JP7767218B2 - Electrically powered vehicles - Google Patents

Description

The present invention relates to electrically driven vehicles such as dump trucks.

Dump trucks are electrically driven vehicles that are based on a four-wheeled body, with the driver's cab and control box located at the upper front of the body frame, the power unit consisting of an engine, generator, and hydraulic pump located at the lower front of the body frame, and a rear axle consisting of a travel motor and reduction gear at the lower rear of the body frame. They also have a loading platform that can be raised and lowered by a hydraulic cylinder from the center to the rear of the upper body frame, and are used to transport large quantities of crushed stone, soil, or other materials.

To load a dump truck's bed, a large amount of transported materials is loaded into the loading section using a dumping machine (e.g., a hydraulic excavator). After the dump truck has transported the materials to its destination and is driving away, the hydraulic cylinder is extended, causing the bed to rise and fall around the hinge pin as the center of rotation, releasing the materials and completing the transport. The truck then returns to the loading area and repeats the process.

The dump truck described above runs by generating electricity using the engine in the main generator, which is then sent to an electric motor in the rear axle via an inverter and controller to drive the electric motor, which then rotates the tires via a reduction gear, allowing the truck to move. Furthermore, when slowing down or stopping, a means of deceleration using regenerative braking by the electric motor (electric brakes) is used. The regenerative power generated here is passed through the heating resistor of the heat-generating brake resistor device and converted into heat, which is then radiated to the outside by a fan.

In addition, the generator and traction motor generate heat when in operation and therefore need to be cooled, and a cooling system is installed. The cooling system is mainly air-cooled, with a cooling blower driven by an electric motor to blow cooling air. The driving power is generated by an auxiliary generator separate from the main generator, and the auxiliary electric motor is driven and controlled by an inverter and controller so that the object to be cooled is kept below a specified temperature.

Prior art documents disclosing dump truck technology include, for example, Patent Documents 1 and 2. The hybrid dump truck described in Patent Document 1 stores generated electricity or regenerated electricity during deceleration in a storage battery, and discharges the electricity during acceleration to drive the electric motor and travel.

Furthermore, when the hybrid vehicle described in Patent Document 2 is traveling downhill on a slope where no driving force is required, and charges the storage battery with regenerative power generated during electric braking in auto-cruise mode, the regenerative power is used to drive an electric pump (auxiliary equipment) and consume the regenerative power before the storage battery's charge capacity overflows.

Japanese Patent Application Laid-Open No. 2000-299901 Japanese Patent Application Laid-Open No. 2017-30595

As mentioned above, dump trucks, which are electrically driven vehicles, operate to transport loads by accelerating, driving, decelerating, stopping, etc. using the driving and braking of a travel motor, but it is desirable to operate dump trucks while reducing fuel consumption. To achieve this, effective use of the energy in the vehicle drive system is required. Here, as in Patent Documents 1 and 2, it is possible to reduce fuel consumption by installing a storage battery, charging the battery with regenerative power generated during electric braking, and using this charged power to drive the motor through battery charge and discharge control. However, installing a storage battery reduces the load capacity of the transported object by the mass of the storage battery, thereby reducing transport efficiency.

To maintain the load capacity of the transported object, it is necessary to have no or a small number of storage batteries. However, needless to say, if a storage battery is not installed, it is not possible to store regenerative power during electric braking, and the fuel consumption reduction effect cannot be achieved. Alternatively, if the storage battery is small, only a small amount of regenerative power can be stored, and some of the charging and discharging energy is converted into heat due to charging and discharging losses in the storage battery, so fuel consumption reduction is limited.

On the other hand, there is a method in which the regenerative power generated during electric braking is not stored in a battery, but is instead used directly to power other auxiliary machinery. This is energy efficient as there is no charge/discharge loss associated with using a battery, but the effect of reducing fuel consumption is limited as the electric braking time is limited.

In summary, to solve the issue of reducing fuel consumption in electrically driven dump trucks, it is necessary to increase opportunities to generate regenerative power and immediately use it as auxiliary power, rather than prioritizing storing the regenerative power generated during electric braking in a large-capacity storage battery.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide an electrically driven vehicle that can reduce fuel consumption by increasing the opportunities for the traction motor to generate regenerative power.

In order to achieve the above object, the present invention provides a vehicle powertrain comprising an engine, a main generator and an auxiliary generator driven by the engine, a main rectifier that converts power generated by the main generator into DC power, an auxiliary rectifier that converts power generated by the auxiliary generator into DC power, a main circuit to which DC power is supplied from the main rectifier, an auxiliary circuit to which DC power is supplied from the auxiliary rectifier, a travel motor, a travel inverter that converts DC power of the main circuit into AC power and supplies the AC power to the travel motor, an auxiliary motor, an auxiliary inverter that converts DC power of the auxiliary circuit into AC power and supplies the AC power to the auxiliary motor, a converter that reduces the DC power of the main circuit and supplies it to the auxiliary circuit, an accelerator pedal that instructs the travel motor to increase speed, and a brake pedal that instructs the travel motor to decelerate. The electrically driven vehicle is equipped with a controller that controls the auxiliary generator, the traction inverter, the auxiliary equipment inverter, and the converter, and the controller controls the traction inverter so that the traction motor generates regenerative power when the brake pedal is operated.The controller is equipped with a vehicle speed sensor that detects vehicle speed, and the controller detects a state in which neither the accelerator pedal nor the brake pedal is operated and the vehicle speed is equal to or greater than a predetermined threshold as a coasting state.When the controller detects the coasting state, it controls the traction inverter so that the traction motor generates regenerative power, operates the converter, supplies the regenerative power to the auxiliary equipment inverter , and calculates the drive power of the auxiliary equipment motor and controls the traction inverter so that the regenerative power matches the drive power .

With the present invention configured as described above, regenerative power is generated by the traction motor not only when the brake pedal is operated, but also when the vehicle is coasting with neither the accelerator pedal nor the brake pedal operated, and this regenerative power can be used to provide at least a portion of the drive power for the auxiliary motor. As a result, power generation by the auxiliary generator is suppressed, reducing the load on the engine and enabling improved fuel economy.

