EP1841681A1

EP1841681A1 - Elevator car door locking apparatus

Info

Publication number: EP1841681A1
Application number: EP05704395A
Authority: EP
Inventors: Lidewij C. Van Wagensveld; Kensuke Imajou
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2005-01-28
Filing date: 2005-01-28
Publication date: 2007-10-10
Anticipated expiration: 2025-01-28
Also published as: CN100542934C; EP1841681A4; WO2006080093A1; CN1960935A; EP1841681B1

Abstract

This invention provides a car door locking apparatus which is capable of retaining a lock element in a locked position in case of a power failure with a car positioned outside a landing zone, and which takes car inclination and installation into account and is independent of a door drive. This invention is equipped with a cam which, when the car is outside the landing zone, moves together with a bracket into engagement with a guide surface, thereby generating a drive force for moving a latch from a locked position to an unlocked position, and an actuator which, during car travel, moves the cam to a retracted position not in engagement with the guide surface. The shape of the cam is constructed such that the drive force is generated during cam motion by a prescribed quantity and that the drive force is maintained during cam motion beyond the prescribed quantity.

Description

DESCRIPTION

ELEVATOR CAR DOOR LOCKING APPARATUS

[Technical Field]

In normal operation, elevator doors are automatically opened by a door drive usually located on the elevator car. In case that the car stops between floors, e.g., due to a power failure, passengers force the car doors manually to open. A car door locking apparatus is therefore required to prevent this type of manual opening. The present invention relates to an elevator car door locking apparatus to lock the door outside a landing zone, independent of the door drive and with taking into account some possible car inclination due to eccentric car loading. [Background Art]

There are many car door locking apparatuses operated by the door drive or the door coupling mechanism motion. There is such a disadvantage that these car door locking apparatuses can not be applied to already existing door drives or door coupling mechanisms without modification. Also, installation tolerances become stricter due to the combination of a plurality of functions in one mechanism.

For example, a car door locking apparatus that is not dependent on the door drive or door coupling mechanism is described in Patent GB 2206331.

As shown in Fig. 14, the first conventional car door locking apparatus described in Patent GB 2206331 is composed of lever mechanisms 8 and 10, an electrically operated actuator 13, and stationary guide surfaces 12 in the hoistway, which are combined to generate three possible lock element positions.

As the actuator 13 pulls a lever 9 upward, a lock element 5 pivots clockwise about a pivot point A to a first locked position where a latch 7 engages with a pin 4. This disables opening operations of doors 1 and 2. Further, when the actuator 13 is not activated, the lever 9 moves downward due to the force of gravity, causing the lock element 5 to rotate counterclockwise about the pivot point A to a second locked position where a latch 6 engages with a pin 3. This disables opening operations of the doors 1 and 2. Further, in the case where the guide surface 12 is present, the roller 11 comes into contact with the guide surface 12, and the linked lever mechanism of the levers 8 and 10 causes the lock element 5 to be held in an unlocked position where the latches 6 and 7 are spaced away from the pins 3 and 4 by the distance 1. This enables opening operations of the doors 1 and 2.

For example, a similar car door locking apparatus is also described in Patent US 4934488.

As shown in Fig. 15, the second conventional car door locking apparatus described in Patent US 4934488 is composed of a lever mechanism 17, an electrically operated actuator 18, and stationary guide surfaces 19 in a hoistway, which are combined to generate three possible lock element positions.

A lock element 16, which is equipped with a roller 17a and has a lever 17b linked thereto, is rotated by the electrically operated actuator 18 away from the guide surface 19 to a first locked position C where an upper protrusion 16c restricts the movement of a restriction element 15. When the actuator 18 is not activated, the lock element 16 rotates to a second locked position B where a lower protrusion 16d restricts the movement of the restriction element 15. Then, when the roller 17a comes into contact with the guide surface 19, the lock element 16 rotates from the second locked position B to the unlocked position A. For control during car travel, the actuator 18 is caused to remain energized from the start of car travel until immediately before the car arrives at a predetermined designated floor, the actuator 18 being de-energized immediately prior to the arrival at the designated floor.

