US3789681A

US3789681A - Apparatus for transforming reciprocating motion into unidirectional rotation

Info

Publication number: US3789681A
Application number: US00131747A
Authority: US
Inventors: Y Kawamura; H Mitsui; K Koike
Original assignee: Suwa Seikosha KK
Current assignee: Suwa Seikosha KK
Priority date: 1971-04-06
Filing date: 1971-04-06
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

Reciprocating motion of a vibrator vibrating at several tens of Hz, such as is used in an electric watch, activates fingers which rotate a ratchet wheel in a single direction. The linkage between the vibrator and the wheel is such that the wheel is advanced during both halves of each cycle of vibration. The fingers can be driven either by one or by both arms of the vibrator.

Description

United States Patent [1 1 Mitsui et a]. Feb. 5, 1974 [5 APPARATUS FOR TRANSFORMING 3,020,425 2/ 1962 Steiner 53/23 D RECPROCATING MOTON $859.33? 1113?? fi 'l i i 31553 yr e UNIDIRECTIONAL ROTATION 2,269,858 1/ 1942 Obszamy 74/ 143 [75] Inventors: Hiromitsu Mitsui; Kenichi Koike,

both of Suwa-Gun; Yoshikazu I v Kawamura, Suwa-Shi, all of Japan Primary Emmmercharles W"? Assistant Examiner--Wesley S. Rathfi', Jr. [73] Assignee: Kabushlki Kalsha Suwa seikosha, Attorney, Agent, or Firm-Blum, Moscovitz, Friedman Tokyo, Japan & Kaplan [22] Filed: Apr. 6, 1971 [21] Appl. No.: 131,747

[57] ABSTRACT [52] US. Cl 74/143, 58/23 D, 74/ 128, Reciprocating motion of a vibrator vibrating at Several 74/577 tens of Hz, such as is used in an electric watch, acti- [51] Int. Cl. 74 575 vates fingers which rotate a ratchet wheel in a single [58] Fleld of Search F 16h/27/02; 74/143 128, direction. The linkage between the vibrator and the 74/577 126; 58/23 23 TE wheel is such that the wheel is advanced during both halves of each cycle of vibration. The fingers can be [56] References C'ted driven either by one or by both arms of the vibrator.

UNITED STATES PATENTS 2/1960 Fresard et al 74/126 7 Claims, 12 Drawing Figures Patented Feb. 5, 1974 Y 3,789,681

5 Sheets-Sheet l Patented Feb. 5 1974 h 3,789,681

5 Sheets-Sheet 2 Patented Feb. 5, 1974 3,789,681

5 Sheets-Sheet 5 FIG? Patented Feb. 5, 1974 3,789,681

5 Sheets-Sheet 4 Patented Feb. 5, 1974 3,789,681

5 Sheets-Sheet 5 APPARATUS FOR TRANSFORMING RECIPROCATING MOTION INTO UNIDIRECTIONAL ROTATION BACKGROUND OF THE INVENTION Conventional types of converters for transforming vibratory into rotational motion use an index finger, a pawl and a ratchet wheel. One end of the index finger is attached to the vibrator and the other end advances the ratchet wheel a distance corresponding to one tooth for each vibration of the vibrator. In general, the finger moves the wheel only during the half cycle of operation during wich the finger is moved toward the wheel. During the half cycle corresponding to the return stroke of the index finger, the pawl holds the wheel motionless. During this half cycle, the vibrator is ineffective for moving the ratchet wheel.

In this type of motion converter, it is necessary that the stroke of the index finger be somewhat longer than the pitch distance. The reason is the need for maintaining the momentum of the index finger. A stroke of 1.5 times the pitch distance has been found to be satisfactory.

SUMMARYOF THE INVENTION In accordance with the present invention, the linkage between the vibrator and the ratchet wheel consists of two fingers rather than one as is conventionally the case. In the thus-improved motion converter, one of the fingers is positioned to advance the ratchet wheel during the forward stroke and the other of the fingers is positioned to advance the ratchet wheel during the return stroke. The amplitude of the stroke need only be about one half of that required in the conventional system; a suitable amplitude is therefore about 0.75 times the pitch distance. The amplitude is in the range from 0.5 to 1 times the pitch distance, and the sum of the strokes of two fingers is in the range from I to 2 times the pitch distance. As a result of operating the vibrator at this reduced amplitude, the energy consumed is only about half that consumed with the conventional drive. An additional advantage of using more than one index finger is that the motion of the ratchet wheel is more uniform; this is particularly valuable in the case of an electric watch where the vibrator is used to drive a gear train connected with the ratchet wheel.

