US2682370A - Axis convertee - Google Patents

Description

June 29, 1954 E. E. LIBMAN 2,682,370

AXIS CONVERTER Filed June 5, 1950 2 Sheets-Sheet l mmvron. Earl E. L bmwn,

June 29, 1954 L|BMAN 2,682,370

AXIS CONVERTER Filed June 5, 1950 2 Sheets-Sheet 2 77 cf 1 I 86' 7% w a r a 4 INIfENTOR. fi'azllilzbmauz,

BYW/KM Patented June 29, 1954 UNITED STATES PATENT OFFICE AXIS CONVERTER Earl E. Libman, Brooklyn, N. Y., assignor to Con trol Instrument Company, Ina, Brooklyn, N. Y., a corporation of New York Application June 5, 1950, Serial No. 166,191

10 Claims. 1

This invention relates to improvements in mechanisms employed in positioning guns and has particular reference to an axis converter for use with air-borne guns.

With a gun mounted in the nose structure or turret of a military aircraft, it is frequently necessary, in order to hit a target, to rotate a part of said structure relative to the fore and aft axis of the aircraft and, additionally, to incline the gun to said axis. The rotation about this axis is known as roll and the inclination of the gun is called traverse.

The computer that determines the position the gun should assume in order to hit a target, is ordinarily of the type that computes said position in terms of the spherical coordinates of azimuth and elevation, the former being the angle of rotation of the gun about a vertical axis and the elevation being an angle between the gun and a horizontal plane. When thus computed in terms of azimuth and elevation, it is necessary to convert the gun position data received from the computer into terms of roll and traverse, such step being known as axis conversion. Heretofore, the construction of axis converters often resulted in mechanisms that functioned over only a part of the desired firing area and locked up, mechanically, in other parts of said area, and structural supports or the like also prevented motion of elements of the mechanisms and therefore limited the range of operation thereof.

An object of the present invention is to provide an improved control mechanism of practical construction and positive operation which will convert input data of azimuth and elevation into data of roll and traverse, and wherein. complete freedom of movement of elements of the mechanism within the desired range of operation of the device will be attained.

The above and other objects will appear more clearly from the following detailed description when taken in connection with the accompanying drawings which illustrate a preferred embodiment of the inventive idea; but it will be ex pressly understood that said drawings are employed merely for the purpose of facilitating the description of the invention as a whole and not to define the limits thereof, reference being had to the appended claims for this purpose.

In the drawings:

Fig. l is a diagrammatic view showing the relative positions of the target and the gun, and the spherical coordinates representing the angles of azimuth and elevation;

. positionable elements of the mechanism; and

Fig. 6 is a diagrammatic view of the electrical circuits employed in connection with the mechanism shown inFig. 2.

Referring to Fig. 1, when an aircraft at the point 0 with fore and aft aXis O-O' sights a target, a computer or director predicts the direction 0'? along which gunfire is to be directed and gives this gun direction in spherical coordinates relative to the point 0, as the angles B and E. B is the angle of train O'OPz and E1 is the angle of elevation PzOP', and these represent, respectively, the angle in the horizontal plane through the ships fore and aft axis in which the gun should be trained, and the angle to said horizontal plane throughwhich the gun should be raised or lowered in elevation. Thus, the gun will be directed along the predicted direction OP.

As has been pointed out, some air-borne guns are not free to move in train and elevation but must be directed by motions of traverse and roll. A gun directed so as to possess the train and elevation angles B and E, respectively, has the roll and traverse angles PiOP'and OOP, respectively, so that the gun can be made to assume a desired direction OP either by positioning it by train and elevation angles or by its correspondingroll and traverse angles depending upon the mounting of the gun.

As shown in Fig. 2, the device embodying the features of the present invention comprises a base 8 to which is attached a difierential housing 9 and which supports a standard ill having a laterally extending bracket I l at its upper end. A sleeve 12 extends horizontally from one side of the standard It, and plates 13 and Hi extending similarly from the other side thereof provide a differential housing similar to the housing 9. Said housing 9, the standard I!) and its bracket ll combine to form a support for the moving members of the converter mechanism.

