JP6446884B2 - Transport system for automated guided vehicles - Google Patents

Description

  The present invention relates to a transport system for an automatic guided vehicle.

  The conveyance system of an automatic guided vehicle makes an automatic guided vehicle travel on a predetermined traveling path. On the other hand, in a hybrid vehicle, securing a large amount of regenerative power is an important factor that leads to improved fuel efficiency. Normally, a hybrid vehicle controls the battery charge rate (SOC) so that it is approximately in the middle of the operating range (for example, 50%). However, when trying to collect a large amount of regenerative power, if the SOC before deceleration is at the center of the control value, the usable SOC range is small. Patent Document 1 has a battery and a capacitor in a hybrid system of an electric vehicle, and restricts charging of the battery at the time of regenerative braking to increase the share of charging to the capacitor.

JP-A-5-30608

  By the way, in a large automatic guided vehicle traveling with containers loaded, the vehicle weight (including the load) is about 20 tons when not loaded, and is about 60 tons when loaded with containers. Sometimes it is about 3 times different. This is a very different point from automobiles. Since the amount of regenerative electric power during deceleration varies depending on the vehicle weight, the fluctuation range of the battery charge rate (SOC) changes greatly. Then, the square value of the amount of current that determines the life of the battery becomes large, which becomes a factor of shortening the life. Further, when the regenerative amount is large and the battery charge rate is used up to an upper limit (for example, 80%), an area that promotes battery deterioration is used due to the progress of an irreversible reaction or the like. On the other hand, when the technology disclosed in Patent Document 1 is used so that a capacitor can be connected in parallel to the battery, and when the regenerative current is large, the capacitor is recovered. Will be switched. If this is done, there will be a delay between the detection of the large current and the completion of the switching operation, and this delay will cause a large current to flow through the battery, adversely affecting the battery life.

  The objective of this invention is providing the conveyance system of the automatic guided vehicle which can aim at the lifetime improvement of the battery mounted in the automatic guided vehicle.

  According to the first aspect of the present invention, in the transport system for an automatic guided vehicle that travels a predetermined traveling path, the automatic guided vehicle equipped with a traveling motor and a battery for driving the traveling motor is provided. A capacitor or a resistor that is mounted on the vehicle and is arranged so as to be able to branch a regenerative current that is generated when braking by the traveling motor; a switch that is mounted on the automatic guided vehicle and that branches the regenerative current to the capacitor or the resistor; Before regeneration of the automatic guided vehicle, calculation means for calculating at least one of a maximum current during regeneration and a charging rate of the battery during regeneration, and a maximum current during regeneration and a value during regeneration calculated by the calculation means It is determined whether or not at least one of the charging rates of the battery is greater than a threshold value, and if it is greater, the regenerative current is divided into the capacitor or resistor before regeneration. And switch changeover means for switching said switch beforehand in order to be summarized as further comprising a.

  According to the first aspect of the present invention, the regenerative current generated when the capacitor or the resistor is braked by the traveling motor is arranged to be able to branch, and the regenerative current can be branched to the capacitor or the resistor by the switch. In the calculating means, before the regeneration of the automatic guided vehicle, at least one of the maximum current during regeneration and the charging rate of the battery during regeneration is calculated. Then, in the switch switching means, it is determined whether or not at least one of the calculated maximum current during regeneration and the charging rate of the battery during regeneration is larger than a threshold value, and if so, the regeneration current is branched to a capacitor or a resistor before regeneration. The switch is switched accordingly. As a result, when a large regenerative current is about to flow, the switch is switched in advance, so that the regenerative current is branched into a capacitor or a resistor, and the life of the battery mounted on the automatic guided vehicle can be extended.

  According to a second aspect of the present invention, in the conveyance system for the automatic guided vehicle according to the first aspect, when the maximum current at the time of regeneration calculated by the calculation unit is larger than a threshold value, the branching to the capacitor or the resistor is performed. The timing for switching the switch to be terminated may be different from the timing for switching the switch to terminate branching to the capacitor or resistor when the charging rate of the battery during regeneration is greater than a threshold value.

  In the transport system of the automatic guided vehicle according to claim 2, the maximum current at the time of regeneration calculated by the calculation unit is larger than a threshold value and the battery is charged at the time of regeneration. When the rate is greater than the threshold, the switch may be switched to end the branch to the capacitor or resistor at the timing when the charge rate of the battery during regeneration is greater than the threshold.

