Electric transport vehicle

Abstract

An electric transport vehicle travels by the driving force of an electric motor driven by power supplied from a generator driven by an engine. A controller for controlling an electric motor is provided with: an engine rotation speed determination unit for determining whether or not an engine rotation speed, which is a detection value of a rotation speed sensor, is equal to or greater than a rotation speed threshold value when a vehicle departure instruction is input; an elapsed time determination unit that determines whether or not a first elapsed time from a point in time at which the detection value is determined to be equal to or greater than the rotational speed threshold value has reached a time threshold value; and a departure determination unit that, after determining that the first elapsed time has reached the time threshold value, determines whether or not the vehicle speed, which is the detection value of the speed sensor, is equal to or greater than the speed threshold value, and when determining that the detection value of the speed sensor is less than the speed threshold value, the controller stops the electric motor.

Description

Technical Field

[0001] The present invention relates to a transport vehicle such as a dump truck for transporting ore and earth and sand excavated in a mine or the like, and more particularly to an electric transport vehicle that travels by the driving force of an electric motor driven by electric power supplied from a generator mechanically connected to an engine. Background Art

[0002] In open-pit mining, transport vehicles such as dump trucks transport excavated ore and soil. The transport vehicle usually loads the transported objects into the cargo box at the loading site where the minerals are excavated, drives on the transport road with the transported objects loaded, and discharges the transported objects at the dump site (dumping the soil). The transport vehicle that has discharged the transported objects and emptied the cargo box drives on the transport road again and returns to the loading site, and loads the transported objects into the cargo box again. The transport vehicle performs such loading and dumping operations repeatedly.

[0003] There are the following methods for a transport vehicle to release the transported object in the soil dumping site. The first method is that the transport vehicle moves backwards toward the target position while changing its position little by little in a wide flat area, and directly releases the soil onto the ground. The second method is that the transport vehicle moves backwards to the entrance of a hopper or just in front of a cliff, and releases the soil into the hopper or the cliff.

[0004] When the second method is used, there is an advantage that the soil can be discharged from a roughly determined location every time. However, there is a concern that the transport vehicle may fall into the hopper or under the cliff due to excessive travel when retreating to the soil discharge position. Therefore, in order to prevent the vehicle from falling, a car blocker composed of a soil pile is provided in front of the hopper or the cliff. Even if the transport vehicle is about to overdrive from the soil discharge position, its travel can be suppressed by the travel resistance of the car blocker.

[0005] In recent years, the above-mentioned transport vehicles have been electrified for the purpose of reducing maintenance costs due to the reduction of mechanical parts such as transmissions. A common type of electric transport vehicle is one that generates electricity through a generator mechanically connected to an engine, and supplies the generated electricity of the generator to an electric motor installed on the rear wheel (drive wheel), thereby using the electric motor as a driving source for travel.

[0006] In an electric transport vehicle with an electric motor as a driving source, if the output of the electric motor continues even if it is in a state of being unable to travel due to contact with a car blocker, the energy of the electric motor (driving source) is wasted, or the load on the drive mechanism is increased, resulting in a reduction in energy efficiency. In addition, for autonomous transport vehicles that have been introduced in recent years in mines and other places, if the state of being unable to travel continues due to contact with a car blocker even if a departure command is output, there is a concern that the departure command is not completed and the vehicle will fall into a deadlock where it cannot move forward to the next command. Based on these reasons, it is hoped that the electric transport vehicle can determine whether it is in a state of being unable to travel due to contact with a car blocker, and stop the driving source of the vehicle when it is determined to be in a state of being unable to travel.

[0007] As a technology for determining whether a vehicle wheel is in contact with a blocker and is in a state where the vehicle cannot travel, the technology described in Patent Document 1 is proposed. The driving support device described in Patent Document 1 calculates the degree of deviation between the acceleration in the front-rear direction of the vehicle estimated based on the braking force and driving force (the combined force of the braking force and the driving force) generated by the driving operation detected by the braking force and driving force detection unit and the acceleration in the front-rear direction of the vehicle detected by the acceleration detection unit, and determines whether the vehicle is in contact with the blocker based on the calculated degree of deviation. The driving support device is assumed to be mounted on a mass-produced vehicle such as an automobile.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2012-116360 Summary of the invention

[0011] When the technology described in Patent Document 1 is used to determine whether a vehicle is in contact with a brake when the vehicle starts, in order to estimate the acceleration of the vehicle with high accuracy, it is necessary to successively detect the braking force and the driving force generated by the driving operation with high accuracy. In the case of an electric vehicle, the driving force of the braking force and the driving force generated by the driving operation is calculated based on the value of the output torque of the electric motor, so it is necessary to detect the output torque of the electric motor with high accuracy.

[0012] However, in large electric transport vehicles used in mines, large electric motors are required as driving sources, so permanent magnet synchronous motors, which are used in ordinary passenger electric vehicles, are not used, but induction motors are usually used. This is because induction motors can be made larger than permanent magnet motors by using winding excitation, and can also cope with harsh environments such as vibration, shock, and high temperature.

[0013] Due to the principle of generating rotational force, it is difficult to detect the output torque of the motor of the induction motor with high accuracy when the vehicle starts. The induction motor generates torque (rotational force) by the interaction between the rotating magnetic field generated by exciting the stator winding on the housing side and the induced current generated by the rotor winding on the output shaft side. The induced current is generated by the difference (sliding) between the rotation speed of the rotating magnetic field and the rotation speed of the rotor. The induction motor can calculate the output torque of the motor by using the motor speed detected by the sensor. However, when the vehicle starts, the rotor of the induction motor is almost stationary and the rotation speed is extremely small, so it is very difficult to measure the rotation speed of the induction motor (rotor) with high accuracy using a sensor.

[0014] Thus, when an induction motor is used as a driving source for the vehicle, it is difficult to detect the output torque of the motor with high accuracy. Therefore, if the technology described in Patent Document 1 is used to determine whether the vehicle is in contact with the vehicle blocker when the vehicle starts, it is difficult to correctly estimate the acceleration of the vehicle, resulting in failure to make a normal judgment.

[0015] The present invention is made to solve the above-mentioned problems, and its purpose is to provide an electric transport vehicle that can reliably determine whether the vehicle is unable to start due to contact with a vehicle blocker when the vehicle starts, even when an induction motor is used as the vehicle's driving source.

[0016] The present application includes a plurality of methods for solving the above-mentioned problems. As an example, an electric transport vehicle is provided, comprising: an engine; a generator mechanically driven by the engine; an electric motor driven by electric power supplied from the generator; a rotation speed sensor for detecting the rotation speed of the engine; a speed sensor for detecting the vehicle speed; and a controller for controlling the driving of the electric motor, wherein the electric transport vehicle travels by the driving force of the electric motor, thereby transporting goods, and wherein the controller comprises: an engine rotation speed determination unit, which determines whether the detection value of the rotation speed sensor is greater than a rotation speed threshold when a vehicle departure instruction is input; an elapsed time determination unit, which measures a first elapsed time from a time point when the engine rotation speed determination unit determines that the detection value of the rotation speed sensor is greater than the rotation speed threshold, and determines whether the first elapsed time has reached a time threshold; and a departure determination unit, which determines whether the detection value of the speed sensor is greater than a speed threshold after the elapsed time determination unit determines that the first elapsed time has reached the time threshold, and when the departure determination unit determines that the detection value of the speed sensor is less than the speed threshold, the controller stops the electric motor.

[0017] Effects of the Invention

[0018] According to the present invention, after the first elapsed time from the time point when the engine speed reaches the speed threshold reaches the time threshold, it is determined whether the vehicle speed reaches the speed threshold, thereby taking into account the acceleration time from the start of the vehicle's movement to the driving state detectable by the speed sensor, it is possible to determine whether the electric transport vehicle is in contact with the blocker and is in a state where it cannot be started, thereby preventing errors in the determination. That is, it is possible to reliably determine whether the vehicle is in a state where it cannot be started due to contact with the blocker when the vehicle is started.

[0019] Other problems, structures, and effects than those described above will become apparent from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is an external view showing a dump truck as an electric transport vehicle according to the first embodiment of the present invention.

[0021] Figure 2 This is a block diagram showing a schematic structure of an electric travel system in the electric transport vehicle according to the first embodiment and a controller that controls the electric travel system.

[0022] Figure 3 Yes means Figure 2 A flowchart showing an example of a control procedure of a controller of the electric transport vehicle according to the first embodiment shown.

[0023] Figure 4 This is a time chart showing an example of the time transition of the engine speed and the vehicle speed at the time of departure in the electric transport vehicle according to the first embodiment.