An electrically driven vehicle according to the present invention can reduce fuel consumption by increasing the opportunities for the traction motor to generate regenerative power.

1 is a schematic diagram of a dump truck according to a first embodiment of the present invention; 1 is a diagram showing the configuration of an electric drive system according to a first embodiment of the present invention; 1 is a control flow diagram of an electric drive system according to a first embodiment of the present invention; 1 is a block diagram of an electric drive system according to a second embodiment of the present invention; 1 is a control flow diagram of an electric drive system according to a second embodiment of the present invention; 1 is a block diagram of an electric drive system according to a third embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a third embodiment of the present invention. 10 is a block diagram of an electric drive system according to a fourth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a fourth embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to a fifth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a fifth embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to a sixth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a sixth embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to a seventh embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a seventh embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to an eighth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to an eighth embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to a ninth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a ninth embodiment of the present invention. 10 is a diagram showing the configuration of an electric drive system according to a tenth embodiment of the present invention; 10 is a control flow diagram of an electric drive system according to a tenth embodiment of the present invention. 11 is a block diagram of an electric drive system according to an eleventh embodiment of the present invention. 11 is a control flow diagram of an electric drive system according to an eleventh embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. Note that in each drawing, equivalent elements are given the same reference numerals, and duplicate explanations will be omitted where appropriate. In this embodiment, the electrically driven vehicle of the present invention is applied to a dump truck, but the application of the present invention is not limited to this.

Figure 1 is a side view of a dump truck according to a first embodiment of the present invention. As shown in Figure 1, the dump truck comprises a body frame 1 and a bed 3 on which a load 2, such as soil or sand, is placed. The body frame 1 and the bed 3 are connected by a hoist cylinder 4 and a hinge pin 5. By extending and retracting the hoist cylinder 4, the bed 3 rotates vertically relative to the body frame 1, with the hinge pin 5 as a fulcrum, allowing the load 2 to be dumped.

The left and right front wheels 6L, 6R, the left and right rear wheels 7L, 7R, a hydraulic oil tank (not shown), etc. are attached to the body frame 1 via mechanical components (not shown). The rotating shafts of the rear wheels 7L, 7R house traction motors 35, 36 (shown in Figure 2) that drive the rear wheels 7L, 7R, and a reducer that adjusts the rotation speed of the rear wheels 7L, 7R.

The dump truck also has a pair of front wheel suspension cylinders 9L, 9R on the front side of the body frame 1, and a pair of rear wheel suspension cylinders 10L, 10R on the rear side of the body frame 1. The front wheel suspension cylinders 9L, 9R are independent suspension cylinders that can raise and lower the left and right front wheels 6L, 6R independently. Their upper ends are attached to the body frame 1, and their lower ends are attached to wheel support members (not shown) that support the left and right front wheels 6L, 6R. The rear wheel suspension cylinders 10L, 10R are independent suspension cylinders that can raise and lower the left and right rear wheels 7L, 7R independently. Their upper ends are attached to the body frame 1, and their lower ends are attached to wheel support members (not shown) that support the left and right rear wheels 7L, 7R.

A deck 11 on which the operator can walk is attached to the front of the body frame 1. Mounted on the top surface of the deck 11 are a cab 12 on which the operator rides to operate the dump truck, a control cabinet 13 housing various power equipment, and a grid box 14 for dissipating excess energy from the control cabinet 13 as heat. Also mounted in the area hidden by the front wheels 6L, 6R is a power unit 15 consisting of a main generator 30, an auxiliary generator 40 (both shown in Figure 2), a main pump (not shown) as a hydraulic power source for hydraulic equipment, and the like.

Figure 2 is a configuration diagram of the electric drive system in this embodiment. In Figure 2, the electric drive system includes an engine 20, a main generator 30, a main rectifier 31, a main circuit 32, traction inverters 33 and 34, traction motors 35 and 36, a chopper 37, a thermal resistor 38, an auxiliary generator 40, an auxiliary rectifier 41, an auxiliary circuit 42, auxiliary inverters 43-46, auxiliary motors 47-50, a converter 60, an accelerator pedal 70, a brake pedal 71, a vehicle speed sensor 72, and a controller 100.

The main generator 30 and auxiliary generator 40 are driven by the engine 20. The main rectifier 31 converts the power generated by the main generator 30 into DC power and supplies it to the main circuit 32. The auxiliary rectifier 41 converts the power generated by the auxiliary generator 40 into DC power and supplies it to the auxiliary circuit 42. The power and voltage of the main circuit 32 and the auxiliary circuit 42 are significantly different, with the main circuit 32 having higher power and voltage.

The traction inverters 33, 34 convert DC power from the main circuit 32 to AC power and supply it to the traction motors 35, 36. The traction motors 35, 36 drive the rear wheels 7L, 7R via a reduction gear (not shown). Operating the traction motors 35, 36 as generators also applies electric braking force to the rear wheels 7L, 7R, slowing the vehicle. The regenerative power generated by the traction motors 35, 36 is converted to DC power by the traction inverters 33, 34 and supplied to the main circuit 32. Most of the regenerative power supplied to the main circuit 32 is supplied to a thermal resistor 38 via a chopper 37, where it is converted into heat. The remaining regenerative power is supplied to the auxiliary circuit 42 via a converter 60. The regenerative power supplied to the auxiliary circuit 42 is converted to AC power by the auxiliary inverters 43-46 and supplied to the auxiliary motors 47-50. At this time, at least a portion of the drive power Q of the auxiliary motors 47-50 is provided by regenerative power, so the load on the engine 20 can be reduced by reducing or stopping the power generation of the auxiliary generator 40.

The auxiliary inverters 43-46 convert the DC power from the auxiliary circuit 42 into AC power and supply it to the auxiliary motors 47-50. The auxiliary motors 47-50 drive auxiliary devices such as cooling fans 80-83. The converter 60 is a step-down device that reduces the DC power from the main circuit 32 and supplies it to the auxiliary circuit 42. The controller 100 controls the engine 20, main generator 30, auxiliary generator 40, traction inverters 33, 34, auxiliary inverters 43-46, and converter 60 in response to input signals from the accelerator pedal 70, brake pedal 71, and vehicle speed sensor 72.

