US2360053A - Timing apparatus - Google Patents

Description

Oct. 10, 1944.

T. B. GIBBS 2,360,053

TIMING APPARATUS 4 Sheets-Sheet l 1 Filed March 24, 1941 INVENIOR. 7210/22 as Z3. Gbb',

Wi W Oct. 10, 1944. 555 2,360,053

TIMING APPARATUS Filed March 24, 1941 4 Sheets-Sheet 2 INVENTOR. Thomas B Gibbs Oct, 10, 1944. T @1555 2,360,053

' I'IMING APPARATUS Filed March 24, 1941 4 Sheets-Sheet 5 Oct. 10, 1944. T. B. GIBBS TIMING APPARATUS 4 Sheets-Sheet 4 Filed March 24, 1941 RUN INV ENT OR.

VBY

Patented Oct. 10, 1944 TIMING APPARATUS i Thomas B. Gibbs, Delavan, Wis., assignor, by

mesne assignments, to George W. Borg Corporation, Chicago, 111., a corporation of Delaware Application March 24, 1941, Serial No. 385,029

28 Claims. (Cl. 73-6) 1 The present invention relates in general to timing apparatus, and more in particular to apparatus for timing or checking the rate of mechanical fuses such a are used in shells. A fuse of this type includes a clockwork mechanism which is driven by power developed by centrifugal force acting on a pair of weights during rotation of the shell in its flight. The -clockwork mechanism can be driven from another power source before the fuse is completely assembled, but the rotation of the shell affects the rate, and consequently it is desirable to carry out the timing operation while the fuse is undergoing rotation.

A specific object of the invention, therefore, is

to provide an apparatus for timing a fuse of the mechanical or clockwork type while it is being rotated at a high speed, approximately 16,200 R. P. M., in order to simulate its operation when the shell in which it will eventually be used is fired.

Other objects relate in general to the production of an improved timing apparatus having features of advantage in timing fuses and for other purposes.

The invention will be described hereinafter in connection with the accompanying drawings, in which Fig. 1 is a sectional view of a chuck for holding a fuse while it is being rotated, together with a guard and parts of an optical system which are mounted thereon;

Fig. 2 is a top view of a mechanical type of fuse;

Figs. 3 and 4 show details of the slot which is milled in one of the fuse plates;

Fig. 5 is a view showing the relation of the light source to the spinning motor and guard when a modified optical system is used;

Fig. 6 is a sectional view through the guard shown in Fig. 5, showing details 'of the chuck and modified optical system;

Fig. 7 shows details of the slots in the plates of a fuse by which it is adapted to be timed with the optical system shown in Figs. 5 and 6; and

Figs. 8 and 9 are diagrammatic circuit drawings of a complete fuse timing equipment.

Referring to Fig. 1, the reference numeral I indicates a portion of the top of a table where the timing operations are performed. The operator sits in front of this table and on it are mounted those parts of the equipment which require her attention, as well as other parts necessarily associated therewith.

Beneath the table top the motor 2 is mounted in suitable manner, with its shaft 3 vertical and projecting upward through an opening in the table top. The motor 2 is preferably of a type having a high starting torque and adapted to run on three phase alternating current at synchronous speed. 1

The chuck for holding the fuse is mounted on the end of the motor shaft and comprises two main parts, a receptacle for receiving the fuse and a cap for locking the fuse in position in the receptacle. The receptacle part of the chuck includes a flanged base portion 4, having an opening therein for receiving the shaft 3. The part 4 fits tightly on the shaft so as to be rotated thereby when the motor is running. Associated with the base 4 there is a cylindrical part 6, flanged internally, and a cup-shaped part 1. These parts are secured to the base 4 by means of screws such as l0, as shown in the drawings.

- 6 and I for receiving the open end of the cap 8.

There is also an annular space between the cylin drical member 6 and the base 4 and in this space there is fitted a flanged cylindrical member 5. The member 5 is slidable up and downand is normally held with its internal flange in engagement with the circular stop plate l3 by springs such as 9. The plate I3 is secured to the base member 4. The member 5 has a spline II which slides in the groove l2 and prevents rotation of member 5 relative to the other parts of the chuck.

The cap 8 is a cylindrical shell open at the lower end and partly closed at the upper end by an inwardly extending annular flange, as seen clearly in the drawings. The cap is removable from the chuck. When assembled in place the open end of the cap enters the annular space between the members 6 and l, where it is held by means of. a plurality of bayonet joints. One of these joints is shown on the section line in Fig. 1, and comprises the pin ll, rigidly fixed in the member 6, and the cooperating slot 1 6 which is cut in the skirt of cap 8. The shape of the slots can be seen from the dotted line showing of the next adjacent joint comprising pin l8 and slot I9. It will be understood that in practice there will be preferably three or four of these joints, equally spaced, and arranged to alternate with the screws such as I0.

A fuse of the type previously referred to is indicatedat l4. With the cap 8 removed, the fuse may be placed in the annular seat 20 which is formed at the upper end of the sliding member 5. The seat is provided with a projection (not shown) which fits in the recess ii at the lower end of the fuse, and accordingly the fuse must be turned until the recess and projection are in alignment before it can be properly seated. Th arrangement described prevents rotation of the fuse in the chuck and also insures that it will be placed in the chuck in the correct angular position as requiredby the optical system.

When the fuse has been properly positioned initsseatthecaplmaybeputon andisrotated imtil the pins such as 18 enter the slots such as IS. The upper seat 2| formed in the flange at the top of the cap thereupon engages the top of the fuse. The cap is now pressed down as far as it will go, the cylindrical member moving downward against the tension of springs 9, and is then rotated in a clockwise direction as seen from the top in order to engage the bayonet joints. The cap is thus locked in position and the fuse I4 is securely held between the lower seat 23 and the upper seat 2|.

The guard is indicated at 22 and is preferably a casting having substantial walls so as to provide adequatep'rotection to the operator. The guard is conveniently made large enough to afford space for mounting the first amplifier stage and is provided with a partition 23 which divides the interior into a guard section proper, which surrounds the chuck, and a housing section in which the parts of the first amplifier stage are located. These parts are not shown in Fig. 1, since the mounting arrangement may follow known practice.

