WO2005014439A1

WO2005014439A1 - A container lock for locking stacked containers to each other

Info

Publication number: WO2005014439A1
Application number: PCT/SE2004/001153
Authority: WO
Inventors: Gunnar Schlyter
Original assignee: Loxystem Aktiebolag
Priority date: 2003-08-11
Filing date: 2004-07-28
Publication date: 2005-02-17
Also published as: DK200600107A; DE112004001433T5; SE0302200D0; CN100484849C; CN1867500A; DK176701B1

Abstract

The invention relates to a container lock (1) comprising a first (2) and a second locking element (3) capable of being joined to a respective locking part (4, 5) on juxtaposed container corners and rotated so as to lockingly engage the container corners. The second locking element (3) has a shaft (6) that is translationally mounted in a housing (7) connected to the first locking element (2) such that the shaft (6) can move in the axial direction when the second locking element (3) is pressed against its respective container corner. Guides (10, 11, 12, 13) on the shaft (6) and the housing are arranged to rotate the shaft (6) when the shaft (6) moves in the axial direction such that axial movement of the shaft (6) causes rotation of the second locking element (3) relative to the housing (7). The shaft (6) having an undercut recess (14) and a locking arm (16) is arranged to engage the recess (14) and prevent rotation of the shaft (6).

Description

A CONTAINER LOCK FOR LOCKING STACKED CONTAINERS TO EACH OTHER

FIELD OF THE INVENTION

The present invention relates to a container lock or container coupling tool for locking stacked containers to each other. The container lock comprises first and second locking elements capable of being joined to respective locking parts on juxtaposed container corners and rotated to lockingly engage the container corners.

BACKGROUND OF THE INVENTION

Shipping containers for overland and marine freight handling are produced in various standard sizes. The present invention relates to a container lock for coupling shipping containers stacked one on the other. In transporting shipping containers, they are often stacked on each other. This is especially the case when the containers are transported by ship. Each container is locked to the containers immediately above and below by container locks (container coupling tools), and the top containers may be fixed to the ship deck. One kind of container lock that has been proposed is a twistlock that generally comprises a housing with a shaft joumalled through the housing and having a lug or cone on opposite ends of the shaft. The housing is located between adjacent containers and the cone-shaped lugs are locked within a respective corner casting. The lugs can be inserted through elongate slots of the container corners and then rotated to lockingly engage the container corner. Container locks or coupling tools of this kind are disclosed in, for example, US patent No. 5012560, US patent No. 6164862 and US patent No. 6334241. In US patent No. 6334241, a container lock is disclosed that has an upper and a lower locking lug. The lower locking lug is translationally mounted in a housing connected to the upper lug and has a shaft capable of limited movement in the axial direction. Between the housing and the shaft, there are guide means which permit a locking rotation of the lower lug on upward movement of the shaft. The shaft has a head with a blind bore for receiving an abutment part that forms a centring abutment for a coil spring. When the container lock is assembled, the coil spring will tension-actuate the shaft and the lower locking lug in a downward direction. In the housing, a locking device is arranged that includes spring-actuated arms that can be pivoted to a position under the head of the shaft and thereby prevent axial movement of the shaft. When the spring-actuated arms lock the shaft against axial movement, the lower lug cannot be rotated away from locking engagement with the respective container corner. To release the lug from locking engagement with a container corner, an operating rod connected to the arms is pulled out causing the arms to be spread. The operating rod can be acted upon by swinging a U-shaped member. When the container lock is in place between two juxtaposed container corners, the container lock can be opened and closed by the U- shaped member. However, lifting of the lower lug from the bottom of a container corner causes the coil spring to press the head of the shaft downwards into abutment against the spring-actuated arms and cause the operating mechanism to be friction-locked.

During unloading of shipping containers, the container locks must be unlocked such that an upper container can be lifted away from a lower container. However, it may happen that, for some reason, one or several container locks have not been unlocked when the upper container is lifted. As a result, it can happen that two containers are lifted together with each other. This can result in accidents, especially if the container lock is suddenly released in such a situation. It is also a time-consuming and difficult task to open the container locks when the shipping containers are to be unloaded. This can also make the unloading operation dangerous for the personnel responsible for the unloading.

It is an object of the present invention to provide an improved container lock for shipping containers that makes it possible to lock containers to each other. It is further an object of the invention to provide a container lock that reduces the risk that one container is lifted together with another container and suddenly released such that it falls down. It is also an object of the invention to provide a container lock that is mechanically reliable and has a small number of movable parts. Yet another object of the invention is to provide a container lock that can be opened easily in a short time.

