SYSTEM AND A METHOD FOR HARVESTING ENERGY FROM A CONTAINER HANDLING VEHICLE

Abstract

A container-handling vehicle for handling storage containers in a three-dimensional grid of an underlying storage system, comprising: at least one lifting device for lifting storage containers from and lowering storage containers to the underlying storage system, said lifting device comprises a lifting frame for gripping a storage container, a winch system for lifting and lowering the lifting frame, a motor to drive the winch system and a driver circuit with a controller controlling the motor; and at least first and second rechargeable power sources for providing power to the motor, wherein the driver circuit further comprises a regenerative energy circuit configured to harvest energy from the motor when the lifting frame is lowered into the storage system and where the driver circuit is configured to direct harvested energy to the rechargeable power sources according to levels of charge in the rechargeable power sources.

Claims

1. A container-handling vehicle configured to move on a rail system arranged in a grid pattern across a top of a three-dimensional grid of an underlying storage system configured to store a plurality of stacks of storage container, wherein the rail system comprising a first set of parallel rails arranged in a horizontal plane (P) extending in a first direction (X) across the top of the three-dimension grid, and a second set of parallel rails arranged in the horizontal plane (P) and extending in a second direction (Y) which is orthogonal to the first direction (X), which first and second sets of rails form a grid pattern in the horizontal plane (P) comprising a plurality of adjacent grid cells, the container-handling vehicle comprising: at least one lifting device for lifting storage containers from and lowering storage containers to the underlying storage system, said lifting device comprises a lifting frame for gripping a storage container, a winch system for lifting and lowering the lifting frame, a motor to drive the winch system and a driver circuit with a controller controlling the motor; and at least first and second rechargeable power sources for providing power to the motor, wherein the driver circuit further comprises a regenerative energy circuit configured to harvest energy from the motor when the lifting frame is lowered into the storage system and wherein the driver circuit is configured to control and direct harvested energy to the first and/or second rechargeable power sources according to preset levels of charge in the first and second rechargeable power sources.

2. The container-handling vehicle according to claim 1, wherein the first rechargeable power source is a Li-ion battery, and the second rechargeable power source is a capacitor.

3. The container-handling vehicle according to claim 1, wherein the driver circuit is further connected to charge sensors connected to the first and/or second rechargeable power sources.

4. The container-handling vehicle according to claim 2, wherein said driver circuit is configured to direct the energy harvested by the regenerative energy circuit to the at least one capacitor if the rechargeable battery is greater than 75% of a full charge level.

5. The container-handling vehicle according claim 2, wherein said driver circuit is configured to direct the energy harvested by the regenerative energy circuit to the rechargeable battery if the rechargeable battery is below 75% of a full charge level.

6. The container-handling vehicle according claim 2, wherein said driver circuit is configured to direct the energy harvested by the regenerative energy circuit to the rechargeable battery and to the at least one capacitor if both rechargeable power sources is below 50% of a full charge level.

7. The container-handling vehicle according to claim 1, where the regenerative energy circuit further is configured to harvest energy from motors driving the wheels of the container-handling vehicle for generating energy when the container-handling vehicle decelerates.

8. The container-handling vehicle according to claim 2, wherein said at least one capacitor is a capacitor using electrochemical and/or electrostatically charge storage.

9. A method for harvesting energy when a container-handling vehicle is moving on a rail system arranged in a grid pattern across a top of a three-dimensional grid of an underlying storage system configured to store a plurality of stacks of storage container, the rail system comprising a first set of parallel rails arranged in a horizontal plane (P) extending in a first direction (X) across the top of the three-dimension grid, and a second set of parallel rails arranged in the horizontal plane (P) and extending in a second direction (Y) which is orthogonal to the first direction (X), which first and second sets of rails form a grid pattern in the horizontal plane (P) comprising a plurality of adjacent grid cells. wherein said vehicle comprises a vehicle body with at least a first set of wheels for moving the container-handling vehicle in a first direction (X), at least first and second rechargeable power sources, a driver circuit for controlling the charging level of the first and second rechargeable power sources, at least one lifting device for lifting storage containers from and lowering storage containers to the underlying storage system, wherein said lifting device comprises a lifting frame for gripping a storage container, a winch system for lifting and lowering the lifting frame, a motor to drive the winch system and a driver circuit with a controller controlling the motor (407); the method comprises: connecting the motor and the regenerative energy circuit to the lifting device; lowering the lifting device into the underlaying storage system, directing generated energy to the first and/or second rechargeable power sources by means of the driver circuit.

