Reversible screw-and-nut actuating device and sliding door equipped with such a device

A reversible-screw- (3) and-nut (14) actuating device is connected by a coupling (12, 13) to a sliding door, the screw (3) itself being connected to a motor. A carriage (11) which can move along the screw comprises a lock (16, 22, 28, 24) for locking this carriage automatically when the nut (14) reaches one end of its travel and for unlocking it automatically when the screw is moved in the opposite direction. The lock (16, 22, 28, 24) can move with respect to the nut and is stressed toward a locking position by a helical spring (29) working in the direction of its winding. A manual unlocking means comprises a plate (37) which can move about an axis (40) so as to align the locking finger (22) and its roller (28) with a slide channel (23) counter to the spring (29), this unlocking being possible even when the screw forces in the direction of closing for safety reasons, the unlocking then being validated only when the screw is released. Application to a door of a public transport vehicle. See FIG. 3.

The present invention relates to a reversible-screw-and-nut actuating 
device for maneuvering a movable element in translational movement, such 
as a leaf of a sliding door, the displacement of which can be obtained 
either automatically by means of a motor connected to the screw or 
manually, in particular in the event of an emergency, by virtue of the 
reversible nature of the screw/nut connection. 
The invention relates more particularly to the locking of such an element 
which can move in translational movement, and applies in particular to the 
locking in the closed position of a sliding door or of a pair of such 
doors which have been conjugated, such as automatically opening and/or 
closing doors of public transport vehicles, in particular railroad 
vehicles. 
FR-2,417,620 discloses a device for locking a sliding door, the leaf of 
which is connected in translational movement to a nut mounted on a 
reversible driving screw driven in rotation by a motor in order to ensure 
the opening and/or closing of the door, this nut being guided in a slide 
channel which prevents it from rotating. Furthermore, means are provided 
in order to interrupt, at the end of the travel, the guidance in 
translational movement of the nut and to permit it to rotate angularly 
with the screw so that a locking finger joined to the nut engages in a 
keeper formed on one side of the slide channel, after which the finger 
engaged in the keeper locks any translational movement of the nut and 
hence of the leaf. Such a locking is necessary because of the reversible 
nature of the screw/nut connection. 
In order to open the leaf, the direction of rotation of the screw need only 
be reversed in order to obtain, firstly, the reverse angular rotation of 
the nut which ensures the unlocking and then the translational movement of 
the nut in the direction opening the door. 
This device consequently ensures the automatic locking and unlocking 
functions. 
Means other than the motor are also provided which make it possible, from 
the locked position, to cause the nut to pivot in order to unlock it, 
following which the leaf can be pushed manually into the open position 
with rotation of the screw. This permits emergency opening, for example in 
the event of the motor breaking down. A reversible type of screw/nut 
connection has been selected in order to permit the emergency opening. 
However, the known device described above does not permit unlocking with a 
view to deferred actuation which will be termed hereinafter "anticipatory 
unlocking", which consists in enabling users to unlock the door whilst at 
the same time keeping the doors closed by supplying the motor in the 
closing mode. This makes it possible, in the event of a semi-emergency 
situation, to invite the passengers to unlock the doors before the vehicle 
has reached the intended disembarkation point, or when there is a fear of 
a breakdown but it is not known whether this breakdown will take place 
before reaching the platform. It is therefore a matter of allowing the 
passengers to get off as soon as possible, but only at the appropriate 
moment. 
Furthermore, before releasing the doors, the engineer can attract the 
attention of the passengers, for example by loudspeaker, as to what 
precaution should be taken in order to minimize the risks of an accident. 
In fact, with the known device, when the vehicle is in a situation in which 
the opening of the doors may prove dangerous, the engineer is obliged to 
place the motor permanently in the mode of closing the door and, in this 
case, the passenger cannot unlock the door since he would have to overcome 
the power of the motor transmitted in the opposite direction to the nut 
via the screw. 
The object of the present invention is a reversible-screw-and-nut actuating 
device which is inexpensive to produce, does not have the abovementioned 
disadvantage and which, in addition to the immediate unlocking of the 
door, permits its anticipatory unlocking. 
