WO2015098545A1

WO2015098545A1 - Hybrid type work vehicle

Info

Publication number: WO2015098545A1
Application number: PCT/JP2014/082846
Authority: WO
Inventors: 浩志歌代; 徳孝伊藤; 秀一森木
Original assignee: 日立建機株式会社
Priority date: 2013-12-24
Filing date: 2014-12-11
Publication date: 2015-07-02
Also published as: JP2015120437A; JP6276021B2

Abstract

A hybrid type work vehicle is provided with: a running electric motor; an electricity storage device that is charged with regenerative electric power generated by the running electric motor and that supplies driving electric power to the running electric motor; an electric generator/motor that generates electric power by being driven by an engine in electric power generation mode and that is driven with the regenerative electric power in powering mode; a hydraulic pump mechanically connected to and driven by the electric generator/motor and the engine; a speed level setting device that sets any of a plurality of speed levels; and a control device that drivingly controls the running electric motor and the electric generator/motor. The control device includes a drive control unit that implements regenerative control by computing a greater regenerative braking force as the speed level that is set becomes lower, on the basis of drive torque characteristics with respect to a rotating speed set for each speed level, and regenerative braking force characteristics with respect to a vehicle speed set for each speed level.

Description

Hybrid work vehicle

The present invention relates to a hybrid work vehicle.

2. Description of the Related Art Conventionally, a series hybrid work vehicle that travels by supplying electric power from a generator mechanically connected to an engine to a traveling motor and that performs regenerative braking is known (for example, Patent Documents). 1).

International Publication WO2012-099255

However, the work vehicle of Patent Document 1 does not have a speed stage of a transmission unlike a torque converter vehicle because of a configuration in which a traveling motor is driven to travel. Therefore, for an operator who is used to a torque converter vehicle, a work vehicle driven by a traveling motor has a different traveling feeling. Therefore, if the hybrid vehicle is set to the same speed stage as that of the torque converter vehicle and the brake force corresponding to the driving feeling corresponding to the speed stage similar to that of the torque converter vehicle is obtained by the regenerative braking force, the output performance of the traveling motor is obtained. Regenerative braking force exceeding 1 is required. During power running, it is possible to set a driving feeling corresponding to the speed stage similar to that of a conventional torque converter vehicle. However, when a regenerative braking force equivalent to an engine brake is to be obtained, it is necessary to output a force exceeding the maximum performance. Particularly at a small speed stage, it is difficult to obtain a regenerative braking force similar to the braking force of a torque converter vehicle. This is due to the limitation of the volume of the traveling motor when mounted on the vehicle body.
It is an object of the present invention to provide a hybrid work vehicle that can obtain a sufficient regenerative braking force that matches a speed stage in the same manner as a conventional torque converter vehicle.

According to the first aspect of the present invention, the hybrid work vehicle includes a traveling motor that applies traveling driving torque to the wheels, and a power storage device that is charged by regenerative power generated by the traveling motor and supplies driving power to the traveling motor. In the power generation mode, the power is driven by the engine to generate power. In the power running mode, the generator motor is driven by regenerative power from the traveling motor, and is driven by being mechanically connected to the generator motor and the engine. A hydraulic pump that supplies pressure oil to the vehicle, a speed stage setting device that sets one of a plurality of speed stages, and a control device that controls driving of the traveling motor and the generator motor. The control apparatus is set for each speed stage. Based on the characteristics of the drive torque with respect to the set number of revolutions and the characteristics of the regenerative braking force with respect to the vehicle speed set for each speed stage. It calculates a smaller large regenerative braking force with a driving control unit that performs regeneration control.
According to the second aspect of the present invention, the hybrid work vehicle according to the first aspect further includes a braking device that applies a frictional braking force to the wheels, and the control device has a regenerative braking force calculated in the regenerative control, It is preferable to further include a braking control unit that controls the braking device so as to add an insufficient braking force when the vehicle speed exceeds an upper limit value that is set to a smaller value as the vehicle speed increases.
According to the third aspect of the present invention, in the hybrid work vehicle according to the second aspect, when the rotational speed of the generator motor is equal to or higher than a predetermined value, the control device determines the regenerative power charged in the power storage device according to the rotational speed. It is preferable to further include a charge control unit that performs regenerative power restriction control to limit the regenerative braking force, and the upper limit value of the regenerative braking force is determined by regenerative power restriction control.
According to the fourth aspect of the present invention, in the hybrid work vehicle according to the second or third aspect, the control device compares the electric power that can be charged to the power storage device in a region where the rotational speed of the generator motor is higher than a predetermined value. When the regenerative power is large, the generator motor is controlled so that the surplus power is consumed by the generator motor, and the reduction amount of the regenerative power consumed by the generator motor according to the amount of deviation between the rotation speed and the predetermined value It is preferable to further include a power generation control unit that performs control to greatly reduce the deviation amount as the deviation amount increases, and the braking control unit performs control to apply a frictional braking force corresponding to the reduction amount of the regenerative power to the wheels.
According to a fifth aspect of the present invention, in the hybrid work vehicle according to any one of the second to fourth aspects, the control device includes an accelerator required torque calculated based on an accelerator pedal depression amount and a vehicle speed, and a brake pedal. The travel request torque is calculated based on the regenerative braking torque calculated based on the stepping amount of the engine and the regenerative braking torque calculated based on the speed stage, and the rotation is performed in a region where the rotational speed of the generator motor is higher than the predetermined value. The amount of regenerative power consumed by the generator motor is calculated according to the difference between the number and the predetermined value, the regenerative reduction torque is calculated by converting the amount of regenerative power reduction by the number of revolutions of the traveling motor, and the required travel torque Subtract the regenerative reduction torque calculated from, calculate the running motor torque command, and subtract the running motor torque command from the required travel torque to calculate the insufficient braking torque Calculates the braking signal the braking force braking device adds the missing brake control device preferably controls the driving of the braking device by the braking signal.

According to the present invention, the characteristics of the regenerative braking force with respect to the vehicle speed are made different for each of the plurality of speed stages, and a larger regenerative braking force is obtained as the set speed stage is smaller. Therefore, when descending a steep slope, a sufficient regenerative braking force that matches the speed stage can be obtained in the same manner as a conventional torque converter vehicle.

FIG. 2 is an external side view of a hybrid work vehicle according to an embodiment of the present invention. Circuit block diagram of hybrid work vehicle according to embodiment Block diagram explaining the functions of the main controller The figure which shows an example of an allowable charging power map Figure showing an example of the pump request flow map The figure which shows an example of an accelerator demand torque map The figure explaining regenerative braking power with respect to vehicle speed The flowchart explaining operation | movement of the hybrid type work vehicle by 1st Embodiment. The circuit diagram explaining the hydraulic circuit of the hybrid type work vehicle by 2nd Embodiment The figure explaining the relationship between the rotation speed of a cooling fan and the temperature of hydraulic fluid The figure explaining the rotation speed of the cooling fan controlled according to the temperature of hydraulic oil and the required regenerative braking force The flowchart explaining operation | movement of the hybrid type work vehicle by 2nd Embodiment.

-First embodiment-
A hybrid work vehicle according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external side view of a wheel loader shown as an example of a hybrid work vehicle 200 according to the embodiment, and FIG. 2 is a circuit block diagram showing a main configuration of the hybrid work vehicle 200.

As shown in FIG. 1, a hybrid work vehicle 200 includes a front vehicle body 202 having an arm 201, a bucket 20,

front wheels

18a, 18b and the like, and a rear vehicle body 203 having a cab 19,

rear wheels

18c, 18d and the like. Have. The arm 201 rotates up and down (up and down) by driving the arm cylinder 13, and the bucket 20 rotates up and down (dump or cloud) by driving the bucket cylinder 14. The

front wheels

18a and 18b and the

rear wheels

18c and 18d will be described as wheels 18 when collectively referred to.

The front vehicle body 202 and the rear vehicle body 203 are rotatably connected to each other by a connection shaft (not shown). This hybrid work vehicle 200 is an articulated work vehicle in which a front vehicle body 202 and a rear vehicle body 203 are bent at a connecting shaft. One end and the other end of a pair of steering cylinders (hereinafter referred to as steering cylinders) 12 around the connecting shaft are rotatably locked to the front vehicle body 202 and the rear vehicle body 203, respectively. One of the pair of steering cylinders 12 is extended and the other is retracted by a hydraulic device to be described later, thereby rotating the front vehicle body 202 and the rear vehicle body 203 about the connecting shaft. As a result, the relative mounting angle between the front vehicle body 202 and the rear vehicle body 203 changes, and the vehicle body bends and turns.

As shown in FIG. 2, the hybrid work vehicle 200 includes an engine 1, an engine control device (hereinafter referred to as an engine controller) 2 that controls driving of the engine 1, a power storage device (hereinafter referred to as a capacitor) 3, a converter 4, and a generator motor 5. , A power generation inverter 6, traveling

motors

7 F and 7 R,

traveling inverters

8 F and 8 R, a hydraulic pump 9, an operating device 31, and a shift switch 40. The hybrid work vehicle 200 includes a main control device (hereinafter referred to as a main controller) 100 that controls the above components.

The hydraulic pump 9 is a variable displacement hydraulic pump that supplies pressure oil to each hydraulic actuator of the hybrid work vehicle 200, that is, the steering cylinder 12, the lift cylinder 13, and the bucket cylinder 14. The rotation shaft of the hydraulic pump 9 is provided coaxially with the drive shaft of the engine 1. When the hydraulic pump 9 is driven by the engine 1, hydraulic oil in the oil tank 10 is supplied to the steering cylinder 12, the lift cylinder 13, and the bucket cylinder 14 via the control valve 11. The control valve 11 is a control valve that controls the flow of hydraulic oil to the bottom chamber or the rod chamber of the steering cylinder 12, the lift cylinder 13 and the bucket cylinder 14. The control valve 11 is controlled by a signal (hydraulic signal or electric signal) output from an operating device 31 installed in the cab 19. The hydraulic fluid guided from the hydraulic pump 9 to the control valve 11 is distributed to the steering cylinder 12, the lift cylinder 13 and the bucket cylinder 14 in accordance with the operation of the operating device 31.

In the generator motor 5, a rotor is attached to a rotating shaft that is coaxial with the drive shaft of the engine 1, and a stator is disposed on the outer periphery of the rotor. The generator motor 5 is driven in either a generator mode or a motor mode. When the generator mode is selected, the generator motor 5 generates power when the rotor is rotated by the engine 1. The generator inverter 6 converts AC power generated by the generator motor 5 into DC power having a predetermined voltage. When the motor mode is selected, the generator motor 5 is supplied with AC power from the generator inverter 6 and functions as a motor. The rotating shaft of the generator motor 5 is connected to the rotating shaft of the engine 1 and the rotating shaft of the hydraulic pump 9. Therefore, the output torque of the generator motor 5 is given to the hydraulic pump 9.

