Safety Cut-off For Propellers

Abstract

A device to impact on an obstruction and stop a propeller before its moving lades can impact thereon. The device has extensions beyond the path of the propeller blades which extensions are attached to micro switches to cut-off power to the propellers.

Description

The invention described herein may be manufactured and used by or for the Government of the United States of America for Governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION

The use of submersibles for research and reconnaisance is finding more widespread use with the development of the Hazelton or tandem propulsion system. The Hazelton system has a propeller at the fore and aft end of the hull with the hub being a large annular ring of the size and contour of the hull. The blades are spaced around the hub and have variable pitch capabilities. The blades can be pitched either collectively or cyclically at points around the circumference. This provides 6.degree. of freedom of motion without the use of a rudder or other auxiliary thrusters. This capability lends itself to maneuvering in close quarters and working in conjunction with divers. While the propellers are relatively slow moving, 30 to 90 RPM, the propellers must be protected against impact damage and the divers against injury.

DESCRIPTION OF THE PRIOR ART

The recent development of the Hazelton propulsion system has precluded any protective devices for such propellers. The only possible protection means would be to adapt the devices used on conventional screw propellers for use with a Hazelton propeller. Since the blades of a Hazelton propeller extend beyond the contour of the hull, around the circumference thereof, the use of skegs, cages or struts would be prohibitive. Such devices would have to be extremely large, with respect to hull diameter, and would consequently produce large drag forces. The size and drag would make them sonically noisy and thereby easily detected. Such arrangements are therefore considered wholly unsuitable.

SUMMARY OF THE INVENTION

Due to the relatively low speeds of the Hazelton propellers they can be readily stopped within a fraction of a revolution as opposed to conventional screw propellers with their relative high speeds. The invention therefore, involves an emergency cut-off utilizing probes or feelers that extend beyond the arc of the path of the propeller. These feelers are attached to micro-switches so that when the feelers strike an object the propeller is stopped. The feelers can be mounted on the hub or on the hull.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a submersible equipped with the subject invention.

FIG. 2 is a partial cross-sectional view of another embodiment of the subject invention.

FIG. 3 is a partial cross-sectional of a further embodiment of the subject invention.

FIG. 4 is an end view of a still further modification of the subject invention installed on a submersible.

FIG. 5 is a side view, with parts in section, for clarity, of the embodiment of FIG. 4.

DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, of the drawing, a Hazelton type propeller 10 is shown installed on a submersible 11. The propeller 10 has an annular hub 12 with a series of controllable pitch blades 14 mounted thereon. In FIG. 2, the blades 14 have an elongated spindle 16 that extends through the hub 12 and is rotatably journalled therein by a pair of bearings 18. A seal 20 acts between the spindle 16 and the hub 12 to prevent leakage thereby. A crank 22 is fixed to the interior end of the spindle 16 to implement the pitch changing function of the propeller. The broad details of the Hazelton type propeller have been set forth hereinabove to illustrate the environment within which the subject invention is to be used. It is understood that this does not form a part of the subject invention and greater detail is not therefore required.

The blade 14 and spindle 16 are provided with an opening 24 that extends therethrough. The opening 24 extends from the interior of the hull to the tip of each blade 14 to carry a feeler or probe 26. The probe 26 has a diameter of sufficiently small diameter, with respect to opening 24, so that there is clearance on all sides thereof. The probe 26 is attached at its inner end to a micro-switch assembly 28. The switch assembly 28 is provided with a resilient boot 36 to seal the entry of the probe thereinto. The length of the probe 26 is such that when it is mounted in position, as shown in FIG. 1, the end thereof protrudes a sufficient distance A, beyond the arc of travel of the blades 14. Due to the rotation of the entire Hazelton assembly, including the subject invention, the micro-switch terminals 40 are positioned for wiping contact.

The operation of the embodiment of FIG. 2 is relatively simple and straightforward. The probe 26 extends well beyond the arc of travel of the blades 14. Therefore, collision with an object, whether a diver or something stationary will occur with the probe 26. The probe, being mounted within the opening 24 with clearance, will rock in its mounting thereby actuating the micro-switch 28. The actuation of the switch can be utilized to shut-off the power to the propeller 10 or sound an alarm or both. As mentioned hereinabove, the low RPM of the Hazelton type propeller will permit stoppage within a fraction of a revolution or before the blades can be damaged by collision or before a diver can be hurt. For the most effective protection, a shut-off assembly is mounted on each blade, while a single installation will provide minimal protection.