The subject of the present invention is a reversible-screw-and-nut 
actuating device for maneuvering an element such as a leaf of a sliding 
door, the device comprising a screw connected to a motor, a carriage which 
can move along the screw and is connected at least indirectly to said 
element, the carriage comprising a nut mounted on the screw, and a lock 
for locking the carriage automatically when the nut reaches one end of its 
travel and for unlocking the carriage automatically when the screw is 
moved in the direction tending to space the nut apart from said end of its 
travel, the device comprising means limiting the rotation of the nut about 
the axis of the screw, wherein the lock can move with respect to the nut 
and is stressed toward a locking position by a spring, and wherein the 
device comprises a force-transmission member connected to the nut with a 
clearance, and means which are sensitive to the relative position of the 
nut and of the force-transmission member in order to enable the spring to 
bring the lock into the locking position when the screw rotates in the 
direction stressing the nut toward said end of its travel, and in order to 
return the lock positively into an inactive position when the screw 
rotates in the opposite direction. 
The subject of the present invention is also a door with a sliding leaf, in 
particular for a railroad vehicle, comprising a leaf associated with a 
device such as that described above and means for returning the lock into 
an inactive position counter to the action of the spring and independently 
of the means which can sense the relative position of the nut and of the 
force-transmission member. 
When the carriage reaches the end of its travel, the lock passes 
automatically into the locking position under the action of the spring 
since the screw rotates in the direction stressing the nut toward said 
end. It is therefore the spring, and not the force of the screw, which has 
caused the locking and, consequently, in order to effect a "manual" 
unlocking, it is simply a matter of overcoming the force of the spring 
even if the screw is stressed in the closing direction. For automatic 
unlocking, it is simply a matter of rotating the screw in the reverse 
direction, the means which are sensitive to the relative position of the 
screw and of the force-transmission member then returning the lock 
positively into an inactive position. 
By virtue of the invention, a device is thus provided in which, on the one 
hand, the drive screw can drive the lock automatically into the locking or 
unlocking position, and with which, on the other hand, whether the motor 
is stopped or running in the closing mode, it is possible to unlock the 
door manually simply by overcoming the force of the return spring of the 
lock, it being possible for this latter force to be predetermined in order 
to permit easy manual operation. 
In other words, in the device of the invention, the lock is partially 
dissociated from the kinematic chain, and the additional function of the 
anticipatory unlocking can be fulfilled with simple and economical means.

A device according to the invention has been shown in FIGS. 1, 2, 3 and 4 
in the case of a door having a single leaf 1 which can be displaced 
between an extreme closed position indicated in solid lines, and an 
extreme open position shown in dot-dash lines. For its guidance during 
this displacement, the leaf 1 is suspended from a fixed rail 5 by two 
suspension plates 7 fixed on the upper edge of the leaf 1 and articulated 
respectively on two movable supports 8, moving along the rail 5 by means 
of wheels 8a. 
The displacement of the leaf 1 is effected by an electric motor 2 driving 
in rotation a screw 3 of axis HH' parallel to the rail 5 and on which a 
carriage 11 is mounted. The latter is prevented as a whole from rotating 
about the axis HH' and is displaced in one or other direction along the 
screw 3 according to the direction of rotation of the latter. 
The screw 3 is mounted so as to rotate on two fixed bearings 4 made 
integral with the rail 5 which is itself fixed to the frame of the door, 
not shown. 
The carriage 11 drives the leaf 1 via a coupling 13 fixed to the leaf 1 and 
linked to the carriage 11 in terms of translational movement. 
As shown in FIG. 2, the carriage 11 comprises a nut 14 which is itself 
composed of a tubular member 17 surrounding a ball bearing cage 18 to 
which it is fixed by screws 20. The ball bearings 18a of the cage 18 roll 
in the helical grooves 19 of the screw 3. At one of its axial ends, the 
tubular member 17 carries a collar 41 immobilized axially on the nut 14 
between a shoulder 42 and an elastic ring 43. The collar 41 has a 
spherical outer bearing surface 44 on which swivels a complementary 
spherical bore of a hoop 12 constituting the upper end of the coupling 13. 
Two adjacent collars are mounted on the nut 14, in a contact plane PP' 
transverse to the axis HH', a guide or anti-rotation collar 15 and a 
locking/unlocking collar 16. 
