JP2017053212A - Work vehicle and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hybrid type work vehicle that secures operations of both hydraulic equipment and electric equipment as efficiently as possible although lowering output of an engine when the storage amount of a reductant becomes small.SOLUTION: A hydraulic pump is driven by an engine. A hydraulic actuator is driven with hydraulic oil discharged from a hydraulic pump. A generator motor is driven by the engine. An electric actuator is driven with electric power generated by the generator motor. An exhaust processing device purifies exhaust of the engine. A reductant tank reserves a reductant supplied to the exhaust processing device. A storage amount detection part detects the storage amount of the reductant in the reductant tank. An engine control part performs output limitation control to lower the output of the engine when the storage amount becomes equal to or less than a first threshold. An electric actuator control part limits the output of the electric actuator during execution of the output limitation control.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a work vehicle and a control method thereof.

  Some work vehicles include an engine, a hydraulic pump driven by the engine, and a hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump. The hydraulic actuator is a hydraulic cylinder, for example, and drives a working machine having a boom, an arm, and the like. In such a work vehicle, the hydraulic pump is controlled so that the absorption torque of the hydraulic pump does not exceed the output torque of the engine.

  On the other hand, some work vehicles include an exhaust treatment device that purifies engine exhaust using a reducing agent. In such a work vehicle, the reducing agent is stored in the reducing agent tank. However, if the amount of reducing agent stored in the reducing agent tank decreases, there is a possibility that the exhaust treatment may not be performed appropriately. Therefore, for example, in the work vehicle of Patent Document 1, when the amount of reducing agent stored is less than a predetermined amount, control is performed to reduce the output of the engine and the absorption torque of the hydraulic pump. This can prompt the operator to supply the reducing agent.

Japanese Patent Laying-Open No. 2015-71973

  In recent years, a hybrid work vehicle has been developed that includes a generator motor driven by an engine and an electric actuator driven by electric power generated by the generator motor together with a hydraulic pump and a hydraulic actuator. For example, a hybrid hydraulic excavator includes a hydraulic cylinder for driving a work machine and an electric motor for turning a turning body.

  In such a hybrid work vehicle, when control is performed to reduce engine output when the amount of reducing agent stored decreases, the operation of both the hydraulic equipment and the electric equipment should be ensured as efficiently as possible. Is desirable. However, even if the absorption torque of the hydraulic pump is reduced as in the past, even if the operation of the electrical equipment can be easily secured, the output of many engines will be used for the electrical equipment, ensuring the operation of the hydraulic equipment. It is difficult to do.

  It is an object of the present invention to ensure the operation of both hydraulic equipment and electrical equipment as efficiently as possible while reducing the engine output when the amount of reducing agent stored in a hybrid work vehicle decreases. There is to do.

  A work vehicle according to one aspect of the present invention includes an engine, a hydraulic pump, a hydraulic actuator, a generator motor, an electric actuator, an exhaust treatment device, a reducing agent tank, a storage amount detection unit, and an engine control unit. And an actuator control unit. The hydraulic pump is driven by the engine. The hydraulic actuator is driven by hydraulic oil discharged from the hydraulic pump. The generator motor is driven by the engine. The electric actuator is driven by electric power generated by the generator motor. The exhaust treatment device purifies the exhaust of the engine. The reducing agent tank stores the reducing agent supplied to the exhaust treatment device. The storage amount detection unit detects the storage amount of the reducing agent in the reducing agent tank. The engine control unit performs output restriction control for reducing the output of the engine when the storage amount becomes equal to or less than the first threshold value. The electric actuator control unit limits the output of the electric actuator during the execution of the output restriction control.

  In the work vehicle according to this aspect, when the storage amount becomes equal to or less than the first threshold, the output of the engine is reduced and the output of the electric actuator is limited. Therefore, compared with the case where the output of an electric actuator is not restrict | limited, the output of the engine distributed to a hydraulic pump can be ensured largely. Thus, in the hybrid work vehicle, when the amount of reducing agent stored is reduced, the operations of both the hydraulic device and the electric device can be efficiently ensured.

  The work vehicle may further include an output calculation unit, an absorption torque determination unit, and a pump control unit. The output calculation unit may calculate the output of the generator motor necessary for driving the electric actuator when the storage amount becomes equal to or less than the first threshold value. The absorption torque determination unit may determine the absorption torque of the hydraulic pump based on the reduced engine output and the generator motor output necessary for driving the electric actuator. The pump control unit may control the hydraulic pump with the determined absorption torque.

  In this case, when the storage amount becomes equal to or less than the first threshold value, the absorption torque of the hydraulic pump is determined based on the reduced engine output and the generator motor output necessary for driving the electric actuator. . Here, the output torque of the hydraulic pump necessary for driving the hydraulic actuator varies greatly depending on the load applied to the work implement. Therefore, it is not easy to accurately estimate the torque to be distributed to the hydraulic pump in the output restriction control.

  On the other hand, the output of the generator motor necessary for driving the electric actuator can be estimated with higher accuracy than the output torque of the hydraulic pump required for driving the hydraulic actuator. Therefore, first, the output of the generator motor necessary for driving the electric actuator is calculated, and the absorption torque of the hydraulic pump is determined based on the calculation result. The output and the absorption torque of the hydraulic pump can be determined. As a result, in the hybrid work vehicle, when the amount of reducing agent stored is reduced, the operations of both the hydraulic device and the electric device can be ensured as efficiently as possible.

  When the storage amount is less than or equal to the second threshold value that is less than the first threshold value, the electric actuator control unit may stop the electric actuator. In this case, the operator can be urged to supply the reducing agent.

  The work vehicle may further include a power control device that is electrically connected to the generator motor and the electric actuator. When the storage amount is equal to or less than the second threshold and a predetermined system stop condition is satisfied, the electric actuator control unit may stop the power control device. In this case, the operator can be urged to supply the reducing agent.