According to a fourth aspect of the present invention, in the conveyance system for the automatic guided vehicle according to any one of the first to third aspects, the capacitor may be connected to a drive source that consumes electric charges.
As described in claim 5, in the transport system of the automatic guided vehicle according to claim 4, it is preferable that the capacitor is discharged in advance before current is passed through the capacitor during regeneration.

  ADVANTAGE OF THE INVENTION According to this invention, the lifetime improvement of the battery mounted in the automatic guided vehicle can be achieved.

The schematic plan view of the container terminal in which the conveyance system of the automatic guided vehicle of embodiment is used. The figure which shows the structure of an automatic guided vehicle. The flowchart for demonstrating an effect | action of the conveyance system of an automatic guided vehicle. (A) is time-series data regarding vehicle speed, (b) is time-series data regarding current, (c) is time-series data regarding charging rate, and (d) and (e) are for explaining the operation of the switch. FIG. (A), (b), (c) is an electrical block diagram for operation | movement description of the conveyance system of an automatic guided vehicle. Time chart for vehicle speed and current. Time chart for vehicle speed and current. (A), (b) is an electrical block diagram for operation | movement description of the conveyance system of another example of an automatic guided vehicle.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
In this embodiment, the conveyance system of the automatic guided vehicle is applied when performing the operation management of the automatic guided vehicle at the container terminal of the port.

  FIG. 1 shows a schematic plan view of a container terminal in a harbor. In the container terminal, the automatic guided vehicle 30 travels on a circuit course (counterclockwise circuit course indicated by a white arrow in FIG. 1). The automated guided vehicle 30 has a hybrid system for driving. Containers are loaded and unloaded by the gantry crane 50 from the container ship S1. The container loaded and unloaded by the gantry crane 50 is mounted on the automatic guided vehicle 30.

  Travel paths 40 and 41 for automatic guided vehicles are set in the container terminal. The automatic guided vehicle 30 travels on the traveling paths 40 and 41 with containers. The automatic guided vehicle 30 travels through the travel path 40 to the rubber tire crane 60 as a destination. The container is unloaded from the automatic guided vehicle 30 by the rubber tire crane 60. The automatic guided vehicle 30 that is unloaded with the container unloaded travels through the traveling path 41 and returns to the gantry crane 50. When the automatic guided vehicle 30 is run, the straight line speeds up, but the curve passes at a medium speed.

Next, the configuration of the automatic guided vehicle 30 will be described with reference to FIG.
The vehicle body 31 of the automatic guided vehicle has four wheels 32. The vehicle body 31 includes a travel motor 33, a speed reducer 34, an inverter 36, a battery (power storage device) 35, an in-vehicle computer (ECU) 37, a charge rate detection unit (battery ECU) 38, wireless communication, in addition to the travel engine En. A device 39 and the like are mounted. A series hybrid system is configured by the engine En and the traveling motor 33. The engine En may be a diesel engine or a gasoline engine. The electric power of the battery 35 is supplied to the traveling motor 33 via the inverter 36, and the two wheels 32a are rotationally driven via the speed reducer 34 by the driving of the traveling motor 33 accompanying this power supply. Further, when the automatic guided vehicle 30 is decelerated, electric power is generated by regeneration from the traveling motor 33 and the inverter 36, and the generated electric power is charged in the battery 35. Examples of the battery 35 include a nickel metal hydride secondary battery, a lithium ion secondary battery, and a lead storage battery. Thus, the automatic guided vehicle 30 is equipped with the traveling motor 33 and the battery 35 for driving the traveling motor 33.

The charge rate detection unit 38 detects the charge rate (SOC) of the battery 35. The detection result of the charging rate (SOC) of the battery 35 by the charging rate detection unit 38 is sent to the in-vehicle computer 37.
The automatic guided vehicle 30 is equipped with a capacitor 80, a switch 81, a fan motor 82, and a switch 83. A capacitor 80 and a switch 81 are connected in series, and both ends of this series circuit are connected to the positive and negative terminals of the battery 35. A fan motor 82 and a switch 83 are connected in series, and both ends of the series circuit are connected to both terminals of the capacitor 80. The capacitor 80 is provided so that the regenerative current generated when braking by the traveling motor 33 can be branched. The switch 81 is for branching the regenerative current to the capacitor 80.

