US 2307040 A
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Description (OCR text may contain errors)
Jam 5, 1943 J. H. HAMMOND, .JR 2,307,040
VARIABLE FITCH PROPELLER CONTROL Filed April 17, 1941 2 Sheets-Sheet 1 INVENTOR JOHN HAYS HAMMOND, JR. BY
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J. H. HAMMOND, .JR VARIABLE FITCH PROPLLER CONTROL Filed April 17, -1941 Jan. 5, 1943.
t INVENToR l.JoHN HAYs HAMMoND.JR.
Patented Jan. 5, 1943 'UNITI-:Dl STATESPATENT ori-*lcs 1;
VARIABLE PITQH PROPELLER CONTROL John Hays Hammond, Jr., Gloucester, Mass.
Application April 17, 1941, Serial No. 388,9#
3 Claims. Cl. 17o- 163) This invention relates to variable pitch propellers and more specifically to means for automatically varying the pitch ofa propeller in accordance with changes in the speed of the vessel so as to maintain the most eflicient propulsion Although the novel features which are believedl to be characteristic of this invention will be particularly pointed out in the claims appended 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 vconnection with the accompanying drawings forming a. part thereof, in which Figure 1 illustrates diagrammatically the automatic recording system as applied to a marine vessel, and
lFigure 2 illustrates diagrammatically the system as applied to the control oi.' the pitch of the propeller blades in accordance with the speed of the vessel;
Like reference characters denote like parts in the several figures of the drawings.
In the following description and in the claims parts will be identied by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.v
Referring more particularly to Figure 1, the hull of a marine vessel is indicated at Il. The vessel'is driven by means of a propeller I2, which is provided with adjustable blades I3 and which has an outboard bearing in a rudder post I4. The propeller I2 is attached to the end of av hollow shaft I5 which passes thru a bearing I6. A rudder I1 is mounted on the rudder post I4.- The shaft I5 is driven by a prime mover which may be of any desired type and is preferably provided with. a governor, not shown, for maintaining acon- .A
stant speed of rotation.
mechanism I8 which may be' of any well known andy standard construction such as that manufactured by the Escher-Wyss Company of Zurich, Switzerland, the details 'o'f which form no part of the present invention and are accordingly not specifically set forth hereine 'This mechanism, in general, comprises a rod I9 slidable longitudinally within the shaft I5 and connected to control the pitch of the blades I3. The rod IS's actuated by a piston 21 in a iiuid pressure cylinder 21a. Fluid for actuating the piston' 21 is supplied by a pump 26 through a control valve 25 and a distribution valve a.which communicates with the cylinder 21a through ducts, not shown, in the shaft I5.
A motor 2l rotates a worm 22 which operates to move the upper end of aiioating lever 23. which, in turn, is pivoted to the end of a valve rod 24 which controls the valve 25. The piston 21 is connected by a rod 2B to a collar 23 which is slidably mounted on the shaft I5 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 n.
Stops 32 are provided for limiting the maximum and minimum pitch ofthe blades I3. The
fluid pump 251s driven either by a motor 33 or a belt 35 from the shaft I5. A reservoir 36 and a supply tank 31 are provided for the necessary fiuid. The motor 2| is provided with two windings for causing it to rotate in opposite These windings are connected to the two poles of a double throw switch 33; the blade of which is connected thru a battery 33 tothe common return to the motor 2|.
It is to be understood that other pitch control devices may be employed in place of that referred to above, for varying the pitch ofthe propeller blades I3 in response to actuation of the to the accompamring drawings and 'y motor 2l. A particular type is shown for purposes of illustration only.
lA recording. mechanism 40 is provided which contains a moving strip of paper 4I which is caused to move upward at a uniform rate by any well known means and upon which three records 42, 43 and 44 are'made by three styluses 45, 45 and 41 which are mounted on the ends of the pointersof lthree indicators 43, 45 and 50.1
The indicator ll is 0f the mechanical type and is connected by a wire 5I to the upper end of the lever 23 and indicates the pitch at which the blades I3 are set. The indicators 4 9 and 5l are The blades I3 are connected to a variable pitch. 55
of the electrical type and are electrically connected'to two generators 52 and 53 which are driven by two Propellersl and 56. the former to the conductor 1 I.
being located in the slip-stream of the propeller I2 and the latter being located below the hull II. These devices for measuring the velocity of the water are of well known and standard construction and need not be more fully described herein and operate in such a way as to cause the pointers of the indicators 49 and 58 to move an amount proportional to the velocity of the water in which the propellers 55 and 56 are located.