  The system stop condition may include that the operating speed of the electric actuator has decreased to a predetermined speed. In this case, the electric power control apparatus can be stopped while the electric actuator is stopped or almost stopped. Thereby, it can avoid that a power control apparatus stops during operation | movement of an electric actuator.

  The system stop condition may further include that the torque command value to the generator motor is zero. In this case, it is possible to avoid stopping the power control device during power generation by the generator motor. Thereby, it is possible to prevent the power control device from being damaged by the power generated by the generator motor after the power control device is stopped.

  When the storage amount is equal to or less than the second threshold value, the electric actuator control unit may set the torque command value of the electric actuator to zero. Thereby, the electric actuator can be stopped.

  The engine control unit may control the output of the engine with the first engine torque curve at a normal time when the storage amount is larger than the first threshold. In the output restriction control, the engine control unit may control the output of the engine with a second engine torque curve that defines an engine output lower than the first engine torque curve. In this case, the engine output can be reduced in the output restriction control by changing the engine torque curve.

  The electric actuator control unit may reduce the upper limit of the output torque of the electric actuator in the output restriction control. Thereby, the output of the electric actuator can be reduced in the output restriction control.

  The work vehicle may further include a traveling body and a revolving body supported so as to be able to turn with respect to the traveling body. The electric actuator may be an electric motor that turns the turning body. In this case, the fluctuation of the load applied to the electric motor is small compared to the load applied to the hydraulic actuator. Therefore, the output of the generator motor necessary for driving the electric actuator can be accurately calculated.

  A work vehicle control method according to another aspect of the present invention includes the following steps. In the first step, the amount of reducing agent stored in the reducing agent tank is detected. In the second step, output restriction control is performed to output a signal for reducing the output of the engine when the storage amount becomes equal to or less than the first threshold value. In the third step, a signal for limiting the output of the electric actuator is output during the output limit control.

  In the work vehicle control method according to this aspect, when the storage amount becomes equal to or less than the first threshold, the output of the engine is reduced and the output of the electric actuator is limited. Therefore, compared with the case where the output of an electric actuator is not restrict | limited, the output of the engine distributed to a hydraulic pump can be ensured largely. Thus, in the hybrid work vehicle, when the amount of reducing agent stored is reduced, the operations of both the hydraulic device and the electric device can be efficiently ensured.

  The work vehicle control method may further include the following steps. In the fourth step, the output of the generator motor necessary for driving the electric actuator is calculated. In the fifth step, the absorption torque of the hydraulic pump is determined based on the reduced engine output and the generator motor output required for driving the electric actuator. In the sixth step, a command signal indicating the determined absorption torque of the hydraulic pump is output.

  In this case, the generator motor output necessary for driving the electric actuator is first calculated, and the absorption torque of the hydraulic pump is determined based on the calculation result, thereby efficiently generating the generator motor necessary for driving the electric actuator. And the absorption torque of the hydraulic pump can be determined. As a result, in the hybrid work vehicle, when the amount of reducing agent stored is reduced, the operations of both the hydraulic device and the electric device can be ensured as efficiently as possible.

  The work vehicle control method may further include the following steps. In the seventh step, a stop command is output to the electric actuator when the storage amount is equal to or smaller than a second threshold value that is smaller than the first threshold value. In the eighth step, after the stop command is output, when the operating speed of the electric actuator decreases to a predetermined speed and the torque command value to the generator motor is 0, the stop signal of the power control device is output.

  In this case, it is possible to avoid stopping the power control device during the operation of the electric actuator. Further, it is possible to avoid stopping the power control device during power generation by the generator motor. Thereby, it is possible to prevent the power control device from being damaged by the power generated by the generator motor after the power control device is stopped.

  According to the present invention, in a hybrid type work vehicle, when the amount of reducing agent stored is reduced, the operation of both the hydraulic equipment and the electric equipment is ensured as efficiently as possible while reducing the output of the engine. can do.

1 is a perspective view of a work vehicle according to an embodiment. It is a schematic diagram which shows the structure of the electric equipment system and hydraulic equipment system of a working vehicle. It is a mimetic diagram showing composition of an exhaust treatment system of a work vehicle. It is a schematic diagram which shows the structure of the control system of a work vehicle. It is a figure which shows an example of an engine torque curve. It is a figure which shows an example of the pump absorption torque line at the time of compound operation. It is a flowchart which shows the process in output restriction control. It is a figure which shows an example of the derate engine torque curve in output restriction control. It is a figure which shows distribution of the engine output torque which concerns on embodiment and a comparative example.

  Hereinafter, a working vehicle according to an embodiment will be described with reference to the drawings. FIG. 1 is a perspective view of a work vehicle 100 according to the embodiment. In the present embodiment, the work vehicle 100 is a hydraulic excavator. The work vehicle 100 includes a vehicle body 1 and a work implement 4.

  The vehicle body 1 includes a traveling body 2 and a turning body 3. The traveling body 2 includes a pair of traveling devices 2a and 2b. Each traveling device 2a, 2b has crawler belts 2d, 2e. Traveling devices 2a and 2b drive work vehicle 100 by driving crawler belts 2d and 2e.

  The swivel body 3 is placed on the traveling body 2. The swivel body 3 is provided so as to be turnable with respect to the traveling body 2. The turning body 3 turns when a turning motor 32 (see FIG. 2) described later is driven. The revolving unit 3 is provided with a cab 5. The swivel body 3 has an engine room 20. The engine compartment 20 is disposed behind the cab 5. The engine chamber 20 houses devices such as an engine 21 and a hydraulic pump 25 described later.

  The work machine 4 is attached to the swing body 3. The work machine 4 includes a boom 7, an arm 8, a work attachment 9, a boom cylinder 10, an arm cylinder 11, and an attachment cylinder 12. A base end portion of the boom 7 is operably connected to the swing body 3. The distal end portion of the boom 7 is operably connected to the proximal end portion of the arm 8. The distal end portion of the arm 8 is operably connected to the work attachment 9.

