Transport vehicle

Abstract

This transport vehicle comprises: an engine; a generator driven by the engine to generate power; a travel motor driven with the power generated by the generator; a cab provided with an accelerator pedal for adjusting the rotational speed of the engine through an operation by an operator; and a controller for controlling the engine and the travel motor. The transport vehicle has a work mode changeover switch capable of switching between a plurality of work modes having different engine outputs. The controller controls the engine or the travel motor by changing operation parameters of the engine and the travel motor corresponding to the amount of depression of the accelerator pedal, in accordance with the work mode set by the work mode changeover switch.

Description

Transport vehicle

[0001] The present invention relates to a transport vehicle such as a dump truck for transporting minerals excavated from a mine.

[0002] For transport vehicles, reducing fuel consumption is an issue in order to improve life cycle costs. Common methods for reducing fuel consumption include reducing engine speed and installing an auxiliary power source for the engine. Also known is a method of controlling engine output based on the load during travel (travel load). For example, Patent Document 1 proposes a control method for a work vehicle (dump truck) that transports cargo, in which the engine output and the gear shift point of the transmission are switched based on the vehicle load, such as work conditions and road conditions.

[0003] Patent No. 2520623 specification

[0004] The prior art described in Patent Document 1 detects the load during travel based on changes in the vehicle's total body mass, i.e., the presence or absence of a load, and shifts gears accordingly. Therefore, it cannot be applied to electric work vehicles that run on a motor and do not have a gear shifting mechanism. Furthermore, even if a transmission is used, the control method does not take into account the amount of work, which results in longer work time, i.e., engine operating time, which makes it impossible to reduce fuel consumption. Here, in the case of a dump truck, the amount of work is the amount of transportation per unit time.

[0005] Furthermore, there are two problems at mining sites. The first is that multiple dump trucks with different engine outputs travel on the same route, so even if only one truck travels at high speed, the waiting time for loading increases, making it impossible to increase the amount of work and resulting in increased fuel consumption. The second is that each driver (operator) steps on the accelerator in a different way, which means that from the perspective of the mine site manager, there is a variance in the relationship between the amount of work and fuel consumption for each operator, making optimal fleet management impossible.

[0006] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a transport vehicle that enables optimal fleet management at mining sites and the like, achieving both improved work volume and reduced fuel consumption.

[0007] In order to solve the above problems, the transport vehicle of the present invention is a transport vehicle comprising an engine, a generator driven by the engine to generate electricity, a traveling motor driven by the electricity generated by the generator, a cab provided with an accelerator pedal that is operated by the operator to adjust the engine speed, and a controller that controls the engine and traveling motor, wherein the transport vehicle has a work mode changeover switch that can be switched between multiple work modes with different engine outputs, and the controller controls the engine or traveling motor by switching the operating parameters of the engine and traveling motor corresponding to the amount of depression of the accelerator pedal depending on the work mode set by the work mode changeover switch.

[0008] According to the present invention, even when multiple dump trucks with different engine outputs are traveling along the same course at a work site, optimal engine output control is possible, enabling both increased workload and reduced fuel consumption. Furthermore, the relationship between workload and fuel consumption is less variable between operators, enabling optimal fleet management. Further features related to the present invention will become apparent from the description of this specification and the accompanying drawings. Furthermore, problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0009] 1 is a schematic diagram showing the overall configuration of a mining dump truck. 2 is a block diagram showing an overview of a work mode switching system mounted on the dump truck. 3 is an iso-fuel consumption map for the engine. 4 is a diagram showing engine speed and engine output for each work mode. 5 is a diagram showing the relationship between engine speed, distance fuel consumption, and climbing speed for each work mode. 6 is a schematic diagram showing the interior of the cab of the dump truck. 7 is a diagram showing information displayed on a display inside the cab. 8 is a flowchart showing the processing executed by the work mode switching system.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an increase in the work load and a reduction in fuel consumption of a transport vehicle, and in this embodiment, an electric dump truck for mining use will be described as an example.

