Dump truck

Abstract

To provide a dump truck improved in fuel efficiency by effectively utilizing engine output during soil dumping.SOLUTION: A dump truck is equipped with: a vehicle body; a loading platform; an engine; a main generator that generates electric power by driving force of the engine; a hydraulic pump that outputs hydraulic oil by driving force of the engine; a travelling motor that rotates a tire by electric power generated by the main generator; a hoist cylinder that makes the loading platform rise and fall by hydraulic oil outputted from the hydraulic pump; a storage battery that stores electric power; and a controller that when electric power stored in the storage battery is less than a threshold electric power (S14:Yes) in a period of time during which hydraulic oil for erecting the loading platform is supplied to the hoist cylinder (S12:Yes), stores, in the storage battery, electric power generated by the main generator (S15).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a dump truck equipped with a storage battery. [Background technology]

[0002] Conventionally, dump trucks have been known that include a vehicle body that travels by rotating tires, a loading platform that is supported on the vehicle body so that it can be raised and lowered, an engine that generates driving force, a generator that generates electricity using the driving force of the engine, a hydraulic pump that outputs hydraulic oil using the driving force of the engine, a travel motor that rotates the tires using the electricity generated by the generator, a hoist cylinder that raises and lowers the loading platform relative to the vehicle body using the hydraulic oil output from the hydraulic pump, and a storage battery that stores electricity (see, for example, Patent Document 1).

[0003] In the dump truck with the above configuration, the drive circuit is designed so that the hoist cylinder extension speed is optimal when the engine is running at full speed. The first reason is that if the hoist cylinder extension speed is designed to be optimal when the engine is running at low speed, the hydraulic pump capacity must be increased. The second reason is that if a speed-up gear is inserted between the engine and the hydraulic pump, the mass of the dump truck increases, reducing transport efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-299901 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the output of the hydraulic pump is very small, the conventional configuration in which the engine is rotated at full speed when the hoist cylinder is extended (i.e., when releasing soil) does not make effective use of the engine output, and there is a problem of poor fuel efficiency.

[0006] The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a dump truck that effectively utilizes engine output during soil dumping to improve fuel efficiency. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a dump truck comprising a vehicle body that travels by rotating tires, a loading platform supported on the vehicle body so as to be able to be raised and lowered, an engine that generates driving force, a main generator that generates electricity by the driving force of the engine, a hydraulic pump that outputs hydraulic oil by the driving force of the engine, a travel motor that rotates the tires by the electricity generated by the main generator, a hoist cylinder that raises and lowers the loading platform relative to the vehicle body by the hydraulic oil output from the hydraulic pump, and a storage battery that stores electricity, wherein the electricity stored in the storage battery is used to raise and lower the loading platform relative to the vehicle body while hydraulic oil for raising the platform is supplied to the hoist cylinder. , which is set to a value that can ensure a free capacity for storing the power generated by the main generator until the raising of the loading platform is completed. When the power is less than the threshold power, the power generated by the main generator is stored in the storage battery. and stopping the main generator when the power stored in the storage battery is equal to or greater than the threshold power while hydraulic oil for raising the loading platform is being supplied to the hoist cylinder. The present invention is characterized by comprising a controller for [Effects of the Invention]

[0008] According to the present invention, it is possible to effectively utilize the engine output during soil dumping, thereby improving fuel efficiency. Note that problems, configurations, and effects other than those described above will become clear from the following description of the embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view of a dump truck according to an embodiment of the present invention. [Figure 2] FIG. 2 is a circuit diagram of a drive circuit mounted on a dump truck. [Figure 3] FIG. 1 is a circuit diagram of a hydraulic circuit mounted on a dump truck. [Figure 4] FIG. 2 is a hardware configuration diagram of the dump truck. [Figure 5] 4 is a flowchart of a charge / discharge control process. [Figure 6] 10 is a flowchart of a normal driving process. [Figure 7] FIG. 10 is a diagram showing a drive circuit according to a first modification. [Figure 8] FIG. 10 is a diagram showing a drive circuit according to a second modification. [Figure 9] FIG. 10 is a diagram showing a drive circuit according to a third modification. [Figure 10] FIG. 10 is a diagram showing a drive circuit according to a fourth modification. [Figure 11] 6 is a flowchart of a process executed by the controller 30 according to a fourth modification, in place of the process enclosed by the dashed line in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of a dump truck according to the present invention will be described with reference to the drawings. Fig. 1 is a side view of a dump truck 1 according to this embodiment. Note that, unless otherwise specified, front, back, left, and right in this specification are based on the viewpoint of an operator who is on board and operating the dump truck 1.

