Abstract:
A tillage implement spanning a lateral distance relative to a forward direction and having a plurality of carrier frames, each for supporting a plurality of soil engaging tools. A pivoting wheel assembly positions the carrier frames at a variable distance from the soil and an actuator is connected between the carrier frame and each support wheel assembly to vary the height of the carrier frame. The actuator has a sensor for generating a signal reflecting the displacement of the actuator. The sensor element is mounted in an adjustable sensor support and countersunk by the required clearance between the sensor element and encoded information on the output shaft so that the sensor support may be adjusted to abut the shaft and accurately position the sensor element.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a non-provisional application based upon U.S. provisional patent application Ser. No. 61/914,566, entitled “AGRICULTURAL IMPLEMENT ACTUATOR SENSOR PROTECTION”, filed Dec. 11, 2013, which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to agricultural implements, and, more particularly, sensors for use with actuators in such implements. 
         [0004]    2. Description of the Related Art 
         [0005]    In the continuing quest for providing greater efficiency in the operation of farm implements, machines have been constructed to have ever increasing lateral spans relative to a tractor or central unit propelling the unit over a field. When the span increases to realize greater efficiency and speed, the criteria of having a uniform and level tool contact with the soil becomes extremely critical. Equipment with significant lateral spans has many different joints and is usually articulated to enable transport to and between fields. 
         [0006]    An area of special importance to level positioning of farm implements is found in the tillage field. The desirable outcome is a uniform physical depth of the tillage and a uniform entry of the disk blades or harrows into the soil. The need to have a level positioning of the implement is made more challenging with the use of hydraulic actuators which control the depth of penetration of the disk blades or other tools. In current practice, hydraulic actuators are connected in series and it is possible through normal operation for hydraulic fluid leakage to make the actuators out of sync with one another. 
         [0007]    It is current practice to counter this occurrence by fully elevating the implement to the point where bypass lands in the actuators allow full flow of hydraulic fluid to pass through the actuators and again synchronize the multiple units. However, this adds an additional step to the operation, particularly in the field, thereby decreasing the efficiency and speed with which the particular task is accomplished. It has been proposed in co-pending application entitled “Remote Leveling of Tillage Implements”, of common assignment with the present invention, to incorporate position sensors into hydraulic actuators to achieve remote leveling. With such an arrangement, the accuracy of the displacement sensors used in the system is important. Current displacement sensors are employed by fixing them at a minimum clearance from the actuator output shaft to read signals reflecting displacement of the output shaft. In the agricultural environment, the positioning of the sensor is a problem because the current practice of inserting the sensor until contact with the shaft and then backing it off may result in alteration of the sensor signal. 
         [0008]    What is needed in the art therefore, is the accurate and safe installation of a sensor used with an agricultural implement actuator. 
       SUMMARY OF THE INVENTION 
       [0009]    An advantage of the present invention is a more robust and effective sensor used in the synchronization of multiple sections of a farm implement. 
         [0010]    In one form, the invention is an actuator for a tillage machine, the actuator including an actuator housing forming a cylinder and a piston displaceable in that cylinder in response to hydraulic fluid. An output shaft is connected to the piston and extends outside of the actuator housing to provide a variable extension in response to hydraulic fluid inputs. The shaft is encoded with information reflecting the displacement of the output shaft relative to the actuator housing. A sensor is mounted in the housing and has an end face positioned for reading the encoded information. A sensor support surrounds the sensor with the sensor being counter sunk in the sensor support by the amount of clearance necessary between the end face of the sensor and the shaft for sensing of the encoded material. The sensor support is adjustably mounted in the actuator housing to abut the output shaft. 
         [0011]    In another form, the invention is an agricultural implement spanning a lateral distance relative to a forward direction over soil, with the implement including a plurality of carrier frames, each for supporting a plurality of soil engaging tools. At least one supporting element is carried by each carrier frame for variably positioning the carrier frame relative to the soil. An actuator is connected between each supporting element and the respective carrier frame for varying the position of the respective carrier frame relative to the soil, the actuator including a housing forming an internal cylinder and a piston displaceable in the cylinder in response to hydraulic fluid input. An output shaft is connected to the piston and extends outside of the actuator housing to connect between the carrier frame and the supporting element to vary the position of the carrier frame relative to the soil. The output shaft is encoded with information reflecting the displacement of the output shaft relative to the actuator housing. A sensor is mounted in the housing and has an end face for reading the encoded information. A sensor support surrounds the sensor with the sensor being counter sunk in the sensor support by the amount of clearance necessary for sensing of the encoded material on the output shaft with the sensor support being adjustably mounted to abut the output shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0013]      FIG. 1  illustrates a tillage implement including a support of disk blades embodying the present invention, being pulled by a tractor shown in schematic fashion; 
           [0014]      FIG. 2  is a plan view of a hydraulic system shown in the prior art for the tillage implement of  FIG. 1 ; 
           [0015]      FIG. 3  is a plan view of a hydraulic system for the tillage implement of  FIG. 1   
           [0016]      FIG. 4  is a partial detailed view of a prior art actuator used for tillage implements. 