In the first conventional car door locking apparatus, in case of a power failure with the car positioned outside the landing zone, the lock element 5 rotates from the first locked position to the second locked position via the unlocked position. So, in case that the doors 1 and 2 are opened in between floors during a power failure, there is always a short moment that the lock element 5 is unlocked before it reaches the second locked position.

In the second conventional car door locking apparatus, in case of a power failure with the car positioned outside the landing zone, the lock element 16 rotates from the first locked position C to the second locked position B via the unlocked position A. So in case that the doors are opened in between floors during a power failure, there is always a short moment that the lock element 16 is unlocked before it reaches the second locked position B.

Car inclination may occur due to eccentric car loading and the always present clearances or flexibilities in the car guiding. For car door locking apparatuses using a mechanism on the car including a roller that may contact guide surfaces in the hoistway, car inclination in the direction towards the guide surfaces directly influences the amount of motion of the roller. Also the installation tolerances of the guide surfaces directly influence the possible roller motion. In the first and second conventional car door locking apparatuses mentioned above, car inclination and installation tolerances will result in a different lock element rotation. As a result, the lock element rotation may vary and is related to the floor and the actual car load. This increases the level of possible lock malfunctioning. [Disclosure of the Invention]

An object of the present invention is to provide a car door locking apparatus in which a lock element is adapted to assume two states of a locked position and an unlocked position, the lock element being capable of retaining the locked position even in case of a power failure with a car positioned outside a landing zone, and which takes car inclination and installation into consideration and is independent of a door drive.

This invention relates to an elevator car door locking apparatus for locking a sliding door of an elevator car when the car is not in a landing zone, the elevator car door locking apparatus including: a guide surface mounted in a hoistway at each landing; and a lock mechanism portion mounted to the car. The lock mechanism portion includes^: a support fixedly mounted to the car; a lock element mounted to the support and adapted to move between a locked position where the lock element is positioned inside a motion path of the door to restrict an opening operation of the door and an unlocked position where the lock element is positioned outside the motion path of the door to enable the opening operation of the door,' and an actuation portion mounted to the support and adapted to be movable toward and away from the guide surface, the actuation portion being, during travel of the car, in a retracted position away from the guide surface to keep the lock element in the locked position and being, upon arrival of the car at a landing, in an actuation position in engagement with the guide surface and moving away from the guide surface to move the lock element from the locked position to the unlocked position. Further, the actuation portion is constructed such that when the actuation portion is in the actuation position, motion of the actuation portion away from the guide surface by a prescribed quantity complete motion of the lock element to the unlocked position, and motion of the actuation portion beyond the prescribed quantity causes the unlocked position of the lock element to be maintained.

According to this invention, the lock element assumes the locked position during car operation and assumes the unlocked position upon car arrival at a landing. The locked position is thus retained even in the event of a power failure during car operation. Further, the unlocked position of the lock element is maintained during motion of the actuation portion beyond a prescribed quantity. Accordingly, by setting the prescribed quantity as the motion of the actuation portion corresponding to the worst condition of car inclination and installation tolerances, the car inclination and installation tolerances do not have any effect on the unlocked position of the lock element. [Brief Description of the Drawings] Fig. 1 is a perspective view, as seen from the landing side, of an elevator car door locking apparatus according to an embodiment of the present invention.

Fig. 2 is a perspective view, as seen from the car side, of an elevator car door locking apparatus according to an embodiment of the present invention.

Fig. 3 is a side view showing an unlocked position inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention.