  The in-vehicle computer 37 controls the inverter 36, switches (relay switches) 81, 83, and the like. When the switch 81 is closed, the regenerative current from the inverter 36 is branched and supplied to the capacitor 80. That is, normally, the switch 81 is open and the regenerative current from the inverter 36 is supplied to the battery 35, but the regenerative current from the inverter 36 is also supplied to the capacitor 80 by closing the switch 81. On the other hand, the electric charge stored in the capacitor 80 is used for driving the fan motor 82 by closing the switch 83, and the cooling fan 84 rotates as the fan motor 82 is driven, so that the cooling air is cooled (engine En, traveling). Motor 33, battery 35, etc.). The wireless communication device 39 communicates with an external control tower 70 (see FIG. 1).

  As shown in FIG. 1, a control tower 70 is provided as a configuration of the transport system 10 of the automatic guided vehicle. The control tower 70 has a data server. Then, the control tower 70 receives, from the data server, information on the load weight when the automatic guided vehicle 30 travels on the predetermined traveling paths 40 and 41 (load information when the next automatic guided vehicle travels), and The position information of the automatic guided vehicle 30 (the positional information when the next automatic guided vehicle travels) is acquired.

  The control tower 70 performs wireless communication with the wireless communication device 39 of the automatic guided vehicle 30, and a traveling command is sent from the control tower 70 to the in-vehicle computer 37 via the wireless communication device 39 of the automatic guided vehicle 30. In accordance with this travel command, the in-vehicle computer 37 of the automatic guided vehicle 30 causes the automatic guided vehicle 30 to travel on predetermined travel paths 40 and 41 while controlling speed, acceleration, and the like.

  Further, the control tower 70 sends a command to the gantry crane 50 to perform a desired operation (loading work). The control tower 70 sends a command to the rubber tire crane 60 to perform a desired operation (loading work).

  The in-vehicle computer 37 of the automated guided vehicle 30 calculates the current during regeneration of the next automated guided vehicle 30 and calculates the charging rate (SOC) of the battery 35 when the automated guided vehicle 30 travels. To do.

Next, the operation of the transport system 10 for the automatic guided vehicle will be described.
FIG. 3 is a flowchart for explaining the operation, and FIGS. 4A, 4B, and 4C are time series data on the vehicle speed, the regenerative current, and the battery charge rate (SOC) for explaining the operation. FIG. 4D and FIG. 4E are explanatory diagrams for explaining the operation of the switch 81. FIG. 5 is an operation explanatory diagram on the capacitor 80 side.

  In FIG. 4A, it is assumed that the vehicle speed increases at the timing of t1, shifts to constant speed travel at the timing of t2, starts deceleration at the timing of t3, and shifts to constant speed travel at the timing of t4. . That is, regeneration is performed during the period from t3 to t4, before the timing of t3 is before regeneration, and after the timing of t4 is after regeneration.

At normal times, as shown in FIG. 5A, the current from the inverter 36 is supplied to the battery 35, and the battery 35 is charged.
When the capacitor 80 is used, as shown in FIG. 5B, the switch 83 is closed and the fan motor 82 is driven by the electric charge stored in the capacitor 80 to be used by the cooling fan 84.

  During large current regeneration, as shown in FIG. 5C, the switch 81 is closed and the charging current is also sent to the capacitor 80 side. That is, at the time of large current regeneration in the early stage of deceleration, the regenerative current is also branched to the capacitor 80 side to reduce the load on the battery 35.

  Before deceleration, that is, before regeneration, the in-vehicle computer 37 calculates the maximum current during regeneration and the charging rate of the battery 35 during regeneration, and calculates the calculated maximum current during regeneration and the charging rate of the battery 35 during regeneration. It is determined whether at least one is larger than the threshold value, and if it is larger, the switch 81 is switched in advance to branch the regenerative current to the capacitor 80 before regeneration.

