WO2014087978A1

WO2014087978A1 - Work machine

Info

Publication number: WO2014087978A1
Application number: PCT/JP2013/082401
Authority: WO
Inventors: 星野　雅俊; 園田　光夫; 坂本　博史; 新士石原
Original assignee: 日立建機株式会社
Priority date: 2012-12-03
Filing date: 2013-12-02
Publication date: 2014-06-12
Also published as: JPWO2014087978A1; JP6126625B2

Abstract

A work machine is provided with an inverter (9A) for controlling an assist torque amount (Tm) to an engine from a motor generator (2) on the basis of the size of a deviation (e) of the actual speed of the engine (1) from a target speed, and a pump control device (45) for controlling an absorption torque limit amount (Tp1) of a variable-displacement hydraulic pump (3) on the basis of the size of the deviation (e). The ratio of the size of the assist torque amount (Tm) and the size of the absorption torque limit amount (Tp1) is such that the size of the absorption torque limit amount (Tp1) is set to be greater when a deviation (e) occurs due to a stall in the engine, and the size of the assist torque amount (Tm) is set to be greater when a deviation (e) occurs due to engine acceleration.

Description

Work machine

The present invention relates to a working machine provided with a hydraulic pump, an engine for driving the hydraulic pump, and a motor for assisting the engine.

In working machines including construction machines and industrial machines, a hydraulic pump for supplying pressure oil to a hydraulic actuator, an engine for driving the hydraulic pump, and an electric motor (or motor generator for assisting the engine There is a hybrid type provided with.

By the way, in a conventional hydraulic shovel that does not have an electric motor for engine assist, when the load of the variable displacement hydraulic pump rises, the load on the hydraulic pump may be reduced to suppress an increase in the load on the engine. However, when the capacity of the hydraulic pump is reduced as described above, the flow rate of the hydraulic oil supplied to the hydraulic actuator (for example, a boom cylinder or the like) is reduced, which may lower the operability of the boom or the like.

In this regard, Japanese Patent Application Laid-Open No. 2009-174447 discloses that, in the hybrid work machine (hydraulic shovel) as described above, when it is predicted that the variable displacement hydraulic pump is overloaded, the motor is driven by the electric motor. It is disclosed to aim at suppression of operativity fall, without changing the capacity of the hydraulic pump concerned by assisting.

2009-174447 gazette

However, in the technique of the above-mentioned document, when the pump load is predicted to be overloaded, the engine assist is performed by the electric motor. Therefore, depending on the status of the working machine, the engine assist may lower operability and power consumption May be promoted.

In the technique of the above document, when it is predicted that the pump load is overloaded, engine assist by the motor is immediately started. Therefore, for example, when the engine rotational speed is set to be lower than the rated rotational speed (for example, when using automatic idling control that automatically reduces the engine rotational speed from the viewpoint of fuel efficiency improvement and quietness securing) When the load is predicted to be overloaded and engine assist is started, the motor assist alone can not support the load, and it is necessary to limit the absorption torque of the hydraulic pump, which may eventually reduce operability. .

Further, even if the load of the hydraulic pump can be coped with by the assist of the electric motor, energy is increased by the amount necessary for the assist by the electric motor compared to when the engine is operated at the rated without the need of assist Consumption tends to increase. For this reason, in the case where a battery (power storage device) is provided as a power source to the electric motor that can generate electric power, the necessity of driving the electric motor as an electric generator as an engine increases and the fuel consumption may increase. On the other hand, when power generation is impossible and charging is not performed during work, the time during which the motor can assist the engine decreases. As described above, even if the assist torque is generated by the motor while maintaining the capacity of the hydraulic pump as in the technique of the above-mentioned document, there may be a case where operability decreases or fuel efficiency decreases (power consumption increases). is there.

An object of the present invention is to provide a working machine capable of suppressing the decrease in operability and the increase in power consumption as much as possible depending on the situation.