DESCRIPTION OF THE INVENTION

The container lock according to the present invention comprises a first and a second locking element capable of being joined to respective locking parts on juxtaposed container corners and rotated so as to lockingly engage the container corner. The second locking element has a shaft that is translationally mounted in a housing connected to the first locking element such that the shaft can move in the axial direction when the second locking element is pressed against its respective container corner. Between the shaft and the housing, guides are arranged to rotate the shaft when the shaft moves in the axial direction such that axial movement of the shaft causes rotation of the second locking element relative to the housing. The shaft has an undercut recess covered by a protuberance. To lock the shaft against rotation, the container lock has a locking arm in the housing. The locking arm can be rotated towards and away from the shaft such that the locking arm can be made to engage or disengage the undercut recess when the shaft is in a first angular position and the second locking element is pressed against its respective container comer but that when the shaft is in a second angular position where the second locking element lockingly engages its respective container comer, the protuberance prevents the locking arm from being rotated away from the recess. In this position, the locking arm prevents the shaft from being rotated to an angular position where the second locking element does not engage its respective container comer.

The first and second locking elements may be lugs and the respective locking parts on the container comers can be shaped with slots into which the lugs can be passed and turned so as to lockingly engage the container comers. In a preferred embodiment, the first locking element is an upper lug and the second locking element is a lower lug. In an advantageous embodiment, the locking arm is biased towards the shaft by an elastic element in the housing. A sensor can be arranged in the housing to detect the position of the locking arm.

Preferably, an actuator in the housing is arranged to rotate the locking arm away from the undercut recess when the actuator is activated by an electronic signal. The actuator is preferably a shape memory alloy actuator. In a preferred embodiment, the housing contains a battery providing power for the actuator.

In a preferred embodiment, an elastic element in the housing is arranged to act on the shaft to urge the second locking element axially away from the housing and thereby rotate the second locking element away from the second angular position.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a container lock according to the invention ready for insertion into a slot in an overlying container comer.

Figures 2 - 4 show fixing of the container lock in the upper container and locking of the container lock in a lower container comer.

Figure 5 shows in perspective and seen from below a container lock according the invention. It should be noted that Fig. 5 shows an embodiment that is different from the embodiment of Figs. 1 - 4. Figure 6 shows in perspective the same container lock as in Fig. 5 but from a different perspective.

Figure 7 shows in greater detail a part of the container lock according to the invention.

Figure 8 shows in greater detail another part of the inventive container lock.

Figure 9 is a perspective view showing the lower locking lug with the undercut recess and the locking arm.

Figure 10 is a perspective view showing the lower locking lug from a different perspective.

Figure 11 is a schematic view from above showing the mechanism for locking the shaft against rotation.

Figure 12 is a schematic view ftom above where the locking arm has been withdrawn from the undercut recess.

Figure 13 is a schematic view from above where the locking arm is in contact with the shaft and a part of the undercut recess.

Figure 14 is a schematic view from above where the locking arm has engaged the undercut recess and is prevented from being rotated away from the recess.

Figure 15 is a schematic representation of how a container lock is inserted into a lower slot or lock groove.

Figure 16 shows the container lock of Fig. 15 when inserted and locked.

Figure 17 is a sectional view through an upper locking lug in insertion position.

Figure 18 is a sectional view as in Fig. 17 with the locking lug in turned locking position. DETAILED DESCRIPTION OF THE INVENTION