  A regenerative current is generated during deceleration during the period from t3 to t4 in FIG. As a comparative example, when the regenerative current is sent only to the battery, the allowable value is exceeded. In other words, if the current exceeds a permissible value, the load on the battery increases due to the sum of squares of the current, causing a reduction in battery life. In contrast, in the present embodiment, the battery 35 and the capacitor 80 are charged with a regenerative current. As a result, when the regenerative current is sent only to the battery as a comparative example, the allowable value is exceeded, but it is avoided that the allowable value is exceeded by branching. Therefore, the current load applied to the battery can be reduced and the life can be extended.

  Regarding the charging rate (SOC) of the battery, the comparative example uses the vicinity of the upper limit of the SOC, which becomes a factor of shortening the battery life. In the present embodiment, by branching, as shown in FIG. 4C, the areas A2 and A3 that should not be used for the lifetime are removed, and the area A1 that can be actively used is set as the control area. be able to. As a result, it is possible to reduce the SOC fluctuation of the battery, prevent deterioration, and extend the life.

  As system operation, after obtaining the load weight and running pattern, estimate the amount of regenerative power during deceleration in advance, and branch the battery (lead storage battery, etc.) considering the amount of regenerative current and the battery charge rate (SOC) Take control.

  Here, when the amount of regenerative current is large, the current sum of squares (I ^ 2), which is an indicator of battery life, increases. Therefore, in addition to the battery 35 serving as a base, it branches to the capacitor 80 to reduce the sum of current squares. Extend battery life.

  In addition, when regeneration is performed near the upper limit of the charging rate (SOC) of the battery 35, an area that promotes deterioration of the battery life is used. Therefore, in addition to the battery 35 serving as a base, the battery 80 is branched to Reduces the use of the 35 charge rate (SOC) upper limit and extends battery life.

  Further, the timing indicated by t10 in FIG. 4 (e) is a timing for switching the switch 81 to end the branching to the capacitor 80 when the maximum current during regeneration is larger than the threshold value, and t10 is the battery current when not branching. Is the timing when the value falls below the allowable value. Also, the timing indicated by t11 in FIG. 4D is the timing for switching the switch 81 to end the branching to the capacitor 80 when the charging rate of the battery at the time of regeneration is greater than the threshold, and regeneration ends at t11. Timing (= t4). Here, the timing t10 (FIG. 4E) for turning off the switch 81 is different from the timing t11 (FIG. 4D). In particular, when the calculated maximum current during regeneration is greater than a threshold and the battery charging rate during regeneration is greater than the threshold, the switch is performed at a timing (= t11) when the battery charging rate during regeneration is greater than the threshold. 81 is switched to end the branch to the capacitor 80.

  Further, as described with reference to FIG. 5B, since the capacitor 80 is connected to the fan motor 82 as a drive source that consumes charges, the capacitor 80 is preliminarily applied before the current flows through the capacitor 80 during regeneration. Can be discharged and consumed.

A specific branch control logic will be described.
Branch control during regeneration is performed according to the following procedure. In FIG. 3, steps 100 to 106 are processes performed before regeneration, step 107 is an operation performed during regeneration, and steps 108 and 109 are processes performed after regeneration.

  As shown in FIG. 3, at the timing before the start of regeneration, the in-vehicle computer 37 receives load information after several steps from the control tower 70, which is the host system, at step 100.

  In step 101, the in-vehicle computer 37 receives position information after several steps from the control tower 70. That is, information indicating where the automatic guided vehicle 30 is traveling is received after how many seconds.

In step 102, the in-vehicle computer 37 calculates the current In after several steps (during regeneration). That is, the regenerative current is obtained from the vehicle speed at the travel position of the automatic guided vehicle 30.
In step 103, the in-vehicle computer 37 calculates the battery charge rate SOCn after several steps (during regeneration).

  In step 104, the in-vehicle computer 37 proceeds to the next logic when the current In during regeneration is larger than a predetermined allowable current amount Iadj or when the battery charge rate SOCn during regeneration is larger than a predetermined allowable value SOCadj.

  In step 105, the in-vehicle computer 37 actively uses the capacitor 80. That is, as shown in FIG. 5B, power is consumed before a large regenerative current to flow through the capacitor 80 during regeneration.

In step 106, the in-vehicle computer 37 turns on the branch switch 81 (see FIG. 5C).
In step 107, the regenerative current is branched (divided) into the battery 35 and the capacitor 80.