10. The method according to claim 9, by directing the energy harvested by the regenerative energy circuit to the capacitor if the rechargeable battery is at a full current charging level.

11. The method according to claim 9, by directing the energy harvested by the regenerative energy circuit to the rechargeable battery if the rechargeable battery is below 75% of a full charge level.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where:

[0037] FIG. 1 is a perspective view of a grid of a prior art automated storage and retrieval system.

[0038] FIG. 2 is a perspective view of a prior art container handling vehicle having a centrally arranged cavity for containing storage containers therein.

[0039] FIG. 3 is a perspective view of a prior art container handling vehicle having a cantilever for containing storage containers underneath.

[0040] FIG. 4 is a box drawing of how the different parts of the system are connected according to a preferred embodiment of the present invention.

[0041] FIG. 5 is a flow chart of a process, according to an embodiment of the present invention, wherein the generated energy is directed to either of the rechargeable power sources depending on preset capacity levels.

[0042] FIG. 6 is a flow chart of a process, according to an embodiment of the present invention, wherein the generated energy is directed to the capacitor if the rechargeable battery is at 100% of its current charging level.

DETAILED DESCRIPTION

[0043] In the following, the invention will be discussed in more detail with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted.

[0044] A typical prior art automated storage and retrieval system with a framework structure 100 was described in the background section above.

[0045] The container handling vehicle rail system 108 allows the container handling vehicles 201 to move horizontally between different grid locations, where each grid location is associated with a grid cell.

[0046] In FIG. 1, the storage grid 104 is shown with a height of eight grid cells. It is understood, however, that the storage grid 104 can in principle be of any size. The storage grid 104 can be considerably wider and/or longer than disclosed in FIG. 1. For example, the grid 104 may have a horizontal extent of more than 700×700 storage columns 105. Also, the grid 104 can be considerably deeper than disclosed in FIG. 1. For example, the storage grid 104 may be more than twelve grid cells deep, i.e. in the Z direction indicated in FIG. 1.

[0047] The container vehicles 201 can be of any type known in the art, e.g. any one of the automated container handling vehicles disclosed in WO2014/090684 A1, in NO317366 or in WO2015/193278A1. The method and control system for controlling said prior art system is well known.

[0048] FIG. 2 is a perspective view of a prior art container handling vehicle having a centrally arranged cavity for containing storage containers therein.

[0049] FIG. 3 is a perspective view of a prior art container handling vehicle having a cantilever for containing storage containers underneath.

[0050] FIG. 4 is a box drawing of how the different parts of the system are connected according to a preferred embodiment of the present invention. The motor 407 and regenerative charging circuit for harvesting the energy harvests energy due to regenerative braking. In the present invention, regenerative braking can occur when the lifting frame is lowered down. Due to the weight of the lifting frame, both with or without a container attached, gravity will pull the lifting frame down without the motor 407 doing any work. Hence kinetic energy is generated from the change in potential energy. The kinetic energy from the lifting frame being lowered into the underlying storage system forces the rotor of the electric motor 407 to rotate. This rotation allows the electric motor 407 to work as a generator. The motor 407 can now harvest energy by converting the kinetic energy of the rotor into electrical energy. This electrical energy can again be stored in the rechargeable power sources.

[0051] A driver circuit 404 with a controller attached controls the motor 407. This driver circuit 404 further comprises a regenerative energy circuit 403. This regenerative energy circuit 403 is configured to harvest the electric energy generated by the motor 407. Further the driver circuit 404 directs the harvested energy to either the first or the second rechargeable power sources according to the levels of charge in the rechargeable power sources. To keep track of the charge levels of the rechargeable power sources a charge sensor 401, 402 is attached to the first and the second rechargeable power source 405, 406. The charge sensor 401, 402 communicates the charge level of the first and the second rechargeable power source 406 to the driver circuit 404.