Operation In the operation of the recording system shown in Figure 1 the vessel is taken o ut for trial trips under various conditions of wind and weather and the power delivered by the prime mover 20 is kept substantially constant by means of the governor. Some of the runs are made against the wind, some are made across wind when its effect is negligible and others are made with the wind.
In each run after the vessel is on its course and conditions have become stabilized the pitch of the blades I3 is varied'by operating the switch 3B until the maximum speed under the given conditions has been obtained as indicated by the pointer of the indicator 5U. The setting of the blades I3 is accomplished by moving the blade of the switch 38 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 pitchI in a well known manner, the angle of pitch being indicatedby the pointer of the indicator 48.
After a set of runs under various conditions.
of wind and weather has been made a series of curves 42, 43 and 44 are obtained giving the maximum speed obtainable under each particular condition of wind and weather with constant power output and also the optimum blade angle under each set of conditions. 'Ihe'data from these curves will be used in the construction of a cam tojbe described in connection with Figure 2.-,
In Figure 2'is shown the mechanism for con-l trolling the pitch ofthe blades I3 in accordance with the speed of the 'vessel under various conditi'ons of wind andweather and with constant poweroutput. The mechanism shown in this gure vissimilar to that shown inlFigure 1 up to and including the battery 39, the corresponding parts, being given the same numbers. In this gure,.however, the recorder 40 has been replaced by a pitch control mechanism 60 and the generator 52 and propeller 55 have been eliminated.
The pitch control mechanism 60 comprises a base 6I upon which are mounted the indicator 58, 'which is connected to the lever 23 by the wire 5I and the indicator 50, which is connected to the generator'V 53 and the propeller 56. Rotat- .ably mounted over the indicator I8 is a. segmental member 62. Mounted on but insulated from this member are six contact segments 63-68 which cooperate with a contact 1u attached to the end of the pointer of the indicator 48. The contact 10 is connected to one side of the battery 39.
The segments 63 and 68v are connected to two conductors 1I and 12 which are connected to the reversing windings of the motor 2|. The segments 64 and 65 are connected to two resistors 13 and 14 the other ends of which are connected The segments 66 and 61 are connected to two resistors 15 and 16 the other ends of which are connected to the conductor 12.
. of a. worm wheel 19. Meshing with the worm wheel segment 19 is a worm 89 which is secured to the shaft of a motor 8| which is mounted on the base 6I. Attached to the pointer of the indicator 58 is a contact 82 which cooperates with two contact segments 83 and 84 which are mounted on but insulated from the member 18. The contact segments 83 and 84 are connected to the reversing windings of the motor 8|.v 'I'he common return of the motor 8| is connected to one side of a battery 85, the other side of which is connected to the contact 82.
The member 18 is connected by a link 86 to a cam 81 which is pivotally mounted at 88 to the base 6I. The faceof the cam 81 is engaged by a roller mounted on an arm 9| which is pivotally mounted at 92 to the base 6I. A spring 93 tends to hold the lroller 90 in engagement with the face of the cam 81. A link connects the arm 9| to the lower end of the segmental member 62.
Operation lower position which will cause .the motor 2| to move the upper end of the lever 28 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 48.
'I'he vessel is then brought up to the desired speed at which time the generator 53 will produce a certain voltage, due to the rotation of the propeller 56, which will be transmitted tothe indicator 50, the contact 82 of which will take up a position corresponding to the speed of the vessel. As the contact 82 rotates it will engage one or the other of the segments`83 or 84 causing an electrical circuit to be closed from the battery 85 thru the motor 8| which will cause this motor to be rotated in such a direction that the insulation between the contact segments 83 and 84 will follow the motion of the contact 82.