Fig. 4 is a view for explaining an activated state of an actuator inside a landing zone in an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 5 is a view for explaining a non-activated state of an actuator inside a landing zone in an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 6 is a view for explaining an activated state of a cam inside a landing zone in an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 7 is a view for explaining a non-activated state of an actuator outside a landing zone in an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 8 is a front view showing an unlocked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 9 is a side view, as seen from the bracket side, showing an unlocked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 10 is a rear view showing an unlocked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention! Fig. 11 is a side view, as seen from the support board side, showing an unlocked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention;

Fig. 12 is an enlarged side view of the vicinity of a cam, for explaining a locked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention!

Fig. 13 is an enlarged side view of the vicinity of a cam, for explaining an unlocked state inside a landing zone of an elevator car door locking apparatus according to an embodiment of the present invention;

Fig. 14 is a structural view schematically showing an example of a conventional elevator car door locking apparatus,' and

Fig. 15 is a structural view schematically showing another example of a conventional elevator car door locking apparatus. [Best Mode for carrying out the Invention]

Hereinbelow, the basic concept and operation of the present invention are described by way of an embodiment of the invention with reference to the drawings.

Figs. 1 and 2 show an embodiment of an elevator car door locking apparatus of the present invention from two different view points. A car door locking apparatus 22 is composed of a locking mechanism portion 23 attached to the car, and guide surfaces 24 which are mounted in a hoistway at each landing position. Although the locking mechanism portion 23 is positioned underneath the car sill 20 in this embodiment, the present invention is not limited only to this position. Further, the guide surfaces 24 are static mounted in the hoistway at each landing. The car locking apparatus 22 prevents a sliding door 21 from opening unless the locking mechanism portion 23 is positioned opposite the guide surface 24 and an electromagnetically operated actuator 38 of the locking mechanism portion 23 is not activated or powered.

Next, the locking mechanism portion 23 will be explained in more detail with reference to Fig. 3.

A support 27 includes a long support arm 27A and a support board 27B formed integrally with the other end side of the support arm 27A. The upper end of the support arm 27A extends above the car sill 20 and the lower end side thereof is suspended below the car sill 20, the support arm 27A being static mounted to a car frame (not shown). Further, the support board 27B extends from one side of the support arm 27A, with the direction of its plane being vertical.

A latch 25 serving as a lock element is mounted to the upper end of the support arm 27A so as to be rotatable about a hinge point 26. In the horizontal position (locked position) shown, the latch 25 is positioned in the door 21 motion path so that the door 21 can not be opened. Further, in the maximum rotated position (unlocked position), the latch 25 is moved out of the door 21 motion path and the door 21 can be opened. Note that the center of mass of the latch 25 is to be always positioned between the car door 21 and the hinge point 26.

A vertically extending slotted hole 30 is bored in the support board 27B in proximity to the support arm 27A. Further, a shaft element 29 is fitted in and guided inside the slotted groove 30 so as to be vertically movable.

One end of a wire or rod 28 is connected to the latch 25 eccentrically from the hinge point 26 and the other end thereof is connected to the shaft element 29. Downward movement of the shaft element 29 as it is guided inside the slotted hole 30 pulls the wire or rod 28 downward. This causes the latch 25 to rotate counterclockwise about the hinge point 26 shown in Fig. 3 to move out of the door 21 motion path, thus releasing the lock on the door 21. Note that other than the above-described example, other vertical guides may be applied instead of the shaft element 29 inside the slotted hole 30.

A bracket 37 is mounted to the support 27 so as to be horizontally movable. In the shown example, a guide rail 36 is mounted to the support board 27B, with the longitudinal direction of the guide rail 36 being horizontal. Further, three rollers 35 are mounted to the bracket 37 so as to be rotatable about the horizontal axis. The bracket 37 is mounted to the support board 27B with two rollers 35 put on the guide rail 36 from above and the remaining one roller 35 applied onto the guide rail

36 from below. This construction enables the bracket 37 to move toward and away from the guide surface 24. While the horizontal guide here is composed of the guide rail 36 mounted to the support board 27B and the three rollers 35 mounted to the bracket 37, other guide systems can be applied instead as well.