  The boom cylinder 10, the arm cylinder 11, and the attachment cylinder 12 are hydraulic actuators that are driven by hydraulic oil discharged from a hydraulic pump 25 described later. The boom cylinder 10 operates the boom 7. The arm cylinder 11 operates the arm 8. The attachment cylinder 12 operates the work attachment 9. The work machine 4 is driven by driving these cylinders 10-12. In the present embodiment, the work attachment 9 is a bucket, but may be another attachment such as a crusher or a breaker.

  FIG. 2 is a schematic diagram showing the configuration of the electric equipment system and the hydraulic equipment system of the work vehicle 100. The engine 21 is, for example, a diesel engine. The output horsepower of the engine 21 is controlled by adjusting the amount of fuel injected into the cylinder of the engine 21. This adjustment is performed by the electronic governor 23 attached to the fuel injection pump 22 of the engine 21 being controlled by a command signal from the controller 60. As the governor 23, an all-speed control type governor is generally used, and the engine rotation speed and the fuel injection amount are adjusted according to the load so that the engine rotation speed becomes a target rotation speed described later. That is, the governor 23 increases or decreases the fuel injection amount so that the deviation between the target rotation speed and the actual engine rotation speed is eliminated.

  The actual rotation speed of the engine 21 is detected by the engine rotation speed detection unit 24. The engine speed detected by the engine speed detector 24 is input to the controller 60 as a detection signal. The output of the engine 21 is distributed to the hydraulic equipment system and the electrical equipment system, and drives those equipment. The hydraulic equipment system will be described below.

  The work vehicle 100 has a hydraulic pump 25. The hydraulic pump 25 is connected to the output shaft of the engine 21. The hydraulic pump 25 is driven by the rotation of the output shaft of the engine 21. The hydraulic pump 25 is a variable displacement hydraulic pump. The hydraulic pump 25 has a swash plate 26, and the displacement of the hydraulic pump 25 changes as the tilt angle of the swash plate 26 changes.

  The pump control valve 27 operates in response to a command signal input from the controller 60, and controls the hydraulic pump 25 via a servo piston. The pump control valve 27 has a pump absorption torque corresponding to the command value (command current value) of the command signal input from the controller 60 to the pump control valve 27, as the product of the discharge pressure of the hydraulic pump 25 and the capacity of the hydraulic pump 25. The tilt angle of the swash plate 26 is controlled so as not to exceed.

  The hydraulic oil discharged from the hydraulic pump 25 is supplied to the hydraulic actuator 10-14 via the operation valve 28. Specifically, the hydraulic oil is supplied to the boom cylinder 10, the arm cylinder 11, the attachment cylinder 12, the right traveling motor 13, and the left traveling motor 14. By driving the boom cylinder 10, the arm cylinder 11, and the attachment cylinder 12, the boom 7, the arm 8, and the work attachment 9 are operated. Further, when the right traveling motor 13 and the left traveling motor 14 are driven, the traveling devices 2a and 2b are operated, and the vehicle travels.

  The discharge pressure of the hydraulic pump 25 is detected by the discharge pressure detector 29. The discharge pressure of the hydraulic pump 25 detected by the discharge pressure detection unit 29 is input to the controller 60 as a detection signal.

  The operation valve 28 is a flow direction control valve having a plurality of control valves corresponding to the respective hydraulic actuators 10-14. The operation valve 28 controls the flow rate of the hydraulic oil supplied to each of the hydraulic actuators 10-14.

  Next, the electric equipment system will be described. The work vehicle 100 includes a generator motor 31, a turning motor 32, a power storage device 33, and a power control device 34. The generator motor 31 is connected to the output shaft of the engine 21. The generator motor 31 performs a power generation action and an electric action depending on the situation.

  Electric power is stored in the power storage device 33 by the generator motor 31 generating power. The power storage device 33 is, for example, a capacitor. However, the power storage device 33 is not limited to a capacitor, and may be another type of power storage device. The power storage device 33 supplies power to the turning motor 32. When the generator motor 31 performs an electric action, the power storage device 33 supplies power to the generator motor 31.

  The generator motor 31 performs an electric action when the output of the engine 21 is insufficient. The generator motor 31 is driven by power supplied from the power storage device 33, thereby assisting the engine 21.

  The turning motor 32 is an electric motor that is driven by power supplied from the power storage device 33 or the generator motor 31. The turning motor 32 is driven by electric power from the power storage device 33 or the generator motor 31 to turn the turning body 3 described above. Further, when the swing body 3 is decelerated, the swing motor 32 performs a regenerative operation. That is, the turning motor 32 generates power by regenerating the deceleration energy of the turning body 3 and supplies the generated power to the power storage device 33.

  The turning motor 32 is provided with a motor rotation detector 35 that detects the rotation speed of the turning motor 32. The rotation speed of the turning motor 32 detected by the motor rotation detector 35 is input to the controller 60.

  The power control device 34 is electrically connected to the generator motor 31, the turning motor 32, and the power storage device 33. The power control device 34 controls the power supplied to the generator motor 31, the turning motor 32, and the power storage device 33. The power control device 34 includes a first inverter 36, a second inverter 37, and a booster 38.

  The first inverter 36 is connected to the generator motor 31. A second inverter 37 is connected to the first inverter 36, and a turning motor 32 is connected to the second inverter 37. The booster 38 is connected between the first inverter 36 and the second inverter 37. The booster 38 is connected to the power storage device 33 via the contactor 39.

  The contactor 39 normally energizes the electrical circuit between the power storage device 33 and the booster 38 by closing the electrical circuit. The contactor 39 opens an electric circuit in accordance with a command from the controller 60 in an abnormal state, and puts it into a cut-off state.