Journaled at IS in the bracket ll and at it in 3 the upper portion of the housing 9 is a hollow arcuate guide member I? of rectangular cross section (Fig. 3) mounted for rotation about a vertical axis, the degree of its rotation being limited only by contact thereof with the bearing sleeve 12 and therefore being considerably in excess of 180. The upper bearing has a stud shaft l8 extending through the bracket II and secured in place by a nut IS. The lower bearing I6 is flanged at 20 to form a support for the member I1, and said bearing is provided at its lower end within the housing 9 with a bevel gear 2| driven by a similar gear 22 on the input shaft 23 so that said member I] may be rotated in train about its axis. The shaft 23 may be connected to a computer or director so as to be rotated thereby and thus convey to the member I! the proper angle of train.

The inner face of the member I? is slotted at Ha substantially throughout its entire length to allow the passage therethrough of a supporting rod 24 carrying at its outer end a soft iron disc 26, with said rod secured at its inner end to the carriage 25 that is capable of movement on its rollers 25a from either end to the other of the member I! thus encompassing a movement of approximately 270. This movement of the carriage 25 is accomplished by means of cables 2'! and 28 (Fig. 5) which have their ends secured to the carriage and which pass over the guiding studs 29 and around the idler pulley 35 and the driving spindle 3|, with said cables wound in opposite directions around said spindle so that as one is wound thereon the other is unwound therefrom to permit the carriage to be moved along its track formed by the inner face of the member I1 and thus be positioned at any point therein. The driving spindle 3| carries the gear 32 meshing with the gear 33 on the shaft 34 journaled in the flange 20, and said shaft is provided with a second gear 35 engaged by a gear 35 on one end of the shaft 31 also journaled in said flange and in the bearing 15 (Fig. 2). At the other end of the shaft 31 within the bearing it, a crown gear 38 meshes with the pinion 39 on the latter shaft, and said gear 38 is carried by a shaft 40 that is driven by the gears 4|, 42, the latter being carried by the input shaft 43 which, like the shaft 23, may also be connected to a computer or director and which is rotated to position the carriage 25 in elevation. When the member [1 and its mounting 20 are rotated by the shaft 23, any tendency of this rotation to impart movement to the carriage 25 by reason of the rolling action of the pinion 39 on the crown gear 38 is counteracted by the unwinding eifect of the differential mechanism supported within the housing 9. Said differential includes the gears 44 and 41 fixed to rotate with the gears 2| and 4|, respectively, and have the gears 45, 46 meshing therewith. Thus, with the shaft 25 rotating to drive the gears 2| and 44 and with the gears 4| and 41 stationary by reason of the non-rotation of shaft 43, the differential will effect rotation of the shaft 40 and its gear 38 to counteract the tendency of the shaft 31 to rotate in its bearings while it is turning with the member about the vertical axis of the latter.

The member i1 is positioned according to the angle of azimuth by rotating the shaft 23 proportionally to that angle, and the carriage 25, with the disc 26 carried thereby, is moved along the member I! by rotating the shaft 43 through an angle proportional to the angle of elevation. Thus, the magnetic disc 26 may be positioned ac- 4 cording to the angles of train and elevation received by shafts 23 and 43, respectively.

The input data representing train and elevation on shafts 23 and 43 which control the position of the member I! and carriage 25 is converted into output data of roll and traverse in the manner that will now be described. The sleeve 12 supported by the standard H] has a hollow shaft 48 extending therethrough which, as seen in Fig. 3, has an extension 49 secured thereto. This extension carries a pin 50 projecting therefrom upon which the gear 5| is free to rotate, and said gear carries the servo arm 52 associated with the magnetic disc 26 in a manner presently to be described. The pin 50 is located so that the center line 53 therethrough will intersect the line 54 through the center of the sleeve |2 at the point 55 which lies at the center of the sphere which is generated by the rotation of the member I! on its axis. Within the shaft 48 there is journaled a second shaft 56 that is free to be rotated relative to the shaft 48 and which carries a gear 51 meshing with the gear 5!. The outer shaft 48 is driven by the gear 58 from the shaft 59 and gears 69, 5| connected to the two-phase motor 62. The inner shaft 56 is driven by the gear 63 meshing with the gear 64 on the shaft 65 which is operated by the gears 66, 6! coupled to the two-phase motor 58. Operation of the motors 62 and 68 is controlled in a manner to later appear.

When the motor 68 is driven, the shaft 55 causes the arm 52 to be turned in an are about the pin 50 as an axis to select the angle of traverse that said arm will occupy, and operation of the motor 62 will effect rotation of the shaft 48 to roll the gear 5| about the axis of the gear 51 and thus select the angle of roll which said arm is to occupy. In order that the coordinate movements of the arm 52 may be properly effected by the two drives from the motors 52 and 63, said drives are interconnected by a differential mounted within the housing formed by the plates l3 and I4 and which functions in the same manner as the differential previously described in conjunction with the input shafts 2'3 and 43.