[0024] Figure 5 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a second embodiment of the present invention and a controller that controls the electric travel system.

[0025] Figure 6 Yes means Figure 5 1 is a flowchart showing an example of a control procedure of a controller of an electric transport vehicle according to the second embodiment shown.

[0026] Figure 7 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a modification of the second embodiment and a controller that controls the electric travel system.

[0027] Figure 8 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a third embodiment of the present invention and a controller that controls the electric travel system.

[0028] Fig. 9 Yes means Figure 8 1 is a flowchart showing an example of a control procedure of a controller of an electric transport vehicle according to a third embodiment shown in FIG.

[0029] Fig.10 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a first modified example of the third embodiment and a controller that controls the electric travel system.

[0030] Fig.11 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a second modification of the third embodiment and a controller that controls the electric travel system.

[0031] Fig.12 Yes means Fig.11 1 is a flowchart of an example of a control procedure of a controller of an electric transport vehicle according to a second modification of the third embodiment shown in FIG. DETAILED DESCRIPTION

[0032] Hereinafter, an embodiment of the electric transport vehicle of the present invention will be described using the drawings. In this embodiment, a dump truck is used as an example of an electric transport vehicle. In addition, the front, back, left, and right directions described in this specification represent directions viewed from an operator riding in the electric transport vehicle.

[0033] [First embodiment]

[0034] First, use Figure 1 A schematic structure of a dump truck as an electric transport vehicle according to a first embodiment of the present invention will be described. Figure 1 This is an external view showing a dump truck as an electric transport vehicle according to the first embodiment.

[0035] Figure 1 In the present invention, a dump truck 1 as an electric transport vehicle transports goods W such as ore and earth and sand mined in a mine and travels by the driving force of an electric motor 11 described later. The dump truck 1 has: a front-rear direction ( Figure 1 The vehicle body frame 2 is a supporting structure extending in the left and right directions; wheels, namely, front wheels 3 and rear wheels 4, are rotatably arranged on the left and right sides of the front and rear parts of the vehicle body frame 2; a cabin 5 is arranged at the front part of the vehicle body frame 2; and a cargo box 6 is mounted on the vehicle body frame 2 so as to be able to rise and fall (tilt). The front part of the vehicle body frame 2 is equipped with an engine 12, a generator 13, and an inverter 14 (see the following) for supplying power to the electric motor 11. Figure 2 )wait.

[0036] The front wheel 3 is, for example, a steering wheel steered by an operator. The rear wheel 4 is a driving wheel rotationally driven by an electric motor 11. A front suspension 7 is provided between the front part of the vehicle body frame 2 and the front wheel 3 to absorb vibrations received from the road surface and to mitigate impacts to the vehicle body frame 2 during travel. A rear suspension 8 is provided between the rear part of the vehicle body frame 2 and the rear wheel 4 to absorb vibrations received from the road surface and to mitigate impacts to the vehicle body frame 2 during travel. The front suspension 7 and the rear suspension 8 include, for example, a suspension cylinder in which compressible oil is sealed, and have a mechanism that uses the compression of oil by a piston as a spring.

[0037] The cabin 5 is a part for the operator to ride in and operate the vehicle. The cabin 5 is provided with a driver's seat (not shown) for the operator to sit on, an operating pedal 21 (see the following description) for driving the dump truck 1, and a control pedal 22 (not shown) for driving the dump truck 1. Figure 2 ), a steering wheel (not shown) for steering the front wheels 3, an operating unit (not shown) for operating the ups and downs of the cargo box 6, and other various operating devices used by the operator to operate the dump truck 1.

[0038] The cargo box 6 is a part for loading cargo W, and its rear end is rotatably mounted to the rear end of the vehicle body frame 2 via a rotation pin 2a. A lifting cylinder 9 is provided between the vehicle body frame 2 and the cargo box 6 to raise and lower the cargo box 6. The cargo box 6 is configured to tilt relative to the vehicle body frame 2 between a transport rotation position (solid line) where cargo W is loaded on the cargo box 6 and transported, and a soil release rotation position (double-dotted line) where cargo W is released from the cargo box 6, by extension and retraction of the lifting cylinder 9.

[0039] The dump truck 1 has a rotation speed sensor 23 (see below) for detecting the rotation speed of the engine 12. Figure 2 ), a vehicle speed sensor 24 for detecting vehicle speed (speed of the dump truck 1), an acceleration sensor for detecting vehicle acceleration (acceleration of the dump truck 1), and a load sensor 25 for detecting the load weight of the cargo W. The vehicle speed sensor 24 is, for example, a speed sensor for detecting the rotation speed of the rear wheel 4. The load sensor 25 is, for example, a pressure sensor for detecting the pressure in the suspension cylinders of the front suspension 7 and the rear suspension 8. In addition to the pressure sensor, the load sensor can also be configured to use a sensor that can detect the force acting on the front suspension 7 and the rear suspension 8. In addition, the load sensor can also be configured to use a weight sensor provided in the placement portion of the cargo box 6.

[0040] The dump truck 1 thus constructed is used to load soil and sand as cargo W (transported objects) into the cargo box 6 by a loading machine such as an excavator or a wheel loader at a loading site. The dump truck 1 loaded with the transported objects W in the cargo box 6 drives the rear wheels 4 to rotate by the driving force of the electric motor 11, thereby traveling along the transport road. In the dumping site, the operator extends the lifting cylinder 9, thereby moving the cargo box 6 from the transport rotation position ( Figure 1 The solid line in the figure) is tilted to the soil release rotation position ( Figure 1 The dump truck 1 that has discharged the transported objects W and emptied the cargo box 6 starts from the soil dumping site, travels along the transport road, and returns to the loading site again. The dump truck 1 repeatedly performs loading in the loading site, driving from the loading site to the soil dumping site or from the soil dumping site to the loading site, and soil dumping in the soil dumping site.

[0041] The dump truck 1, for example, moves backwards in the soil dumping area to a place just before a drop-in port called a hopper or a cliff (not shown) and stops, and dumps the transported object W in the cargo box 6 into the hopper or the cliff. In this case, in order to prevent the dump truck 1 from overrunning beyond the travel stop position when moving backwards, a car blocker 100 made of a soil pile or the like is provided in front of the hopper or the cliff in the soil dumping area. When the dump truck 1 is about to overrun beyond the travel stop position, the travel resistance of the car blocker 100 restricts the travel of the dump truck 1.

[0042] Next, use Figure 2 A general structure of an electric travel system in an electric transport vehicle according to a first embodiment and hardware and functions of a controller for controlling the electric travel system will be described. Figure 2 Yes means Figure 1 FIG. 1 is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a first embodiment and a controller for controlling the electric travel system.

[0043] The electric travel system of the dump truck 1 includes an electric motor 11 that rotates and drives the rear wheel 4 (wheel), a generator 13 that supplies power to the electric motor 11, an engine 12 that drives the generator 13, and an inverter 14 that adjusts the power supplied from the generator 13 to the electric motor 11. The electric motor 11 is composed of an induction motor. The generator 13 is mechanically connected to the engine 12 and generates electricity by being driven by the engine 12. The engine 12 is configured so that its rotation speed increases when the vehicle starts and when the acceleration operation is performed. The engine 12 has an engine control unit (not shown) that controls the engine speed according to an instruction from a controller 30 described later. The engine 12 is provided with the above-mentioned speed sensor 23 that detects the rotation speed of the engine 12. The engine 12 (engine control unit) outputs the detection value (engine speed Ne) of the speed sensor 23 to the controller 30 described later. The inverter 14 controls the torque and speed of the electric motor 11 according to an instruction from the controller 30 described later. In the case of an electric travel system, mechanical elements such as transmission gears constituting a mechanical travel drive system are not required, so it is possible to reduce maintenance costs such as management of lubricating oil and disassembly and inspection of equipment.

[0044] The controller 30 controls the electric travel system of the dump truck 1 based on the operation signal Pi input from the operation pedal 21 and the information (engine speed Ne, etc.) input from the engine 12 (engine control unit). The controller 30 is configured to control the driving of the engine 12 of the electric travel system via the engine control unit and to control the driving of the electric motor 11 of the electric travel system via the inverter 14. Figure 1 ) in the case of an autonomous driving type in which the truck 1 is driven by an operator's operation, the controller 30 is configured to control the electric driving system of the dump truck 1 according to an autonomous driving instruction Si from the control station 60.