[0011] As shown in FIG. 1, the dump truck 1 according to this embodiment mainly comprises a body frame 2, a pair of front tires 3L, 3R rotatably supported on both the left and right ends of the front of the body frame 2, a pair of rear tires 4L, 4R rotatably supported on both the left and right ends of the rear of the body frame 2, a loading platform 5 supported on the body frame 2 so that it can be raised and lowered, and a cab 6 in which an operator who operates the dump truck 1 rides.

[0012] The pair of front tires 3L, 3R are steered wheels whose steering angle changes in response to steering operation by the operator. Meanwhile, the pair of rear tires 4L, 4R are drive wheels that rotate when the driving force of travel motors 15L, 15R (see FIG. 2) is transmitted to them. The dump truck 1 is equipped with a pair of travel motors 15L, 15R to transmit driving force independently to each of the pair of rear tires 4L, 4R.

[0013] The loading platform 5 rises and falls vertically around a hinge pin 8 at the rear of the body frame 2 as the hoist cylinders 7L, 7R extend and retract. One end of the hoist cylinders 7L, 7R is connected to the body frame 2, and the other end is connected to the loading platform 5, and the hoist cylinders 7L, 7R extend and retract with hydraulic oil supplied from a hydraulic pump 22 (see Figures 2 and 3). When the hoist cylinders 7L, 7R extend, the loading platform 5 stands up, and when the hoist cylinders 7L, 7R contract, the loading platform 5 falls down.

[0014] The cab 6 is disposed at the left end on the deck 9 at the front end of the body frame 2. The cab 6 forms a driver's cab in which an operator who operates the dump truck 1 sits. Inside the cab 6, an operating device 6a (see FIG. 4) for operating the dump truck 1 is disposed. When the operator sitting in the cab 6 operates the operating device 6a, the dump truck 1 travels (accelerates, brakes, turns) and the loading platform 5 is raised and lowered.

[0015] The operation device 6a outputs an operation signal according to an operation by a user to a controller 30 (see FIG. 4) described later. The operation device 6a includes, for example, an accelerator pedal, a brake pedal, a steering wheel, a travel lever, and a hoist lever.

[0016] The accelerator pedal is an operating device that commands the acceleration of the dump truck 1. The brake pedal is an operating device that commands the braking of the dump truck 1. The steering is an operating device that commands the turning direction of the dump truck 1. The travel lever is an operating device that commands the traveling direction (forward position, reverse position, neutral position) of the dump truck 1 when the accelerator pedal is depressed. The hoist lever is an operating device that commands the raising and lowering of the loading platform 5 (upright position, tilted position).

[0017] In addition, a drive circuit 10 that drives the dump truck 1 and a hydraulic circuit 20 that drives hydraulic actuators (hoist cylinders 7L, 7R) are arranged below the deck 9. Furthermore, a grid box 17 (see FIG. 2) and a blower (not shown) that supplies cooling air to the grid box 17 are installed on the deck 9.

[0018] 2 is a circuit diagram of a drive circuit 10 mounted on the dump truck 1. The drive circuit 10 mainly includes an engine 11, a main generator 12, a rectifier 13, inverters 14L and 14R, travel motors 15L and 15R, a chopper 16, a grid box 17, a charge / discharge controller 18, and a storage battery 19, for example.

[0019] The engine 11 burns fuel to generate driving force for driving the dump truck 1. The main generator 12 is connected to the output shaft of the engine 11. The driving force of the engine 11 is transmitted to the main generator 12, which generates three-phase AC power. The rectifier 13 converts the three-phase AC power output from the main generator 12 into DC power and outputs it to the inverters 14L, 14R.

