US1509899A - Stop-watch mechanism - Google Patents

Description

Sept. 30, 1924. v 1,509,899

D. W. MANN STOP WATCH MECHANISM 3 Sheets-Sheet 1 a 1/ w biifj.

wminm Sept. 30 1924.

D. W. MANN STOP WATCH MECHANISM Filed March 26. 1921 3 Sheets-She 2 Sept. 30, 1924. 1,509,899

D. w. MANN STOP WATCH MECHANISM Filed larch 26. 192 3 heets-Sheet 3 tion.

Patented Sept. 30, 1924.

UNITED STATES DAVID w. MANN, or LINCOLN, MASSACHUSETTS.

STOP-WATCH MECHANISM.

Application filed March 26, 1921. Serial No. 455,805.

To all whom it may concern:

Be it known that I, DAVID W. MANN, of Lincoln, in the county of Middlesex and State of Massachusetts, a citizen of the United States, have invented a new and useful Improvement in Stop-Watch Mechanisin, of which the following is a specifica- My invention is an improvement in mechanism useful in stop watches or the like, and relates more particularly to the escapement. In watches of ordinary construction the escapement is controlled by the oscillation of a balance wheel governed by a fiat spiral spring called usually the hairspring. The second hand of a watch, therefore, moves over its dial bysmall jumps whose period is that of an oscillation in one direction of a balance wheel, which usually occupies one fifth of a second, and the watch can only be stopped at such intervals. Any attempt to increase this rate of vibration above five per second and so increase the accuracy of the stop watch in timing is rendered difficult, if not almost impossible, because of the friction of pivots, etc.

The purpose of my invention is to make an escapement which is adapted particularly for use where it is desired to measure short intervals of time with more accuracy than is possible by means of an ordinary stop watch, and for" this purpose I provide a vibratory member which is suitably connected with the escapement and is of such character that rates of vibration of 24 per second or even higher have been secured.

My invention will be understood by reference to the drawings in which it is shown in its preferred form, together with a portion of the usual works of a watch or clock showing how my embodiment is connected thereto so as to control the watch movement. These parts being of usual construction are not described except so far as may be necessary to explain my invention. In the drawings the parts are very much enlarged.

Figure 1 is a front view of a stop watch movement embodying my invention showing the mechanism at rest, a portion of the face being broken away.

Fig. 2 is a similar view, enlarged, showing the mechanism in operative position.

Fig. 3 is a similar view showing a portion of the mechanism after it has been stopped, but before it has been reset or brought to the position shown in Fig. 1.

Fig. 4 is a side view taken from the left side of Fig. 3.

Fig. 5 is a section on line 55 of Fig. 3 showing the vibratory member in plan.

Figs. 6 and 7 are sections on lines 6-6 and 7-7, respectively, of Fig. 5. I

Fig. 8 is an enlarged sectional detail illustrating the hand-setting mechanism.

Fig. 9 is a modification of the hand-setting control.

1 is a cylindrical case comprising base plate 2 and having a threaded opening 3. 4 is a neck through which projects the usual winding arbor 5. 6 is the second or measuring hand mounted in the usual way on a central arbor 7 to be moved over the clock face 8 and to be returned to a zero mark. The clock face may be divided into units of any desired character. The arbor 7 carrying the hand is rotated by mechanism well known to clock makers, and hence need not be described. Such mechanism comprises the usual spring which is wound by means of the arbor 5 and the usual mechanism operated thereby.

9 is the escapement wheel of usual form operated from the main spring in the usual way. 10 is the escapement lever by which the escapement wheel is alternately released and stopped so that it allows a step-by-step movement to be imparted to the hand 6. The escapement lever 10 is mounted on an axis 11, the upper bearing for which is part of the top face plate 13. The lower end of the axis 11 sets into a hanger 131 in the form of an arm attached to the under side of plate 13. The base 2 has attached to it a block 15 having a neck 16. The vibratory member 14, which takes the place of the ordinary pendulum mechanism, consists of a plate having a rectangular opening 17 of sufiicient width to receive the neck 16,

which projects through it. The vibratory member 14 is attached to the neck 16 by means of a leaf-spring 18 one end of which is attached to the clock by means of a plate 21 and screws 19, while the other end of the spring is attached to the vibratory member by a plate 22' and screws 20, this arrangement being such that the vibratory member is supported from the spring at its centre of gravity.

The vibratory member 14 carries two supports 23, 24 from each of which projects a screw 25 carrying threaded weights 26 by which the timing of the member 14 may be adjusted. It also carries two pins 2*? and 28, the pin 28 being preferably mounted on support 2- 1. @ne of these pins 27 engages the notched end of a sprin impulse lever 29., which is mounted on the axis 11 so that it and the escapement lever will move together.

it is desirable for accurate timing that the impulse lever should be a spring because it permits varying amplitudesoi the vibratory member above the i'i'iinimum angle required to unlock the escapeinent and so permits the vibratory member to take up its natural period of vibration with out substantial restraint from the escapement.