[0045] Here, it is assumed that the dump truck 1 is in contact with the vehicle blocker 100 ( Figure 1 If the driving force of the electric motor 11 is continuously output even in the state of being unable to start, the power (energy) supplied to the electric motor 11 is wasted, and the energy efficiency is reduced. In addition, in the case where the dump truck 1 is an autonomous driving type, even if a departure instruction is output from the control station 60, if the state of being unable to start continues due to contact with the vehicle blocker 100, there is a concern that the vehicle will be locked in that the departure instruction is not completed and the next instruction cannot be advanced.

[0046] Therefore, the controller 30 of the dump truck 1 of the present embodiment is configured to determine whether the front wheel 3 or the rear wheel 4 (wheel) contacts the blocker 100 when the dump truck 1 is started, and to control the electric motor 11 to stop when it is determined that the dump truck 1 is in a state where it cannot start. Thus, waste of power (energy) supplied to the electric motor 11 is prevented. In addition, when the dump truck 1 is an autonomous driving type, deadlock with respect to the start instruction is prevented.

[0047] Specifically, the controller 30 is constituted as hardware, for example, having a storage device 31 composed of a RAM and a ROM, and a processing unit 32 composed of a CPU and an MPU, etc., including a timer capable of measuring time. In the storage device 31, programs and various information necessary for controlling the electric travel system when the dump truck 1 is started are stored in advance. The processing unit 32 reads the program and various information from the storage device 31 as appropriate, and performs processing according to the program, thereby realizing various functions including the following functions. The controller 30 has a driving torque command unit 41, an engine speed judgment unit 42, an elapsed time judgment unit 43, and a start judgment unit 44 as functions executed by the processing unit 32 when the dump truck 1 is started.

[0048] The driving torque command unit 41 receives an operation signal Pi corresponding to the operation amount of the operating pedal 21 or an autonomous driving instruction Si (acceleration instruction, deceleration instruction, etc.) from the control station 60, and calculates the command value of the driving torque applied by the electric motor (induction motor) 11 to the wheel (rear wheel 4) based on the received operation signal Pi or autonomous driving instruction Si. Basically, the command value Ci of the supply current to the electric motor (induction motor) 11 corresponding to the command value of the driving torque as the calculation result is output to the inverter 14. Thus, the controller 30 controls the driving of the electric motor (induction motor) 11 (the driving of the vehicle) via the inverter 14. However, when the judgment result of the inability to start the vehicle described later is input from the departure judgment unit 44, the command of the supply current value calculated based on the operation signal Pi of the operating pedal 21 or the autonomous driving instruction Si from the control station 60 is not output, but a command of the supply current value "0" as a command to stop the electric motor 11 is output. The stop command for the electric motor 11 may be a command to gradually reduce the supply current value (drive torque) to "0" finally.

[0049] The induction motor 11 can output forward or backward torque according to the rotation direction (forward or reverse) of the rotating magnetic field. In addition, the induction motor 11 can output torque for accelerating the vehicle or torque for decelerating the vehicle by regenerative braking according to the magnitude relationship between the rotation speed of the rotating magnetic field and the rotation speed of the wheel (rear wheel 4). In addition, the operating pedal 21 is composed of two pedals, for example, an accelerator pedal for accelerating operation and a decelerator pedal for decelerating operation, and the direction of the output torque of the induction motor 11 can be switched by operating the accelerator pedal or the decelerator pedal.

[0050] For this purpose, the driving torque command unit 41 assigns a positive or negative sign to the driving torque command value as the calculation result according to the direction of application of the output torque of the induction motor 11, thereby being able to express command values ​​corresponding to all forward and backward movements and acceleration and deceleration of the vehicle. For example, as the sign of the driving torque command value, acceleration during forward movement is set to positive and braking is set to negative, and conversely, braking during reverse movement is set to positive and acceleration is set to negative. In the case where the vehicle is moving backward on a path to a soil dumping position, etc., if the amount of operation of the accelerator pedal constituting the operating pedal 21 increases, the driving torque command unit 41 increases the driving torque command value in the negative direction. On the other hand, if the amount of operation of the deceleration pedal constituting the operating pedal 21 increases, the driving torque command value is increased in the positive direction.

[0051] When the start of the vehicle start operation is input, the engine speed determination unit 42 monitors the engine speed and determines whether the engine speed is greater than the speed threshold value Nth. Specifically, the engine speed Ne, which is the detection value of the speed sensor 23 output from the engine control unit of the engine 12, is received, and the engine speed Ne is determined to be greater than the speed threshold value Nth. The speed threshold value Nth is an indicator for determining whether the generator 13 can supply the electric motor 11 with sufficient power required for the start of the dump truck 1.

[0052] In the case of a large electric transport vehicle such as one for use in mines, the engine 12 is also large, so it takes some time for the engine speed to rise when the vehicle is started. Moreover, the torque of the engine 12 is not only used to increase the speed of the engine 12 itself, but also used to drive the generator 13. Therefore, depending on the start load of the electric transport vehicle, it may take a longer time to increase the engine speed. Therefore, as an indicator for judging whether the generator 13 is in a state where it can supply enough power required for the vehicle to start, the elapsed time from the start of the start operation cannot be used.

[0053] Therefore, the controller 30 uses the engine speed Ne as an indicator of the power generated by the generator 13. The power generated by the generator 13 driven by the engine 12 increases as the speed of the engine 12 increases, so when the engine speed Ne is greater than the speed threshold Nth, it can be considered that the generator 13 is in a state where it can generate enough power required for the start of the dump truck 1. The speed threshold Nth is stored in advance in the storage device 31, for example.

[0054] When the engine speed determination unit 42 determines that the engine speed Ne, which is the detection value of the speed sensor 23, is greater than the speed threshold value Nth, the elapsed time determination unit 43 measures the elapsed time Ta from the time point of the determination by the engine speed determination unit 42, and determines whether the measured elapsed time Ta has reached the time threshold value Tth. The time threshold value Tth is an indicator for determining whether the time for the dump truck 1 to start moving and accelerate to enter the driving state has elapsed. The time threshold value Tth is stored in advance in the storage device 31, for example.

[0055] The departure judgment unit 44 judges whether the dump truck 1 has departed when the elapsed time judgment unit 43 judges that the measured elapsed time Ta has reached the time threshold Tth. Specifically, when the elapsed time judgment unit 43 judges that the elapsed time Ta has reached the time threshold Tth, the departure judgment unit 44 receives the detection value of the vehicle speed sensor 24, that is, the vehicle speed Vs, and judges whether the vehicle speed Vs is greater than the speed threshold Vth. When it is judged that the vehicle speed Vs is lower than the speed threshold Vth, it is considered that the front wheel 3 or the rear wheel 4 of the dump truck 1 is in contact with the stopper 100 when the dump truck 1 departs, and the determination result Df of the inability to depart is output to the drive torque command unit 41.

[0056] The speed threshold Vth is set to a speed that the vehicle speed sensor 24 can reliably detect, and a speed that can reliably confirm that the dump truck 1 is in a running state without contacting the blocker 100. When the dump truck 1 is in a state where the front wheel 3 or the rear wheel 4 contacts the blocker 100 and cannot start, the vehicle speed Vs does not reach the speed threshold Vth. On the other hand, when the front wheel 3 or the rear wheel 4 does not contact the blocker 100 at the time of departure, after the time threshold Tth has passed from the state where the dump truck 1 can start, the vehicle speed Vs rises and reaches the speed threshold Vth. Therefore, it can be judged whether the dump truck 1 is started according to whether the vehicle speed Vs reaches the speed threshold Vth. The speed threshold Vth can be set to a fixed value pre-stored in the storage device 31. In addition, the speed threshold Vth can also be set to change according to the operation amount of the departure operation of the operating pedal 21 or the target speed of the departure instruction from the control station 60.

[0057] Next, use Figure 3 A vehicle start control procedure of the controller of the electric transport vehicle according to the first embodiment will be described. Figure 3 Yes means Figure 2 FIG. 1 is a flowchart showing an example of a vehicle start control procedure of a controller of an electric transport vehicle according to the first embodiment shown.

[0058] Figure 3 middle, Figure 2 The controller 30 shown in the figure determines whether or not a departure instruction of the dump truck 1 is input (step S10). If it is determined that a departure instruction of the dump truck 1 is input, the process proceeds to step S20. On the other hand, if it is determined otherwise, the control process ends. For example, when the detection value Vs of the vehicle speed sensor 24 is 0, and an operation signal indicating an acceleration instruction of the operation pedal 21 (operation signal of the accelerator pedal) or an acceleration instruction from the control station 60 is input, it is determined that a departure instruction of the dump truck 1 is input. In other cases, it is determined that no departure instruction is input.