[0011] 1, a mining dump truck (transport vehicle) 100 is configured to include a frame 1 forming the main body, a bed 2 on which transported objects 5 such as earth and sand are loaded, front tires (wheels) 3F and rear tires (wheels) 3R, an engine 4 mounted on the front part of the frame 1 as a prime mover serving as a power source for traveling, a generator 6 directly connected to the engine 4, a control cabinet 7 for controlling the power generated by the generator 6, a travel motor 8 directly connected to the wheels, and a cab 9. The cab 9 forms a driver's cabin in which an operator who operates the dump truck 100 sits.

[0012] Fig. 2 is a block diagram showing an outline of a work mode switching system mounted on a dump truck. In this embodiment, the work mode switching system includes an accelerator pedal 10, an accelerator pedal depression amount sensor 11, a controller 12, an engine speed control device 13, and a changeover switch (work mode changeover switch) 14, all of which are provided in the cab 9, in addition to the components shown in Fig. 1.

[0013] An accelerator pedal depression amount sensor 11 detects the depression amount of the accelerator pedal 10 and outputs the detected value to a controller 12 mounted in the cab 9. The controller 12 outputs a calculation result according to the output of the accelerator pedal depression amount sensor 11 to an engine speed control device 13. The engine speed control device 13 controls the engine speed based on the accelerator depression amount. In addition, a generator 6 directly connected to the engine 4 sends the generated electric power to a control cabinet 7. A current control device 7a in the control cabinet 7 controls the electric current received by the control cabinet 7 and outputs it to a traveling motor 8. When the traveling motor 8 is driven, the wheels 3 rotate and the dump truck 100 travels.

[0014] Even for the same accelerator pedal 10 depression amount, the engine 4 rotation speed corresponding to the output of the accelerator pedal depression amount sensor 11 varies depending on the work mode. The work mode is switched by the controller 12. Specifically, while traveling, the operator operates the selector switch 14 depending on the road conditions and work conditions, and the controller 12 outputs a signal to the engine rotation speed control device 13 to switch the work mode, controls the engine rotation speed to the setting for each work mode, and changes the output of the travel motor 8 for each engine rotation speed. The engine 4 has an iso-fuel efficiency map, as shown in Figure 3, for example, which shows the fuel consumption rate from the engine rotation speed and engine output. Note that the numerical values ​​written on the iso-fuel efficiency line in Figure 3 indicate the fuel efficiency.

[0015] By setting the engine speed and motor output in a region where the fuel consumption rate is low, i.e., where fuel economy is good, based on the engine fuel economy map, it is possible to set a work mode that achieves both improved work volume and fuel economy. Figure 4 shows an example of work mode settings, with HP mode set in a region where the engine speed and output are high, i.e., where fuel economy is high, E mode set in a region where the engine speed and output are low, i.e., where fuel economy is low, and P mode set in between. Details of these work modes will be described later.

[0016] Here, the driving load of a dump truck varies depending on whether or not it is loaded, the depression amount of the accelerator pedal 10, the road surface condition, and the angle of incline on which it is traveling. Conditions where the driving load is high include traveling with a load, accelerating, traveling on a rough road, and traveling uphill. When the driving load is high, it is necessary to increase the engine output, while when the driving load is low, it is not necessary to increase the engine output. In the present invention, the operator selects the HP (High Power) mode when the driving load is high and priority is given to the workload; the P (Power) mode when the driving load is high and priority is not given to the workload; and the E (Economy) mode when the driving load is low and priority is given to reducing fuel consumption. For example, when traveling uphill with a load and there is no preceding vehicle, the HP mode is used; when traveling uphill with a load and the preceding vehicle is waiting to unload or load, the P mode is used; and when traveling on a flat road with no load, the E mode is used. That is, there are three work modes: an HP mode that prioritizes increasing the amount of work, an E mode that prioritizes fuel economy, and a P mode that achieves both an increase in the amount of work and fuel economy.