  The first inverter 36 converts AC power generated by the generator / motor 31 into DC power when the power generated by the generator / motor 31 is charged in the power storage device 33. The first inverter 36 converts the DC power stored in the power storage device 33 into AC power when power is supplied from the power storage device 33 to the generator motor 31.

  The second inverter 37 converts AC power generated by the swing motor 3229 into DC power when the electric power generated by the swing motor 32 is charged in the power storage device 33. When power is supplied from the power storage device 33 to the turning motor 32, the second inverter 37 converts the DC power stored in the power storage device 33 into AC power.

  The booster 38 is controlled by the controller 60 to control the output power from the booster 38. The booster 38 boosts the voltage of power supplied from the power storage device 33 to the generator motor 31 via the first inverter 36 when the generator motor 31 is electrically operated. When the swing motor 32 is driven, the booster 38 boosts the voltage of the electric power supplied from the power storage device 33 to the swing motor 32 via the second inverter 37. In addition, the booster 38 drops the voltage supplied to the power storage device 33 when charging the power storage device 33 with the power generated by the generator motor 31 or the swing motor 32.

  A voltage detection unit 41 is provided between the booster 38 and the first and second inverters 36 and 37. The voltage detector 41 detects the magnitude of the voltage boosted by the booster 38. The voltage detected by the voltage detector 41 is input to the controller 60.

  The second inverter 37 is provided with a current detection unit 42. The current detection unit 42 detects a current input to the second inverter 37. The current input to the second inverter 37 detected by the current detector 42 is input to the controller 60.

  The power storage device 33 is provided with a storage voltage detection unit 43. The stored voltage detection unit 43 detects the voltage of the power stored in the power storage device 33. The voltage of the power stored in the power storage device 33 detected by the stored voltage detection unit 43 is input to the controller 60. The controller 60 monitors the charge amount of the power storage device 33 from the voltage of the power stored in the power storage device 33.

  As shown in FIG. 2, the work vehicle 100 includes a work machine operation unit 15. The work machine operation unit 15 is operated by an operator to operate the work machine 4. The work machine operation unit 15 includes, for example, an operation lever. The operation amount of the work machine operation unit 15 is input to the controller 60. Specifically, the operation amount of the work implement operation unit 15 for operating the boom 7 (hereinafter referred to as “boom operation amount”) and the operation amount of the work implement operation unit 15 for operating the arm 8 (hereinafter referred to as “boom operation amount”). The operation amount of the work machine operation unit 15 for operating the work attachment 9 (hereinafter referred to as “attachment operation amount”) is input to the controller 60.

  The operation valve 28 described above is controlled in accordance with the operation amount of the work implement operation unit 15. The operation valve 28 changes the opening area of the control valve corresponding to each hydraulic cylinder 10-12 of the work implement 4 according to the operation amount of the work implement operation unit 15. As a result, each hydraulic cylinder 10-12 operates at a speed corresponding to the operation amount of the work implement operation unit 15.

  The work vehicle 100 includes a travel operation unit 16. The travel operation unit 16 is operated by an operator to operate the right travel motor 13 and the left travel motor 14. The traveling operation unit 16 includes, for example, an operation lever or an operation pedal. Either the right traveling motor 13 or the left traveling motor 14 is driven according to the operation direction of the traveling operation unit 16. The operation amount of the travel operation unit 16 is input to the controller 60. Specifically, an operation amount of the travel operation unit 16 for operating the right travel motor 13 (hereinafter referred to as “right travel operation amount”) and an operation amount of the travel operation unit 16 for operating the left travel motor 14. (Hereinafter referred to as “left travel operation amount”) is input to the controller 60.

  The operation valve 28 changes the opening area of the control valve corresponding to the left and right traveling motors 13 and 14 according to the operation amount of the traveling operation unit 16. Accordingly, the left and right traveling motors 13 and 14 are operated at a speed corresponding to the operation amount of the traveling operation unit 16.

  For example, a pilot pressure corresponding to the operation amount of the work implement operation unit 15 and the operation amount of the travel operation unit 16 may be applied to the pilot port of the operation valve 28. Thereby, the opening area of each control valve of the operation valve 28 is changed according to each operation amount. Alternatively, the operation valve 28 may be electrically controlled by the controller 60. In this case, the controller 60 inputs a command signal corresponding to the operation amount of the work implement operation unit 15 and the operation amount of the travel operation unit 16 to the operation valve 28.

  The work vehicle 100 includes a turning operation unit 17. The turning operation unit 17 is operated by an operator to operate the turning motor 32. The turning operation unit 17 includes, for example, an operation lever. The rotation direction of the turning motor 32 is switched according to the operation direction of the turning operation unit 17. The operation amount of the turning operation unit 17 is input to the controller 60. The controller 60 controls the power supplied to the turning motor 32 according to the operation amount of the turning operation unit 17. Thereby, the turning body 3 turns at a speed corresponding to the operation amount of the turning operation unit 17.

  The work vehicle 100 includes a display device 18. The display device 18 displays information on the work vehicle 100 such as the engine rotation speed. The work vehicle 100 has an input device 19. The input device 19 is a device for inputting various settings of the work vehicle 100 such as a work mode setting described later. The display device 18 and the input device 19 may be integrally provided by a touch panel type monitor device.

  Next, the exhaust treatment system of the work vehicle 100 will be described. FIG. 3 is a schematic diagram showing an exhaust treatment system of work vehicle 100. As shown in FIG. 3, the work vehicle 100 includes a first exhaust treatment device 45 and a second exhaust treatment device 46. The first exhaust treatment device 45 is, for example, a diesel particulate filter device. The first exhaust treatment device 45 is connected to the engine 21 and purifies particulate matter (PM) in the exhaust.