Said differential comprises the gears H and i9 fixed, respectively, to the gears 63 and 69 and meshing with the idler gears 10 and I2. Positioning the arm 52 so that the arm is directed at the magnetic member 26 involves displacing said arm in traverse and rotating it in roll, and thus the rotation of the driving motors 82 and 68 will be proportional to the angles of roll and traverse, respectively.

In order that the motors may be energized so that the arm 52 will track with and be maintained constantly directed toward the magnetic disc 26, said arm is provided at its free end with a lateral extension 14 to which is secured a plate 14a including four equidistantly spaced arms (Fig. 4). Said plate carries five identical coils l5, 16, 11, I8 and 19 having iron cores, with the energizing coil 15 disposed centrally of the plate and the remaining pick-up coils being arranged at the extremities of the arms of said plate. The distance between opposed extremities of the arms of said plate 14a is less than the diameter of the disc 26, and an air gap is provided between the outer extremity of the coils and said disc.

As will be seen from Fig. 6, the energizing coil 15 is connected to and constantly energized by leads and 8| connected to a source of alternating voltage L and said coil will thus generate an alternating magnetic field which will be conducted by the disc 26 and induce equal voltages in each of the pick-up coils I6, 11, I8 and I9 when they are symmetrically positioned with respect to said disc. Coils II and I9, which may be called the traverse coils, are interconnected, by means of lead 82, so that their voltages are opposed to each other and the sum of these voltages, when the voltage output of each of the coils is the same, is zero. The sum voltage of the coils I1 and I9 is connected by leads 83 and 84 to the amplifier 95 which, by way of leads 80, BI, is energized from the line L. The output voltage of the amplifier 85 on the leads 86 and 81 is connected to one phase of the two phase motor 68 whose remaining phase is returned to the line L. Coils I6 and I8, which may be called the roll coils, are connected by. a lead 88 and the sum of their opposed output voltages in the leads 69 and 90 is fed to the amplifier 9| which is also energized from the line L. Output voltage of the amplifier 9| on leads 92 and 93 is then used to energize one phase of the two-phase motor 62 whose remaining phase is energized from the line L.

Any new inputs of azimuth and elevation introduced into the mechanism from the shafts 23 and 43 will, by the resultant movements of the members [I and 25, displace the position of the disc 26 to correspond to the new inputs. disc is so displaced, the coil structure I5 to I9 will momentarily be non-symmetrically disposed with respect to said disc and the voltages representing the sum of the coiled pairs will no longer be equal to zero in view of the fact that the reluctance of the magnetic path between the energizing coil I5 and the pick-up coils I6 to I9 will differ. This difference voltage will energize the appropriate motor 62 or 68 so that the arm 52 will be driven to correspondence with, or in exact positional relation to, the disc 26, whereupon the motors will stop and the position of the motor shafts 94, 95 may then be read as the new angles of traverse and roll which correspond to the new input coordinates of elevation and azimuth.

From the foregoing, it will be seen that the invention provides a mechanism which will be responsive to both inputs of azimuth and elevation and will convert them into roll and traverse by the displacement of the disc 26 relative to the associated coil structure so that the servo arm 52 will move about its roll axis and through a traverse angle to maintain alignment of said disc and arm, and that the mechanism is so constituted that there is no null at which said arm will fail to follow said disc or any position from which the arm cannot move.

With previous devices of this nature, as well as with gun mounts which have only two degrees of freedom, 1. e. in which the gun is mounted in trunnions which are rotatable about a vertical axis thru the center of the gun mount, there exists a point (the null mentioned above) at which the gun mount or the converting mechanism is in a locked position. Such a position would be one similar to the position (Fig. 2) of arm 52 if it were extended to the right directly in line with the axis of shaft 56 and if its outer end, upon which the coils 11, etc. are mounted were rigidly attached to the magnetic disc 29. In such a position as this, and under the above condition, if an attempt were made to rotate the sector II, no movement would be possible for the tendency would be to bend the arm 52. This would be the case with an axis converter which might have an As the arm equivalent to the present arm 52 but rigidly attached to the equivalent of the present trolly mechanism 26, etc.