[0017] FIG. 5 is a diagram showing the relationship between engine speed, distance fuel consumption, and climbing speed in the three work modes. The engine speed for each of the three work modes is determined based on this diagram. In the HP mode, which aims to increase the amount of work, the climbing speed is set to the highest speed, i.e., the engine output is set to the maximum, and the engine speed A [min －１ In the E mode, which is aimed at reducing fuel consumption, the distance fuel consumption is in the minimum range, and the climbing speed is relatively high in absolute terms but is slow compared to other work modes, and the engine rotation speed C [min －１ In the P mode, which aims to achieve both work volume and fuel economy, the climbing speed and distance fuel economy are intermediate between the HP mode and the E mode, and the engine revolutions B [min －１ ] and set it as follows.

[0018] Various parameters must be adjusted for each work mode, and there are four types of parameters that can be adjusted, as described below. (1) High Idle Engine Speed: This parameter determines the engine speed when the accelerator pedal 10 is fully depressed. Therefore, it particularly affects the driving performance when climbing slopes, which uses the maximum output of the engine 4, while also affecting fuel economy. For example, the high idle engine speed is set to its lowest in E mode, its highest in HP mode, and somewhere in between in P mode. (2) Engine Output Ratio Limit: To improve the acceleration (speedup) of the engine 4, electric dump trucks sometimes have a mechanism for switching to an operating mode (acceleration mode) that limits the main generator absorption horsepower when the engine speed increases. By limiting the main generator absorption horsepower, the output of the engine 4 is allocated to increasing the engine speed, thereby improving the acceleration of the engine 4. The engine output ratio limit (acceleration) is a ratio that determines the main generator absorption horsepower in acceleration mode. In other words, the engine output ratio limit is a parameter that determines how much of the power (explosive force) generated by the engine 4 is allocated to the output of the traction motor 8 when the engine speed (target speed) corresponding to the depression of the accelerator pedal 10 differs from the actual speed (e.g., when the actual speed is lower than the target speed), thereby determining how much (i.e., the remaining power) is allocated to increasing the engine speed. For example, the engine output ratio limit is set to its lowest in E mode, its highest in HP mode, and an intermediate value in P mode. (3) Motor Input Upper Limit The role of this parameter is to limit the absorbed horsepower when the accelerator pedal opening is small in order to improve fine operability. In other words, the motor input upper limit is a limit on the output of the traction motor 8 when the depression of the accelerator pedal 10 (and the corresponding engine speed) is below a predetermined amount (e.g., less than 80%). For example, the motor input upper limit is set to its highest in E mode, its lowest in HP mode, and an intermediate value in P mode. For example, when the accelerator pedal 10 is depressed only slightly, such as when the vehicle is traveling at a constant speed on flat ground, the output of the travel motor 8 is greatly restricted in the E mode.This allows the vehicle to travel under output conditions (such as the relationship between engine speed and motor output) that are expected to improve fuel efficiency, regardless of accelerator operation. (4) Standard Engine Output The role of this parameter is to control the maximum main generator absorption horsepower (upper limit of output of travel motor 8) that corresponds to the engine 4 rotation speed. Standard engine output is set to the lowest in E mode, the highest in HP mode, and somewhere in between in P mode. In current models, the total engine output (= standard engine output + absorption horsepower of the auxiliary generator, hydraulic pump, and 24V generator) is set to the rated output of engine 4.

[0019] By appropriately changing the above parameters, it is possible to set the three work modes described above. In other words, the controller 12 adjusts at least one of the above parameters in three stages depending on the work mode. The controller 12 may adjust two, three, or all of the above parameters in three stages depending on the work mode.

[0020] 6 is a schematic diagram showing the interior of the cab 9 as seen from the operator's perspective. An accelerator pedal 10 is provided inside the cab 9, which is operated by the operator to adjust the rotation speed of the engine 4. A selector switch 14 is also provided inside the cab 9 for switching between work modes when operated by the operator. The selector switch 14 may be of any type, such as a dial type, a push button type, or a lever type. A display 20 is also provided inside the cab 9 to display various information.

