JP4070580B2 - Transport cart - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transport cart for transporting cargo such as containers, and more particularly to an unmanned transport cart that travels unattended.
[0002]
[Prior art]
In general, in the case of a transport cart that transports cargo such as containers, especially an unmanned transport cart, the axle to which the wheel of the unmanned transport cart is attached is used to realize accurate and safe transport during the transport of the unmanned transport cart. A structure that is supported by a vehicle body via a hydraulic cylinder is employed, and various structures have been proposed as this type of structure.
[0003]
As a conventional automatic guided vehicle, for example, as shown in FIG. 4, wheels W1 to W8 are attached to shaft axles 1 to 4, and each of the shaft axles 1 to 4 is supported on a vehicle body via a hydraulic cylinder. The cylinder is divided into four blocks, front and rear, left and right, and the hydraulic cylinders in each block are communicated by communication lines 6 to 9 and the hydraulic cylinders of one of the left and right blocks can be communicated by the communication line 10. There is a feature (see Patent Document 1).
[0004]
[Patent Document 1]
JP 2000-255242 A (page 1-4, FIG. 1)
[0005]
[Problems to be solved by the invention]
By the way, in the conventional automatic guided vehicle, it is difficult to accurately grasp the weight and center of gravity of the cargo to be transported, and the load contained in the cargo may change dynamically. When the transport cart turns, an unbalanced load acts on the cargo, and the traveling stability of the unmanned transport cart may not be sufficiently exhibited. Also, due to the unbalanced load, the load applied to the axle and wheels of the automated guided vehicle exceeds the allowable load in terms of structural strength or unmanned guidance control, and the functions of the axle and wheels of the automated guided vehicle are not fully exhibited. There is a fear.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an automatic guided vehicle in which running stability is sufficiently exhibited and functions of its axle and wheels are sufficiently exhibited.
[0007]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
The invention according to claim 1 is an unmanned transport cart including a vehicle body on which cargo is mounted, a wheel provided on the vehicle body, and a drive device that rotationally drives the wheel. The first detection means for detecting the load acting on the vehicle, the second detection means for detecting the load acting on the other of the vehicle body in the width direction, and the detection results of the first or second detection means. A control unit that controls the drive device, and the control unit detects when the load detected by the first or second detection means exceeds an allowable load on the structural strength of the wheel. The number of rotations of the wheel is reduced.
According to a second aspect of the present invention, there is provided a transport cart that includes a vehicle body on which a cargo is mounted, a wheel provided on the vehicle body, and a drive device that rotationally drives the wheel. The first detection means for detecting the load acting on the vehicle, the second detection means for detecting the load acting on the other of the vehicle body in the width direction, and the detection results of the first or second detection means. A control unit that controls the drive device, and the control unit detects the wheel when the load detected by the first or second detection unit exceeds an allowable load on unmanned guidance. The number of rotations is reduced.
[0008]
According to this invention, since the control unit that controls the drive device is provided based on the detection result of the first or second detection unit, the control unit causes the transport carriage to travel from the result of the detection unit. Will be controlled.
[0010]
When the load detected by the first or second detection means exceeds the existing upper limit value, by reducing the number of rotations of the wheels, the transport carriage travels in a range not exceeding the existing upper limit value; Become.
[0011]
The invention according to claim 2 is characterized in that the control unit reduces the number of rotations of the wheel when the load detected by the first or second detection means falls below an existing lower limit value. To do.
[0012]
According to this invention, when the load detected by the first or second detection means falls below the existing lower limit value, the conveyance carriage does not exceed the existing lower limit value by decreasing the rotation speed of the wheel. It will run in the range.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 are diagrams showing an embodiment of the present invention, and are schematic views showing a transport carriage to which the present invention is applied.
The transport carriage (AGV) 10 includes a wheel 11, an axle 12, a vehicle body 13, a hydraulic cylinder 14 as a buffering unit, a driving device 15, a control unit 16, a pressure sensor 17 as a detecting unit, and an accumulator 18 as a vibration suppressing unit. It is prepared for.
[0014]
A plurality of wheels 11 are arranged below the AGV 10 so as to be able to travel on the traveling surface.
The axle 12 is provided at the lower part of the AGV 10 with a pair of wheels 11 disposed at both ends thereof.
The vehicle body 13 has wheels 11 installed on one side and the other side in the width direction via an axle 12, and is disposed on the upper side of the wheels 11 and the axle 12, and can carry cargo such as containers and the like. It is installed as follows.
[0015]
The hydraulic cylinder 14 is provided so as to be interposed between the axle 12 and the vehicle body 13 and is disposed so as to be able to absorb the load received from the traveling surface.
The driving device 15 is usually provided at the lower portion of the vehicle body 13 and is disposed so that the wheels 11 can be rotationally driven via the axle 12.