The converter 4 boosts DC power obtained from the electric charge stored in the capacitor 3 to a predetermined voltage and supplies it to the generator motor 5 and the

traveling motors

7F and 7R. The converter 4 is controlled by a main controller 100 described later.
Instead of the capacitor 3, a secondary battery such as a lead storage battery or a lithium ion battery may be used. A power generation brake such as a retarder may be connected to the power line between the power generation inverter 6 and the travel inverter 8. In this case, the regenerative energy is converted into heat.

The traveling

motors

7F and 7R are connected to the capacitor 3 and the generator motor 5 via a power line, and drive the wheels 18 with electric power supplied from one or both of the capacitor 3 and the generator motor 5. At the time of traveling acceleration, the traveling

motors

7F and 7R are powered by driving

inverters

8F and 8R described later. The power running torque generated by the power running drive is transmitted to the

front wheels

18a, 18b and the

rear wheels

18c, 18d via the

propeller shafts

15f, 15r, the

differential gears

16f, 16r and the

drive shafts

17a, 17b, 17c, 17d, and the hybrid work The vehicle 200 is accelerated. At the time of traveling braking, the regenerative torque (braking torque) generated by the traveling

electric motors

7F and 7R is transmitted to the wheels 18 and the hybrid work vehicle 200 is decelerated.

The traveling

inverters

8F and 8R are driven by supplying AC traveling driving power to the traveling

motors

7F and 7R during traveling acceleration, respectively. Further, the traveling

inverters

8F and 8R convert the regenerative power (AC power) generated by the traveling

motors

7F and 7R during traveling braking into DC power having a predetermined voltage and supply it to the capacitor 3. Converter 4, power generation inverter 6 and traveling

inverters

8F and 8R are connected to the same power line and configured to be able to supply power to each other. Converter 4 also monitors the DC voltage (DC voltage) of a smoothing capacitor (not shown) attached to the power line, and controls charging / discharging of capacitor 3 so as to keep the DC voltage of the smoothing capacitor constant.

The operating device 31 provided in the cab 19 includes a steering wheel, a lift lever, a bucket lever, and the like. The steering wheel is operated when the steering cylinder 12 is expanded and contracted. The operator operates the steering wheel to expand and contract the steering cylinder 12 to adjust the steering angle of the hybrid work vehicle 200 and turn the hybrid work vehicle 200. The lift lever is operated when the lift cylinder 13 is expanded and contracted. The bucket lever is operated when the bucket cylinder 14 is expanded and contracted. The operator operates the lift lever, bucket lever and the like to expand and contract the lift cylinder 13 and the bucket cylinder 14 to control the height and inclination of the bucket 20 to perform excavation and loading work.

The cab 19 is provided with a shift switch 40, an accelerator pedal (not shown), a brake pedal, and a forward / reverse switch operation unit. The operator can set the speed stage between the first speed and the third speed by operating the shift switch 40, for example. The shift switch 40 outputs a signal (speed stage signal) indicating the set speed stage to the main controller 100 described later. The operator can drive the hybrid work vehicle 200 by driving the wheels 18 by operating the shift switch 40, the accelerator pedal, the brake pedal, and the forward / reverse switch operation unit. The depression amount of the accelerator pedal is detected by a sensor 290 that outputs an accelerator signal according to the depression amount of the accelerator pedal, and the depression amount of the brake pedal is detected by a sensor 291 that outputs a brake signal according to the depression amount of the brake pedal. These

sensors

290 and 291 respectively output an accelerator signal and a brake signal to the main controller 100 described later in accordance with an operation amount by the operator, that is, a depression amount. The forward / backward switch 292 detects that the forward / reverse switch operation unit has been operated forward or backward, and the forward / backward switch 292 transmits a forward signal or a reverse signal to the main controller 100.

In the hybrid work vehicle 200 according to the present embodiment, a predetermined hydraulic pressure is introduced into the hydraulic

brake control valves

35a and 35b according to the operation of the brake pedal, and the

hydraulic brakes

36a and 36b, which are disc brakes, generate frictional force. The rotation of the

wheels

18a and 18b is mechanically braked. And the regenerative braking force by the regenerative torque of the traveling

motors

7F and 7R described above is also taken into consideration.

The speed sensor 21 detects the traveling speed of the hybrid work vehicle 200 and outputs a speed signal to the main controller 100. The motor rotation speed sensor 22 detects the rotation speed of the traveling

motors

7F and 7R, A motor rotation number signal is output to the main controller 100.

The main controller 100 includes a CPU, a ROM, a RAM, and the like, and is an arithmetic circuit that controls each component of the hybrid work vehicle 200 based on a control program and executes various data processing. Further, the main controller 100 performs vehicle speed control using the accelerator signal, the brake signal, and the speed stage signal respectively input from the accelerator pedal depression amount sensor 290, the brake pedal depression amount sensor 291 and the shift switch 40 described above.

As shown in FIG. 3, the main controller 100 includes a power storage management unit 110, a hydraulic pressure request calculation unit 120, a travel request calculation unit 130, an output management unit 140, a target rotational speed calculation unit 150, and a generator motor control unit. 160, a tilt angle control unit 170, a traveling motor / brake control unit 180, and a brake control unit 190 are functionally provided.

Main notations used in the following formulas (1) to (14) are as follows.
"Torque" T _rq
“Output” P _wr
"Pump" P _pmp
"Running" _drv
"Accel" _acc
"Power generation" _gen
"Request" _req
“Command (target value)” _t
“Travel motor”, “Regenerative power” _mot

Hydraulic pressure required output P _{wr_pmp_req} (1) Accelerator required torque T _{rq_acc_req} ... Accelerator required torque map of FIG. 6 Travel required torque T _{rq_drv_req} (2) Formula Travel required output P _{wr_drv_req} (3) Engine output command P _{wr_eng_t} (3) 9) Formula Regenerative power reduction command dP _{wr_mot_t} (6) Formula Power generation output command P _{wr_gen_t} (8) Formula Generator motor torque command T _{rq_gen_t} (10) Formula Running motor torque command T _{rq_mot_t} (12) Formula Engine speed command N _{eng_t}
Brake torque command T _{rq_brk_t} (13) Engine speed N _eng
Running motor speed N _mot

-Allowable charging power-
The power storage management unit 110 calculates the allowable charging power of the capacitor 3 and outputs it to the output calculation unit 140. The storage voltage of the capacitor 3 detected by the converter 4 is input to the storage management unit 110. The power storage management unit 110 calculates the allowable charging power of the capacitor 3 based on the storage voltage of the capacitor 3 input from the converter 4 and the allowable charging power map stored in a storage device (not shown) in the main controller 100. To do.

FIG. 4 shows an example of the allowable charging power map. In FIG. 4, Vcmin and Vcmax are the lowest voltage and the highest voltage in the use range where the capacitor 3 is unlikely to deteriorate. The allowable charging power map is set so that the allowable charging power becomes 0 or less near the maximum voltage Vcmax so that the stored voltage of the capacitor 3 does not exceed the maximum voltage Vcmax. On the other hand, in FIG. 4, Icmax is set based on the maximum current limit of converter 4. The allowable charging power map is also set such that the allowable charging power decreases as the stored voltage decreases so that the charging current does not exceed the maximum current limit Icmax.
In addition, although the above demonstrates the example at the time of charge, the same calculation is performed also at the time of discharge.

-Hydraulic demand calculation unit 120-
The hydraulic pressure request calculation unit 120 calculates the hydraulic pressure request output P _{wr_pmp_req} of the hydraulic pump 9. The hydraulic pressure request calculation unit 120 receives a lift lever and a bucket lever, that is, a lever signal from the operation device 31, and a pump pressure p _pmp from a pressure sensor (not shown) provided between the hydraulic pump 9 and the control valve 11. Is entered. In order to simplify the description, the operation of the steering wheel and the operation of the steering cylinder 12 are not included in the calculation.

FIG. 5 is a diagram illustrating an example of a pump request flow map. The pump request flow map is set so that the pump request flow is substantially proportional to the lever signal, and is stored in a storage device (not shown) of the main controller 100. The hydraulic pressure request calculation unit 120 calculates the pump required flow rate q _{pmp_req} based on the received lever signal and the pump required flow rate map. The hydraulic demand calculation unit 120 includes a pump required flow _{q Pmp_req} the calculated, received using a pump pressure _{p pmp,} calculates the oil pressure required output _{P Wr_pmp_req} by the following equation (1).
_{_{_{P wr_pmp_req = q pmp_req · p pmp}}} ... (1)
In order to simplify the description, it is assumed that the efficiency of the hydraulic pump 9 is not taken into account, and the efficiency of the hydraulic pump 9 is not included in the following calculation formula as well.

-Running request calculation unit 130-
The travel request calculation unit 130 calculates and outputs a travel request torque T _{rq_drv_req} that is a torque required for the

travel motors

7F and 7R during travel based on the formula (2), and is consumed or generated by the travel motor 7 during travel ( The travel request output P _{wr_drv_req} which is the electric power to be regenerated is calculated based on the equation (3) and output. At this time, the travel request calculation unit 130 performs a calculation using an accelerator request torque map stored in a storage device (not shown) of the main controller 100.

FIG. 6 shows an example of the accelerator required torque map. The accelerator required torque map is provided for each speed stage. (A) is the first speed, (b) is the second speed, and (c) is the third speed. Accelerator required torque T _{rq_acc_req} is calculated based on the accelerator signal and the absolute value of the rotational speed of traveling

electric motors

7F and 7R. That is, the travel request calculation unit 130 is a speed sensor that corresponds to the speed stage signal input from the shift switch 40, the accelerator signal input from the sensor 290 that detects the depression amount of the accelerator pedal, and the travel speed of the vehicle. On the basis of the traveling motor rotation speed N _mot input from 22, the accelerator request torque map corresponding to the set speed stage is selected to calculate the accelerator request torque T _{rq_acc_req} . Then, the travel request calculation unit 130 travels input from the rotational speed sensor 22 corresponding to the calculated accelerator request torque T _{rq_acc_req} , the forward / reverse switch signal V _FNR input from the forward / reverse switch, and the travel speed of the vehicle. a motor speed _{N mot,} with a brake signal _{V brk} inputted from a sensor 291 for detecting the amount of depression of the brake pedal, calculates the travel required torque _{T Rq_drv_req} by the following equation (2).
T _{rq_drv_req} = sign (V _FNR ) · T _{rq_acc_req} −sign (N _mot ) · K _brk · V _brk
-Sign (N _mot ) · α · N _mot (2)
However, sign is a sign function, and “1” is returned when the argument is positive, “−1” is returned when it is negative, and “0” is returned when it is 0. Further, the forward / reverse switch signal _VFNR indicates “1” when the forward / reverse switch is in the forward direction, “−1” when it is in the reverse direction, and “0” when it is neutral. _Kbrk is a proportionality constant, and is set in advance so that deceleration without excess or deficiency can be obtained by operating the brake pedal. Α is a function of the speed stage and the accelerator pedal depression amount, and a larger value is set as the speed stage is smaller, and a larger value is set as the accelerator pedal depression amount is smaller.