  The second exhaust treatment device 46 is connected to the first exhaust treatment device 45 via a mixing pipe 47. The second exhaust treatment device 46 is, for example, a selective catalyst reduction device. The second exhaust treatment device 46 purifies nitrogen oxide (NOx) in the exhaust with a catalyst using a reducing agent such as urea water. The exhaust gas purified by the first exhaust treatment device 45 and the second exhaust treatment device 46 is discharged to the outside of the work vehicle 100 through the exhaust pipe 48 shown in FIG.

  A reducing agent injection device 49 is attached to the mixing pipe 47. The reducing agent injection device 49 injects the reducing agent into the mixing pipe 47. The reducing agent injection device 49 is connected to a reducing agent pump 51 and a reducing agent tank 52 via a reducing agent hose 50. The reducing agent tank 52 stores a reducing agent. The reducing agent pump 51 pumps the reducing agent from the reducing agent tank 52 and sends it to the reducing agent injection device 49.

  The reducing agent tank 52 is provided with a storage amount detection unit 53. The storage amount detection unit 53 detects the storage amount of the reducing agent in the reducing agent tank 52. The storage amount detection unit 53 inputs the detected storage amount of the reducing agent to the controller 60.

  Next, control executed by the controller 60 will be described. FIG. 4 is a schematic diagram showing the configuration of the control system of work vehicle 100. As shown in FIG. 4, the controller 60 is realized by a computer having a storage unit 62 such as a RAM and a ROM, and a calculation unit 61 such as a CPU. The controller 60 is programmed to control the engine 21, the hydraulic equipment system, and the electrical equipment system. The controller 60 may be realized by a plurality of computers. As shown in FIG. 4, the controller 60 includes an engine control unit 63, a pump control unit 64, and an electric actuator control unit 65.

  The engine control unit 63 controls the engine 21 based on the engine torque curves P1 and E1 shown in FIG. Engine torque curves P1 and E1 represent upper limit values of torque that the engine 21 can output according to the rotational speed. That is, the engine torque curves P1 and E1 define the relationship between the engine speed and the upper limit value of the output torque of the engine 21. The engine torque curves P1 and E1 are stored in the storage unit 62.

  The engine control unit 63 determines the target rotational speed of the engine 21 from the operation amount of the work implement operation unit 15, the operation amount of the travel operation unit 16, and the operation amount of the turning operation unit 17. The operation amount of the work implement operation unit 15 is the sum of the above-described boom operation amount, arm operation amount, and attachment operation amount. The operation amount of the travel operation unit 16 is the sum of the left travel operation amount and the right travel operation amount. For example, the engine control unit 63 determines the target rotation speed of the engine 21 according to the sum of the operation amount of the work implement operation unit 15, the operation amount of the travel operation unit 16, and the operation amount of the turning operation unit 17. The governor 23 controls the output of the engine 21 so that the actual rotational speed of the engine 21 becomes the target rotational speed while preventing the output torque of the engine 21 from exceeding the engine torque curve.

  In FIG. 5, P1 represents a first engine torque curve. The first engine torque curve P1 corresponds to the rating of the engine 21 or the maximum power output. The first engine torque curve P1 has a maximum torque point Pt and a rated point Pp. In the first engine torque curve P1, the output torque of the engine 21 becomes maximum at the maximum torque point Pt. Further, in the first engine torque curve P1, the output horsepower of the engine 21 becomes maximum at the rated point Pp.

  In the first engine torque curve P1, when the engine rotation speed is in the range from the low idle rotation speed NLi to the engine rotation speed Nt at the maximum torque point Pt, the output torque of the engine 21 is increased according to the increase in the engine rotation speed. Increase. When the engine rotation speed is in the range from Nt to the engine rotation speed Np at the rated point Pp, the output torque of the engine 21 decreases as the engine rotation speed increases.

  In a region exceeding the rated point Pp in the first engine torque curve P1, a regulation line Rm is defined in which the output torque of the engine 21 rapidly decreases due to an increase in engine speed. The regulation line Rm is a line that connects the rated point Pp and the maximum engine speed NHi in the no-load state.

  The engine control unit 63 selects an engine torque curve according to the set work mode. The work mode is set by the operator operating the input device 19. The work mode includes a P mode and an E mode.

  The P mode is a work mode in which the output torque of the engine 21 is large and the workability is excellent. In the P mode, the first engine torque curve P1 shown in FIG. 5 is selected. The E mode is a work mode in which the output torque of the engine 21 is smaller than that in the P mode and has excellent fuel efficiency. In the E mode, the second engine torque curve E1 shown in FIG. 5 is selected. In the second engine torque curve E1, the output torque of the engine 21 is smaller than that in the first engine torque curve P1. A plurality of E modes in which the output torque of the engine 21 is reduced stepwise may be selectable.

  The pump control unit 64 controls the upper limit of the absorption torque of the hydraulic pump 25 based on the pump absorption torque line as indicated by Lp1 and Le1 in FIG. Lp1 is a pump absorption torque line corresponding to the first engine torque curve P1. Le1 is a pump absorption torque line corresponding to the second engine torque curve E1. The pump absorption torque lines Lp1 and Le1 define the relationship with the upper limit value of the absorption torque of the hydraulic pump 25 corresponding to the engine rotation speed. The pump absorption torque lines Lp1 and Le1 are stored in the storage unit 62.

  In the P mode, the pump control unit 64 controls the capacity of the hydraulic pump 25 so that the upper limit of the engine output torque matches the upper limit of the absorption torque of the hydraulic pump 25 at the matching point Mp1 at the target rotational speed N1 of the engine 21. To do. Similarly, in the E mode, the pump control unit 64 adjusts the hydraulic pump 25 so that the upper limit of the engine output torque matches the upper limit of the absorption torque of the hydraulic pump 25 at the matching point Me1 at the target rotational speed N1 of the engine 21. Control the capacity.

