US3484804A

US3484804A - Device for transforming an oscillating motion into a unidirectional rotation

Info

Publication number: US3484804A
Application number: US786655A
Authority: US
Inventors: Jean Hermann; Daniel Paratte; Max Forrer
Original assignee: Centre Electronique Horloger SA
Current assignee: Centre Electronique Horloger SA
Priority date: 1968-02-16
Filing date: 1968-12-24
Publication date: 1969-12-16
Anticipated expiration: 1986-12-16
Also published as: DE1903880B2; CH508907A; CH228268A4; FR1587289A; DE1903880A1

Description

.1. HERMANN ET AL DEVICE FOR TRANSFORMING AN OSCILLATING MOTION INTO A UNIDIRECTIONAL ROTATION Filed Dec. 24

5 Sheets-Sheet 1 Dec. 16. 1969 J. HERMANN ET AL 3,484,804

DEVICE FOR TRANSFORMING AN OSCILLA'IING MOTION INTO A UNIDIREGTIONAL ROTATION Filed Dec. 24. 1968 3 Sheets-Sheet 2 Dec. 16. 1969 HERMANN ET AL 3,484,804

DEVICE FOR TRANSFORMING AN OSCILLA'IING MOTION INTO A UNIDIRECTIONAL ROTATION Filed D90. 24, 1968 3 Sheets-Sheet 5 United States Patent 3,484,804 DEVICE FOR TRANSFORMING AN OSCILLAT- ING MOTION INTO A UNIDIRECTIONAL ROTATION Jean Hermann, Daniel Paratte, and Max Forrer, Neuchatel, Switzerland, assignors to Centre Electronique Horloger S.A., Neuchatel, Switzerland, a Swiss company Filed Dec. 24, 1968, Ser. No. 786,655 Claims priority, application Switzerland, Feb. 16, 1968, 2,282/68 Int. Cl. G04c 3/00 US. Cl. 58-23 12 Claims ABSTRACT OF THE DISCLOSURE Two oscillating pawls alternately drive a ratchet of a horological mechanism step-by-step in the same sense, each pawl temporarily holding the wheel against return movement while the other pawl is inactive.

BACKGROUND OF THE INVENTION The present invention concerns a device for transforming an oscillating motion into a unidirectional rotation.

The problem of the transformation of an oscillating motion into a rotary motion is well known in horology, as well as in the case of horological pieces having a spring driving motor as in the case of horological pieces having a regulating motor driven by electrical means.

In this last category, two kinds of mechanical transformers are generally used, the transformer with a pawl mounted on a resilient strip and the driving anchor which engages the teeth of the wheel in order to cause its rotation.

The transforming devices provided with a pawl have the disadvantage of requiring a second pawl to prevent a return motion of the driven wheel, since the wheel is locked in one direction only by the positioning pawl, which allows this wheel to advance accidentally under the influence of too great an impulse received from the driving pawl or owing to the effect of a shock when the same pawl is in its position of rest.

The anchor transforming devices have nearly radial engagement with the driven wheel, i.e. nearly perpendicular to the motion of the wheel, which causes considerable friction and consequently a low efiiciency.

SUMMARY OF THE INVENTION The present invention enables the abovementioned disadvantages to be remedied. It consequently concerns a device for transforming an oscillating motion into a unidirectional rotation, comprising two members connected to a support mounted to oscillate around an axis and arranged on this support in such a manner as to alternatively engage in the teeth of a wheel for driving the latter step-by-step, characterized in that the wheel has an odd number of teeth, and in that the trajectory of each one of the members intersects the outer circumference of the wheel in two points the connecting radii of which form in the centre of the wheel an angle which is practically equal to the pitch of the teeth, the chords respectively connecting the points of intersectoin of the circumference with the trajectory of each one of the members being perpendicular to a common diameter of this wheel.

The force applied by such a transforming device is practically tangential to the wheel and thus applied in the direction of its rotation, so that friction is considerably reduced and the efiiciency increased.

3,484,804 Patented Dec. 16, 1969 BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a side view, partly in cross section, of a transforming device of the invention incorporated in a horological mechanism.

FIGS. 2 and 4 are schematic plan views of the transforming device of FIGURE 1.