The third term on the right side of Equation (2) is introduced to obtain an engine brake feeling equivalent to the engine brake obtained in a torque converter vehicle in a hybrid wheel loader. For example, in the embodiment of the present invention, as shown in FIG. 7, a regenerative braking force corresponding to the vehicle speed similar to that of a torque converter vehicle is obtained. FIG. 7 shows the regenerative braking force for the first speed, the second speed, and the third speed when neither the accelerator pedal nor the brake pedal is depressed.
However, as will be described later, it is not possible to charge the capacitor 3 with all of the regenerative power during high-speed traveling. For this reason, in regenerative operation during high-speed traveling, control for reducing regenerative power is performed as described in Equation (6). As a result, as will be described in detail later with reference to FIG. 7B, the regenerative braking force is limited by its upper limit line L4, and the regenerative braking forces L1 to L3 of each speed stage have a maximum value on the upper limit line L4. Limited. Therefore, in the present invention, the shortage above the line L4 in FIG. 7C is compensated by the hydraulic brake. These controls will be described later in detail.

Traveling to the request operation unit 130, and the DC voltage _{V DC} detected by the converter 4, the running inverter 8F, running a direct current (DC _{current) I DC_mot} is detected by the 8R are input. However, the traveling DC current is a DC current flowing through the power line side of the traveling

inverters

8F and 8R, where the consumption side is positive and the regeneration side is negative. Travel request calculating unit 130 uses the DC voltage _{V DC,} and a travel DC current _{I DC_mot,} calculates the following (3) travel request output _{P Wr_drv_req} by formula.
P _{wr_drv_req} = V _DC · I _{DC_mot} (3)
According to the equation (3), the travel request output P _{wr_drv_req} during the regenerative operation takes a negative value.

-Output management unit 140-
The output management unit 140 includes an engine speed N _eng from the engine controller 2, an allowable charging power P _{wr_chg_max} from the power storage management unit 110, a hydraulic pressure request output P _{wr_pmp_req} from the hydraulic pressure request calculation unit 120, and a travel request calculation unit The travel request output P _{wr_drv_req} from 130 is input.
The output management unit 140 calculates surplus power P _{wr_sup} based on equation (4). Further, the tilt angle increase command dD _pmp is calculated and output based on the equation (5), the regenerative power reduction command dP _{wr_mot_t} is calculated and output based on the equation (6), and based on the equation (8). The power generation output command _{Pwr_gen_t} is calculated and output, and the engine output command _{Pwr_eng_t} is calculated and output based on the equation (9).
The output management unit 140 receives the engine speed and uses it for calculation. However, since the engine 1, the generator motor 5 and the hydraulic pump 9 are mechanically connected, the generator motor is used instead of the engine speed. 5 and the number of rotations of the hydraulic pump 9 may be appropriately received via a sensor or the like and used for calculation.

(Surplus power)
The output management unit 140 receives the travel request output P _{wr_drv_req} calculated by the travel request calculation unit 130 using equation (3). If the travel request output _{Pwr_drv_req} is 0 or more, the output management unit 140 determines that the hybrid work vehicle 200 is in a power running operation, and if the travel request output _{Pwr_drv_req} is negative, the hybrid work vehicle 200 is in a regenerative operation. Judge. When it is determined that the hybrid work vehicle 200 is in regenerative operation, the output management unit 140 uses the allowable charging power P _{wr_chg_max} from the power storage management unit 110 and the travel request output P _{wr_drv_req} from the travel request calculation unit 130 to be described below. The surplus power P _{wr_sup} is calculated by the equation (4).
P _{wr_sup} = max (| P _{wr_drv_req} | −P _{wr_chg_max} , 0) (4)

When the absolute value of the travel request output P _{wr_drv_req} at the time of regeneration is larger than the allowable charging power P _{wr_chg_max} , the difference is calculated as the surplus power P _{wr_sup} .
In other words, the surplus power P _{wr_sup} is the power at which the regenerative power by the traveling

motors

7F and 7R during the regenerative operation exceeds the allowable charge power that can charge the capacitor 3. Therefore, it is necessary to drive the generator motor 5 to consume this surplus power, or to reduce the regenerative power itself to reduce the surplus power itself.
Consumption of surplus power P _{wr_sup} is consumed by driving the generator motor 5 with the generator motor torque command T _{rq_gen_t} calculated by the equation (10). Further, the surplus power _{P Wr_sup} is reduced by the regenerative power reduction command calculated from the difference between the engine speed _{N eng} and its second threshold value _{_N eng_th2 _(N} eng _-N _{eng_th2)} in equation (6). This point will be described in detail later.

The output management unit 140 monitors whether or not the calculated surplus power P _{wr_sup} is 0, so that it is possible to charge all the regenerative power generated in the traveling

motors

7F and 7R to the capacitor 3, that is, surplus power P _{wr_sup.} It is determined whether or not the error occurs. However, when it is determined that the power running is in _progress , the surplus power P _{wr_sup} is set to zero.
That is, the output management unit 140 can recognize the following from the surplus power _{Pwr_sup} calculated by the equation (4).
(A) When the surplus power _{Pwr_sup} is 0, it is recognized that the capacitor 3 can be charged with regenerative power.
(B) When the surplus power P _{wr_sup} is not 0, it is recognized that the capacitor 3 cannot be charged with regenerative power.
When recognizing (b), the output management unit 140 drives the generator motor 5 in the electric mode to consume regenerative power, or reduces the surplus power itself by a regenerative power reduction command.

(Engine speed determination)
When the output management unit 140 determines that the hybrid work vehicle 200 is in a regenerative operation, the output management unit 140 determines whether the rotational speed N _eng of the engine 1 is equal to or _lower than the first set threshold value N _{eng_th1} or further equal to or _lower than the second set threshold value N _{eng_th2.} judge. Here, the first set threshold value N _{eng_th1} and the second set threshold value N _{eng_th2} are _{expressed as} follows: “idle speed of engine 1 <first set threshold value N _{eng_th1} <second set threshold value N _{eng_th2} <min (maximum engine speed of engine 1, hydraulic pressure It is set so as to satisfy the “maximum rotational speed of the pump 9)”. The first setting threshold N _{eng_th1} and the second setting threshold N _{eng_th2} are stored in the storage device of the main controller 100, and can be reset as appropriate. Instead of the rotation speed of the engine 1, the rotation speed of the generator motor 5 may be used, or the rotation speed of the hydraulic pump 9 may be used.

The output management unit 140 _compares the input engine speed, the first setting threshold N _{eng — th1} and the second setting threshold N _{eng — th2,} and determines whether the engine 1 is in the low rotation mode, the rotation suppression mode, or the high rotation mode. Determine whether. In this case, if the rotation speed N _eng of the engine 1 is equal to or less than the first set threshold value N _{eng —} _th1 , the output management unit 140 determines that the engine 1 is in the low rotation mode. If the rotational speed _{N eng} of the engine 1 and the second set threshold value _{N Eng_th2} less greater than the first preset threshold _{N eng_th1,} output management unit 140 determines the engine 1 and the rotation suppression mode. When the rotation speed N _eng of the engine 1 is larger than the second setting threshold N _{eng —} _th2 , the output management unit 140 determines that the engine 1 is in the high rotation mode.

When it is determined that the hybrid work vehicle 200 is in a power running operation, the output management unit 140 determines that the engine 1 is in the normal mode regardless of the magnitude of the engine speed N _eng .
As described above, in the hybrid work vehicle 200 of this embodiment, the operation mode of the engine 1 is classified into the following four modes.
At the time of regenerative operation, it is classified into a low rotation mode, a rotation suppression mode, and a high rotation mode.

(Excavator operation judgment)
The output management unit 140 determines which one of the lift cylinder 13 and the bucket cylinder 14 is in operation based on the hydraulic request output P _{wr_pmp_req} calculated from the equation (1) by the hydraulic request calculation unit 120. If the required hydraulic pressure output P _{wr_pmp_req} is equal to or greater than a set value calculated by, for example, pump pressure × minimum discharge flow rate, the output management unit 140 determines that the lift cylinder 13 and the bucket cylinder 14 are operating.

_Instead of the hydraulic pressure request output P _{wr_pmp_req} , the operation of the operation device 31 may be detected to determine which one of the lift cylinder 13 and the bucket cylinder 14 is operating. In this case, a sensor for detecting that the lever signal is output from the operation device 31 is provided, for example, when the lever signal is a hydraulic signal, a pressure sensor is provided, and the output management unit 140 uses the detection value detected by the sensor. Thus, it may be determined that any of the cylinders 13 to 14 is operating. Moreover, the sensor which detects the expansion-contraction speed of the lift cylinder 13 and the bucket cylinder 14 may be provided, and the output management part 140 may determine using the detection speed detected by the sensor.

(Tilt angle increase command)
Further, the output management unit 140 outputs a tilt angle increase command dD _{pmp_t} for increasing the tilt angle of the hydraulic pump 9 when the following three conditions (i) to (iii) are satisfied: Calculate according to
(I) It is determined that the hybrid work vehicle 200 is in regenerative operation.
(Ii) When the generator motor 5 is driven by the surplus power of the traveling

motors

7F and 7R, it is determined that neither the lift cylinder 13 nor the bucket cylinder 14 is in operation.
(Iii) The engine 1 is determined to be in the high rotation mode.

Output management unit 140 calculates the engine speed _{N eng} input from the engine controller 2, by using the first set threshold value _{N Eng_th1,} the tilt angle increase instruction _{dD Pmp_t} by the following expression (5).
dD _{pmp_t} = max {K _nD (N _eng −N _{eng —} _th1 ), 0} (5)
However, K _nD is a proportional constant for calculating a tilt angle increase command from the difference between the first set threshold value N _{eng —} _th1 and the actual rotational speed N _eng , and is stored in the main controller 100 in advance.

Even when the motor generator 5 is driven by the surplus power of the traveling

motors

7F and 7R, if either the lift cylinder 13 or the bucket cylinder 14 is operating, the output management unit 140 The tilt angle increase command dD _{pmp_t} is set to 0. In addition, when it is determined that the power running operation is being performed, the output management unit 140 sets the tilt angle increase command dD _{pmp_t} to 0. Further, during the regenerative operation, when the total amount of regenerative power cannot be charged in the capacitor 3 and the surplus power is not 0 and the load of the hydraulic pump 9 is small, the output management unit 140 calculates by the equation (5). The tilt angle increase command dD _{pmp_t} is output. As a result, the tilt angle of the hydraulic pump 9 is increased and the consumption of surplus power is increased.

If during regenerative operation based on the above equation (5) tilt angle increase instruction _{dD Pmp_t} is calculated, the tilt angle increase instruction _{dD Pmp_t} as the engine rotational speed _{N eng} is increased becomes larger, the discharge of the hydraulic pump 9 Capacity increases. As a result, as the engine speed N _eng increases, the load torque of the hydraulic pump 9, that is, the regenerative power consumption can be increased. As a result, the regenerative braking force also increases.