  The pump absorption torque lines Lp1 and Le1 shown in FIG. 5 indicate the pump absorption torque lines when the electric actuators such as the swing motor 32 and the generator motor 31 are not used but only the hydraulic actuator is used. ing.

  The electric actuator control unit 65 controls the turning motor 32 and the generator motor 31 by controlling the power control device 34. The electric actuator controller 65 controls the turning motor 32 based on the operation amount of the turning operation unit 17. The electric actuator control unit 65 controls the generator motor 31 based on the actual engine rotation speed, the target rotation speed, the voltage of the power storage device 33, and the like.

  For example, when it is determined that the output of the engine 21 is insufficient based on the actual engine rotation speed, the target rotation speed, the voltage of the power storage device 33, and the like, the electric actuator control unit 65 causes the generator motor 31 to be electrically operated. Assist the engine 21. When the electric actuator controller 65 determines that the output of the engine 21 is not insufficient based on the actual engine speed, the target speed, the voltage of the power storage device 33, etc., the electric motor control unit 65 By doing so, the power storage device 33 is charged.

  When the generator motor 31 is controlled so as to generate power, the electric actuator controller 65 determines the torque command value of the generator motor 31 based on the voltage of the power storage device 33. The electric actuator controller 65 determines the torque command value of the generator motor 31 so that the voltage of the battery is maintained within a predetermined range. The electric actuator controller 65 controls the generator motor 31 so that the actual torque of the generator motor 31 becomes the torque command value.

  The electric actuator control unit 65 determines the target turning speed from the operation amount of the turning operation unit 17. For example, the electric actuator control unit 65 increases the target turning speed according to an increase in the operation amount of the turning operation unit 17. The electric actuator controller 65 determines a torque command value of the turning motor 32 for reaching the target turning speed from the actual turning speed. The electric actuator controller 65 controls the swing motor 32 so that the torque of the swing motor 32 becomes a torque command value.

  When the generator motor 31 performs a power generation operation, part of the engine output torque is used to drive the generator motor 31. Therefore, at the time of the combined operation in which the hydraulic device system and the electric device system are operated simultaneously, the controller 60 executes energy management that distributes the engine output torque to the hydraulic device system and the electric device system. In the energy management in the normal time when the output restriction control described later is not executed, the upper limit of the absorption torque of the hydraulic pump 25 is determined in consideration of the engine output torque distributed to the drive of the generator motor 31.

  Specifically, as shown in FIG. 4, the controller 60 includes an output calculation unit 66. The output calculation unit 66 calculates the output of the generator motor 31 necessary for driving the turning motor 32. For example, the output calculation unit 66 calculates the power required to drive the swing motor 32 from the output torque of the swing motor 32. The output calculation unit 66 determines the amount of power obtained from the power storage device 33 and the amount of power generated by the generator motor 31 in order to obtain the calculated power. The ratio between the amount of power obtained from the power storage device 33 and the amount of power generated by the power generation action of the generator motor 31 is determined according to the amount of power stored in the power storage device 33. The output calculation unit 66 calculates the required output horsepower of the engine 21 from the amount of electric power generated by the generator motor 31 and distributes the engine output torque Thb (which is distributed to the drive of the generator motor 31 from the required output horsepower of the engine 21. Hereinafter, “generator torque Thb”) is determined.

  As shown in FIG. 4, the controller 60 has an absorption torque determination unit 67. The absorption torque determination unit 67 determines the absorption torque of the hydraulic pump 25 based on the generator torque Thb. Specifically, as shown in FIG. 6, a value Tp2 obtained by subtracting the generator torque Thb from the upper limit Tp1 of the pump absorption torque determined based on the pump absorption torque line Lp1 described above is used for the hydraulic pump 25 in the combined operation. Determined as the upper limit of absorption torque.

  In FIG. 6, Lp2 is a pump absorption torque line at the time of combined operation, and defines an upper limit of the absorption torque that is lower than the above-described pump absorption torque line Lp1 by the generator torque Thb. The pump absorption torque line Lp2 at the time of the combined operation is changed according to the increase / decrease in the generator torque Thb.

  The energy management as described above is executed at the time of composite operation in which the electric device system and the hydraulic device system are operated simultaneously. Thus, the sum of the absorption torque of the hydraulic pump 25 and the generator torque is controlled so as not to exceed the engine output torque.

  In the work vehicle 100 according to the present embodiment, the controller 60 executes output restriction control that restricts the output of the engine 21 in accordance with the amount of reducing agent stored in the reducing agent tank 52. Hereinafter, the output restriction control will be described in detail.

  FIG. 7 is a flowchart showing processing in output restriction control. As shown in FIG. 7, in step S1, a reducing agent storage amount A in the reducing agent tank 52 is detected. In step S2, it is determined whether the storage amount A is equal to or less than the threshold value a1. The storage amount A and the threshold value a1 are, for example, the ratio of the remaining amount of reducing agent with the maximum storage amount of the reducing agent tank 52 being 100%. However, the storage amount A and the threshold value a1 are not limited to the ratio of the residual amount, but may be the volume of the reducing agent remaining. The same applies to threshold values a2-a4 described later.

  When the storage amount A is less than or equal to the threshold value a1, a first warning is issued in step S3. The controller 60 causes the display device 18 to display the first warning. The first warning is, for example, a display of a message or the like notifying the operator of a decrease in the storage amount.

  Next, in step S4, it is determined whether or not the storage amount A is equal to or less than the threshold value a2. The threshold value a2 is smaller than the threshold value a1. When the storage amount A is equal to or less than the threshold value a2, a second warning is issued in step S5. The controller 60 causes the display device 18 to display the second warning. The second warning is a display of a message or the like for notifying that the output restriction is executed when the storage amount further decreases.

