US3623316A

US3623316A - Clubtooth lever escapement

Info

Publication number: US3623316A
Application number: US25717A
Authority: US
Inventors: Kenji Abe
Original assignee: Suwa Seikosha KK
Current assignee: Suwa Seikosha KK
Priority date: 1969-04-16
Filing date: 1970-04-06
Publication date: 1971-11-30
Anticipated expiration: 1988-11-30
Also published as: FR2162414A1; FR2162414B1; NL7216518A; CH558870A4; CH558870A; GB1417417A; IT1018051B; BE792417A

Abstract

CLUBTOOTH LEVER ESCAPEMENT WITH HIGH TRANSMISSION EFFICIENCY HAVING AN ESCAPE WHEEL AND AN ANCHOR AND SATISFYING AT LEAST ONE OF 1.0>LG/LAI$0.85 AND 1.0>G/LAD$0.85. WHERE LG IS THE LENGTH OF THE IMPULSE FACE OF THE ESCAPE WHEEL TOOTH, LAI IS THE LENGTH OF THE IMPULSE FACE OF THE ENTRY PALLET JEWEL OF THE ANCHOR AND LAD IS THE LENGTH OF THE IMPULSE FACE OF THE EXIT PALLET JEWEL OF THE ANCHOR.

Description

Nov. 30, 1.71 KENJI ABE CLUBTOOTH LEVER ESCAPEMEN'I 3 Sheets-Sheet 1 Filed April 6, 1970 F/GJ FIG.2

Nov. 30, 1971 KENJI ABE CLUBTOOTH LEVER ESCAPEMENT 3 Sheets-Sheet 2 Filed April 6, 1970 New. 30, 1971 KENJI ABE CLUBTOOTH LEVER ESCAPEMENT 3 Sheets-Sheet 5 Filed April 6, 1970 T MN N 1 m M we N S M E Tm MM 5 C RE P L woatfitwm N m United States Patent O 3,623,316 CLUBTOOTH LEVER ESCAPEMENT Kenji Abe, Suwa-shi, Japan, assignor to Kabushiki Kaisha Suwa Seikosha, Tokyo, Japan Filed Apr. 6, 1970, Ser. No. 25,717 Claims priority, application Japan, Apr. 16, 1969, 44/28,972 Int. Cl. G04b 15/00 US. Cl. 58-116 3 Claims ABSTRACT OF THE DISCLOSURE Clubtooth lever escapement with high transmission efliciency having an escape wheel and an anchor and satisfying at least one of 1.0 L 120.85 and 1.0 L /L 20.85, where L is the length of the impulse face of the escape wheel tooth, L is the length of the impulse face of the entry pallet jewel of the anchor and L is the length of the impulse face of the exit pallet jewel of the anchor.

SUMMARY OF THE INVENTION The present invention relates toan improved clubtooth lever escapement for a timepiece, and more particularly to the transmission efficiency of the escapement. The length of the respective impulse faces of the escape wheel tooth, the entry pallet jewel and exit pallet jewel are determined in accordance with a fixed relationship to increase the transmission efficiency of the whole escapement.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a plan view of a conventional clubtooth lever escapement;

FIG. 2 shows the operating relationship between the driving part (hereinafter referred to as an escape wheel portion) and the driven part (hereinafter referred to as an anchor portion) when they rotate in one direction;

FIGS. 3 and 4 show the operating relationship between an escape wheel tooth and an entry pallet jewel;

FIG. 5 shows the operating relationship between an escape wheel portion and an anchor portion when the latter rotates in the opposite direction;

FIG. 6 is a graph showing the relationship between the 'mainspring torque and the amplitude of the balance in a conventional escapement and also in an escapement according to the present invention; and

FIG. 7 is a graph showing the relationship between the frequency and the transmission efiiciency in a conventional escapement and also in an escapement according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION In FIG. 1, a clubtooth lever escapement is composed of an escape wheel 1, an anchor 2 and a roller table 3 of a balance. The roller table 3 is coaxially mounted on a balance staflf 13. When the roller table 3 rotates in the direction of the arrow 16 with the rotation of the balance, a roller jewel 12 strikes against a horn 11 of the anchor. This permits an entry pallet jewel 7 to leave its lock face 8. As the escape wheel 1 rotates in the direction of the arrow 14, the anchor 2 receives rotation torque in the direction of the arrow 15 and transmits the energy through the horn 11 of the anchor and the roller jewel 12 to the balance. An exit pallet jewel 7 then locks an escape wheel tooth against rotation and at the same time the anchor 2 is pressed against a banking pin '10. While the balance rotates in the opposite direction to the arrow 1l6, said exit pallet jewel takes the same actions as said entry pallet jewel.

ice

The escape wheel tooth is provided with a lock face 5 and an impulse face 6. The entry pallet jewel 7 of the anchor is provided with a lock face 8 and an impulse face 9, while the exit pallet jewel 7 is provided with a lock face 8 and an impulse 9. Therefore, the energy transmission from the escape wheel 7 to the anchor 2 is accomplished at the impulse faces thereof.