(Regenerative power reduction directive)
The output management unit 140 reduces the regenerative torque generated by the traveling

motors

7F and 7R when the generator motor 5 is driven by the surplus power of the traveling

motors

7F and 7R and the engine 1 is determined to be in the high rotation mode. The regenerative power reduction command dP _{wr_mot_t} is calculated. The output management unit 140 uses the engine speed N _eng input from the engine controller 2 and the second set threshold value N _{eng —} _th2 to calculate a regenerative power reduction command (regenerative power reduction target value) dP according to the following equation (6). _{wr_mot_t} is calculated.
dP _{wr_mot_t} = max {K _nP (N _eng −N _{eng —} _th2 ), 0} (6)
In Equation (6), K _nP is a proportionality constant that calculates a regenerative power reduction command from the difference between the second set threshold value N _{eng —} _th2 and the actual engine speed N _eng .
When the engine 1 is in any of the normal mode, the low rotation mode, and the rotation suppression mode, the output management unit 140 sets the regenerative power reduction command dP _{wr_mot_t} to 0.

When the above (6) regenerative power reduction command _{dP Wr_mot_t} based on equation are calculated, as the engine rotational speed _{N eng} is increased, the regenerative power reduction command _{dP Wr_mot_t} increases, traveling motor 7F, the regenerative power of the 7R small Become. As a result, the surplus power P _{wr_sup} can be reduced as the engine speed N _eng increases.
The regenerative power reduction command control is performed when the engine 1 is traveling in a high speed range, for example, when the work vehicle 200 enters a regenerative operation by releasing the accelerator pedal, and the surplus power P _{wr_sup.} It is possible to prevent over-rotation of the engine speed N _{eng due to} the excessively large.

(power consumption)
When it is determined that the hybrid work vehicle 200 is in the regenerative operation, the output management unit 140 uses the power consumption P _{wr_cns} that is the power that should be consumed by the generator motor 5 among the regenerative power generated by the traveling

motors

7F and 7R. calculate. The output management unit 140 calculates the power consumption P _{wr_cns} from the following formula (7) using the surplus power P _{wr_sup} calculated by the formula (4) and the regenerative power reduction command dP _{wr_mot_t} calculated by the formula (6). To do.
P _wr — _cns = max (P _{wr — sup} −dP _wr — _mot — _t , 0) (7)
However, when it is determined that the hybrid work vehicle 200 is in power running, the output management unit 140 sets the power consumption P _{wr_cns} to 0.

When the power consumption P _{wr_cns} is calculated using the above equation (7), the output management unit 140 generates a power generation output command (power generation output) from the following equation (8) based on the travel request output P _{wr_drv_req} and the power consumption P _{wr_cns.} Target value) P _{wr_gen_t} is calculated.
P _wr — _gen — _t = max (P _wr — _drv — _req , 0) −P _{wr — cns} (8)

The power generation output command P _{wr_gen_t} calculated by the equation (8) at the time of power running operation and regenerative operation is summarized as follows.
During power running, the power consumption P _{wr_cns} is set to 0, and the travel request output P _{wr_drv_req} takes a positive value. Therefore, the power generation output command P _{wr_gen_t} of equation (8) is calculated by equation (3). The request output P _{wr_drv_req} is obtained. On the other hand, since the travel request output P _{wr_drv_req} takes a negative value during the regenerative operation, the power generation output command P _{wr_gen_t in the} equation (8) becomes the power consumption P _{wr_cns} calculated by the equation (7).
In other words, the power generation output command P _{wr_gen_t} during power running is the travel request output P _{wr_drv_req} , and the power generation output command P _{wr_gen_t} during regeneration is the power consumption P _{wr_cns} and takes a negative value.

The output management unit 140 uses the hydraulic pressure request output P _{wr_pmp_req} from the hydraulic pressure request calculation unit 120 and the power generation output command P _{wr_gen_t} calculated by the formula (8) to calculate an engine output command (engine output) by the following formula (9). Target value) _{Pwr_eng_t} is calculated.
_{Pwr_eng_t} = _{Pwr_pmp_req} + _{Pwr_gen_t} (9)

The engine output command P _{wr_eng_t} calculated by the equation (9) during the power running operation and the regenerative operation is summarized as follows.
Power running operation, the engine output command _{P Wr_eng_t} the output management unit 140 is calculated, the hydraulic request output _{P Wr_pmp_req} is the product of the pump required flow _{q Pmp_req} the pump pressure _{p pmp} ((1) is calculated by the formula), (8) becomes the plus power generation output command _{P Wr_gen_t} a travel request output _{P Wr_drv_req} calculated by the formula.
During regenerative operation, the engine output command _{P Wr_eng_t} the output management unit 140 is calculated, the hydraulic request output _{P Wr_pmp_req} is the product of the pump required flow _{q Pmp_req} the pump pressure _{p pmp} ((1) is calculated by the formula), The power generation output command P _{wr_gen_t} which is the power consumption P _{wr_cn} calculated by the equation (7) is added.
In other words, the engine output command _{P Wr_eng_t} of power running is obtained by adding the travel request output _{P Wr_drv_req} to the hydraulic request output _{P Wr_pmp_req,} the engine output command _{P Wr_eng_t} during regeneration is the power consumption _{P Wr_cns} from the hydraulic request output _{P Wr_pmp_req} Subtracted. When the hydraulic pressure request output P _{wr_pmp_req} is 0, the engine output command P _{wr_eng_t} becomes the power consumption P _{wr_cns} .

-Target rotational speed calculation unit 150-
The target rotational speed calculation unit 150 calculates an engine rotational speed command (engine rotational speed target value) N _{eng_t} to be transmitted to the engine controller 2. Based on the engine output command _{Pwr_eng_t} calculated by the output management unit 140, the target rotational speed calculation unit 150 calculates an operating point at which the engine efficiency is highest using a fuel consumption map such as an engine. Then, the target engine speed calculation unit 150 sets the engine speed at the calculated operating point as the engine speed command N _{eng — t} . When the engine controller 2 receives the engine speed command N _{eng — t} from the target speed calculator 150, the engine controller 2 rotates the engine 1 at the engine speed indicated by the engine speed command.

-Generator motor controller 160-
The generator motor controller 160 receives the engine speed N _eng from the engine controller 2, the power generation output command P _{wr_gen_t} from the output manager 140, and the engine speed command N _{eng_t} from the target speed calculator 150. Is done. Using these values, the generator motor control unit 160 calculates a generator motor torque command (generator motor torque target value) T _{rq_gen_t} by the following equation (10).
T _{rq_gen_t} = max {K _p (N _{eng —} _t −N _eng ), 0} −P _{wr — gen — t} / N _eng (10)
However, _{K p} is the proportional constant for calculating the generator motor torque from the difference between the engine speed _{N eng} and the engine rotational speed command _{N eng_t.}
Then, the generator motor control unit 160 transmits the calculated generator motor torque command T _{rq_gen_t} to the generator inverter 6. Thereby, the generator motor 5 is drive-controlled.

The generator motor torque command T _{rq_gen_t} calculated by the equation (10) during power running and regenerative operation is summarized as follows.
During power running, the engine speed command N _{eng —} _t is greater than the engine speed N _eng . Therefore, during power running, the generator motor control unit 160 subtracts the torque obtained by dividing the engine output command P _{wr_eng_t} by the engine speed N _eng from the required torque obtained by K _p (N _{eng_t} −N _eng ). Thus, the generator motor torque command T _{rq_gen_t} is calculated. The engine output command P _{wr_eng_t} during power running is _obtained by adding the travel request output P _{wr_drv_req} to the hydraulic pressure request output P _{wr_pmp_req} .
On the other hand, during regenerative operation, the engine speed command N _{eng —} _t is smaller than the engine speed N _eng . The engine output command P _{wr_eng_t} during regeneration is _obtained by adding the power consumption P _{wr_cns} to the hydraulic pressure request output P _{wr_pmp_req} . Therefore, the generator motor torque command T _{rq_gen_t} calculated by the generator motor controller 160 during the regenerative operation is a torque obtained by dividing the value _obtained by subtracting the power consumption P _{wr_cns} from the hydraulic pressure request output P _{wr_pmp_req} by the engine speed N _eng. .

-Tilt angle controller 170-
The tilt angle control unit 170 calculates a tilt angle control signal V _{Dp_t} based on the following equation (11), and drives a regulator (not shown) of the hydraulic pump 9 based on the tilt angle control signal. The tilt angle of the hydraulic pump 9, that is, the capacity is controlled. The tilt angle control unit 170 uses the engine speed N _eng from the engine controller 2, the pump request flow rate q _{pmp_req} from the hydraulic pressure request calculation unit 120, and the tilt angle increase command dD _{pmp_t} from the output management unit 140. Thus, the tilt angle control signal V _{Dp_t} is calculated by the following equation (11).
V _{Dp_t} = K _Dp {(q _{pmp_req} / N _eng ) + dD _{pmp_t} } (11)
K _Dp is a proportional constant for calculating a tilt control signal necessary for setting the tilt angle of the hydraulic pump as a target value.
In addition, when it is determined that the power running operation is being performed, the output management unit 140 sets the tilt angle increase command dD _{pmp_t} to 0. Further, during the regenerative operation, when the total amount of regenerative power cannot be charged in the capacitor 3 and the surplus power is not 0 and the load of the hydraulic pump 9 is small, the output management unit 140 calculates by the equation (5). The tilt angle increase command dD _{pmp_t} is output. As a result, the tilt angle of the hydraulic pump 9 is increased and the consumption of surplus power is increased.

When the tilt angle increase command dD _{pmp_t} is 0, that is, (1) when it is determined that the power running operation is being performed, or (2) the generator motor 5 is driven by the surplus power of the traveling

motors

7F and 7R, and the lift cylinder 13 When either of the bucket cylinder 14 and the bucket cylinder 14 is operating, the tilt angle control signal V _{Dp_t} is set as follows. That is, the tilt angle control signal V _{Dp_t} is set so that the actual pump discharge flow rate is maintained at the pump required flow rate requested by the operator via the operation device 31. Accordingly, the tilt angle of the hydraulic pump 9 increases the rotational speed of the engine 1, the generator motor 5 or the hydraulic pump 9 so that the discharge amount of the hydraulic pump 9 is maintained at a value required by the operator (pump required flow rate). It is controlled so as to become smaller in accordance with.

-Travel motor / brake control unit 180-
The travel motor / brake control unit 180 includes a travel request torque T _{rq_drv_req} calculated from the equation (2) by the travel request calculation unit 130, a travel motor rotational speed N _mot from the rotational speed sensor 22, and an output management unit 140. The regenerative power reduction command dP _{wr_mot_t} calculated from the equation (6) is input. The traveling motor / brake control unit 180 uses these values to calculate a traveling motor torque command T _{rq_mot_t} by the following equation (12).
T _{rq_mot_t} = sign (T _{rq_drv_req} ) · max {| T _{rq_drv_req} |
-( _{DP wr_mot_t} ) / | N _mot |, 0} (12)
However, sign is a sign function, and returns 1 when the argument is positive, “−1” when it is negative, and “0” when it is 0.