           [0017]      FIG. 5  is a partial detailed view of a preferred actuator used in the tillage implements of  FIGS. 1 and 3 ; and 
           [0018]      FIG. 6  is a partial detailed view of an alternate actuator used in the tillage implements of  FIGS. 1 and 3 . 
       
    
    
       [0019]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiment of the invention and such exemplifications is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a tillage apparatus  10  which generally includes a tractor  12  shown schematically and an agricultural tillage implement  14  for tilling the soil prior to seeding. It should be noted that many different tools may be employed with the tillage implement  14  beyond the embodiment shown. 
         [0021]    Agricultural tillage implement  14  is configured as a multi-section field disk ripper  14 , and includes a carriage frame assembly  16 . Carriage frame assembly  16  is the section that is directly towed by a traction unit, such as agricultural tractor  12 . Carriage frame assembly  16  includes a pull hitch  18  generally extending in a travel direction  20 , and forward and aft oriented carrier frame members  22  which are coupled with and extend from pull hitch  18 . Reinforcing gusset plates  24  may be used to strengthen the connection between pull hitch  18  and carrier frame members  22 . 
         [0022]    The tillage implement  14  has a center section  26 , an inner right wing section  28  and an outer right wing section  32  as viewed in  FIG. 1 . A left inner wing section  30  connects with a left outer wing section  34 . The center section  26  is pivotally connected to the inner wings  28  and  30  by pivotal interconnections at  36 . The right inner wing section  28  and right outer wing section  32  are pivotally interconnected at  38 . The left inner wing section  30  and outer left wing section  34  are interconnected at pivotal joints  40 . The details of the pivotal joints are omitted to enable a clearer understanding of the present invention. However, it should be understood that the pivotal connections allow articulation of the various sections between a field position in which each of the sections are substantially in a common plane and a transport position in which the outer wing sections  32  and  34  are folded, as well as the inner wing sections  28  and  30 , to enable sufficient road clearance. 
         [0023]    Actuator assemblies  42  are connected between the center section  26  and inner wing sections  28  and  30  to enable pivoting between the field and transport position. Actuator assemblies  44  are interconnected between right inner wing section  28  and outer right wing section  32  as well as inner left wing section  30  and outer wing section  34  to enable the pivoting movement. 
         [0024]    The center section  26  has a forward frame member  46  extending across carrier frames  22  and secured thereto. Center section  26  additionally has an aft frame member  48  structurally interconnected with carrier frames  22  at their aft end. As is noted, the frame elements  46  and  48  extend generally laterally with respect to the direction of movement  51  of the agricultural implement. Frame members  46  and  48 , however, extend at an angle as is known in the tillage art to produce appropriate working of the soil. The frame members  46  and  48  provide support beneath them for gangs of disc blades  50 . The gangs of disc blades  50  are resiliently connected to the frame elements in appropriate fashion to provide smooth working of the soil. 
         [0025]    The inner wing sections  28  and  30  each have a forward frame member  52  and an aft frame member  54 . These frame members are interconnected by forward and aft oriented inner frame members  56  and outer frame members  58 . The forward and aft frame members  52  and  54  form an extension of forward and aft frame members  46  and  48 . The forward and aft frame members  52  and  54  each also support gangs of disc blades  50 . 
         [0026]    The outer wing sections  32  and  34  each have forward and aft frame members  60  and  62  which each support gangs of disk blades  50 . Frame members  60  and  62  are interconnected by inner frame members  64  and outer frame members  66 . 
         [0027]    The various sections  26 ,  28 ,  30 ,  32  and  34  of the tillage implement  14  are positioned at variable positions relative to the soil and thus set the position of the gangs of disk harrows  50  above the soil and the depth they cut into the soil. As illustrated, variable support elements for the sections are shown as wheel sets but it should be understood that other forms of variable support may be employed. As illustrated, wheel sets  68  are pivotally interconnected with carrier frames  22  so that they provide support to the forward and aft frame members  46  and  48  relative to the soil. Wheel sets  70  are interconnected with frame element  58  to variably position inner wing sections  28  and  30  relative to the soil. In addition, wheel sets  72  are pivotally mounted on frame members  66  to position outer wing sections  32  and  34  at a variable distance relative to the soil. Actuators  74  and  76  manipulate wheel sets  68  to establish the distance of center section  26  relative to the soil. Actuators  78  and  80  establish the position of sections  28  and  32  relative to the soil. Finally, actuator assemblies  82  and  84  position sections  30  and  34  relative to the soil. 