A cam 32 is mounted to and moved along with the bracket 37. As will be described below, the cam 32 includes an inclined part 32a in sloping downward toward the guide surface 24, with the inclined part 32a contacting the shaft element 29. Here, if the cam 32 moves away from the guide surface 24 along with the motion of the bracket 37, it results in a downward motion of the shaft element 29. This downward motion of the shaft element 29 results in a pulling force to the wire or rod 28.

Next, the driving mechanism of the bracket 37 will be described.

An electromagnetically operated actuator 38 is mounted to bracket 37. Further, the lever 33 is fixed to a driving shaft 38a of the actuator 38. Further, a roller 31 is rotatably mounted to the free end of a lever 33.

The actuator 38 is able to rotate the lever 33 from the horizontal position over a certain angle when activated. Rotation of the lever 33 results in a certain gap between the roller 31 and the guide surface 24. By this gap no contact between the roller 31 and the guide surfaces 24 occurs during car travel. A return spring (not shown) makes sure that in case that the actuator is not activated or powered, the lever 33 returns to and is kept in the horizontal position. In this case there will be some overlap in position of the guide surface 24, if present, and the roller 31. If the car is not in the landing zone, the lever 33 with the linked roller 31 can rotate freely to the horizontal position. The bracket 37 remains in the default position. However, in case that the car is in the landing zone, the roller 31 contacts the guide surface 24 before the lever 33 reaches the horizontal position. The only way that the lever 33 can continue to rotate to the horizontal position is when the bracket 37 moves away from the guide surface 24.

A spring 39 is installed in order to urge the bracket 37 in the direction of the guide surface 24 and applied between the bracket 37 and the support board 27B to ensure that the bracket 37 returns to the default position after the actuator 38 rotates the lever 33 along with the roller 31 away from the guide surface 24.

A rubber stopper 34, which serves to determine the default position of the bracket 37, is mounted to the bracket 37. As the bracket 37 moves toward the guide surface 24 due to the urging force of the spring 39, the stopper 34 comes into contact with the support board 27B, stopping the movement of the bracket 37. The bracket 37 is thus retained in the default position.

Here, the rope or rod 28, the shaft element 29, the roller 31, the cam 32, the bracket 37, the actuator 38, etc. constitute an actuation portion of the lock mechanism portion 23.

Operation of the actuator 38 is described next with reference to Figs. 4 through 7.

Fig. 4 shows the actuator 38 in the activated state. When the actuator 38 is activated, the lever 33 is rotated away from the guide surface 24 together with the roller 31 linked to the lever 33. This rotation of the lever 33 causes the roller 31 to be positioned at a retracted position with a certain gap between the roller 31 and the guide surface 24. This prevents generation of noise and vibration resulting from the roller 31 coming into contact with the guide surface 24 as the car passes landings during car travel.

In Fig. 5, the car is in the landing zone and the actuator 38 is shown in a non-activated state. The lever 33 will rotate to the horizontal position by gravity force and return spring force. However, due to the presence of the guide surface 24, the roller 31 will contact the guide surface 24 before the lever 33 reaches the horizontal position. Further, as shown in Fig. 6, the lever 33 continuously rotates until reaching the horizontal position, causing a reaction force from the guide surface 24 to the roller 31. The reaction force is transferred to the bracket 37, moving the bracket 37 away from the guide surface 24. A requirement is that the force to move the bracket 37 away from the guide surface 24 is smaller than the force to rotate the lever 33 to the horizontal position. As described above, the roller 31 is positioned at an actuation position in engagement with the guide surface 24, and the cam 32 linked to the bracket 37 is moved along with the bracket 37 and away from the guide surface 24. The door 21 is then unlocked.

Fig. 7 shows what happens if the actuator 38 is not active in case that the car is not in the landing zone. In that case, the lever 33 can rotate freely to the horizontal position without the roller 31 contacting the guide surface 24. Therefore, since the guide surface 24 does not generate a reaction force, the bracket 37 is not forced to move and remains in the default position. The door 21 will remain locked.