If the regeneration is completed, the in-vehicle computer 37 turns off the branching switch 81 in step 108 (see FIG. 5A).
The in-vehicle computer 37 uses the capacitor 80 in a timely manner as shown in FIG.

Next, as a comparative example, the case where the switch is switched by detecting the regenerative current and the case where the switch is switched by prediction in advance as in this embodiment will be described.
In the method in which the generation of current is detected by a sensor and the computer closes the switch, a large current flows to the battery. In this embodiment, the in-vehicle computer 37 predicts and determines a large current in advance, issues a switch switching command, and switches the switch 81. Therefore, when a large current is generated, it is regenerated in the capacitor 80.

  In this way, when branching to the capacitor 80 at the time of regeneration from the viewpoint of the life (deterioration) of the battery 35, a configuration in which the amount of regenerative electric power at the time of deceleration is estimated in advance, switching when using the capacitor 80, etc. The occurrence of a response delay on the control surface is avoided.

A case where a large regenerative current (peak current) is generated at the initial stage of rapid deceleration will be described with reference to FIGS.
FIG. 6 shows a case where a regenerative current is detected and a switch (relay switch) is switched at a timing t20 as a comparative example, and FIG. 7 shows an embodiment in which the switch (relay switch) is switched in advance at a timing t21. is there.

  When a large current flows, a large current is generated at the initial timing as shown in FIGS. 6 and 7, and if the switch is switched at the timing of t20 in FIG. 6, the battery is damaged by the large current generated during sudden deceleration. Adversely affects lifespan.

  Here, a case is considered in which a capacitor can be connected in parallel to the battery, and when the regenerative current is large, the capacitor is recovered. At this time, if the switch is switched after detecting a large current, a delay occurs between the detection of the large current and the completion of the switching operation. Due to this delay, a large current flows through the battery. Specifically, when a current sensor or the like is attached when determining a large current, it always takes time to complete switching. More specifically, large current generation → current sensor reaction → notification to control device → control device judgment → switch switching command → switch switching operation → regenerative operation by capacitor, large current to battery due to time lag from detection of large current Will flow. In FIG. 6, the battery bears the large current during the large current generation period T1 in the early stage of sudden deceleration, and the capacitor (and the battery) bears the current during the subsequent period T2.

  On the other hand, in this embodiment, the capacitor 80 (and the battery 35) bears the large current including the large current over the entire period T3 during the rapid deceleration by switching the switch before the large current is generated at the timing of t21 in FIG. Therefore, the switch switching at the initial timing has a great meaning and can greatly contribute to the extension of the battery life.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the transport system 10 of the automatic guided vehicle, a capacitor 80, a switch 81, and an in-vehicle computer 37 are provided. The in-vehicle computer 37 as the calculating means calculates the maximum current during regeneration and the charging rate of the battery 35 during regeneration before regeneration of the automatic guided vehicle. The in-vehicle computer 37 serving as the switch switching means determines whether or not at least one of the calculated maximum current during regeneration and the charging rate of the battery during regeneration is greater than a threshold, and if so, the regeneration current is supplied to the capacitor 80 before regeneration. The switch 81 is switched in advance to branch. Therefore, when a large regenerative current is about to flow, the switch 81 is switched in advance, so that the regenerative current is branched to the capacitor 80, eliminating the factor that shortens the life of the battery 35 mounted on the automatic guided vehicle, and has a long life Can be achieved.

  That is, the current load on the battery 35 can be suppressed, and the life of the battery 35 can be extended. Further, by controlling the SOC fluctuation range of the battery 35 and not using the SOC region that should not be used, it is possible to extend the battery life.

  (2) When the calculated maximum current during regeneration is greater than the threshold, the timing of switching the switch 81 to end the branching to the capacitor 80, and when the charge rate of the battery 35 during regeneration is greater than the threshold, to the capacitor 80 Since the timing of switching the switch 81 is different in order to end the branching, it is preferable in practice.

  (3) When the calculated maximum current during regeneration is greater than the threshold and the battery charging rate during regeneration is greater than the threshold, the switch 81 is connected to the capacitor at a timing when the battery charging rate during regeneration is greater than the threshold. Since it switches so that the branch to 80 may be complete | finished, it is preferable practically.