[0059] When it is determined to be yes (input of departure instruction) in step S10, the driving torque instruction unit 41 of the controller 30 outputs the driving torque instruction value for the electric motor 11 calculated based on the operating pedal 21 or the acceleration instruction from the control station 60 to the inverter 14 (step S20). In detail, the driving torque instruction value for the electric motor 11 is calculated based on the operating pedal 21 or the acceleration instruction from the control station 60, and the driving torque instruction value as the calculation result is output to the inverter 14 as the current value supplied from the generator 13 to the electric motor 11, that is, the supply current instruction value Ci. As a result, the inverter 14 supplies the electric power generated by the generator 13 driven by the engine 12 to the electric motor 11 according to the supply current instruction value (driving torque instruction value). In addition, the output of the driving torque instruction value to the inverter 14 by the controller 30 continues during the execution of the steps after step S20.

[0060] Next, the controller 30 determines whether the engine speed Ne detected by the speed sensor 23 is greater than the speed threshold Nth (step S30). Specifically, the engine speed determination unit 42 determines by comparing the engine speed Ne detected by the speed sensor 23 with the speed threshold Nth pre-stored in the storage device 31. When the engine speed Ne is lower than the speed threshold Nth (no), the controller 30 returns to step S30 again, and the determination of the above step S30 is repeated until the engine speed Ne becomes greater than the speed threshold Nth (yes).

[0061] In the case of YES in step S30, the controller 30 starts measuring the elapsed time Ta from the time point when the engine speed determination unit 42 determines that the engine speed Ne is above the speed threshold Nth (YES), and determines whether the measured elapsed time Ta exceeds the time threshold Tth (step S40). Specifically, the elapsed time determination unit 43 determines by comparing the measured elapsed time Ta with the time threshold Tth pre-stored in the storage device 31. In the case that the elapsed time Ta does not exceed the time threshold Tth (NO), the controller returns to step S40 again, and the determination of step S40 is repeated until the elapsed time Ta exceeds the time threshold Tth (becomes YES).

[0062] In the case of yes in step S40, the controller 30 determines whether the vehicle speed Vs detected by the vehicle speed sensor 24 is greater than the speed threshold Vth (step S50). Specifically, the departure determination unit 44 makes a determination by comparing the vehicle speed Vs detected by the vehicle speed sensor 24 with the speed threshold Vth pre-stored in the storage device 31. In the case where the vehicle speed Vs is higher than the speed threshold Vth (in the case of yes), it is determined that the departure is completed and the control flow ends. On the other hand, in the case where the vehicle speed Vs is lower than the speed threshold Vth (in the case of no), the process proceeds to step S60.

[0063] In the case of No in step S50, that is, when the vehicle speed Vs is lower than the speed threshold value Vth, the drive torque command unit 41 outputs a stop command to the inverter 14 to stop the electric motor 11 (step S60). In detail, the departure determination unit 44 outputs the determination result Df of "No" in step S50, which is the determination result that the vehicle cannot depart, to the drive torque command unit 41. The drive torque command unit 41 changes the drive torque command value from the calculated value corresponding to the acceleration instruction of the operating pedal 21 or the control station 60 in step S20 to "0" as a stop command according to the input of the determination result Df of "No" that the vehicle cannot depart.

[0064] This series of processing is as follows: when a vehicle departure instruction is input, first, it is determined whether the generator 13 has reached a state where it can supply enough power for the electric motor 11 to output a driving force for the vehicle to depart, and then it is determined whether the vehicle has accelerated since the vehicle started to move and reached a driving state at a speed detectable by the vehicle speed sensor 24. Through these determinations, it is possible to reliably determine whether the dump truck 1 has departed without contacting the blocker 100 or cannot depart due to contacting the blocker 100, without detecting the driving torque of the induction motor 11.

[0065] Next, use Figures 2 to 4 The operation of the electric transport vehicle according to the first embodiment will be described. Figure 4 This is a time chart showing an example of the time transition of the engine speed and the vehicle speed at the time of departure in the electric transport vehicle according to the first embodiment.

[0066] Figure 4 In the figure, the upper figure shows the time transition of the departure instruction of the operating pedal 21, that is, the operation amount of the accelerator pedal. The middle figure shows the time transition of the engine speed Ne relative to the departure instruction of the operating pedal 21 shown in the upper figure. The lower figure shows the time transition of the vehicle speed Vs relative to the departure instruction of the operating pedal 21 shown in the upper figure.

[0067] like Figure 4As shown in the figure above, the case where the departure instruction of the operating pedal 21 is input at time T1 is described. With respect to the departure instruction of the operating pedal 21, Figure 2 The controller 30 shown in FIG. 1 increases the engine speed Ne from the idle speed Ni to the target speed corresponding to the operation amount of the operating pedal 21 via the engine control unit of the engine 12. However, the torque of the engine 12 is not only used to increase the speed of the engine 12 itself, but also used to drive the generator 13. Therefore, it takes some time to increase the engine speed Ne from the idle speed Ni to the target speed. Figure 4 As shown in the middle diagram of , the engine speed Ne gradually increases from the idle speed Ni at time T1 and finally reaches the target speed.

[0068] When a start instruction is inputted by operating the pedal 21 at time T1, the controller 30 of the present embodiment determines whether the engine speed Ne is equal to or higher than the speed threshold value Nth ( Figure 3 In the short period of time from time T1, as shown in step S30. Figure 4 As shown in the middle figure of , the engine speed Ne has not reached the speed threshold value Nth.

[0069] If the engine speed Ne reaches the speed threshold Nth at time T2, the controller 30 determines that the engine speed Ne is above the speed threshold Nth, and measures the elapsed time Ta ( Figure 3 If the measured elapsed time Ta exceeds the time threshold Tth, that is, if the elapsed time Ta reaches Figure 4 The controller 30 determines that the vehicle speed Vs (V T3 ) exceeds the speed threshold Vth( Figure 3 Step S50 shown).

[0070] When the departure instruction is input at time T1, the controller 30 outputs the drive torque instruction of the electric motor 11 calculated based on the operation amount of the operation pedal 21 to the inverter 14 ( Figure 3 As a result, the electric power generated by the generator 13 driven by the engine 12 is supplied to the electric motor 11 via the inverter 14. The electric motor 11 intends to rotate and drive the rear wheel 4 by the driving torque. However, during a short period of time from time T1, if Figure 4 As shown in the middle figure of FIG, the engine speed Ne is not high, so the power generated by the generator 13 is not enough to drive the rear wheel 4. Figure 4As shown in the figure below, the travel speed (vehicle speed Vs) of the dump truck 1 is kept stationary (speed 0) for a short period from time T1. Then, the engine speed Ne gradually increases in accordance with the time from time T1, and reaches a level at which the power generated by the generator 13 can rotate and drive the rear wheels 4, thereby starting the dump truck 1 to move.

[0071] At this time, when the front wheels 3 or the rear wheels 4 of the dump truck 1 are not in contact with the blocker 100, the dump truck 1 that starts to move is accelerated by the driving torque of the electric motor 11, so the vehicle speed Vs gradually increases. Figure 4 In the figure below, when the vehicle speed Vs reaches V at time T3 T3 In this case, the controller 30 determines that the vehicle speed Vs (V T3 ) is above the speed threshold Vth ( Figure 3 (Yes in step S50 shown in the figure) In this case, the output of the drive torque command to the inverter 14 in accordance with the operation amount of the operation pedal 21 continues.

[0072] On the other hand, when the front wheels 3 or the rear wheels 4 of the dump truck 1 come into contact with the blocker 100, the dump truck 1 is unable to start due to the blocker 100. Therefore, even if time has passed since time T1, the vehicle speed Vs of the dump truck 1 is still at or near "0" which means that the dump truck 1 is unable to start. That is, at time T3, the vehicle speed Vs is at or near "0". In this case, the controller 30 determines that the vehicle speed Vs (Vs) at time T3 is T3 ) is lower than the speed threshold Vth( Figure 3 In this case, the controller 30 outputs a command to set the drive torque to “0” to the inverter 14 regardless of the operation amount of the operation pedal 21 as a stop command of the electric motor 11 .

[0073] In this way, in the present embodiment, the controller 30 determines whether the vehicle speed Vs is above the speed threshold value Vth when the time Ta from the time point when the engine speed Ne is determined to be above the speed threshold value Nth has passed the time threshold value Tth. The time threshold value Tth is a threshold value that takes into account the acceleration time from the beginning of the movement of the dump truck 1 to the state of being in motion. When the dump truck 1 is in a state where the front wheel 3 or the rear wheel 4 contacts the blocker 100 and is unable to start, the vehicle speed Vs will not exceed the speed threshold value Vth. On the other hand, when the dump truck 1 has started without contacting the blocker 100, the dump truck 1 is in a state of motion where the vehicle speed Vs exceeds the speed threshold value Vth after the time threshold value Tth has passed. Therefore, the controller 30 can judge whether the dump truck 1 is in a state where it is unable to start by contacting the blocker 100 without detecting the driving torque of the electric motor 11 through the above judgment.