[0020] The inverters 14L, 14R convert the DC power output from the rectifier 13 or the DC power discharged from the storage battery 19 via the charge / discharge controller 18 into three-phase AC power and output it to the travel motors 15L, 15R. The travel motors 15L, 15R rotate by receiving the three-phase AC power from the inverters 14L, 14R. The rotational driving force of the travel motors 15L, 15R is transmitted to the rear tires 4L, 4R via reducers (not shown), causing the dump truck 1 to travel (accelerate).

[0021] On the other hand, when braking the dump truck 1, the traveling motors 15L, 15R operate as electric brakes. The traveling motors 15L, 15R operating as electric brakes generate regenerative power and output it to the inverters 14L, 14R. The inverters 14L, 14R convert the three-phase AC regenerative power output from the traveling motors 15L, 15R into DC power and output it to the chopper 16 and the charge / discharge controller 18.

[0022] The chopper 16 supplies the electric power output from the inverters 14L, 14R to the grid box 17 during regeneration of the dump truck 1. The grid box 17 is a resistor that converts the regenerative electric power generated by the traveling motors 15L, 15R into heat and consumes it.

[0023] The charge / discharge controller 18 controls the charge / discharge of the storage battery 19 in accordance with the control of the controller 30. More specifically, the charge / discharge controller 18 outputs (discharges) the electric power stored in the storage battery 19 to the inverters 14L, 14R when the dump truck 1 is powered (for example, when accelerating). On the other hand, the charge / discharge controller 18 stores the regenerated electric power output from the inverters 14L, 14R in the storage battery 19 when the dump truck 1 is regenerated (for example, when braking).

[0024] The drive circuit 10 also includes a rotation speed sensor 11a and a remaining amount sensor 19a. The rotation speed sensor 11a detects the rotation speed R of the engine 11 and outputs a rotation speed signal indicating the detection result to the controller 30. The remaining amount sensor 19a detects the amount of power stored in the storage battery 19 (hereinafter referred to as "remaining battery amount Q") and outputs a remaining amount signal indicating the detection result to the controller 30.

[0025] 3 is a circuit diagram of a hydraulic circuit 20 mounted on the dump truck 1. The hydraulic circuit 20 mainly includes a hydraulic oil tank 21, a hydraulic pump 22, and a directional control valve 23.

[0026] The hydraulic oil tank 21 stores hydraulic oil. The hydraulic pump 22 is connected to the output shaft of the engine 11. The hydraulic pump 22 outputs the hydraulic oil stored in the hydraulic oil tank 21 to the directional control valve 23 using the driving force generated by the engine 11. The hydraulic pump 22 is a variable displacement hydraulic pump whose discharge capacity can be changed by a regulator 22a.

[0027] The direction switching valve 23 supplies and discharges the hydraulic oil output from the hydraulic pump 22 to the hoist cylinders 7L, 7R under the control of the controller 30. The direction switching valve 23 is switched among positions A, B, and C by applying a control voltage from the controller 30 to a pair of electrodes 23a, 23b.

[0028] Position A is a position that blocks the supply and discharge of hydraulic oil to the hoist cylinders 7L, 7R. Position B is a position that supplies hydraulic oil to the bottom chambers of the hoist cylinders 7L, 7R and discharges it from the rod chambers. Position C is a position that supplies hydraulic oil to the rod chambers of the hoist cylinders 7L, 7R and discharges it from the bottom chambers.

[0029] The initial position of the direction switching valve 23 is position A. At this time, the extension and retraction of the hoist cylinders 7L, 7R stops and the direction switching valve 23 is held at its current position. Furthermore, the direction switching valve 23 is switched from position A to position B by applying a control voltage to the electrode 23a. This causes the hoist cylinders 7L, 7R to extend, and the platform 5 to rise. Furthermore, the direction switching valve 23 is switched from position A to position C by applying a control voltage to the electrode 23b. This causes the hoist cylinders 7L, 7R to contract, and the platform 5 to fall down. On the other hand, when the application of the control voltage to the electrodes 23a, 23b stops, the direction switching valve 23 returns to position A.