The traveling motor / brake control unit 180 transmits the calculated traveling motor torque command T _{rq_mot_t} to the traveling

inverters

8F and 8R. Thereby, the power running / regeneration of the traveling

motors

7F, 7R is controlled. That is, the travel motor / brake control unit 180 calculates the absolute value of the travel request torque T _{rq_drv_req} calculated by the equation (2) based on the accelerator pedal depression amount, the brake pedal depression amount, and the selected speed stage. . During power running, the travel request torque T _{rq_drv_req} is positive and the regenerative power reduction command dP _{wr_mot_t} is zero, so the travel motor torque command T _{rq_mot_t} calculated by the equation (12) becomes the travel request torque T _{rq_drv_req} .

During regenerative operation, when the total amount of regenerative power cannot be charged in the capacitor 3, the surplus power is not 0, and the engine is operated at a high speed _{equal to} or higher than the second set threshold N _{eng — th2} (the engine is in the high speed mode). ), The regenerative power reduction command value dP _{wr_mot_t} is calculated from the equation (6). The regenerative power reduction torque obtained by dividing the regenerative power reduction command dP _{wr_mot_t} by the absolute value of the travel motor rotation speed N _mot is subtracted from the absolute value | T _{rq_drv_req} | of the travel request torque. This subtraction result becomes a negative value when the travel request torque T _{rq_drv_req} is negative, and becomes a travel motor torque command T _{rq_mot_t} having a negative value _, that is, a regenerative braking torque command.

Further, the traveling motor / brake control unit 180 uses the traveling motor torque command T _{rq_mot_t} calculated from the equation (12), the requested traveling torque T _{rq_drv_req,} and the traveling motor rotation speed N _mot to _express the following equation (13). _{Is used} to calculate the braking torque command T _{rq_brk_t} .
T _{rq_brk_t} = max {−sign (N _mot ) · (T _{rq_drv_req} −T _{rq_mot_t} ), 0}
... (13)
However, sign is a sign function, and returns 1 when the argument is positive, “−1” when it is negative, and “0” when it is 0.

The braking torque command T _{rq_brk_t} is calculated as follows using the equation (13). First, the travel motor torque command T _{rq_mot_t} calculated by the equation (12) from the required travel torque T _{rq_drv_req} calculated by the equation (2) based on the accelerator pedal depression amount, the brake pedal depression amount, and the selected speed stage. Is subtracted. During the power running operation, the travel motor torque command T _{rq_mot_t} is the travel request torque T _{rq_drv_req} , so the braking torque command T _{rq_brk_} t is zero.
During the regenerative operation, both the travel request torque T _{rq_drv_req} and the travel motor torque command T _{rq_mot_t} are negative, and the absolute value of the travel request torque T _{rq_drv_req} is larger than the absolute value of the travel motor torque command T _{rq_mot_t.} _{rq_drv_req−} T _{rq_mot_t} ) is negative. The sign function {−sign (N _mot )} is “−1” when the motor is moving forward (forward rotation), and is “1” when the motor is moving backward (reverse rotation). Therefore, { _-sign (N _mot ) · (T _{rq_drv_req} −T _{rq_mot_t} )} is positive during regenerative operation during forward movement, and this positive value is selected and used as the braking torque command T _{rq_brk_t} during regenerative operation. The

Here, the regenerative braking force for each speed stage according to the present invention will be described in relation to the equations (2), (6), (12), and (13).
As described above, when the engine 1 is operated in the high rotation mode, the regenerative power reduction command dP _{wr_mot_t} is calculated based on the equation (6). The regenerative power reduction command dP _{wr_mot_t} is generated when the generator motor 5 is driven by surplus power and the engine speed N _eng driven by the generator motor 5 exceeds the second set threshold N _{eng_th2.} This reduces the regenerative power generated. The regenerative power reduction command dP _{wr_mot_t} increases as the engine speed N _eng increases. Here, when the rotational speeds of the traveling

motors

7F and 7R are large, that is, when the vehicle speed is high, the surplus electric power increases, and as a result, the engine rotational speed driven by the generator motor 5 also increases.
Thus, the regenerative power reduction command dP _{wr_mot_t} increases as the vehicle speed increases, which means that the regenerative power reaches its peak when the vehicle speed is high. Since electric power is represented by the product of the vehicle speed and the braking force, the higher the vehicle speed, the smaller the regenerative braking force. This phenomenon is shown by the regenerative braking force upper limit line L4 in FIG.

On the other hand, according to the third term on the right side of the equation (2), an engine braking force equivalent to that of the torque converter vehicle, that is, a regenerative braking force can be obtained by setting α according to the speed stage. For example, as shown by the straight lines L1 to L3 in FIG. 7A, α is set so that the regenerative braking force corresponding to the vehicle speed increases as the speed stage increases. However, as described above, in the present invention, when the engine is operated in the high rotation mode during the regenerative travel, the regenerative braking force is increased as the engine speed is higher, that is, the vehicle speed is faster, according to the equation (6). Get smaller. For this reason, as shown in FIG. 7B, the regenerative braking force set by the equation (2) cannot be obtained in the region where the line segments L1 to L3 of the respective speed stages exceed the regenerative braking force upper limit line L4. . Therefore, in the present invention, in the region above the regenerative braking force upper limit line L4, a hydraulic brake is used together to obtain an engine brake equivalent to that of a torque converter vehicle.

-Brake control unit 190-
A brake control signal _{Vbrk_t} is calculated from the braking torque command T _{rq_brk_t} calculated by the traveling motor / brake control unit 180 using the following equation (14).
_{_{_{V brk_t = K brk T rq_brk_t ...}}} (14)
However, K _brk is preset proportional constant as the actual braking torque of the braking torque command T _{Rq_brk_t} and hydraulic brakes are matched.
The hydraulic

brake control valves

35a and 35b are driven based on the brake control signal _{Vbrk_t} , and the

hydraulic brakes

36a and 36b brake the wheels 18. This is the mechanical braking force during regenerative coordination.

-Processing of main controller 100-
Hereinafter, processing performed by the main controller 100 will be described in detail. The following description is divided into a case where the hybrid work vehicle 200 is in a power running operation and a case in which a regenerative operation is being performed.
-For power running-
The travel motor torque command T _{rq_mot_t} output from the travel motor / brake control unit 180 during the power running operation will be described. As described above, the traveling motor torque command T _{rq_mot_t} is calculated from the equation (12). During the power running operation, the travel motor / brake control unit 180 outputs the travel request torque T _{rq_drv_req} as the travel motor torque command T _{rq_mot_t} . The

travel inverters

8F and 8R are driven by the travel request torque command _{Trq_drv_req} , and the

travel motors

7F and 7R output the requested torque.

As described above, the output management unit 140 of the main controller 100 determines that the hybrid work vehicle 200 is in a power running operation when the travel request output P _{wr_drv_req} calculated by the travel request calculation unit 130 is 0 or more. Then, the main controller 100 calculates a power generation output command P _{wr_gen_t} by the equation (8) and an engine output command P _{wr_eng_t} by the equation (9) in order to supply the necessary electric power to the traveling

motors

7F and 7R. Motor generator 6 by the power generation output command _{P Wr_gen_t} is driven, the engine is driven and controlled by the engine output command _{P wr_eng_t.}

The traveling motor / brake control unit 180 calculates the braking torque command T _{rq_brk_t} by the above-described equation (13). As described above, during the power running operation, the braking torque command T _{rq_brk_t} calculated from the equation (13) is zero.

-For regenerative operation-
A travel motor torque command T _{rq_mot_t} output from the travel motor / brake control unit 180 during regeneration will be described. As described above, the traveling motor torque command T _{rq_mot_t} is calculated from the equation (12). During regeneration, the travel request torque T _{rq_drv_req} is negative, and the regeneration power reduction command dP _{wr_mot_t} becomes a predetermined value in the high rotation mode. The negative value of the value obtained by subtracting the regenerative power reduction torque obtained by dividing the regenerative power reduction command dP _{wr_mot_t} by the absolute value of the travel motor rotational speed N _mot from the absolute value | T _{rq_drv_req} | The command becomes T _{rq_mot_t} . This is the regenerative braking torque. The

inverters

8F and 8R are driven based on the regenerative braking torque command, take out the regenerative power from the traveling

motors

7F and 7R, and drive-control the generator motor 5 by the generator inverter 6.

As described above, the output management unit 140 of the main controller 100 determines that the hybrid work vehicle 200 is in a regenerative operation when the travel request output P _{wr_drv_req} calculated by the travel request calculation unit 130 is negative. In this case, the output management unit 140 of the main controller 100 distributes the regenerative power generated by the traveling

motors

7F and 7R to the capacitor 3 and the generator motor 5 by using the power generation output command P _{wr_gen_t} , (9 ) To _calculate engine output command P _{wr_eng_t} , tilt angle increase command dD _{pmp_t} from equation (5), and regenerative power reduction command value dP _{wr_mot_t} from equation (6). Motor generator 6 by the power generation output command _{P Wr_gen_t} is driven, the engine is driven and controlled by the engine output command _{P wr_eng_t.} The pump regulator is driven and controlled by the tilt angle increase command dD _{pmp_t} .

The output management unit 140 of the main controller 100 determines that the capacitor 3 can be charged when the surplus power P _{wr_sup} calculated using the above-described equation (4) is zero. Then, during regenerative operation, the generator motor controller 160 calculates the generator motor torque command T _{rq_gen_t} according to the equation (10). That is, the generator motor torque command T _{rq_gen_t} during regenerative operation is obtained by dividing the power generation output command P _{wr_gen_t} by the engine speed N _eng from the torque obtained by multiplying the difference between the engine speed command and the actual engine speed by a constant. The value obtained by subtracting the torque obtained in this way. The main controller 100 drives the generator inverter 6 by the generator motor torque command T _{rq_gen_t} calculated by the equation (10), and the generator motor 5 consumes the regenerative power in the motor mode by the regenerative power.

The output management unit 140 determines that the capacitor 3 cannot be charged when the surplus power P _{wr_sup} calculated during the regenerative operation is other than zero. In this case, the output management unit 140 determines whether the engine 1 is in the low rotation mode, the rotation suppression mode, or the high rotation mode, and then the power consumption P that is the power to be consumed by the generator motor 5 in the surplus power P _{wr_sup.} _{wr_cns} is calculated. The power consumption _{Pwr_cns in} each mode is as follows.

--- Low rotation mode ---
When the engine 1 is in the low rotation mode, that is, when the rotation speed N _eng of the engine 1 is _{equal to} or less than the first setting threshold N _{eng —} _th1 , the output management unit 140 uses the surplus power P _{wr_sup} and the regenerative power reduction command value dP _{wr_mot_t.} Thus, the power consumption P _{wr_cns} is calculated from the above equation (7). As described above, when the engine 1 is in the low rotation mode, the output management unit 140 sets the regenerative power reduction command value dP _{wr_mot_t} to 0. Therefore, in the low rotation mode, the surplus power P _{wr_sup} is the power consumption. _{Pwr_cns} .