The guard 22 is hinged to the table top, as indicated at 26. The provision of the hinge enables the guard to be rotated in a clockwise direction, as seen in Fig. l, in order to expose the chuck and give the operator access thereto. A handle may be ,providedat the side of the guard to facilitate its manipulation by the operator, or any other suitable means may be provided for this purpose. An opening 25 near the hinge permits the installation of a flexible cable carrying the necessary conductors for connecting with the amplifier. When the guard is in closed position, as shown in the drawings, it depresses a pin 25 and thus closes a switch comprising the contact springs 21 and 28.

The optical system includes a lamp 30 which is moimted in a suitable socket 3|. The latter is supported on a circular glass plate 32, which. in

turn is supported on the interior wall of the guard, as shown. A mask 33 isattached to the lamp socket and surrounds the lamp 30 in order to prevent general illumination of the interior of the guard. The circuit connections to the lamp preferably include two fine bare copper wires which extend along the top of the glass plate from the lamp socket to the opening 24 through which they pass into the amplifier housing, where they connect to conductors coming from a suitable source of current for lighting the lamp. These fine wires are not shown, but it will be understood that they may be secured to the glass plate in spaced relation by means of some transparent cement or gum such as shellac. Suitable sleeves are provided at the opening 24 and beyond.

The remainder of the optical system comprises a photo-cell 34, an annular mirror 36, and a refiecting surface of the fuse. The photo-cell 34 has a socket 35, which is mounted on the partition 23. The mirror is supported on the inp terior wall of the guard like the glass plate 32. In this connection it will be understood that the members 31 and 38 are preferably split cylinders of resilient material which are tensioned outwardly and thus grip the interior wall of the guard. The mirror 36 may be of metal and has a polished reflecting surface.

The arrangement of the fuse and its reflecting surface may be explained with reference to Figs. 2, '3, and 4. Fig. 2 is a general view of the fuse as seen from the top and shows the plate 40 having openings therein through which parts of the clockwork mechanism may be seen. These parts include the oscillatable balance or pallet arm 44, the two pallets 45 and 46, and the escape wheel 41. The pallet arm 44 is located in a recess in the plate 40 and when the clockwork mechanism is running it oscillates back and forth across the opening 48. The reflecting surface is indicated at 43 and is formed by milling a slot 42 in plate 4|, as shown in Figs. 3 and 4. This slot is so located that when the fuse is assembled the slot is centrally disposed with respect to the opening 48 in plate 40 and is covered by the end of the pallet arm 44 when the latter is in its central or at rest position. During oscillations of. the pallet arm the reflecting surface 43 is exposed to light from the lamp 30 through the opening 48, therefore, but during each beat of the pallet arm, when it passes through its midposition, the light is cut off.

It will thus be seen that the arrangement described provides for transmitting light from the lamp 30 by way of the opening 48, the reflecting surface 43 (when not covered by 44), the opening 50 in the wall of the cap 8, the annual mirror 36, and the transparent glass plate 32 to the photo-cell 34. When the,.iuse is rotated the path of the light rotates also, and generates a conical figure having its apex substantially at the cathode of the photo-cell. The light path is interrupted by the pallet arm of the fuse as it oscillates, and the pallet arm thus sends light impulses to the photo-cell which are employed to produce current variations in the circuit of the photo-cell. Although the rotating light path periodically crosses the wires previously mentioned as leading to the lamp socket 3!, these wires are so small that the transmission of light impulses by the oscillating pallet arm is not interfered with. Any photo-cell currents that are generated as a result of the partial interception of the light by the wires have a frequency which is difierent from that of the currents generated by the light impulses transmitted by the oscillating pallet arm, and are filtered out, as will be described subsequently.

It will be observed that the angular positioning of the fuse in its seat by the recess l5 insures that whenthe fuse is placed in the chuck the reflecting surface 43 will be adjacent to the opening 58in the cap 8.

Reference may. now be made to Figs. 5, 6, and '7, for a brief description of the modification shown in these figures.

Fig. 5 shows the general arrangement of -the guard, motor, and light source. The'motor 55 is suitably mounted beneath the table top 54,

as indicated in the drawings. Above the table top and suitably hinged thereto is the guard 60. The guard 60 may have an amplifier housing formed integrally therewith, as in the case of the guard 22, Fig. 1, but this housing and the hinges do not appear in Figs. 5 and 6 because of the fact that in these views the parts are rotated ninety degrees from the position in which the corresponding parts are seen in Fig. 1.

The shaft of the motor is indicated at 56, Fig. 5, where it will be seen that the shaft is hollow; that is, there is an axial bore extending clear through the shaft. Beneath the motor there is a lamp housing 6|, containing the lamp 62. The lamp housing maybe independently supported, or may be attached to the motor as shown. The lamp is mounted in a suitable socket connected to a source of current and is located in alignment with the motor shaft.

The chuck for holding the fuse is mounted on the upper end of the motor shaft 56 and comprises the base member 51, a cup-shaped member 63 secured thereto by screws, as indicated, and a locking cap 58. Inside of the cap 58 there is a slidable member 59 which is forced in a downward direction by means of a plurality of springs such as 64. When the cap is removed from the chuck the downward movement of member 59 is limited by a stop pin 65.

A fuse is indicated at I4. The cap 58 having been removed, the fuse is placed in the seat 66 of the chuck and is rotated until the positioning notch or recess 68 is in alignment with a corresponding projection (not shown) with which the seat is provided, whereupon the fuse will enter the seat properly. The cap 58 is then placed on the chuck and is rotated if necessary to enable the pins such as 69 to enter the slots such as I0. The top of the fuse is now engaged by the seat 61 formed in the sliding member 59, which moves upward in the cap as the latter is pressed down to engage and lock the bayonet joints. This operation is the same as described in the case of the cap 8, Fig. 1; that is, the cap is pressed down as far as it will go and is then rotated in the proper direction to lock the joints. The fuse is now firmly held between the seats 66 and 61.