In Fig. 5 and Fig. 6, a container lock 1 is shown that comprises a first 2 and a second locking element 3. In the figures, the locking elements 2 and 3 are shown as cone- shaped lugs 2, 3 but the locking elements 2, 3 could also have a different shape. The locking elements 2, 3 are connected to a housing 7 that is shown in Fig. 5 as being composed of an upper housing part 8 and a lower housing part 9 that have been connected to each other. As best seen in Fig. 8, the first locking part 2 is integral with the upper housing part 8. The locking elements 2, 3 are capable of being joined to a respective locking part 4, 5 on juxtaposed containers and rotated so as to lockingly engage the containers. Normally, the container lock 1 will be joined to container comers but it is conceivable that it could be joined to other parts of the containers. As can be seen in Fig. 7, Fig. 9 and Fig. 10, the second locking element 3 has a shaft 6. The shaft 6 is translationally mounted in the housing 7 that is connected to the first locking element 2 such that the shaft 6 can move in the axial direction into the housing 7 or out of the housing 7. In particular, the shaft 6 will move in the axial direction when the second locking element 3 is pressed against its respective container or container comer. As can be seen in Fig. 7, Fig. 9 and Fig. 10, the shaft 6 is shaped with curved guide parts 11 and 13. As can be seen in Fig. 9 and Fig. 10, the container lock 1 also has corresponding curved guide parts 10 and 12 that can cooperate with the curved guide parts 11 and 13 on the shaft 6. The curved guide parts 10 and 12 are located on the housing 7 and are integral with the housing 7. As can be seen in for example Fig. 10, the guides or guide parts 10, 11, 12, 13 on the shaft 6 and the housing 7 are arranged to cooperate with each other to rotate the shaft 6 when the shaft 6 moves in the axial direction such that axial movement of the shaft 6 causes rotation of the second locking element 3 relative to the housing 7. For example, an upper curved guide 10 on the housing 7 cooperates with an upper curved guide 11 on the shaft 6. When the shaft 6 moves axially upwards in Fig. 10, the upper guide part 11 on the shaft will glide against the curved guide 10 on the housing 7 such that the shaft 6 is forced to rotate. As best seen in Fig. 9 and Figs. 11 - 14, the shaft 6 has an undercut recess 14 covered by a protuberance 15. The container lock 1 further has a locking arm 16 in the housing 7. As indicated in Fig. 12, the locking arm 16 has an articulation 25 such that the locking arm 16 can be rotated towards and away from the shaft 6. Thereby, the locking arm 16 can be made to engage or disengage the undercut recess 14 when the shaft 6 is in a first angular position and the second locking element 3 is pressed against its respective container or container comer as indicated in Fig. 13. In Fig. 14, a second angular position of the shaft 6 is illustrated where the second locking element 3 lockingly engages its respective container comer and the protuberance 15 that covers the undercut recess 14 prevents the locking arm 16 from being rotated away from the recess. In this position, the locking arm 16 prevents the shaft 6 from being rotated to an angular position where the second locking element 3 does not engage its respective container comer. An elastic element 22 in the housing 7 can be arranged to act on the shaft 6 to urge the second locking element 3 axially away from the housing 7 and thereby rotate the second locking element 3 away from the second angular position. In Fig. 9 and Fig. 10, the elastic element 22 is shown as a coil spring 22. One end of the coil spring 22 is connected to a part of the shaft 6 and the other end of the coil spring 22 is connected to the housing 7. When the shaft 6 is pressed into the housing 7, this axial movement of the shaft must be carried out against the force of the coil spring 22. When the shaft 6 has been pressed into the housing, the coil spring 22 will seek to force the shaft 6 downwards such that the locking elements 2, 3 are pushed away from each other.

In a preferred embodiment, the first and second locking elements 2, 3 are lugs 2, 3 and the respective locking parts 4, 5 on the container comers are shaped with slots 17, 18 into which the lugs 2, 3 can be passed and turned so as to lockingly engage the container comers. However, it is possible, at least in principle, to imagine embodiments where the first and second locking elements 2, 3 are shaped as female parts that engage male locking parts on the containers. The first locking element 2 would normally be an upper lug 2 and the second locking element 3 a lower lug 3 although it is possible to envisage embodiments where the first locking element would be a lower lug 3.

In a preferred embodiment of the invention that is best seen in Fig 9 and Figs. 11 - 14, the locking arm 16 is biased towards the shaft 6 by an elastic element 19. The elastic element 19 can be a coil spring 19 in the housing 7. In Fig. 11, the coil spring 19 is indicated as being located in the lower housing part 9. In this embodiment of the invention, the locking arm 16 is constantly urged against the shaft 6 by the coil spring 19 as indicated in Fig. 9. In the housing 7, there is an actuator 20 that is arranged to rotate the locking arm 16 away from the undercut recess 14 when the actuator 20 is activated by an electronic signal.

Preferably, the actuator 20 is a shape memory alloy actuator 20. Such a shape memory alloy actuator can comprise a set of stacked parallel conductive plates wherein each conductive plate is separated from an adjacent stacked parallel conductive plate with an insulating layer configured to provide electrical isolation between adjacent stacked parallel conductive plates and a low-friction sliding surface between adjacent plates and a set of shape memory alloy links connecting the set of stacked parallel conductive plates. The set of shape memory alloy links can generate force to produce sliding displacement along insulating layers between adjacent stacked parallel conductive plates. A suitable shape memory alloy actuator is disclosed in US patent No. 6574958 incorporated herein by reference. A shape memory alloy actuator suitable for use in the inventive container lock is sold under the name "Nanomuscle actuator" and can be obtained from Nanomuscle Inc. in Antioch, CA, United States of America.