This invention overcomes thisdifficulty, as has been generally pointed out above, by keeping the arm 52 separated from the trolly mechanism but electro-magnetically coupled to it. Thus, when the arm 52 reaches a position directly to the right as seen in Fig. 2 in which it is longitudinally aligned with shaft 56, if it is desired to move the segment H, such a motion may be completed Without resistance. The arm 52 will then follow the trolly mechanism because of the particular arrangement of the pickup coils I6-'I9, inclusive. Under the above conditions, when the sector II is rotated moving the trolly 25-26, etc. arcuately away from the traverse coils II and I9, the coil system becomes unbalanced as to roll coils I6 and I8, that is to say, if segment I! rotates in such fashion that the magnetic disc 26 moves away from the observer as seen in Fig. 2 and parallel to a center line common to the roll coils I6 and I8, the effect will be to diminish the current of coil I8 and to increase the current ofcoi1 I6 leaving the currents of traverse coils I1 and I9 diminished but equal to each other. This condition, through amplifier M, (Fig. 6) will immediately cause roll motor 62 to turn the arm 52 about its longitudinal axis. When this occurs, the arm 52 will immediately be free to follow the disc 26 and thus attain its proper position according to the new input. It is to be particularly noted that since the gun contemplated in conjunction with the present invention is mounted for rotation about two axes and two axes only, its action will be precisely the action of arm 52 which may be considered to be a dummy gun. This means that the gun itself will roll with the arm 52 and then follow said arm in traverse.

From the foregoing, it is seen that the present invention provides a means of eliminating the usual null or looking position of a gun which is mounted for rotation about two axes at right angles to each other and that it further provides an axis converting mechanism having a dummy gun which is followed in movement precisely by the real gun.

It is further to be understood that the word null as hereinbefore mentioned means thatcondition of a gun or similar object, mounted in the usual pair of trunnions for rotation about an axis through a center line common to both trunnions which trunnions are rotatable in a plane parallel to said axis, when the longitudinal axis of the gun and the trunnion axis lie in a plane perpendicular to the aforementioned plane and when it is attempted to move the gun in the last mentioned plane. this condition would occur when the gun pointed straight up away from the center of the earth, and would occur in the nose gun of a plane when the longitudinal axis of the gun coincided with the longitudinal axis of the body of the aircraft.

What is claimed is:

1. In an axis converter mechanism for guns, input means therefor responsive to data of azimuth and elevation, output means for said mechanism identifying data of roll and traverse, means operativelyconnected to said input and output means and controlled by saidinput means to convert said data of azimuth and elevation into data of roll and traverse and to transmit the latter data to said output means, said operative means including cooperating members each controlled by one of said input means and one supported y In an ordinary deck gun on shipboard,

the other and having movement about diiferent axes to describe arcuate paths both in excess of 180, the resultant of said movements indicatin a direction, a device operatively associated with said members and including a magnetic element carried by one of said members, a coil structure coacting with said magnetic element in opposed spaced relation thereto and influenced by variations in the reluctance between said element and the coils of said structure created by movement of said members relative to said coils to maintain said opposed relationship, and connections between said coil structure and said output means for operating the latter in accordance with the direction indicated by the movements of said members.

2. In an axis converter mechanism for guns, input means therefor responsive to data of azimuth and elevation, output means for said mechanism identifying data of roll and traverse, means operatively connected to said input and output means and controlled by said input means to convert said data of azimuth and elevation into data of roll and traverse and to transmit the latter data to said output means, said operative means including cooperating members each controlled by one of said input means and one supported by the other and having movements about difierent axes to describe arcuate paths both in excess of 180, the resultant of said movements indicatin a direction, a device operatively associated with said members and including a magnetic element carried by one of said members, a coil structure including a central energizing coil and a plurality of pick-up coils arranged symmetrically about said energizing coil and relative to said magnetic element, said coils coacting with said magnetic element in opposed relation thereto and controlled by variations in the reluctance between said element and the pick-up coils of said structure created by movement of said members relative to said coils to maintain said opposed relationship, an arm supporting said coil struc ture and having movements about two different axes, driving means for said output means coupled to said arm and controlled by said variations in reluctance to drive said output means and to move said arm about its axes in accordance with the resultant movements of the first named cooperating members.

