Abstract:
A power assisted winch and method include a control system and method for detecting the amount of turning force or torque supplied by a manual input drive to the winch drum, supplying turning force or torque from a motor to the winch drum and controlling the amount of torque supplied by the motor to the winch drum as a function of the amount of turning force or torque supplied by the manual drive. The function may be a fixed predetermined ratio or it may vary depending upon the level of turning force or torque supplied by the manual input drive. A torque sensor may be utilized to detect the level of input manual torque and control apparatus controls the amount of torque supplied by the motor to gearing or coupling driving the winch drum.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a power assisted winch and method. More particularly, the present invention relates to a winch which may include a manual drive and power assistance to the manual drive in some ratio to the manual drive input which will allow the user to maintain some “feel” of the force being applied to the line being controlled by the winch drum. 
       BACKGROUND OF THE INVENTION 
       [0002]    Winches find widespread use in various applications. One important and widespread area of use of winches today is for pulling in lines attached to sails and anchors on sailboats and other boats. However, winches find various other applications including use on recreational vehicles and in industrial applications. 
         [0003]    In the past, winches were known to be operated manually by a winch handle or crank which drove the winch usually through gearing. More recently, applications of motors have been utilized to drive winches, such as electric motors. However, these suffer from various deficiencies including the fact that the winch is either full on or full off. In other words, by pressing a button or actuating a switch, the winch is on and would operate at full speed. By releasing the button or deactivating a switch, the winch would be turned completely off. 
         [0004]    Recently, there has been a disclosure of a winch in which the speed of the winch could be varied by utilizing an electric motor to a direct current electric motor operated or controlled by a pulse width modulator and potentiometer. For example, see WO 02/24567 A1 which discloses a variable-speed drive assembly for a winch for a water vessel such as a yacht which includes an electric motor controlled by a pulse-width modulator and potentiometer. 
         [0005]    However, none of the prior art provides a means wherein a winch may be manually operated with power assistance, thereby providing the operator with a “feel” of the force being applied to the line and the conditions of the line, sail, anchor or other load on the line. 
       SUMMARY OF THE INVENTION 
       [0006]    One advantage of the present invention is that it provides a winch which may be manually operated, but with power assistance. The winch of the present invention may also be operated purely manually or solely by motor drive. 
         [0007]    An advantage of the present invention is that it provides the operator with a “feel” of the amount of load on the line and the amount of force being applied to the line without the operator supplying the full force manually. 
         [0008]    Briefly and basically, in accordance with the present invention, a winch includes a winch drum and a manual input drive for applying a turning force or torque to the winch drum. A motor for supplying a turning force or torque to the winch drum is also provided. A controller for selectively controlling the amount of turning force or torque supplied by the motor to the winch drum is provided to provide assistance to the manual input. 
         [0009]    In a presently preferred embodiment, a sensor senses at least the amount of manually supplied input torque and provides a control signal to the motor for supplying torque as a function of the manual input torque. This function of the input turning force or torque may be a fixed ratio of the input torque or the amount of torque supplied by the motor may vary as a function of the amount of input torque. In other words, for low torque manual input, the amount of torque supplied by the motor may be a smaller ratio than when a large manual input torque is applied. 
         [0010]    However, it is understood that the input turning force or torque could be determined by measuring the motor torque and total output torque, taking the difference as the input torque. In other words, input+motor=total output. By measuring any two of these turning forces or torques, the third can be computed. 
         [0011]    The present invention includes both the winch apparatus and the method of supplying the combination of manual and motor torque to the gearing for driving the winch drum. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown. 
           [0013]      FIG. 1  is a schematic diagram of a power assisted winch in accordance with the present invention. 
       
    
    
       [0014]    It is emphasized that  FIG. 1  is a schematic diagram of the present invention. The input crank handle may be concentric with the winch drum, and often is. However, in other embodiments, the manual input drive may be separate from the winch drum. Further, the input and output shafts may be parallel and separated as shown, or at right angles to one another, or coaxially located, or in another configuration. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    Referring now to the drawings, wherein like numerals indicate like elements, there is shown in  FIG. 1  a schematic diagram of a power-assisted winch in accordance with the present invention. As described above, the winch of the present invention may preferably be utilized on sailboats to haul in sails and haul up anchors or the like, but finds application in many other areas. 