The controller 100 has a coasting detection unit 101 that detects the coasting state of the dump truck. The coasting detection unit 101 is a functional block realized when a computing device such as a CPU executes a program stored in a storage device such as a ROM or RAM.

Figure 3 is a control flow diagram for the electric drive system in this embodiment. The processing of each step will be explained in order below.

The controller 100 first determines whether the brake pedal 71 is being operated (step S101). If the determination in step S101 is No, the controller controls the traction inverters 33, 34 to generate regenerative power corresponding to the amount of brake pedal 71 operation, turns on the chopper 37, and turns on the converter 60 (step S102), and then ends the flow. As a result, electric braking force corresponding to the amount of brake pedal 71 operation is generated in the traction motors 35, 36, decelerating the vehicle body. Furthermore, most of the regenerative power of the traction motors 35, 36 is consumed by the thermal resistor 38, and the remaining regenerative power is stepped down by the converter 60 and then used to drive the accessory motors 47-50.

If step S101 returns Yes, it is determined whether the accelerator pedal 70 is being operated (step S103). If step S103 returns No, the driving inverters 33, 34 are controlled so that power corresponding to the amount of operation of the accelerator pedal 70 is supplied to the driving motors 35, 36, the converter 60 is turned OFF (step S104), and the flow ends. This causes the vehicle body to accelerate according to the amount of operation of the accelerator pedal 70.

If the answer to step S103 is Yes, it is determined whether the vehicle speed is equal to or greater than a predetermined threshold value F (step S105). If the answer to step S105 is No, the process proceeds to step S104.

If the answer in step S105 is Yes, the driving inverters 33, 34 are controlled to generate regenerative power, the converter 60 is turned ON (step S106), and the flow ends. The regenerative power referred to here is, for example, regenerative power generated in response to an electric braking force that does not affect coasting, and does not have to be constant. As a result, at least a portion of the drive power Q of the auxiliary motors 47-50 during coasting is provided by regenerative power, so power generation by the auxiliary generator 40 can be stopped or suppressed.

(summary)
In this embodiment, the system includes an engine 20, a main generator 30 and an auxiliary generator 40 driven by the engine 20, a main rectifier 31 that converts the power generated by the main generator 30 into DC power, an auxiliary rectifier 41 that converts the power generated by the auxiliary generator 40 into DC power, a main circuit 32 to which DC power is supplied from the main rectifier 31, an auxiliary circuit 42 to which DC power is supplied from the auxiliary rectifier 41, travel motors 35 and 36, and a power converter 44 that converts the DC power of the main circuit 32 into AC power. The inverters 33, 34 supply power to the drive motors 35, 36; the inverters 43, 46 convert DC power from the auxiliary circuit 42 into AC power and supply it to the auxiliary motors 47, 50; the converter 60 reduces the DC power from the main circuit 32 and supplies it to the auxiliary circuit 42; the accelerator pedal 70 commands the drive motors 35, 36 to increase speed; the brake pedal 71 commands the drive motors 35, 36 to decrease speed; and a controller 100 that controls the main generator 30, the auxiliary generator 40, the traction inverters 33, 34, the auxiliary inverters 43 to 46, and the converter 60 in response to input signals from the controller 100. The controller 100 controls the traction inverters 33, 34 so that the traction motors 35, 36 generate regenerative power when the brake pedal 71 is operated. The controller 100 is provided with a vehicle speed sensor 72 that detects vehicle speed, and detects a state in which neither the accelerator pedal 70 nor the brake pedal 71 is operated and the vehicle speed is equal to or greater than a predetermined threshold value F as a coasting state. When the controller 100 detects the coasting state, it controls the traction inverters 33, 34 so that the traction motors 35, 36 generate regenerative power, operates the converter 60, and controls the auxiliary inverters 43 to 46 so that the regenerative power is supplied to the auxiliary motors 47 to 50.

With this embodiment configured as described above, regenerative power is generated by the traction motors 35, 36 when the brake pedal 71 is operated, as well as when the vehicle is coasting with neither the accelerator pedal 70 nor the brake pedal 71 operated, and this regenerative power can cover at least a portion of the drive power Q of the accessory motors 47-50. As a result, power generation by the auxiliary generator 40 is suppressed, reducing the load on the engine 20 and enabling improved fuel economy.

The regenerative power generated during coasting is equivalent to the drive power (several tens of kW) of the auxiliary motors 47-50, and is much smaller than the regenerative power (several thousand kW) generated when the brake pedal 71 is depressed, so it has almost no effect on driving operation. Furthermore, by supplying regenerative power directly to the auxiliary motors 47-50, the capacity of the storage battery used to store the regenerative power can be reduced. This ensures the dump truck's load capacity, allowing productivity to be maintained without reducing transport efficiency.

A second embodiment of the present invention will be described, focusing on the differences from the first embodiment. Figure 4 is a configuration diagram of the electric drive system in this embodiment. In Figure 4, the controller 100 further includes an auxiliary power calculation unit 102 that calculates the drive power Q of the auxiliary motors 47-50. The drive power Q is calculated by integrating the output power of the auxiliary inverters 43-46. Note that because the drive power Q is approximately equal to the power generated by the auxiliary generator 40, the power generated by the auxiliary generator 40 may be calculated as the drive power Q.

Figure 5 is a control flow diagram of the electric drive system in this embodiment. In Figure 5, the processing of steps S201 to S205 is the same as steps S101 to S105 (shown in Figure 3) in the first embodiment.

If it is determined in step S205 that the vehicle speed is equal to or greater than threshold value F (Yes), the drive power Q of the accessory motors 47-50 is calculated, the traction inverters 33, 34 are controlled to generate regenerative power equivalent to drive power Q, the converter 60 is turned ON (step S206), and the flow ends. As a result, the drive power Q of the accessory motors 47-50 is supplied solely by regenerative power during coasting, and power generation by the auxiliary generator 40 can be stopped.

(summary)
In this embodiment, when the controller 100 detects a coasting state, it calculates the drive power Q of the auxiliary motors 47 to 50 and controls the drive inverters 33, 34 so that the regenerative power obtained from the travel motors 35, 36 matches the drive power Q.

