US2243095A - Variable pitch propeller control - Google Patents

Description

M y 1941- J. H. HAMMOND, JR., ET AL 2,243,095

VARIABLE PITCH PROPELLER CONTROL Filed Sept. 29, 1938 INVENTOR JOHN HAYS HAMMOND,JR.

/ORNEY BY GEORGE A. COLLEY.

Patented May 27, 1941 UNITED STATES PATENT OFFICE VARIABLE PITCH PROPELLER CONTROL John Hays Hammond, Jr., Gloucester, and George A. Colley, Newton Center, Mass.; said Colley assignor to said Hammond Application September 29, 1938, Serial No. 232,324

3 Claims.

This invention relates to variable pitch propellers andmore specifically to means for automatically varying the pitch ofa propeller so as to maintain the speed of a vessel constant under varying conditions of wind and weather.

The invention further relates to speed indicating means operated by the motion 01' the vessel through the water which directly controls means for varying the pitch of the propeller blades in such a way that the power supplied to the propeller is varied so as to maintain the vessel at a predetermined speed.

The invention also provides means for vary! ing the rate of change of pitch of the propeller blades in accordance with the rate of change of the vessel's speed, thu preventing rapid changes of pitch of the propeller blades which might cause unnecessary strain and vibration on the driving machinery.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed.

Although the novel features which are believed to be characteristic of this invention will be particularly pointed out in the claimsappended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization, may be better understood by referring to the following description, taken in connection with the accompanying drawing forming a part thereof, in which the single figure illustrates diagrammatically the system as applied to the driving mechanism of a marine vessel.

In the following description and in the claims parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Referring to the accompanying drawing, the hull of a marinevessel is indicated at II. This vessel is driven by means of a propeller I2 which is provided with adjustable blades l3. The propeller I2 is attached to the end of a hollow shaft l5 which passes through an outboard bearing l6 and a thrust bearing 11. The shaft I5 is driven by a prime mover 20 which may be of any desired type and is preferably provided with a governor, nor shown, for maintaining a constant speed of rotation.

The blades l3 are connected to a variable pitch mechanism l8 which may be.-of any well known and standard construction such as that manufactured by the Escher-Wyss Company of Zurich, Switzerland, the details of which form no part of the present invention and are accordingly not specifically set forth herein. This a worm 22 which operates to move theupper end of a floating lever 23, which, in turn, is pivoted to the end of a valve rod 24 which controls the valve 25. The piston 2! is connected by a rod 28 to a collar 29 which is slidably mounted on the shaft l5 and engages the lower end of the lever 23 so that the position of this end of the lever corresponds to the pitch of the blades l3.

The upper end of the lever 23 is connected by a wire 30 to an indicator 3| which shows the pitch at which the blades l3 are set. Stops 32 are provided for limiting the maximum and minimum pitch of the blades l3. The fluid pump 26 is driven either by a motor 33 or a belt 35 from the shaft IS. A reservoir 36 and a supply tank 31 are provided for the necessary fluid.

It is to be understood that other pitch control devices may be employed in place of that referred to above, for varying the pitch of the propeller blades I3 in response to actuation of the motor 2|. A particular type is shown for purposes of illustration only.

Mounted on the hull H is a speed indicating device which may be of any well known and standard construction such as that made by the Kenyon Instrument Company of Boston and known as the Kenyon Speedometer. This comprises a strut 40 which is attached to a metallic bellows 4| containing fluid under pressure. The

' bellows 4| is connected by a hydraulic tube 42 to a speedometer 43, which is provided with a pointer 44 which registers with a scale 46 graduated in knots. It is to be understood that other types of speed indicating devices may be used if desired.

In accordance with the present "invention means is provided to control the motor 2| in response to the position of the pointer 44. In the embodiment shown a contact 46 is attached to but insulated from the pointer 44. Surrounding the speedometer 43 and rotatably mounted thereon is a ring 4! to which is attached a segment of a worm gear 48. Meshing with the gear 48 is a worm 49 which is rotated by means of a knurled knob 56. Mounted on but insulated from the ring 41 are a plurality of contact segments 5| to 56 which are selectively engaged by the contact 46.

The segments 5| and 56 are connected by flexible conductors to two conductors 60 and 6| which in turn are connected to reversing windings of the motor 2|. The segments 52 and 53 are connected by flexible conductors to two resistors 66 and 61 the other ends of which are connected to the conductor 60. The segments 54 and 55 are connected by flexible conductors to two resistors 10 and II the other sides of which are connected. to the conductor 6|. The common lead of the reversing windings of the motor 2| is connected to one side of a battery I2 the other side of which is connected to the blade of a three position switch 13. The center contact of this switch is connected to the contact 46, the upper contact to the conductor 6| and thelower contact to, the conductor 60.