[0074] Moreover, in the present embodiment, the controller 30 is configured to stop the electric motor 11 when it is determined that the vehicle speed Vs does not exceed the speed threshold Vth when the elapsed time Ta exceeds the time threshold Tth. Thus, when the vehicle contacts the blocker 100 and is in a state where the vehicle cannot start, the output of the electric motor 11 is prevented from continuing, thereby suppressing the energy waste of the electric motor 11. In addition, when the vehicle contacts the blocker 100 and is in a state where the vehicle cannot start during autonomous driving, it is possible to prevent the vehicle from being deadlocked and unable to move forward to the next instruction due to the incomplete start instruction.

[0075] As described above, the dump truck 1 (electric transport vehicle) of the first embodiment includes: an engine 12; a generator 13 mechanically driven by the engine 12; an electric motor 11 driven by electricity supplied from the generator 13; a speed sensor 23 for detecting the speed Ne of the engine 12; a vehicle speed sensor 24 (speed sensor) for detecting the vehicle speed Vs; and a controller 30 for controlling the drive of the electric motor 11. The dump truck 1 travels by the driving force of the electric motor 11, thereby transporting the cargo W. The controller 30 is constructed to include: an engine speed judgment unit 42, which judges whether the detection value Ne of the speed sensor 23 is above the speed threshold value Nth when a vehicle departure instruction is input; an elapsed time judgment unit 43 which measures the elapsed time Ta (first elapsed time) from the time point when the engine speed judgment unit 42 judges that the detection value Ne of the speed sensor 23 is above the speed threshold value Nth, and judges whether the elapsed time Ta (first elapsed time) has reached the time threshold value Tth; and a departure judgment unit 44, which judges whether the detection value Vs of the vehicle speed sensor 24 (speed sensor) is above the speed threshold value Vth after the elapsed time judgment unit 43 judges that the elapsed time Ta (first elapsed time) has reached the time threshold value Tth, and stops the electric motor 11 when the departure judgment unit 44 judges that the detection value Vs of the vehicle speed sensor 24 (speed sensor) is less than the speed threshold value Vth.

[0076] According to this configuration, after the time Ta (first elapsed time) from the time point when the engine speed Ne reaches the speed threshold Nth reaches the time threshold Tth, it is determined whether the vehicle speed Vs reaches the speed threshold Vth, thereby taking into account the acceleration time from the start of the tipper truck 1 (electric transport vehicle) at the time of departure to the travel state detectable by the vehicle speed sensor 24 (speed sensor), it is possible to determine whether the tipper truck 1 (electric transport vehicle) is in contact with the blocker 100 and is in a state where it cannot be started, thereby preventing errors in this determination. That is, it is possible to reliably determine whether the tipper truck 1 (electric transport vehicle) is in a state where it cannot be started due to contact with the blocker 100 when the vehicle is started.

[0077] [Second embodiment]

[0078] Next, use Figure 5 as well as Figure 6 An electric transport vehicle according to a second embodiment of the present invention will be described. Figure 5 as well as Figure 6 In the Figures 1 to 4 The parts with the same reference numerals as shown are the same parts, and thus their detailed description is omitted. Figure 5This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a second embodiment and a controller that controls the electric travel system.

[0079] Figure 5 The electric transport vehicle of the second embodiment shown is different from the first embodiment in the following points. The controller 30 of the first embodiment is configured such that the engine speed determination unit 42 uses the speed threshold Nth, which is a predetermined value, for determination. In contrast, the controller 30A of the second embodiment is configured such that the engine speed determination unit 42A changes the setting of the speed threshold Nth as a determination index according to the loading weight of the cargo W of the dump truck 1.

[0080] The gross weight of the dump truck 1 changes greatly depending on the presence or absence of the cargo W. As the gross weight of the dump truck 1 increases, the power generated by the generator 13 required for the start of the dump truck 1 also increases. The speed threshold Nth, which is a judgment index of the engine speed judgment unit 42A, is used as an index of whether the power generated by the generator 13 has reached the power required for the start of the dump truck 1. Therefore, it is preferred that the speed threshold Nth is not a fixed value, but changes according to the change in the gross weight of the dump truck 1 (the loading weight of the cargo W).

[0081] Specifically, the engine speed determination unit 42A receives the detection value of the pressure sensor 25 that functions as a load sensor for detecting the load weight of the cargo W, that is, the cylinder pressure Ps of the suspension 7, 8, and calculates the total weight of the dump truck 1 including the weight of the cargo W based on the detection pressure Ps of the pressure sensor 25. The power (energy) required for the start of the dump truck 1 is calculated based on the calculated total weight of the dump truck 1, and the speed threshold Nth is set according to the size of the power (energy) as the calculation result. That is, the engine speed determination unit 42A sets the speed threshold Nth in a manner that increases as the load weight of the cargo W increases. In addition, in the controller 30A of the present embodiment, the functional units of the drive torque command unit 41, the elapsed time determination unit 43, and the start determination unit 44 other than the engine speed determination unit 42A are the same as those in the first embodiment.

[0082] Next, use Figure 6 A vehicle start control procedure of the controller of the electric transport vehicle according to the second embodiment will be described. Figure 6 Yes means Figure 5 1 is a flowchart showing an example of a control procedure of a controller of an electric transport vehicle according to a second embodiment when the vehicle is started.

[0083] Figure 6 The control sequence of the controller 30A of the second embodiment shown in FIG. 1 is different from the control sequence of the controller 30 of the first embodiment (see FIG. 1 ). Figure 3 ) is different in the following points. When the departure instruction of the dump truck 1 is input, after step S20 in which the drive torque instruction corresponding to the operating pedal 21 or the acceleration instruction of the control station 60 is output to the inverter 14, the engine speed judgment unit 42A sets the speed threshold Nth according to the loading weight of the cargo W (step S25). Thus, the speed threshold Nth is set to increase as the loading weight of the cargo W increases. Moreover, the engine speed judgment unit 42A judges whether the detection value of the speed sensor 23, that is, the engine speed Ne, exceeds the speed threshold Nth set by step S25 (step S30A). In this case, because the speed threshold Nth is set to increase as the loading weight of the cargo W increases, it is possible to correctly judge whether the power generated by the generator 13 has reached the power required for the departure of the dump truck 1 through the engine speed Ne. In addition, the processing after step S30A (steps S40 to S60) is the same as that of the first embodiment.

[0084] According to the second embodiment described above, similarly to the first embodiment described above, after the time Ta (first elapsed time) from the time point when the engine speed Ne reaches the speed threshold Nth reaches the time threshold Tth, it is determined whether the vehicle speed Vs reaches the speed threshold Vth, thereby taking into account the acceleration time from the start of the movement of the dump truck 1 (electric transport vehicle) at the time of departure to the travel state detectable by the vehicle speed sensor 24 (speed sensor), it is possible to determine whether the dump truck 1 (electric transport vehicle) is in contact with the blocker 100 and is in a state where it cannot be started, thereby preventing errors in the determination. That is, it is possible to reliably determine whether the dump truck 1 (electric transport vehicle) is in a state where it cannot be started due to contact with the blocker 100 when the vehicle is started.

[0085] The dump truck 1 (electric transport vehicle) of this embodiment further includes a pressure sensor 25 as a load sensor for detecting the load weight of the cargo W. The rotation speed threshold Nth is set to be higher as the detection value of the pressure sensor 25 as the load sensor increases.

[0086] According to this configuration, the rotation speed threshold value Nth is not a fixed value but is set according to the loading weight of the cargo W. Therefore, the rotation speed threshold value Nth is an appropriate value considering the influence of the loading weight of the cargo W as an indicator for judging whether the power generated by the generator 13 has reached the power required for the start of the dump truck 1. Therefore, it is possible to reliably judge whether there is a state in which the dump truck 1 (electric transport vehicle) cannot start due to contact with the vehicle blocker 100 when the vehicle starts.

[0087] [Variation of the Second Embodiment]

[0088] Next, use Figure 7 An electric transport vehicle according to a modified example of the second embodiment of the present invention will be described. Figure 7 1 is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a modification of the second embodiment and a controller for controlling the electric travel system. Figure 7 In the middle, mark and Figures 1 to 6 The parts with the same reference numerals as shown are the same parts, and thus their detailed description is omitted.

