Marine propulsion – Screw propeller – Self-clearing
Reexamination Certificate
2000-04-28
2001-06-19
Basinger, Sherman (Department: 3617)
Marine propulsion
Screw propeller
Self-clearing
C440S006000
Reexamination Certificate
active
06247980
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to a trolling motor which includes a propeller, motor housing, and support column cleaning function. More specifically, it relates to a trolling motor which includes a motor control system which is capable of executing a predetermined sequence of events which will loosen or clear entangled weeds from the propeller, motor housing, and support column.
2. Background
Trolling motors are waterproof electric motors, typically under two horsepower which are fitted with a propeller and used to control the movement and position of fishing boats. Operation of trolling motors in weed infested waters has long been recognized as a problem. Weeds become entangled on the support column, the motor housing and the propeller, thereby causing a dramatic reduction in performance, even to the point where propulsion of the boat becomes impossible. Typically when weed fouling occurs, the user first attempts to remove the weeds by manipulating the controls of the trolling motor. This might involve increasing the speed to full speed and steering the trolling motor in a different direction. When this method fails, the user must pull the trolling motor out of the water and remove the weeds by hand. This, however, is not a satisfactory situation since during the time the trolling motor is out of the water, the boat is free to drift, often times moving further into weed infested areas and making the situation worse. Furthermore, if the trolling motor is not equipped with an automatic shut-off which operates to disable the motor when it is out of the water, hand cleaning could present a potential safety problem. Over time, numerous techniques have been developed to deal with weed entanglement but none of these techniques has proven satisfactory for all operating environments.
For example, devices have been developed which attach to the motor housing and support column which are intended to deflect weeds away from the propeller. Unfortunately, these devices create drag which hampers the effectiveness of the trolling motor even when not in weed infested areas, they provide no protection for the support column or motor housing, and they do not completely eliminate entanglement of the propeller. In fact, these devices themselves can collect weeds, thereby adding additional drag and making the trolling motor difficult, or impossible, to steer.
A second approach has been to utilize specially designed propellers, commonly called weedless propellers. These propellers are shaped such that they reduce weed gathering and shed, rather than collect, weeds. However, the performance of these propellers, in regards to their ability to self clean, changes with propeller speed. Fouling of the propeller, support column, and motor housing is much more likely to occur at low speed operation than at high speed. Additionally, these propellers do not reduce weed fouling of the support column and motor housing, which causes further drag and reduces the effectiveness of the trolling motor.
It has been recognized that momentarily reversing the direction of rotation of the motor can cause entangled weeds to disengage from the propeller. However, most trolling motors which utilize a foot pedal control do not provide any means for reversing the motor. Even with trolling motors which have a means for reversing rotation, the user must manually activate reversal of the motor, thereby disturbing the present speed setting, and thereafter must manually reset the motor to the previous forward speed.
It is thus an object of the present invention to provide a reliable means for cleaning weeds from the propeller, support column, and motor housing of a trolling motor without adversely affecting the operation of the trolling motor.
It is a further object of this invention to provide the trolling motor operator with a means for manually activating a cleaning cycle or periodically activating cleaning cycles without disturbing the preselected forward speed setting of the trolling motor.
It is still a further object of this invention to provide detection of weed fouling of submerged elements of the trolling motor and to automatically activate a cleaning cycle when appropriate.
SUMMARY OF THE INVENTION
These and other objects are achieved in a trolling motor incorporating a motor and electronic control system such that the combination provides a means for momentarily reversing the direction of rotation of the propeller, either automatically or manually, without disturbing the speed set by the operator. The preferred electronic control system includes an input for receiving an user adjustable motor speed and at least one output capable of motivating the propeller to selectively spin in either direction.
In accordance with one aspect of the invention, there is disclosed a trolling motor control system including an input whereby the operator can manually cause the trolling motor to momentarily reverse the direction of rotation of its propeller at a particular speed and thereafter to return to the user selected speed.
In accordance with another aspect of the invention, there is disclosed a control system including at least one timer which produces a periodic signal to automatically activate a cleaning cycle whereupon the propeller is induced to momentarily reverse its direction of rotation at a particular speed for a particular period of time and to thereafter return to the user selected speed.
In accordance with another aspect of the present invention, there is provided a system for automatically sensing when the propeller has become fouled and thereafter initiating a cleaning cycle. In the preferred embodiment, a comparator receives a signal representative of motor performance and, if the performance differs significantly from a threshold level, the comparator initiates a cleaning cycle, wherein the motor is directed to reverse momentarily and thereafter directed to rotate again in the original direction. It is critical for purposes of the instant embodiment that when the motor is directed to rotate again in the original direction it additionally be instructed to return to approximately the same velocity that had been specified by the operator prior to the detection of a fouling condition.
In one preferred automatic cleaning embodiment, the signal representative of motor performance is a tachometer signal which might be provided by a separate tachometer or, alternatively, a tachometer means integral to the control system. In either case, the control system will be able to sense the rotational speed of the propeller, which speed is indicative of weed fouling.
In another preferred automatic cleaning embodiment, the motor performance signal is provided by an electrical current sensing circuit which monitors the current drawn by the motor. When the current exceeds some threshold value for a given selected propeller speed, fouling is indicated.
A better understanding of the present invention, its several aspects, and its objects and advantages will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the attached drawings, wherein there is shown and described the preferred embodiment of the invention, simply by way of illustration of the best mode contemplated for carrying out the invention.
REFERENCES:
patent: 4099478 (1978-07-01), Alexander, Jr.
patent: 4902255 (1990-02-01), Faunda
Henderson William A.
Moore Prentice G.
Welch David W.
Basinger Sherman
Brunswick Corporation
Fellers Snider Blankenship Bailey & Tippens, P.C.
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