FIG. 5 is a schematic end view of the transforming device of FIG. 1, showing the wheel 14 and the relative angular positions of the

pawls

12 and 13.

FIGS. 6 and 7 are schematic plan views of another embodiment.

FIG. 8 is a perspective view of a variant of the embodiment shown in FIGS. 1 to 5.

FIGS. 9 to 11 are plan views of another variant.

FIG. 12 is a view in elevation schematically showing the resilient parts illustrated in FIGS. 9 to 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The horological mechanism shown in FIG. 1 comprises a motor 1 oscillating around an axis 2 parallel to the upper and lower faces of the movement, respectively 3 and 4. The movable armature of the motor comprises a coil 5 in the shape of a frame secured by means of an adhesive in two recesses 6 and 7 respectively formed in the inner ends of two rods 8 and 9 coaxial with the axis 2, and the outer ends of which are pivoted in bearings 10 and 11, respectively. The rod 8 carries two rigid-

armed pawls

12 and 13 secured to this rod and the free ends of which are arranged on either side of a wheel 14 pivoted around an axis 15 which is perpendicular to and in the same plane as the axis 2 of the motor 1. This wheel 14 is connected by its pinion 16 to the demultiplicating gear train of the indicating hands as in the classical horological mechanisms.

As may be seen in the FIGS. 2 to 4, the wheel 14 is provided with ratchet teeth. The two

pawls

12 and 13 describe around and axis of oscillation 2 two planes parallel to the axis of rotation 15 of the wheel 14 which intersects the outer circumference of the wheel, as defined by the tips of the teeth, along a chord, joining the tips of two adjacent teeth. As the wheel 14 has an odd number of teeth, a tooth is always diametrically opposite to a gap. The two

pawls

12 and 13 occupy a predetermined angular position in relation to one another around the axis 2. Thus, the path of movement of each pawl intersects the outer circumference of the Wheel 14 at two points, such that the radial lines drawn therethrough define an angle substantially equal to the pitch of the wheel teeth. The two chords thus defined by the movement of the pawls are perpendicular to a common diameter of the wheel.

The core of the armature coil 5 extends between the two inner ends of the rods 8 and 9, and can be considered an extension or part of the rod 8.

In FIG. 2, the face of the pawl 12 rests against the tops of two teeth of the wheel 14 which is thus angularly positioned. The

pawls

12 and 13 which were rotating in the direction of the arrow F around the axis 2 have arrived the end of their travel in the position shown in this figure and are at the beginning of a rotation in the opposite direction F1. The pawl 12 is first disengaged from the wheel 14 as shown in FIG. 3 and the pawl 13 comes into contact with a tool of the wheel 14 which is diametrically opposite to the chord joining the two adjacent teeth resting against the face of the pawl 12. The tooth in contact with the pawl 13 is displaced by the latter until its summit slips against the face of the pawl 13 which forms a chord with the summit of the adjacent tooth. At this moment the direction of oscillation changes until the pawls return to the position shown in FIG. 2.

In the embodiment illustrated in FIGS. 6 and 7, the principle of operation is identical with that of the FIGS. 2 to 5. This embodiment differs from the preceding one by the fact that the axes and 17 respectively of the wheel 14 and the oscillator are parallel. The

pawls

18 and 19 are consequently no longer axially spaced around the axis of oscillation, but are concentric with this axis. As the radii separating the

pawls

18 and 19 from the axis of rotation are dilferent, the angular distribution of the contact of the teeth with each of the arms is consequently no longer identical. The advance of the wheel 14 is effected in the same way as described above, but the positioning is no longer obtained by means of a plane surface but by means of the arcs of circles of the arms of the

pawls

18 and 19 which are concentric with the axis of oscillation 17.

A variant of the first embodiment is illustrated in FIG. 8 in which the

pawls

12 and 13 are secured to a movable frame 20 forming part of an electro-dynamic driving system. This part 20 and the

pawls

12 and 13 can be obtained in the shape of a single moulding which leads to an extremely simple practical solution.

