Abstract:
A device having a winch spool, a torque sensor that measures torque of the winch spool, a first angle sensor that detects a first angle of a winch line relative to a central axis of the winch spool, and a second angle sensor that detects a second angle of the winch line coming from a coil of line on the spool relative to a surface of the coil of line is disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of U.S. Provisional Patent Application No. 61/411,313 entitled “SYSTEM AND METHOD FOR CALCULATING WINCH LINE PULL,” filed Nov. 8, 2010, the contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     This disclosure is directed to winch systems or similar devices in general and, more particularly, to a system for measuring line pull on a winch or similar device. 
     BACKGROUND OF THE INVENTION 
     It is often helpful to know how much a winch or similar device is lifting or pulling. To find this, theoretically, the torque applied by the winch is divided by the distance between the center axis of the winch or similar device and the location where the rope exits the winch or similar device. The equation for this is F=T/X, where F is the weight of the load (or line pull), T the output torque and X is the distance from the center axis of the winch or similar device perpendicular to the point where the rope exits the winch or similar device. In actuality, this calculation is more complicated. The rope rarely winds perfectly onto the drum. Much of the time the line is allowed to wind onto the drum or similar device in a random fashion, creating peaks and valleys for the line to rise and fall into as it changes layers. This means that the X mentioned above is constantly changing. 
     SUMMARY OF THE INVENTION 
     The invention of the present disclosure, in one aspect thereof, comprises a device having a winch spool, a torque sensor that measures torque of the winch spool, a first angle sensor that detects a first angle of a winch line relative to a central axis of the winch spool, and a second angle sensor that detects a second angle of the winch line coming from a coil of line on the spool relative to a surface of the coil of line 
     In some embodiments means for determining a distance from the surface of the coil of line to the central axis of the winch spool utilizing the measured first and second angles is provided. Means for determining an amount of force applied to the winch line based upon torque detected by the sensor and the measured first and second angles may also be provided. This means may determine a distance from the central axis of the winch spool to a point where the winch line leaves the coil based upon the measured first and second angles, and divides the torque by the distance to calculate the force. Such means for determining can comprise a solid state computer. A data bus may provide the measured first and second angle, and torque, to the solid state computer. 
     Some embodiments will provide a bracket for affixing the first and second angle sensors in relation to the winch spool such that the first sensor detects the first angle and the second sensor detects the second angle. The bracket may comprise a swing arm hinged on a first end to a point in a stable relationship with respect to the winch spool and having a second end with a winch line guide that keeps the second end of the swing arm in alignment with the winch line coming off the spool. In other embodiments, the bracket comprises a line guide that slides along a path equidistant from the winch spool and remains in alignment with the winch line coming off the spool. 
     The invention of the present disclosure, in another aspect thereof, comprises a method of determining line pull on a winch or similar device. The method includes measuring a first angle of a winch line relative to a central axis of a winch drum, measuring a second angle of the winch line relative to a spool of winch line on the drum, measuring a torque applied to the winch drum, and determining a force on the winch line based upon the measured first and second angle and the measured torque. 
     The method may also include providing first and second sensors proximate the winch line to determine first and second angles, respectively. Mounting the first and second sensors on an arm with one end fixed in relation to the winch spool may also be performed. In other embodiments, mounting the first and second sensors on a bracket moveable within a raceway at least partially surrounding the winch spool is included. 
     Another factor that makes it complicated is the angle at which the rope exits the winch or similar device. This angle can change according to where the load is located in relation to the winch or similar device. As the exit angle of the line changes, the place where the rope exits the winch or similar device moves relative to the center axis, causing X to change. 
     What is needed is a system and method for addressing the above and related concerns. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are to be read in conjunction with the reference numerals, which indicate like parts in the various views. 
         FIG. 1  is a perspective view of one embodiment of a winch system according to aspects of the present disclosure. 
         FIG. 2  is a perspective view of another embodiment of a winch system according to aspects of the present disclosure. 
         FIG. 3  is a perspective view of another embodiment of a winch system according to aspects of the present disclosure. 
         FIG. 4  is a diagram of the geometric relationship between various components of the winch systems of  FIGS. 1-3 . 
