HK1186535B - Column wheel and chronograph mechanism including the same - Google Patents

Description

Column wheel and chronograph mechanism including the same

Technical Field

The present invention relates to a three-stroke chronograph mechanism (timer-chronograph mechanism) arranged to control a chronograph hand and at least one counting hand for starting and stopping these hands and returning them quickly to their starting point by successive applications of pressure on the same button as required. The invention relates more particularly to a three-stroke chronograph mechanism of the above-mentioned type comprising a column wheel, in which successive applications of pressure on a push-button have the effect of gradually increasing the angular position of the column wheel.

Background

Chronograph mechanisms corresponding to the above definition are well known to the person skilled in the art. In particular, a work entitled "Le chronograph, son coordination, sa parration" by mr. B Humbert published by edition script s.a., by La Conversion (Switzerland) in 1990, details a timepiece of the above type, giving characteristics of a number of known variants.

Figure 1 accompanying this description shows a known column wheel. As shown, the column wheel is formed primarily of a ratchet wheel "r" and six teeth or columns "e" carried on the edge of the ratchet wheel. Today, the ratchet and the post are usually integral with each other, and as shown in the figures, the cross-section of the post is traditionally shaped as a substantially truncated triangle. The shape of this feature is associated with the use of a trimming cutter that molds the post into the thickness of the plate of the ratchet. The column wheel typically carries five or six columns (six in the example shown), and in the case of a three-stroke chronograph, the ratchet comprises 3 teeth for each column (in the example shown, the ratchet comprises 18 teeth in total). When the column wheel is not being actuated, it is held in a stable angular position by a jumper spring (not shown), the end of which rests against the ratchet. The column wheel is also controlled by the action of a pawl (not shown). The pawl is arranged to cooperate with the ratchet and is controlled by the push button. Each application of a press on the button has the effect of moving the pawl to move the column wheel forward by the angular value of one ratchet tooth.

Usually, three presses on the push-button are required in order to replace one guide post with the previous one, which corresponds to the traditional three functions of the timepiece: start, stop, and reset. These functions are released by a pivoting control part (or lever) which is arranged to be actuated in turn by the guide post of the guide post wheel. The pivoting member is arranged such that the track defined by the step advance of the guide post intersects the beak of the pivoting member. Thus, when the guide post comes into contact with the beak of the pivoting part, the guide post forces the beak to rise. Then, as the guide post continues to move forward, the guide post is released from under the beak which can fall into the space between the two guide posts, thus allowing the pivoting part to fall. It is therefore evident that it is the angular position of the column wheel that determines the release or interruption of the function of the chronograph mechanism.

In order to obtain an optimum precision with respect to the precise moment when the beak of one bar or the other is raised and falls down into the space between two guide posts, the beaks of the various pivoting parts are given a very complex shape. Furthermore, once the chronograph mechanism is assembled, it is generally necessary to trim the beak of the pivoting part, which adds considerably to the cost price of the timepiece. Further, the beak portion of the pivot control member may have a very wide variety of shapes as shown in the view of fig. 2, which fig. 2 is taken from the aforementioned works. This diversity of shapes makes it difficult to standardize the production of timepieces. Finally, the view of fig. 2 also shows that the beak has a width greater than the width of the guide post. As a result of this very common feature, in the space between two guide posts, the available length of stroke for the beak is reduced, so that the rod and the guide posts are subjected to considerable mechanical forces. Therefore, it is useful to manufacture a timepiece mechanism having a mechanical strength smaller than that of the conventional mechanism.

Disclosure of Invention

The object of the present invention is to overcome the above mentioned drawbacks of the prior art. The present invention achieves this object by providing a column wheel according to the appended claim 1 and a chronograph mechanism according to claim 7.

Drawings

Other characteristics and advantages of the invention will appear clearly on reading the following description, given purely by way of non-limiting example, with reference to the accompanying drawings, in which:

figure 1 is a top view of a three-stroke column wheel of the prior art.

Figure 2 is a schematic top view showing the various possible interactions between the guide post and the beak of the pivoting part in the chronograph mechanism of the prior art.

Figure 3 is a front view of the chronograph mechanism according to a particular embodiment of the invention, in which the chronograph mechanism is reset to zero and ready to be activated.

Figure 4 is a front view of the chronograph mechanism of figure 3 at the moment of its activation.

Figure 5 is a front view of the chronograph mechanism of figures 3 and 4 during operation.

Figure 6 is a front view of the chronograph mechanism of figures 3 to 5 at the moment when the mechanism is stopped.

Figure 7 is a front view of the chronograph mechanism of figures 3 to 6, at rest.