  Next, in step S6, it is determined whether or not the storage amount A is equal to or less than the threshold value a3. The threshold value a3 is smaller than the threshold value a2. When the storage amount A is equal to or less than the threshold value a3, the first level output restriction is executed in step S7.

  In the first level output restriction, the engine control unit 63 reduces the engine output torque. Specifically, as shown in FIG. 8, the engine control unit 63 outputs a command signal to the governor 23 so as to control the output of the engine 21 with a derate engine torque curve D1. The derated engine torque curve D1 defines an upper limit of output torque lower than the normal engine torque curves P1 and E1 where the storage amount A is larger than the threshold value a3. In other words, the derated engine torque curve D1 defines an upper limit of output torque lower than the engine torque curves P1 and E1 that can be selected by the operator. The derated engine torque curve D1 defines an upper limit of the output torque that is lower than the engine torque curves P1 and E1 at the normal time at least in an engine rotation speed range equal to or greater than the maximum torque point Pt.

  Further, in the first level output restriction, the electric actuator control unit 65 outputs a command signal to the second inverter 37 so as to restrict the output of the turning motor 32. Specifically, the electric actuator control unit 65 reduces the upper limit of the torque of the turning motor 32. For example, the electric actuator control unit 65 reduces the upper limit of the torque command value of the turning motor 32. Accordingly, the turning speed is lower than the target turning speed corresponding to the operation amount of the turning operation unit 17.

  In the first level output limitation, the absorption torque determination unit 67 determines the absorption torque of the hydraulic pump 25 based on the output of the engine 21 reduced by the first level output limitation and the generator torque Thb. . Specifically, as shown in FIG. 9, with the first level output restriction, the engine output torque is reduced from the normal upper limit value Te to Te ′. The absorption torque determination unit 67 determines the absorption torque Tp ′ of the hydraulic pump 25 at the first level output restriction by subtracting the generator torque Thb ′ from the reduced engine output torque Te ′. The pump control unit 64 outputs a command signal indicating the determined absorption torque Tp ′ of the hydraulic pump 25 to the pump control valve 27. Thereby, the hydraulic pump 25 is controlled by the determined absorption torque Tp ′.

  The generator torque Thb 'at the first level output restriction is calculated by the output calculation unit 66 in the same manner as the normal generator torque Thb described above. As described above, since the torque command value of the swing motor 32 is reduced when the output of the first level is limited, the generator torque Thb ′ at the output limit of the first level is the normal generator torque. It becomes smaller than Thb.

  Next, in step S8, it is determined whether or not the storage amount A is equal to or less than the threshold value a4. The threshold value a4 is smaller than the threshold value a3. When the storage amount A is equal to or less than the threshold value a4, the output restriction of the second level is executed in step S9.

  In the second level output restriction, the engine control unit 63 further reduces the engine output torque as compared with the first level output restriction. Specifically, as shown in FIG. 8, the engine control unit 63 controls the output of the engine 21 with a derated engine torque curve D2. The derated engine torque curve D2 defines an upper limit of output torque lower than the derated engine torque curve D1. Further, the derated engine torque curve D2 limits the upper limit of the engine rotation speed to Nd.

  In the second level output restriction, the electric actuator controller 65 stops the turning motor 32. Specifically, the electric actuator control unit 65 sets the torque command value of the turning motor 32 to zero.

  Next, in step S10, the electric actuator control unit 65 determines whether or not a predetermined system stop condition is satisfied. When the predetermined system stop condition is satisfied, the electric actuator control unit 65 outputs a stop command to the power control device 34 in step S11. As a result, the entire electrical equipment system is stopped.

Specifically, the system stop condition is that both of the following two conditions are satisfied.
(Condition 1) The operation speed of the turning motor 32 is reduced to a predetermined speed or less.
(Condition 2) The torque command value to the generator motor 31 is zero.

  Therefore, after the output torque of the engine is reduced by the second level output restriction and the stop of the turning motor 32 is instructed, the operating speed of the turning motor 32 is reduced to a predetermined speed or less, and the generator motor 31 When power generation is stopped, the entire electrical equipment system is stopped.

  Next, in step S12, it is determined whether or not the duration T in which the storage amount A is equal to or less than the threshold a4 is equal to or greater than a predetermined time threshold t1. When the duration T is equal to or greater than the time threshold t1, the third level output restriction is executed in step S13.

  In the third level output restriction, the engine control unit 63 controls the output of the engine 21 with a derated engine torque curve D3 as shown in FIG. In the derated engine torque curve D3, the engine rotation speed is limited to the low idle rotation speed NLi.

  In the work vehicle 100 according to the present embodiment described above, the first-level output restriction is performed when the reducing agent storage amount A is equal to or less than the threshold value a3. In the first level output restriction, as shown in FIG. 9, the absorption torque Tp 'of the hydraulic pump 25 is determined based on the reduced engine output torque Te' and the generator torque Thb '. Here, the output torque of the hydraulic pump 25 required for driving the hydraulic actuator 10-14 varies greatly according to the load applied to the work machine 4. Therefore, it is not easy to accurately estimate the torque to be distributed to the hydraulic pump 25 in the output restriction control.

  For example, in the comparative example shown in FIG. 9, the output torque Thb ″ of the generator motor 31 is determined by subtracting the absorption torque Tp ″ of the hydraulic pump 25 from the reduced engine output torque Te ′. In this case, when the absorption torque of the hydraulic pump 25 is actually Tp ′ ″ smaller than the estimated value Tp ″, it corresponds to the hatched portion (Tp ″ −Tp ′ ″) in FIG. The engine output torque is wasted because it is not absorbed by the hydraulic pump 25 and is not used for driving the generator motor 31.