As indicated in Fig. 11, the housing 7 can advantageously contain a battery 21 providing power for the actuator 20, especially if the actuator 20 is a shape memory alloy actuator.

As indicated in Fig. 10, Fig. 11 and Fig. 12, a sensor 23 can be arranged in the housing 7 to detect the position of the locking arm 16.

The function of the inventive container lock 1 will now be explained with reference to Figs. 1 - 4 and Figs. 15 - 16. In Fig. 1, the container lock 1 is shown beneath a container part or container comer 4 with a slot 17. The container lock 1 will then be moved against the container comer 4 such that an upper locking lug 2 is inserted through the slot 17. The upper locking lug 2 is shaped with recesses 27 (see Fig. 5) such that, after insertion through the slot 17, it can be rotated as indicated by the arrow in Fig.2. When the container lock 1 and the upper locking lug 2 have been rotated, the upper locking lug 2 lockingly engages the container part or container comer 4. It is now impossible to remove the container lock from the container comer 4, unless the container lock 1 is first rotated back again. The upper container together with the container lock 1 can then be lowered and placed on a lower container as indicated in

Fig.3. The lower container has a container part or container comer 5 with a slot 18. The lower locking lug 3 will now be inserted through the slot 18 as indicated in Fig.3 and in Fig. 15. When the lower locking lug 3 is inserted through the slot 18, it will eventually reach an abutment preventing the lug 3 from continuing its movement downwards. The lower locking lug 3 and its shaft 6 will now be pressed axially into the housing 7 of the container lock against the force of the spring 22 that is connected to the shaft 6 and the housing 7. When the shaft 6 moves axially in the housing 7, the guides 10, 11, 12, 13 will cooperate with each other and force the shaft 6 to rotate. As a consequence, the lower lug 3 that is integral with the shaft 6 will be rotated as indicated in Fig. 4 and Fig. 16 to an angular position where the lower lug 3 is locked to the container part 5 or container comer 5. The two containers are now locked to each other. When the shaft 6 is rotated, the undercut recess 14 on the shaft 6 will come to a position where it can be engaged by the locking arm 16 as indicated in Fig. 13. If, for some reason, the shaft 6 should now be rotated in the opposite direction, the shaft 6 can only make a short rotation before it is stopped by the locking arm 16 from doing this as indicated in Fig.14. In this position, the locking arm 16 is also prevented by the protuberance 15 from being rotated back to a position where is does not prevent rotation of the shaft 6.

To prevent the housing 7 from being rotated relative to the lower container comer 5, the lower housing part 9 has a guide part 26 that fits the slot 18 of the container comer 5 of the lower container. The guide part 26 cooperates with the slot 18 to prevent the housing 7 from being rotated.

It should be noted that Figs. 5 and 6 show an embodiment that differs from the embodiment of Figs. 1 - 4. The difference is the following. In Figs. 1 - 4, the upper lug

2 is shaped in such a way that it will lock to the upper container comer 4 when it is rotated counter-clockwise as indicated in Fig. 2. In this respect, the lug 2 of Figs. 5 and 6 is a mirror-image of the lug 2 shown in Figs. 1 - 4 since the upper lug shown in Figs. 5 and 6 is shaped in such a way that it will lock to the upper container comer 4 when it is rotated clock-wise. Otherwise, there is no substantial difference between the two embodiments.

When the upper container shall be lifted away from the lower container during unloading, the actuator 20 is activated to pull the locking arm 16 away from the shaft 6 against the force of the spring 19. This can only be done when the upper container is still standing on the lower container such that the lower lug 3 is pressed against the lower container as indicated in Fig. 16 and the shaft 6 is in the angular position indicated in Fig. 13. If, for some reason, someone attempts to lift the upper container before the container lock 1 has been removed, the following will happen. The lower lug

3 will no longer be pressed directly against the lower container. As a result, the shaft 6 will make a short axial movement caused by the spring 22, The shaft 6 will make a short rotation until it reaches the position indicated in Fig. 14. In this position, further rotation of the shaft 6 will be prevented by the locking arm 16 and the locking arm 16 is locked in its position by the protuberance 15. In this position, the lower locking lug 3 will lockingly engage the container comer 4 since it has still not rotated to a position where it can be removed through the slot 18.

