Information
-
Patent Grant
-
6802645
-
Patent Number
6,802,645
-
Date Filed
Tuesday, May 20, 200321 years ago
-
Date Issued
Tuesday, October 12, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 368 124
- 368 125
- 368 169
- 074 15
- 074 84 R
- 074 435
- 074 437
-
International Classifications
-
Abstract
The escapement (1) arranged between a motor gear train and a roller (2) to which is attached a sprung balance of a timekeeper, the balance being able to describe an arc of free oscillation and to receive oscillation maintaining impulses, this escapement including first (3) and second (4) toothed wheels meshing with each other, one of these wheels being driven by the motor gear train and a rocking member (5) having:first (41) and second (42) contact means able to receive impulses generated alternately by the first (3) and second (4) wheels,impulse means (11, 12) capable of co-operating with the roller (2) to transmit said impulses to said roller to drive it in rotation and to maintain the oscillations of the balance,and first (43) and second (44) blocking means for alternately blocking said first (3) and second (4) wheels after each impulse transmitted by said impulse means to said roller,said first and second contact means and said first and second blocking means being arranged at the periphery of the rocking member in regions remote from each other.
Description
The present invention relates to an escapement arranged between a motor gear train and a roller to which there is attached the balance of a timekeeper, the balance being able to describe an arc of free oscillation and to receive oscillation maintaining impulses, this escapement including first and second toothed wheels meshing with each other, one of these wheels being driven by the gear train.
The Applicant of the present invention has already proposed an escapement that partly answers the definition that has just been given and a description of which is given in European Patent document No. 01200043.6, incorporated herein by reference. This document describes an escapement shown in
FIG. 1
, arranged, as is usual, between a gear train and a roller
2
supporting a sprung balance of a timekeeper. The sprung balance, not shown in the Figure, is able, as is known, to move through an arc of free oscillation and is arranged to receive impulses for maintaining these oscillations. By definition, the gear train, also called the train, is the set of wheels and pinions which, from a barrel, transmits the driving force to an escapement wheel. In
FIG. 1
, the gear train is represented by its last wheel
30
, associated with pinion
31
. Wheel
30
drives a first escapement wheel
3
via pinion
32
which is fixed thereto. First wheel
3
meshes with a second wheel
4
. Wheels
3
and
4
have the same diameter and the same number of teeth.
The escapement also includes a rocking member
5
able to receive impulses generated alternatively by the first and second escapement wheels
3
and
4
. Rocking member
5
, in turn, transmits the impulses received to roller
2
to drive it in rotation so as to maintain the oscillations of the sprung balance fixed to said roller
2
. Moreover, the rocking member is arranged to block alternately the first and second escapement wheels
3
and
4
, after each impulse has been transmitted to roller
2
.
Rocking member
5
fitted to the escapement is supported by an arbour
6
freely pivoting in a plate (not shown) comprised in the timekeeper. This rocking member
5
has a substantially triangular shape. A first apex of the rocking member defines an edge
19
on which a tooth
8
of first wheel
3
can rest to subject rocking member
5
to an impulse in a first direction. A second apex of the rocking member defines another edge
19
on which a tooth
10
of the second wheel
4
can rest to subject rocking member
5
to an impulse in a second direction B, opposite to the first direction. Edges
19
of the rocking member are connected by a rim
14
allowing first
3
and second
4
wheels to be blocked alternately, in proximity to the edges, after each transmitted impulse. Finally, a third apex of rocking member
5
comprises two teeth
11
and
12
capable of meshing with a tooth
13
of roller
2
.
Each of teeth
8
,
10
of wheels
3
and
4
has a front flank
16
comprising a first curved summit cut out portion
17
capable of abutting against rim
14
of the rocking member to block one of the wheels, and a second cut out portion
18
in the shape of an arc of circle, following the first cut out portion, capable of abutting against one of edges
19
to drive rocking member
5
in rotation.
It is an object of the present invention, which takes up the features disclosed in the aforecited document, namely two wheels meshing with one another, one of the wheels being driven by the gear train, to provide a timekeeper escapement having improved chronometric performances.