Accordingly, an object of this invention is to reduce the energy lost in a motion transformer which converts reciprocating movement into rotary movement.

Another object of this invention is to stabilize the operation of a motion transformer using a plurality of index fingers.

A further object of the invention is to power an electric wrist watch, minimizing the electrical energy consumed and maximizing the accuracy of the system.

Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.

The invention accordingly comprises the features of construction, combination of. elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the inven tion will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawing, in which:

FIG. 1 is a schematic diagram of the conventional type of motion transfonner;

FIG. 2 is a schematic diagram of an embodiment of the motion transformer;

FIG. 3 is a perspective view of the embodiment of FIG. 2;

FIG. 4 is an exploded view ofv the embodiment of FIG. 2;

FIG. 5 is a partial view of the conventional type of motion transformer;

FIGS. 6 and 7 are partial views of the motion transformer according to this invention; and

FIGS. 8 through 12 are schematic diagrams of other embodiments of the motion transformer according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a conventional motion transformer is shown in which a vibrator 15 is connected to an indexing finger 16 which drives a ratchet wheel 18 in the direction shown by the arrow at each outward stroke of the vibrator 15. During the return stroke of the vibrator, the pawl 13, anchored in a plate, prevents by means of friction reverse rotation of the ratchet wheel 18. A jewel 16a may be mounted in the end of the finger 16 to prolong the life of the system. When the reciprocating index finger is advancing the ratchet wheel, enough rigidity in the finger is required so that it will not buckle; however, on the return stroke of the finger, the finger must be sufficiently flexible so that it can ride over the outside of the next tooth by which the ratchet wheel is to be advanced. The designparameters for such a system are well known and need not be gone into here.

It is important to minimize the energy consumed in driving a ratchet wheel by such a system, particularly when the system is part of an electric watch, since the small space available makes it possible to use only a very small electric battery cell. Adecrease in the rate of energy expenditure will increase the interval between replacements of the cell. The objects of the present invention are achieved by providing a second index finger so mounted to the vibrator and the ratchet wheel that it pulls the ratchet wheel during the return stroke of the vibrator.

Referring to FIG. 2, a transformer in accordance with the present invention is shown schematically. To one arm of the tuning fork type of vibrator 5 are attached a first finger 16 making contact with the wheel 18 at the fingertip 16a, and a second finger 17 making contact with the wheel 18 at the fingertip 17a. It should be noted that in this variation, both fingers are attached to the same arm of the vibrator 15. In FIG. 2, a pair of axes, X--X and Y--Y with the origin coinciding with the ratchet wheel center have been superimposed on the ratchet wheel. When the first fingertip 16a engages the ratchet wheel within the angle A08 and the second fingertip 17a engages the ratchet wheel in the range of angle BOA, the transformer can be operated normally.'The angles AOY and A'OY are approximately 15 degrees and the angles YOB and YOB are approximately 40.

As in the conventional type of ratchet wheel transformer the first finger 16 acts as a-rigid body in advancing the wheel. The second finger 17 operates principally in tension with some side-thrust since neither the direction of the stroke nor the finger itself are exactly tangential to the wheel. It is technically difficult to cut the ratchet wheel teeth so that they are exactly radial in direction. The reason is that the tooth height is only bogt 13 microns and the pitch is only about 25 microns so that is is difficult to control the exact shape of the teeth.

It should be noted that although the first finger l6 operates in a manner similar to that of the single-finger drive, but with a smaller amplitude, the second finger operates by pulling rather than pushing. As a result, the second finger 17 must cross the face of the ratchet wheel 18. If the finger 17 were exactly tangential to the wheel 18, the finger would tend to slip from the wheel during the operating stroke. Positioning the second finger 17 so that it overlies the wheel 18 provides a component of force which holds the fingertip 17a against the tooth by means of which the wheel is being advanced during the return stroke. A further advantage of this arrangement is that the tip 17a will not be dislodged from the wheel even by a relatively severe external shock.

A tuning fork vibrator with the two fingers attached to a single arm is shown in FIG. 3. Such an assembly is shown in more detail in FIG. 4. In this variation, the fingers are leaf springs and both fingers are driven from a single pin on an arm of the tuning fork vibrator 15. The Figure brings out clearly why the pulling finger must cross the face of the ratchet wheel.