Figure 8 is a front view of the chronograph mechanism of figures 3 to 7 at the moment when the mechanism is reset to zero.

Figure 9 is a top view of the column wheel of the chronograph mechanism of figures 3 to 8.

Fig. 10 is a perspective view of the column wheel of fig. 9.

Detailed Description

Referring first to fig. 9 and 10, which fig. 9 and 10 show a column wheel 40 according to a particular embodiment of the invention, it can be seen that the column wheel is mainly formed by a ratchet arrangement 42 and four columns 44 evenly distributed in the circumferential direction of the ratchet arrangement. The column wheel also includes a hub 46, the hub 46 being arranged to be pivotally mounted about the axis of the chronograph mechanism (not shown in fig. 9 and 10). Fig. 9 also contains an arrow mark R for indicating the direction of rotation of column wheel 40. It should be noted that in this example, the direction of rotation is clockwise.

In the example shown, the column wheel also includes four arms 48, the four arms 48 respectively connecting the four columns 44 to the hub 46 of the column wheel. Thus, the guide post 44, the arm 48 and the hub 46 form a four-times rotationally symmetrical superstructure. Ratchet 42 has 12 teeth spaced 30 ° apart from each other. Thus, those skilled in the art will appreciate that the column wheel of the present example is an 12/4 stroke (three stroke) column wheel.

The perspective view of fig. 10 clearly shows the hub 46 and the arms 48 connecting the guide posts to the hub. The presence of the arm and the hub makes the overall structure of the column wheel, and in particular the column, more rigid. It is clear that a more rigid column wheel allows working with a particularly high level of accuracy. It can also be seen that the width of the arm at its narrowest point is significantly less than the width of the guide post (the width of the guide post is defined herein as the distance separating the leading edge of the guide post from the trailing edge). According to the invention, the width of the arm 48 is less than half the width of the guide post 44. In this example, the width of the arm is even about one third of the width of the guide post. This feature of the invention means that the space 45 can be provided in the superstructure of the column wheel. These spaces are necessary to allow the beaks of the pivoting members to fall sufficiently far down between the guide posts.

Fig. 10 also shows that the height of the hub 46 and arms 48 is less than the height of the guide post 44. The height of the arms is preferably between 20% and 60% of the height of the guide posts. One advantage of this feature is that it means that the stroke of the stem beak can be extended if the stem is mounted high enough to allow the stem beak to pass over the arm 48 of the column wheel. Preferably, the column wheel is manufactured entirely on a lathe. The uninterrupted manufacture on the lathe allows for a higher precision of the part.

Figure 9 clearly shows the profile of the guide post 44. It can be seen that the profile of the guide post corresponds generally to the deformed ellipse, or possibly more precisely to the profile of the aircraft wing. Thus, the front side of the column (in combination with the direction of rotation of the column wheel) is defined as the "leading edge" and the rear edge as the "trailing edge". The column also has an outer face (facing the exterior of the column wheel) and an inner face (facing the hub 46). The outer and inner faces meet at a leading edge and a trailing edge. It can be seen that with respect to the outer face, the profile of the guide post forms an arc of a circle substantially concentric with the guide post wheel. On the inner face, however, the radius of curvature of the profile of the guide post is greater in the region of the trailing edge than in the region of the leading edge (as is the case with conventional aircraft wings).

In fig. 9, in the leading edge region, the angle formed by the inner and outer faces of the guide post is defined as "α"; in the trailing edge region, the angle formed by the inner and outer faces of the guide post is defined as "β". Fig. 9 also shows that the two angles alpha and beta are in fact very rounded. The fact that the angle α is very rounded has the advantage of facilitating the advance of the beak of the bar cooperating with the guide post when the chronograph mechanism is operating. As regards the angle β, the fact that the angle is a circle has practically no technical effect, in a variant the angle β may be sharp. In the example shown, angles α and β have values of 58 degrees and 31 degrees, respectively. According to various embodiments, the angle α may vary, but is preferably between 55 and 65 degrees. The angle beta depends on the number of guide posts included in the guide post wheel, which is preferably smaller when there are more guide posts. However, the angle β is preferably between 25 and 35 degrees.

Finally, the width of the guide post 44 naturally depends on the number of guide posts included in the guide post wheel 40. However, according to the invention, the guide posts of the guide post wheel are wider than the openings provided between the guide posts.