[0052] In a preferred embodiment of the present invention the first rechargeable power source 405 can be a rechargeable battery 405. The rechargeable battery 405 can be a Li-ion battery. The second rechargeable power source 406 can be a capacitor 406. The capacitor 406 can be a supercapacitor.

[0053] Any other type of rechargeable battery and capacitor can be used.

[0054] FIG. 5 is a flow chart of a process, according to an embodiment of the present invention, wherein the harvested energy is directed to either of the rechargeable power sources depending on algorithms determining when to charge the Li-ion battery and when to charge the capacitor.

[0055] The driver circuit 404 comprises a regenerative energy circuit 403. The regenerative energy circuit 403 harvests energy from the motor during regenerative braking.

[0056] A charge sensor 401, 402 is connected to either of the rechargeable power sources 405, 406. The charge sensor 401, 402 reads of the charge level of the power sources 405, 406. This information is communicated to the driver circuit 404.

[0057] In an embodiment of the present invention a drop-off charging station is a charging station where the container handling vehicle places discharged batteries. A pick-up charging station is a charging station where the container handling vehicle picks up charged batteries.

[0058] Based on the information transmitted to the driver circuit 404 from the charge sensors 401, 402 and information on how far it is to the closest drop-off charging station and the closest pick-up charging station and the next operational task, the harvested energy is transmitted to either the first or the second rechargeable power source to ensure that the container handling vehicle has sufficient power to either perform the next operational task or drive to a charging station. Alternatively, harvested energy can be split between the two rechargeable power sources.

[0059] An algorithm determining if the harvested energy is to be sent to either the first or the second rechargeable power source is in one embodiment based on preset charging levels of the first and second rechargeable power sources.

[0060] In an embodiment of the present invention the decision to direct the harvested energy to either the battery or the capacitor or both is based on information received by the driver circuit. The information is gathered from the charge sensors attached to either of the rechargeable power sources. The charge sensors deliver information of what charge level the two power sources are at. The main object of the system is to ensure that the Li-ion battery is not overcharged or damaged through charging it too much too fast, risking fire or explosions. However, there is a further object which is to ensure that the battery has enough power to get the container handling vehicle to the drop-off charging station and that the capacitor has enough energy to ensure that the container handling vehicle can get from the drop-off charging station to the pick-up charging station.

[0061] In order to make these decisions, the container handling vehicle always needs to know the charge level of the two rechargeable power sources, the distance to the closest drop-off charging station, and the distance to the closest pick-up charging station and the next task of operation. Other information used in the algorithm may include how far it is to the next pick-up point of a container and how far it is between the pick-up point and the drop-off point of the container, as well as how deep the container handling vehicle needs to dig and the weight of the container that needs to be lifted and transported.

[0062] The information regarding the charging level of the rechargeable batteries is provided by the charge sensors connected to both the Li-ion battery and the capacitor. The information regarding the closest drop-off charging station and the closest pick-up charging station is provided to the container handling vehicle by a central computer system through e.g. Wi-Fi communication. The information regarding the next task of operation is also provided by the central computer system.

[0063] The central computer system transmits information regarding the next task of operation and the container handling vehicles calculates, based on the given information and the information gathered by the charge sensors, if it can take on the next task. If a container handling vehicle can take on the next task it communicates to the central computer system that it takes the next task of operation. If, however it cannot take on the next task of operation it communicates to the central computer system that it needs to change battery.

[0064] If a container handling vehicle has too low charge level on the battery to handle the next task of operation, but has high charge level on the capacitor, the container handling vehicle makes the decision to change the battery.

[0065] Alternatively, the container handling vehicle can use the capacitor to charge the battery if that ensures that the battery has enough power to complete the task, and the harvested energy from the lowering of the lifting frame can be used to charge the capacitor.

[0066] If the container handling vehicle has low charge level on the capacitor but high charge level on the battery the container handling vehicle can direct the energy harvested from the lowering of the lifting frame to the capacitor. Alternatively, the battery can be used to top up the capacitor.

[0067] If the container handling vehicle has high charge level on the battery and high charge level of the capacitor the harvested energy can be divided between the two rechargeable power sources. The division of how much is to be sent to the battery and how much is to be sent to the capacitor is made on current charge levels of the individual power sources. In an embodiment of the present invention the charge level of the battery should be kept within the range of 25%-75% of full charging level.