The normal unloading procedure is as follows. Firstly, a signal is generated that activates the actuator 20. The actuator 20 pulls the locking arm 16 away from the shaft 6. On the locking arm 16, there is a lip 24 that will contact a sensor 23 when the locking arm has been rotated away from the shaft 6 as indicated in Fig. 11. When the lip 24 contacts the sensor 23, a signal may be generated that indicates that the upper container can be lifted. When the upper container is lifted, the lower lug 3 is rotated since the spring 22 will push the shaft 6 downwards as soon as the lower lug 3 is no longer pressed against the lower container comer 5. The lower lug 3 can then be passed through the slot 18 in the container comer 5 and the container lock 1 can disengage the lower container.

In one embodiment of the invention, the lock 1 is provided with means for counteracting rotation of the upper locking lug 2 when it is locked to the upper container comer 4. To prevent the upper locking lug 2 from being too easily rotated away from locking engagement with the upper container comer 4, the upper locking lug 2 may be provided with ball and grove locking pins as indicated in Figs. 17 and 18. In the upper locking lug 2, there are through bores 29 into that open into the recesses 27. Pins 28 are placed in the bores 29 and are held in position in a well known way by a spring-loaded ball-and-groove arrangement. As indicated in Fig. 17 and 18, the pins 28 have grooves 30 that can receive a ball 31. The ball 31 is actuated by a spring 32 and a nut 33 in a way that is known for ball-and-groove locking pins. This kind of locking arrangement is also described in US patent No. 6,334,241.

The invention confers the advantage that, if an upper container is lifted before the container lock has been removed, the container lock cannot be disconnected while the lower container is still suspended from the upper container. An additional advantage is that the sensor will indicate when the lower lug can be disconnected. Yet another advantage is that the number of movable parts is small which reduces the risk of malfunctioning. Since all movable parts can be located inside the housing, the risk that salt or ice will disturb the function of the container lock is not so great.

If a shape memory alloy actuator is used for moving the locking arm, the need for electrical power is small. This means that a large number of openings can be achieved without change of battery.

Claims

1. A container lock (1) comprising a first (2) and a second locking element (3) capable of being joined to a respective locking part (4, 5) on juxtaposed container comers and rotated so as to lockingly engage the container comer, the second locking element (3) having a shaft (6) that is translationally mounted in a housing (7) connected to the first locking element (2) such that the shaft (6) can move in the axial direction when the second locking element (3) is pressed against its respective container comer, guides (10, 11, 12, 13) on the shaft (6) and the housing arranged to rotate the shaft (6) when the shaft (6) moves in the axial direction such that axial movement of the shaft (6) causes rotation of the second locking element (3) relative to the housing (7), the shaft (6) having an undercut recess (14) covered by a protuberance (15), the container lock (1) further having a locking arm (16) in the housing (7) that can be rotated towards and away from the shaft (6) such that the locking arm (16) can be made to engage or disengage the undercut recess when the shaft (6) is in a first angular position and the second locking element (3) is pressed against its respective container comer but that when the shaft (6) is in a second angular position where the second locking element (3) lockingly engages its respective container comer, the protuberance (15) prevents the locking arm (16) from being rotated away from the recess and the locking arm (16) prevents the shaft (6) from being rotated to an angular position where the second locking element (3) does not engage its respective container comer.

2. A container lock according to claim 1, characterised in that the first and second locking elements (2, 3) are lugs (2, 3) and in that the respective locking parts (4, 5) on the container comers are shaped with slots (17, 18) into which the lugs (2, 3) can be passed and turned so as to lockingly engage the container comers.

3. A container lock according to claim 1 , characterised in that the locking arm (16) is biased towards the shaft (6) by an elastic element (19) in the housing (7).

4. A container lock according to claim 3, characterised in that an actuator (20) in the housing (7) is arranged to rotate the locking arm (16) away from the undercut recess (14) when the actuator (20) is activated by an electronic signal.

5. A container lock according to claim 4, characterised in that the actuator (20) is a shape memory alloy actuator (20).

6. A container lock according to claim 5, characterised in that the housing (7) contains a battery providing power for the actuator (20).

7. A container lock according to claim 2, characterised in that the first locking element (2) is an upper lug (2) and the second locking element (3) is a lower lug (3).

8. A container lock according to any of claims 1 - 6, characterised in that an elastic element (22) in the housing (7) is arranged to act on the shaft (6) to urge the second locking element (3) axially away from the housing (7) and thereby rotate the second locking element (3) away from the second angular position.

9. A container lock according to any of claims 1 - 6, characterised in that a sensor (23) is arranged in the housing (7) to detect the position of the locking arm (16).