         [0016]    Referring to  FIG. 1 , there is shown a schematic diagram of a winch  10  in accordance with the present invention. Winch  10  includes a winch drum  12  driven by gearing or other coupling  14 . A winch handle or crank  16  provides a manual input drive for applying torque to the gearing or other coupling  14 . Although gearing is a presently preferred embodiment, it is understood that the inputs to the winch drum may be coupled in other manners. For Examiner, it is possible to directly couple the input shaft to the drum, and this may be done for small winches or it may be possible to use other means of coupling such as cogged belts and the like. Manual input drive  16  supplies a turning force or torque via upper shaft  18  and lower shaft  20 . Upper shaft  18  and lower shaft  20  are coupled together by torque sensor  22 . 
         [0017]    Input torque sensor  22  measures the force applied by the user to input shaft  18  via winch handle  16 . Torque sensor  22  may comprise an inner hub and an outer hub separated by four button load cells, such a model S400 made by Strain Measurement Devices, 130 Research Parkway, Meriden, Conn. 06450. The inner hub may be coupled to the upper shaft  18  and the outer hub may be coupled to the lower shaft  20 . The load cells may be positioned between the hubs in such a way that clockwise rotation of the upper input shaft applies compression force to two of the load cells. Counterclockwise rotation applies compression force to the two other load cells. The signals from the load cells may be carried from the rotating torque sensor by slip ring couplings, such as those made by Moog, Inc., Jamison Road, East Aurora, N.Y. 14052. The output of the manual input drive torque sensor  22  is supplied via line  24  to winch controller  26 . 
         [0018]    Although in a presently preferred embodiment, an input torque sensor  22  may be utilized, it is understood that other means of measuring the torque or turning force may be provided. For example, a load cell may be located in the arm of crank  16  which senses the turning or bending force applied to the input handle. The force on the input handle multiplied by the handle length provides a measure of the torque. In this manner, the torque may be determined by measuring the bending force applied to the handle multiplied by the handle length. Alternatively, the input turning force or torque may be determined from measurement of the motor force and the total output force provided by the drum. Total output force applied to the drum may be measured by measuring the strain on sensors located in mountings between the base of the drum assembly and the yacht or other mounting structure. 
         [0019]    Additional turning force or torque is supplied to gearing or coupling  14  and lower shaft  20  via servo motor  28 . Servo motor  28  supplies turning force or torque via gearing or coupling  30  and  32  to lower shaft  20 , gearing or coupling  14  and winch drum  12 . Servo motor  28  is provided with an encoder  34  which supplies motor, speed and direction signals via line  36  to servo motor controller  38 . Motor drive power is supplied via line  40  by servo motor controller  38  to servo motor  28 . 
         [0020]    Servo motor  28  may preferably be a brushless AC motor with a built-in Hall-effect encoder  34 . The motor may be a three-phase synchronous permanent magnet motor with its speed being controlled by the frequency of the its sinusoidal input power. The torque of servo motor  28  is determined by the current applied to it. One motor that meets these requirements and may be used in the system is the SVM-220 sold by Automation Direct, 3505 Hutchinson Road, Cumming, Ga. 30040. 
         [0021]    Servo motor controller  38  may convert 12 or 24 volt DC power from a boat&#39;s batteries into three-phase AC power to drive servo motor  28 . This is particularly the case where the winch is not used with AC power readily available. Servo motor controller  38  receives digital torque and direction command from a microprocessor in winch controller  26  via line  42 . This input from winch controller  26  via line  42  causes servo motor  28  to run at the commanded turning force or torque level. Servo motor controller  38  also measures the motor speed and reports the speed via line  44  in the form of a digital signal to a microprocessor in winch controller  26 . 
         [0022]    Winch controller  26  includes a microprocessor based logic circuit which has several functions, including maintaining a predetermined relationship between the input turning force or torque and motor turning force or torque by sending turning force or torque commands to servo motor controller  38 . It also filters variations in the output turning force or torque command using the winch speed and turning force or torque reported by the servo motor controller in order to provide smooth response to changes in user&#39;s input force. 
         [0023]    Winch controller  26  may be a self programmable logic controller (PLC) such as the DirectLogic 05 sold by Automation Direct, 3505 Hutchinson Road, Cumming Ga. 30040. The winch controller algorithm may be stored in a non-volatile ROM (read-only memory) on the winch controller. 
         [0024]    The winch  10  may be operated in three different operating modes, including (1) complete manual operation; (2) power-assisted operation and (3) full-power operation. 