Referring, now to FIG. 1, a modification of that shown in FIG. 2, is shown wherein the probe units are mounted between the blades. As shown therein, a probe 32 is attached to a micro-switch assembly 34 with a resilient boot 36 to provide a seal therebetween. The micro-switch assembly 34 is mounted in the hub 12, between blades 14 in a recess 38 with the probe 32 extending outwardly beyond the arc of travel of the blades 14. The terminals 40 of the switch 34 are extended through to the inner surface of the hub 12 to facilitate a wiping type of connection of this embodiment is like that of FIG. 2, in that impact of an object against the probe 32 will move it and actuate the micro-switch 34 thereby stopping the propeller. It should be noted that this embodiment lends itself to being mounted on the hull adjacent the propeller. As in the first embodiment, the greater number of probes used the more complete and certain the protection against collision.

Referring now to FIG. 3, a further embodiment is shown utilizing a weather vane type probe assembly 42. The probe assembly 42 includes a mounting bracket 44 and a pivotal blade 46. The bracket 44 has a resilient bushing 48 mounted in an opening 50 through the hub 12. A sleeve bearing 52 is mounted in the bushing 48 to provide a pivotal mounting for the blade 46.

The blade 46 is arcuate shaped with a shaft 54 mounted at one end thereof. The shaft 54 is mounted in the sleeve bearing 52 and extends therethrough. The end of the shaft 54 that extends into the interior of the hub 12 has a micro-switch assembly 56 mounted thereon to sense any deflection of the shaft 54 in the resilient bushing 48. The blade 46 is of sufficient length to extend beyond the arc of travel of the blades 14, as above.

The operation of the assembly 42 is such that when the propeller is rotating, whether clockwise or counterclockwise, the blade will act as a weather vane and orientate itself to curve away from the direction of rotation thereby reducing drag. This orientation of the blade 46 occurs since the blade is curved and pivoted at one end on the shaft 54. When the blade 46 impacts on an object it will rock within the bushing 48 and activate the micro-switch 56 thereby stopping the propeller before suffering damage or injuring a diver. As above, the greater number of assemblies 42 used on a propeller the more certain the protection. For added convenience, when not desired or deemed unnecessary, the blade 46 and the shaft 54 can be pulled out of the bearing 42, to be reinstalled when needed.

Referring now to FIGS. 4 and 5, a further embodiment of the invention is shown utilizing a circular rail assembly 60. The assembly 60 includes a series of stanchion type probes 62 and an impact ring 64.

The stanchion probes 62 have a micro-switch assembly 66 that is mounted in a recess 68 in the hull of the submersible 11, adjacent the propeller 10. The micro-switch assembly 66 has a probe 70 attached thereinto and extending beyond the arc of travel of the blades 14 as set forth with respect to FIG. 2, above. A series of stanchion probes 62, at least three, are mounted around the circumference of the hull with the impact ring 64 mounted thereon.

In operation, any impact against the ring 64 or a probe 70 will move the probe 70 and actuate the micro-switch 66 which signals therefrom can be used to turn off the propellers.

As is obvious, from the drawings, the assembly 60, lends itself to being used by divers to intentionally stop the propeller. A diver can grasp the ring 64 and rock it to actuate the microswitch. Also, the impact ring assembly 64 could be mounted on probe devices 26 and 32, as shown in FIGS. 1 and 2, respectively, to rotate with the propeller and thereby reduce the number of probe units needed to protect the propeller.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

Claims

What is claimed is:

1. A power cut-off device for submerged propellers of waterborne vehicles, each of the propellers having a rotating hub and blades thereon, the device comprising:

at least one probe having a first end mounted in the rotating hub between any two of the blades;

a second end of each probe extending adjacent the propeller, the second end provided to contact an arc concentric with and of a greater diameter than the arc of travel of the blades when the propellers are driven; and

a switch mechanism operatively connected to each probe whereby impact on the probe will move the probe relative to the switch thereby actuating the switch to stop the propeller.

2. The device of claim 1 wherein the probe has a flat arcuate shaped blade pivotally and resiliently mounted on the rotating hub.

3. The device of claim 1 wherein a plurality of the probes support a ring adjacent the blades.

4. A power cut-off device for submerged propellers of waterborne vehicles, each of the propellers having a rotating hub and blades thereon, the device comprising:

at least one probe having a first end mounted on the vehicle;

a second end of each probe extending through an opening in at least one of the blades, the second end provided to contact an arc concentric with and of a greater diameter than the arc of travel of the blades when the propellers are driven; and

a switch mechanism operatively connected to each probe whereby impact on the probe will move the probe relative to the switch thereby actuating the switch to stop the propeller.