Operation In the operation of the form of the invention shown the pitch of the blades I3 is set at the normal operating angle for the speed at which it is desired to operate the vessel, which for example may be 20 knots. The setting of the propeller blades I3 is accomplished by moving the blade of the switch 13 into the upper or lower position which will cause the motor 2| to move the upper end of the lever 23 to the left or right to increase or decrease the pitch in a well known manner, the angle of pitch being indicated by the pointer of the indicator- The vessel is then brought up to the desired speed as indicated by the pointer 44, in this case 20 knots. The ring 41 is then rotated by means of the knurled knob 50 until the insulation between the segments 53 and 54 engages the contact 46. The blade of the switch 13 is then moved into engagement with the center contact.

If :the conditions under which the vessel is travelling should change such as encountering a strong head wind or running into a heavy sea and the speed of the vessel be thereby diminished, the strut will receive less pressure so that the hydraulic cylinder 4| will transmit less pressure to the speedometer 43, the pointer 44 of which will therefore rotate in a counter clockwise direction to indicate a decrease of speed. The contact 46 will then engage the segment 54 and a circuit will be closed from the battery 12 through the resistor I0 to the motor 2| causing it to rotate slowly in a direction to move the upper end of the lever 23 to the left, for example. This will move the valve 24 to the left, which will allow fluid under pressure to pass from the pump 26 to the cylinder 210. by means of the ducts in the shaft l5. This will actuate the piston 21 which, by means of the rodv I9 and the link mechanism, will cause the propeller blades |3 to slowly increase their pitch. This will cause more power to be transmitted from the prime mover 26, the R. P. M. being maintained constant by means of the'governor, thereby increasing the speed of the vessel until it reaches 20 knots, at which time the contact 46 will again rest on the insulation between segments 53 and 54, thus stopping the motor 2|.

If the vessel should increase its speed due to a following wind or other favorable conditions the reverse action would take place, thus causing a. gradual decrease in pitch of the propellers which would cause less power to be drawn from the prime mover 20, thus decreasing'the speed until the contact 46 again rested on the insulation between the segments 53 and 54 at which time the motor 2| would stop.

If the changed conditions cause a rapid change of speed so that the contact 46 engages either segment 55 or 52 then resistor 1| or the resistor 66 will be thrown in circuit with the motor 2|. As resistors and 66 have less resistance than resistors 10 and 61 the motor 2| will be caused to rotate faster, thus changing the propeller pitch more rapidly to take care of the more rapidly changing conditions.

If the conditions change so quickly that the contact 46 engages either segment 5| or segment 56, then no resistance will be thrown in the circuit of the motor 2| and it will rotate at its maximum speed, thus changing the propeller pitch at a maximum rate. The stops 32 are provided so that the propeller pitch is prevented from exceeding certain limits beyond which it could not operate efllciently under any conditions. v

In this way the pitch of the propeller blades I3 is varied to cause the propeller to operate so as to draw the required power from the prime mover 26 under the changed conditions to maintain the speed of the vessel constant. The rate of change of pitch will vary in accordance with the change of speed of the vessel so that with a gradual change of speed there will be a slow change of propeller pitch, thus preventing violent changes of pitch which would cause undue strain on the driving mechanism, disagreeable vibrations and inefliciency oi the propeller.

Although only a few of the various forms in which this invention may be embodied have been shown herein, it is to be understood that the invention is not limited to any specific construction but maybe embodied in various forms without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. In a system for driving a vessel, a propeller having blades, means controlling the pitch of said blades, means responsive to the speed of travel of said vessel, a device actuated by said speed responsive means, said device being provided with a plurality of contacts which are adapted to be selectively closed in accordance with the direction and the amount of change in speed and control circuits associated with said contacts to actuate said pitch controlling means in a direction determined by the direction of change of said speed responsive means and at a rate determined by the amount of such change'whereby the pitch is varied in a manner to maintain the vessel at a constant speed.

2. In a system ,for driving a vessel, a propeller having blades, means controlling the pitch of said blades, means of shiftable position responsive to the speed of travel of said vessel, means responsive to the direction of change of said speed responsive means connected to actuate said pitch changing means in a direction and by an amount to make a change in the pitch of said blades suitable for maintaining the speed of travel of said vessel constant, and means responsive to the amount oi. change of position of said speed responsive means in either direction to cause said pitch-changing means to operate at a rate of speed which varies according to said amount of change, being greater when the amount of said change is greater and vice versa, whereb the rate 01' change of pitch of the propeller blades depends upon the amount of variation in speed of travel of said vessel.

3. In a system for driving a vessel, a propeller having blades, means controlling the pitch of said blades including an electric pitch-changing motor, means of shiftable position responsive to the speed of travel of said vemel, means responsive to the direction of change of said speed responsive means connected to actuate said pitch changing motor in a direction and by an amount to make a change in the pitch of said blades suitable for maintaining the speed of travel of said vessel constant, and means responsive to the amount of change of position of said speed responsive means to cause said pitch-changing motor to operate at a rate of speed which varies according to said amount of change, being greater when the amount of said change is greater and vice versa, whereby the rate of change of pitch of the propeller blades depends upon the amount of variation in speed of travel of said vessel.

JOHN HAYS HAMMOND, JR.

GEORGE A. COLLEY.

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