--Rotation suppression mode--
When the engine 1 is in the rotation suppression mode, the output management unit 140 performs the tilt angle increasing process if none of the steering cylinder 12, the lift cylinder 13 and the bucket cylinder 14 is in operation, and then the above equation (7) The power consumption P _{wr_cns} is calculated from the above. In the tilting angle increases processing, output management unit 140 calculates the engine speed _{N eng,} using the first set threshold value _{N Eng_th1,} the tilt angle increase instruction _{dD Pmp_t} by the above equation (5). And the output management part 140 calculates power consumption _{Pwr_cns} from said (7) Formula similarly to the case of the low rotation mode. As described above, when the engine 1 is in the rotation suppression mode, the output management unit 140 sets the regenerative power reduction command value dP _{wr_mot_t} to 0. Therefore, even in the rotation suppression mode, the surplus power P _{wr_sup} is the power consumption. _{Pwr_cns} .

--High speed mode--
When the engine 1 is in the high rotation mode, the output management unit 140 calculates the power consumption P _{wr_cns} from the above equation (7) after performing the regenerative power reduction process. In the regenerative power reduction process, the output management unit 140 calculates the regenerative power reduction command value dP _{wr_mot_t} according to the above equation (6) using the engine speed N _eng and the second set threshold value N _{eng_th2} . Even in the high rotation mode, the output management unit 140 performs the tilt angle increasing process as in the rotation suppression mode if neither the lift cylinder 13 nor the bucket cylinder 14 is in operation.

The brake control unit 190 calculates a brake control signal _{Vbrk_t} using the equation (14) based on the braking torque command T _{rq_brk_t} calculated using the equation (13), and outputs the brake control signal _{Vbrk_t} to the hydraulic brake control valve. Thus, the brake control unit 190 causes the

hydraulic brakes

36a and 36b to generate a braking torque corresponding to the regenerative torque of the traveling

motors

7F and 7R that is reduced by the regenerative power reduction command dP _{wt_mot_t} .

As described above, when the power consumption P _{wr_cns} is calculated in any one of the low rotation mode, the rotation suppression mode, and the high rotation mode, the output management unit 140 uses the above equation (8) to generate the power generation output command P _{wr_gen_t.} Is calculated. The generator motor control unit 160 uses the engine speed N _eng , the power generation output command P _{wr_gen_t} calculated by the output management unit 140, and the engine speed command N _{eng_t} according to the above equation (10). The command T _{rq_gen_t} is calculated. Then, the generator motor controller 160 controls the generator motor 5 by transmitting the calculated generator motor torque command T _{rq_gen_t} to the generator inverter 6. As a result, the generator motor 5 is driven by a torque value obtained by appropriately reducing the torque generated by surplus power.

When the power generation output command P _{wr_gen_t} is calculated, the output management unit 140 uses the hydraulic pressure request output P _{wr_pmp_req} from the hydraulic pressure request calculation unit 120 and the power generation output command P _{wr_gen_t} to output the engine according to the above equation (9). The command P _{wr_eng_t} is calculated. Based on the engine output command P _{wr_eng_t} calculated by the output management unit 140, the target speed calculation unit 150 calculates the engine speed command N _{eng_t} using the engine fuel efficiency map as described above, and the engine controller Output to 2. When the engine controller 2 receives the engine speed command N _{eng — t} from the target speed calculator 150, the engine controller 2 rotates the engine 1 at the engine speed indicated by the engine speed command.

Hybrid work vehicle 200 in the present embodiment, when neither the accelerator pedal nor the brake pedal is depressed, according to the speed stage set by the operator and the traveling motor rotation speed N _mot corresponding to the traveling speed of the vehicle, The amount of braking is controlled by the traveling

motors

7F and 7R and the

hydraulic brakes

36a and 36b.
FIG. 7 shows the relationship between the braking force for each speed stage and the traveling speed of the vehicle. In FIG. 7, the solid line L1 indicates the first speed, the broken line L2 indicates the second speed, and the alternate long and short dash line L3 indicates the third speed. FIG. 7A shows the relationship between the traveling speed for each speed stage and the required regenerative braking force. As shown in the figure, the smaller the speed stage is set, the greater the required regenerative braking force with increasing travel speed.

However, the regenerative braking force by the traveling

motors

7F and 7R has an upper limit due to the above equation (6). In FIG. 7 (b), this upper limit is indicated by a two-dot chain line L4. As indicated by L4, the regenerative braking force gradually decreases as the traveling speed of the vehicle increases. As shown in FIG. 7B, in the case of the first speed, the regenerative braking force increases along L1 until the traveling speed reaches V1, and when the traveling speed exceeds V1, the regenerative braking force follows L4. Gradually decrease. For this reason, when the traveling speed exceeds V1, the required regenerative braking force cannot be obtained with the regenerative braking force by the traveling

motors

7F and 7R. Even in the case of the second speed and the third speed, if the traveling speed exceeds V2 and V3, respectively, the regenerative braking force gradually decreases along L4, so that the required required regenerative braking force cannot be obtained. In the following description, the traveling speeds V1, V2, and V3 are referred to as upper limit speeds.

In the present embodiment, as described above, when the regenerative braking force by the traveling

motors

7F and 7R cannot obtain the required regenerative braking force, the insufficient braking force is compensated by the braking force by the

hydraulic brakes

36a and 36b. FIG. 7C shows that the required regenerative braking force is B1a exceeding the regenerative braking force B1 if the traveling speed is V1a (> V1) in the first speed. In this case, the brake control unit 190 calculates the brake control signal _{Vbrk_t} so that the

hydraulic brakes

36a and 36b generate a braking force corresponding to the difference between the required regenerative braking force B1a and the regenerative braking force B1.

The characteristics L1 to L3 of the regenerative braking force with respect to the vehicle speed as described above are set for each speed stage, but this is realized by setting α in equation (2) according to the speed stage. Further, the hydraulic braking force with respect to the vehicle speed in the region above the upper limit line L4 of the regenerative braking force can be realized by equations (12) to (14). That is, in the output management unit 140, the required travel torque T _{rq_drv_req} calculated from the expression (2), the traveling motor rotation speed N _mot from the rotation speed sensor 22, and the regenerative power reduction command dP calculated from the expression (6). _{Using wr_mot_t} , a traveling motor torque command T _{rq_mot_t} is calculated from the equation (12). Further, the traveling motor / brake control unit 180 uses the traveling motor torque command T _{rq_mot_t} calculated from the equation (12), the required traveling torque T _{rq_drv_req} calculated from the equation (2), and the traveling motor rotation speed N _mot. The braking torque command T _{rq_brk_t} is calculated by the above equation (13).

In addition, although the coefficient α in the equation (2) has been explained that a larger value is set as the speed stage is smaller. The ratio of the magnitude of α corresponds to the slopes L1 to L3 in FIG.

The processing by the main controller 100 will be described using the flowchart shown in FIG. The processing in FIG. 8 is performed by executing a program on the main controller 100. This program is stored in a memory (not shown). When an ignition switch (not shown) of the hybrid work vehicle 200 is turned on, the program is started and executed by the main controller 100.

In step S1A, the speed stage selected by the shift switch 40 is read, a constant corresponding to the speed stage is set in the coefficient α used in equation (2), and the process proceeds to step S1. The coefficient α is larger as the speed stage is smaller. In step S1, it is determined whether or not the traveling

motors

7F and 7R are in a regenerative operation. If the travel request output P _{wr_drv_req} calculated by the travel request calculation unit 130 is 0 or more, that is, if the

travel motors

7F and 7R are in power running, step S1 is affirmed and the process proceeds to step S2. In step S2, running motor drive control is performed, and the process ends. In this case, the output management unit 140 of the main controller 100 calculates a power generation output command and an engine output command in order to supply necessary electric power to the traveling

motors

7F and 7R. A torque command and an engine speed command are output to the engine 1 to control driving of the generator motor 5 and the engine 1.

When the travel request output P _{wr_drv_req} calculated by the travel request calculation unit 130 is less than 0, that is, when the

travel motors

7F and 7R are in the regenerative operation, a negative determination is made in step S1 and the process proceeds to step S3. In step S3, it is determined whether sufficient regenerative power can be obtained by charging. If sufficient regenerative power is obtained by charging, that is, if the surplus power P _{wr_sup} is 0, an affirmative determination is made in step S3 and the process proceeds to step S9A described later. If sufficient regenerative power cannot be obtained by charging, that is, if the surplus power P _{wr_sup} is a positive or negative value, a negative determination is made in step S3 and the process proceeds to step S4.

In step S4, it is determined whether or not the engine 1 is in the low rotation mode. When the engine 1 is in the low rotation mode, that is, when the engine speed N _eng is _{equal to} or lower than the first set threshold value N _{eng —} _th1 , step S4 is affirmed and the process proceeds to step S9 described later. If the engine 1 is not in the low speed mode, a negative determination is made in step S4 and the process proceeds to step S5.

In step S5, it is determined whether any one of the lift cylinder 13 and the bucket cylinder 14 is operating. If the lift cylinder 13 and the bucket cylinder 14 are not operating, a negative determination is made in step S5 and the process proceeds to step S6. In step S6, the tilt angle increasing process described above is performed, and the process proceeds to step S7.

When either the lift cylinder 13 or the bucket cylinder 14 is operating, an affirmative determination is made in step S5 and the process proceeds to step S7. In step S7, it is determined whether or not the engine 1 is in the rotation suppression mode. If the engine 1 is rotated suppression mode, i.e. when the rotation speed _{N eng} of the engine 1 is in the second set threshold value _{N Eng_th2} less larger than the first set threshold value _{N Eng_th1} proceeds step S7 is affirmative decision to step S9. If the engine 1 is in the high speed mode, that is, if the engine speed N _eng is _{equal to} or greater than the second set threshold value N _{eng —} _th2 , step S7 is negatively determined and the process proceeds to step S8.

In step S8, a regenerative electric power reduction process is performed and it progresses to step S9. In step S9, power consumption _{Pwr_cns} consumed in the generator motor 5 is calculated from the surplus power _{Pwr_sup, and} the process proceeds to step S9A. In step S9A, charge control is performed and the process proceeds to step S10. In step S10, the generator motor 5 is controlled, and the process proceeds to step S11. In this case, the generator motor control unit 160 uses the engine speed N _eng , the power generation output command P _{wr_gen_t} calculated by the output management unit 140 using the above equation (8), and the engine speed command N _{eng_t.} Then, the generator motor torque command T _{rq_gen_t} is calculated using the equation (10). Then, the generator motor controller 160 controls the generator motor 5 by transmitting the calculated generator motor torque command T _{rq_gen_t} to the generator inverter 6.