In this embodiment configured as described above, the drive power Q of the auxiliary motors 47-50 can be supplied solely by regenerative power during coasting, thereby stopping the power generation of the auxiliary generator 40 and improving the fuel efficiency of the engine 20 compared to the first embodiment.

A third embodiment of the present invention will be described, focusing on the differences from the second embodiment. Figure 6 is a configuration diagram of the electric drive system in this embodiment. In Figure 6, the electric drive system further includes a suspension pressure sensor 73 that detects the pressure in the front wheel suspension cylinders 9L, 9R and the rear wheel suspension cylinders 10L, 10R, and the controller 100 further includes a descending inclination angle calculation unit 103 that calculates the descending inclination angle θ of the driving surface.

Figure 7 is a control flow diagram of the electric drive system in this embodiment. In Figure 6, the processing of steps S301 to S305 is the same as steps S201 to S205 (shown in Figure 5) in the second embodiment.

If it is determined in step S305 that the vehicle speed is greater than or equal to threshold value F (Yes), it is determined whether the descending inclination angle θ is greater than or equal to a predetermined threshold value α (e.g., 3°) (step S306). The descending inclination angle θ is calculated using the following formula:

Here, the front wheel load Wf is calculated from the pressure in the front wheel suspension cylinders 9L, 9R, and the front wheel load Wf is calculated from the pressure in the rear wheel suspension cylinders 10L, 10R.

If the result of step S306 is No, the process of step S304 is executed and the flow ends. As a result, no regenerative power is generated when coasting except on a downhill slope.

If the answer in step S306 is Yes, the drive power Q of the accessory motors 47-50 is calculated, the traction inverters 33, 34 are controlled to generate regenerative power equivalent to the drive power Q, the converter 60 is turned ON (step S307), and the flow ends. As a result, when coasting downhill, the drive power Q of the accessory motors 47-50 is covered solely by the regenerative power of the traction motors 35, 36, so power generation by the auxiliary generator 40 can be stopped.

(summary)
The electrically driven vehicle in this embodiment is equipped with a sensor (suspension pressure sensor 73) for detecting the downward slope angle θ of the driving surface, and when the controller 100 detects a coasting state and the downward slope angle θ is less than a predetermined threshold value α, it controls the driving inverters 33, 34 so that no regenerative power is generated, and does not operate the converter 60.

With this embodiment configured as described above, when coasting on slopes other than downhill (where deceleration due to running resistance is large), no regenerative power is generated and the running motors 35, 36 do not generate braking force, preventing any impact on running operation. In this embodiment, the downhill inclination angle θ is calculated using the output of the suspension pressure sensor 73, but it may also be calculated using the output of an inclination sensor mounted on the vehicle body.

A fourth embodiment of the present invention will be described, focusing on the differences from the third embodiment. Figure 8 is a configuration diagram of the electric drive system in this embodiment. In Figure 8, the controller 100 has a load amount calculation unit 104 that calculates the load amount W on the loading platform 3, instead of the descent inclination angle calculation unit 103 (shown in Figure 6).

Figure 9 is a control flow diagram of the electric drive system in this embodiment. In Figure 7, the processing of steps S401 to S405 is the same as steps S301 to S305 (shown in Figure 7) in the third embodiment.

If it is determined in step S405 that the vehicle speed is equal to or greater than threshold value F (Yes), it is then determined whether the load weight W on the loading platform 3 is equal to or greater than a predetermined threshold value M (e.g., 100 tons) (step S406). The load weight W is calculated by subtracting the total of the front wheel load Wf, calculated from the pressure in the front wheel suspension cylinders 9L, 9R, and the rear wheel load Wr, calculated from the pressure in the rear wheel suspension cylinders 10L, 10R, from the total of the front wheel load Wf and rear wheel load Wr in an unladen state.

If the result of step S406 is No, the process of step S404 is executed and the flow ends. As a result, no regenerative power is generated when coasting with a large load weight W.

If the answer in step S406 is Yes, the drive power Q of the accessory motors 47-50 is calculated, the traction inverters 33, 34 are controlled to generate regenerative power equivalent to the drive power Q, the converter 60 is turned ON (step S307), and the flow ends. As a result, when coasting with a small load weight W, the drive power Q of the accessory motors 47-50 is covered solely by the regenerative power of the traction motors 35, 36, so power generation by the auxiliary generator 40 can be stopped.

(summary)
The electrically driven vehicle in this embodiment is equipped with a cargo bed 3 and a sensor (suspension pressure sensor 73) for detecting the load amount on the cargo bed 3, and when the controller 100 detects a coasting state and the load amount W is equal to or greater than a predetermined threshold value M, it controls the driving inverters 33, 34 so that no regenerative power is generated, and does not operate the converter 60.

With this embodiment configured as described above, when coasting with a large load weight W (large deceleration due to running resistance), regenerative power is not generated and the running motors 35, 36 do not generate braking force, preventing any impact on running operation. Note that in this embodiment, whether or not to generate regenerative power during coasting is determined based on the load weight W (step S406), but the determination may also be based on the vehicle body mass.

A fifth embodiment of the present invention will be described, focusing on the differences from the second embodiment. Figure 10 is a configuration diagram of the electric drive system in this embodiment. In Figure 10, the controller 100 has a power generation output detection unit 105 that detects the power generation output of the auxiliary generator 40, instead of the auxiliary power calculation unit 102 (shown in Figure 4). The power generation output detection unit 105 detects the power generation operation of the auxiliary generator 40 based on the output of a sensor (for example, a voltage sensor 74 that detects the power generation voltage of the auxiliary generator 40).

Figure 11 is a control flow diagram of the electric drive system in this embodiment. In Figure 11, the processing of steps S501 to S505 is the same as steps S201 to S205 (shown in Figure 5) in the second embodiment.

If it is determined in step S505 that the vehicle speed is equal to or greater than threshold value F (Yes), it is determined whether the power generation output of the auxiliary generator 40 has been detected (whether the auxiliary generator 40 is generating power) (step S506). If it is determined in step S506 that it is Yes, the traction inverters 33, 34 are controlled so that the regenerative power of the traction motors 35, 36 is slightly increased (step S507), and the process returns to step S506. This allows the regenerative power of the traction motors 35, 36 to match the drive power Q of the auxiliary motors 47-50.