         [0025]    During manual operation, the operator applies a turning force to the winch handle  16  and this force is transmitted through upper shaft  18  and lower shaft  20  and gearing or coupling  14  to winch drum  12 . The motor is electrically disconnected from the motor controller so that no power assistance is applied. This is an optional feature of the present invention. 
         [0026]    During power assisted operation, force from the motor is added to the force applied by the user. This force may be applied in a ratio which is a function of the input force. This may be referred to as a target ratio. The target ratio may be fixed or predetermined or it may vary depending upon the input conditions, such as the amount of input force. For example, the ratio of input force to output force may be fixed. That is, the motor could always apply five times or some other predetermined amount of the input force, or it may be variable. For example, the ratio could be low at low manual input force and high at higher manual input force. This would provide better “feel” at low loads, while maintaining the ability to apply high amounts of force when the load is high. The power assistance in the ratio is controlled by winch controller  26 . Winch controller  26  may be programmed to provide a fixed ratio or a ratio on a predetermined function of input force. 
         [0027]    When an input turning force is applied manually to the winch handle  16 , winch controller  26  monitors the input torque reported by input torque sensor  22  and the motor output torque reported by servo motor controller  38 . Winch controller  26  computes the ratio of the input and torque measurements. This is the measured ratio. The winch controller  26  then compares the measured ratio to the target ratio. When the target ratio is higher than the measured ratio, not enough power assistance is being applied, so winch controller  26  commands the servo motor controller  38  to increase the motor torque. Conversely of the measured ratio is higher than the target ratio, too much power is being applied and the winch controller commands the servo motor controller  28  to reduce the motor torque. The manual and motor forces are combined and drive the winch drum through gearing or coupling  14 . If the load on the winch increases, the winch will stop unless additional force is applied to the winch handle. This behavior mimics that of a conventional manual winch and provides the “feel” of the load on the line being worked by winch drum  12 . 
         [0028]    During full power operation, only the motor applies force to the winch. The winch handle  16  may be removed and no manual power is applied. The user initiates operation by actuating a switch or button located near the winch such as switch buttons  46  and  48 . Winch controller  26  commands servo motor controller  38  to smoothly accelerate the motor to a predetermined speed. When the user releases the button switch  46  or  48 , the winch controller commands the servo motor to stop the motor. Two switches are provided, one operates the input of the winch in one direction for high speed and low torque and one operates the input of the winch in the other direction for low speed and high torque. This change of speed and power is set by the winch gearing or coupling. The winch drum always turns in the same direction and the industry standard is conventionally clockwise. Usually, the gear or coupling ratio depends upon the direction of rotation of the input crank for a manual winch. 
         [0029]    It is understood that other types of motors such as brush DC motors may be used which are controlled by varying the input current. This may be done by using pulse width modulation in which the line voltage is switched off and on very rapidly in order to modulate the amount of current sent to the motor. The longer each pulse lasts, the more current flows to the motor and hence the more power it will produce. It is possible to use a DC brush motor in this application, but it is currently preferred that an AC motor be used as it is believed that it offers better control for rapid changes in direction and force. 
         [0030]    The components of the winch may be housed inside winch drum  12  in a sealed casing below the mounting surface. 
         [0031]    In accordance with the present invention, the power assistance may work in both the clockwise and counterclockwise directions, enabling the winch to operate at two different direction-dependent speeds set by the gearing or coupling. The motor may be electric or hydraulic. The winch handle and the motor may be in series or in parallel. Although described in electrical context, the torque sensors and winch controller may be mechanical, electrical, hydraulic or a combination of all three. 
         [0032]    Because of the torque multiplication, a shorter winch handle may be used, reducing arm and shoulder motion required. Typical winch handles are 8 to 10 inches long and a 4 to 6 inch handle may be utilized in the present invention in power assist mode. Further, the torque sensors need not measure the torque directly. For example, the output torque of the motor may be computed based upon the input power and speed. The output torque of the motor can also be measured indirectly by subtracting the input torque from output torque of the entire winch. 
         [0033]    In accordance with the method of the present invention, a winch may be driven by providing a manual input drive and a motor input drive wherein the amount of assistance by the motor is varied as a function of the amount of input torque supplied. This may be a fixed ratio or it may be a function of the level of manual input torque. In other words, the ratio may be smaller at low levels of manual input torque providing better “feel” and the ratio of motor torque supplied at high levels of input torque may provide the ability to provide increased force on the line. 
         [0034]    The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.