[0030] FIG. 4 is a hardware configuration diagram of the dump truck 1. The dump truck 1 includes a controller 30. The controller 30 includes a CPU (Central Processing Unit) 31 and a memory 32. The memory 32 is configured, for example, with a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The controller 30 realizes the processing described below by having the CPU read and execute program code stored in the ROM or HDD. The RAM is used as a work area when the CPU executes a program.

[0031] However, the specific configuration of the controller 30 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0032] The controller 30 controls the engine 11, the main generator 12, the inverters 14L and 14R, the chopper 16, the charge / discharge controller 18, the regulator 22a, and the directional switching valve 23 based on an operation signal output from the operating device 6a, a rotation speed signal output from the rotation speed sensor 11a, and a remaining amount signal output from the remaining amount sensor 19a.

[0033] In response to depression of the accelerator pedal, the controller 30 increases the rotation speed of the engine 11, outputs power from the main generator 12 or the storage battery 19 to the inverters 14L, 14R, and controls the inverters 14L, 14R to increase the rotation speed of the traction motors 15L, 15R. Details of this control will be described later with reference to FIG. 6.

[0034] In response to depression of the brake pedal, the controller 30 reduces the rotation speed of the engine 11 and operates the traveling motors 15L, 15R as electric brakes. Furthermore, when braking the dump truck 1, the controller 30 charges the electric power generated by the traveling motors 15L, 15R into the storage battery 19 via the charge / discharge controller 18, and further causes the surplus electric power to be consumed by the grid box 17 via the chopper 16.

[0035] In addition, in response to operation of the hoist lever, the controller 30 controls the engine 11, the regulator 22a, and the directional switching valve 23 to raise or lower the bed 5 relative to the body frame 2. In addition, while the bed 5 is being raised, the controller 30 stores the electric power generated by the main generator 12 in the storage battery 19 via the charge / discharge controller 18.

[0036] 5 is a flowchart of the charge / discharge control process. The controller 30 repeatedly executes the charge / discharge control process shown in FIG. 5 at predetermined time intervals, for example, while the engine 11 is running.

[0037] First, the controller 30 determines the positions of the travel lever and the hoist lever based on the operation signal output from the operation device 6a (S11, S12). Then, if the travel lever is in the neutral position and the hoist lever is in the upright position (S11: Yes & S12: Yes), the controller 30 increases the engine 11 to a predetermined rotation speed (for example, full rotation), controls the regulator 22a to set the hydraulic pump 22 to a predetermined discharge capacity, and applies a control voltage to the electrode 23a of the directional control valve 23.

[0038] This causes the hoist cylinders 7L, 7R to extend, and the bed 5 begins to rise. Then, while hydraulic oil for raising the bed 5 is being supplied to the hoist cylinders 7L, 7R, the controller 30 executes the processes of steps S13 to S16. Based on the rotation speed signal output from the rotation speed sensor 11a, the controller 30 compares the rotation speed R of the engine 11 with a threshold rotation speed Rth (S13). Furthermore, based on the remaining amount signal output from the remaining amount sensor 19a, the controller 30 compares the remaining battery amount Q of the storage battery 19 with a first threshold remaining amount Qth1 (threshold power) (S14).

[0039] The threshold rotation speed Rth is set, for example, to a rotation speed of the engine 11 that leaves sufficient excess driving force even after subtracting the driving force for rotating the hydraulic pump 22. The first threshold remaining amount Qth1 is set, for example, to a value that ensures sufficient free capacity to store the electric power generated by the main generator 12 until the raising of the loading platform 5 is completed.

[0040] Then, if the rotation speed R of the engine 11 is equal to or greater than the threshold rotation speed Rth and the remaining battery capacity Q is less than the first threshold remaining capacity Qth1 (S13: Yes & S14: Yes), the controller 30 drives the main generator 12 and stores the electric power generated by the main generator 12 in the storage battery 19 via the charge / discharge controller 18 (S15). On the other hand, if the rotation speed R of the engine 11 is less than the threshold rotation speed Rth or the remaining battery capacity Q is equal to or greater than the first threshold remaining capacity Qth1 (S13: No / S14: No), the controller 30 stops the main generator 12 and the charge / discharge controller 18 (S16).