[0089] Figure 7 The electric transport vehicle of the modified example of the second embodiment shown in the figure is different from the second embodiment in the following points. The engine speed determination unit 42A of the controller 30A of the second embodiment is configured to set the speed threshold value Nth according to the load weight (detection value of the pressure sensor 25) of the cargo W of the dump truck 1. In contrast, the engine speed determination unit 42B of the controller 30B of the modified example of the second embodiment is configured to set the speed threshold value Nth according to the tilt state (road slope) at the starting position of the dump truck 1.

[0090] When the road slope at the vehicle departure position of the dump truck 1 becomes an uphill slope relative to the traveling direction, it is considered that the power generated by the generator 13 required for the departure of the dump truck 1 will also increase in accordance with the uphill movement of the dump truck 1. The speed threshold Nth, which is a judgment index of the engine speed judgment unit 42B, is used as an index of whether the power generated by the generator 13 has reached the power required for the departure of the dump truck 1. Therefore, it is preferable that the speed threshold Nth is not a fixed value, but is set according to the magnitude of the road slope at the departure position.

[0091] In electric transport vehicles, a control function to prevent wheel slip is becoming common. In order to realize this control function, most electric transport vehicles are equipped with an acceleration sensor. The dump truck 1 of this embodiment also has an acceleration sensor 26.

[0092] The acceleration sensor 26 detects acceleration including gravitational acceleration in a coordinate system fixed to the vehicle (dump truck 1), for example, and detects the direction of gravity acting on the vehicle when the vehicle is stationary, thereby being able to detect the inclination of the vehicle relative to the horizontal plane. That is, the acceleration sensor 26 functions as an inclination sensor capable of detecting the road surface gradient at the starting position of the dump truck 1 by detecting the inclination of the vehicle relative to the horizontal plane. The inclination sensor may be composed of a sensor other than the acceleration sensor 26 as long as it is capable of detecting the road surface gradient at the starting position of the dump truck 1.

[0093] The engine speed determination unit 42B of the controller 30B of the present embodiment receives the inclination (road slope) of the dump truck 1 relative to the horizontal plane as the detection value As of the acceleration sensor 26, and sets the speed threshold value Nth according to the magnitude of the detection value As (road slope) of the acceleration sensor 26. That is, the engine speed determination unit 42B is set so that, when the traveling direction of the dump truck 1 indicated by the vehicle departure instruction is an uphill direction, the speed threshold value Nth becomes higher as the detection value As of the acceleration sensor 26, i.e., the road slope, becomes larger. Therefore, with respect to the road slope condition at the time of departure of the dump truck 1, it is possible to accurately determine whether the power required for the departure of the dump truck 1 is reached by the engine speed Ne.

[0094] In the controller 30B of the present embodiment, the functional units of the drive torque command unit 41, the elapsed time determination unit 43, and the vehicle start determination unit 44 other than the engine speed determination unit 42B are the same as those of the second embodiment. In addition, the control sequence of the controller 30B of the modified example of the second embodiment is different from that of the controller 30A of the second embodiment. Figure 6 The control procedure shown is the same except that in step S25 the engine speed determination unit 42B sets the speed threshold value Nth according to the road surface gradient at the starting position of the dump truck 1 .

[0095] According to the modification of the second embodiment described above, similarly to the second embodiment described above, it is possible to reliably determine whether the dump truck 1 (electric transport vehicle) is unable to start due to contact with the vehicle stopper 100 when the vehicle starts.

[0096] In addition, the dump truck 1 (electric transport vehicle) of the present embodiment further includes an acceleration sensor 26 as a tilt sensor capable of detecting a road slope. In addition, the above-mentioned speed threshold Nth is set to become higher as the detection value As of the acceleration sensor 26 as a tilt sensor becomes larger when the vehicle travel direction indicated by the vehicle departure instruction is an uphill direction.

[0097] According to this configuration, the rotation speed threshold Nth is not a fixed value, but is set according to the uphill road gradient, so the rotation speed threshold Nth is an appropriate value considering the influence of the uphill road gradient as an indicator for judging whether the power generated by the generator 13 has reached the power required for the start of the dump truck 1. Therefore, it is possible to reliably judge whether there is a state where the vehicle cannot start due to contact with the vehicle blocker 100 when the vehicle starts.

[0098] [Third Embodiment]

[0099] Next, use Figure 8 as well as Fig. 9The electric transport vehicle according to the third embodiment of the present invention will be described. Figure 8 as well as Fig. 9 In the Figures 1 to 7 The parts with the same reference numerals as shown are the same parts, and thus their detailed description is omitted. Figure 8 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a third embodiment and a controller that controls the electric travel system.

[0100] Figure 8 The electric transport vehicle of the third embodiment shown in the figure is different from the first embodiment as follows. In the controller 30 of the first embodiment, the elapsed time determination unit 43 uses a predetermined value, i.e., a time threshold Tth, to make a determination. In contrast, in the controller 30C of the third embodiment, the elapsed time determination unit 43C changes the setting of the time threshold Tth as a determination index according to the loading weight of the cargo W of the dump truck 1.

[0101] The gross weight of the dump truck 1 varies greatly depending on the presence or absence of cargo W. If the gross weight of the dump truck 1 is different, the time it takes for the vehicle speed Vs of the dump truck 1 to reach the speed threshold Vth will also change, even if the electric motor 11 applies the same drive torque to the rear wheels 4. It is known that when the drive torque of the electric motor 11 is fixed, that is, when the acceleration of the vehicle is fixed, the time it takes to reach a specified speed is proportional to the gross weight of the vehicle. That is, as the gross weight of the dump truck 1 (the loading weight of the cargo W) increases, the time it takes for the vehicle speed Vs of the dump truck 1 to reach the speed threshold Vth also increases. Therefore, it is preferred that the time threshold Tth is not a fixed value, but is set according to the change in the gross weight of the dump truck 1 (the loading weight of the cargo W).

[0102] Specifically, the elapsed time determination unit 43C receives the detection value of the pressure sensor 25 functioning as a load sensor, that is, the cylinder pressure Ps of the suspension 7, 8, and calculates the load weight of the cargo W or the total weight of the dump truck 1 including the load weight of the cargo W based on the detection value Ps of the pressure sensor 25. The time threshold Tth is set according to the load weight of the cargo W or the total weight of the dump truck 1 as the calculation result. That is, the elapsed time determination unit 43C is set in such a way that the time threshold Tth becomes longer as the load weight of the cargo W becomes larger. In addition, in the controller 30C of this embodiment, the functional units of the drive torque command unit 41, the engine speed determination unit 42, and the departure determination unit 44 other than the elapsed time determination unit 43C are the same as those in the first embodiment.

[0103] Next, use Fig. 9A control procedure of the controller of the electric transport vehicle according to the third embodiment when the vehicle starts will be described. Fig. 9 Yes means Figure 8 1 is a flowchart showing an example of a control procedure of a controller of an electric transport vehicle according to a third embodiment when the vehicle is started.

[0104] Fig. 9 The control sequence of the controller 30C of the third embodiment shown in FIG. 1 is different from the control sequence of the controller 30 of the first embodiment (see FIG. 1 ). Figure 3 ) is different in the following points. When the departure instruction of the dump truck 1 is input, after it is determined that the engine speed Ne is above the speed threshold Nth (after it is determined to be yes in step S30), the elapsed time judgment unit 43C sets the time threshold Tth according to the loading weight of the goods W or the total weight of the dump truck 1 (step S35). Thus, the time threshold Tth is set to increase as the loading weight of the goods W increases. Moreover, the elapsed time judgment unit 43C judges whether the measured elapsed time Ta exceeds the time threshold Tth set by step S35 (step S40C). In this case, because the time threshold Tth is set to increase as the loading weight of the goods W increases, it is possible to judge whether there is contact with the vehicle blocker 100 based on the time taken into account for the vehicle speed Vs of the dump truck 1 to accelerate until it reaches the speed threshold. In addition, the processing other than step S35 and step S40C (steps S10 to S30 and S50 to S60) is the same as that of the first embodiment.

[0105] According to the third embodiment described above, similarly to the first embodiment described above, after the time Ta (first elapsed time) from the time point when the engine speed Ne reaches the speed threshold Nth reaches the time threshold Tth, it is determined whether the vehicle speed Vs reaches the speed threshold Vth, thereby taking into account the acceleration time from the start of the movement of the dump truck 1 (electric transport vehicle) at the time of departure to the travel state detectable by the vehicle speed sensor 24 (speed sensor), it is possible to determine whether the dump truck 1 (electric transport vehicle) is in contact with the blocker 100 and is in a state where the vehicle cannot be started, thereby preventing errors in the determination. That is, it is possible to reliably determine whether the dump truck 1 (electric transport vehicle) is in a state where the vehicle cannot be started due to contact with the blocker 100 when the vehicle is started.

