Abstract:
A propeller for a marine propulsion system is disclosed which comprises a propeller hub having a casing formed from three segments ( 16   a,    16   b,    16   c ), each of which has a part of an opening ( 28 ) for mounting a propeller blade ( 34 ). A locking and unlocking mechanism ( 51, 54, 95, 100 ) is provided for disengaging the propeller blades to enable pitch adjustment of the blades. A push rod ( 50 ) is connected to the mechanism ( 100 ) to cause disengagement and adjustment of the pitch of the blades. The mechanism ( 100 ) includes a claw ( 101 ) having pivotally connected fingers ( 95 ). The hub also has a slide ring ( 51 ) having a load surface ( 61 ) is provided for receiving load when the propeller blades are unlocked to enable pitch adjustment to take place.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a variable pitch propeller for a marine propulsion system. The invention is an improvement to that disclosed in our International Application No. PCT/AU2004/001721. The contents of that International application are incorporated into this specification by this reference. 
       BACKGROUND ART 
       [0002]    Marine propulsion systems generally comprise outboard motors or stern drive systems which transmit rotary power to a propeller to drive a boat through water. The propeller includes propeller blades which are angled to provide propulsion through the water. The angle or pitch of the blades relative to a radial axis transverse to the drive axis of the propeller is generally fixed and selected to provide maximum efficiency at maximum speed or cruise speed of the boat to which the system is used. The pitch is generally less efficient at take-off when the boat is driven from stationary up to the cruise speed, which inefficiency results in increased fuel consumption and a longer time for the boat to move from the stationary to cruise speed. If the propeller has too large pitch, the power of the engine may not be sufficient to accelerate the boat to planing speed. 
         [0003]    In order to overcome this problem, variable pitch propeller systems have been proposed in which the pitch of the propeller blades can be altered to suit the changing operating conditions of the propulsion system. 
         [0004]    Our aforementioned International application discloses a propeller which successfully addresses the above problems. 
       SUMMARY OF THE INVENTION 
       [0005]    The object of the present invention is to provide a propeller which provides still further advantages over conventional variable pitch propeller systems. 
         [0006]    The invention provides a variable pitch propeller for a marine propulsion system, comprising: 
         [0007]    a propeller hub having a plurality of openings, and a hub surface surrounding each opening; 
         [0008]    a propeller blade having a propeller base mounted in each of the openings, each base having a base surface for engaging the hub surface of the respective opening; 
         [0009]    an unlocking mechanism for disengaging the respective base surface of the base from the respective hub surface of the hub for enabling rotation of the hub about an axis transverse to a rotation axis of the hub; 
         [0010]    a pitch adjusting mechanism for rotating each base to thereby adjust the pitch of the propeller blade; 
         [0011]    a propeller hub casing formed from a plurality of separate segments, each of the segments having a part of one of said plurality of openings, and said segments being couplable together to form the propeller hub casing. 
         [0012]    By providing a propeller hub casing formed from a plurality of segments, the assembly of the unlocking mechanism and pitch adjusting mechanism within the hub is easier, thereby improving the ease of manufacture and reducing manufacturing costs. 
         [0013]    Preferably the hub segments are arcuate in shape so that when the hub segments are coupled together, their outer surfaces form a cylinder, each segment having a tongue at one end and a cut-out at the opposite end, the cut-out defining at least one lug, the tongue and the at least one lug having a bore, and wherein the tongue of one segment engages in the cut-out of an adjacent segment so that the bores in the tongue and lug align, and a pin located through the aligned bores to couple the segments together to form the hub casing. 
         [0014]    Preferably the cut-out is arranged at a midpoint of one end and defines a pair of spaced apart lugs, each having an aligned bore. 
         [0015]    Preferably the unlocking mechanism comprises a mechanical unlocking mechanism. 
         [0016]    Preferably the propeller further comprises a mechanical re-locking mechanism for allowing re-engagement of the respective base surface of the base with the respective hub surface of the hub to lock the base in the pitch adjusted position. 
         [0017]    Preferably the unlocking mechanism and the re-locking mechanism comprise a common locking and unlocking mechanism. 