[0041] If the controller 30 determines that the travel lever is in the neutral position and the hoist lever is not in the upright position (S11: Yes & S12: No), the controller 30 waits until the operating device 6a is operated (S17).If the controller 30 determines that the travel lever is in the forward or reverse position (S11: No), the controller 30 executes normal travel processing (S18).

[0042] 6 is a flowchart of the normal driving process. The controller 30 determines whether the brake pedal or the accelerator pedal is depressed based on the operation signal output from the operation device 6a (S21, S22). The controller 30 also compares the remaining battery capacity Q with the first threshold remaining capacity Qth1 or the second threshold remaining capacity Qth2 based on the remaining capacity signal output from the remaining capacity sensor 19a (S23, S24). The second threshold remaining capacity Qth2 may be the same value as the first threshold remaining capacity Qth1, or may be a different value. The second threshold remaining capacity Qth2 is set to, for example, a value greater than the first threshold remaining capacity Qth1.

[0043] Then, when the controller 30 determines that the brake pedal is depressed (i.e., the traveling motors 15L, 15R are generating regenerative power) and the remaining battery power Q is less than the first threshold remaining power Qth1 (S21: Yes & S23: Yes), the controller 30 charges the regenerative power generated by the traveling motors 15L, 15R to the storage battery 19 via the charge / discharge controller 18 (S25). On the other hand, when the controller 30 determines that the brake pedal is depressed and the remaining battery power Q is equal to or greater than the first threshold remaining power Qth1 (S21: Yes & S23: No), the controller 30 stops charging / discharging by the charge / discharge controller 18 (S26).

[0044] Furthermore, if the controller 30 determines that the brake pedal is not depressed and the accelerator pedal is depressed (i.e., the main generator 12 is generating electricity) (S21: No & S22: Yes), and furthermore, if the remaining battery charge Q is equal to or greater than the second threshold remaining charge Qth2 (S24: Yes), the controller 30 outputs the power stored in the storage battery 19 to the inverters 14L, 14R via the charge / discharge controller 18 (S27). As a result, the traction motors 15L, 15R rotate using the power supplied from both the main generator 12 and the storage battery 19.

[0045] On the other hand, if the controller 30 determines that neither the brake pedal nor the accelerator pedal is depressed (i.e., the main generator 12 is not generating electricity) (S21: No & S22: No), it stops charging / discharging by the charge / discharge controller 18 (S26). Furthermore, if the controller 30 determines that the brake pedal is not depressed and the accelerator pedal is depressed (S21: No & S22: Yes) and furthermore the remaining battery charge Q is less than the second threshold remaining charge Qth2 (S24: No), it also stops charging / discharging by the charge / discharge controller 18 (S26).

[0046] According to this embodiment, the driving force of the engine 11, which is rotated at high speed to raise the loading platform 5, is used to generate electricity in the main generator 12, and the electricity is stored in the storage battery 19. This makes it possible to effectively use the output of the engine 11 during soil release, thereby improving fuel efficiency.

[0047] It should be noted that the processes shown in Figures 5 and 6 can be realized not only by the drive circuit 10 shown in Figure 2. Hereinafter, drive circuits 10A, 10B, 10C, and 10D according to modified examples will be described with reference to Figures 7 to 10. Note that components common to the drive circuit 10 shown in Figure 2 are given the same reference numerals, and detailed description will be omitted, with differences being mainly described.

[0048] [Variation 1] Fig. 7 is a diagram showing a drive circuit 10A according to Modification 1. As shown in Fig. 7, the drive circuit 10A according to Modification 1 differs from the drive circuit 10 shown in Fig. 2 in that it further includes a converter 41, an inverter 42, an auxiliary motor 43, and an auxiliary 44. The converter 41 steps down (converts voltage) the DC power generated by the main generator 12 and converted by the rectifier 13, and outputs the power to the inverter 42. The inverter 42 rotates the auxiliary motor 43 using the DC power output from the converter 41. The auxiliary 44 is, for example, a cooling fan that supplies cooling air to the traction motors 15L, 15R and the grid box 17.