In step S11, the rotational speed of the engine 1 is controlled via the engine controller 2, and the process proceeds to step S13. In this case, the target engine speed calculation unit 150 calculates the engine speed command N _{eng_t} using the engine fuel consumption map, as described above, based on the engine output command P _{wr_eng_t} calculated by the output management unit 140. To the engine controller 2. As a result, the engine 1 rotates at the engine speed indicated by the calculated engine speed command _{Neng_t} .

Progressing to step S13 following step S11, hydraulic brake control processing is executed. In step S13, the brake control signal _{Vbrk_t} is calculated using the above-described equation (14), is output to the hydraulic brake control valve, the

hydraulic brakes

36a and 36b are driven, and the process ends.

The effects of the hybrid work vehicle according to the first embodiment described above will be described.
(1) The hybrid work vehicle according to the first embodiment is charged by the traveling

motors

7F and 7R that apply traveling driving torque to the wheels 18a to 18d, and the regenerative electric power generated by the traveling

motors

7F and 7R. The power storage device that supplies driving power to 7R, that is, the capacitor 3, and the power generation mode are driven by the engine 1 in the power generation mode, and the power generation is driven by the regenerative power from the traveling

motors

7F and 7R in the electric mode. A motor 5, a hydraulic pump 9 that is mechanically connected to and driven by the generator motor 5 and the engine 1 and supplies pressure oil to the hydraulic actuators 12 to 14, and a speed stage setting device that sets one of a plurality of speed stages That is, a control device that drives and controls the cyst switch 40, the traveling

motors

7F and 7R, and the generator motor 5, that is, a main controller. And a 100. Based on the characteristics of the drive torque with respect to the number of revolutions set for each speed stage, the control device 100 performs power running control by calculating a larger travel drive torque as the set speed stage is larger, and is set for each speed stage. Based on the characteristics of the regenerative braking force with respect to the vehicle speed, the regenerative control is performed by calculating a larger regenerative braking force as the set speed stage is smaller.
Therefore, a sufficient regenerative braking force that matches the speed stage is obtained as in the conventional torque converter vehicle.

(2) When the main controller 100 determines that the required regenerative braking force exceeds the limit of regenerative braking by the traveling

motors

7F and 7R, the main controller 100 activates the

hydraulic brakes

36a and 36b that apply braking force to the wheels, and during regenerative braking Necessary braking force was obtained at each speed stage. Therefore, even if it is a hybrid work vehicle that obtains a large regenerative braking force as the speed stage is small and does not obtain a regenerative braking force required at high speed traveling as a result of performing regenerative power limitation at high speed, Sufficient braking force can be obtained at high speeds at each speed stage.

(3) In the hybrid work vehicle of the first embodiment, the upper limit value of the regenerative braking force becomes smaller as the vehicle speed increases, and the regenerative braking force calculated by the main controller 100 in the regenerative control exceeds the upper limit value. When this is the case, the braking force that is insufficient by the hydraulic

brake control valves

35a and 35b that apply frictional braking force to the wheels is added. Therefore, even if the regenerative power is limited in a driving state where the vehicle speed is high such that the engine 1 is driven in the high rotation mode, a shortage of the regenerative braking force can be obtained by the mechanical brake.
(4) For example, in the hybrid work vehicle according to the first embodiment, the upper limit value of the regenerative braking force is defined by a decrease in the regenerative braking force that increases as the vehicle speed increases. A braking force can be obtained.
(5) For example, in the hybrid work vehicle of the first embodiment, when the regenerative power is larger than the power that can be charged in the capacitor 3 in the region where the rotational speed of the generator motor 5 is higher than a predetermined value, the surplus The generator motor 5 is controlled so that electric power is consumed by the generator motor 5. In addition, the amount of regenerative power consumed by the generator motor 5 is reduced according to the amount of deviation between the rotational speed of the generator motor 5 and the predetermined value. In this case, the main controller 100 applies a mechanical brake corresponding to the reduction amount of the regenerative power to the wheels.

-Second Embodiment-
A second embodiment of a hybrid work vehicle according to the present invention will be described with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and different points will be mainly described. Points that are not particularly described are the same as those in the first embodiment. This embodiment is different from the first embodiment in that the number of rotations of the cooling fan provided in the hydraulic circuit is further controlled according to the required regenerative braking force.

FIG. 9 is a circuit diagram showing a hydraulic circuit HC included in the hybrid work vehicle 200 according to the present embodiment. The hydraulic circuit HC includes a variable displacement hydraulic pump 9, an oil tank 10, a control valve 11, a variable displacement motor hydraulic pump 301, a first proportional valve 302, a second proportional valve 303, A hydraulic motor 304, a cooling fan 305, a cooling core 306, a temperature sensor 307, and a relief valve 310 are provided. The hydraulic pump 9, the relief valve 310, and the control valve 11 are connected to the first pipeline 400 in this order with the oil tank 10 as the upstream side. A hydraulic pump for motor 301, a hydraulic motor 304, and a cooling core 306 are connected to the second pipe line 401 in this order with the oil tank 10 at the upstream side.

As described above, the hydraulic pump 9 is driven by the engine 1 to supply the hydraulic oil in the oil tank 10 to the steering cylinder 12, the lift cylinder 13 and the bucket cylinder 14 via the control valve 11. The first proportional valve 302 controls the tilt amount (capacity) of the first hydraulic pump 9 to be changeable in accordance with a control signal from the main controller 100. When the pressure in the first pipe line 400 becomes high, the relief valve 310 protects the circuit by releasing part or all of the hydraulic oil to the return side and keeping the circuit pressure constant. The control valve 11 includes a first directional control valve 308 and a second directional control valve 309. The first directional control valve 308 supplies hydraulic oil supplied from the first hydraulic pump 9 to the steering cylinder 12 in response to a signal output from the operating device 31 installed in the cab 19. The second direction control valve 309 supplies hydraulic oil supplied from the hydraulic pump 9 to the pair of lift cylinders 13 in response to a signal output from the operation device 31 installed in the cab 19. The bucket cylinder 14 is not shown.

The rotating shaft of the motor hydraulic pump 301 is provided coaxially with the drive shaft of the engine 1. When the motor hydraulic pump 301 is driven by the engine 1, the hydraulic oil in the oil tank 10 is supplied to the hydraulic motor 304 to drive the hydraulic motor 304. The second proportional valve 303 controls the tilt amount (capacity) of the motor hydraulic pump 301 so as to be changeable in accordance with a control signal from the main controller 100. The tilt amount of the motor hydraulic pump 301 is controlled based on the temperature of the hydraulic oil in the oil tank 10 detected by the temperature sensor 307. The cooling fan 305 is driven by a hydraulic motor 304 and cools the hydraulic oil flowing into the cooling core 306 provided downstream of the cooling fan 305. For this reason, the rotation speed of the cooling fan 305 is controlled according to the amount of tilt of the second hydraulic pump 301. In other words, the rotation speed of the cooling fan 305 is controlled according to the temperature of the hydraulic oil detected by the temperature sensor 307.

FIG. 10 is a diagram showing the relationship between the number of rotations of the cooling fan 305 and the temperature of the hydraulic oil detected by the temperature sensor 307. As shown in FIG. 10, when the temperature of the hydraulic oil is lower than a predetermined temperature t1, the rotation speed of the cooling fan 305 is controlled to be a specified minimum rotation speed Min. When the temperature of the hydraulic oil is equal to or higher than the predetermined temperature t1, the rotation speed of the cooling fan 305 is controlled to increase in proportion to the increase in the temperature of the hydraulic oil. When the temperature of the hydraulic oil becomes equal to or higher than a predetermined temperature t2 (> t1), the cooling fan 305 is controlled so as to have a specified maximum rotational speed Max.

(Increase the rotation speed of the hydraulic motor 304)
When the capacitor 3 is fully charged during the regenerative operation and cannot be further charged, the regenerative power is consumed by driving the generator motor 5 with the power generated by the traveling

motors

7F and 7R. In the hybrid work vehicle according to the present invention, the amount of tilt of the cooling motor hydraulic pump 301 is increased during the regenerative operation to increase the pump absorption horsepower, thereby increasing the load on the generator motor 5. As a result, the regenerative power consumed by the generator motor 5 can be increased, and the regenerative braking force can be increased.

When the output controller 140 determines that the capacitor 3 cannot be charged when the surplus power P _{wr_sup} calculated during the regenerative operation is other than 0, the main controller 100 calculates the travel calculated by the above equation (2). It is determined whether the required torque T _{rq_drv_req} , that is, the required regenerative braking force exceeds a predetermined threshold value T _{rq_drv_th1} . When the required regenerative braking force is _{equal to} or greater than the threshold value T _{rq_drv_th1} , the main controller 100 sets the motor hydraulic pump 304 so that the cooling fan 305 has the maximum rotation speed Max regardless of the temperature of the hydraulic oil detected by the temperature sensor 307. Control the amount of tilt (capacity). When the required regenerative braking force is less than the threshold value T _{rq_drv_th1} , as described above, the main controller 100 controls the rotational speed of the cooling fan 305 according to the temperature of the hydraulic oil detected by the temperature sensor 307. The amount of tilt of the cooling motor hydraulic pump 301 is controlled.

The threshold value T _{rq_drv_th1} is set as a value of the regenerative braking force corresponding to the maximum absorption horsepower of the generator motor 5, and is stored in advance in a memory (not shown) or the like. That is, when the regenerative power from the traveling

motors

7F and 7R exceeds the maximum power consumption of the generator motor 5, the amount of regenerative power consumption is increased by increasing the tilt amount of the cooling motor hydraulic pump 301.

FIG. 11 shows the number of rotations of the cooling fan 305 controlled as described above according to the temperature of the hydraulic oil and the required regenerative braking force. As shown in the figure, when the required regenerative braking force is _greater than or equal to the threshold value T _{rq_drv_th1} , the cooling fan 305 is controlled so as to be driven at the maximum rotational speed Max regardless of the detected temperature of the hydraulic oil. On the other hand, when the required regenerative braking force is less than the threshold value T _{rq_drv_th1} , or when the required regenerative braking force is 0, the cooling fan is proportional to the detected temperature increase of the hydraulic oil as shown in FIG. The number of rotations of 305 is controlled to increase.

As a result, when the output controller 140 determines that the capacitor 3 cannot be charged when the surplus power P _{wr_sup} calculated during the regenerative operation is other than 0, the main controller 100 controls the hydraulic pump 301 for the cooling motor. Increase hydraulic load. As a result, the load on the generator motor 5 driven by surplus power is increased, and the braking force during regeneration can be increased.

The processing by the main controller 100 will be described using the flowchart shown in FIG. The processing in FIG. 12 is performed by executing a program on the main controller 100. This program is stored in a memory (not shown). When an ignition switch (not shown) of the hybrid work vehicle 200 is turned on, the program is started and executed by the main controller 100.