If the answer is No in step S506, the converter 60 is turned ON (step S609) and the flow ends. As a result, the drive power Q of the auxiliary motors 47-50 is provided solely by the regenerative power of the traction motors 35, 36 during coasting, so power generation by the auxiliary generator 40 can be stopped.

(summary)
The electrically driven vehicle in this embodiment is equipped with a sensor (voltage sensor 74) for detecting the power generation output of the auxiliary generator, and when the controller 100 detects a coasting state, it controls the traction inverters 33, 34 so that the regenerative power of the traction motors 35, 36 increases until the power generation output of the auxiliary generator 40 is no longer detected.

With this embodiment configured as described above, power generation by the auxiliary generator 40 can be stopped during coasting by increasing the regenerative power of the travel motors 35, 36 until the auxiliary generator 40 stops generating power.

The sixth embodiment of the present invention will be described, focusing on the differences from the fifth embodiment. Figure 12 is a configuration diagram of the electric drive system in this embodiment. In Figure 12, the electric drive system further includes a suspension pressure sensor 73, and the controller 100 further includes a descending inclination angle calculation unit 103.

Figure 13 is a control flow diagram of the electric drive system in this embodiment. In Figure 13, the processing of steps S601 to S605 is the same as steps S501 to S505 (shown in Figure 11) in the fifth embodiment.

If it is determined in step S605 that the vehicle speed is greater than or equal to threshold value F (Yes), it is determined whether the descending gradient angle θ is greater than or equal to threshold value α (step S606). If it is determined in step S606 that the answer is Yes, it is determined whether the power generation output of the auxiliary generator 40 has been detected (whether the auxiliary generator 40 is generating power) (step S607).

If the answer in step S607 is Yes, the driving inverters 33, 34 are controlled so that the regenerative power of the driving motors 35, 36 is slightly increased (step S608), and the process returns to step S607. This allows the regenerative power of the driving motors 35, 36 to match the drive power Q of the accessory motors 47-50.

If step S607 returns No, the converter 60 is turned ON (step S609), and the flow ends. As a result, the drive power Q of the auxiliary motors 47-50 is provided solely by the regenerative power of the traction motors 35, 36 during coasting, so power generation by the auxiliary generator 40 can be stopped.

(summary)
The electrically driven vehicle in this embodiment is equipped with a sensor (voltage sensor 74) for detecting the power generation output of the auxiliary generator 40, and when the controller 100 detects a coasting state and the descending slope angle θ is equal to or greater than a predetermined threshold value α, it controls the traction inverters 33, 34 so that the regenerative power of the traction motors 35, 36 increases until the power generation output of the auxiliary generator 40 is no longer detected.

With this embodiment configured as described above, when coasting downhill, the power generation of the auxiliary generator 40 can be stopped by increasing the regenerative power of the travel motors 35, 36 until the auxiliary generator 40 stops generating power.

The electrically driven vehicle in this embodiment is also equipped with a sensor (suspension pressure sensor 73) for detecting the downward slope angle θ of the driving surface. When the controller 100 detects a coasting state and the downward slope angle θ is less than a predetermined threshold value α, it controls the driving inverters 33, 34 so that regenerative power is not generated, and does not operate the converter 60. As a result, when coasting on a slope other than a downward slope (when deceleration due to running resistance is large), regenerative power is not generated and the driving motors 35, 36 do not generate braking force, preventing any impact on driving operation.

The seventh embodiment of the present invention will be described, focusing on the differences from the fifth embodiment. Figure 14 is a configuration diagram of the electric drive system in this embodiment. In Figure 14, the electric drive system further includes a suspension pressure sensor 73, and the controller 100 further includes a cargo amount calculation unit 104.

Figure 15 is a control flow diagram of the electric drive system in this embodiment. In Figure 15, the processing of steps S701 to S705 is the same as steps S501 to S505 (shown in Figure 11) in the fifth embodiment.

If it is determined in step S705 that the vehicle speed is equal to or greater than threshold value F (Yes), it is determined whether the load weight W is equal to or greater than threshold value M (step S706). If it is determined in step S706 that the answer is Yes, it is determined whether the power generation output of the auxiliary generator 40 has been detected (whether the auxiliary generator 40 is generating power) (step S707).

If the answer in step S707 is Yes, the traction inverters 33, 34 are controlled so that the regenerative power of the traction motors 35, 36 is slightly increased (step S708), and the process returns to step S707. This allows the regenerative power of the traction motors 35, 36 to match the drive power Q of the accessory motors 47-50.

If the answer is No in step S707, the converter 60 is turned ON (step S709) and the flow ends. As a result, the drive power Q of the auxiliary motors 47-50 is provided solely by the regenerative power of the traction motors 35, 36 during coasting, so power generation by the auxiliary generator 40 can be stopped.

(summary)
The electrically driven vehicle in this embodiment is equipped with a sensor (voltage sensor 74) for detecting the power generation output of the auxiliary generator 40, and when the controller 100 detects a coasting state and the load weight W is less than a predetermined threshold value M, it controls the traction inverters 33, 34 so that the regenerative power of the traction motors 35, 36 increases until the power generation output of the auxiliary generator 40 is no longer detected.

With this embodiment configured as described above, when coasting with a small load weight W, the power generation of the auxiliary generator 40 can be stopped by increasing the regenerative power of the travel motors 35, 36 until the auxiliary generator 40 stops generating power.

The electrically driven vehicle in this embodiment also includes a loading platform 3 and a sensor (suspension pressure sensor 73) for detecting the load weight W on the loading platform 3. When the controller 100 detects a coasting state and the load weight W is equal to or greater than a predetermined threshold value M, it controls the travel inverters 33, 34 to prevent regenerative power from being generated and does not operate the converter 60. As a result, when coasting with a large load weight W (large deceleration due to running resistance), no regenerative power is generated and the travel motors 35, 36 do not generate braking force, preventing any impact on running operation.