Figures 3 to 8 are views from the rear cover side of a timepiece movement according to a particular embodiment of the invention. The timepiece movement shown is arranged to be integrated in a wristwatch. Under these conditions, the crown-pusher shown at the top of the figure is actually at three o' clock, if seen on the dial side of the wristwatch containing the movement. It is therefore evident that, since figures 3 to 8 are views from the rear cover side, the "noon" position of the watch is located on the right side of the figure, in which the time-scale ring extends in a counter-clockwise direction.

Figures 3-8 illustrate the same timing mechanism according to certain embodiments of the present invention at different stages of a complete duty cycle. In addition to the column wheel 40, the illustrated chronograph mechanism comprises a chronograph wheel 1, a pivotally coupled part 4, the oscillating pinion 2 and two springs (5 a and 5b, respectively), the pivotally coupled part 4 having a beak arranged to cooperate with the column wheel, the oscillating pinion 2 pivoting on a coupling lever 3. The coupling lever 3 is arranged to pivot in one direction or the other in order to cause the toothing of the oscillating pinion 2 to alternately mesh with the toothing of the chronograph wheel 1 or to be released from the toothing of the chronograph wheel 1. The coupling lever 3 pivots to stop and restart the chronograph mechanism. In practice, oscillating pinion 2 is permanently driven by a fourth wheel set (not shown) of the movement gear train. Under these conditions, when the chronograph wheel is engaged with the pinion 2, the chronograph wheel is driven; when the oscillating pinion is released from the toothing of the chronograph wheel, the latter is uncoupled.

The purpose of the spring 5a is to return the coupling rod and the oscillating pinion it carries against the chronograph wheel. The spring 5b is arranged to return the beak of the pivotally coupled part against the column wheel. These figures also show that, at the end opposite the beak, the pivoting coupling part 4 carries a pin 6, which pin 6 is arranged to cooperate with a corresponding end of the coupling rod 3. First, it can be seen that when the beak of the pivoting coupling part 4 is lowered between two guide posts, the pin 6 moves away from the coupling lever, as shown in particular in fig. 4 and 5. Under these conditions, there is nothing to prevent spring 5a from bringing oscillating pinion 2 into engagement with the toothing of chronograph wheel 1. Conversely, when the beak of the pivoting coupling part is lifted by the guide post of the column wheel, as shown in particular in fig. 3, the pin 6 forces the coupling lever 3 to pivot, which has the effect of moving the oscillating pinion 2 away from the toothing of the chronograph wheel. Therefore, it is the column wheel 40 that controls the coupling and decoupling of the timing wheel 1.

The illustrated chronograph mechanism also includes a minute counter wheel 15 and an intermediate wheel 12. The minute counter wheel 15 is driven by the chronograph wheel 1 via the intermediate wheel 12. It can also be seen that the arbour of the chronograph wheel and the arbour of the minute counting wheel both carry a reset heart (7 and 17, respectively). A hammer having two arms is arranged to cooperate with the two heart-pieces. The hammer is formed by a reset pivot member 10 and a movable hammer top 9 in the shape of a rudder foot rest (rudderar). The movable hammer head is hinged to one end of the pivoting member 10 and has two inclined portions 8a, 8b, the inclined portions 8a, 8b being respectively arranged to cooperate with one of the heart-pieces 7, 17. The reset pivot member 10 is arranged in a known manner to pivot in one direction to lower the hammer against the heart piece or in the other direction to raise the hammer. In the rest position, the spring 19 is arranged to return the hammer against the heart pieces 7, 17. Finally, controlling the inclination (tipping) of the hammer is also the column wheel 40.

The chronograph mechanism of the present example also comprises a brake formed by a brake lever 30, one of the ends of the brake lever 30 carrying a shoe 32, which shoe 32 is arranged to hold the chronograph wheel by acting on the outer periphery of the chronograph wheel 1. The brake lever 30 is arranged in a conventional manner to pivot alternately between a raised position, in which the shoe 32 is held away from the timing wheel, and a lowered position, in which the shoe blocks the timing wheel. In the rest position, a spring (not shown) is provided to return the shoe 32 against the chronograph wheel. Also controlling the pivoting of the brake lever 30 is the column wheel 40.

The chronograph mechanism of the present invention also comprises a mechanism for controlling the column wheel. The mechanism is a pushing mechanism. The pushing mechanism is conventionally arranged to: as the user repeatedly actuates the push button of the push mechanism, the angular position of the column wheel 40 is gradually increased. Still further, column wheel 40 is held by a column wheel jumper spring (indicated by reference numeral 50 in fig. 3 and 6) which presses against the teeth of a ratchet arrangement (indicated by reference numeral 42 in fig. 9 and 10) to hold the column wheel in a stable position.