Generally the following matters have been studied in order to improve the transmission efficiency of the clubtooth lever escapement.

(l) The friction caused in the impulse face 6 of the escape wheel tooth and in the impulse face 9 (9) of the anchor pallet jewel 7 (7') has been reduced as much as possible by the following treatment. Each face was sufficiently polished, and the lubricant supplied thereto. Materials having a low frictional coefficient such as ruby were applied to the pallet jewels, and contact surfaces were made smaller.

(2) The escapement was made small and thin to the greatest extent possible from the viewpoint of manufacturing, engineering, and design by employing electroforming or using aluminous materials so that the loss of the transmission energy was decreased to increase the transmission efficiency.

(3) The loss of the transmission energy was decreased by reducing the dropping angle of the escape wheel.

The above mentioned experiments however have not brought about the desired effect of the increase on the transmission efliciency of the escapement.

On the other hand, the purpose of the present invention is to provide extremely high accuracy to a time piece by maintaining the relationship between the impulse face of the escape wheel tooth and that of the pallet jewel so as to obtain a high efliciency of the escapement.

By maintaining the relations l.0 L /L O.85 and l.0 L /L 0.85, where L is the length of the impulse face of the escape wheel tooth, L is the length of the impulse face of the entry pallet jewel of the anchor, and L is the length of the impulse face of the exit pallet jewel of the anchor, the transmission efiiciency of the escapement can be greatly improved.

The high transmission efficiency of the whole escapement can be obtained by improving the efficiency of the entry pallet and the exit pallet separately. In other words, if either of the above-mentioned relations is satisfied, the efficiency can also be improved to some extent. But it is preferable to design an escapement so as to satisfy both relations above.

Of course the conventional experiments, mentioned heretofore, to increase the transmission efficiency, can also be applied to the present invention to further increase the efiiciency.

The present invention will be disclosed hereinafter theoretically in the accompanying drawings.

Referring to FIG. 2, the escape wheel portion which rotates on an axis of O in the direction of the arrow rotates the anchor portion on an axis of 0 by the force F passing through the point of contact C. F represents the force without friction. on represents a friction angle. P and P is the length of a perpendicular line drawn on the extension line of the force F from O and 0 respectively. P and P is also the length of a perpendicular line drawn on the extension line of the force F. A and B represent the distance between 0, and C, or between O and C, respectively. L represents the length between 0- and 0 a is CO O 0 is O CO and [3 is (18OCO O A is an angle formed with a segment of a line 0 C and F. and represent angles in polar coordinates where 0 and 0 are the origin thereof correspondingly.

Generally from FIG. 2, the transmission efiiciency 1; is given by the following equation:

And assuming that torque of the escape wheel portion is M, we can write:

FP '=M Since the emitting energy of the escape Wheel side is equal to the absorbing energy of the anchor side under no friction, the following equation can be obtained:

Assuming that the amount of M is constant, the Equation 1 and 2 lead to:

Further from the equations 3 and 4,

I I f 1 2 /f 5) In FIG. 2, we can read P =A sin (1r0)\) (6) P =B sin (7) P '=A sin (1r0)\+0c) (8) P '=B sin ()\a) (9) FIG. 3 shows the operating relationship in which the impulse face of the entry pallet jewel is lifted by the locking corner 17 of the escape wheel tooth. The marks employed in FIG. 3 mean the same as those in FIG. 2.

R is the length between 0 and the locking corner 17 of the escape wheel tooth. R is the length between 0 and the leaving corner 18 of the escape wheel tooth. Act is an angle formed with the segments of lines R and R S is the length between 0 and the locking corner 19 of the anchor. S is the length between 0 and the leaving corner 20 of the anchor. Afr is an angle formed with the segments of lines S and S Now in order to obtain the transmission efficiency of a clubtooth lever escapement under the condition shown in "FIG. 3, the following equations are substituted into the

Equation

6, 7, 8 and 9. Namely,

A 6+ cos- R R sin Aa /L +S +2LS cos B R1 +Rg +2R1Rg cos Au. fi 2+ fl Thus the total static transmission efliciency of the entry pallet side can be obtained with consideration for the transmission efiiciency due to impulse above-mentioned and the losses due to disengagement and dropping of the escapement.

FIG. 5 shows the operating relationship in which the escape wheel tooth is impelled against the exit pallet jewel. As is apparent from FIG. 5, the total transmission efliciency 1 of the exit pallet side can be calculated in approximately the same manner as calculated in the case of the entry pallet side, by employing the following Therefore the transmission efficiency 1 between the escape wheel and the anchor is given:

where is the rotating angle of the escape wheel while the entry pallet side is operated. is that of the exit pallet side.