         [0018]    Preferably the re-locking mechanism allows re-engagement of the base surface with the hub surface by virtue of centrifugal force during operation of the propeller after the pitch adjusting mechanism has adjusted the pitch of the propeller blades. 
         [0019]    Preferably the common locking and unlocking mechanism comprise a stem forming part of each base, a respective eccentric coupled to each stem, a respective pin mounted to each eccentric, a push rod for moving the pins to in turn rotate the eccentrics so that the eccentrics push the stems, and therefore the bases, radially inwardly with respect to the hub to unlock the base by removing load from the hub surface and base surface, and after the pitch of the propeller blades have been adjusted, re-applies the load to the surfaces to re-engage the respective base surface of the bases with the respective hub surfaces of the openings to re-lock the bases and therefore the propeller blades in the pitch adjusted position. 
         [0020]    Preferably the mechanical unlocking mechanism disengages the respective base surface from the respective hub surface by transferring load from the base surface and hub surface to thereby allow the hub surface and base surface to move relative to one another. 
         [0021]    Preferably the propeller base comprises a stem of the propeller blade and a base ring located on the stem, the base ring having the base surface. 
         [0022]    Preferably the hub surface is formed on a hub ring which defines a part of a respective opening and which receives the base surface. 
         [0023]    Preferably the base surface and hub surface are inclined surfaces which taper inwardly from a radially outermost edge of the surface to a radially most inner edge of the surfaces. 
         [0024]    Preferably the unlocking mechanism comprises an eccentric, a slide ring having a slide surface mounted on the eccentric, the slide ring being arranged radially inwardly of the respective hub surface and base surface and located in a shoulder in the base ring so that when the eccentric is rotated, load is transferred from the respective hub surface and base surface to the hub ring and slide surface so the respective propeller blades can be adjusted after the transfer of load with the hub ring sliding on the slide surface. 
         [0025]    Preferably the eccentric is coupled to a pin for firstly rotating the eccentric about a first axis to transfer the load and then rotating the eccentric about a second axis transverse to the first axis to rotate the respective propeller blade to adjust the pitch of the propeller blade. 
         [0026]    Preferably the hub surface and the base surface are inclined cone-shaped surfaces. 
         [0027]    Preferably the push rod is coupled to a claw which has a respective finger for each of the propeller blades, each finger being mounted to a respective pin by a socket and eye joint. 
         [0028]    Preferably the fingers are pivotally coupled to the arms for pivotal movement relative to the arms. 
         [0029]    The invention also provides a variable pitch propeller for a marine propulsion system, comprising: 
         [0030]    a propeller hub having a plurality of openings, and a hub surface surrounding each opening; 
         [0031]    a propeller blade having a propeller base mounted in each of the openings, each base having a base surface for engaging the hub surface of the respective opening; 
         [0032]    a pitch adjusting mechanism for adjusting the pitch of each of the propeller blades about an axis perpendicular to a rotation axis of the hub, the mechanism including a plurality of generally radially extending arms, each arm carrying a finger, a pivotal coupling between the finger and the respective radially extending arm for allowing pivotal movement of the fingers with respect to the arms; and 
         [0033]    the arms being coupled to the propeller blades so that upon longitudinal movement of the arms in the direction of the axis of rotation of the hub, the pitch of the propeller blades is adjusted. 
         [0034]    By making the arms pivotally connected to the fingers, the transfer of motion from the arms to the fingers and then to adjust the pitch of the propeller blades is smoother and involves no sliding action of the end of the fingers remote from the pivotal coupling, thereby providing more reliable pitch adjustment. 
         [0035]    Preferably the hub has a hub casing formed from segments which are arcuate in shape so that when the hub segments are coupled together, they form a cylinder, each segment having a tongue at one end and a cut-out at the opposite end, the cut-out defining at least one lug, the tongue and at least one lug having a bore, and wherein the tongue of one segment engages in the cut-out of the adjacent segment so that the bores in the tongue and lug align and a pin located through the aligned bores to couple the segments together to form the hub casing. 
         [0036]    Preferably the cut-out is arranged at a midpoint of one end and defines a pair of spaced apart lugs, each having an aligned bore. 
         [0037]    Preferably the pitch adjusting mechanism has a mechanical unlocking mechanism. 