In the described embodiments, there exists a very short moment during which the wheel 14 is not locked, the moment between the instant when a pawl leaves the wheel and the instant when the other pawl comes into contact with a tooth. This diiference between the release of the wheel by one pawl and the coming into contact of the other pawl with a 'tooth is made necessary for reasons relating to the safe operation, in order to avoid the risk of the mechanism becoming blocked. The FIGS. 9 to 12 ilustrate a variant intended to ensure continuous locking whilst avoiding all risks of seizing or blocking of the mechanism. To this end, each

pawl

12 and 13 is provided at its driving end with a

resilient part

21 and 22 respectively which may be constituted by various means. The operation illustrated in thesefigures and in particular in FIG. 10 shows the function of this resilient zone. In fact, it may be seen that if the pawls are rotating in the direction F1, for instance, the resilient zone 21 of the pawl 12 is still in contact with a tooth of the wheel 14 whilst the resilient zone 22 of the pawl 13 has come into contact with a tooth of the wheel 14. As the wheel is still locked by the pawl 12, the zone 22 is compressed, and when the pawl 12 has released the tooth it is retaining, the resilient zone 22 will be able to return to its normal position driving the wheel 14 until the pawl arrives in the position shown in FIG. 11, after which the pawls begin to rotate in the direction F to come to the position shown in FIG. 9 passing meanwhile through the compression phase of the resilient zone 21, as described with reference to FIG. 10 for the resilient zone 22.

FIG. 12 illustrates an embodiment for obtaining the

resilient zones

21 and 22. Two

springs

23 and 24 are secured at, or near to, the base of each pawl in such a manner as to create a resilient contact between the wheel 14 and the

pawls

12 and 13.

What is claimed is:

1. Device for transforming and oscillating motion into a unidirectional rotation, comprising a toothed wheel mounted free to rotate, the tips of the teeth thereof defining a wheel outer circumference, a support mounted to oscillate about an axis, two members on said support and moving therewith for alternately engaging the teeth of said wheel to drive the latter step-by-step in one direction, and wherein the improvement comprises that said wheel incorporates an odd number of teeth, and that the path of movement of each of said two members intersects said wheel outer circumference at two points the radial lines of which define an angle substantially equal to the pitch of the wheel teeth, and wherein the respective chords connecting the two intersections of the path of movement of each said member with the said wheel outer circumference are perpendicular to a common diameter of said wheel, whereby each said member locks said wheel, at respectively different times, against return movement for a part of each complete oscillation of said support.

2. The device as defined in claim 1, wherein the axis of oscillation of said support is perpendicular to the axis of said Wheel, and each said member has at least one surface perpendicular to the axis of oscillation of said support.

3. The device as defined in claim 1, including a driving face for each said member that contacts the teeth of said wheel, and resilient means arranged in front of each said driving face for contacting a tooth of said wheel while the other said member is still locking said wheel, whereby the latter is never free to rotate in the return direction.

4. The device as defined in claim 3, wherein each said member projects from said support, and said resilient means are each a springy strip secured at, or near to, the base of a respective said member and which diverges from its member in the direction of the end thereof remote from said support.

5. The device as defined in claim 1, wherein the axis of oscillation of said support is parallel to the axis of said wheel.

6. The device as defined in claim 5, including a surface incorporated by a respective said member for contacting two adjacent teeth of said wheel for locking the latter in position, after the respective member has driven it one step, for a part of one complete oscillation of said support, and wherein said surface of each said member defines an arc of a circle concentric with the axis of oscillation of said support.

7. The device as defined in claim 1, including an oscillating motor, a coil constituting the armature for said motor and mounted on said support, and wherein said support constitutes the core of said motor coil.

8. The device as defined in claim 2, including an oscillating motor, a coil constituting the armature for said motor and mounted on said support, and wherein said support constitutes the core of said motor coil.

9. The device as defined in claim 7, wherein said members are integral with said support.

10. The device as defined in claim 8, wherein said members are integral with said support.

11. The device as defined in claim 1, wherein each said member is a pawl.

12. The device as defined in claim 1, wherein said wheel is a ratchet wheel and each said member is a pawl, and said wheel and members are part of the works of a horological mechanism.

References Cited UNITED STATES PATENTS 2,570,170 10/1951 Viti 58-116 3,351,788 11/1967 Favre 5823 RICHARD B. WILKINSON, Primary Examiner EDITH C. SIMMONS, Assistant Examiner U.S. Cl. X.R. 74-25