The control unit 16 is connected to the drive device 15 and arranged so that the drive device 15 can be controlled.
[0016]
The pressure sensor 17 is a pressure sensor 17a serving as a first detection unit that detects a load acting on one side in the width direction of the vehicle body 13, and a second detection unit that detects a load acting on the other side in the width direction of the vehicle body 13. As a pressure sensor 17b.
The accumulator 18 is provided in the hydraulic cylinder 14 so as to contain a fluid therein and to suppress vibration of the vehicle body 13.
[0017]
Next, the operation of the AGV 10 having the above configuration will be described.
When the AGV 10 travels along a curve, if an eccentric load is generated on the cargo mounted on the vehicle body 13 of the AGV 10 due to a centrifugal force generated on the AGV 10, the AGV 10 is equipped with the AGV 10 to suppress the uneven load. The controller 16 thus operated operates to control the AGV 10 driving device 15 to decelerate the AGV 10.
[0018]
That is, for example, when the AGV 10 travels a curve that turns to the left with respect to the traveling direction, centrifugal force is generated in the right direction with respect to the traveling direction of the AGV 10, and the cargo mounted on the vehicle body 13 of the AGV 10 is Since the load contained in the cargo moves the center of gravity in the right direction with respect to the traveling direction, the center of gravity moves in the right direction, so that the AGV 10 is inclined in the right direction with respect to the traveling direction. At this time, the wheel 11 and the axle 12 provided on the right side with respect to the traveling direction of the AGV 10 are loaded with the eccentric load generated by the inclination of the AGV 10 and the wheel provided on the left side with respect to the traveling direction. 11, the reaction force received from the running surface due to the inclination of the AGV 10 becomes extremely small. Here, when the reaction force becomes 0, that is, the wheel 11 and the traveling surface may be separated from each other.
[0019]
FIG. 3 is a flowchart showing how the AGV 10 controls traveling.
When the drive device 15 of AGV10 starts traveling start, preset cylinder area A, the threshold _{K 1} and _{K 2} (step S1). Cylinder area A is the cross-sectional area of the hydraulic cylinder 14 provided on the AGV 10, the threshold _{K 1} is distanced and the running surface and the wheel 11 of the AGV 10, determining whether there is a risk that AGV 10 has overturning The value to be The threshold value K2 is a value for determining whether the load applied to the undercarriage of the wheel 11 and the axle 12 of the AGV ₁₀ is an allowable load in terms of structural strength or unmanned guidance control.
The threshold values K ₁ and K ₂ are, for example, a value that is 20% of W with respect to the load W applied to the hydraulic cylinder 14 in a stationary state before starting running and when the predetermined value is set in advance. May be preset as K ₁ and a numerical value of 120% of W as K ₂ .
The allowable load is an allowable load in terms of structural strength or unmanned guidance control.
[0020]
The pressure applied to the wheel 11 and the axle 12 from the traveling surface is detected by a pressure signal via the hydraulic cylinder 14 by the pressure sensor 17 provided in the AGV 10 (step S2). The pressure signal is separately calculated as a pressure value P (step S3), and a suspension load W that is the product of the pressure value P and the cylinder area A measured in advance is calculated (step S4).
[0021]
Comparing the suspension load W and the threshold value _{K 1,} when the suspension load W is greater than the threshold value _{K 1} (step S5), and while the wheels 11 and the axle 12 receives the threshold value _{K 1} is greater than a predetermined load Since the AGV 10 is traveling, that is, the AGV 10 is traveling with the wheels 11 not being separated from the traveling surface, it is determined that traveling stability is ensured. Furthermore, by comparing the suspension load W and the threshold _{K 2,} when the suspension load W is the threshold _{K 2} is smaller than (step S6), and while the wheels 11 and the axle 12 is subjected to a load of less than the allowable load AGV10 Therefore, it is determined that there is no problem in traveling with respect to the AGV 10. Therefore, the AGV 10 travels at a constant speed without controlling the driving device 15 by the control unit 16 (step S7).
[0022]
However, by comparing the suspension load W and the threshold value _{K 1,} when the suspension load W is the threshold _{K 1} is smaller than (step S5), and while the wheels 11 and the axle 12 receives the threshold value _{K 1} is smaller than the load It is determined that the AGV 10 is traveling, that is, the wheels 11 are separated from the traveling surface and the AGV 10 may fall over. Therefore, the control unit 16 provided in the AGV 10 is operated to control the driving device 15 that drives the AGV 10 to reduce the rotational speed of the wheel 11 to reduce the traveling speed of the AGV 10 (step S8). The process returns to step S2.