[0021] Figure 7 is a diagram showing information displayed on the display 20 inside the cab 9. As shown in Figure 7, the display 20 inside the cab 9 displays various information that are conditions for selecting a work mode, such as the vehicle speed and load information, and the current work mode is displayed in the work mode display section 15 located in the center of the tachometer that shows the RPM of the engine 4. By providing the display 20 inside the cab 9 that displays the work mode in this way, the operator can easily check the current work mode. Furthermore, the operator can change the work mode as needed by referring to the various information displayed on the display 20.

[0022] 8 is a flowchart showing the processing executed in this embodiment. The flow starts by starting up the transport vehicle 100. Next, the mine management company or the vehicle driver (operator) selects a work mode (S1).

[0023] If priority is given to increasing the amount of work in S1, the HP mode is selected as the work mode, and the transporter vehicle 100 continues traveling in the HP mode until the next operation instruction is received (S2).

[0024] If a balance between work volume and fuel economy is prioritized in S1, P mode is selected as the work mode (S3). Thereafter, while traveling in P mode, it is determined whether or not P mode travel can be maintained (S4). If it is determined in S4 that P mode cannot be maintained while traveling in P mode (for example, due to a stall while climbing a slope), the work mode is switched to HP mode (S5). Then, while traveling in HP mode, it is determined whether or not P mode travel is possible (S6). If it is determined in S6 that P mode travel is impossible, HP mode travel is maintained in S5. If the traveling conditions change in S6 (such as stopping the vehicle or a decrease in engine load rate due to completion of climbing a slope) and it is determined that P mode travel is possible again, the work mode is switched to P mode (S7).

[0025] If fuel economy is prioritized in S1, E mode is selected as the work mode (S8). Thereafter, as in P mode, it is determined whether or not E mode driving can be maintained (S9). If it is determined in S9 that E mode cannot be maintained while driving in E mode (for example, due to a stall while climbing a slope), the work mode is switched to P mode (S10). While driving in P mode, it is determined whether or not P mode driving can be maintained (S11). If it is determined in S11 that P mode cannot be maintained while driving in P mode (for example, due to a stall while climbing a slope), the work mode is switched to HP mode (S12). While driving in HP mode, it is determined whether or not P mode driving is possible (S13). If it is determined in S13 that P mode driving is impossible, HP mode driving is maintained in S12. If the driving conditions change in S13 (such as stopping, a decrease in the engine load factor due to completion of climbing, etc.) and it is determined that driving in P mode is possible again, the work mode is switched to P mode in S10.

[0026] In S11, if the driving conditions change (such as stopping, a decrease in the engine load rate due to completion of a hill climb, etc.) and it becomes possible to drive in E mode again, it is determined whether or not driving in E mode is possible (S14). If it is determined in S14 that driving in E mode is not possible, driving in P mode is maintained in S10. In S14, if the driving conditions change (such as stopping, a decrease in the engine load rate due to completion of a hill climb, etc.) and it becomes possible to drive in E mode again, the work mode is switched to E mode (S15).

[0027] As described above, according to this embodiment, by switching the work mode depending on the road conditions at the customer mine site and the work conditions such as whether or not there are vehicles waiting to be loaded, it is possible to operate the vehicle while achieving both a high workload and reduced fuel consumption.

[0028] In the above embodiment, three types of work modes have been described: HP mode, P mode, and E mode. In other words, in the above embodiment, there are at least three work modes that prioritize improving work volume and / or fuel efficiency. However, in addition to these, a work mode called a custom mode can also be adopted.

[0029] Specifically, the custom mode refers to an operation mode optimized for each mine site. In other words, since the route of the transport vehicle 100 is determined for each mine site, it is possible to set an appropriate operation mode along that route as the custom mode.

[0030] The above-described embodiment of the present invention provides the following advantageous effects.