3. In an axis converter mechanism for guns, input and output means for said mechanism, two driving means for said output means, a supporting structure for said mechanism, a sleeve member extendin laterally from said supporting structure, inner and outer shafts journalled in said sleeve member and each coupled to one of said driving means, an arm connected to one of said shafts for rotative movement about the axis thereof, gearing coupling the other shaft to said arm for rotating the same about a different axis, an arcuate member mounted in said supporting structure for rotative movement therein limited only by contact of said arcuate member with said sleeve member, operative connections between one of said input means and said arcuate member, a carriage mounted in said arcuate member for movement therewith and also movement relative thereto in an arcuate path in excess of 180, operative connections between the other input means and said carriage for moving the latter relative to saidarcuate member, a magnetic element mounted on said carriage for movement therewith, a coil structure carried by said arm in opposed and spaced relation to said magnetic element and including a plurality of pick-up coils symmetrically arranged relative to said magnetic element, and means connecting said pick-up coils with said driving means to operate the latter upon variation in the reluctance between said magnetic element and said coils.

4. A servo mechanism for use in an axis converter wherein two members are movable about difierent axes, said mechanism comprising a device operatively associated with said members and includin a magnetic element carried by one of them, a coil structure including a central energizing coil and a plurality of pick-up rolls arranged symmetrically about said energizin coil and relative to said magnetic element, said coils coacting with said magnetic element in opposed relation thereto and controlled by variations in the reluctance between said element and pick-up coils created by movement of said members relative to said coils to maintain said opposed relationship, means to support said coil structure and having movements about different axes, and means controlled by said variations in reluctance to move said structure supporting means about its axes.

5. In an axis converter wherein two members are movable about diilerent axes, an arm having movements about different axes, a device operatively associated with said members and includin means positioned in opposed relationship to said arm, means on said arm to electro-magnetically couple said arm to said opposed means to move said arm about its axes in response to movement of said members.

6. In an axis converter wherein two members are movable about different axes, a device operatively associated with said members, an arm, means operable to r011 said arm about one axis, means operable to move said arm traversely about another axis, electro-magnetic coupling means on and between said arm and said device including a pair of roll coils and a pair of traverse coils, said roll means and said traverse means bein controlled by variations in reluctance between said roll and traverse coils respectively and said device to move said arm about its diiferent axes.

'7. In an axis converter wherein two members are movable about different axes, a device operatively associated with said members and includlllg a magnetic means carried by one of them, a coil structure including a pair of roll coils, an energizing coil for inducing equal voltages in said roll coils, said voltages in said roll coils varying in response to movement of said magnetic means, means for supplying pulsating current to said energizing coil, means under control of said roll I coils for indicating the coordinate of roll, and means supporting said coil structure having said energizing coil, said coils coacting with said magnetic means in opposed relation thereto and controlled by variations in the reluctance between said magnetic means and coils created by movement of said members relative to said coils to maintain said opposed relationship, and means to support said coil structure having movements about difierent axes in response to the variations in reluctance.

9. In an axis converter wherein two members are movable about different axes, a device operatively associated with said members and including a magnetic means, a coil structure comprising a pair of traverse coils, an energizing coil for inducing equal voltages in said traverse coils, said coils coacting with said magnetic means in opposed relation thereto and controlled by variations in the reluctance between said means and traverse coils created by movement of said members relative to said coils to maintain said opposed. relationship and means to'support said coil structure having movements about different axes and moved traversely in response to the variations in reluctance.

10. In an axis converter wherein two members are movable about different axes, a device operatively associated with said members and including a magnetic means, a coil structure comprising a pair of roll coils, a pair of traverse coils, an energizing coil for said pairs of coils for inducing equal voltages in said roll coils and said traverse coils, means for supplying pulsating current to said energizing coil, said coils coacting with said magnetic means and controlled by variations in 10 the reluctance between said magnetic means and said coils created by movement of said members relative to said coils, means to support said coil structure, said support means having movements about diiiferent axes in response to the variations in reluctance.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,751,649 Nieman Mar. 25, 1930 1,880,174 Dugan Sept. 27, 1932 2,069,417 Murtaugh Feb. 2, 1937 2,094,039 Kinsley Sept. 28, 1937 2,339,508 Newell Jan. 18, 1944 2,399,675 Hays May 7, 1946 2,462,081 Esval Feb. 22, 1949 2,492,244 Shivers Dec. 27, 1949 2,586,817 Harris Feb. 26, 1952 FOREIGN PATENTS Number Country Date 204,661 Switzerland Aug. 1, 1939 366,076 Great Britain Jan. 29, 1932 421,315

Great Britain Dec. 18, 1934

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