Each process from step S21A (α setting) to step S29 (power consumption calculation) is the same as each process from step S1A (α setting) to step S9 (power consumption calculation) in FIG. In step S30, it is determined whether or not the required regenerative braking force exceeds a threshold th1 based on the power consumption _{Pwr_cns} and the regenerative braking force when the cooling fan 305 is driven at the maximum rotation speed Max. If the requested regenerative braking force is _greater than or equal to the threshold value T _{rq_drv_th1} , an affirmative determination is made in step S30 and the process proceeds to step S31. In step S31, the amount of tilt of the second hydraulic pump 304 is controlled to drive the cooling fan 305 at the maximum rotation speed Max, and the process proceeds to step S29A. If the requested regenerative braking force is less than the threshold value T _{rq_drv_th1} , a negative determination is made in step S30, and the process proceeds to step S32. In step S32, the tilt amount of the second hydraulic pump is controlled in accordance with the temperature of the hydraulic oil detected by the temperature sensor 307, the cooling fan 305 is driven, and the process proceeds to step S29A. Each process from step S29A (charge control) to step S36 (hydraulic brake drive) is the same as each process from step S9A (charge control) to step S13 (hydraulic brake drive) in FIG.

According to the hybrid work vehicle according to the second embodiment described above, the following operational effects can be obtained.
The main controller 100 controls the flow rate of the pressure oil discharged from the second hydraulic pump 301 based on the pressure oil temperature and the required regenerative braking force. Therefore, when the regenerative power exceeds the maximum power consumption of the generator motor 5, the amount of tilt of the cooling motor hydraulic pump 301 is increased to increase the pump load. Therefore, the load on the generator motor 5 driven by surplus power is increased, and the braking force during regeneration can be increased. Furthermore, since an increase in braking force during regeneration can be realized using an existing configuration, an increase in manufacturing cost can be reduced.

The hybrid work vehicle 200 of the first and second embodiments described above can be modified as follows.
(1) In the work vehicle 200 of the embodiment, a pair of

travel motors

7F and 7R are used, but a work vehicle using one travel motor may be used.
(2) In the main controller 100 of the embodiment, the engine 1, the generator motor 5, the traveling

motors

7F and 7R, the brake valve 35b, and the like are driven and controlled by the equations (1) to (14). It is an example. It is also possible to employ a main controller designed to drive and control similar devices using different mathematical formulas.

(3) The work vehicle of the embodiment has set the first to third speed stages, but may be a work vehicle having first and second speed stages, and may have four or more speed stages. Good.
(4) Instead of using a series hybrid system in which the wheels 18 are driven by the generator motor 5 driven by the engine 1, travel driving force is obtained by the engine 1, and electric power generated by the generator motor 5 driven by the engine 1 is used. You may use the parallel hybrid type which obtained the driving motor driven.

(5) Although the work vehicle of the embodiment has been described with the wheel loader, the vehicle is charged with a traveling motor that applies traveling driving torque to the wheels, a control device that performs power running control and regenerative control of the traveling motor, and regenerative power generated by the traveling motor. And a power storage device that supplies driving power to the traveling motor, and in the power generation mode, the power is driven by the engine to generate electric power, and in the electric mode, the generator motor that is driven by regenerative power, the generator motor, and the engine A hydraulic pump that is mechanically connected and driven to supply pressure oil to the hydraulic actuator and a speed stage setting device that sets a plurality of speed stages are provided. The control device determines the characteristics of the regenerative braking force with respect to the vehicle speed. Each type has a different regenerative braking force when the accelerator pedal is not depressed and the set speed stage is smaller. The present invention can be applied to a hybrid working vehicle.

As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

The disclosure of the following priority application is hereby incorporated by reference.
Japanese Patent Application 2013-265719 (filed on December 24, 2013)

1 ... Engine, 3 ... Power storage device,
5 ... generator motor, 7F, 7R ... traveling motor,
9 ... hydraulic pump, 12 ... steering cylinder,
13 ... lift cylinder, 14 ... bucket cylinder,
DESCRIPTION OF SYMBOLS 21 ... Vehicle speed sensor, 22 ... Traveling motor rotation speed sensor 31 ... Operating device, 40 ... Shift switch 35a ... Brake device, 36b ... Brake valve 100 ... Main controller, 110 ... Power storage management part,
120 ... Hydraulic pressure request calculation unit, 130 ... Travel request calculation unit,
140 ... output management unit, 150 ... target rotational speed calculation unit,
160 ... generator motor control unit, 170 ... tilt angle control unit,
180: traveling motor / brake control unit, 200 ... hybrid work vehicle,
301 ... Hydraulic pump for motor, 304 ... Hydraulic motor,
305 ... Cooling fan, 307 ... Temperature sensor

Claims

A traveling motor (7F, 7R) that applies traveling driving torque to the wheels;
A power storage device (3) that is charged by regenerative power generated by the traveling motor and supplies driving power to the traveling motor;
During the power generation mode, the generator is driven by the engine to generate power, and during the power running mode, the generator motor (5) driven by the regenerative power from the traveling motor;
A hydraulic pump (9) that is mechanically connected to and driven by the generator motor and the engine and supplies pressure oil to a hydraulic actuator;
A speed stage setting device (40) for setting any one of a plurality of speed stages;
A control device (100) for driving and controlling the traveling motor and the generator motor,
The control device is configured such that the set speed stage is small based on the characteristics of the driving torque with respect to the rotational speed set for each speed stage and the characteristics of the regenerative braking force with respect to the vehicle speed set for each speed stage. A hybrid work vehicle having a drive control unit (130) that performs regenerative control by calculating a large regenerative braking force.
The hybrid work vehicle according to claim 1,
A braking device (36a, 36b) for applying a frictional braking force to the wheel;
When the regenerative braking force calculated in the regenerative control exceeds an upper limit set so that the regenerative braking force is smaller as the vehicle speed is faster, the control device adds a deficient braking force. A hybrid work vehicle further including a braking control unit (180) for controlling the motor.
The hybrid work vehicle according to claim 2,
The control device further includes a charge control unit (140) that performs regenerative power restriction control that restricts regenerative power charged in the power storage device according to the rotation speed when the rotation speed of the generator motor is equal to or greater than a predetermined value. Have
The hybrid work vehicle wherein the upper limit value of the regenerative braking force is determined by the regenerative power limit control.
The hybrid work vehicle according to claim 2,
In the region where the rotational speed of the generator motor is higher than a predetermined value, the control device causes the surplus power to be consumed by the generator motor when the regenerative power is larger than the power that can be charged to the power storage device. The power generation control unit (160) that controls the generator motor and controls the reduction of the regenerative electric power consumed by the generator motor as the deviation amount increases according to the deviation amount between the rotation speed and the predetermined value. )
The brake control unit is a hybrid work vehicle that performs control to apply a frictional braking force corresponding to a reduction amount of the regenerative power to the wheels.
The hybrid work vehicle according to claim 2,
The controller is
A travel request based on the accelerator required torque calculated based on the accelerator pedal depression amount and the vehicle speed, the regenerative braking torque calculated based on the brake pedal depression amount, and the regenerative braking torque calculated based on the speed stage Calculate the torque,
In a region where the rotational speed of the generator motor is higher than a predetermined value, according to the amount of deviation between the rotational speed and the predetermined value, a reduction amount of regenerative power consumed by the generator motor is calculated,
Calculate a regenerative reduction torque obtained by converting the reduction amount of the regenerative power by the number of revolutions of the travel motor, subtract the calculated regenerative reduction torque from the travel request torque to calculate a travel motor torque command,
Subtract the travel motor torque command from the travel request torque to calculate the insufficient braking torque,
Calculating a braking signal to which the braking device adds the insufficient braking force;
The braking control device is a hybrid work vehicle that drives and controls the braking device according to the braking signal.
The hybrid work vehicle according to claim 3, wherein
In the region where the rotational speed of the generator motor is higher than a predetermined value, the control device causes the surplus power to be consumed by the generator motor when the regenerative power is larger than the power that can be charged to the power storage device. The power generation control unit (160) that controls the generator motor and controls the reduction of the regenerative electric power consumed by the generator motor as the deviation amount increases according to the deviation amount between the rotation speed and the predetermined value. )
The brake control unit is a hybrid work vehicle that performs control to apply a frictional braking force corresponding to a reduction amount of the regenerative power to the wheels.
The hybrid work vehicle according to claim 3, wherein
The controller is
A travel request based on the accelerator required torque calculated based on the accelerator pedal depression amount and the vehicle speed, the regenerative braking torque calculated based on the brake pedal depression amount, and the regenerative braking torque calculated based on the speed stage Calculate the torque,
In a region where the rotational speed of the generator motor is higher than a predetermined value, according to the amount of deviation between the rotational speed and the predetermined value, a reduction amount of regenerative power consumed by the generator motor is calculated,
Calculate a regenerative reduction torque obtained by converting the reduction amount of the regenerative power by the number of revolutions of the travel motor, subtract the calculated regenerative reduction torque from the travel request torque to calculate a travel motor torque command,
Subtract the travel motor torque command from the travel request torque to calculate the insufficient braking torque,
Calculating a braking signal to which the braking device adds the insufficient braking force;
The braking control device is a hybrid work vehicle that drives and controls the braking device according to the braking signal.
The hybrid work vehicle according to claim 4,
The controller is
A travel request based on the accelerator required torque calculated based on the accelerator pedal depression amount and the vehicle speed, the regenerative braking torque calculated based on the brake pedal depression amount, and the regenerative braking torque calculated based on the speed stage Calculate the torque,
In a region where the rotational speed of the generator motor is higher than a predetermined value, according to the amount of deviation between the rotational speed and the predetermined value, a reduction amount of regenerative power consumed by the generator motor is calculated,
Calculate a regenerative reduction torque obtained by converting the reduction amount of the regenerative power by the number of revolutions of the travel motor, subtract the calculated regenerative reduction torque from the travel request torque to calculate a travel motor torque command,
Subtract the travel motor torque command from the travel request torque to calculate the insufficient braking torque,
Calculating a braking signal to which the braking device adds the insufficient braking force;
The braking control device is a hybrid work vehicle that drives and controls the braking device according to the braking signal.
The hybrid work vehicle according to claim 6, wherein
The controller is
A travel request based on the accelerator required torque calculated based on the accelerator pedal depression amount and the vehicle speed, the regenerative braking torque calculated based on the brake pedal depression amount, and the regenerative braking torque calculated based on the speed stage Calculate the torque,
In a region where the rotational speed of the generator motor is higher than a predetermined value, according to the amount of deviation between the rotational speed and the predetermined value, a reduction amount of regenerative power consumed by the generator motor is calculated,
Calculate a regenerative reduction torque obtained by converting the reduction amount of the regenerative power by the number of revolutions of the travel motor, subtract the calculated regenerative reduction torque from the travel request torque to calculate a travel motor torque command,
Subtract the travel motor torque command from the travel request torque to calculate the insufficient braking torque,
Calculating a braking signal to which the braking device adds the insufficient braking force;
The braking control device is a hybrid work vehicle that drives and controls the braking device according to the braking signal.