The optical system comprises the lamp 62, Fig. 5, the photo-cell 34, located just above the guard as shown in Fig. 6, and a system of mirrors by means of which the light is directed from the lamp to the photo-cell over a path which is intersected by the oscillatable pallet arm of the fuse. The fuse is the same as the fuse shown in Fig. 2, except that the plates 16 and 11 have slots milled in them, as shown in Fig. 7. These slots are in alignment with the opening such as 48 in the top plate of the fuse and form a light passage which is closed by the pallet arm such as 44 when the pallet arm is in its mid-position. 1

The mirror system includes a mirror 12 which is secured to the chuck and receives light coming through the hollow shaft of the motor. Op-v posite the mirror I2 there is a slot II milled in the chuck as shown, and in this slot there is secured a mirror 13, which receives light, reflected from the mirror I2 and reflects it to a mirror 14. The latter mirror is secured to the inside wall of the cap 58 and reflects the light through the fuse (when the previously described light passage is not closed by the pallet arm) to the mirror I5, which in turn reflects the light through an opening in the top of the cap to the photocell 34'. The mirrors may be made of metal and have polished reflecting surfaces cut at the proper angles to reflect the light over the path described. The result is that the photocell is able to see the lamp, in a manner of speaking, except when the view is obstructed by the pallet arm in the fuse.

The arrangement shown in Figs. 5 and 6 may be used alternatively with that shown in Fig. 1. Each arrangement has certain advantages. The optical system of Fig. 1 is shorter and has fewer parts than that employed in Fig. 6. 0n the other hand, the optical system shown in Fig. 6 dispenses with a reflecting surface on the fuse, and the lamp is so located that its connecting wires are not crossed by the light path as the fuse is rotated. The arrangement to be used therefore rests in the sounder judgement of the designer or manufacturer, as influenced by the respective advantages of the two arrangements, and perhaps by other factors which need not be discussed.

Referring now to the circuit diagram, Figs. 8 and 9, the apparatus shown therein will be briefly described. I

At the left of Fig. 8 the motor 2 and chuck 4 for rotating a fuse I4 are shown diagrammatically, together with the essential parts of the optical system such as the lamp 30, mirror 36, and photo-cell 34. These are the same parts that are shown in Fig. 1. It will be understood that the modification shown in Figs. 5 and 6 may be substituted for Fig. 1 if desired.

The photo-cell 34 is located in the guard, as shown in Fig. 1, and is preferably of the type which includes a cathode in the form of a plate I00 and an anode in the form of a rectangular frame IOI.' The light beam passes through the frame and thus reaches the cathode without interference from the anode.

The reference character IIO indicates a preamplifier tube, preferably type 6C5, which is also located in the guard, or rather in the housing which forms part of the guard. A conductor I08 supplies plate voltage to the tube I I0 and also sup plies anode potential for the anode IOI of the photo-cell 34, to which it is connected by way of resistors I08 and I02. The photo-cell circuit thus includes the grounded cathode I00, the anode IOI, resistors I02 and I06, and conductor I08,

which is connected to the +B lead. The photocell circuit is coupled to the grid of tube III) by means of a condenser I03, said grid being provided with a grid leak I04. A cathode resistor I0! is provided in order to give the grid of the tube the proper negative bias. Condenser I05 is a bypass condenser.

The reference character I I I indicates an amplifier tube, which may be a type 6J7G pentode. The grid of tube I I I is coupled to the plate circuit of the preceding tube I I 0 by means of a condenser I09. It may be pointed out here that conductor I08 is preferably shielded after it leaves the guard, as indicated by the dotted lines. shielding and the guard should be grounded. The circuit arrangement for tube III is otherwise conventional and need not be described in detail. The next tube, indicated at I20, may be a type 605 tube and functions as an amplifier. The grid circuit of tube I20 includes a filter element comv prising the inductance I I4 and condenser I I5 and is coupled to the plate circuit of the preceding The The lower half of Fig. 8 shows the control cir-' cuits for the motor 2, which will now be described briefly.

The reference character S indicates a switch for starting the motor and is preferably a foot switch arranged so as to be conveniently accessible to the operator. The switch which includes contact spring 21 controlled by the guard is connected in series with the switch S, as shown.

The tube I38, which may be a type 6C5 triode, and its associated circuit elements constitute a time delay device, the operation of which will be described presently. A similar tube I48 and associated circuit elements constitute another time delay device. Relays I44, I46, and I52 are alternating current relays and operate on l10-volt commercial alternating current which is supplied over conductors I30 and I3I. Relays I39 and I49. are direct current relays and are connected in the plate circuits of tubes I38 and I48, respectively.

The rectangle indicated by the numeral I60 represents a motor generator set which may be of any well known type. The three phase output of this set is used to start the motor 2 and bring it up to its approximate running speed. The rectangle IBI represents a power amplifier or other source of three phase power having a constant frequency which is used for running the motor 2 during timing operations. A suitable power amplifier for this purpose is shown in the patent to Wickham, No. 2,333,502, granted Nov. 2, 1943. The motor generator set is used for starting because the motor 2 has to be accelerated very rapidly, requiring a considerable amount of power, which is provided more economically by a motor generator set. Ordinary commercial power cannot be used because its frequency is too low to run the motor at the proper speed. The arrangement shown permits the use of a power amplifier of much smaller capacity than would be required if a separate source of power for starting were not prow'ded, and is to be preferred mainly for this reason.

Referring now to Fig. 9, the upper half of this drawing shows a four stage frequency divider, such as is disclosed in Patent No. 2,304,813, Dec. 15, 1942, and comprising the tubes 200, 20I, 202, and 203. Each of these tubes may be a type 6N7 double triode, having suitable circuit connections whereby it operates as a multivibrator. The first stage multivibrator is controlled over conductor I26 from the plate circuit of tube 525, Fig. 8.

The output from the last multivibrator stage is used to'control the grid of tube 206, to which it is applied through a condenser 204 and resis tance 205. Tube 206 may be a gas filled tube, type 631P1.

The tube 206 is used to control a recording device, which maybe of the type which employs a toothed disk rotating at a constant predetermined speed and cooperating with printing means controlled by the impulses to be recorded to mark a moving strip of tape. This device will be briefly described.