         [0038]    Preferably the propeller further comprises a mechanical re-locking mechanism for allowing re-engagement of the respective base surface of the base with the respective hub surface of the hub to lock the base in the pitch adjusted position. 
         [0039]    Preferably the unlocking mechanism and the re-locking mechanism comprise a common locking and unlocking mechanism. 
         [0040]    Preferably the re-locking mechanism allows re-engagement of the base surface with the hub surface by virtue of centrifugal force during operation of the propeller after the pitch adjusting mechanism has adjusted the pitch of the propeller blades. 
         [0041]    Preferably the common locking and unlocking mechanism comprise a stem on each base, a respective eccentric coupled to each stem, a respective pin mounted to each eccentric, a push rod attached to a claw which carries the arms and the fingers for moving the pins to in turn rotate the eccentrics so that the eccentrics push the stems, and therefore the bases, radially inwardly with respect to the hub to unlock the base by removing load from the hub surface and base surface, and after the pitch of the propeller blades have been adjusted, re-applies the load to the surfaces to re-engage the respective base surface of the bases with the respective hub surfaces of the openings to re-lock the bases and therefore the propeller blades in the pitch adjusted position. 
         [0042]    Preferably the mechanical unlocking mechanism disengages the respective base surface from the respective hub surface by transferring load from the base surface and hub surface to thereby allow the hub surface and base surface to move relative to one another. 
         [0043]    Preferably the propeller base comprises a stem of the propeller blade and a base ring located on the stem, the base ring having the base surface. 
         [0044]    Preferably the hub surface is formed on a hub ring which defines a part of a respective opening and which receives the base surface. 
         [0045]    Preferably the base surface and hub surface are inclined surfaces which taper inwardly from a radially outermost edge of the surface to a radially most inner edge of the surfaces. 
         [0046]    Preferably the unlocking mechanism comprises an eccentric, a slide ring having a slide surface mounted on the eccentric, the slide ring being arranged radially inwardly of the respective hub surface and base surface so that when the eccentric is rotated, load is transferred from the respective hub surface and base surface to the hub ring and slide surface so the respective propeller blades can be adjusted after the transfer of load with the hub ring sliding on the slide surface. 
         [0047]    Preferably the eccentric is coupled to a pin for firstly rotating the eccentric about a first axis to transfer the load and then rotating the eccentric about a second axis transverse to the first axis to rotate the respective propeller blade to adjust the pitch of the propeller blade. 
         [0048]    Preferably the hub surface and the base surface are inclined cone-shaped surfaces. 
         [0049]    Preferably each finger is mounted to a respective pin by a socket and eye joint. 
         [0050]    The invention also may be said to reside in a variable pitch propeller for a marine propulsion system, comprising: 
         [0051]    a propeller hub; 
         [0052]    a plurality of openings in the hub, each for receiving a respective propeller blade; 
         [0053]    a hub ring for each of the propeller blades, the hub rings each forming a part of a respective said opening and having a hub surface; 
         [0054]    a base ring on each propeller blade and having a base surface for engaging a respective hub surface; 
         [0055]    a slide member having a load surface; 
         [0056]    a locking and unlocking mechanism for unlocking the propeller blade by transferring load from the base surface and hub surface to the base ring and load surface to unlock the blades and for locking the blades by retransferring load to the base surface and hub surface after the propeller blade has been adjusted in pitch; and 
         [0057]    a pitch adjusting mechanism for rotating the blades about transverse axes with respect to the axis of rotation of the propeller when the propeller is in the unlocked condition and the load has been transferred to the base ring and load surface. 
         [0058]    Preferably the slide member comprises a slide ring and has a radially outer surface which forms the load surface for engaging a surface on the base ring so that load is taken by the base ring and load surface when the propeller blade is unlocked. 
         [0059]    Preferably the base surface and hub surface are inclined conical surfaces. 
         [0060]    Preferably the unlocking mechanism and the re-locking mechanism comprise a common locking and unlocking mechanism. 
         [0061]    Preferably the re-locking mechanism allows re-engagement of the base surface with the hub surface by virtue of centrifugal force during operation of the propeller after the pitch adjusting mechanism has adjusted the pitch of the propeller blades. 