The eighth embodiment of the present invention will be described, focusing on the differences from the third embodiment. Figure 16 is a configuration diagram of the electric drive system in this embodiment. In Figure 16, the electric drive system further includes a storage battery 90 and a charge/discharge controller 91 consisting of a bidirectional converter. The storage battery 90 is connected to the auxiliary circuit 42 via the charge/discharge controller 91. The charge/discharge controller 91 charges and discharges the storage battery 90 in response to commands from the controller 100.

Figure 17 is a control flow diagram of the electric drive system in this embodiment. In Figure 17, the processing of steps S801 and S803 to S806 is the same as steps S301 and S303 to S306 (shown in Figure 6) in the third embodiment.

If step S801 returns No, the system controls the traction inverters 33, 34 to generate regenerative power according to the amount of brake pedal 71 depression, turns on the chopper 37, turns on the converter 60, and turns on charging of the storage battery 90 (step S802), and then ends the flow. This generates electric braking force according to the amount of brake pedal 71 depression in the traction motors 35, 36, decelerating the vehicle. Furthermore, most of the regenerative power of the traction motors 35, 36 is consumed by the thermal resistor 38, and the remaining regenerative power is stepped down by the converter 60 and then used to drive the accessory motors 47-50 and charge the storage battery 90.

If step S806 determines that the descending gradient angle θ is greater than or equal to the threshold value α (Yes), the process then determines whether the descending gradient angle θ is greater than or equal to the threshold value β (>α) (step S807). If step S807 returns No, the process calculates the drive power Q of the accessory motors 47-50, controls the traction inverters 33, 34 to generate regenerative power equivalent to the drive power Q, turns on the converter 60, and turns off charging of the storage battery 90 (step S808), ending the flow. As a result, when coasting on a slight downhill slope, the drive power Q of the accessory motors 47-50 is provided solely by regenerative power, allowing the power generation of the auxiliary generator 40 to be stopped.

If step S807 returns Yes, the system controls the traction inverters 33, 34 to further increase the regenerative power of the traction motors 35, 36, turns on the converter 60, and turns on charging of the storage battery 90 (step S1111), ending the flow. As a result, when coasting on a steep downhill slope, part of the regenerative power is used to provide the drive power Q of the accessory motors 47-50 and charge the storage battery 90. The power charged to the storage battery 90 is used to drive the accessory motors 47-50 when driving without operating the brake pedal 71. As a result, the power generated by the auxiliary generator 40 is suppressed, reducing the load on the engine 20 that drives the auxiliary generator 40 and improving fuel efficiency.

(summary)
In this embodiment, a sensor (suspension pressure sensor 73) for detecting the descending inclination angle θ of the traveling surface, a storage battery 90, and a charge/discharge controller 91 for supplying and receiving power between the storage battery 90 and the auxiliary circuit 42 are provided. When the controller 100 detects a coasting state and the descending inclination angle θ is equal to or greater than a predetermined first threshold value α and less than a predetermined second threshold value β, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power obtained from the traveling motors 35, 36 matches the drive power Q of the auxiliary motors 47 to 50, and converts the inverters 33, 34 to the converters 34. The inverter 60 is operated, and the auxiliary inverters 43 to 46 and the charge/discharge controller 91 are controlled so that the regenerative power is supplied only to the auxiliary motors 47 to 50. When a coasting state is detected and the descending slope angle θ is equal to or greater than the second threshold value β, the inverters 33, 34 are controlled so that the regenerative power is greater than the drive power Q. The converter 60 is operated, and the auxiliary inverters 43 to 46 and the charge/discharge controller 91 are controlled so that the regenerative power is supplied only to the auxiliary motors 47 to 50 and the storage battery 90.

With this embodiment configured as described above, when coasting on a slight downhill slope (when deceleration due to running resistance is small), the accessory motors 47-50 can be driven solely by regenerative power, and when coasting on a steep downhill slope (when deceleration due to running resistance is very small), the accessory motors 47-50 can be driven solely by regenerative power and the storage battery 90 can be charged.

The ninth embodiment of the present invention will be described below, focusing on the differences from the eighth embodiment. Figure 18 is a configuration diagram of the electric drive system in this embodiment. In Figure 18, the controller 100 has a cargo amount calculation unit 104 instead of the descent tilt angle calculation unit 103 (shown in Figure 16).

Figure 19 is a control flow diagram of the electric drive system in this embodiment. In Figure 19, the processing of steps S901 to S905 is the same as steps S801 to S805 (shown in Figure 17) in the eighth embodiment.

If step S905 determines that the vehicle speed is equal to or greater than threshold F (Yes), the system determines whether the load weight W is less than threshold M (step S906). If step S906 returns No, the system calculates the drive power Q of the accessory motors 47-50, controls the traction inverters 33, 34 to generate regenerative power equivalent to drive power Q, turns on the converter 60, and turns off charging of the storage battery 90 (step S907), ending the flow. As a result, when coasting with a large load weight W, the drive power Q of the accessory motors 47-50 is provided solely by the regenerative power of the traction motors 35, 36, allowing the auxiliary generator 40 to stop generating power.

If step S906 returns Yes, the drive power Q of the accessory motors 47-50 is calculated, the drive inverters 33, 34 are controlled so that the regenerative power of the traction motors 35, 36 is greater than the drive power Q of the accessory motors 47-50, the converter 60 is turned ON, charging of the storage battery 90 is turned ON (step S907), and the flow ends. As a result, when coasting with a small load weight W, part of the regenerative power of the traction motors 35, 36 covers the drive power Q of the accessory motors 47-50, and the remaining regenerative power is charged to the storage battery 90.

(summary)
In this embodiment, the vehicle is equipped with a loading platform 3, a sensor (suspension pressure sensor 73) for detecting the amount of cargo on the loading platform 3, and a storage battery 90 connected to the auxiliary circuit 42. When the controller 100 detects a coasting state and the amount of cargo W on the loading platform 3 is equal to or greater than a predetermined threshold M, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power obtained from the traveling motors 35, 36 matches the drive power Q of the auxiliary motors 47-50, operates the converter 60, and controls the auxiliary inverters 43-46 and the charge/discharge controller 91 so that the regenerative power is supplied only to the auxiliary motors 47-50. When the controller 100 detects a coasting state and the amount of cargo W is less than the threshold M, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power is greater than the drive power Q, operates the converter 60, and controls the auxiliary inverters 43-46 and the charge/discharge controller 91 so that the regenerative power is supplied to the auxiliary motors 47-50 and the storage battery 90.