The reference character 22I indicates a two phase synchronous motor, which rotates the toothed disk 235. The tape 230 is supplied from the roll 228 and is fed past the edge of disk 235 by a feed mechanism comprising the driven roller 224 and a. friction roller 225. Suitable guiding means (not shown) may also be employed to give the tape a curved formation at the point where It passes the edge of the disk. driven by a motor 220 through the medium of suitable speed reducing mechanism comprising the worm 222 and gear 223. The roller 22! is normally heldv slightly above roller 224 so that the feed mechanism is inoperative to advance the tape 230 which rests loosely on the roller 224. Roller 225 is lowered to press the tape against roller 224 and start the feed by means of a magnet 232, which also controls the circuit of motor 220 at contact springs 23'! and 230. The tape speed may be one inch per second. The tape is marked by means of a ribbon 245, which is fed across the tape where it passes the disk 235, and a printer bar 234. The latter has a curved lower edge and is actuated by the magnet 23I.

The motor 22I is supplied with power from a standard frequency source represented by the rectangle 2I6, which also supplies power to the motor 220. The standard frequency source may consist of a crystal oscillator, a frequency divider, and suitable amplifiers.

The tube 250 is an amplifier tube and is controlled over conductor I2I from the P e 01 cuit of tube I20, 8. The reference character 25I indicates a potentiometer, which is used for adjusting the control voltage applied to the grid of tube 250. -Tllbe 25I is also an amplifier tube and has its grid coupled to the plate circuit of tube 250 by means of a condenser 252. The plate circuit of tube 25I includes a relay 253, which controls the recording device.

The various tubes in Figs. 8 and 9, except tubes I38 and I40, are supplied with plate current from a suitable source of direct current connected to conductor 260, as will readily be understood. It will also be understood that known arrangements are provided for supplying current to the cathode heater circuits indicated throughout the drawings. a

The apparatus having been described, the operation of timing a fuse will now be described.

For this purpose it will be assumed that the i switch S2, Fig. 9, is closed and that the motor 22I is running. Motor 220 is standing still, as its circuit is open at contact springs 23? and 233. At contact springs 231 and 239 the resistance 23-6 is connected in place of the motor 220 and places an equivalent load on the standard frequency source.

The fuse I4 is placed in the chuck in the manner described in detail in connection with Fig. 1 and is locked in place by the cap 8. The guard 22 is then lowered to the position in which it appears in Fig. 1, thus enclosing the chuck and fuse as a protection to the operator and bringing the various parts of the optical system into operative relation to the fuse. The lowering of the guard also actuates the pin 29 and closes contact springs 21 and 28. This operation, by means of another pair of contact springs, may close a circuit for lamp 30, although the lamp may be continuously lighted while the timing operations are going on, as previousl intimated. No light from the lamp reaches the photo-cell because the light path is interrupted by the pallet arm 44 of the fuse.

The operator may now close the switch S, thereby closing a circuit for the relay I46, said cir-. cuit extending from conductor I30 by way of switch S, contacts 21 and 28, contact I42 of relay I39, and winding of relay I46 to conductor I3I. The conductors I30 and I3I are connected to a suitable alternating current supply line'and The roller 224 is tentiometer I35 to conductor I30.

relay I46 is accordingly energized, opening its contact I41 for a purpose which will be described, and at its three upper contacts connecting the motor generator set to the three phase line I62, I63, and I64 extending to the motor 2. The motor is thus started and comes rapidly up to speed,

- the period of acceleration being about two seconds or slightly less.

The motor rotates the fuse by means of the chuck in which it is held and the fuse begins to run, transmitting light impulses to the .photocell 34. The explanation of the effect of the light impulses and the operations controlled thereby willbe deferred until the further operation of the motor control circuits has been explained.

As previously mentioned, the tube I38 and associated circuits operate as a. time delay device. The plate of the tube is connected to conductor I3I by way of rela "I39. The cathode is normally open except for its connection to conductor I3I by way of resistance I31 and consequent- 1y no plate current can flow through the tube and relay I39 is normally deenergized. The grid of the tube is connected by way of resistor I32 and resistor I33 to a bridge comprising resistor I36 and potentiometer I35. At times hen the conductor I30 is positive, therefore, our nt flows over a path which may be traced from conductor I3I by way of resistance I31, cathode and grid of the tube, resistors I32 and I 33, and po- The voltage in this circuit depends on the adjustment of the potentiometer, although it will be obvious that at times when conductor I30 is positive and conductor I3I is negative any point on the potentiometer will be positive with respect to conductor I. |3II1 view of the flow of current over the above described circuit including the grid of the tube there is a fall of potential across the resistor I33 and the condenser I34 becomes charged, the polarity being such that the upper terminal of the condenser is charged negatively. The condenser cannot discharge during the half cycle periods when conductor I30 is negative and conductor I3I is positive because the tube cannot pass current from grid to cathode. A slight discharge does occur during each such period through resistance I33, but this resistance is very high and the amount of discharge is negligible. The foregoing describes the conditions when the switch S is open. When the switch S is closed, the relay I46 is energized as previousl /described. At the same time the conductor I3'II is connected to the oathode of the tube. This completes the cathode plate circuit of the tube, and current would flow during the half-cycle periods when conductor I3I is positive, except for the fact that the grid of the tube has a negative potential on it due to the charged condenser I34. The condenser can receive no further charging current now, since the cathode is connected to conductor I30, and slowly discharges through resistor I33. As the condenser discharges the negative potential on the grid is lowered gradually, and the grid eventually begins to swing positive with respect to the cathode during eachhalf-cyde period in which conductor I3I is positive. During these periods, therefore, the tube passes current and relay notwithstanding the mtermittent current which it receives.

The tube I38 introduces a delay between the closure of the switch S and the energization of relay I39. The amount of the delay is preferably about seconds, corresponding to the time required for the motor generator set to bring the motor 2 up to speed, and is regulated by adjustment of the potentiometer I35. This device adjusts the voltage to which the condenser is charged and accordingly adjusts the time required for it to discharge.