  On the other hand, in the work vehicle 100 according to the present embodiment, the generator torque Thb ′ is first calculated, and the absorption torque Tp ′ of the hydraulic pump 25 is calculated based on the calculation result. The generator torque Thb 'can be accurately calculated from the current value of the swing motor 32 or the like. Therefore, the generator torque Thb 'and the absorption torque Tp' of the hydraulic pump 25 can be determined efficiently. Thus, in the hybrid work vehicle 100, when the amount of reducing agent stored is reduced, the operations of both the hydraulic device and the electric device can be ensured as efficiently as possible.

  When the reducing agent storage amount A becomes equal to or less than the threshold value a4, the second level output restriction is performed. With the output restriction at the second level, the engine output torque is further reduced and the turning motor 32 is stopped. This can further prompt the operator to replenish the reducing agent.

  In addition, when the reducing agent storage amount A is equal to or less than the threshold value a4 and the system stop condition is satisfied, the electric actuator control unit 65 stops the power control device 34. As a result, the entire electrical equipment system is stopped, so that the operator can be further urged to replenish the reducing agent.

  The system stop condition includes that the operating speed of the turning motor 32 has decreased to a predetermined speed. Therefore, the power control device 34 can be stopped while the turning motor 32 is stopped or almost stopped. Thereby, it is possible to avoid stopping the power control device 34 during the operation of the turning motor 32.

  The system stop condition includes that the torque command value to the generator motor 31 is zero. Therefore, it is possible to avoid stopping the power control device 34 during power generation by the generator motor 31. Thereby, it is possible to prevent the power control device 34 from being damaged by the power generated by the generator motor 31 after the power control device 34 is stopped.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

  In the above embodiment, a hydraulic excavator is exemplified as the work vehicle 100, but the present invention may be applied to other types of work vehicles such as a wheel loader. The electric actuator is not limited to the turning motor, and may be a traveling motor, a steering motor, or an electric actuator other than the motor.

  The system stop condition is not limited to the two conditions described above, but may be other conditions. Alternatively, other conditions may be added to the two conditions described above. Alternatively, one of the two conditions described above may be omitted.

  A part of the processing in the output restriction control may be omitted or changed. For example, the third level output restriction may be omitted.

  The limitation on the output of the turning motor 32 may be executed on condition that the engine control unit 63 has executed a process of reducing the engine output torque. The limitation on the output of the turning motor 32 may be executed on the condition that the storage amount is equal to or less than a threshold value.

  According to the present invention, in a hybrid type work vehicle, when the amount of reducing agent stored is reduced, the operation of both the hydraulic equipment and the electric equipment is ensured as efficiently as possible while reducing the output of the engine. can do.

Claims (13)

Engine,
A hydraulic pump driven by the engine;
A hydraulic actuator driven by hydraulic oil discharged from the hydraulic pump;
A generator driven by the engine;
An electric actuator driven by electric power generated by the generator;
An exhaust treatment device for purifying the exhaust of the engine;
A reducing agent tank for storing a reducing agent supplied to the exhaust treatment device;
A storage amount detection unit for detecting a storage amount of the reducing agent in the reducing agent tank;
An engine control unit that performs output restriction control to reduce the output of the engine when the storage amount is equal to or less than a first threshold;
An electric actuator controller that restricts the output of the electric actuator during the execution of the output restriction control;
Work vehicle equipped with. An output calculation unit for calculating an output of the generator necessary for driving the electric actuator when the storage amount is equal to or less than a first threshold;
An absorption torque determining unit that determines an absorption torque of the hydraulic pump based on the reduced output of the engine and the output of the generator necessary for driving the electric actuator;
A pump controller that controls the hydraulic pump with the determined absorption torque;
The work vehicle according to claim 1, further comprising: When the storage amount is equal to or less than a second threshold value less than the first threshold value, the electric actuator control unit stops the electric actuator;
The work vehicle according to claim 1 or 2. A power control device electrically connected to the generator and the electric actuator;
When the storage amount is equal to or less than the second threshold and a predetermined system stop condition is satisfied, the electric actuator control unit stops the power control device;
The work vehicle according to claim 3. The system stop condition includes that the operating speed of the electric actuator has decreased to a predetermined speed.
The work vehicle according to claim 4. The system stop condition further includes a torque command value to the generator being 0,
The work vehicle according to claim 5. When the storage amount is less than or equal to the second threshold, the electric actuator control unit sets a torque command value to the electric actuator to 0,
The work vehicle according to any one of claims 3 to 6. The engine control unit controls the output of the engine with a first engine torque curve at a normal time when the storage amount is larger than the first threshold,
The engine control unit controls the output of the engine with a second engine torque curve that defines an output of the engine lower than the first engine torque curve in the output restriction control.
The work vehicle according to any one of claims 1 to 7. The electric actuator controller reduces the upper limit of the output torque of the electric actuator in the output restriction control;
The work vehicle according to any one of claims 1 to 8. A traveling body,
A swivel body supported so as to be turnable with respect to the traveling body;
Further comprising
The electric actuator is an electric motor that rotates the revolving structure.
The work vehicle according to any one of claims 1 to 9. Detecting the amount of reducing agent stored in the reducing agent tank;
Performing output restriction control for outputting a signal for reducing the output of the engine when the storage amount is equal to or less than a first threshold;
Outputting a signal for limiting the output of the electric actuator during the execution of the output restriction control;
A method for controlling a work vehicle. Calculating an output of a generator necessary for driving the electric actuator;
Determining the absorption torque of the hydraulic pump based on the reduced output of the engine and the output of the generator required to drive the electric actuator;
Outputting a command signal indicating the determined absorption torque of the hydraulic pump;
The work vehicle control method according to claim 11, further comprising: Outputting a stop command to the electric actuator when the storage amount is equal to or smaller than a second threshold value that is smaller than the first threshold value;
After the output of the stop command, when the operating speed of the electric actuator decreases to a predetermined speed and the torque command value to the generator is 0, the power control device of the generator and the electric actuator Outputting a stop signal;
The work vehicle control method according to claim 12, further comprising:

Images