system is preferably adaptable for use in all currently known wheel tractor scraper configurations and may be either presented in a modular design or a single discrete component. 
     Referring now to FIG. 2, the control system is generally depicted as a controller  40  which includes a load control module  42 , a haul control module  44 , an eject control module  46  and a return control module  48 . The control system  40  also includes an operator display and control system  50  which is associated with the control modules  42 ,  44 ,  46  and  48 . The control modules  42 ,  44 ,  46  and  48  control a loading operation, hauling operation, ejecting operation and return operation, respectively, of the wheel tractor scraper  10 . 
     The operator display and control system  50  of FIG. 2 displays the above operations and may include a calibration system  52  and a self diagnostic function  54 . The operator display and control system  50  also includes controls for presetting the positional values of the material moving implements as well as the other variables. By way of example, the controls of the operator display and control system  50  may include a manual mode control or alternatively include controls for: 
     The hydraulic hitch 
     The apron 
     The load carrying bowl 
     The moveable ejector and material moving implements 
     The load gears 
     FIG. 3 shows a flow diagram implementing the control system of the present invention. In step  54 , the control system of the present invention is activated. In step  56 , the control system prompts the operator to enter new inputs into the control system of the present invention, or alternatively the control system of the present invention may default to previous inputs. The new inputs may be values relating to the load carrying bowl  12 , the hydraulic hitch  16 , the moveable ejector  22 , the apron  30 , the material moving implements  36  and the desired load gear. 
     In step  58 , the control system of the present invention defaults to a loading operation mode. In step  60 , a determination is made as to whether the wheel tractor scraper  10  is positioned at the loading site. If not, the control returns to step  58 . If yes, the control system initiates and begins the loading operation mode in step  62 . 
     In step  64 , a determination is made as to whether the loading operation is completed. If not, the control system of the present invention remains in a loading operation mode in step  66 , and then returns to step  64 . If the loading operation is completed, the control system defaults to the haul mode in step  68 . 
     In step  70 , a determination is made as to whether the wheel tractor scraper  10  is in the eject area. If not, the control remains in the haul mode in step  68 . If a positive determination is made in step  70 , the control system will activate the hydraulic lifts  22  in order to eject the material from the load carrying bowl in step  72 . 
     In step  74 , a determination is made as to whether the ejecting operation is completed. If not, the control system returns to step  72 ; however, if the ejecting operation is completed then the control system ends in step  76 . It is noted that each operational step including the steps of  62 ,  68  and  72  may be displayed on the display and control system  50 . 
     Industrial Applicability 
     In use, the wheel tractor scraper  10  is controlled by the controller  40  in four modes of operation, a loading operation, a hauling operation, an ejecting operation and a return operation. The controller  40  automates these four modes of operation, via the control modules  42 ,  44 ,  46  and  48 , by controlling the hydraulic hitch  16  and the hydraulic lifts  24 ,  26  and  34 , as well as monitoring these systems via the sensors  38 . The sensors  38  provide positional values for the many features of the wheel tractor scraper such as, for example, the load carrying bowl  12 . This allows the control system of the present invention to automatically execute the many operational modes of the wheel tractor scraper  10 . The operations may be initially activated by an operator by, for example, a toggle switch, push button or other activating mechanism. 
     Prior to the loading operation, the control system of the present invention prompts the operator to provide initial preset values in the display and control system  50 . These preset values may include (i) whether the hydraulic hitch  16  is to be locked or unlocked during the ejecting and returning operations, (ii) the apron  30  position for the ejecting operations, (iii) the load carrying bowl  12  position for the loading, hauling and ejecting operations, (iv) the moveable ejector  22  speed, (v) the material moving implement speed and (vi) the desired load gear. Prior values may also be used with the control system of the present invention. 
     In the case of entering the values of (ii) and (iii), the operator may manually position the material moving implement and thereafter activate a set button on the display and control system  50 . In the preferred embodiment, prior to setting the initial conditions, the operator will set the load carrying bowl  12  on the ground in order to calibrate the load carry bowl  12  to “0” depth (via the calibration button  52 ). 
     In the loading operation, the hydraulic hitch  16  is locked in a down or stationary position and the transmission of the wheel tractor scraper  10  is locked into a loading gear. The loading gear is preferably a first, second or third gear of an eight gear system. The moveable ejector  22  is checked to ensure that it is properly positioned in a back position, and the apron  30  is set within preset parameters (i.e., operator input open position) by activating the hydraulic lifts  34 . The material moving implements  36  are also activated, at a preset operator parameter (as set in step  56  of FIG.  3 ). 
     In the loading operation, the hydraulic lifts  24  are also activated by the control system so that the load carrying bowl  12  can be lowered and the cutting edge  20  can begin to scrape the ground surface. As the cutting edge  20  scrapes the ground surface, material is loaded into the load carrying bowl  12 . The material moving implements  36  may push the material within the load carry bowl  12 . 
     Once the loading is completed, the control system is toggled into the hauling operation. In the hauling operation, the material moving implements  36  are deactivated and the apron is closed over the load carrying bowl  12  (via the articulated support assembly and hydraulic lifts  34 ). In this operational mode, the load carrying bowl  12  is also raised to a carry position. The hydraulic hitch  16  may be activated or unlocked (i.e., set to absorb road shock and stabilize machine travel) and the transmission of the wheel tractor scraper  10  is unlocked from the loading gear. The operator then transports the loaded material to an ejecting site. 
     Thereafter, the control system is toggled into the ejecting operation and the hydraulic hitch  16  is locked in the down or stationary position. The load carrying bowl  12  is raised by the hydraulic lifts  24 . The apron  30  is also opened while the material moving implements  36  are activated. During this operational mode, the load within the wheel tractor scraper  10  is ejected from the load carrying bowl  12  at an operator selected rate (selected in step  56  of FIG. 3) for the moveable ejector  22 . 
     The control system then automatically toggles into the return operation. At this operational stage, the control system automatically deactivates the material moving implements  36  and the load carrying bowl  12  is raised to a preset position (set in step  56 ). In this operational mode, the apron  30  is closed and the hydraulic hitch  16  may again be unlocked so as to absorb road shock and stabilize machine travel. The moveable ejector  22  is returned to an initial back position. 
     The operator display and control system  50  displays these operations. Also, during these operations, the self diagnostic function  54  is capable of continuously monitoring all operations of the wheel tractor scraper  10 , and may display an error message when an operation is not working properly. 
     Other aspects and features of the present invention can be obtained from a study of the drawings, the disclosure, and the appended claims.