US1339643A

US1339643A - Apparatus for the conversion of motion of one type into motion of another type

Info

Publication number: US1339643A
Application number: US250087A
Authority: US
Inventors: Barr Archibald; Stroud William
Original assignee: Thales Optronics Ltd
Current assignee: Thales Optronics Ltd
Priority date: 1918-08-15
Filing date: 1918-08-15
Publication date: 1920-05-11
Anticipated expiration: 1937-05-11

Description

A. BARR AND w. snoun.

`PPARATUS FOR THE CONVERSION 0F MOTION 0F ONE TYPE INTO MOTION OF ANOTHER TYPE.

APPLICATION FILED MIG. I5, I9I8.

1,339,643 v Paten (1M 11,1920. /mF/f///,f f f6/@fw 6%- f4/f I L r s El ' UNITED STATES PATENT OFFICE.,

ARCHIBALD BARR AND WILLIAM STROUD, OF GLASGOW, SCOTLAND, ASSIGNORS T0 BARR AND STRO'UD LIMITED, OF ANNIESLAND, GLASGOW, SCOTLAND.

APPARATUS FOR THE CONVERSION :0F MOTION OF ONE TYPE INTO MOTION 'iO-F ANOTHER TYPE.

Specficationof Letters Patent.

Patented May ,11, 1920.

Application filed August 15, 1918. Serial No. 250,087.

To all whom t may concer/t Be it known tha't we, ARCHIBALD BARR and IILLIAM S'rRoUD, subjects of the 'King of Great Britain and Ireland, and both of CaXton street, Anniesland, Glasgow, Scotland, have invented new .and useful Improvements in Apparatus for the Conversion of Motion of one Type into Motion of Another Type, of which the following is a specification. A

The object of our invention is to provide improved means for the conversion of motion according to one law (or type) into motion according to another law l(or type). For example, it provides means for the conversion of motions in accordance with those of the working Vhead of a .constant base rangefinder-which commonly follow the reciprocal law with reference to changes in range-into motions proportional Y Vto the changes of range, t'. c., kthe conversion of motions according` to a reciprocal scale into motions according to a uniform scale; or again, for the conversion of motions ,according to a uniform scale of ranges into motions according to a logarithmic scale, or according to a scale of gunsight elevations corresponding to the ranges; or for other analogous purposes.

Patents with the same lobject in view are well known, but in mechanism generally for effecting such conversions of motions a difficulty arises when the velocity-ratio lvaries over wide limits at different parts of the conversion, c. g., to convert a reciprocal scale of ranges extending from 3,000 to 30,000 yards into a uniform scale, with the velocity-ratio varying from 1 to 100, in one stage, the size of the mechanismrequired as at present known, for sufficient accuracy, would necessarily be great. A method has been pro- .'icsed to effect conversions of this charactery in two (or more) stages, each, say, of 1 to 10, whereby a reduction in the vsize of the mechanism required is obtained.

Our present invention has for its object improvements in or connected with apparatus and the pro'ductionof improved apparatus for use in the conversion ofmotion according to one law (or type) into motion according -to another law (or type) in which the velocity-ratio may vary over wide limits (say, 1 to 100) at different parts of the conife'rsion, by means of which apparatus the conversion inaybe'effected in one stage', and

the apparatus produced maybe of small dimensions .in comparison `with mechanisms generally known for such purposes. Moreover, a novel process of conversion is made possible with the use of apparatus according -to this invention in which the velocityratio kmay be furnished, where @c denotes the motion'applied to the apparatus, y the emergent motion and Hm) is any function of m.

Apparatus according to this invention comprises three gear elements constituting a main differential gear with means for applying to the first and second elements forces tending to drive them in opposite senses so far as their effects on the third element are concerned, associated with mechanism for controlling the ratio of the motions imparted to the first and second'elements in a pre determined progressively variable manner, whereby, for example, the motion of thel first or the second element may be in accordance with the law A to be converted and the motion of the third element in accordance with the law B desired, or the motion of a part of mechanism provided 'for driving the first and second elements may be in accordance with the law A and the motion of the third element in accordance with the law B.