For this purpose, the escapement of the present invention thus further includes a rocking member having:
first and second contact means able to receive impulses generated alternately by the first and second wheels,
impulse means capable of co-operating with the roller to transmit said impulses to said roller to drive it in rotation and to maintain the oscillations of the balance,
and first and second blocking means for blocking alternately said first and second wheels after each impulse transmitted by said impulse means to said roller,
said first and second contact means and said first and second blocking means being arranged at the periphery of the rocking member in regions remote from each other.
According to a preferred embodiment of the invention, this rocking member is supported by an arbour pivoting freely in a plate of the timekeeper and the impulse means comprise first and second teeth capable of meshing with a tooth of the roller. It advantageously has a substantially symmetrical shape with respect to an axis passing between said first and second teeth of the rocking member and through the centre of the arbour, wherein:
the first and second contact means are arranged symmetrically with respect to said axis,
and the first and second blocking means are arranged symmetrically with respect to said axis.
Thus, the rocking member of the invention not only allows the angle of lift to be reduced, which allows the chronometric performance to be improved, but also the impulse speed to be increased by selecting the leverage. Indeed, the introduction, in the present invention, of a rocking member comprising contact means (and associated impulse) and blocking means separated from and set apart from each other and co-operating with a tooth of the other wheel allows:
the number of teeth of the escapement wheels to be increased,
the distance between the centre of the roller and the rocking member to be varied, and
the angle of attack of one tooth of the first wheel or respectively the second wheel on respectively the first and second contact means to be optimised, at the time of an impulse.
As a result, on the one hand, the peripheral speed of the rocking member impulse means can be selected so as to be greater than that of the contact means and, on the other hand, the force transmitted by the teeth of the first and second escapement wheels on the rocking member is substantially perpendicular to the radius passing through the rotational axis of the rocking member and the point of contact of the teeth on the rocking member, which allows maximum transmission of the drive torque.
The invention will now be explained in detail hereinafter via an embodiment given by way of example, this embodiment being illustrated by the annexed drawings, in which:
FIG. 1
, which has already been described, is a plan view of the escapement according to the prior art;
FIGS. 2
to
7
are plan views of the escapement according to the invention shown at six different stages describing one complete oscillation of the balance.
FIGS. 2
to
7
are plan views of six successive phases of the escapement of the invention, these phases covering one complete oscillation of the sprung balance. The escapement shown in these successive Figures differs from the escapement of the prior art in the structure of the rocking member
5
used as well as in the shape of teeth
8
and
10
of escapement wheels
3
and
4
. The other elements, common to the two escapements, have already been described in FIG.
1
.
As
FIG. 2
shows, rocking member
5
fitted to the escapement according to the invention is supported by an arbour
6
freely pivoting in a plate (not shown) of the timekeeper. This rocking member
5
includes first and second contact means respectively formed by first
41
and second
42
edges able to receive impulses generated alternately by the first
3
and second
4
wheels. It also includes impulse means comprising first and second teeth
11
and
12
capable of meshing with a tooth
13
of a roller
2
for transmitting these impulses to the roller to drive it in rotation and to maintain the oscillations of the balance.
It will be noted in this regard that roller
2
includes a lower plate
2
a
provided with tooth
13
and an upper plate
2
b
having a substantially smaller diameter provided with a notch
46
in the shape of an arc of circle opening onto tooth
13
the function of which will be explained hereinafter.
It further includes first and second blocking means formed by first
43
and second
44
blocking faces for alternately blocking the first
3
and second
4
wheels after each transmitted impulse. It is to be noted that the first
41
and second
42
edges and the first
43
and second
44
blocking faces are arranged at the periphery of rocking member
5
in regions remote from each other.
This rocking member
5
preferably has a substantially symmetrical shape with respect to an axis (X—X) passing between the first and second teeth
11
and
12
of the rocking member and through the centre of arbour
6
. The first and second contact means are arranged symmetrically with respect to this axis (X—X) as well as the first and second blocking means.
It is to be noted that the angle (a) formed by the segment connecting the first contact means to the centre of the arbour and the segment connecting the second contact means to the centre of the arbour, is an acute angle preferably comprised between 50° and 70°. This angle (a), shown in
FIG. 2
, is advantageously equal to 60°.
It is also to be noted that the angle (b) formed by the segment connecting the first blocking means to the centre of the arbour and the segment connecting the second blocking means to the centre of the arbour, is an obtuse angle preferably comprised between 130° and 170°. This angle (b), shown in
FIG. 3
, is advantageously equal to 155°.