The present invention achieves the above object by providing an engine, a motor generator that transmits torque between the engine, and a variable displacement hydraulic pump driven by at least one of the engine and the motor generator. And controlling an amount of assist torque to the engine by the motor generator based on a hydraulic actuator driven by pressure oil discharged from the hydraulic pump, and a target rotation speed and an actual rotation speed of the engine. A motor control unit, and a pump control unit for controlling an absorption torque limit amount of the hydraulic pump based on values of a target rotation speed and an actual rotation speed of the engine, the target rotation speed and the actual rotation speed of the engine When it is determined based on the value that the engine lags down, the absorption torque limit amount is set larger than the assist torque amount, and When it is determined that the acceleration of the engine based on the target rotational speed and the value of the actual rotational speed of the engine shall be the absorption torque restriction rate than the larger is the assist torque amount.

According to the present invention, it is possible to quickly reach the target rotational speed without losing operability when the engine accelerates, and to quickly return to the target rotational speed while suppressing excessive power consumption when the engine lag is down.

BRIEF DESCRIPTION OF THE DRAWINGS The external view of the hybrid type hydraulic shovel concerning embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram of the actuator drive control system in the hybrid type hydraulic shovel concerning embodiment of this invention. The control characteristic view of the pump absorption torque by the regulator which concerns on embodiment of this invention. The figure which showed a part of schematic structure of the control apparatus 8 which concerns on embodiment of this invention. The figure which showed a part of schematic structure of the control apparatus 8 which concerns on embodiment of this invention. FIG. 7 is a view schematically showing the magnitude relationship between the magnitude of the assist torque amount Tm and the magnitude of the absorption torque limit amount Tp1 in the present embodiment.

Hereinafter, embodiments of the present invention will be described using the drawings.
FIG. 1 is an external view of a hybrid hydraulic shovel according to an embodiment of the present invention. The hydraulic shovel shown in this figure includes an articulated work apparatus 100A having a boom 100a, an arm 100b and a bucket 100c, and a vehicle body 100B having an upper swing body 100d and a lower traveling body 100e.

The boom 100 a is rotatably supported by the upper swing body 100 d and driven by a hydraulic cylinder (boom cylinder) 91. The arm 100 b is rotatably supported by the boom 100 a and driven by a hydraulic cylinder (arm cylinder) 92. The bucket 100 c is rotatably supported by the arm 100 b and driven by a hydraulic cylinder (bucket cylinder) 93. The upper swing structure 100d is driven to rotate by a motor (swing motor) 19 (see FIG. 2), and the lower traveling vehicle 100e is driven by left and right traveling motors (hydraulic motors) 95 and 96. The hydraulic cylinder 91, the hydraulic cylinder 92, the hydraulic cylinder 93, and the traveling motors 95, 96 are driven by pressure oil pumped up from a tank (not shown) by the hydraulic pump 3 (see FIG. 2).

FIG. 2 is a schematic configuration diagram of an actuator drive control system in the hybrid hydraulic shovel shown in FIG. The same reference numerals are given to the same parts as the parts shown in the previous figures, and the description may be omitted as appropriate (the same applies to the latter figures).

The actuator drive control system shown in this figure is a variable displacement hydraulic pump driven by at least one of an engine 1 and a motor generator 2 that transmits torque between the engine 1 and the engine 1. 3 (hereinafter sometimes referred to simply as “hydraulic pump 3”) and a hydraulic actuator 5 driven by pressure oil discharged from the hydraulic pump 3 (eg,

hydraulic cylinders

91, 92, 93 shown in FIG. 1) Electric power supplied to the hydraulic motor 95, 96), the pump control device (pump control unit) 45 for controlling the absorption torque by adjusting the capacity of the hydraulic pump 3, the motor generator 2, the swing motor 19 and the like An inverter for controlling transfer of electric power between the motor generator 2 and the storage device 10 as well as controlling the storage device (storage means) 10 to be stored and the motor generator 2 (Power conversion device) 9A and inverter (power conversion device) 9B for controlling transfer of power between the swing motor 19 and the storage device 10 together with control of the swing motor 19, hydraulic actuator 5 and swing motor 19 Operation lever (operation device) 16 that outputs an operation signal for driving the motor based on the operation amount, a governor 7 that adjusts the fuel injection amount of the engine 1, and a rotation number sensor that detects the actual rotation number of the engine Control device 8 that performs actual rotation number detection means 6, rotation control of engine 1, torque control of motor generator 2 and swing motor 19, displacement control of hydraulic pump 3, charge / discharge control of power storage device 10 by output And have.