With this embodiment configured as described above, when coasting with a large load weight W (when deceleration due to running resistance is large), the accessory motors 47-50 are driven solely by regenerative power, and when coasting with a small load weight W (when deceleration due to running resistance is small), the accessory motors 47-50 can be driven solely by regenerative power and the storage battery 90 can be charged.

The tenth embodiment of the present invention will be described below, focusing on the differences from the eighth embodiment. Figure 20 is a configuration diagram of the electric drive system in this embodiment. In Figure 20, the controller 100 has a power generation output detection unit 105 instead of the auxiliary power calculation unit 102 (shown in Figure 16).

Figure 21 is a control flow diagram of the electric drive system in this embodiment. In Figure 21, the processing of steps S1001 to S1006 is the same as steps S801 to S806 (shown in Figure 17) in the eighth embodiment.

If step S1006 determines that the descending inclination angle θ is greater than or equal to the threshold value α (Yes), it is determined whether the power generation output of the auxiliary generator 40 has been detected (whether the auxiliary generator 40 is generating power) (step S1007). If step S1007 determines Yes, the traction inverters 33, 34 are controlled to slightly increase the regenerative power of the traction motors 35, 36 (step S1008), and the process returns to step S1007. This allows the regenerative power of the traction motors 35, 36 to match the drive power Q of the auxiliary motors 47-50.

If step S1007 returns No, it is determined whether the descending slope angle θ is equal to or greater than the threshold value β (step S1009). If step S1009 returns No, the converter 60 is turned ON, charging of the storage battery 90 is turned OFF (step S1010), and the flow ends. As a result, when coasting on a slight descending slope, the regenerative power of the travel motors 35, 36 provides the drive power Q of the auxiliary motors 47-50, allowing power generation by the auxiliary generator 40 to be stopped.

If step S1009 returns Yes, the drive inverters 33, 34 are controlled to further increase the regenerative power of the drive motors 35, 36, the converter 60 is turned ON, charging of the storage battery 90 is turned ON (step S1011), and the flow ends. As a result, during coasting on a steep downhill slope, the regenerative power of the drive motors 35, 36 covers the drive power Q of the accessory motors 47-50, and the remaining regenerative power is charged to the storage battery 90.

(summary)
In this embodiment, a sensor (suspension pressure sensor 73) for detecting the descending inclination angle θ of the traveling surface, a storage battery 90, and a charge/discharge controller 91 for supplying and receiving power between the storage battery 90 and the auxiliary circuit 42 are provided. When the controller 100 detects a coasting state and the descending inclination angle θ is equal to or greater than a predetermined first threshold value α and less than a predetermined second threshold value β, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power obtained from the traveling motors 35, 36 matches the drive power Q of the auxiliary motors 47 to 50, and converts the inverters 33, 34 to the converters 34. The inverter 60 is operated, and the auxiliary inverters 43 to 46 and the charge/discharge controller 91 are controlled so that the regenerative power is supplied only to the auxiliary motors 47 to 50. When a coasting state is detected and the descending slope angle θ is equal to or greater than the second threshold value β, the inverters 33, 34 are controlled so that the regenerative power is greater than the drive power Q. The converter 60 is operated, and the auxiliary inverters 43 to 46 and the charge/discharge controller 91 are controlled so that the regenerative power is supplied only to the auxiliary motors 47 to 50 and the storage battery 90.

With this embodiment configured as described above, when coasting on a slight downhill slope (when deceleration due to running resistance is small), the accessory motors 47-50 can be driven solely by regenerative power, and when coasting on a steep downhill slope (when deceleration due to running resistance is very small), the accessory motors 47-50 can be driven solely by regenerative power and the storage battery 90 can be charged.

The eleventh embodiment of the present invention will be described below, focusing on the differences from the tenth embodiment. Figure 22 is a configuration diagram of the electric drive system in this embodiment. In Figure 22, the controller 100 has a cargo amount calculation unit 104 instead of the descent tilt angle calculation unit 103 (shown in Figure 20).

Figure 23 is a control flow diagram of the electric drive system in this embodiment. In Figure 23, the processing of steps S1101 to S1105 is the same as steps S1001 to S1005 (shown in Figure 21) in the tenth embodiment.

If it is determined in step S1105 that the vehicle speed is equal to or greater than threshold value F (Yes), it is determined whether the power generation output of the auxiliary generator 40 has been detected (whether the auxiliary generator 40 is generating power) (step S1106). If it is determined in step S1106 that it is Yes, the traction inverters 33, 34 are controlled so that the regenerative power of the traction motors 35, 36 is slightly increased (step S1107), and the process returns to step S1106. This allows the regenerative power of the traction motors 35, 36 to match the drive power Q of the auxiliary motors 47-50.

If step S1106 returns No, it is determined whether the load weight W is less than the threshold value M (step S1108). If step S1108 returns No, the converter 60 is turned ON, charging of the storage battery 90 is turned OFF (step S1109), and the flow ends. As a result, when coasting with a large load weight W, the drive power Q of the accessory motors 47-50 is provided solely by regenerative power.

If step S1108 returns Yes, the drive inverters 33, 34 are controlled to further increase the regenerative power of the drive motors 35, 36, the converter 60 is turned ON, charging of the storage battery 90 is turned ON (step S1110), and the flow ends. As a result, when coasting with a small load W, part of the regenerative power is used to cover the drive power Q of the accessory motors 47-50, and the remaining regenerative power is charged to the storage battery 90.

(summary)
In this embodiment, the vehicle is equipped with a loading platform 3, a sensor (suspension pressure sensor 73) for detecting the load weight W of the loading platform 3, and a storage battery 90 connected to the auxiliary circuit 42. When the controller 100 detects a coasting state and the load weight W is equal to or greater than a predetermined threshold value M, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power obtained from the traveling motors 35, 36 matches the drive power Q of the auxiliary motors 47-50, operates the converter 60, and controls the auxiliary inverters 43-46 and the charge/discharge controller 91 so that the regenerative power is supplied only to the auxiliary motors 47-50. When the controller 100 detects a coasting state and the load weight W is less than the threshold value M, the controller 100 controls the traveling inverters 33, 34 so that the regenerative power is greater than the drive power Q, operates the converter 60, and controls the auxiliary inverters 43-46 and the charge/discharge controller 91 so that the regenerative power is supplied only to the auxiliary motors 47-50.