         [0062]    Preferably each propeller blade has a base which includes the base ring, the common locking and unlocking mechanism comprise a stem on each base, a respective eccentric coupled to each stem, a respective pin mounted to each eccentric, a push rod attached to a claw which carries the arms and the fingers for moving the pins to in turn rotate the eccentrics so that the eccentrics push the stems, and therefore the bases, radially inwardly with respect to the hub to unlock the base by removing load from the hub surface and base surface, and after the pitch of the propeller blades have been adjusted, re-applies the load to the surfaces to re-engage the respective base surface of the bases with the respective hub surfaces of the openings to re-lock the bases and therefore the propeller blades in the pitch adjusted position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0063]    A preferred embodiment of the invention will be described, by way of example, with reference to the accompanying drawings in which: 
           [0064]      FIG. 1  is an exploded view of a hub according to the preferred embodiment of the invention; 
           [0065]      FIG. 2  is a cross-sectional view through one of the propeller blades showing the mechanical unlocking mechanism and pitch adjustment mechanism in an assembled condition; and 
           [0066]      FIG. 3  is a view of part of  FIG. 2  on an enlarged scale. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0067]    With reference to  FIGS. 1 and 2 , a propeller hub  10  is shown. The hub  10  is driven by a drive shaft in the manner which is described in detail in the aforementioned International application. Unlocking of the propellers and pitch adjustment is controlled by a push rod  50  which is concentrically arranged within the drive shaft (not shown). The drive shaft (not shown) engages in splines provided in hub end  12  for rotating the hub  10  about a longitudinal axis shown by dashed line A. 
         [0068]    Propeller blades  34  are provided which are adjustable in pitch about axes Y which are perpendicular to the axis A so as to adjust and set the pitch of the propeller blades  34  depending on the operating conditions of the boat and motor (not shown) which drives the drive shaft (not shown). 
         [0069]    The hub  10  has a rear hub end  14  and a hub casing formed from three segments  16   a ,  16   b  and  16   c . The segments are each arcuate in shape and have a tongue  18  at one end and a cut-out  20  at the opposite end. The cut-out  20  defines a pair of lugs  22 . The lugs  22  are provided with an aligned bore  24  and the tongue  28  has a bore  26 . 
         [0070]    Each of the casing segments  16   a  to  16   c  is provided with a hole  28  which forms part of a hub opening  30  (best shown in  FIG. 2 ). 
         [0071]    The remainder of the opening  30  is defined by a hub ring  32  so that the peripheral edge of the hole  28  and the inner peripheral edge of the ring  32  form the opening  30 . 
         [0072]    Each propeller blade  34  has a base defined by a stem  36  and a base ring  38  which locates on the stem  36 . 
         [0073]    As best seen in  FIGS. 2 and 3 , hub ring  32  has an inclined hub surface  40  which tapers inwardly from a radially outermost edge to a radially innermost edge. The base ring  38  is provided with an inclined base surface  42  which tapers inwardly from an outermost edge to an innermost edge and which engages with the base surface  40 . Thus, the surface  40  and  42  are conical in shape. 
         [0074]    The base ring  38  is provided with an outer cylindrical section  44  which engages the stem  36  and an inner right angle shoulder  48 , which are best seen in  FIGS. 2 and 3 . 
         [0075]    A slide ring  51  locates in the shoulder  48  and about the stem  36 . 
         [0076]    Each stem  36  is provided with a bore  52  and an eccentric shaft  54  passes through the bore  36 . The eccentricity of the shaft  54  is defined by cut-out or flattened sections  56  on the shaft  54  which receive surfaces  57  defined by cut-outs  59  (only one set shown in  FIG. 1 ) of the slide ring  51 . The hub ring  32  has arcuate cut-outs  33  which locate over the eccentric shaft  54 . In  FIG. 1 , four arcuate cut-outs are shown to make it easier to locate the eccentric shaft on an aligned pair of the cut-outs. However, only two of the cut-outs are needed in order for the hub ring  32  to sit on the eccentric shaft  54 . The shaft  54  is also provided with an elongate central hole  58  and the end of the stem  36  is provided with a bore  62  (see  FIG. 2 ) so that a pin  64  can pass through the hole  58  and into the bore  62 . 