When relay I39 energizes, it breaks the circuit of relay I46 at contact I42 and closes the circuit of relay I44 at contact I M. Relay I46 accordingly deenergizes and relay I44 energizes, with the result that the motor generator set is disconnected from the motor 2 and the power amplifier is connected to the motor in place thereof. This switching operation takes place in such a manner that the motor generator set and power amplifier are not connected together;

' that is, relay I46 deenergizes an instant before relay I39 is energized. The condenser I40 is effective to produce a steady energization of the relay I44 energizes. The proper timing of the relays can be secured by adjustment, although a known form of mechanical interlock between the relay armatures can be used as an additional precaution if desired. Fusing of the leads to the power amplifier is also recommended as a safety measure to prevent any possibility of damage to the equipment.

With relay I44 in energized position the power amplifier supplies power to the motor 2 and the motor accordingly runs at a constant predetermined speed, as determined by the frequency of the amplifier output, which is accurately controlled in some suitable manner, as by a crystal oscillator. the motor runs at a speed of 16,200 R. P. M., but other speeds may have to be used for other types of fuses, and it may even be desirable to test certain fuses at different rotational speeds. The essential feature involved here is that the rotational speed is exactly predetermined and is maintained constant at the desired value.

When relay I44 energizes, it also opens its contact I45. This contact is connected in series with contact I 41 in the cathode circuit of tube I48. The tube I48 is wired up similar to tube I38 and constitutes another time delay device. Before the switch S is closed, the cathode of the tube is connected to conductor I30, the tube passes current, and relay I49 is maintained energized. The operation of switch S is followed by the energization of relay I46, which opens the circuit of the cathode of tube I48. Relay I 44 also opens this circuit, so that while the switch S is in operated position tube I48 is in non-conducting condition insofar as the cathode plate circuit is concerned and relay I49 is deenergized. At its contact I 5| relay I49 prepares a circuit for relay I52, which is held open for the time being at contact I45 of relay I44.

The fuse I4 is now being rotated at the required speed, and the clockwork mechanism therein has started to operate. The oscillations of the pallet arm permit light to pass from the lamp 30 by way of the reflecting surface 43 in the fuse (see Fig. 3), and the annular mirror 36, to the cathode I00 of the photo-cell, .but the light is interrupted during each beat of the pallet arm as it passes through its mid-position. The photo-cell thus receives light interrupted at the beat frequency of the fuse, which in this case is assumed to be 344 beats per second, and

In the case being described" these other components are relatively small as compared to the 344 cycle component.

The photo-cell circuit extends from ground by way of the cathode I00, anode IOI, resistance I02 and resistance I05 to the conductor I03,

which connects to the +13 lead 260, Fig. 9. 4

Variations in the current in this circuit produce changes in potential at the anode I III, which are transmitted to the grid of tube IIO by means of the condenser I03. The tube IIO functions as an amplifier and its output, including a principal component having a frequency of 344 cycles per second, is further amplified by the tube III. The operation of these tubes is well known and need not be described in detail.

The coupling circuit between tubes III and I includes a filter network comprising the inductance H4 and condenser II5, which is tuned to resonance at a frequency of 344 cycles ,per second. The voltage impressed on the grid of tube I20 depends on the impedance of this filter network, which is very high at a frequency of 344 cycles per second and comparatively low at higher and lower frequencies. The 344 cycle component of the output of tube III therefore produces relatively large voltage changes at the grid of tube I20, whereas other components produce little effect. and are substantially eliminated.

The output of tube I20, which also functions as an amplifier, would be adequate without further amplification, but the voltage of the output is subject to variations in amplitude due to differences in the fuses and other causes, and accordingly the voltage regulator tube I23 is provided. The output circuit of tube I20 is coupled to the grid of tube I23 through the highresistance I22, having a value of about ten megohms. This resistance is so high, as compared to the cathode to grid resistance of the tube, that the potential on the grid can never become more than slightly positive with respect to thecathode. The plate current at tube I23 therefore changes between zero and a small value, regardless of the amplitude of thecontrol voltages applied to the grid from the output circuit of tube I20, and the output of tube I23 has a fiat topped wave shape of substantially constant amplitude.

The output of the voltage regulator tube I23 is applied to the grid of tube I25, which functions as an amplifier and makes up for the losses at tube I23. Tube I25 therefore supplies a reliable signal derived from the rotating fuse,

having a frequency of 344 cycles per second and vibrator is known and hence need not be described in detail. It will sufllce to say that the first multivibrator 200 is controlled-over conductor I20 and oscillates at a frequency of 172 cycles per second, thus dividing the 344-cycle signal frequency by 2. The second multivibntor 20l is controlled from the first, and oscillates at a frequency of 57% cycles per second, dividing by 3. The third multivibrator 232 divides by 3 also and oscillates at a frequency of 19% cycles per second. The fourth multivibrator 2 divides by 2 and oscillates at a frequency of 975 cycles per second, which is the output frequency of the frequency divider. Considered as a whole, the frequency divider divides by 36; that is, the output frequency is ,5 that of the original signal current generated by the photocell in response to operation of the fuse.

It will be understood that the fuse signal current, referred to herein as having a frequency of 344 cycles per second, has exactly that frequency only if the particular fuse from which the current is generated is running at exactly the proper rate. If the rate is incorrect, the frequency of the signal current will not be exactly 344 cycles per second and the frequency of the output from the frequency divider will vary accordingly. This output frequency is compared with a standard frequency by the recording device in order to determine if the rate of the fuse is correct, or is fast or slow.

The output of the frequency divider has a suitable frequency for controlling the recording device, but otherwise is entirely unsuitable and has to be converted into a train of short direct current impulses having the same frequency. It is for this purpose that the tube 2" is provided. The last stage multivibrator is connected by way of condenser 20! and resistor 205 to the grid of tube 206, whereby control voltages may be applied to the grid. Tube 206 is normally inoperative, however, because the grid is grounded at contact 255 of relay 253.

Tube 200 is rendered operatlve by opening of the ground connection to its grid at the time the motor 2 is switched over to the power amplifier. At this time the fuse will be operating and control voltages will be delivered over the conductor I21 to the grid of tube 250. This tube functions as an amplifier and has its output circuit coupled t the grid of tube 25I, which also functions as an amplifier. tube 25I includes the relay 253 and is closed at contact I43 of relay I39 when the latter relay operates. Relay 253 is accordingly energized at the same time as relay I. To prevent chattering of relay 253 its winding is shunted by a condenser. The proper operation of tubes 250 v and 25I is secured by adjustment of the potentiitive with respect to the grid, which is normally a relatively constant amplitude. I

The output of tube I25 is used to control the first stage multivibrator 200 of the frequency divider, Fig. 9. The frequency divider is provided for the purpose of reducing the frequency of the signal generated by operation of the fuse to a lower frequency which is suitable for operating the recording device. The operation of a multioutput from the frequencydivider.

at ground potential, and insures a positive release of relay 253 when signal current ceases.