The first edge
41
forming the first contact means, co-operates with the end of a tooth
8
of the first wheel
3
to subject rocking member
5
to an impulse in a first direction (B) (see FIG.
3
). The second edge
42
forming the second contact means, co-operates with the end of a tooth
10
of the second wheel
4
to subject rocking member
5
to an impulse in a second direction (A), opposite to the first direction (B) (see FIG.
7
).
The first blocking face
43
co-operates with the end of a tooth
8
of wheel
3
, next to tooth
8
that was previously used to subject the rocking member to an impulse in direction B, to block the rocking member (see FIG.
4
). The second blocking face
44
co-operates with the end of a tooth
10
of wheel
4
, next to tooth
10
that was previously used to subject the rocking member to an impulse in direction A, to block the rocking member.
It will also be observed that each of teeth
8
,
10
of respectively first
3
and second
4
wheels has a front flank
16
comprising a curved cut out portion
21
capable of co-operating respectively with the first
43
and second
44
blocking faces of the rocking member to block one of the wheels, and also capable of abutting respectively against the first
41
and second
42
edges of the rocking member to drive the rocking member in rotation.
Since it is important to avoid rocking member
5
overbanking (due for example to a shock) during the travel of the free oscillation arc of the balance and thus of roller
2
to which it is attached, there is provided a small tongue
45
preferably having one end ending in a point, placed in a parallel plane to that into which teeth
11
and
12
of the rocking member extend. Thus, during the free oscillation arc, small tongue
45
prevent rocking member
5
overbanking for example in the event of a shock by the latter being blocked at the periphery
20
of upper plate
2
b.
Finally, it will be understood that it is important to limit the angular excursion of rocking member
5
. Two pins
25
and
26
, driven into the timekeeper plate, will be used for this purpose. Teeth
11
and
12
of rocking member
5
abut against the pins as shown in
FIGS. 2 and 4
, thus limiting the excursion of the rocking member.
As a preferred embodiment of the new escapement has been described hereinbefore as well as the functions fulfilled by the various parts forming it, its actual operating mode will now be reviewed by describing one complete working cycle.
FIGS. 2
to
7
, which show six important phases of this cycle, will be examined in turn.
First Phase (FIG.
2
)
The mechanism is stopped. The second escapement wheel
4
is blocked since the curved cut out portion
21
of its tooth
10
is in contact with the second blocking face
44
of rocking member
5
. The angular excursion of rocking member
5
is at the end of its travel since its tooth
12
is stopped against pin
26
. At this moment the sprung balance is close to the end of oscillation (arrow E) or close to the end of the second vibration of this oscillation. Tooth
13
of plate
2
enters into contact with tooth
11
of rocking member
5
and will drive said rocking member in the direction of arrow B. This is a rocking member release phase where, on the one hand tooth
12
is driven so as to move away from pin
26
and, on the other hand, the second rocking member blocking face
44
can move aside curved cut out portion
21
of tooth
10
.
Second Phase (FIG.
3
)
Rocking member
5
continues its travel in the direction of arrow B, driven as it is by roller
2
. At this moment, tooth
13
of the roller is totally engaged-between the two teeth
11
and
12
of rocking member
5
. It will be noted that notch
46
of upper plate
2
b
allows, in this position, the passage of small tongue
45
and thus the rotation of rocking member
5
. Curved cut out portion
21
of tooth
8
a
of the first wheel enters into contact with the first edge
41
of the rocking member. Escapement wheel
4
is then driven in the direction of arrow F via escapement wheel
3
, which rotates in the direction of arrow G driven as it is in turn by the gear train the last element
30
of which is shown in FIG.
1
. This is an impulse phase that moves the roller in the direction of arrow E and causes the rocking member to rotate in the direction of arrow B until the first rocking member blocking face
43
meets the curved cut out portion of tooth
8
b
of the first escapement wheel, next to tooth
8
a
in the opposite rotational direction of wheel
3
.
Third Phase (FIG.
4
)
When tooth
13
of roller
2
leaves tooth
12
of the rocking member, the first rocking member blocking face
43
abuts against the curved cut out portion
21
of the neighbouring tooth
8
b
of the first escapement wheel
3
thus blocking the first and second wheels. From this moment roller
2
begins a second oscillation in the direction of arrow E. The rocking member is then held by tooth
11
, which abuts against pin
25
.