Denoting the elements of an 'ordinary differential' gear by 1, 2, 3 in which 2 is the jockey element, 'it is clear that if the ,ele-

ments 1 and 3 are geared together in some suitable non-uniform way and provision as small as desired by adopting suitable nonuniform controlling gear, in fact, .it may be made Zero by arranging that the velocity of 1 is equal and opposite to that of 3. Further, the velocityiatio of 2 may be'made negative compared with (say) 1, in the following way If 1 is moved forward at a certain rate and 3 backward at 'a Ysmaller rate, then we may regard 2 as moving Vforward .at a rate depending on the differences of the rates of1 and 3. As soon as the rate of motion of 3 equals that of 1, 2 becomes stationary, while if thel rate 'of '3 exceeds that of 1, 2 will move backward. By our invention it is thus possible to make 2 move in any prescribed manner forward or backward as may be desired. Further, in this way, if ae denotes the motion imparted to the mechanism and g/ the emergent motion it is possible to obtain a mechanical solution of the equation yzf whatever the form of this function.

Taking then, as an example, the case of the conversion of a reciprocal scale of ranges into a uniform scale, we may gear the jockey element 2 of the differential gear to the working head of a rangefinder while we actually work by hand either the element 1 or 3. If then 1 and 3 be geared together in some suitable non-uniform way so that 3 moves in the opposite direction to 1, when, say, 1 is turned by hand, we may arrange that each revolution of 1 shall correspond to a definite change of range.

In certain cases it is conceivable that there may be a considerable resistance to the motion of 2, in which case considerable forces will have to be transmitted through the non-uniform gear between 1 and This objection may be overcome by applying a direct drive to each of the elements 1 and 3. For instance, this may be done by providing a supplementary differential gear with an idle wheel, in which case a main

differential gear

1, 2, 3 and a supplementary

differential gear

11, 21, 31 are employed, 2 and 21 being the jockeys, 1 being directly geared to 11, and 3 being geared to 31 through an idle wheel. If now we apply a drive to 21 (according to a uniform scale) and obtain our drive to the rangefinder from 2 by suitable non-uniform gearing be tween 1 and 3 (as before) we may arrange that the motions of 2 shall be according to the required reciprocal scale. In ythis case 2Y moves in accordance with the difference in the motions of 1 and 3 which are each directly driven, the non-uniform gear between 1 and 3 being employed to regulate the relative motions of 1 and In this way the force transmitted through this non-uniform gear is appreciably reduced.

In the use of differential gears as above described, we have assumed that the drives are imparted to 1 and 3, and the part driven is connected to the jockey element 2, but in all casesY as is well-known in connection with differential gears) the drives may be imparted to any two of the three elements of the gear provided their effects on the third element are in opposite senses, while the third element is connected to the part to be driven. 4

Examples of construction according to this invention will now be described with reference to the accompanying drawing, in which Y Figuresl, 2 and 3 are diagrammatic plan views. Fig. 4 represents a section ofone form which the gear may take. Fig. 5 shows in' side view a portion of the gear, and Fig. 6 is a plan of a detail. V

In the drawing, 1, 2, 3 designate the elements of the main differential gear, and 11,

11, 31 the elements of the supplementary differential gear.

In Fig. 1 force is applied to a handle 5 to which the spindle of jockey 21 is hXed, thus the bevel wheels 11 vand 31 tend to turn in the same sense. Fixed to 11 and 31 respectively are gear wheels f5 and 7. Gear wheels S and 9 are fixed to bevel wheels 1 and 3 respectively while 8 gears directly with G, and 9 (through an idle gear wheel el) with 7. Thus under the influence of the force applied to 5 the bevel wheels 1 and 3 tend to turn in opposite senses so that the motion of jockey wheel 2 (and shaft 10) is de- 1 and 3. VIn Fig. 1 there is no device shown for controlling the relative motions of 1 and 3. In Fig. 2, however, mechanism is indicated for controlling the relative motions of 1 and 3. Here wheel 8 gears with a wheel 141 to which a bevel wheel 11 is fixed. Bevel wheel 11 gears with a bevel 12 whose spindle is fixed, and bevel 12 gears with a bevel 13 to which a toothed spiral 15 is fixed. Spiral 15 gears with a complementary toothed spiral 17 fixed to wheel 9. The two