When relay 253 energizes, contact 255 is opened and tube 206 is placed under the control of the Tube 203 has two control grids. The upper grid is main- The plate circuit of of a potentiometer consisting of resistors 201 and 208. The potential on the lower grid, is determined by the control voltage received from the frequency divider. The output of the frequency divider has a wave shape characteristic of multivibrators; that is, the negative half-waves are of considerable amplitude and have a steep 'wave front. Each negative half-wave therefore drives the lower grid to a potential which is considerably below ground potential and far enough below'the potential on the upper grid so that the difierence in grid potentials is sufficient to start th discharge of the tube.

When the tube 206 becomes conductive in the manner explained above, the condenser 2I0 discharges quickly over a-path which includes the cathode and plate of the tube and the printer bar operating magnet 23I, thus furnishing a short, powerful energizing impulse to the magnet, the condenser 2I0 having sufficient capacity for the purpose. The discharge of the condenser reduces the voltage at the plate of tube 206 to such a low value that the discharge through the tube cannot be maintained and it becomes non-conductive. The condenser 2I0 now charges up in series with the resistor 2I I, the value of the resistor being such that the condenser becomes nearly fully charged by the time the next negative half-wave of control voltage appears at the lower grid of tube 206. The tube 206 then becomes conductive again and the condenser 2I0 is again discharged through the magnet 23I. The operation of tube 206 continues in this manner as long as the control voltages are supplied from the frequency divider.

From the foregoing it will be seen that the frequency divider output, having a frequency of 954, cycles per second, is converted by means of the tube 206 into a train of direct current impulses having the same frequency, which are effective to actuate the printer bar magnet 23I. These operations of the magnet result in the printing of a record of the operationof the fuse, as will now be explained.

When relay 253 energizes, it also closes a circuit for magnet 232 at contact 256. Magnet 232 accordingly energizes and by means of its armature 226 presses the roller 225 against the tape 230 at the point where the tape passes the roller 224. Armature 226 also actuates the contact spring 231, which disconnects the load resistance 236 and connects the motor 220 in place thereof. The motor 220 now starts to run and rotates the roller 224, which begins to feed the tape 230 along past the edge of the rotating toothed disk 235. The recording device is now in operation. Each time the printer bar 234 is depressed by the energization of magnet 23I, it cooperates with a tooth of the rotating disk 235 to print a mark on the tape 230, and these marks are spaced apart in a row due to the linear feed of the tape past the edge of the disk.

The speed of the motor 22I is constant and has such a value that an exactly even number of teeth will pass the tape 230 between successive actuations of the printer bar, provided the fuse being timed is running at the correct rate. The tooth speed may be, for example, 172 teeth per second. There may be 12 teeth on the disk, in which case the motor 22I will run at a speed of 860R. P. M. The output frequency of the standard frequency source is such that the motor is run at the correct speed.

The number of teeth which pass the tape between successive actuations of the printer bar,

I another fuse is inserted.

with the above assumed tooth speed of 172 teeth per second, is 18. This follows from the fact that the signal frequency is 36 times the printer bar frequency and from the further fact that the assumed tooth speed is one-half the signal frequency.

The direction of the row of marks which is printed on the tape indicates to the operator whether the rate of the fuse is correct or not, and if the rate is incorrect, whether it is fast or slow. If the rate is correct, the teeth of disk 235 which are used on successive printing operations will be in exactly the same transverse position relative to the tape when the printing operations take place, and the resulting row of marks will be parallel to the edge of the tape. If the rate of the fuse is slow, the disk 235 will gain a little between successive printing operations and assuming clockwise rotation of the disk as viewed from the front, the row of marks will trend to the right. Similarly, if the rate of the fuse is fast, the disk 235 will gradually fall behind, and the row of marks will trend to the left. In either case the sharpness of the trend, or the size of the angle which the row of marks makes with the edge of the tape, is a measure of the amount of error in the rate.

Since the marks are printed at the rate of 9% marks per second, it will be clear that in two or three seconds enough marks will have been printed so that the operator can determine the direction of the rowf The operator then stops the timing operation by releasingthe switch S.

Upon the opening of the switch, the time delay device including tube I38 reverts to its normal condition, tube I38 ceases to pass current, and relay I39 is deenergized. The deenergization of relay I39 opens the circuit of relay I44, which deenergizes also and disconnects the power amplifier from the motor 2. Relays I44, I46, and I49 now being in deenergized condition, a circuit is completed for relay I52, which energizes and at its contacts I53 and I54 connects a source of direct current to the power leads I63 and I 64 extending to the motor. This operation brings the motor quickly to a stop. The closure of contact I45 of relay I44 not only completes the circuit of the braking relay I49 as described, but also connects conductor I30 to the cathode of the tube I 48. This tube operates in the same way as was described in the case of tube I38 and after several seconds, therefore, it begins to pass current and relay I49 is energized. The circuit of relay I52 is thus broken at contact I5I and relay I52 deenergizes, disconnecting the direct current source from the motor. The time delay device including tube I48 should be so adjusted that the braking current is applied to the motor for a period of time just sufficient to stop the motor reliably.

The operator now raises the guard 22 to expose the fuse and chuck. Further operations depend on whether the rate of the fuse just timed is correct or not. If the rate was found to be correct, the fuse is removed from the chuck and It may be assumed, however, that the fuse was found to be slow, as indicated by a row of marks 246, which trends rapidly to the right.

The operator therefore makes an adjustment of the fuse such as to make the clockwork mechanism run at a faster rate. The adjustment having been completed, the operator lowers the guard and then depresses the switch S to start recording device.

another timing operation. It will be noted that the operation of the switch while the guard is up will have no effect, since the contacts 21 and 28 must be closed also before the timing operation can be started.