[0106] The dump truck 1 (electric transport vehicle) of this embodiment further includes a pressure sensor 25 as a load sensor for detecting the load weight of the cargo W. The time threshold Tth is set to be longer as the detection value of the pressure sensor 25 as the load sensor increases.

[0107] According to this configuration, the time threshold Tth is set according to the loading weight of the cargo W, and thus the time threshold Tth, as an index of the acceleration time from the start of the movement of the vehicle to the traveling state detectable by the vehicle speed sensor 24, becomes an appropriate value in consideration of the influence of the loading weight of the cargo W. Therefore, it is possible to reliably determine whether or not the vehicle is in a state of being unable to start due to contact with the vehicle blocker 100 when the vehicle starts.

[0108] [First Modification of the Third Embodiment]

[0109] Next, use Fig.10 An electric transport vehicle according to a first modified example of the third embodiment of the present invention will be described. Fig.10 In the Figures 1 to 9 The parts with the same reference numerals as shown are the same parts, and thus their detailed description is omitted. Fig.10 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a first modified example of the third embodiment and a controller that controls the electric travel system.

[0110] Fig.10 The electric transport vehicle of the first modified example of the third embodiment shown in FIG. 1 is different from the third embodiment in the following points. The elapsed time determination unit 43C of the controller 30C of the third embodiment sets the time threshold value Tth (see FIG. 1 ) based on the load weight of the cargo W of the dump truck 1 or the total weight of the dump truck 1 (the detection value Ps of the pressure sensor 25 as the load amount sensor). Figure 8 ). In contrast, the elapsed time determination unit 43D of the controller 30D according to the first modified example of the third embodiment changes the setting of the time threshold value Tth according to the difference in the running resistance of the road surface at the departure position of the dump truck 1.

[0111] If the driving resistance of the road surface at the starting position of the dump truck 1 is different, even if the electric motor 11 applies the same driving torque to the rear wheel 4, the time taken for the vehicle speed Vs of the dump truck 1 to reach the speed threshold Vth will also change. That is, as the driving resistance of the road surface becomes larger and larger, the time taken for the vehicle speed Vs of the dump truck 1 to reach the speed threshold Vth also becomes longer. Therefore, in order to correctly judge whether there is a state of being unable to start due to the contact of the dump truck 1 with the car blocker 100, it is preferred that the time threshold Tth for determining the time point of the judgment is not a fixed value, but is set according to the difference in the driving resistance of the road surface. As the driving resistance, the first one can cite the situation that the road surface slope at the starting position of the dump truck 1 is uphill relative to the traveling direction. The second one can cite the situation that if the road surface is soft due to muddy or the like, the squeezing resistance of the soil becomes larger when the wheels are running.

[0112] Therefore, the elapsed time determination unit 43D receives, for example, the detection value As of the acceleration sensor 26 functioning as a tilt sensor, that is, the inclination (road gradient) of the dump truck 1 relative to the horizontal plane, and calculates the gradient resistance as the driving resistance of the road surface according to the magnitude of the detection value As (road gradient) of the acceleration sensor 26, and sets the time threshold value Tth based on the gradient resistance as the calculation result. In addition, regarding the magnitude of the driving resistance based on the road surface state, such as the squeezing resistance of a muddy road, it is considered that the information Sr related to the road surface state at the work site, such as the rainfall amount at the site and the image data of the road surface state, can be obtained from the control station 60. The elapsed time determination unit 43D can also calculate the driving resistance of the road surface state based on the information Sr related to the road surface state input from the control station 60, and set the time threshold value Tth corresponding to the driving resistance of the road surface state as the calculation result. In addition, the time threshold value Tth can also be set based on the driving resistance based on the road surface gradient calculated based on the detection value of the acceleration sensor 26 and the driving resistance of the road surface state calculated based on the information Sr related to the road surface state input from the control station 60. Thus, whether or not the dump truck 1 is in a state where it cannot start due to contact with the stopper 100 can be accurately determined based on the magnitude of the running resistance of the road surface when the dump truck 1 starts.

[0113] In the controller 30D of the present embodiment, the function units of the drive torque command unit 41, the engine speed judgment unit 42, and the vehicle start judgment unit 44 other than the elapsed time judgment unit 43D are the same as those of the third embodiment. In addition, the vehicle start control sequence of the controller 30D of the first modified example of the third embodiment is different from that of the controller 30C of the third embodiment. Fig. 9 The control procedure shown is the same except that in step S35 the elapsed time determination unit 43D sets the time threshold value Tth based on the travel resistance at the starting position of the dump truck 1 .

[0114] According to the first modification of the third embodiment, similarly to the third embodiment, it is possible to reliably determine whether the dump truck 1 (electric transport vehicle) is unable to start due to contact with the vehicle stopper 100 when the vehicle starts.

[0115] In the present modification, the time threshold value Tth is set to be longer as the running resistance of the road surface increases.

[0116] According to this configuration, the time threshold Tth is set according to the running resistance of the road surface, and thus the time threshold Tth is an index of the acceleration time from the start of the vehicle's movement to the running state detectable by the vehicle speed sensor 24, and becomes an appropriate value considering the influence of the running resistance of the road surface. Therefore, it is possible to reliably determine whether the vehicle is in a state of being unable to start due to contact with the vehicle blocker 100 when the vehicle starts.

[0117] The dump truck 1 (electric transport vehicle) of this modification further includes an acceleration sensor 26 as a tilt sensor capable of detecting a road surface gradient. The road surface running resistance is a running resistance corresponding to a road surface gradient calculated based on the road surface gradient detected by the acceleration sensor 26 as a tilt sensor.

[0118] According to this configuration, the time threshold value Tth is an index of the acceleration time from the start of the vehicle movement to the point where the vehicle speed sensor 24 reaches a running state detectable, and is an appropriate value in consideration of the influence of the running resistance according to the road surface gradient.

[0119] In the present modification, the running resistance of the road surface is a running resistance according to the road surface state calculated based on the information Sr on the road surface state input from the control station 60 (external).

[0120] According to this configuration, the time threshold value Tth is an index of the acceleration time from the start of the vehicle movement to the travel state detectable by the vehicle speed sensor 24 and is an appropriate value in consideration of the influence of the travel resistance according to the road surface state such as a muddy road.

[0121] [Second variation of the third embodiment]

[0122] Next, use Fig.11 as well as Fig.12 An electric transport vehicle according to a second modified example of the third embodiment of the present invention will be described. Fig.11 as well as Fig.12 In the Figures 1 to 10 The parts with the same reference numerals as shown are the same parts, and thus their detailed description is omitted. Fig.11 This is a block diagram showing a schematic structure of an electric travel system in an electric transport vehicle according to a second modification of the third embodiment and a controller that controls the electric travel system.

[0123] Fig.11 The electric transport vehicle of the second modified example of the third embodiment shown in the figure is different from the third embodiment in the following points. The elapsed time determination unit 43C of the controller 30C of the third embodiment sets the time threshold value Tth (see the detection value Ps of the pressure sensor 25) according to the load weight of the cargo W of the dump truck 1 or the total weight of the dump truck 1. Figure 8 ). In contrast, the elapsed time determination unit 43E of the controller 30E of the second modified example of the third embodiment changes the setting of the time threshold Tth according to the length of the elapsed time Te taken from the input of the departure instruction until the engine speed Ne reaches the speed threshold Nth.

[0124] The torque of the engine 12 is not only used to increase the speed of the engine 12 itself, but also used to drive the generator 13 (to generate electricity). Therefore, depending on the size of the departure load of the dump truck 1, it may sometimes take a longer time for the engine speed to increase. As described above, the driving force required of the electric motor 11 increases depending on the size of the loading weight of the cargo W, the size of the ascending slope, and the driving resistance of the muddy road. If the driving force required of the electric motor 11 for the vehicle to start increases, the power generated by the generator 13 will also increase accordingly. In this case, the torque of the engine 12 used to drive the generator 13 will inevitably increase, and accordingly, the engine speed Ne is difficult to increase, and there is a tendency for the elapsed time taken to reach the specified value to become relatively longer.

[0125] Therefore, the elapsed time determination unit 43E of the controller 30E of the present modification measures the elapsed time Te taken from the input of the departure instruction until the engine speed Ne reaches the speed threshold value Nth, and sets the time threshold value Tth based on the elapsed time Te as the measurement result. Thus, unlike the case of the third embodiment and the case of the first modification thereof, the time threshold value Tth can be set taking into account the load weight of the cargo W and the road surface running resistance that affect the determination of whether the vehicle is to depart, without receiving the detection value Ps of the pressure sensor 25, the detection value As of the acceleration sensor 26, the information Sr related to the road surface state running resistance from the control station 60, and the like.