The pushing mechanism, which in the example shown connects button 67 of crown-pusher 65 to column wheel 40, comprises pawl 52, pawl spring 54, pivoting control part 56, intermediate control lever 58 and control spring 60. In the present example, crown-pusher 65 is arranged at "3 o' clock" at the periphery of the movement and it is associated with a winding and hand-setting stem (not shown) which extends in the direction of the centre of the movement. The intermediate lever 58 pivots on the frame at "4 o ' clock" and its slightly curved shape allows it to extend substantially along the periphery of the movement over the interval between "4 o ' clock" and "2 o ' clock". The intermediate lever carries a tongue 62 at 3 o' clock, which tongue 62 faces the crown-pusher. The tongue is bent at an angle of about 90 deg. towards the dial side of the movement. Thus, the tongue forms a flag generally facing the crown-pusher. As will be seen in more detail below, the button includes a bearing surface 69, the bearing surface 69 being arranged to press against the banner so as to actuate the intermediate lever of the control mechanism when the button is actuated.

The pivoting control part 56 pivots on the frame at 1 o' clock and its slightly curved shape enables it to extend substantially along the periphery of the movement close to the crown-pusher. The control spring 60 is arranged to cooperate with the pivoting control part 56 in order to return the free end of said pivoting control part towards the periphery of the movement. It can also be seen that the free end of the pivotal control member 56 carries a stepped stud 57, which stud 57 is arranged to cooperate with the distal end of the intermediate lever 58. It is therefore evident that the stepped stud 57 allows the spring 60 to permanently push back the distal end of the intermediate lever 58 towards the outside of the movement. Obviously, conversely, when the user pivots the lever 58 by pressing the button, this also has the effect of pivoting the pivoting control member 56.

The free end of the pivot control member 56 carries a pawl (indicated by reference numeral 52) of the pivot control member in a known manner. The pawl 52 is free to pivot on the end of the pivoting control part and is returned against the ratchet toothing 42 of the column wheel by a pawl spring 54. Thus, pawl 52 is arranged to cooperate with the teeth of ratchet device 42 and, when the end of pivoting control member 56 is pivoted towards the centre of the movement as a result of pressing on the push-button, pawl 52 accompanies this movement by moving the column wheel forward by the value of one ratchet. At this point, once the depression on the push button is released, the control spring 60 returns the pivoting member 56 and the lever 58 to their rest positions. The pawl 52 also slides back on the sloped portion of the ratchet tooth. Thus, when a press is then applied on the button, the pawl is ready to actuate the next tooth.

In this example, the button must be pressed three times in a conventional manner in order to have one guide post replace the previous one, pressing three times corresponding to three timer functions: start, stop, and reset. Figure 3 shows the chronograph mechanism at rest after being reset to zero. All the elements of the chronograph mechanism are stopped, except for the oscillating pinion 2 which is permanently driven by the gear train of the watch movement (the direction of rotation of the oscillating pinion is indicated by the arrow).

Figure 4 shows the moment when the timing mechanism is activated. The button 67 of the crown-pusher is pushed in, the intermediate lever 58 and the pivoting control part 56 have pivoted towards the centre of the movement, driving the pawl 52. This movement of the pawl causes the column wheel 40 to move forward 30 deg. in a clockwise direction. The column wheel rotation of 30 has the effect of lifting the beak of the reset pivoting part 10, causing it to pivot to raise the hammer and release the heart pieces 7, 17. Furthermore, the rotation of the column wheel also has the effect of dropping the beak of the pivotal coupling part 4 down into the space between the two columns (indicated by reference numeral 44 in fig. 9 and 10). As seen above, the increment of the column wheel also causes the toothing of the oscillating pinion to mesh with the toothing of chronograph wheel 1, by allowing the pivoting coupling part to pivot in this way, thanks to the action of spring 5. Finally, a 30 ° turn has no effect on the brake, so the beak remains raised.

Figure 5 shows the timing mechanism during operation. Button 67 of crown-pusher 65 has returned to its rest position, as has intermediate lever 58 and pivoting control part 56. The pawl 52 is also returned and ready again to actuate the next tooth when the button is actuated again. The hour wheel 1, the intermediate wheel 12 and the minute counting wheel 15 are driven by the oscillating pinion 2 to rotate in the direction indicated by the arrow in the figure.