[0023]
Furthermore, by comparing the suspension load W and the threshold _{K 2,} when the suspension load W is greater than the threshold value _{K 2} (step S6), and the wheels 11 and the axle 12 is AGV10 while receiving a load exceeding the allowable load Since the vehicle is traveling, it is determined that the traveling speed needs to be reduced with respect to the AGV 10. Therefore, the control unit 16 operates to control the driving device 15 to reduce the rotational speed of the wheel 11, thereby reducing the traveling speed of the AGV 10 (step S8) and returning to step S2.
Thereafter, the AGV 10 continues to travel until it reaches the instructed target position (step S9). When the AGV 10 reaches the target position, the travel of the AGV 10 ends.
[0024]
According to the above configuration, when there is a risk of the AGV 10 falling over, or when a load greater than the allowable load is applied to the wheel 11, that is, when a factor for controlling the traveling of the AGV 10 occurs, the control provided in the AGV 10 The driving device 15 of the AGV 10 is controlled by the part 16 and the traveling speed of the AGV 10 is reduced by reducing the number of rotations of the wheels 11, so that it is possible to suppress the uneven load on the AGV 10 and to thereby stabilize the traveling of the AGV 10. The load applied to the wheel 11 and the axle 12 of the AGV 10 can be suppressed to an allowable load or less.
[0025]
In addition, since a detection means should just be able to detect gravity, it may install not only the pressure sensor 17 but a load cell, for example.
Further, in the conventional technique, the hydraulic cylinder is divided into four blocks, front, rear, left and right, and the hydraulic cylinders in each block are configured to communicate with each other. The same as above.
[0026]
Further, by providing an accumulator 18 as a vibration suppressing means in the hydraulic cylinder 14, when an unbalanced load is generated on the AGV 10, the accumulator 18 acts to suppress the unbalanced load by suppressing the vibration of the vehicle body 13 of the AGV 10. The load applied to the wheel 11 and the axle 12 can be reduced.
[0027]
In addition, the AGV 10 applied to the present invention is not limited to a yard that handles cargo such as containers, but is a place where an unmanned system for transporting loads can be constructed, such as a steel mill, shipyard, paper mill, etc. If so, application of this AGV10 is possible.
[0028]
【The invention's effect】
The transport carriage of the present invention described above has the following effects.
According to the first aspect of the present invention, since the control unit that controls the drive device is provided based on the detection result of the first or second detection unit, the control unit can convey the result from the detection unit. Since the traveling of the carriage is controlled, the running stability of the transport carriage is ensured and the functions of the axle and wheels can be sufficiently exhibited.
[0029]
When the load detected by the first or second detection means exceeds the existing upper limit value, by reducing the number of rotations of the wheels, the transport carriage travels in a range not exceeding the existing upper limit value; Therefore, the running stability of the transport carriage is ensured, and the functions of the axle and wheels can be sufficiently exhibited.
[0030]
According to the second aspect of the present invention, when the load detected by the first or second detection means falls below the existing lower limit value, the conveyance carriage is set to the existing lower limit by decreasing the rotational speed of the wheel. Since it will drive | work in the range which does not exceed a value, while the traveling stability of the conveyance trolley | bogie is ensured, the function of the axle shaft and a wheel can fully be exhibited.
[Brief description of the drawings]
FIG. 1 is a schematic view of a transport carriage according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view of a transport carriage according to an embodiment of the present invention.
FIG. 3 is a flowchart showing a traveling control method for a transport carriage according to an embodiment of the present invention.
FIG. 4 is a schematic view showing a transport cart according to a conventional technique.
[Explanation of symbols]
10 AGV (conveying cart)
16 Control part 17 Pressure sensor (detection means)
18 Accumulator (vibration suppression means)

Claims (3)

In a transport cart that travels unattended comprising a vehicle body carrying cargo, wheels provided on the vehicle body, and a drive device that rotationally drives the wheels,
A first detecting means for detecting a load acting on one of the width directions of the vehicle body; a second detecting means for detecting a load acting on the other of the width direction of the vehicle body; and the first or second A control unit for controlling the drive device based on the detection result of the detection means,
The control unit reduces the rotation speed of the wheel when the load detected by the first or second detection unit exceeds an allowable load on the structural strength of the wheel. Trolley. In a transport cart that travels unattended comprising a vehicle body carrying cargo, wheels provided on the vehicle body, and a drive device that rotationally drives the wheels,
A first detecting means for detecting a load acting on one of the width directions of the vehicle body; a second detecting means for detecting a load acting on the other of the width direction of the vehicle body; and the first or second A control unit for controlling the drive device based on the detection result of the detection means,
The transport cart, wherein the control unit reduces the number of rotations of the wheel when the load detected by the first or second detection unit exceeds an allowable load on unmanned guidance . In the conveyance trolley | bogie of Claim 1 or 2 ,
The transport cart, wherein the control unit reduces the number of rotations of the wheel when the load detected by the first or second detection means falls below an existing lower limit value.

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