US2562635A - Escapement mechanism - Google Patents

Description

J y 1951 G. E. NICHOLSON ET AL 2,562,635

ESCAPEMENT MECHANISM Filed 001;. 16, 1944 END OF RESET FIG-3.4-

IMPuLsE COMPLETED F16. 3

IMPULSE FIGZ DEAD BEAT FIG. I

INVENTORS a. 5 N/CHOL so/v BY J. a. MC GAY Patented July 31, 1951 ESCAPEMENT MECHANISM George E. Nicholson and John B. McGay, Tulsa, Okla., assignors to Precision Products, Inc., Tulsa, Okla., a corporation of Oklahoma Application October 16, 1944, Serial No. 558,894

1 Claim. E

rotation.

Another object of this invention is to provide an escapement mechanism for accurately governing a timer movement which is transmitting an excessively high power which can be utilized for other purposes and still not cause over-banking of the balance wheel in the escapement mechanism.

And still another object of this invention is to provide an escapement mechanism of the above nature wherein there is a simple self-starting arrangement that eliminates all friction or drag against the balance staff of the mechanism.

A further object of this invention is to provide an escapement mechanism which is simple in construction, inexpensive in manufacture, eflicient and durable in use.

With these and other objects in view there has been illustrated on the accompanying drawing, one form in which the invention may be conveniently embodied in practice.

Fig. 1 is an enlarged plan in showing the escapement mechanism in dead beat position.

Fig. 2 is a similar view showing the mechanism in impulse position.

Fig. 3 is a similar view to Fig. 1 showing with the impulse completed.

Fig. 4 is also a similar view showing the mechanism at the end of its reset position.

Fig. 5 is an enlarged fragmentary sectional elevational view of the escapement mechanism.

Referring to the drawing in detail wherein like reference characters denote corresponding parts throughout the various views, the numeral l0 indicates a balance wheel rigidly mounted on a shaft l2 floatingly disposed in bearings l4 and 16 secured in spaced clock plates l8 and 26. As disclosed in Fig. 5, a stud 22 is secured in plate I 8 and is provided with a hair spring 24 connected to the balance wheel shaft l2. It is to be noted that the shaft 12 has a cutaway portion 26 for cooperating with the escapement lever which will hereinafter be referred to. An escapament lever 28 is pivoted on a shaft 3!! fixed between the plates l8 and 20. An escapement wheel 32 is fixed to a main shaft 34 in turn fixed between the plates l8 and 20. The escapement wheel is provided with a plurality of peripheral teeth 36, each of which is constructed so as to provide straight flat face 38 and an angular face 40.

The escapement lever 28 is provided with a substantially circular central portion 42 having extending legs 44 and 46. The leg 44 has an apertured anchor 48 provided with extending legs 50 and 52. The leg 50 has a projection or pallet 54 acting as the discharging end and is provided with an angled or inclined front face 56 which will hereinafter be described. Similarly leg 52 has a projection or pallet 58 acting as the receiving end, however, no angled face is provided as in 54. A counterweight 60 is disposed adjacent anchor 48. The end of leg 46 is provided with a pair of prongs 62 and 64 having a recess or slot 66 adapted to cooperate with a roller pin 68 provided on a strut 10 of the balance wheel I0.

In operation, the escapement shaft 34 and wheel 32 are adapted to receive power from a main spring of a clock works (not shown). From Fig. 1 it is to be noted that the hair spring 24 has oscillated the balance wheel to a dead beat position wherein the roller pin 68 is in alignment with the center of the anchor 48 and the balance staff pin i2. With power applied to the escapement wheel 32, a tooth thereof is brought into contact with the angular face 56 of the pallet 54, thereby causing oscillation of the anchor 48 to provide a swinging movement of the lever 28 in a counterclockwise direction according to Fig. l. Counterclockwise movement of the lever causes the prong B2 to contact the roller pin 68 and provide a clockwise rotation of the balance wheel Ill. The cutaway portion 26 allows for movement at the prongs 62 and 64 through the shaft l2. The angular face 56 of the pallet 54 provides for a simple self-starting arrangement of the mechanism as will be hereinafter explained. With the anchor 48 and lever 28 moving counterclockwise, the receiving pallet 58 provided is placed in a position to contact a tooth 35 of the escapement wheel 32, however, on the return of the balance wheel H) by the counterforce of the hair spring 24, the escapement lever is moved to the right or clockwise according to Fig. 2, thereby removing the receiving pallet 58 out of contact with the teeth 36 to bring the escapement mechanism to an impulse position as 3 shown in Fig. 2. In this position a tooth 36 of wheel 32 is brought into direct contact with the roller pin 65 on the balance wheel ID to cause a counterclockwise rotation (as shown in Fig. 2) of the balance wheel against the action of the hair spring 24.