Referring to FIG. 5, the method by which a pallet jewel is held in a mount 21 is shown. This mount is suitable for the pushing finger and is conventional in construction. A similar mount 22 is shown for a pulling finger. However, this will be unsuitable for use in the present case since the pulling finger must lie outside the plane of the ratchet wheel, and consequently, the pallet jewel must be off-set from the mount. Three suitable mounts, 23, 24 and 25 are shown in FIG. 6.

The mounts shown in FIG. 6 give rise to some torque as a result of the pallet jewel being off-set. A type of mount in which this is avoided is shown in FIG. 7 where is an arm of the tuning fork, is a pin and the fingertip 17a is held between two fingers 17' and 17", one of these fingers overlying each face of the ratchet wheel 18. This type of mount is particularly effective during the period when the pushing finger 16 is driving the wheel, at which point the pulling finger 17 might be twisted enough during the passage of the jewel-over a tooth so that the finger could be disengaged from the wheel. An external shock at this point would further increase the tendency of the off-set jewel to become disengaged from the wheel.

Another method of avoiding this difficulty is to provide a sufficiently wide leaf spring for finger 17. The elasticity ratio of the leaf spring is proportional to the cube of its thickness and to the first power of its width and so the leaf spring can be properly designed so as to be rigid against the twisting moment when the wheel is advanced by the first finger 16.

It should be noted that the first finger can also be mounted with a double support in the interest of increasing its resistance to displacement by shock.

In contrast to FIG. 2 where the first fingertip 16a is located in the vicinity of the Y axis and the second finger-tip 17a is located in the vicinity of the Y axis and both fingers are attached to one arm of the vibrator at the same point, FIG. 8 shows an arrangement in which the fingertip 16a, is located at the Y axis while the fingertip 17a is located at the Y axis. Experiment has shown that the system operates satisfactorily when the first fingertip 16a engages the ratchet wheel 18 in the range of the angle AOB. In this system the angles AOY and A'OY' are approximately 40 and the angles BOY and BOY are approximately 15. From the standpoint of easy adjustment and economical mass production it is advantageous that the two

leaf springs

16 and 17 are secured to the same point on the tuning fork 15;however, as is shown in FIGS. 9 and 10, the two fingers can be secured to separate points on the tuning fork. In the arrangement of FIG. 9, the system operates satisfactorily when the first fingertip 16a lies within the angle COD and the second fingertip 17a lies within the angle AOB. In this arrangement, the angles AOY and COY are approximately 30 and the angles BOY and DOY are approximately 45. In the arrangement shown in FIG. 10, the system operates satisfactorily when the first fingertip lies within the angle COD and the second fingertip lies within the angle AOB. Here, the angles AOY and COY are approximately 30 and the angles BOY and DOY are approximately 45.

In the arrangement shown thus far, both of the operating fingers were driven from one arm of the vibrator. FIGS. 11 and 12 show how the ratchet wheel may be driven by fingers attached to both arms of the tuning fork vibrator. The principles of operation are similar to those of the arrangements described above. With either type of arrangement, it is necessary that the pulling finger cut across the periphery of the ratchet wheel. Here again, the pulling fingertip 17a may be supported by a single leaf spring somewhat wider than usual to resist the twist introduced by the off-set pallet jewel, or the double suspension described above may be used.

When two operating fingers are fixed to both arms of the tuning fork vibrator and driven from one side of the ratchet wheel as shown in FIGS. 1 l and 12, it is advantageous as the spurious vibration of the ratchet wheel caused by a clearance between the ratchet wheel shaft and the bearing is eliminated.

As is obvious, more than two fingers could be used to drive the ratchet wheel, the plurality of fingers engaging more than one tooth and at different instants with the objective of achieving more uniform motion of the ratchet wheel, and of the gear system which may be attached thereto.

The devices of the present invention decrease the amplitude of vibration needed for driving the ratchet wheel by a factor of approximately two, render the motion of the ratchet wheel more uniform, and are strongly resistant to external shock. This type of motion transformer is applicable to many industrial usages, and is particularly suitable for use in electrical watches.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

What is claimed is:

1. A motion transformer suitable for exerting forces of a magnitude sufficient for dirving an electric watch comprising a tuning fork, a finger operatively attached at one end to said tuning fork, a ratchet wheel having at least one face and having a toothed periphery engaged with the other end of said finger, said finger overlying said one face of said ratchet wheel and being thereby adapted to advance said ratchet wheel in a single direction by pulling on a tooth of said ratchet wheel.