With this embodiment configured as described above, when coasting with a large load weight W (when deceleration due to running resistance is large), the accessory motors 47-50 are driven solely by regenerative power, and when coasting with a small load weight W (when deceleration due to running resistance is small), the accessory motors 47-50 can be driven solely by regenerative power and the storage battery 90 can be charged.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and includes various modifications. 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 those having all of the configurations described. Furthermore, it is possible to add part of the configuration of one embodiment to the configuration of another embodiment, or to delete part of the configuration of one embodiment or replace it with part of another embodiment.

1...body frame, 2...load, 3...bed, 4...hoist cylinder, 5...hinge pin, 6L, 6R...front wheels, 7L, 7R...rear wheels, 9L, 9R...front wheel suspension cylinder, 10L, 10R...rear wheel suspension cylinder, 11...deck, 12...cab, 13...control cabinet, 14...grid box, 15...power unit, 20...engine, 30...main generator, 31...main rectifier, 32...main circuit, 33, 34...travel inverter, 35, 36...travel motor, 37...chopper, 38...thermal resistor Resistor, 40... Auxiliary generator, 41... Auxiliary rectifier, 42... Auxiliary circuit, 43-46... Auxiliary inverter, 47-50... Auxiliary motor, 60... Converter, 70... Accelerator pedal, 71... Brake pedal, 72... Vehicle speed sensor, 73... Suspension pressure sensor, 74... Voltage sensor, 80-83... Cooling fan, 90... Storage battery, 91... Charge/discharge controller, 100... Controller, 101... Coasting detection unit, 102... Auxiliary power calculation unit, 103... Descending gradient angle calculation unit, 104... Load amount calculation unit, 105... Power generation output detection unit.

Claims (6)

The engine and
a main generator and an auxiliary generator driven by the engine;
a main rectifier that converts the power generated by the main generator into DC power;
an auxiliary rectifier that converts the power generated by the auxiliary generator into DC power;
a main circuit supplied with DC power from the main rectifier;
an auxiliary circuit to which DC power is supplied from the auxiliary rectifier;
A traction motor;
a driving inverter that converts DC power of the main circuit into AC power and supplies the AC power to the driving motor;
an accessory motor;
an auxiliary inverter that converts DC power of the auxiliary circuit into AC power and supplies the AC power to the auxiliary motor;
a converter that reduces the DC power of the main circuit and supplies the reduced DC power to the auxiliary circuit;
an accelerator pedal for instructing the travel motor to increase its speed;
a brake pedal for instructing the driving motor to decelerate;
a controller that controls the main generator, the auxiliary generator, the driving inverter, the auxiliary inverter, and the converter in response to input signals from the accelerator pedal and the brake pedal,
In an electrically driven vehicle, the controller controls the traveling inverter so that the traveling motor generates regenerative power when the brake pedal is operated,
Equipped with a vehicle speed sensor that detects vehicle speed,
The controller
a state in which neither the accelerator pedal nor the brake pedal is operated and the vehicle speed is equal to or greater than a predetermined threshold is detected as a coasting state;
When the coasting state is detected, the inverter for driving is controlled so that the driving motor generates regenerative power, the converter is operated, and the regenerative power is supplied to the motor for auxiliary equipment ;
A drive power of the auxiliary motor is calculated, and the traction inverter is controlled so that the regenerative power matches the drive power.
An electrically driven vehicle. 2. The electrically driven vehicle according to claim 1,
a sensor for detecting the power generation output of the auxiliary generator;
When the controller detects the coasting state, the controller controls the traction inverter so that regenerative power of the traction motor increases until power generation output of the auxiliary generator is no longer detected. 2. The electrically driven vehicle according to claim 1,
A sensor is provided for detecting the downward slope angle of the running surface,
the controller, when detecting the coasting state and the descending slope angle being less than a predetermined threshold, controls the traveling inverter so as not to generate the regenerative power and does not operate the converter. 2. The electrically driven vehicle according to claim 1,
The loading platform and
a sensor for detecting the amount of cargo on the loading platform;
the controller, when detecting the coasting state and the load amount being equal to or greater than a predetermined threshold, controls the driving inverter so as not to generate the regenerative power and does not operate the converter. 2. The electrically driven vehicle according to claim 1,
a sensor for detecting a downward inclination angle of a running surface;
A storage battery and
a charge/discharge controller that supplies and receives electric power between the storage battery and the auxiliary circuit;
The controller
when the coasting state is detected and the descending slope angle is equal to or greater than a predetermined first threshold value and less than a predetermined second threshold value, the driving inverter is controlled so that the regenerative power matches the drive power of the auxiliary motor, the converter is operated, and the auxiliary inverter and the charge/discharge controller are controlled so that the regenerative power is supplied only to the auxiliary motor;
when the coasting state is detected and the descending slope angle is equal to or greater than the second threshold, the driving inverter is controlled so that the regenerative power is greater than the drive power, the converter is operated, and the auxiliary inverter and the charge/discharge controller are controlled so that the regenerative power is supplied to the auxiliary motor and the storage battery. 2. The electrically driven vehicle according to claim 1,
The loading platform and
a sensor for detecting the amount of cargo on the loading platform;
A storage battery and
a charge/discharge controller that supplies and receives electric power between the storage battery and the auxiliary circuit;
The controller
When the coasting state is detected and the load amount is equal to or greater than a predetermined threshold, the driving inverter is controlled so that the regenerative power matches the drive power of the auxiliary motor, the converter is operated, and the regenerative power is supplied only to the auxiliary motor;
when the coasting state is detected and the load amount is less than the threshold, the driving inverter is controlled so that the regenerative power is greater than the drive power, the converter is operated, and the auxiliary inverter and the charge/discharge controller are controlled so that the regenerative power is supplied to the auxiliary motor and the storage battery.