Abstract:
The invention provides a winch and method for raising and lowering a boat anchor attached to an anchor rope, comprising: an electric motor ( 10 ) operable to turn the winch in a rope raising direction or a rope lowering direction and powered from a power source supplying a supply voltage; and a boost controller (CB 1 - 3, S 1 - 2, K 1 - 6, Kx 1 - 4,25,30 ) for applying a boosted voltage higher than the supply voltage to the motor ( 10 ) so as to increase a turning speed of the motor when the motor is operating in the rope lowering direction.

Description:
FIELD 
       [0001]    The present invention relates to boat anchor winches typically used in pleasure craft and other water vessels, and in particular to an improved motorized winch. 
       BACKGROUND 
       [0002]    Electrically powered boat anchor winches are a common labour saving device on pleasure craft. The simplest and cheapest form involves a winch with a single speed DC electric motor wired into a 12V or 24V battery for raising and lowering the anchor. 
         [0003]    A disadvantage of this simple form is that it takes much longer to deploy the anchor than with a manual winch, as the safe speed for raising the anchor is much slower than the safe speed for lowering the anchor. 
         [0004]    A solution known in the art is to incorporate a clutch release mechanism, whereby the motor can be disengaged and anchor can be allowed to drop to the ocean floor unhindered by the motor speed. Such mechanisms add considerable cost and complexity and can be unreliable. 
         [0005]    Variable or multiple speed electric winches are known, but prior art variable speed winches either utilize complex gears or operate only to variably reduce the voltage applied to the motor from the 12V battery. In such devices the variable speeds are typically used for the purpose of reduction of the maximum raising speed for certain tasks. 
         [0006]    There is therefore a need for an improved approach to the provision of rapid anchor lowering in an electrically powered boat anchor winch. 
         [0007]    The inventors have realized that a relatively inexpensive and highly reliable controller can be added to a simple one speed electric winch to provide reliable rapid anchor lowering. 
       SUMMARY OF THE INVENTION 
       [0008]    According to a first broad aspect of the invention there is provided a winch for raising and lowering a boat anchor attached to an anchor rope comprising: 
         [0009]    an electric motor operable to turn the winch in a rope raising direction or a rope lowering direction and powered from a power source supplying a supply voltage; and 
         [0010]    a boost controller for applying a boosted voltage higher than the supply voltage to the motor so as to increase a turning speed of the motor when the motor is operating in the rope lowering direction. 
         [0011]    In one embodiment, the voltages are DC voltages. 
         [0012]    In one embodiment, the winch further comprises a selector switch to enable or disable the boosted voltage. 
         [0013]    In one embodiment, the boosted voltage is produced with the aid of a boost converter. The boost controller may further comprise a motor speed controller electrically connected between the boost converter and the motor. The motor speed controller may further comprise a potentiometer for user adjustment of the boosted voltage. 
         [0014]    In one embodiment, the boost controller may further comprise a soft start circuit to enable smooth engagement of the boosted voltage to the motor on startup. The soft start circuit may be integral with the motor speed controller. 
         [0015]    In one embodiment, the boost controller is unable to apply the boosted voltage when the motor is operating in the rope raising direction. 
         [0016]    In one embodiment, the power source is a 12V or 24V DC battery. 
         [0017]    According to a second broad aspect of the invention there is provided a method of providing a motorized anchor winch powered from a power source supplying a supply voltage with the capability of lowering the anchor faster than raising the anchor, the method comprising the step of applying a boosted voltage higher than the supply voltage to the motor when the motor is operating in a rope lowering direction. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  is a diagram of a typical motorized boat anchor winch to which the invention may be applied; 
           [0019]      FIG. 2  is a circuit diagram of a control circuit part of a boost controller in accordance with an embodiment of the invention. 
           [0020]      FIG. 3  is a circuit diagram of a power circuit adapted to operate with the control circuit of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0021]    An embodiment of the current invention will now be described. 