Fig. 6 shows the time when the chronograph mechanism stops. With another actuation of the crown-pusher, push button 67 is pushed in, intermediate lever 58 and pivoting control part 56 have pivoted again towards the centre of the movement, driving pawl 52 and causing column wheel to rotate again through 30 °. This new increment of the column wheel has on the one hand the effect of causing the beak of the pivoting coupling part 4 to be lifted and thus causing the release of the oscillating pinion 2 from the chronograph wheel 1. Further, the rotation of the column wheel also has the effect of dropping the beak of the brake lever 30 into the space between the two columns 44 by pivoting the brake lever. As seen above, pivoting of the lever 30 lowers the shoe 32 against the chronograph wheel 1, so that it blocks the chronograph wheel.

Fig. 7 shows the chronograph mechanism stopped. The button of crown-pusher 65 has returned to its rest position, as has intermediate lever 58 and pivoting control part 56. The pawl 52 is also returned and ready again to actuate the next tooth when the button is actuated again. The shoe 32 of the brake lever 30 holds the chronograph wheel 1 and the minute counter wheel 15 in a position in which the chronograph mechanism is stopped, allowing the time elapsed between the start and the stop of the chronograph mechanism to be read.

Figure 8 shows the moment when the timing mechanism is reset to zero. With another actuation of the crown-pusher, button 67 is pushed in, intermediate lever 58 and pivoting control part 56 having pivoted again towards the centre of the movement, driving pawl 52 and incrementing the column wheel by 30 ° again. This new increment of column wheel has the effect, on the one hand, of lifting the beak of the brake lever 30 and thus causing the shoe 32 to move away from the chronograph wheel 1. Furthermore, the rotation of the column wheel also has the effect of dropping the beak of the reset pivoting part 10 into the space between the two columns 44 and thus pivoting the reset pivoting part. The effect of the pivoting of the reset pivoting member is to lower the two inclined portions 8a and 8b of the hammer against the two heart-pieces 7, 17, respectively, in order to return the chronograph wheel 1 and the minute-counting wheel 15 to their respective starting points.

Referring again to figures 3 to 8, it should be pointed out that if the beaks of the pivoting coupling part 4 and of the reset pivoting part 10 are compared with those shown in figure 2, it is evident that the beaks of the timepiece movement according to the invention may be tapered less (more tapered) than those of the prior art. One advantage of this feature is that the tapered beak (the point of the beak forming an angle of less than 40 ° and preferably less than 30 °) allows the pivoting part of the timing mechanism of this example to fall even into the relatively narrow space formed by the gap between the two guide posts of the guide post wheel, such as shown in fig. 10. The corollary of this is that it is clear that the use of a tapered beak like the beak of the pivoting part of the chronograph mechanism in this example in turn requires a wider guide post to prevent the beak from falling off inadvertently.

Claims (7)

1. A column wheel (40) for a three-stroke chronograph mechanism, comprising:

-a ratchet device (42) provided with 3 x n teeth (n > -3);

-a central hub (46);

-an superstructure coaxial to the column wheel and presenting n rotational symmetries, comprising n radial arms (48) and n guide posts (44) parallel to the axis of rotation of the column wheel, evenly distributed along the circumference of the column wheel and spaced from each other by n empty spaces formed as a plurality of openings between the guide posts, each guide post comprising an outer face and an inner face connected to each other by a leading edge and a trailing edge, the outer face having a circular shape concentric to the axis of rotation of the column wheel, the inner face being initially connected to the hub (46) by a radial arm (48);

characterized in that the width of the guide posts (44) measured between the leading edge and the trailing edge is larger than the width of the openings between the guide posts, the width of the arm (48) at its narrowest point is less than half the width of the guide post (44), the height of the hub (46) and the arm (48) being between 20% and 60% of the height of the guide post (44), the inner face of the guide post (44) has a convex shape in cross-section over the part of the guide post that exceeds the height of the arm (48), the inner face has a radius of curvature in the region of the trailing edge which is greater than the radius of curvature in the region of the leading edge, in the region of the guide edge, the angle formed by the inner and outer faces of a guide post is between 55 and 65, in the area of the trailing edge, the angle formed by the inner and outer faces of a guide post is between 25 ° and 35 °.

2. The column wheel of claim 1, wherein n-4.

3. Chronograph mechanism comprising a column wheel (40) according to claim 1 or 2 and at least one pivoting part (4, 10, 30), the beak of which is arranged to cooperate with a guide post (44) of the column wheel.

4. A chronograph mechanism according to claim 3, characterized in that the beak of the pivoting part has a point forming an angle of less than 40 °.

5. Chronograph mechanism according to claim 4, characterized in, that the points form an angle of less than 30 °.

6. Chronograph mechanism according to claim 3, characterized in, that the pivoting part is a pivoting link part (4).

7. Chronograph mechanism according to claim 3, characterized in, that the pivoting part is a reset pivoting part (10).