This motion is transmitted by the link 86 to the cam 81 which will thus take up a position corresponding to the speed of the vessel. As the cam 81 is rotated it will cause a rotation of the arm 9| which by means of the link 95 will cause the segmental member 62 to be rotated an amount determined by the speed of the vessel and the shape of the cam 81. As `the member 62 rotates it wili cause either contact segment 65 or 66 to cngage the contact 10 causing an electrical circuit to be closed from the battery 39 thru either. resistor 14 or resistor 15 and the motor 2|, which will cause this motor to be slowly rotated in such a direction that the lever 23 will, acting thru the wire 5Iand indicator 48, cause the contact 10 to follow the motion of the insulation between the contacts 65 and 66.
The motion of the lever 23 will operate the valve 25 which will allow fluid under pressure to pass from the pump 26 to the cylinder 21a by means of the ducts in the shaft I5. This will actuate the piston 21 which, by means of the rod I9 and the link mechanism,..wil1 cause the propeller blades I3 to slowly change their pitch. In this way the pitch of the blades I3 is`caused to follow the motion of the mem'ber 62,- which, as
asoaoaoA previously stated, is determined by the speed of the vessel and the shape of the cam 81.
If the speed of the vessel should change more rapidly so that either segment 64 or 61 engage the contact then either resistor 13 or 16 will be thrown in the circuit with the motor 2l. As resistors 13 and 16 have less resistance'than resistors 14 and 15 the motor 2| will be caused to rotatefaster, thus changing the propeller pitch more rapidly to take care of the more rapidly changing conditions. If the conditions change so quickly that either segment 63 or 68 engages contact 10 then no resistance will be thrown in the circuit of the motor 2i and it Will rotate atA its maximum speed, lthus 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 eiciently under any conditions In this way the pitch of the propeller blades I3 is varied in accordance with the speed of the vessel and the shape of the cam 81. The shape of this cam isdetermined from the graphs on the paper strip il (Figure 1). As already stated these curves show the most emcient propeller blade angle, curve d2, to Vgive the maximum ship speed. curve 44, with constant power output under various conditions of wind and weather. Thus for each possible ships speed taken from curve 44 the corresponding propeller blade angle is obtained from curve 4| and the radius of the cam 81 for each point is thereby determined. It is thus seen that in this way the propeller blades I3 are always set at the optimum angle for the conditions under which the ship is operating at that time. f
The recording mechanism shown in Figure l may also be used for determining the optimum relation between the ships speed and the propeller slip-stream speed which would be necessary is constructing the cam shown in my co-pending application, Serial No. 388,943. This relationship is obtained from the curves M and I3.
Although only a few oi' 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 specic construction but might be embodied in various forms without departing from the`spirit of the invention or the scope of the appended claims.
What is claimed is:
l. In a system for driving a vessel, a variable pitch propeller having blades, speed indicating means directly responsive to the speed of the vessel, pitch control means to control the pitch of said blades, and a follow-up system interconnecting said speed indicating means and said pitch control means, said follow-up system including a non-linear response element designed in accordance with pre-calculated characteristics selected in accordance with the optimum pitch angle for various vessel speeds and arranged to control the pitchof said blades in accordance with said pre-calculated characteristics. s
2. In a system for driving a vessel, a variable pitch propeller having blades,'.speed indicating means directly responsive to the speed of the vessel, pitch control means to control the pitch of said blades and a follow-up mechanism actuated by said speed indicating means, a cam member actuated by said follow-up mechanism-and having pre-selected characteristics suited to obtain the desired operating relationship between the vessels speed and the propeller pitch, a
second follow-up mechanism actuated by said cam member, and means controlled by said second follow-up mechanism to actuate said pitch control means, whereby the pitch of said blades is varied as a function of the speed of the vessel which is dependent upon the shapeof said cam.
3. In a vessel, a variable pitch propeller having blades,v driving means for said vessel, means to vary the pitch of said blades, indicating means actuated by said last means to indicate the blade pitch, means responsive to the speed oi travel ot said vessel, indicating means actuated by said last means, means responsive tothe speed of the propeller slip stream of said vessel, indicating means actuated by said last means, all of said indicating means comprising styluses and a common chartv cooperating with said styluses to produce a record of the relationship between propeller pitch, ship speed and slip stream speed.
JOHN HAYS HAMMOND, Ja.