spirals

15 and 17 determine by their form the nature of the motion imparted to shaft 10. In the position shown in the figure spiral 17 will turn through a much large? angle than spiral 15, /ie., wheel 9 will will turn through a much larger angle than wheel 8 and consequently in the position shown shaft 10 will turn in the same sense as wheel 9. This occurs when the place of gearing 16 of the two spirals is nearer the spindle of9 than the spindle of 13. If the place of gearing 16 is, however, nearer the spindle of 13 than the spindle of 9 the shaft 10 will turn in the same senseas wheel 8. Thus as shaft 5 is turned in one sense shaft 10 will move (say) forward then stop and will then move back-ward.

In Fig. 1 (for which Fig. 3 is a diagrammatic representation) there is shown a section of the gear as applied (say) to the conversion of thegreciprocal scale of a rangefinder into a uniform scale. In this case as the handle 5 is turned in one sense the shaft 10 will likewise have to move always in one sense, e., notbackward at one part and forward at another part. The speed of the wheel 1 is in all circumstances greater than that of wheel 3 (andl their motions are in opposite directions) so that the .speed of shaft 10 which depends on their difference in speed never falls to zero. InFig. t the shaft 10 is used as the bearing for a toothed .helicospiral member 2O sol thatrlO and 2O termined by the difference in the motions of can rotate independently. Considering Fig. 3, the functions of

theparts

1, 2,3, 11, 21, 31,

` etc., with the exception :that Gand 8 are geared together lby 6 gearing with a gear wheel 81 fixed to 8, correspond to those of similar parts in Fig. "2, Abut instead of the controlling mechanism consisting of the two

spirals

15 and 17 of Fig. 2, we have two toothed helico-spiral members 20 and y21 with an idle whee'l22 whose center is capable of motion in two dimensions in the plane of the paper. If 'the two helico-spiral members 2O and 21 are correctly formed motions of the member 2() and the

gears

9, 3, 4 and 7 all directly geared together are according to a uniform scale while motions of the shaft 10 may be arranged to be in accordance with a reciprocal scale, thus when idle wheel 22 is `gearing with the teeth on the large radius of'20 and with the teeth on the small radius of 21 (as shown in Fig. 4) any motion `of 7 which is lfixed to shaft 30 will producea relatively large `motion of 21 and therefore of bevel wheel 1 geared to v21 through

wheels

14 and 8 and a relatively small motion of 2O and therefore of bevel wheel 3. It will vbe seen that 1 and 3 `move in opposite senses `so that ythe motion of 2 is determined by the motion of one vless that of 3. Vith the idle wheel 22 inthe position shown at Fig. 4 when handle 5 is turned shaft 10 will rotate rapidly backward rela tive to 20. If, however, idle wheel 22 Vis gearing with the teeth on the small vradius of 20 and with the teeth on .the large radiusV of 21 then the condition will be reversed and shaft 10 will now rotate slowly while i 20 will be rapidly turned. Tf now shaft 10 be geared to the working head of a range.- finder then starting from the position of the idle wheel 22 shown in Fig. 4, if we suppose handle 5 to be uniformly turned, shaft 10 is movedV rapidly at the start (corresponding to low ranges), it gradually gets slower and slower as idle wheel 22 moves vto the left 'in Fig. 4 and approaches shaft 1() until `when 22 is nearest shaft 10 this shaft will be slowly rotating (corresponding to Y the highest range for which conversion is desired). In Fig. 4 it will be seen that the convolutions on the left of the two helicospiral members are so arranged that the Vidle wheel 22 first approaches shaft 10 and then rapidly vrecedes from it. This is with the object of enabling the'operator to rap idly approach the infinity position vof the i-nstrument.

Taking Fig. 4 in detail, wheel 7 is fixed to rotate with `shaft 3() whose right hand bearing is supported by `the shaft 31 to which handle 5 is fixed. Wheel 7 gears through idle wheel'4 with wheel 9 which is fixed to the helicofspiral member. All the

parts

7, 4, 9 and 20 move in accordance with a uniform scale so that ifit is desired to transmit the indication of the :instrument to a distance in uniform steps it is suflicient to actuate a step-by-step transmitter by the sha-ft 30.