[0049] [Variation 2] Fig. 8 is a diagram showing a drive circuit 10B according to Modification 2. As shown in Fig. 8, the drive circuit 10B according to Modification 2 differs from the drive circuit 10A shown in Fig. 7 in that a charge / discharge controller 18, a storage battery 19, an inverter 42, an accessory motor 43, and an accessory 44 are connected in parallel to the main generator 12 via a rectifier 13 and a converter 41. In addition, the converter 41 according to Modification 2 boosts (voltage converts) the power discharged from the storage battery 19 via the charge / discharge controller 18 and outputs the power to the inverters 14L and 14R.

[0050] In step S15 of FIG. 5 , the controller 30 according to the second modification stores the electric power generated by the main generator 12, converted into DC power by the rectifier 13, and stepped down by the converter 41 in the storage battery 19 via the charge / discharge controller 18. The controller 30 according to the second modification may also output the electric power stored in the storage battery 19 to the inverter 42. As a result, the auxiliary motor 43 is driven by the three-phase AC power discharged from the storage battery 19 and converted by the inverter 42. The controller 30 according to the second modification may also output the electric power stored in the storage battery 19 to the inverters 14L, 14R via the converter 41. As a result, the traction motors 15L, 15R are driven by the three-phase AC power discharged from the storage battery 19, boosted by the converter 41, and converted by the inverters 14L, 14R.

[0051] [Variation 3] 9 is a diagram showing a drive circuit 10C according to Modification 3. As shown in FIG. 9, the drive circuit 10C according to Modification 3 differs from the drive circuit 10B shown in FIG. 8 in that it further includes an auxiliary generator 45 and a rectifier 46 and does not include the converter 41. The auxiliary generator 45 is connected to the output shaft of the engine 11. The auxiliary generator 45 generates electric power mainly for driving the auxiliary equipment 44 using the driving force of the engine 11. The rectifier 46 converts the three-phase AC power generated by the auxiliary generator 45 into DC power and outputs it to the charge / discharge controller 18 and the inverter 42.

[0052] 5 , the controller 30 according to the third modification stores the electric power generated by the auxiliary generator 45 in the storage battery 19 via the charge / discharge controller 18. Furthermore, when operating the auxiliary machine 44, the controller 30 according to the third modification may output the electric power generated by the auxiliary generator 45 to the inverter 42, or may output the electric power stored in the storage battery 19 to the inverter 42 via the charge / discharge controller 18.

[0053] [Variation 4] Fig. 10 is a diagram showing a drive circuit 10D according to Modification 4. As shown in Fig. 10, the drive circuit 10D according to Modification 4 differs from the drive circuit 10C shown in Fig. 9 in that it includes a converter 41. The charge / discharge controller 18, the storage battery 19, the inverter 42, the auxiliary motor 43, and the auxiliary equipment 44 are connected in parallel to the main generator 12 via the rectifier 13 and the converter 41, and are also connected in parallel to the auxiliary generator 45 via a rectifier 46. Furthermore, the controller 30 according to Modification 4 executes the process shown in Fig. 11 instead of the process surrounded by the dashed line in Fig. 5.

[0054] Fig. 11 is a flowchart of processing executed by the controller 30 according to Modification 4 in place of the processing enclosed by the dashed line in Fig. 5. The controller 30 according to Modification 4 determines whether or not to operate the accessories 44 (S31) when the rotation speed R of the engine 11 is equal to or greater than the threshold rotation speed Rth and the remaining battery charge Q is less than the first threshold remaining charge Qth1 (S13: Yes & S14: Yes). Examples of cases in which the accessories 44 are operated include when driving the cooling fans that cool the travel motors 15L, 15R immediately after the dump truck 1 has stopped, and when driving the cooling fans that cool the grid box 17 immediately after regenerative power has been consumed by the grid box 17.