         FIG. 5A  side view of a winch system according to aspects of the present disclosure with an overlay showing the geometric relation between various components. 
         FIG. 5B  is another side view of a winch system according to aspects of the present disclosure with an overlay showing the geometric relation between various components when a quantity of winch line is present on the spool. 
         FIG. 6  is a block diagram of a line pull calculation system according to aspects of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to  FIG. 1 , a perspective view of a winch system  100  according to aspects of the present disclosure is shown. The winch  100  includes a winch drum  102  that may be provided with winch line  104 . The winch line  104  could be rope, cable, or another suitable material depending upon the application of the winch  100 . The cable  104  will be wrapped around and spool from the drum  102 . A winch motor  106  will provide the turning and/or braking force for the winch drum  102  that will allow loads to be manipulated via the winch line  104 . The motor  106  may be electric, hydraulic, or based upon other technology. In the present embodiment, the winch  100  is also provided with a torque sensor  108 . The torque sensor  108  serves to determine an amount of torque being applied to the drum  102  by tension on the winch line  104 . The torque sensor  108  may be based on a strain gauge, magnetics, slip rings, surface acoustic waves or other technologies. The torque sensor provides an electronic signal indicative of torque value at the drum. 
     It is understood that the components associated with the winch  100  may be mounted on or around support structures such as bracket  110 . This may allow the winch  100  to be mounted to a vehicle or a stationary location for use in lifting or manipulating loads. Attached to part of the support structure  110  associated with the winch  100  is a swing arm  116 . In the present embodiment, the swing arm  116  is attached to the support structure  110  only on a single end thereof. The opposite end provides a location for mounting a first angle sensor  112  and a second angle sensor  114 . The angle sensors  112 ,  114  may be solid state electronic sensors. The sensors  112 ,  114  provide an electronic signal that is indicative of the angle at which the sensor lies relative to a baseline (e.g., the sensor may provide the angle relative to horizontal). In the present embodiment, and as explained more fully below, the first angle sensor  112  is located and configured to measure the angle of the winch line  104  relative to the center of the drum  102 . The second angle sensor  114  is located and configured to measure the angle of the winch line  104  relative to the location where the line pulls away from, or exits from, the drum  102 . 
     Also mounted to the swing arm  116  is a line guide  118 . In the present embodiment, the second sensor  114  is actually mounted to the line guide  118 . The line guide  118  also serves to ensure that the angle sensors  112 ,  114  remain aligned with the winch line  104  as it exits the spool or drum  102 . As will be described in greater detail below, measurements taken by the angle sensor  112 ,  114  combined with measurements provided by the torque sensor  108  can be utilized to determine an amount of tensile force applied to the winch line  104 . 
     Referring now to  FIG. 2 , a perspective view of another embodiment of a winch system  100  is shown. It will be appreciated that many of the components of  FIG. 2  are shared with  FIG. 1 . For example, the system includes a drum  102  containing a supply of winch line  104 . A motor  106  provides turning and braking force to the drum  102 . The entire system may be mounted or affixed to various support brackets  110 . 
     As before, a first angle sensor  112  is provided in conjunction with a second angle sensor  114 . However, rather than being mounted by a swing arm, the sensors are attached to the winch  100  via brackets  202 . The brackets  202  also attach to the line guide  118 . The brackets  202  in the present embodiment are free to rotate or slide within a raceway  204 . The raceway in the present embodiment is defined on the support structure  110  of the winch  100  to allow the line guide  118  and sensors  112 ,  114  to rotate in a fixed relationship with respect to the drum  102 . The sensors  112 ,  114  will remain equidistant from the center of the drum  102  while being allowed to rotate about the center as the angle of the line  114  coming off the drum  102  changes. 
     Referring now to  FIG. 3 , yet another perspective view of a winch  100  according to aspects of the present disclosure is shown. The embodiment of  FIG. 3  is similar to the previous embodiments in that the major components of the winch itself, namely the drum  102 , winch line  104 , and motor  106 , are provided in substantially the same relationship. In the present embodiment, the sensors  112 ,  114  are also mounted so as to remain substantially in line with the winch line  104  as it exits the drum  102 . In the present embodiment, a cover  304  is provided to cover the drum  102 . In some embodiments, the cover may retract freely as the angle of the winch line  104  changes. A bracket  302  may be provided as part of the cover  304  for mounting of the first angle sensor  112 . The cover  304  may also provide a mounting location for the line guide  118 . The line guide  118  may now be second angle sensor  114 . 