Fourth Phase (FIG.
5
)
The situation of rocking member
5
is the same as that described hereinbefore with the only difference that small tongue
45
prevents any overbanking. Roller
2
continues to rotate in the direction of arrow E and covers the first vibration of its second free oscillation. Rocking member
5
and the first and second wheels
3
and
4
are still blocked.
Fifth Phase (FIG.
6
)
After having travelled through its first vibration, roller
2
returns in the opposite direction shown by arrow M and travels through the second vibration of its second free oscillation. Rocking member
5
still blocks the first and second wheels and is still prevented from overbanking owing to small tongue
45
.
Sixth Phase (FIG.
7
)
Tooth
13
of roller
2
enters into contact with tooth
12
of rocking member
5
, which will drive the latter in the direction of arrow A. We are in a similar situation here to that illustrated by
FIG. 1
, i.e. at the beginning of a new release phase where, on the one hand tooth
11
is driven so as to move away from pin
25
and, on the other hand the first rocking member blocking face
43
can be moved aside curved cut out portion
21
of tooth
8
of first wheel
3
and which will allow
10
a
of second wheel
4
to abut on the second edge
42
of rocking member
5
to move roller
2
again. From this sixth phase a new cycle similar to that which has been described starts again, the next blockage acting on second escapement wheel
4
via wheel
10
b
, next to wheel
10
a
in the opposite rotational direction of wheel
4
, on second rocking member blocking face
44
.
Final Considerations
It will be noted that the first and second escapement wheels have a structure allowing more teeth to be arranged at their periphery, thus the torque necessary to drive the barrel is smaller and thus the energy consumed is lower.
Claims
- 1. An escapement arranged between a motor gear train and a roller to which is attached a sprung balance of a timekeeper, the balance being able to describe an arc of free oscillation and to receive oscillation maintaining impulses, this escapement including first and second toothed wheels meshing with each other, one of these wheels being driven by the motor gear train and a rocking member comprising:first and second contact means able to receive impulses generated alternately by the first and second wheels, impulse means capable of co-operating with the roller to transmit said impulses to said roller to drive it in rotation and to maintain the oscillations of the balance, and first and second blocking means for alternately blocking said first and second wheels after each impulse transmitted by said impulse means to said roller, said first and second contact means and said first and second blocking means being arranged at the periphery of the rocking member in regions remote from each other.
- 2. The escapement according to claim 1, wherein the rocking member is supported by an arbour pivoting freely in a plate of the timekeeper, wherein said impulse means include first and second teeth capable of meshing with a tooth of the roller, wherein said rocking member has a substantially symmetrical shape with respect to an axis passing between said first and second teeth of the rocking member and through the centre of the arbour, whereinthe first and second contact means are arranged symmetrically with respect to said axis, and the first and second blocking means are arranged symmetrically with respect to said axis.
- 3. The escapement according to claim 1, whereinthe first contact means co-operate with an end of a tooth of the first wheel to subject the rocking member to an impulse in a first direction, the second contact means co-operate with an end of a tooth of the second wheel to subject the rocking member to an impulse in a second direction, opposite to the first direction, and the first and second blocking means co-operate with an end of a neighbouring tooth respectively of the first and second wheels to block the rocking member.
- 4. The escapement according to claim 1, wherein the first and second contact means are formed respectively by first and second edges and wherein the first and second blocking means are formed respectively by first and second blocking faces.
- 5. The escapement according to claim 4, wherein each of the teeth respectively of the first and second wheels has a front flank including a curved cut out portion capable of abutting respectively against the first and second blocking faces of the rocking member to block one of said wheels, and also capable of abutting respectively against the first and second edges of the rocking member to drive the rocking member in rotation.
- 6. The escapement according to claim 2, wherein a first segment connecting the first contact means and the centre of the arbour and a second segment connecting the second contact means and the centre of the arbour form an acute angle preferably comprised between 50° and 70°.
- 7. The escapement according to claim 2, wherein a first segment connecting the first blocking means and the centre of the arbour and a second segment connecting the second blocking means and the centre of the arbour form an obtuse angle preferably comprised between 130° and 170°.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 02077092 |
May 2002 |
EP |
|
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|
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|
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|
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A |
|
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|
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| Number |
Date |
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