It may be assumed that on the second timing operation performed on this particular fuse a row of marks such as shown at 241 is printed. This row trends to the left slightly, indicating to the operator that the adjustment was carried too far, causing the fuse to run slightly fast. Another adjustment and timing operation is therefore required. It may be assumed that the next time the fuse is tested its rate is found to be correct, as indicated by the row of marks at 8, which is parallel to the edge of the tape.

The switch SI, Fig. 9, is adapted to close a circuit to an oscillograph which may be provided for the purpose of indicating the rate of fuses occasionally met with, which are so far oif'in rate that they cannot be timed to advantage with the The operation of an oscillograph for this purpose is known and hence will not be described.

It will be seen from all the foregoing that a new and improved timing apparatus has been devised which is particularly well adapted for timing fuses of the type described herein while the same are undergoing rotation at high speed. The utility of the apparatus is not necessarily limited to the timing of fuses, however, as it may be used in any situation where the rate of an oscillating member is to be determined while it is rotating, suitable modifications being made if necessary to adapt the apparatus to the circumstances of each case. It will be understood also that, whereas certain specific apparatus and circuits have been described herein, this has been done merely for the purpose of acquainting the public with a method of practicing the invention and not with the intention of limiting the invention to any particular embodiment thereof. I do not therefore wish to be restricted to the precise form of the invention which is shown and described herein, but desire to include and have protected by Letters Patent all forms and modifications of the invention that come within the scope of the appended claims.

I claim:

1. Apparatus for timing a fuse of the clockwork type having a part subject to oscillatory motion, comprising means for rotating said fuse, a light source, a photocell, means including a mirror whereby said photocell is placed under the control of said light source over a light path which rotates in synchronism with said fuse and which is periodically interrupted by said part while oscillating, means including said photocell for generating periodic voltages having a frequency bearing a predetermined relation to the oscillatory frequency of said part, and means for comparing the voltage frequency with a standard frequency.

2. Apparatus for timing a device having an oscillating member while the device is in rotation, comprising means for projecting a beam of light across the path of said oscillating member, said beam intersecting said path at a point outside the axis on which said device is rotating, means for rotating said beam in synchronism with said device and about the same axis so that the relation between the beam and the oscillating member will be unaffected by rotation of said device, a photocell for receiving said beam when the same is not intercepted by said member,

meansincludingsaid photocell for generating periodic voltages having a frequency bearing a predetermined relation to the frequency of said member, and means for comparing the voltage frequency with a standard frequency.

3. Apparatus for timing a device having a part subject to independent periodic .lnotion while the device as a whole is subjected to rotation, comprising means for rotating said device, means for projecting a beam of light along a path which rotates in synchronism with said device and which is so arranged that the beam isthe device as a whole is being rotated, comprising means for rotating said device, including a chuck for holding thev device while it is rotating, a photocell, means including a mirror for passing a beam of light through said chunk and device tosaid photocell along a line which rotates in synchronism with said device and which is periodically cut by said part while oscillating, means including said photocell for generating periodic voltages having a frequency bearing a predetermined relation to the frequency of said oscillatory motion, and means for comparing the voltage frequency with a standard frequency.

5. Apparatus for timing a fuse of the clockwork type having a part subject to oscillatory motion, comprising means for rotating said fuse, a light source, a photocell, a means including an annular mirror surrounding said fuse and cooperating with a reflecting surface of said fuse for placing said photocell under the control of said light source over a rotating light path which is periodically intercepted by said part while oscillating, means including said photocell for generating periodic voltages having a frequency bearing a predetermined relation to the frequency of said oscillatory motion, and means for comparing the voltage frequency with a standard frequency.

6. Apparatus for timing a device having an oscillating member while the device is rotating, comprising means for projecting a beam of light along a line which coincides in part with the axis of rotation of said device and which includes a section which is non-coincident with said axis and crosses the path of said oscillating member, means for rotating said beam about said axis and in synchronism with said device, a photocell on which the beam impinges when not intercepted by said member, means including said photocell for generating periodic voltages having a frequency bearing a predetermined relation to the oscillating frequency of said member, and means for comparing the voltage frequency with a standard frequency.

7. In a fuse timing apparatus, a chuck for holding a fuse, a motor for rotating said chuck, a passageway for light extending through the motor shaft and across the path of an oscillating part of a fuse held in the chuck, a source of non-parallel light rays for continuously directing light along said passageway, a photocell on which light coming through said passageway impinges. means including said photocell for generating periodic voltages having a fre-- quency bearing a predetermined relation to the frequency of said oscillating (part, and means for comparing said voltage frequency with a standard frequency.

8. Apparatus for timing a fuse having a part subject to oscillatory motion, comprising a chuck for holding said fuse, a motor having a hollow shaft for rotating said chuck, a source of light and a' photocell located on the rotation axis and on opposite sides of the chuck and motor assembly, means for passing a beam of light from said source through the motor shaft, chuck, and fuse to said photocell along a, line which departs from the rotation axis to cross the path of said oscillating part, and electrical means controlled by said photocell for comparing the frequency of said oscillatory motion with a standard frequency.

9. In a fuse timing apparatus, a rotatable chuck comprising means for holding a fuse, a light source, a photocell, means including a. mirror effective while a fuse is being rotated by said chuck whereby said photocell views said light source over a path having a section which rotates with said fuse and which is periodically interrupted by an oscillating part of said fuse, and means including said photocell for generating periodic voltages responsive to the interruption of said light path.

10. In a fuse timing apparatus, a rotatable chuck for holding a fuse, means cooperating with a reflecting surface of a fuse being rotated by said chuck for forming a radial beam of light passing through an opening in the side of said chuck, said light being periodically interrupted by a moving part of the fuse, a photocell, and an annular mirror surrounding said chuck for reflecting said light beam to said photocell.

11. In a fuse timing apparatus, a rotatable chuck for holding a fuse, a photocell positioned on the rotation axis of the fuse, a lamp located on said axis between the photocell and the fuse, means including a light passage extending through the fuse and a mirror for passing a beam of light from said lamp to said photocell, and transparent suporting means for said lamp to permit passage of said beam.