         [0077]    The stem  36  is journaled in a bushing or bearing  68  and a spring washer  70 , such as a Bellville washer, elastic or plastic ring, is located at the end of the stem  36  for biasing the stem  36  radially outwardly. The Bellville washer  70  sits against a central support section  80  (see  FIG. 1 ) of the hub between the hub ends  12  and  14 . 
         [0078]    Each of the eccentric shafts  54  has a pin  90  which locates in a bore  92 . The pin  90  locates in an eye  93  rotatably supported in outer ring  94  of finger  95 . The finger  95  is formed from a finger base part  95   a , an end part  95   b  which carries the ring  94  and a screw  95   c  which locates through the base part  95   a  and screws into the part  95   b  to join the parts  95   a  and  95   b  together. Each finger has a bifurcated portion  97  having aligned openings  98  which receive a pivot pin  99 . A claw  100  having three arms  101  is provided, each of the arms  101  has a hole  102  for receiving the pin  99  so as to pivotally connect the fingers  95  to the respective arm  101 . 
         [0079]    A bush  103  locates in central opening  104  of the claw  100  and receives the end of the push rod  50  for connecting the push rod  50  to the claw  100  and preventing the push rod from passing all the way through the claw  100  and to limit the travel of the pushrod in a drive shaft (not shown). Washers  115  locate in hub end pieces  12  and  14  to also support the drive shaft (not shown). 
         [0080]    In order to form the hub casing, the segments  16   a  to  16   c  locate between the ends  12  and  14  with the tongue  18  of one segment locating in the cut-out  20  of an adjacent segment. Pins  106  pass through holes  108  in the hub end  14  and through aligned bores  24 , as well as the bore  26  of the tongue  18  which locates in the respective cut-out  20  to join the segments  16   a  and  16   c  together and also couple them to the end  14 . The pins  106  located in bores (not shown) in the other hub end  12  and a hub exhaust outlet end  110  screws onto the end  14  to lock the pins  106  in place and prevent them from being retracted. 
         [0081]    In order to adjust the pitch of the propeller blade  34 , the push rod  50  moves either to the right or left in  FIG. 1  to in turn move the claw  100 . Movement of the claw  100  moves the fingers  95 . The longitudinal movement of the fingers  95  will tilt the pin  90  into or out of the plane of the paper in  FIG. 2  and therefore rotate the shaft  54  about the longitudinal axis D of the shaft  54 . The amount of rotation of the shaft about the longitudinal axis D is limited by the movement of the pin  64  relative to the arcuate slot  58  through the shaft  54 . Rotation of the shaft  54  will pull the stem  36  radially inwardly allowing the ring  32  move radially inwardly so that load between the surfaces  42  and  40  is removed. Continued movement of the fingers  95  will then rotate the stem  36  about the axis Y in  FIG. 1  to thereby rotate the blade  34  and adjust the pitch of the blade  34 . 
         [0082]    The rotation of the eccentric shaft  54  pulls the stem  36  radially inwardly very slightly and in the order of about 1/10 of a millimetre. This movement removes the load from the surfaces  40  and  42  and transfers the load to the load carrying surface  61  of shoulder  48  and load surface  63  on the sliding ring  51  which run on a slightly smaller radius than the surfaces  40  and  42 . The movement of the surfaces  40  and  42  relative to one another during adjustment of the pitch of the propeller blade  34  is a sliding movement on one another with very little, if any, spacing between the surfaces. This is advantageous because it prevents sand and other small particles from entering the mechanism between the surfaces  40  and  42 . 
         [0083]    When adjustment has been completed, centrifugal forced acting on the propeller blade  34  tends to push the blade  34  outwardly so that the eccentric shaft  54  and pin  90  can move slightly, allowing the load to be retransferred to the surfaces  40  and  42  to lock the propeller blade in the pitch adjusted position. The spring  70  may facilitate some of the return movement of the eccentric shaft  54  and pin  90 . 
         [0084]    Since modifications within the spirit and scope of the invention may readily be effected by persons skilled within the art, it is to be understood that this invention is not limited to the particular embodiment described by way of example hereinabove. 
         [0085]    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.