[0126] Next, use Fig.12 A control procedure at the time of vehicle departure by the controller of the electric transport vehicle according to the second modified example of the third embodiment will be described. Fig.12 Yes means Fig.11 1 is a flowchart showing an example of a control procedure at the time of starting the vehicle by a controller of an electric transport vehicle according to a second modification of the third embodiment shown in FIG.

[0127] Fig.12 The control sequence of the controller 30E of the second modified example of the third embodiment shown in FIG. 1 is different from the control sequence of the controller 30C of the third embodiment (see FIG. 1 ). Fig. 9) are different in the following points. When the departure instruction of the dump truck 1 is input, after the step S20 in which the driving torque instruction corresponding to the operating pedal 21 or the acceleration instruction of the control station 60 is output to the inverter 14, the elapsed time judgment unit 43E starts to measure the elapsed time Te of the increase of the engine speed Ne (step S27). Moreover, the elapsed time judgment unit 43E measures the elapsed time Te up to the time point when the engine speed Ne is judged to rise to the speed threshold Nth (yes in step S30), and sets the time threshold Tth based on the elapsed time Te of the measurement result (the elapsed time from the input time point of the departure instruction to the engine speed Ne reaching the speed threshold Nth) (step S35E). Thus, the time threshold Tth is set to become longer as the elapsed time Te spent until the engine speed Ne rises to the speed threshold Nth becomes longer. In this case, the time threshold Tth is set according to the loading weight and driving resistance of the cargo W, so it is possible to correctly judge whether there is a state of being unable to start due to the contact of the dump truck 1 with the car blocker 100. In addition, the processes other than steps S27 and S35E (steps S10 to S20, S30, and S40 to S60) are the same as those in the third embodiment.

[0128] According to the second modification of the third embodiment, similarly to the third embodiment, it is possible to reliably determine whether the dump truck 1 (electric transport vehicle) is unable to start due to contact with the vehicle stopper 100 when the vehicle starts.

[0129] In addition, in this modified example, the elapsed time determination unit 43E is further configured to measure the elapsed time Te (second elapsed time) from the time when the vehicle departure instruction is input to the time when the engine speed determination unit 42 determines that the detection value Ne of the speed sensor 23 is greater than the speed threshold value Nth. The above-mentioned time threshold value Tth is set to become longer as the measured elapsed time Te (second elapsed time) becomes longer.

[0130] According to this configuration, the time threshold value Tth is set based on the elapsed time Te taken for the engine speed Ne to rise to the speed threshold value Nth. Therefore, there is no need to use sensors for detecting the loading weight of the cargo W and the road slope, such as the pressure sensor 25 as an inclination sensor of the third embodiment and the acceleration sensor 26 of the first variant of the third embodiment. It is possible to set the time threshold value Tth, which is an indicator of the acceleration time from the start of the vehicle's movement to the driving state detectable by the vehicle speed sensor 24, to an appropriate value.

[0131] [Other embodiments]

[0132] In addition, the present invention is not limited to the first to third embodiments and their modifications, and includes various modifications. The above embodiments are described in detail to explain the present invention in an easy-to-understand manner, but are not limited to including all the structures described. For example, a part of the structure of a certain embodiment can be replaced with the structure of other embodiments, and the structure of other embodiments can be added to the structure of a certain embodiment. In addition, for a part of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0133] For example, the configurations of the second embodiment and its variants can be combined. That is, the engine speed determination unit of the controller can also be configured to change the setting of the speed threshold Nth based on two conditions: the loading weight of the cargo W of the dump truck 1 and the inclination state (road slope) at the starting position of the dump truck 1.

[0134] In addition, the configurations of the third embodiment and the first variation thereof can be combined. That is, the elapsed time determination unit of the controller can also be configured to change the setting of the time threshold Tth based on two conditions: the loading weight of the cargo W of the dump truck 1 and the driving resistance of the road surface at the starting position of the dump truck 1.

[0135] In addition, the configuration of the second embodiment or its variant can be combined with the configuration of the third embodiment or its first variant. That is, the engine speed determination unit of the controller can be configured to change the setting of the speed threshold Nth according to at least one of the two conditions: the loading weight of the cargo W of the dump truck 1 and the tilt state (road gradient) at the starting position of the dump truck 1, and the elapsed time determination unit of the controller can be configured to change the setting of the time threshold Tth according to at least one of the two conditions: the loading weight of the cargo W of the dump truck 1 and the driving resistance of the road at the starting position of the dump truck 1.

[0136] In addition, the configuration of the second embodiment or its modified example can be combined with the configuration of the second modified example of the third embodiment. That is, the engine speed determination unit of the controller can be configured to change the setting of the speed threshold Nth according to at least one of the two conditions of the loading weight of the cargo W of the dump truck 1 and the tilt state (road gradient) at the starting position of the dump truck 1, and the elapsed time determination unit of the controller can be configured to change the setting of the time threshold Tth according to the length of the elapsed time Te taken for the engine speed Ne to reach the speed threshold Nth.

[0137] In addition, each function of the controllers 30 , 30A, 30B, 30C, 30D, and 30E in the above-described embodiment may be partially or entirely realized by hardware, for example, by integrated circuit design.

[0138] In the above embodiment, the electric motor 11 is exemplified as an induction motor. However, the present invention can be applied even if the electric motor 11 is a synchronous motor.

[0139] Description of Reference Numerals

[0140] 1…dump truck (electric transport vehicle), 11…electric motor, 12…engine, 13…generator, 23…rotation speed sensor, 24…vehicle speed sensor (speed sensor), 25…pressure sensor (load amount sensor), 26…acceleration sensor (tilt sensor), 30, 30A, 30B, 30C, 30D, 30E…controller, 42, 42A, 42B…engine rotation speed determination unit, 43, 43C, 43D, 43E…elapsed time determination unit, 44…departure determination unit, 60…control station (external), W…cargo, Nth…rotation speed threshold value, Tth…time threshold value, Vth…speed threshold value, Ta…elapsed time (first elapsed time), Te…elapsed time (second elapsed time).

Claims

1. An electric transport vehicle having: engine; a generator mechanically driven by the engine; an electric motor driven by electric power supplied from the generator; a rotation speed sensor for detecting the rotation speed of the engine; a speed sensor to detect the speed of the vehicle; and a controller for controlling the driving of the electric motor, The electric transport vehicle is driven by the driving force of the electric motor to transport cargo, and is characterized in that: The controller has: an engine speed determination unit, which, when a vehicle departure instruction is input, determines whether a detection value of the speed sensor is greater than a speed threshold; an elapsed time determination unit that measures a first elapsed time from a time point when the engine speed determination unit determines that the detection value of the speed sensor is equal to or greater than the speed threshold, and determines whether the first elapsed time has reached a time threshold; and a departure determination unit that determines whether the detection value of the speed sensor is equal to or greater than a speed threshold after the elapsed time determination unit determines that the first elapsed time has reached the time threshold, The controller stops the electric motor when the vehicle departure determination unit determines that the detection value of the speed sensor is less than the speed threshold value.

2. The electric transport vehicle according to claim 1, characterized in that: further comprising a load sensor for detecting the load weight of the cargo, The rotation speed threshold is set to become higher as the detection value of the load sensor becomes larger.

3. The electric transport vehicle according to claim 1, characterized in that: It further has a tilt sensor capable of detecting the slope of the road surface, The rotation speed threshold is set to become higher as the detection value of the tilt sensor becomes larger when the vehicle travel direction of the vehicle departure instruction is an uphill direction.

4. The electric transport vehicle according to claim 1, characterized in that: further comprising a load sensor for detecting the load weight of the cargo, The time threshold is set to be longer as the detection value of the load amount sensor becomes larger.

5. The electric transport vehicle according to claim 1, characterized in that: The time threshold is set to be longer as the running resistance of the road surface increases.

6. The electric transport vehicle according to claim 5, characterized in that: It further has a tilt sensor capable of detecting the slope of the road surface, The running resistance of the road surface is a running resistance calculated based on the road surface gradient detected by the inclination sensor.

7. The electric transport vehicle according to claim 5, characterized in that: The road surface running resistance is a running resistance calculated based on information on the road surface state input from the outside.

8. The electric transport vehicle according to claim 1, characterized in that: The elapsed time determination unit is further configured to measure a second elapsed time from when the vehicle departure instruction is input to when it is determined that the detection value of the rotation speed sensor is equal to or greater than the rotation speed threshold value, The time threshold becomes longer as the measured second elapsed time becomes longer.

Images