The collars 15 and 16 are mounted so as to be free to pivot on the nut 14 
about the axis HH' but are prevented from being displaced axially on the 
latter by an elastic ring 48 and a spacer 49 pressed against the collar 
41. The amplitude of the pivoting of the collars 15 and 16 with respect to 
the tubular member 17 is limited by a projection 31 welded onto the 
tubular member 17. The projection 31 is traversed by the contact plane PP' 
of the collars 15, 16. It interacts with two respective notches 33, 34, of 
identical dimensions, made on the edge of each collar adjacent to the 
plane PP' (see FIG. 3). The extreme angular positions of the locking 
collar 16, with respect to the projection 31, correspond to the positions 
of the notch 34 in which one or other of the circumferential ends 34a, 
34b, forming an abutment, is pressed circumferentially against the 
projection 31. The same applies for the extreme angular positions of the 
guide collar 15, which positions correspond to the positions of the notch 
33 in which one or other of the circumferential ends 33a, 33b of this 
notch is pressed against the projection 31. These circumferential ends are 
not visible in FIG. 3 since the notch 33 is partially hidden. The angular 
travel of each collar 15 or 16 has a same maximum value A of approximately 
one eighth of a revolution with respect to the nut 14. 
In their lower region, the collars 15, 16 carry respectively a guide finger 
21 and a locking finger 22, each carrying a roller 28 held by a screw 26 
screwed into a tapped hole made in the finger 21 or 22. Furthermore, the 
screws 26 are locked by pins 25 force-fitted into the fingers, each pin 
comprising a bent-back part 27 at its end opposite the penetrating end. 
A helical spring 29, provided so as to work in the direction of its winding 
around the axis HH', surrounds the collars 15, 16 axially between the 
fingers 21 and 22. The ends 29a and 29b of the spring are fastened to the 
fingers 21 and 22 and retained radially by the bent-back parts 27 which 
thus prevent the undesired deformation of the spring. 
The guide finger 21 constitutes a sliding piece engaged permanently, by way 
of its roller 28, in a slide channel 23 (FIGS. 1 and 3) fixed to the frame 
of the door and parallel to the screw 3. The guide finger 21 thus 
transmits, between the projection 31 joined to the nut 14 and the slide 
channel 23, the reaction force necessary to prevent the nut from rotating 
with the screw except over the angular travel A permitted by the notch 33. 
The slide channel 23 comprises two opposite and parallel bearing walls 23a 
and 23b spaced apart from each other by a distance slightly greater than 
the diameter of the rollers 28. The slide channel 23 therefore permanently 
prevents the guide collar 15 from rotating about the axis HH'. Except when 
the leaf is in the closed position, the roller 28 of the locking finger 22 
is also situated in the slide channel 23. The spring 29 stresses the 
collar 16 in rotation with respect to the collar 15 in the direction 
pressing the locking finger 22 against the wall 23b, against which the 
guide finger 21 presses when the screw rotates in the direction closing 
the leaf. The slide channel is joined, at one of its ends, and on the side 
of the wall 23b, to a keeper 24. 
When the carriage 11 reaches the end of its travel closing the leaf, the 
locking finger 22 is opposite the keeper 24 and penetrates into the latter 
by rotation of the collar 16 with respect to the collar 15, and hence with 
respect to the slide channel 23, under the action of the spring 29. The 
keeper 24 comprises two parallel walls 24a and 24b, transverse to the axis 
HH' and the mutual distance apart of which is slightly greater than the 
diameter of the roller 28. The wall 24a is joined to the wall 23a and thus 
closes the slide channel 23. The wall 24b is joined to the wall 23b. The 
walls 24a and 24b are connected by a wall 24c which closes the keeper 24 
at its circumferential end furthest from the slide channel 23. When the 
finger 22 is in the locking position, its roller 28 is situated axially 
between the walls 24a and 24b of the keeper 24, which prevents any 
significant axial movement of the carriage 11, and hence of the leaf 1. 
Manual unlocking means are furthermore provided which comprise a plate 37 
which can pivot about a fixed axis 40 oriented parallel to the axis HH' so 
as to be able to sweep the keeper 24. The plate 37 is controlled by a 
linkage 39 provided with a movable articulation 41. When the finger 22 is 
in the locking position under the action of the spring 29, if a manual 
action is exerted on the linkage 39 in the direction F (FIG. 4), the plate 
37, initially placed in between the roller 28 of the finger 22 and the 
wall 24c, pivots about the axis 40 and drives, as it moves, the finger 22 
until it comes into alignment with the slide channel 23, which causes the 
unlocking of the door. 
The operation of the door provided with the device according to the 
invention will now be described with reference to FIGS. 5 to 9 which show 
diagrammatic top views of various possible configurations of the door and 
of its locking/unlocking device. 