Figs 8 through 11 show examples of the locking apparatus 22 in the unlocked position when the car is in the landing zone. In this case, the actuator 38 is not activated. Here, the lever 33 with the linked roller 31 is rotated to the horizontal position and the guide surface 24 generates a reaction force against the roller 31, causing the bracket 37 with the linked cam 32 to move away from the guide surface 24. The bracket 37 is horizontally guided by the support 27 (support board 27b). Here, the spring 39 positioned between the bracket 37 and the support 27 is compressed by the motion of the bracket 37. The force of the spring 39 is sufficient to return the bracket 37 to the default position as soon as the roller 31 comes out of contact with the guide surface 24. The force of the spring 39 is less than the force to keep the lever 33 in the horizontal position, so at least less than the force of the return spring of the actuator 38. By the motion of the cam 32 which is gradually distanced from the guide surface 24, the shaft element 29 is guided down inside the slotted hole 30. The displacement of the shaft element 29 pulls the wire or rod 28 down and rotates the latch 25 around hinge point 26. As a result, the latch 25 is rotated out of the motion path of the door 21, and the door 21 is no longer locked. In other words, in the case that the car is in the landing area, the latch 25 is held at the unlocked position and the door 21 can be opened.

Note that other vertical guide systems may also be applied instead of the slotted hole 30.

The rotation of the latch 25 has two extreme positions! A) a rotation angle (locked position) to lock the door 21 and B) a rotation angle (unlocked position) to unlock the door 21. The maximum rotation angle for unlocking the door 21 shall be limited for several reasons. The first reason is that the latch 25 is protruding too much from the car sill line in case it rotates over a too big angle. Thus there is a fear that infringement with parts of the landing door equipment may occur. The second reason is that the center of mass of the latch 25 shall always be positioned between the car door 21 and the hinge point 26 to ensure that the latch 25 is always locked by gravity in case the wire or rod 28 is broken. To limit the maximum rotation angle of the latch 25, the shaft element 29 motion shall be limited as well. Again, the shaft element 29 motion depends on the shape of the cam 32.

Now, the relationship between the cam 32 and the shaft element 29 is described in more detail based on Figs. 12 and 13.

The cam 32 is composed of the inclined part 32a and the horizontal part 32b. As shown in Figs. 12 and 13, the lower surface of the inclined part 32a is formed as an inclined surface sloping downward toward the guide surface 24. Further, the lower surface of the horizontal part 32b is formed as a horizontal surface extending horizontally from the lower end of the lower surface of the inclined part 32a toward the guide surface 24. When the shaft element 29 is in contact with the inclined part 32a, the shaft element 29 slides on the lower surface of the inclined part 32a while being guided inside the slotted groove 30 and changing its vertical position as the cam 32 moves. A drive force for moving the latch 25 from the locked position to the unlocked position is generated at this time. Further, when the shaft element 29 is in contact with the horizontal part 32b, the shaft element 29 slides on the lower surface of the horizontal part 32b as the cam 32 moves, without the shaft element 29 changing its vertical position. At this time, the drive force for moving the latch 25 from the locked position to the unlocked position is maintained.

This shape is chosen because the motion of the bracket 37 varies within a certain range dependent on the car inclination and installation tolerances. Car inclination and installation tolerances directly influence the overlap distance between the roller 31 and the guide surface 24 and therefore the possible displacement of the bracket 37 for keeping the lever 33 horizontal. During contact of the shaft element 29 with the lower surface of the inclined part 32a of the cam 32, the latch 25 is rotated to a specified maximum rotation angle. The shape of the cam 32 is designed such that the length and angle of the lower surface of the inclined part 32a is sufficient to rotate the latch 25 to the maximum rotation angle in the worst case condition of car inclination and installation tolerances. In that case. the cam 32 will move over the smallest distance (prescribed quantity). On the other hand, the cam 32 will move over bigger distances in all conditions other than this worst case combination of car inclination and installation tolerances. During this continued motion of the cam 32, the shaft element 29 will follow the lower surface of the horizontal portion 32b of the cam 32, so that the latch 25 will be held in the maximum rotated position.

