Fluid reaction surfaces (i.e. – impellers) – Having frangible or fusible part or connection
Reexamination Certificate
2000-02-29
2001-11-06
Verdier, Christopher (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Having frangible or fusible part or connection
C416S061000, C416S09300R, C416S13200B, C416S153000, C416S205000, C416S208000, C416S240000, C416S207000
Reexamination Certificate
active
06312223
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a marine propeller. The adjustable blades of propellers according to the present invention enable the propeller to be adapted to different running conditions and different types of engines or motors. One advantage with such propellers is that they cover a wider area of use than fixed blade propellers. This enables propeller manufacturers and suppliers to satisfy the requirements of different users with a relatively limited number of types of propeller in the general assortment.
BACKGROUND OF THE INVENTION
Adjustable blade propellers have long been known. These propellers can be divided into two main types, one type with which each blade can be adjusted individually, and another type with which all blades are adjusted commonly in one single movement. One advantage with the latter type of propeller is that it eliminates the need to bring the individual setting of a blade into agreement with the settings of the remaining blades, which can be difficult to achieve and which may result in differences in blade settings.
The inventive propeller lies within this latter type of propeller, i.e. a propeller with which the propeller blades can be adjusted in unison.
Adjustable blade propellers of this kind are described and illustrated in U.S. Pat. Nos. 813,074, 2,574,951, 5,232,345, 2,953,208, 3,403,735, 3,308,889, for instance. A common feature of the propeller constructions described in these publications is that common or unison adjustment of the blades is made to a completely optional setting within the limits given, i.e. the blades can be adjusted to different settings smoothly and continuously. The blades are locked in their new settings, subsequent to this adjustment. This procedure has several drawbacks. Firstly, it is necessary to be able to read or determine the blade setting, so as to establish whether or not the blade has been adjusted to the angle intended. There is also the risk of deviation between the blade setting intended and the blade setting achieved. Furthermore, it is necessary to rely upon force-bound locking of the blades when practicing this continuous blade adjustment principle. This force-bound locking of the blades can result in a change in the blade setting, or may require the application of locking forces of such great magnitude as to cause dismantling and fitting operations in respect of the adjustment more difficult to achieve and induce higher tensions in the material. There is also the risk of a heavily tightened locking device becoming loose in the passage of time, due to vibration and other forces, so as to disturb the blade settings. As a result, a number of the earlier constructions have become highly complicated.
EP 0 300 252 teaches a blade adjuster with which the blades can be adjusted to distinct settings in unison. The arrangement is, however, relatively complicated and involves the conversion of a torsional adjustment movement to an axial adjustment movement of a rod that extends to each propeller blade, through the medium of nuts and spindles. The axial movement of the rod is then converted to rotational movement of respective blades through the medium of a pin carried by the rod and co-acting with a guide groove or channel in the blade root.
SUMMARY OF THE INVENTION
Against this background, it is an object of the invention to provide a propeller of the kind concerned with which the aforesaid problems associated with known techniques in this field have been avoided. More specifically, it is an object of the invention to provide a propeller of simple construction with which the blades can be adjusted to unequivocally defined and positively retained settings.
This object has been achieved in accordance with the invention.
Because the common adjustment movement is performed through the medium of relative movement between two elements, the adjuster ring and the hub, which can be shape-locked together in predetermined distinct positions, the blades can be adjusted to defined positions such as to eliminate the risk of accuracy deficiency and such as to obviate the need for measuring a precise position of adjustment or setting. All that is required to show to which of the predetermined positions the adjustment relates is a simple indication index. The shape-bound locking facility also ensures that the blade setting will not be disturbed and affected by vibrations and running disturbances. The inventive propeller is also of simple construction and therewith relatively inexpensive in manufacture.
According to one preferred embodiment of the invention, the means by which the adjustment adjuster ring and the hub are locked relative to one another in their circumferential direction are disposed on the mutually facing surfaces of said adjuster ring and said hub.
The locking elements suitably have the form of axially extending teeth with intermediate grooves or channels on each of the two surfaces.
The grooves and teeth have a complementary shape, so as to engage with one another in locking the adjuster ring and the hub together. One of said surfaces will include a plurality of teeth and the other at least one tooth, preferably several teeth. The teeth and the grooves ensure that the shape-bound locking effect is achieved and also define the blade settings.
According to another preferred embodiment, the movement transmission element that transmits rotation of the setting adjuster ring to the propeller blades is comprised of a plurality of arms, each of which is connected at one end to the root of a blade and the other end of which projects into a respective recess provided in the blade setting adjuster ring. This provides simple and reliable transmission of rotation of the adjuster ring to rotation of the propeller blades.
As a result of this simple construction of the blade adjusting mechanism, space can be provided for accommodating exhaust passages in the hub. A preferred embodiment of the invention thus includes such an arrangement of exhaust passages. This facility provided by said construction is particularly beneficial in view of the fact that the propeller is intended for use with several different types of drive motors.
According to one particularly beneficial embodiment of an inventive propeller, the blades are flexible so that their propelling behaviour will be influenced by operating or running conditions, which is of particular importance when the propeller blades can be adjusted in distinct steps. A preferred embodiment of the invention also relates to this facility.
According to another preferred embodiment, each blade has a weakened part that forms a fracture location. This prevents the hub from being damaged in the event of the propeller blades striking against a stone or some other object. This is of particular importance in respect of an inventive propeller, since a hub that is constructed for stepwise adjustment of the blade settings is more sensitive to external forces than a hub to which the blades are fixedly connected.
The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:
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Burns Doane Swecker & Mathis L.L.P.
Verdier Christopher
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