It was found from the calculation by the computer that the extremely high transmission efiicienoy could be obtained when satisfying the following relations:

L 1 0.85 (12) L /L 20.85 (13) where L /R +R 2R R cos AOL is the impulse face length of the escape wheel tooth (length between 17 and 18 in FIG. 3);

L /S +S -2S S cos A13 is the impulse face length of the entry pallet jewel (length between 19 and 20 in FIG. 3); and

L /S +S 2S S cos A 6 is the impulse face length of the exit pallet jewel.

S S and AB (not shown) of the exit pallet jewel correspond to S S and AB of the entry pallet jewel respectively.

If L /L ZLO, L /L l.0, the Width of the pallet jewel must be made small or with the conventional pallet jewel the width of the escape Wheel tooth must be made fairly large. Therefore if the conventional escape wheel and the anchor are employed with only a slight change it requires the following ratios i.e. L /L and L /L less than 1.0 respectively. Even if the width is less than 1.0 the transmission efiiciency can be increased more than 20 to 30% compared with that of the conventional escapement. It is also economical since great change in design or structure is not required for the conventional watch parts.

Minimization of the pallet jewel in width makes it difiicult to cut or polish rubies which are used as the materials for pallet jewels.

In the conventional clubtooth escapement, the following relations can be given:

and

Namely, in the conventional escapement, the length of the impulse face of the escape wheel tooth is fairly shorter than that of the anchor.

As can be understood from the above description, the relations among L L and L have not been considered in the improvement of the efliciency of the conventional escapement. In other words, the relation among L L and L shown above have been employed only customarily in the conventional escapement and they have been decided regardless of the improvement of the eificiency of the escapement.

On the other hand, in the present invention, the improvement of the escapement efiiciency can be performed by keeping the relations among L L and L satisfactorily.

The results of the experiment where the escapement according to the present invention is compared with the conventional one will be disclosed hereinafter only by the examples.

In this case, the conventional escapement has L /L -0.5 and L /L -0.5, while the escapement according to the invention has L /L -0.9 and L /L -0.9.

Two kinds of wrist watches with the above-mentioned escapements, which show the moment of inertia of 910 mg. mm. and 36,000 vibrations/hour respectively, were compared with each other in the amplitude in the horizontal position.

The results are as follows:

FIG. 6 shows the relationship between the amplitude and the torque in the horizontal and vertical position in the conventional escapement and the escapement according to the invention.

As a result, the ratio of the mainspring torque to the same amplitude of 210 between the conventional escapement having the torque of 120 gem. and the escapement having the torque of 100 gcrn. according to the invention is 120/ 100:1.2. Thatis, the transmission efiiciency in the escapement according to the invention can be increased by 20%.

Further, since the transmission efiiciency of the train wheels is generally 70% and Q value of the balance is approximately 300, the transmission efliciency of the escapement can be calculated from Table I. Namely, the transmission efliciency of the conventional escapement is 31%, while that of the escapement according to the invention is 37%. In other words, the transmission efliciency of the escapement according to the invention can be increased by about 1.2 times as that of the conventional escapement.

FIG. 7 shows the transmission efficiency of the timepieces having the different frequency. As can be seen from FIG. 7, the transmission efficiency of the escapement according to the invention is far higher than that of the conventional escapement, making it possible to decrease the isochronism error caused by a hairspring, positional error and escapement error and thus insuring the production of timepieces with extremely high frequency.

What is claimed is:

1. A clubtooth lever escapement with high transmission efficiency comprising an escape wheel having a plurality of teeth, each of said teeth having an impulse face; and an anchor having an entry pallet jewel and an exit pallet jewel, each of said entry and exit pallet jewels being formed with an impulse face for cooperative engagement with said escape wheel teeth for the transmission of energy from said escape wheel to said anchor, and wherein 1.0 L /L 20.85, where L is the length of the impulse face of the escape wheel teeth, and L is the length of the impulse face of the entry pallet jewel of the anchor.

2. A clubtooth lever escapement as recited in claim 1, wherein 1.0 L /L z0.85, where L is the length of the impulse face of the exit pallet jewel of the anchor.

3. A clubtooth lever escapement with high transmission efliciency comprising an escape wheel having a plurality of teeth, each of said teeth having an impulse face; and an anchor having an entry pallet jewel and an exit pallet jewel, each of said entry and exit pallet jewels being formed with an impulse face for cooperative engagement with said escape wheel teeth for the transmission of energy from said escape wheel to said anchor, and wherein 1.0 L /L 20.85, where L is the length of the impulse face of the escape wheel teeth and L is the length of the impulse face of the exit pallet jewel of the anchor.

References Cited UNITED STATES PATENTS 856,091 6/1907 Ohlson 58-116 1,044,054 11/ 1912 Jeanmairet 58-116 1,928,554 9/1933 Beehler 58-116 2,444,178 6/1948 Weinberger 5 8-116 X 3,425,212 2/1969 Verde 58-116 FOREIGN PATENTS 1,096,039 12/ 1967 Great Britain 58-116 342,897 1/1960' Switzerland 58-116 RICHARD B. WILKINSON, Primary Examiner S. A. WAL, Assistant Examiner