12. In a fuse timing apparatus, a rotatable chuck for holding a fuse, said chuck having a passageway for light which coincides in part with a light passage extending through a fuse which is held in the chuck, a removable protective guard adapted to enclose the chuck and fuse, and an optical system including a lamp and a photocell mounted on the inside of said guard and also including a path for light extending from said lamp through said passageway to the photocell when the guard is in protective posi tion with respect to said chuck and fuse.

13. In a fuse timing apparatus, a chuck for holding a fuse, means for rotating said chuck, a source of light, a mirror system in said chuck for receiving light from said source and for directing it over a path which crosses the plane of oscillation of an oscillating member in said fuse and leaves the chuck along its axis of rotation, and a photocell located on said axis for intercepting light which is transmitted over said path and not intercepted by said oscillating member.

14. In a fuse timing apparatus, means including a chuck and a motor for rotating a fuse, a protective guard adapted to enclose said chuck and fuse while the same are rotating, photoelectric means in said guard for generating periodic voltages responsive to operation of 'said fuse, means also contained in said guard for amplifying said periodic, voltages, and a partition dividing the interior of said guard into two compartments, one compartment containing the said chuck, fuse, andphotoelectric means and the other compartment containing the said amplif ing means.

15. In a fuse timing apparatus, means including a chuck and a motor for rotating a fuse, a protective guard adapted to enclose said chuck and fuse while the same are rotating, means including a photocell inside said guard for generating periodic voltages responsive to operation of said fuse, means including a space discharge device inside said guard for amplifying said voltages, an amplifier outside said guard including a second space discharge device, and asingle conductor extending between the guard and said amplifier for supplying anode potentials to said photocell and said first discharge device and amplified control voltages to the grid of said second space discharge device.

1 16. Apparatus for use in testing a device which includes a part having an orbital motion and a periodic oscillatory motion, comprising a light path including a section rotating in the orbit of said part in phase therewith and at the same speed, whereby said light path is periodically modified by the oscillatory motion of said part, means for transmitting light over said path, a photocell on which the light transmitted over said path impinges, and means including said photocell for generating periodic voltages having a frequency dependent upon the frequency of said oscillatory motion. I

17. In a fuse timing apparatus, means for rotating a fuse, a photocell located on the rotational axis of said fuse, a light source also located on said rotational axis, said fuse including means cooperating with said light source to transmit a modulated light beam in a direction at an angle to the rotational axis of the fuse, and means including an annular mirror for intercepting said beam in all positions which the fuse assumes while rotating and for reflecting the intercepted beam to said photocell.

18. In a fuse timing apparatus, a rotatable chuck for holding a fuse, an annular mirror surrounding sald chuck, means for projecting light to said mirror over a path which is adapted to be influenced by operation of the fuse responsive to rotation thereof by said chuck, and a photocell to which the said mirror reflects the light received over said light path.

19. In a fuse timing apparatus, an optical system including a light source and an annular mirror, a chuck for supporting a fuse on the axis of said mirror, means for rotating said chuck to cause the fuse to transmit a rotating beam of light from said source to said mirror, said beam being periodically influenced by operation of the fuse while undergoing rotation, and a photocell to which the said beam is reflected by said mirror in all angular positions of said fuse.

20. For use in timing mechanical fuses, a rotatable chuck comprising two manually separable parts, of which one part includes a seat for a fuse and the other part includes means for clamping the fuse in said seat, said chuck also including reflectors mounted on said parts and included in an optical system for directing a beam directing a beam of light through said shaft and chuck, and reflecting means in said chuck for displacing a section of said beam so as to cross the path of a movable member forming part of a device held in said chuck.

22. For use in timing mechanical fuses, a rotatable chuck comprising means for holding a fuse which has a light passage adapted to be interrupted by an oscillating part of the fuse, an opening in the side of said chuck for the passage of light, and means included in the chuck to aid in orienting a fuse inserted therein so that the said light passage is aligned with said open .ing.

23. For use in testing mechanical fuses, a ro tatable chuck comprising means for holding a fuse, said fuse being of the type which includes means for projecting a light beam at an angle to the rotational axis of the chuck when the fuse is held therein, said light beam being under the influence of a moving part of the fuse, an opening in the chuck for passage of said beam, and means for preventing seating of the fuse in the chuck unless the fuse is so oriented that the said light beam can pass through said opening.

24. For use in testing mechanical fuses, a rotatable chuck comprising means for holding a fuse, said fuse having a light passage adapted to be influenced by a moving part of the fuse, said chuck also having a light passage including openings for the entrance and egress of light, and means in said chuck cooperating with said fuse to aid in orienting the same when inserted in the chuck so that the two light passages supplement each other to form a continuous light passage.

25. For use in testing mechanical fuses, a rotatable chuck including a seat for a fuse, means for holding the fuse in said seat, a light passage controlled by a moving part of the fuse when the fuse is operating and adapted to be completed only when the fuse occupies a particular angular position in said seat, and means in said chuck to aid in orienting the fuse to said position when it is placed in said seat.

26. For use in testing mechanical fuses, a rotatable chuck comprising a base member, a hollow cap member, means for locking the cap member to the base member, oppositely disposed seats for a fuse located in said base and cap members, respectively, one of said seats being movable, and resilient means for urging the movable seat in the direction of the other seat.

27. For use in testing mechanical fuses, a rotatable chuck comprising a base member having a seat for a fuse, a removable cylindrical cap member adapted for telescopic cooperation with said base member to enclose a fuse seated thereon, a second seat for the fuse carried by said cap member and adapted to engage the fuse when the cap member is placed on said base member, means permitting one of said seats to yield when the cap member and base member are telescoped together, and means for securing the cap member to the base member.

28. In a fuse timing apparatus, a rotatable chuck comprising means for holding a fuse, said chuck and the fuse which is held therein having a passageway for light which rotates with the fuse and which is periodically interrupted by a moving part of the fuse when the chuck is rotating, a photocell, means incluing a mirror for directing light through said passageway to said photocell with the chuck in any angular position, and means including said photocell for generating periodic voltages responsive to the periodic interruption of said light passageby the said moving part of the fuse.

THOMAS B. GIBBS.

Images