In order to suitably support the floating idle'wheel 22 between the two helico-spiral members we may use the arrangement shown in Fig. 4. In this case the helico-spiral 2O is fixed axiallyand carries a wheel 33 gear-y ing with an equal wheel 35 through .idle wheel 34. theel 35 is fixed to shaft -36 upon which there is cut a screw lthread 37 whose pitch is equal to the pitch of the spirals of part 20. Helico-spiral 21 is moved axially due to the rotation of screw 37 A(upon which it -is mounted as a-nut) and is also 'moved axially -due to its own rotation on thel screw. Now, if ythe :idle wheel 22 is carried toward the 'left so as to keep in mesh with the spiral 2O the helico-spiral 21 willv move the appropriate amount to keep in mesh with the idle wheel.

In Fig. y5 is shown a side view of the support for the idle wheel 22 so designed as to move this idle wheel axially so as to maintain meshing. Its spindle is mounted on yav frame 41 suitably guided so as to `.be incapable of rotation about the axis .of a rod 42 upon which it can freely slide. Rod 42 is Vfixed to a nut upon screw lel to and behind shaft 10 but not shown in Fig. 4. A wheel 44 ygears with wheel 33 so that as the member 2O is lrotated 33 drives 44 and rotates 43 thereby translating lthe frame 41, perpendicular to the paper `in Fig. 5 and parallel to the paper in Fig. 4, the pitch of the screw "43 and the'ra'tio of the

gearing

33, 35 being ysuitably chosen to cause 22 to remain in continuous mesh with .the two helico-spirals'20 and 21.' This condition is satisfied by the screw 43 being geared to the helico-spiral 2O by gearing in theinverse ratio of .the pitches of the screw 43 and .member `20, while rotation is imparted to the screwed sh aft 36 proportional to the rotation of the helico-spiral 2O in such 43 placed paral a way that the axial translation of the member 21, due to the rotation of the screw 36, is proportional to the angular rotation of the member 20, while the member'21has also an axial translation proportional to kits own'rotation on theV shaft 36, on which it is threaded as a nut. t

Inasmuchl Ias the helico-spiral 21 goes axial displacement in the operation of `the apparatus and wheel 14 and member 21 mentioned that the luniform scale portion of the mechanism is geared to bevel wheel 3j under- Y so that one revolution of the handle 5 does not correspond to the same change in range at all parts of thetravel. The mechanism could, however, be designed so that the unin form scale portion of the mechanism Was geared directly to handle 5.

1n the above We have described the application of our invention to a problem met With in connection with rangefinders Where it is desired to convert motion according to a reciprocal scale of ranges into motion according to a uniform scale. This is done only by way of illustration and We do not confine ourselves to this particular application of the invention which may be used in other cases for the conversion of motions Within limits as to the extent of these motions, z'. e., it is not a mechanism Which can convey motion from one shaft to another continuously.

We claim: y

1. Apparatus comprising three gear elements constituting a main differential gear, means for applying to the first and second elements forces tending to drive them in opposite senses so far as their effects on the third element are concerned,.associated with mechanism for controlling the ratio of the motions imparted to the first and second elements in a predetermined progressively varying manner, for the purposes set forth.

2. Apparatus comprising three gear elements constituting a main differential gear, and three gear elements constituting a supplementary differential gear, the first and second elements of the supplementary gear being in driving connection with the first and second elements of the main gear respectively, means for imparting motion to the third element of the supplementary gear, the said driving connection being such that forces are transmitted to the first and second elements of the supplementary gear Ytending to drive the first and second elements of the main gear in opposite senses so far as their effects on the third element of the main gear are concerned, associated with mechanism for controlling the ratio of the motions imparted to the first and second elements of the main gear in a varying manner, for the purposes set forth.