2. A motion transformer as defined in claim 1 further comprising at least one further finger operatively attached at one end to said tuning fork the other end being engaged with the toothed periphery of said ratchet wheel without overlying a face thereof and being thereby adapted to advance said ratchet wheel in said single direction by pushing on a tooth of said ratchet wheel.

3. A motion transformer suitable for exerting forces of a magnitude sufficient for driving an electric watch comprising a tuning fork, a finger operatively attached at one end to said tuning fork, a ratchet wheel having at least one face and having a toothed periphery engaged with the other end of said finger, said finger overlying said one face of said ratchet wheel and being thereby adapted to advance said ratchet wheel in a single direction by pulling on a tooth of said ratchet wheel, and a second finger operatively attached at one end to said tuning fork, the other end being engaged with the toothed periphery of said ratchet wheel without overlying said face thereof and being thereby adapted to advance said ratchet wheel in said single direction by pushing on a tooth of said ratchet wheel, said fingers being operatively attached at a single point on one arm of said tuning fork.

4. A motion transformer suitable for exerting forces of a magnitude sufficient for driving an electric watch comprising a tuning fork, a finger operatively attached at one end to said tuning fork, a ratchet wheel having at least one face and having a toothed periphery engaged with the other end of said finger, said finger overlying said one face of said ratchet wheel and being thereby adapted to advance said ratchet wheel in a single direction by pulling on a tooth of said ratchet wheel, and a second finger operatively attached at one end to said tuning fork, the other end being engaged with the toothed periphery of said ratchet wheel without overlying said face thereof and being thereby adapted to advance said ratchet wheel in said single direction by pushing on a tooth of said ratchet wheel, said fingers being operatively attached at 2 points spaced apart from each other on one arm of said tuning fork.

5. A motion transformer suitable for exerting forces of a magnitude sufficient for driving an electric watch for converting a vibratory motion of a vibrator into a rotary motion comprising a rotatably mounted ratchet wheel, two thin leaf elements respectively attached to a part of said vibrator reciprocating in opposite directions relative to a tooth of said ratchet wheel, and a first pawl and a second pawl means secured to ends of two' thin leaf elements, said two pawl means acting in alternation during each cycle of vibration of said vibrator and being engaged with the teeth of said ratchet wheel, at least one of said thin leaf elements so placed as to overlie one face of said ratchet wheel and engage with said ratchet wheel.

6. A tuning fork suitable for exerting forces of a magnitude sufficient for driving an electric watch, comprising a finger operatively attached at one end to one arm of said tuning fork, a ratchet wheel having at least one face and having a toothed periphery engaged with the other end of said finger, said finger overlying said one face of said ratchet wheel and being thereby adapted to advance said ratchet wheel in a single direction by pulling on a tooth of said ratchet wheel, and a second finger operatively attached at one end to the other arm of said tuning fork, the other end of said finger being engaged with the toothed periphery of said ratchet wheel without overlying a face thereof and being thereby adapted to advance said ratchet wheel in said single direction by pushing on a tooth of said ratchet wheel.

7. A motion transformer suitable for exerting forces of a magnitude sufficient for driving an electric watch, comprising vibrating means, a finger operatively attached at one end to said vibrating means, a ratchet wheel having two faces and a toothed periphery engaged with the other end of said finger, said finger comprising two parallel members, each overlying a different face of said ratchet wheel, and a pallet jewel mounted between the other ends of said members, said pallet jewel engaging the toothed periphery of said ratchet wheel.

Claims

5. A motion transformer suitable for exerting forces of a magnitude sufficient for driving an electric watch for converting a vibratory motion of a vibrator into a rotary motion comprising a rotatably mounted ratchet wheel, two thin leaf elements respectively attached to a part of said vibrator reciprocating in opposite directions relative to a tooth of said ratchet wheel, and a first pawl and a second pawl means secured to ends of two thin leaf elements, said two pawl means acting in alternation during each cycle of vibration of said vibrator and being engaged with the teeth of said ratchet wheel, at least one of said thin leaf elements so placed as to overlie one face of said ratchet wheel and engage with said ratchet wheel.