         [0028]    In addition, castor wheel assemblies  86  on section  32  and  88  on section  34  orient the for and aft angle of the tillage implement  14  relative to the soil. Actuators  90  and  92  are employed for this purpose. 
         [0029]    The actuators described above are shown as hydraulic and for this purpose a hydraulic control unit  94  is mounted in the tractor  12  and has a pump  100  for pressurizing hydraulic fluid to control the actuators. The hydraulic control unit  94  receives inputs from an electronic control unit (ECU)  96  which receives various inputs set out below, in addition to an operator input through control unit  98 . 
         [0030]    The hydraulic interconnection established by a typical prior art system for elevating the various sections of the tillage implement  14  is shown in  FIG. 2 . In this arrangement, each of a set of actuators  102   a,    104   a,    106   a  and  108   a  is connected to a hydraulic control pressure by supply conduits  110   a  and  112   a.  As is illustrated in  FIG. 1  the actuators  102   a - 108   a  are connected in parallel so that the pressure uniformly applies to each actuator in the set. As described above however, the actuators may become out of sync due to linkage past a piston thus requiring additional steps in the field to ensure synchronization of the actuators. 
         [0031]    In accordance with the present invention, a control system and method set forth in  FIG. 3  overcomes these difficulties.  FIG. 3  shows actuators  74 ,  76 ,  78  and  80 . The operation of the additional actuators is similar and is omitted to enable a better understanding of the present invention. Each of the actuators  74 ,  76 ,  78  and  80  has an output shaft  75 ,  77 ,  79  and  81 , respectively. The piston end of the actuator  74  is connected to the hydraulic control unit  94  by a hydraulic line  102 . The output shaft end of actuator  74  is connected to the hydraulic control unit  94  by a return line  104 . In similar fashion, the piston end of actuator  76  is connected by line  106  and a return line  108  is provided to control unit  94 . The piston end of actuator  78  is connected to hydraulic control unit  94  by line  110  and the return line is designated as  112 . Finally, the piston end of actuator  80  is connected to hydraulic control unit  94  via hydraulic line  114  and a return line  116  is provided. The independent connection of the actuators to the hydraulic control unit  94  will enable independent establishment of the height of the units relative to the soil. 
         [0032]    The relative physical position of the hydraulic control unit  94  may be different than the one shown in  FIG. 3  depending up on the application for the unit. It may be a single module or may be provided in individual control sections. However the hydraulic control unit  94  is positioned relative to the actuators, it permits independent manipulation of the actuator output shafts as will be described below. 
         [0033]    For this purpose a displacement detecting device is provided to provide a signal proportional to the displacement of each output shaft relative to the body of the respective actuator. In addition to the displacement signal, a signal reflecting the rate of change of displacement or Δ D/Δ T is provided. The displacement indicating devices are identified as  118  for actuators  74 ,  120  for actuators  76 ,  122  for actuator  78  and  124  for actuator  80 . The displacement indicating devices  118 ,  120 ,  122  and  124  provide signal inputs to the ECU via lines  126 ,  128 ,  130  and  132 , respectively. The displacement indicating devices are devices that provide appropriate control signals that are proportional to the displacement of the output shaft relative to the various actuators and preferably the rate of change of displacement. The interconnections with the two parts will be described below. Any one of a number of sensors may be employed for this purpose. 
         [0034]    As shown, the displacement sensors and Δ D/Δ T sensors are incorporated into a single unit. However, the Δ D/Δ T signal may be provided in a separate unit  119  shown in dashed lines for actuator  74 . Unit  119  may be connected to ECU  96  by a line  127 , also shown as a dashed line. Similar units would be provided for actuators  76 ,  78 , and  80  if it is desired to use separate units for displacement and Δ D/Δ T signals. The invention is applied to the tillage implement of  FIG. 1  by initially setting the implement on a level surface for calibration. Individual readings of the displacement between the actuator rod and the actuator body are taken with full hydraulic fluid in the chambers. The displacement signals of the individual actuators are stored in the ECU  96 . The tillage implement is then in a position to have each of the actuators raise and lower the individual frame elements in unison to provide a uniform height above the ground and a uniform depth when the gangs of disk blades  50  are positioned in the soil. Periodically during the operation of the tillage implement the readings of the individual actuators are determined and if they deviate from the set point initially established the hydraulic control system provides appropriate hydraulic fluid to achieve the same set point. This is done independently of the other actuators so that correction is applied individually to each actuator unit. The tillage implement is then able to provide accurate depth of penetration among the gangs of disk harrows  50 . In addition the actuators are corrected for the differential rate of displacement change by the Δ D/Δ T so that the entry of the gangs of disk blades  50  is uniform at the beginning of the field and the withdrawal is uniform at the end of the field. The process of recalibration may be made automatic so that it does not interfere with the immediate operator directed tillage over a field and preparing the soil. 