[0068] If the charge level of the battery is below 25% of the full charging capacity, the battery can be changed, or the harvested energy can be directed to the battery in order to make sure that the battery stays within its best working range. If the charge level of the battery is within 25%-75% of the full charging capacity the harvested energy can be directed to the battery in order to keep it within its best working range. If the charge level of the battery is above 75% of the full charging level the harvested energy can be sent to the capacitor.

[0069] Alternatively, if the charge levels of the two rechargeable power sources are at their full current charging level the container handling vehicle can decide to not harvest the energy generated from the lowering of the lifting frame.

[0070] If the container handling vehicle has low charge on battery and low charge on capacitor, the container handling vehicle will ensure that the capacitor has enough energy to maneuver from one charge point to another. Alternatively, the battery can be used to fully charge the capacitor if the battery has enough power left to ensure that it can manoeuvre the container handling vehicle to the closest drop-off charging station.

[0071] The purpose is to ensure that the combined power of the two rechargeable power sources always has enough power to transport the container handling vehicle to the closest drop-off charging station and from the closest drop-off charging station to the closest pick-up charging station.

[0072] The rules for when to charge the rechargeable battery and when to charge the capacitor stated above is not meant to be exclusive, but an example of a set of rules. Other rules can be used and are within the scope of the invention.

[0073] FIG. 6 is a flow chart of a process, according to an embodiment of the present invention, wherein the harvested energy is directed to the capacitor 406 if the rechargeable battery 405 is at 100% of its current charging level.

[0074] As stated earlier if a Li-ion battery is overcharged, lithium ions can build up on the anode as metallic lithium, this is called lithium plating. Lithium plating degrades the battery's lifetime and durability. It can also lead to a short circuit which again might lead to a fire.

[0075] Hence in order to avoid the buildup of lithium plating, a safety measure is built into the system. If the battery is in danger of being overcharged the driver circuit 404 directs the harvested energy to the capacitor 406.

[0076] The battery is fully charged when it is at 100% of its current charging level. To overcharge it would be to try and charge the battery when it is at 100% of its current charge level. A battery's charging level may drop during its life time. However, 100% of its current charging level is to be considered as the maximum level of charge it can hold on any given time.

[0077] In an embodiment of the present invention the battery can be used to charge the capacitor 406 if the charge level of the capacitor 406 is lower than the set level for transporting the container handling vehicle between one charging station to the other.

LIST OF REFERENCE NUMBERS

[0078] Prior Art (FIGS. 1-4):

[0079] 1 Prior art automated storage and retrieval system

[0080] 100 Framework structure

[0081] 102 Upright members of framework structure

[0082] 103 Horizontal members of framework structure

[0083] 104 Storage grid

[0084] 105 Storage column

[0085] 106 Storage container

[0086] 106′ Particular position of storage container

[0087] 107 Stack

[0088] 108 Rail system

[0089] 110 Parallel rails in first direction (X)

[0090] 110a First rail in first direction (X)

[0091] 110b Second rail in first direction (X)

[0092] 111 Parallel rail in second direction (Y)

[0093] 111a First rail of second direction (Y)

[0094] 111b Second rail of second direction (Y)

[0095] 112 Access opening

[0096] 119 First port column

[0097] 120 Second port column

[0098] 201 Prior art storage container vehicle

[0099] 201a Vehicle body of the storage container vehicle 201

[0100] 201b Drive means/wheel arrangement, first direction (X)

[0101] 201c Drive means/wheel arrangement, second direction (Y)

[0102] 301 Prior art cantilever storage container vehicle

[0103] 301a Vehicle body of the storage container vehicle 301

[0104] 301b Drive means in first direction (X)

[0105] 301c Drive means in second direction (Y)

[0106] 304 Gripping device

[0107] 500 Control system

[0108] 401 Charge sensor

[0109] 402 Charge sensor

[0110] 403 Regenerative energy circuit

[0111] 404 Driver circuit

[0112] 405 Rechargeable power source

[0113] 406 Rechargeable power source

[0114] 407 Motor

[0115] X First direction

[0116] Y Second direction

[0117] Z Third direction