The lever 29 lies parallel with the vibratory member acting as the operative connection between the escaoeinent lever 10 and the vibratory member 14. The pin 28 which is mounted on the support 2 forms one member-o f a stop n'iechanisin the other member of which is a lev 3O pivoted at 31 on top of the plate 13. This lever is of angular shape and has toe 82 at its end to engage the pin 28 and a heel 33 which when the mechanism is at rest engages one off a series of projections on the upper surface of a ratchet wheel mounted on an arbor 3-43; in the plate 13. The ratchet is operated by a pawl 36. Thepawl 36 is mounted on the end of a pin 37 carrier. by an armature 38 pivoted at 3 9 to a si'iitable Frame and operated by means of an electromagnet 40. The plate 13 is slotted as at 41 0 allow the mechanism which operates the )awl 36 to be moved by the armature to lo its work. Thus when the electromagne" is energized. the ratchet wil one tooth. The projections 3 l are mounted about the face 01 the ratche to form slots or recesses, these slots 1' i every third tooth oi the rat Let each third movement of the ratchet oy pawl 36 the heel 3-3 of the lever pulled into the registering slo spring 332 one end of which is attac ied to the lever 30 and the other to the 13. Normally the heel rests agains; edge of one of the projections iime the toe ei gages the pin holds the vibratory member statior igure 1 shows the mechanism at rest and l 2 shows these parts in oaerative position, the vibratory member being actuated brough the escapcment. ll hen the parts are in the position shown in Fig. l the vilu'atoi'y member is held against motion by means of the contact between the toe 32 and the pin 28. T11 Fig. 2 where the electro magnethas been energized and has caused the pawl to turn the ratchet one tooth and the heel has been pulled into the slot bei i n two of the projections 381 by means 0i its controlling spring 332, the toe of the lever 30 has been moved a vay from the pin 28 so that the vibratory member is free to vibrate. At the next movement of the ratchet by the pawl 36 one of the projections 221 pushes under the h el of the lever 30 so that the heel rests upon it as in Fig. 3.

The projections 3-31 on the ratchet 35 serve also to operate the hand-setting lever 42. This lever is pivoted at i land is con trolled by a spring 413 which tends to pull its outer pointed end 45' against the heartshaped cam 46 on the arbor 'i' carrying the hand 6, the cam and the hand being arranged in predetermined position and held together preferably described as below so that when the parts are in the position shown in Fig. l the hand points to zero. lt will be see from 2 that the hand has been moved away from zero and the setting member has been carried with it. The stop ping of the clock is due to the second impulse of the electromagnet by which the ratchet is again pushed one tooth and the lever 30 rides again aga' st the projection 331 on the ratchet thus bringing the toe 32 of the ever 30 into engagement again with the pin 2 The lever 4-2 is operated in the same way. l't has a linger 461 which its spring holds against the )eriphery of the projections 331 on the ratchet and the first movement of the pawl which sets the parts in operation by moving the ratchet, throws the finger on the lever 42 out from its normal position between two 01" the projections 33]. onto the top of one of these projections. here the leversetsas shown in Figs. 2 and 0 while the clock is in operation aid until after the movement of the ratchet which the clock. The energizing of the elec trom gnet for a third time causes the ratchet to turn so that the falls between the projections on the ratchet and the end 4-5 of the lever strikes the heart-shaped member 46 and noves it until the point of the lever 4:2 falls into the recess in the setting member at which time the hand will pointto zero. is a spring pawl to restrain the movement 01 the ratchet.

l prefer to provide means now to be (e scribed "for causing; the cam 46 and the h nd 6 to rotate with the arbor without slipping; when the watch is in us For this para s: l have provided mechanism which will be understood from Fig. 8. Thehand (5 is mounted on a sleeve 160 on the shaft 7 and wider a washer 700 held in place on the shaft by a pin 701. The settingcam 16 is also mounted on the sleeve 4:60 in the usual way. Instead of the light spring usually employed in devices of this sort for causing the sleeve carrying the hand to rotate with t e shaft, a clutch Tl is provided which is held in contact with the sleeve 460 by a spring 72 which by pressing at its lower extremity on a washer 73 pushes the clutch 71 against the sleeve 460 with sufiicient pressure as to cause it to rotate with the shaft 7 without slipping.

To reset the hand when the clock is stopped a lever 74 is pivoted at 7 5 on the plate 13. One end is forked to ride over the pin 76 on the under side of lever 42. The lever 74 carries a wedge piece 77 shaped to engage a corresponding wedge or conical surface on the upper side of the clutch 71, this arrangement being such that as the setting lever 42 is moved into engagement with the setting member or cam 46, the wedge piece 77 is moved into engagement with the clutch 71 and depresses it against the spring 72 so as to release the setting member and hand, thus allowing the setting member and the sleeve 461 carrying the hand 6, which comes in contact with it, to move together when struck by the end of the lever 42.