Alluding to the self-starting feature, practically all prior self-starting escapement mechanisms are so constructed that there is a drag, or friction, against the balance staff, especially where the application of power is directed through an escapement lever to the balance wheel. This is caused where the teeth of the escapement wheel are provided with apower or lift angle and bearing against the lever directs thi power through the escapement lever against the balance staff. The present structure precludes thi possibility because there is a positive look provided between the escapement teeth 36 and the discharging and receiving pallets. The teeth 35 and the pallets 54 and 58 are not provided with a power or lift angle. The inclined or angled end portion 56 of the pallet as mainly facilitates a self-starting arrangement of the mechanism from a dead beat position as shown Fig. 1, instantaneous as power is applied to the escapement wheel. In any position other than dead beat (Fig. l), the escapement wheel is either moving so as to bear against pin Bil, or is positively locked by either the I receiving or discharging pallets. The angled face 5% has a very slight impulse effect in a clockwise direction on the balance wheel.

With the impulse completed as shown in Fig. it is to benoted that the roller pin as has been moved out of the recess 66 and away from a tooth of the wheel 25, thereby placing the discharging pallet in a locked position with a tooth 36 of the wheel At the completion of the impulse, the counterforce of the hair spring rotates the balance wheel in in a clockwise direction according to Fig. 4 to move pin 68 into the slot 66 and cause movement of the escapement lever in a counterclockwise direction according to Fig. 4, and bring the dischargin face 5 5 out of contact with a tooth and placing the receiving face 58 into contact with tooth E5. The operation continues as long as power is applied to the escapement wheel.

In the present invention the application of power from the escapement wheel directly to the roller pin of the balance wheel to cause rotation thereof, has the advantage over conventional escapement mechanisms of substantially lessening friction on two normally longer lifting faces of the pallets thereof, thereby providing a more ef- 1 ficient operation by the utilization of less torque. In the present mechanism, the speed of oscillation oi the balance wheel, compared to the power and mas of the escapement wheel, tends to limit effectual operation of the balance wheel. Powerbeing applied to the escapement wheel of a certain mass, it follows that it has a certain moment of inertia, and with the balance wheel oscillating at a definite rate of angular velocity as it passes its neutral or dead-beat position, then an equilibrium between the escapement wheel and the balance wheel is reached whenever the power to the escapement wheel is not sufficient to raise the attained angular velocity of the escapement wheel up to or beyond the attained angular velocity of the balance wheel as the balance wheel passes its neutral position. When this point of equilibrium is reached, there ceases any flow of power from the escapement wheel to balance wheel through pin 68 until the rate of angular velocity or" the balance wheel has decreased. In the present structure, the escapement wheel in moving through its impulse, transmits power to the roller pin 68 only when the angular velocity of the roller pin on the balance wheel is less than the attained angular velocity of the escapement wheel. By this arrangement, a wide range of power can be applied to an escapement wheel of a certain mass without causing the balance wheel to oscillate beyond it limits or overloanking, thereby, preventing a timing mechanism from keeping correct time. Furthermore, the additional power provided in the escapement wheel can be utilized for other purposes such as a resetting mechanism in a clock meter and still not cause overloanking of the balance wheel when such additional power is not being used.

From the foregoing, it will be apparent that the present invention permits the use of escapement mechanism to govern the accurate running of heavy duty clocks, and furthermore can be readily utilized in for economical timing devices which are prone to cease running when becoming slightly dirty due to the close ratio of spring power to the escapement wheel. The present high power escapement mechanism would keep this type of time mechanism running irrespective of a small amount of debris and the like. Furthermore, the temperature changes in cheaper time mechanisms affect the lubrication oil and sometimes cause themto stop, and use of the present high power escapement mechanism would preclude this detriment.

Changes may be made in the specification and drawings without departing from the spirit of the invention within the scope of the following claim as set forth.

We claim:

In an escapement mechanism having a power driven toothed escapement wheel, a balance wheel having a roller pin directly engaged by the teeth of the escapement wheel, an escapement lever having a pair of pallets, one of said pallets having an inclined face, a tooth of the escapement wheel disposed in contact with the approximate center of the inclined face at the instant the balance wheel oscillates past the neutral position in a clockwise direction, a forked portion on the escapement lever contacting the roller pin, saidv forked portion and a tooth of the escape wheel both acting on the roller pin at the same distance from the axis of the balance wheel.

GEORGE E. NICHOLSON. J GEN l3. MCGAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain May 28, 1897

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