(4) Since the fan motor 82 as a drive source for consuming electric charge is connected to the capacitor 80, it is practically preferable.
(5) Discharge the capacitor 80 before passing a current through the capacitor 80 during regeneration. Therefore, it is preferable for charging with the capacitor 80.

The embodiment is not limited to the above, and may be embodied as follows, for example.
A resistor may be used instead of the capacitor 80. For example, a resistor R1 is used as shown in FIG. Specifically, a series circuit is configured by the battery 35 and the switch SW1, and a series circuit is configured by the resistor R1 and the switch SW2, and these series circuits are connected in parallel. In this way, a branch circuit is formed by using the regenerative resistor R1, and the battery load during regeneration is reduced.

  In FIG. 8A, the switch SW1 is closed at normal times, and a regenerative current is supplied to the battery 35. In FIG. 8B, at the time of large current regeneration, that is, at the time of large current regeneration at the initial stage of deceleration, the switch SW2 is closed to reduce the load of the battery 35 by waste heat at the resistor R1.

Therefore, the current load on the battery can be suppressed, the battery life can be extended, the SOC fluctuation range of the battery can be controlled, and the battery life can be extended.
-The hybrid system for automated guided vehicles may be a parallel system, a series system, or a series parallel system.

  In addition to the hybrid automatic guided vehicle having the traveling engine En and the traveling motor 33 mounted thereon, the present invention may be applied to an electric automated guided vehicle having no engine and having the traveling motor 33 mounted thereon.

  ・ Switch switching is based on one of the maximum current during regeneration (large current at the time of regeneration) and the charging rate of the battery at the time of regeneration. You may form the path | route which flows. In short, before regeneration of the automated guided vehicle, calculate at least one of the maximum current during regeneration and the battery charge rate during regeneration, and at least the calculated maximum current during regeneration and the battery charge rate during regeneration. If one of them is larger than the threshold value and it is larger, the switch may be switched in advance to branch the regenerative current to the capacitor or the resistor before regeneration.

  DESCRIPTION OF SYMBOLS 10 ... Transfer system of automatic guided vehicle, 30 ... Automatic guided vehicle, 33 ... Traveling motor, 35 ... Battery, 37 ... In-vehicle computer, 38 ... Charge rate detection part, 40 ... Traveling path, 41 ... Traveling path, 80 ... Capacitor, 81 ... switch, 82 ... fan motor, R1 ... resistor, SW2 ... switch.

Claims (5)

In a transport system for an automated guided vehicle that travels a predetermined traveling path, a traveling motor and an automated guided vehicle equipped with a battery for driving the traveling motor,
A capacitor or a resistor mounted on the automatic guided vehicle and arranged to be able to branch a regenerative current generated when braking by the traveling motor;
A switch mounted on the automated guided vehicle for branching a regenerative current to the capacitor or resistor;
Obtaining load position information and position information of the automatic guided vehicle traveling on the traveling path, and calculating at least one of a maximum current during regeneration and a charging rate of the battery during regeneration before regeneration,
It is determined whether or not at least one of the maximum current during regeneration and the charging rate of the battery during regeneration calculated by the calculating means is greater than a threshold value, and if so, the regeneration current is branched to the capacitor or resistor before regeneration. And a switch switching means for switching the switch in advance.
  When switching the switch to finish branching to the capacitor or resistor when the maximum current during regeneration calculated by the calculation means is greater than a threshold, and when the charging rate of the battery during regeneration is greater than the threshold 2. The transport system for an automatic guided vehicle according to claim 1, wherein a timing at which the switch is switched to finish branching to the capacitor or the resistor is different.   When the maximum current at the time of regeneration calculated by the calculating means is larger than a threshold value and the charging rate of the battery at the time of regeneration is larger than the threshold value, the timing at which the charging rate of the battery at the time of regeneration is larger than the threshold value. 3. The transport system for an automatic guided vehicle according to claim 2, wherein the switch is switched to end the branch to the capacitor or the resistor.   The conveyance system of the automatic guided vehicle according to any one of claims 1 to 3, wherein the capacitor is connected to a drive source that consumes electric charges.   5. The transport system for an automatic guided vehicle according to claim 4, wherein the capacitor is discharged in advance before current flows through the capacitor during regeneration.