[0055] When the controller 30 according to the fourth modification operates the auxiliary machine 44 (S31: Yes), the controller 30 causes the power generated by the main generator 12 to be stored in the storage battery 19 via the charge / discharge controller 18, and supplies the power generated by the auxiliary generator 45 to the auxiliary motor 43 (i.e., operates the auxiliary machine 44) (S32). When the controller 30 according to the fourth modification does not operate the auxiliary machine 44 (S31: No), the controller 30 causes the power generated by the auxiliary generator 45 to be stored in the storage battery 19 via the charge / discharge controller 18 (S33). When the rotation speed R of the engine 11 is lower than the threshold rotation speed Rth or the remaining battery charge Q is equal to or higher than the first threshold remaining charge Qth1 (S13: No / S14: No), the controller 30 according to the fourth modification stops the main generator 12, the charge / discharge controller 18, and the auxiliary generator 45 (S34).

[0056] The above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the present invention. [Explanation of symbols]

[0057] 1 dump truck 2 Body frame 3L, 3R front tires 4L, 4R rear tires 5 Cargo bed 6 Cab 6a Operating device 7L, 7R hoist cylinder 8 hinge pins 9 Decks 10, 10A, 10B, 10C, 10D drive circuit 11 Engine 11a RPM sensor 12 Main generator 13 Rectifier 14L, 14R, 42 inverter 15L, 15R traction motor 16 Chopper 17 Grid Box 18 Charge / Discharge Controller 19 Storage battery 19a Remaining amount sensor 20 Hydraulic circuit 21 Hydraulic oil tank 22 Hydraulic pump 22a regulator 23 Directional valve 23a,23b electrode 30 Controllers 32 memory 41 Converter 43 Auxiliary motor 44 Auxiliary Machinery 45 Auxiliary generator 46 Rectifier

Claims

1. A vehicle body that moves by rotating tires, a loading platform supported on the vehicle body so as to be able to rise and fall; An engine that generates driving force; a main generator that generates electricity using the driving force of the engine; a hydraulic pump that outputs hydraulic oil using the driving force of the engine; a traction motor that rotates the tires using the electric power generated by the main generator; a hoist cylinder that raises and lowers the platform relative to the vehicle body by hydraulic oil output from the hydraulic pump; A storage battery that stores electricity In a dump truck equipped with The system further includes a controller that stores the power generated by the main generator in the storage battery when the power stored in the storage battery while hydraulic oil for raising the loading platform is being supplied to the hoist cylinder is less than a threshold power set to a value that ensures an available capacity for storing the power generated by the main generator until the raising of the loading platform is completed, and that stops the main generator when the power stored in the storage battery is equal to or greater than the threshold power while hydraulic oil for raising the loading platform is being supplied to the hoist cylinder. A dump truck characterized by:

2. The dump truck according to claim 1, Equipped with electric power-driven auxiliary equipment, the storage battery is connected to the main generator in parallel with the auxiliary machinery via a converter that converts the voltage of the electric power generated by the main generator; The controller When the electric power stored in the storage battery is less than the threshold electric power while hydraulic oil for raising the loading platform is being supplied to the hoist cylinder, the electric power generated by the main generator and stepped down by the converter is stored in the storage battery; The auxiliary equipment is driven by the electric power stored in the storage battery. A dump truck characterized by:

3. The dump truck according to claim 2, an auxiliary generator that generates electric power to be supplied to the auxiliary machine; The controller When the power stored in the storage battery is less than the threshold power while hydraulic oil for raising the loading platform is being supplied to the hoist cylinder, When operating the auxiliary equipment, the electric power generated by the main generator is stored in the storage battery, and the auxiliary equipment is operated using the electric power generated by the auxiliary generator. When the auxiliary machine is not operated, the electric power generated by the auxiliary generator is stored in the storage battery. A dump truck characterized by:

4. The dump truck according to claim 1, The controller While hydraulic oil for raising the loading platform is being supplied to the hoist cylinder, if the engine speed is equal to or higher than a threshold speed and the power stored in the storage battery is less than the threshold power, the power generated by the main generator is stored in the storage battery. A dump truck characterized by:

Images