In Fig. 12, the cam 32 is still in the default position. The shaft element 29 is in the upper position and contacts the lower surface of the inclined part 32a of the cam 32. The wire or rod 28 is not pulled, so the latch 25 is still in the locked position. In Fig. 13, the cam 32 moves away from the guide surface 24 over the smallest possible distance (prescribed quantity) due to the worst case combination of car inclination and installation tolerances. In this case, the shaft element 29 is moved down along the lower surface of the inclined part 32a of the cam 32 until it reaches the lower surface of the horizontal part 32b of the cam 32, causing the latch 25 to complete its movement to the maximum rotated position. The cam 32 will move away from the guide surface 24 over bigger distances in all conditions other than this worst case combination of car inclination and installation tolerances. During continued motion of the cam 32 over the smallest possible distance, the shaft element 29 will follow the lower surface of the horizontal part 32b of the cam 32. However, the wire or rod 28 is not pulled down any further, so the latch 25 is kept in the maximum rotated position as it is.

While in the described example the shaft element 29 directly slides on the lower surface of the inclined part 32a and the horizontal part 32b of the cam 32, it is also possible to fit rollers on the shaft element 29, the shaft element 29 moving along the lower surface of the inclined part 32a and the horizontal part 32b of the cam 32 while rotating the rollers. In this case, the frictional force and contact wear, which result from movement of the shaft element 29 in conjunction with movement of the cam 32, can be reduced.

With the locking apparatus 22 constructed as described above, the actuator 38 remains energized from the start of car travel until immediately before the car arrives at a predetermined designated floor, and is de-energized at a time immediately before the car arrival at the floor. As shown in Fig. 4, a gap is produced between the roller 31 and the guide surface 24 during the car travel, thereby preventing noise and vibration from being generated due to contact between the roller 31 and the guide surface 24. At this time the latch 25 is retained at the locked position, disabling opening operation of the door 21. Further, when, as shown in Fig. 6, the car arrives at the floor, the cam 32 moves away from the guide surface 24 together with the bracket 37, causing the latch 25 to move from the locked position to the unlocked position. This effects the opening/closing operation of the door 21. Further, as shown in Fig. 7, in the event of a power failure with the car positioned outside the landing zone, the lever 33 rotates to the horizontal position. Since the guiding surface 24 is not present in this case, the latch 25 is retained at the unlocked position without the cam 32 moving away from the guide surface 24 together with the bracket 37. This prevents the door 21 from being manually opened during a power failure.

Further, the locking apparatus 22 is independent of the door drive, making it applicable to existing elevators without modifications to existing door drives or door coupling mechanisms.

Further, the cam 32 is composed of the inclined part 32a and the horizontal part 32b. The length and angle of the lower surface of the inclined part 32a are designed such that the shaft element 29 is positioned at the lower end of the lower surface of the inclined part 32a when, under the worst case condition of car inclination and installation tolerances, the cam 32 is moved together with the bracket 37 to rotate the latch 25 from the locked position to the unlocked position (maximum rotated position). The latch 25 can thus be rotated to the maximum rotated position even in the worst case condition of car inclination and installation tolerances. The maximum cam 32 motion in all conditions other than this worst case combination of car inclination and installation tolerances is greater than the maximum cam 32 motion in the worst case combination of car inclination and installation tolerances. However, the increased maximum cam 32 motion results in the movement of the shaft element 29 from the inclined part 32a to the horizontal part 32b, after which the shaft element 29 moves along the horizontal part 32b, thus maintaining the maximum rotated position of the latch 25. Accordingly, car inclination and installation tolerances do not influence the maximum rotated position of the latch 25, thereby preventing the latch 25 from protruding too much from the car sill line which may cause infringement with parts of landing door equipment.