     Referring now to  FIG. 4 , a diagram of the various angles involved in the deployment of the winch line  104  from the drum is shown. For purposes of the present discussion, the location labeled “P” is the location of the second angle sensor  114 . This sensor measures the angle denoted “K”, which is the angle of the winch line relative to the location on the winch drum or spool where the line pulls away. Since the sensor P is located on the line guide  118  and is always substantially in line with the winch line  104 , it can be configured to consistently provide a measurement of the angle of the winch line  104  as it exits the drum  102 . Sensor  112 , located at location B, can be configured to indicate the angle of the winch line  104  relative to the center of the drum  102 , denoted “C”. This is denoted as angle “D”. Location “B”, or first sensor  112 , will remain at a constant distance “L” from the center C of the drum  102 . As the winch line  104  is wound and unwound from the drum  102 , the distance “X” from center C to exit point A will vary. It is the distance X which can be calculated using the system described in the present disclosure. 
     Referring now to  FIG. 5A  a side view of a winch system according to aspects of the present disclosure is shown with an overlay of the geometric relation between various components.  FIG. 5  illustrates the angles and relationships described with respect to  FIG. 4  as applied to a winch system as previously described. It can be seen that C is at the center of the winch drum  102 . The first sensor  112  lies a constant distance L from the center C at location B. The second sensor  114  is at location P on the line guide  118 . 
     The first sensor  112  measures the angle of the winch line at point B, relative to the center of the drum C. Sensor  112  provides the angle as displacement from the horizontal (e.g., horizontal being zero). The second sensor  114  measures the angle of the winch line from the location A (where it leaves the drum) also relative to the horizontal. 
     It will be appreciated that the distance X, the distance from A to the center of the drum  102  will vary depending upon the amount of winch line spooled onto the drum  102 .  FIG. 5B  illustrates the geometric relation between various components when a quantity of winch line is present on the drum  102 . Here a spool of line  502  is wrapped around the drum  102 . This has altered the distance X from the center C of the drum  102  to the location A where the line  104  exits the spool  502 . In other words, X is the distance from the center of the drum  102  to a working surface  504  of the spool  502 . 
     Using the measured angles K and D, angle G ( FIG. 4 ) can be determined: G=D−K. The sine of angle G is equal to the distance X divided by the distance L. In other words sin(G)=X/L. Rearranging this equation yields X=(sin(G))/L. G is computed as described. The distance L remains constant since it is the distance from sensor  112  to the very center C of the drum  102 . Therefore using the measured angles K and D, the distance X can be determined. Torque on the winch drum  102  is the force applied to the winch line  102  multiplied by the distance X. X is now known and the torque is measured. Hence the winch line pull can be computed: F=torque/X. 
     Referring now to  FIG. 6  is a block diagram of a line pull calculation system according to aspects of the present disclosure is shown. Here a computer  602  receives the input from torque sensor  108 , and angle sensors  112 ,  114 . As described the computer  602  calculates the line pull. This may be displayed on display unit  604 . Various methods of communicating the torque and angles to the computer  602  may be implemented. The signals may be analog or digital and may be provided individually or on a common bus. In some embodiments, the signals are communicated wirelessly to the computer  602 . The computer  602  may be a solid state computer or a device using a combination of solid state circuitry and electro-mechanical devices. The computer may be specific to the system described herein or it may be part of a large control computer on a vehicle or within a plant or similar. The display unit  604  may be segment based on part of a graphical display system. It may be dedicated to the winch system  100  or it may be part of a larger display system. 
     Thus, the present invention is well adapted to carry out the objectives and attain the ends and advantages mentioned above as well as those inherent therein. While presently preferred embodiments have been described for purposes of this disclosure, numerous changes and modifications will be apparent to those of ordinary skill in the art. Such changes and modifications are encompassed within the spirit of this invention as defined by the claims.