         [0022]    Referring first to  FIG. 1 , an electrically operated boat anchor winch is shown, as included in embodiments of the invention. 12 V DC electric motor  10  rated at 1000 Watts power output has electrical power input lead  11 . Motor  10  drives worm drive gearbox  13  mounted on bracket  14 . Bracket  14  has number of attachment points such as  17 ,  18  for mounting to the boat by screws. Mounted on bracket  14  by bearings and turned by an output shaft of gearbox  13  is a winch drum with spindle  15 ,  16  around which the anchor rope is wound and unwound. 
         [0023]    Referring now to  FIGS. 2 and 3 , the boost controller of an embodiment of the invention is exemplified, divided into a control circuit ( FIG. 2 ) and a power circuit ( FIG. 3 ). Labels + and − denote connection to the positive and negative terminals of a 12 V DC battery. Control sides of a relay are labelled with a rectangle with a diagonal line, and controlled sides as a switch in a normally closed or normally open position. 
         [0024]    Circuit breaker CB 3  (5 A) protects the control circuit and circuit breaker CB 1  (50 A) protects the power circuit. Up-down switch S 1  operates to switch the motor between a rope raising direction in position U and a rope lowering direction in position D. 
         [0025]    When S 1  is in position U, interlock relay Kx 2  (3 A, 12V) is energized to open its normally closed switch, disconnecting the down control circuitry. Similarly, interlock relay Kx 1  is de-energized and its normally-closed switch is kept closed. Relays K 1  and K 2  (60 A, 12V) are therefore energized, closing their normally open switches and presenting 12V across motor  10  in an anchor raising polarity. 
         [0026]    When S 1  is in position D, the converse applies with the interlock relays and the down control circuitry operates. If switch S 2  (manually operable by the user) is in the bypass B position, the boosting circuitry is disabled, K 5  and K 6  (12V, 60 A, normally open) being energized and closed and presenting 12 V across motor  10  in an anchor-lowering polarity. If switch S 2  is in the fast fall F position, the boosting circuitry is enabled with K 3  and K 4  energized (60 A, 12V, normally open), applying 12V across the inputs of 12V to 24 V (15 A) DC to DC boost (step up) converter  25 , as are isolation relays Kx 3  and Kx 4  (12VDC, 30 A, normally open), applying the voltage output from motor speed controller  30  through circuit breaker CB 2  (20 A) across motor  10  in an anchor lowering polarity. 
         [0027]    Motor speed controller  30  is a standard motor speed controller (12V-36V DC, 50 A) that can supply a reduced voltage by pulse width modulation, to which may be fitted a potentiometer for the user to adjust the pulse width and hence the boosted voltage downwards from 24V, so as to suit the particular anchor. Ideally, the boosted speed is as fast as is allowable so that the anchor falls without slackening of the anchor rope and potential tangling. Typically, the user will adjust the potentiometer once on installation and thereafter use the switch S 2  to enable the boosted speed. A second advantage of the motor speed controller  30  is that it incorporates a soft start capacitor circuit that enables smoothed engagement of the applied voltage to the motor over 1-3 seconds, reducing the high current on startup which otherwise can damage the boost converter. 
         [0028]    By providing a boosted voltage to the motor when operating in the rope lowering direction, equivalent functionality to a clutch arrangement can be provided without mechanical modification or mechanical enhancement of a single speed base model winch, increasing simplicity and providing increased reliability over a clutch. Electric motors rated for 12 V operation in the rope raising (loaded) condition are well able to operate faster with 24 V input, particularly when this is applied in the rope lowering condition, which is unloaded or negatively loaded by the weight of the anchor. 
         [0029]    Persons skilled in the art will also appreciate that many variations may be made to the invention without departing from the scope of the invention. 
         [0030]    For example, the invention applies to anchor motors of various sizes and powers and normal operating voltages, including but not limited to 12V and 24 V DC systems and also AC systems. Also, although it is preferred to provide the voltage boost only in the rope lowering direction, other embodiments can also provide the voltage boost in both rope raising and lowering directions. 
         [0031]    In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 
         [0032]    It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.