3. Apparatus comprising three gear elements constituting a main differential gear, means for applying to the first and second elements forces tending to drive them in opposite senses so far as their effects on the third elementare concerned, associated With mechanism for controlling the ratio of the motions imparted to the first and second elements in a `varying manner so that the motion of one of the first and second elements is inaccordance with the lavv of motion A to be converted and thatofthe third element is in accordance with the laW of motion'B desired, substantially as set forth.

t. Apparatus comprising three gear elements constituting a main differential gear, and three gear elements constituting a supplementary differential gear, the first and second elements of the supplementary gear being in driving connection With the first and second elements `of the main gear respectively, means for imparting motion to the third element of the supplementary gear, the said driving connection being such that forces are transmitted to the first and second elements of the supplementary gear tending to drive the first and second Velements of the main gear in opposite senses sol far as their effects on bthe'third element of the main gear are concerned, associated with mechanism for controlling the ratio of the motions imparted to the first and second elements of the main gear in a varying manner so that the motion of one of the elements of the supplementary gear is in 4accordance With the lavv of motion A to be convertedV and that of the third element' of the main gear is in accordance with the law of motion B' desired.

5. Apparatus comprising three gear elements constituting a main differential gear, means for applying to thefirst and second elements forces tending to drive them in opposite senses so far as their effects on Vthe third element are concerned, associated with mechanism comprising toothed-spiral mem-V bers for controlling the ratio of the motions imparted to the first and second elements in a varying manner, for the purposes set forth.

6. Apparatus comprising threegear elements constituting a main differential gear, means for applying to the first and second elements forces tending to drive them in opposite senses so far as their effects on the third element are concerned, associated with mechanism comprising tivo toothed helicof spiral members, associated With means for imparting aXial translation to one of the members and for imparting rotational motion to each, for controlling the ratio of the motions imparted to the first and second ele'- ments in a varying manner,for the purposes set forth.

7. Apparatus comprisingV three gear elements constituting a main differential gear, and three gear elements constituting a supplementary differential gear, the ,first and second elements of the supplementary gear being in driving connection with the.y first and second elements ofthe main gear respectively, means for imparting motion to the third element of the supplementary gear, the said driving connection being such that forces are transmitted to the first and second elements of the supplementary gear tending to drive the` first and second elements of the main gear in opposite senses so far as their effects on the third element ofthe maingear are concerned, associated With mechanism comprising toothed spiral members for controlling the ratio of the motions imparted to the first and second elements of the main gear in a varying manner, for the purposes set forth.

8. Apparatus comprising three gear ele# ments constituting a main differential gear, and three gear elements constituting a supplementary differential gear, the first and second elements of the supplementary gear being in driving connection With the first and second elements of the main gear respectively7 means for imparting motion to the third element of the supplementary gear, the said driving connection being such that forces are transmitted to the first and second elements of the supplementary gear tending to drive the first and second elements of the main gear in opposite senses so far as their effects on the third element of the main gear are concerned, associated with mechanism comprising two toothed helico-spiral members, associated With means for imparting axial translation to one of the members and for imparting rotational motion to each for controlling the ratio of the motions imparted to the first and second elements of the main gear in a varying manner, for the purposes set forth.

9. Apparatus comprising three gear elements constituting a main differential gear, means for applying to the first and second elements forces tending to drive them in opposite senses so far as their effects on the third element (the jockey) are concerned, associated With mechanism for controlling the ratio of the motions imparted to the first and second elements in a predetermined progressively varying manner, for the purposes set forth.

10. Apparatus comprising three gear elements constituting a main differential gear, and three gear elements constituting a supplementary differential gear, the first and second elements of the supplementary gear being in driving connection with the first and second elements of the main gear re spectively, means for imparting motion to the third element (thejockey) of the supplementary gear, the said driving connection being such that forces are transmitted to the first and second elements of the supplemen` tary gear tending to drive the first and second elements of the main gear in opposite senses so far as their effects on the third element (the jockey) of the main gear are concerned, associated with mechanism for controlling the ratio of the motions imparted to the first and second elements of the main gear in a varying manner, for the purposes set forth.

`ARCHIBALD BARR. WVILLIAM STROUD.

Witnesses J Aims WEIR FRENCH, FRANCIS MORRISON. y