[0031] (1) A transport vehicle 100 according to an embodiment of the present invention is a transport vehicle 100 comprising an engine 4, a generator 6 driven by the engine 4 to generate electricity, a traveling motor 8 driven by the electricity generated by the generator 6, a cab 9 provided with an accelerator pedal 10 that adjusts the rotation speed of the engine 4 by operation of the operator, and a controller 12 that controls the engine 4 and the traveling motor 8. The transport vehicle 100 has a work mode changeover switch 14 that can be switched between multiple work modes with different outputs of the engine 4, and the controller 12 controls the engine 4 or the traveling motor 8 by switching the operating parameters of the engine 4 and the traveling motor 8 corresponding to the amount of depression of the accelerator pedal 10, depending on the work mode set by the work mode changeover switch 14.

[0032] With the above configuration, it is possible to provide a transport vehicle 100 that enables optimal fleet management at mining sites and the like, achieving both improved work volume and reduced fuel consumption.

[0033] (2) The controller 12 switches between operating parameters according to the work mode using one of the following: a high idle engine speed, which is a parameter that defines the engine speed when the accelerator pedal 10 is depressed to 100%; an engine output ratio limit, which is a parameter that defines how much of the power generated by the engine 4 is allocated to the output of the travel motor 8 when the engine 4 speed corresponding to the accelerator pedal 10 depression amount differs from the actual engine speed; a motor input upper limit, which is a parameter that defines the limit amount of the output of the travel motor 8 when the accelerator pedal 10 depression amount is equal to or less than a predetermined amount; and a standard engine output, which is a parameter that defines the upper limit of the output of the travel motor 8 corresponding to the engine 4 speed.

[0034] With the above configuration, it is possible to set the work mode by appropriately changing the above operation parameters.

[0035] (3) The work modes include at least three modes that prioritize work volume improvement and / or fuel efficiency. By incorporating these work modes, the effect of (1) can be concretely achieved.

[0036] (4) The work modes include an HP mode that prioritizes increasing the amount of work, a P mode that balances increasing the amount of work with fuel economy, and an E mode that prioritizes reducing fuel economy. It is preferable that the modes include these work modes.

[0037] (5) The cab 9 is further provided with a display 20 capable of displaying conditions required for selecting a work mode. This allows the operator of the transport vehicle 100 to select an appropriate work mode while checking various information.

[0038] It should be noted that the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to embodiments that include all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete part of the configuration of each embodiment, or to add or replace other configurations.

[0039] 1 Frame (body), 6 Generator, 8 Travel motor, 9 Cab, 12 Controller, 14 Changeover switch (work mode changeover switch), 20 Display, 100 Dump truck

Claims

1. A transport vehicle comprising: an engine; a generator driven by the engine to generate electricity; a travel motor driven by the electricity generated by the generator; a cab provided with an accelerator pedal that can be operated by an operator to adjust the engine speed; and a controller that controls the engine and the travel motor, wherein the transport vehicle has a work mode changeover switch that can be switched between a plurality of work modes with different engine outputs, and the controller controls the engine and the travel motor by changing the operating parameters of the engine or the travel motor corresponding to the amount of depression of the accelerator pedal according to the work mode set by the work mode changeover switch.

2. A transport vehicle as described in claim 1, wherein the controller uses, as the operating parameter switched according to the work mode, one of the following: a high idle engine speed, which is a parameter that defines the engine speed when the accelerator pedal is depressed to 100%; an engine output ratio limit, which is a parameter that defines how much of the power generated by the engine is to be distributed to the output of the travel motor when the engine speed corresponding to the accelerator pedal depression amount differs from the actual engine speed; a motor input upper limit, which is a parameter that defines the limit amount of the output of the travel motor when the accelerator pedal depression amount is equal to or less than a predetermined amount; and a standard engine output, which is a parameter that defines the upper limit of the output of the travel motor corresponding to the engine speed.

3. A transport vehicle according to claim 1, characterized in that the work modes include at least three work modes that prioritize improvement in work volume and / or fuel efficiency.

4. A transport vehicle as described in claim 1, characterized in that the work modes include an HP mode that prioritizes increasing the amount of work, a P mode that balances increasing the amount of work with fuel efficiency, and an E mode that prioritizes reducing fuel efficiency.

5. A transport vehicle according to claim 1, further comprising a display in the cab that is capable of displaying the conditions required to select the work mode.

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