While the arrangement of the spring 43 is for controlling the lever 42, under ordinary circumstances I prefer the construction shown in Fig. 9 where the spring 43 connects the lever 42 with one arm of a bell crank lever 431 pivoted at 432 on the plate 13. The bell crank has a pin 433 at the endof its other arm which engages the holding pawl 471 which differs from the holding pawl 47 in the other views by being mounted on a very thin piece of metal of sufiicient strength only to support it. In Fig. 1, etc., it will be seen that the effort required of the electromagnet in starting the clock is greater than that required in stopping it or in setting it back to the zero point, this condition being caused by the fact that more power is required to lift the projection 461 on lever 42 from between the projections 331 on ratchet wheel 35 than is required when the projection 461 rides on the projections 331. From Fig. 9 it will be seen that these differences in effort are equalized by the varying pressure of pin 433 against the pawl 471, these differences in pressure being caused by the action of the spring 43 against the end of the bell crank lever 431.

The operation of the device will be understood it is believed from the above description. In the circuit of the electromagnet is a circuit closer adapted to close the circuit momentarily to attract the armature and operate the ratchet 35. Upon the position of the ratchet 35 depends the operation of the stop watch. Energizing'the electromagnet 40 attracts its armature 38 which causes the pawl 36 to move the ratchet 35 one tooth. If the parts are in their normal stopped position as shown in Fig. 1 an electrical impulse in the electromagnet causes the pawl 36 to move its ratchet 35 one tooth which brings one of the slots between theprojections 331 in register with the heel 33 of the lever 30 so that the heel will be drawn into the slots by the spring 332 thus separating the toe 32 and the pin 28, and allowing the escapement to operate the vibrator. This situation continues until the next impulse is given to the armature to move the ratchet another tooth which causes the heel 33 of the lever 30 to be pushed out of the slot so that it rests against one ed e of the next projection and its toe is pushed against the pin 28 and stops the movement of the vibrator and the watch. The next impulse of the armature pushes the ratchet another tooth so that it passes in contact with the heel 33 until the parts come again into the position shown in Fig. 1 ready to have this cycle of opera tion repeated.

During this time the projections on the other side of the ratchet are performing similar operations in connection with hand-setting mechanism. The finger 461 on the lever 42 in this case normally lies in one of the slots between the projections 331. At the first movement of the ratchet the finger 461 is thrown out of the slot and rests against an adjacent projection during the movement of the ratchet. At the third movement of the ratchet the lever 42 is reset and is in position to reset the hand 6 to zero because of its bearing on the heart-shaped member 45. The lever 42 also operates the hand clutch 71 as above described at the same time. The novelty of its construction and operation is due mainly to the construction and operation of the vibratory member which, because of the spring connection between the vibratory member and its support, does away with pivots and other devices which might produce friction, and thus allows an increase in the rate of vibration of the vibratory member which permits of very accurate measurement of short intervals of time.

I prefer to use a flat or leaf spring as part of the mounting for the vibratory member as it lends itself particularly well to they purpose. Other embodiments of my invention will occur to those skilled in the art What I claim as my invention is 1. In an escapement mechanism, a stationary member, a. spring mounted thereon, a vibratory member mounted between its ends on said spring, an escapement lever, and means connecting said escapement lever and said vibratory member whereby said vibratory member will be vibrated.

21 In an escapement mechanism, a stationary member, a spring mounted thereon, a

vibratory member mounted on said spring, I

a flexible escapement lever, and means connecting said flexible escapement lever and 1011 211? mem it comprising a vibratory member and a stationary attached to em escapoment lever and connections lJQ'JWGGlI said e capenient and 1 said worst 2351 m mber whereby said vibratory member will be vibrated.

5. ln an escap men-5 mechanism a stationary member, a li. spring mounted. tl ereon, a vibratory member mounted between its ends on said leai spring, and means for operating sad vibr ory membe 6. In an eseapemer t niechai ary nember, a leai s pring mount a vibntory member mounted ends on said leaf sprinv and operating said j a vibratory member providec jnstable means whereby the timing of its vibrations may be adjusted.

7. in an escapement meoln .i 1 ary member, a leaf sln'inn mounted enereon, a vibratory member monnted on said leaf spring, and means for operating said vibratory member, in combination with a stop rsoaeee mechanism comprising a springeontrolled lever, normally restraining said vibratory member from movement, and means for disengaging said stop lever irom said vibratory member, said stop lever having a projection and said last-named means comprising a ratchet having separated projections, each adapted to engage the projection on said lever and means for turning said ratchet,

whereby the projection on said stop lever H l r in spring between tie projections on c 1g an electron'iagnet, a

a i i be operated thereby and bearing projections on its face, said spring-controile being shaped to move between said projections or against them according to the relative location of said projections and said lever.

DAVID W. MANN.

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