         [0035]    Key to the successful functioning of the system above is the accuracy of the displacement sensors  118 ,  120 ,  122  and  124 . These sensors provide a signal output that reflects the actual extension of the actuator output shafts relative to the actuator housing and therefore the level of the carrier frames and gangs of disk blades  50  above the soil.  FIG. 4  shows the installation of a prior art sensor, which will be illustrated in connection with actuator  74 . The cross section view shows the actuator output shaft  75  having information encoded on an exterior surface  140 . This information is placed longitudinally along shaft  75  so as to provide a signal with a sensor  142  that is proportional to the displacement of output shaft  75  relative to actuator housing  74 , in response to hydraulic inputs on a piston  144 , longitudinally displaceable in an interior chamber  146  in the actuator housing. A sensor mounting base  148  is integral with the actuator housing  74  and has an internal bore  150  for receiving the sensor  118 . As illustrated, sensor  118  is cylindrical in form and fits within a corresponding opening  150  in the sensor mounting base  148 . Sensor  118  has a sensor element  152  with an end face that is spaced at a given, relatively close clearance, from the encoded material  140  on shaft  75 . An adjustable mounting  154 , shown as a pair of nuts, allows the sensor  118  to be mounted so that there is the predetermined clearance between end face  152  and encoded material  140  on shaft  75 . 
         [0036]    It is current practice for installing sensor  118  to insert it into bore  150  until the end face of sensor element  152  abuts the encoded information  140  on shaft  75  and then back off the sensor by the degree to which a clearance must be maintained. The sensor  118  has a threaded exterior which corresponds with threads on the interior wall of cylindrical bore  50 . The sensor  118  is then threaded into the bore  150  until end face  152  abuts shaft  75 . The sensor  118  is then backed off by the amount necessary for the clearance which is typically less than 1 mm. Once at that estimated clearance, the lock nuts  154  are tightened to hold it in that position. One of the problems with such an arrangement for the sensor  118  is that the end face  152  may be damaged by abutting the shaft  75  since threading in can provide a significant force urging the sensor element  152  into shaft  75 . This can have an adverse effect on the accuracy of the system. 
         [0037]    In accordance with the present invention, the sensor support described in  FIGS. 5 and 6  is employed to minimize if not eliminate this problem. The reference numbers for the actuator parts will be the same to simplify the description of the invention. In  FIG. 5 , a sensor support  156  is cylindrical in form and threaded into the threaded portion  150  in sensor mounting  148 . The same lock mechanism  154  is positioned at the top. The sensor element  152  is recessed into the end face  158  of sensor support  156  so that the surface of sensor element  152  is a predetermined distance d from the end of end face  158  of sensor support  156 . As stated above, this gap is relatively small and must be accurately maintained. As a result of the recess d, the sensor support  156  may be advanced towards output shaft  75  until it abuts the shaft. When in that position, the lock mechanism  154  may be operated to lock the sensor support  156  and hence the sensor element  152  in place at a predetermined distance from the shaft  75 . Since the sensor support  156  is simply advanced until contact there is not any possibility of the sensor element  152  from being damaged. As a result, it enables an accurate and reliable setting over an extended period. The arrangement in  FIG. 5  shows one such arrangement for the sensor mounting and the arrangement in  FIG. 6  shows but another. 
         [0038]    Referring now to  FIG. 6 , the actuator elements are the same, but the sensor support  160  is configured to have a concave face  162  facing shaft  75 . The sensor element  152  is recessed into the concave end face  162  by a dimension dl which corresponds to the gap between the sensor element  152  and the shaft  75 . The feature of the concave surface  162  follows the outer contour of shaft  75  so that the sensor element  152  may be oriented properly with respect to the encoded information  140 . In the application of  FIG. 6 , the sensor support  160  is not threaded into the bore but simply displaced linearly and oriented so that the concave surface  162  embraces the outer circumference of shaft  75 . In this embodiment also, the sensor element  152  is protected from inadvertent contact to the shaft  75 , thus ensuring that it will give reliable long term readings. 
         [0039]    Preferably, the sensor supports  156  and  160  are formed from material that is wearable relative to the output shaft and especially the encoded information. Plastic material, such as nylon may be used for the sensor support. 
         [0040]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.