Further, the center of mass of the latch 25 is to be always positioned between the car door 21 and the hinge point 26. This allows the latch 25 to always rotate to the locked position by gravity to ensure the locked state in case the wire or rod 28 is broken. Note that there may be added a spring for urging the latch 25 from the unlocked position to the locked position.

In the locking apparatus constructed as described above, with the exception of the guide surfaces 24, the whole locking apparatus 22 can be assembled in a factory. The locking apparatus 22 can be simply installed to the car through connection with a few bolts at the job-site while standing in the pit. The guide surfaces 24 can be mounted at each landing by means of a guide surface bracket including slots for adjustability. These brackets can be installed already to the landing door support frame in a factory. The position of the guide surface 24 at the lowest landing can be adjusted at the job-site while standing in the pit. The position of the guide surface 24 is used as the reference for the guide surface 24 positions of the other landings, e.g., by use of a piano wire. The guide surface 24 position accuracy in door motion direction is less high due to the sufficient width of the guide surface 24.

Consequently, the advantages achievable by this invention include the following:

-Independent of the door drive;

-Independent of the car height;

-Independent of the type of door panel;

"Proper lock functioning even in case of a power failure or in case of car inclination; and

-Easy to install at the job-site.

Claims

1. An elevator car door locking apparatus for locking a sliding door of an elevator car when the car is not in a landing zone, comprising: a guide surface mounted in a hoistway at each landing; and a lock mechanism portion mounted to the car, the elevator car door locking apparatus being characterized in that: the lock mechanism portion comprises: a support fixedly mounted to the car; a lock element mounted to the support and adapted to move between a locked position where the lock element is positioned inside a motion path of the door to restrict an opening operation of the door and an unlocked position where the lock element is positioned outside the motion path of the door to enable the opening operation of the door,^' and an actuation portion mounted to the support and adapted to be movable toward and away from the guide surface, the actuation portion being, during travel of the car, in a retracted position away from the guide surface to keep the lock element in the locked position and being, upon arrival of the car at a landing, in an actuation position in engagement with the guide surface and moving away from the guide surface to move the lock element from the locked position to the unlocked position; wherein the actuation portion is constructed such that when the actuation portion is in the actuation position, motion of the actuation portion away from the guide surface by a prescribed quantity complete motion of the lock element to the unlocked position, and motion of the actuation portion beyond the prescribed quantity causes the unlocked position of the lock element to be maintained.

2. An elevator car door locking apparatus according to Claim 1, characterized in that the actuation portion comprises a bracket mounted to the support and adapted to be movable toward and away from the guide surface, and a roller disposed on the bracket and adapted to move the bracket away from the guide surface while in contact with the guide surface.

3. An elevator car door locking apparatus according to Claim 2, characterized in that the actuation portion comprises an electromagnetically operated actuator which, when energized, moves the roller from the actuation position to the retracted position.

4. An elevator car door locking apparatus according to Claim 2, characterized in that: the actuation portion comprises a part mechanically coupled to the lock element, and a cam which is mounted to the bracket so as to contact the part and which, upon arrival of the car at a landing, moves together with the bracket to generate in the part a drive force for moving the lock element from the locked position to the unlocked position! wherein the cam is formed in a shape which allows the drive force to be generated in the part during motion of the cam by the prescribed quantity and which allows the drive force to be maintained during motion of the cam beyond the prescribed quantity.

5. An elevator car door locking apparatus according to Claim 4, characterized in that the lock element is coupled to the part by a wire.

6. An elevator car door locking apparatus according to Claim 4, characterized in that the lock element is coupled to the part by a rod.

7. An elevator car door locking apparatus according to Claim 4, characterized in that the cam comprises an inclined part and a horizontal part, wherein during motion of the cam by the prescribed quantity, the part follows the inclined part to generate the drive force, moving the lock element from the locked position to the unlocked position, and during subsequent motion of the cam beyond the prescribed quantity, the part follows the horizontal part to maintain the drive force, maintaining the lock member in the unlocked position.