It is assumed, to start with, that the door is open and that the automatic 
closing operation has been triggered, this operation consisting in 
rotating the screw 3 in the direction indicated by the circular arrow (see 
FIG. 5). The fingers 21 and 22 are aligned with each other since they are 
both engaged in the slide channel 23. Their notches 33 and 34 are opposite 
each other and the projection 31, joined to the nut 14 stressed in 
rotation by the screw 3, is pressed against the ends 33b and 34b of the 
notches 33 and 34. It is therefore impossible for the nut to rotate, with 
the result that the rotation of the screw 3 causes the carriage 11 to move 
translationally in the direction of the arrow (from left to right in FIG. 
5). 
When the carriage 11 reaches the end of the closing travel (FIG. 6), the 
finger 22, integral with the collar 16, reaches the keeper 24 and pivots 
in order to be housed in the latter under the action of the spring 29. 
Given the initial position of the collar 16 with respect to the projection 
31 (see FIG. 5), the collar 16 can pivot with respect to the projection 31 
only in the same direction as the screw when the leaf closes, and this is 
why the keeper 24 extends in this direction from the slide channel 23. 
From the above automatic locking position, it is possible to carry out 
either a manual unlocking of the door (see FIG. 7) or an automatic 
unlocking (see FIG. 8). 
The manual unlocking is obtained by maneuvering the linkage 39 in the 
direction F (see FIGS. 3 and 4), which makes it possible to exert an 
action tending to cause the finger 22 to pivot counter to the action of 
the spring 29 in order to place the finger 22 in alignment again with the 
finger 21 and with the slide channel 23. 
The relative position of the projection 31 and of the notch 34 permits this 
movement since the closing process ends with a reverse movement. The 
manual unlocking position of the door is thus reached, from which it is 
possible to push the door by hand into the open position, with the screw 3 
rotating under the action of the nut 14, since the screw 3/nut 14 
interengagement is of the reversible type. 
For safety reasons, the possibility of opening the door manually should be 
controlled. This is possible by running the motor 2 in the closing mode. 
In this case, the passengers can unlock the leaf by hand, meeting no other 
resistance than that of the spring 29, since the rotation of the collar 16 
between the locking and unlocking positions takes place with respect to 
the nut 14 and hence without requiring the rotation of the screw. However, 
once the user has unlocked the door manually, he cannot open the leaf as 
long as the motor is running in the closing mode. Thus, the desired 
function, namely permitting a prior manual unlocking whilst at the same 
time allowing the engineer to control the actual opening, is perfectly 
ensured. 
Furthermore, even assuming that the motor is initially stopped, it is 
possible to effect an automatic anticipatory unlocking by a simple means 
such as the closing of an electric circuit caused by operating the 
unlocking handle of the door, the unlocking becoming effective only if the 
engineer interrupts this electric circuit by means of a switch. 
From the automatic locking position shown in FIG. 6, it is possible to 
unlock the door automatically by starting up the motor 2 driving the screw 
3, by rotation of the screw in the opening direction indicated by the 
circular arrow in FIG. 8. 
In this case, the carriage 11 is initially prevented from being displaced 
by the finger 22 engaged in the keeper 24. This is why the nut 14 and the 
projection 31 begin by pivoting by 1/8th of a revolution in the same 
direction as the screw, which is permitted by the initial position of the 
projection 31 initially in contact with the end 33b of the notch 33 of the 
collar 15 immobilized in rotation by the slide channel 23. An intermediate 
position is shown in FIG. 8, after the beginning of the pivoting movement. 
This movement causes a corresponding movement of the collar 16 since the 
projection 31 was initially pressed against the end 34a of the notch 34. 
The finger 22 is thus returned into alignment with the slide channel 23, 
the situation then being that shown in FIG. 9, in which the projection 31 
is pressed against the ends 33a and 34a of the notches of the collars 15 
and 16 which are both prevented from rotating by the slide channel 23. The 
nut 14, integral with the projection 31, with the result that the rotation 
of the screw 3 in the opening direction causes the carriage 11 to be 
displaced in the opening direction of the leaf, in the direction of the 
arrow shown in FIG. 9. 
The invention is not, of course, limited to the illustrative embodiment 
which has just been described and numerous modifications may be made to it 
without going beyond the scope of this invention. 
In the example, the force-transmission means rotate with respect to the 
nut. It would, however, also be possible to use translational means, for 
example a translational play between the nut and the drive piece of the 
leaf.