The control lever 16 reduces the pressure oil discharged from the pilot pump 32 according to the amount of operation, and generates operation signals of the hydraulic actuator 5 and the electric actuator (swing motor 19). As the operation signal of the hydraulic actuator 5, the pressure oil depressurized by the operation lever 16 according to the operation amount is used as it is, and the pressure oil is used in any of a plurality of control valves (not shown) in the valve device 4. It is output and drives the control valve. In the present embodiment, the pressure oil discharged from the hydraulic pump 3 is supplied to the valve device 4, and the flow rate, direction, and pressure of the pressure oil are appropriately changed by the control valve in the valve device 4. Supplied to Thus, the driving of each hydraulic actuator 5 is controlled. On the other hand, as the operation signal of the swing motor 19 (electric actuator) of the present embodiment, the pressure of the pressure oil reduced by the control lever 16 is used. The pressure of the pressure oil is detected by pressure sensors (pressure detectors) 18a and 18b, and the swing motor 19 is controlled by the control device 8 based on the outputs of the

pressure sensors

18a and 18b.

Although only one set of

pressure sensors

18a and 18b is simply shown in FIG. 2, in the present embodiment, the same number of oil passages as the number of directions in which the operation lever 16 can be operated exists. The operation amount of the operation lever 16 is detected based on the detection value of the pressure sensor installed in the oil passage. In addition, the operation amount of the operation lever 16 may be detected, and the hydraulic actuator 5 or the swing motor 19 may be appropriately controlled based on the operation amount. Further, by using a position sensor (for example, a rotary encoder) for detecting the rotational displacement of the operating lever 16 instead of the

pressure sensors

18a and 18b, an electric operation signal corresponding to the operating direction and the operating amount of the operating lever 16 is obtained. A configuration for direct output to the control device 8 may be employed.

The engine 1 is controlled by controlling the fuel injection amount by the governor 7. A pressure sensor 22 (a pressure sensor for measuring the pressure of the pressure oil discharged from the hydraulic pump 3 as a means (pump information detection means) for detecting information necessary for calculating the load of the hydraulic pump 3 to the hydraulic pump 3 A detection means), a flow rate sensor (flow rate detection means) for measuring the flow rate of the pressure oil, and an angle sensor (angle detection means) for measuring the tilt angle of the hydraulic pump 3 are provided. The flow rate sensor and the angle sensor output the detected sensor values to the control device 8.

In the present embodiment, the inverter (motor control unit) 9A controls the amount of assist torque applied to the engine 1 by the motor generator 2 mainly based on the magnitude of the deviation between the target speed of the engine 1 and the actual speed. ing.

The pump control unit (pump control unit) 45 includes the regulator 14 and the solenoid proportional valve 15. In the present embodiment, the hydraulic pressure is mainly based on the difference between the target rotation speed of the engine 1 and the actual rotation speed. The absorption torque limit amount of the pump 3 is controlled. The regulator 14 is provided to the hydraulic pump 3, and when the tilt angle of the swash plate or the oblique shaft of the hydraulic pump 3 is operated by the regulator 14, the displacement (displacement volume) of the hydraulic pump 3 is changed to absorb the hydraulic pump 3. Torque (input torque) can be controlled (pump absorption torque control). The regulator 14 in the present embodiment is controlled by the control pressure generated by the solenoid proportional valve 15. The solenoid proportional valve 15 operates based on a signal (volume command) output from the controller 8.

The regulator 14 according to the present embodiment controls, for example, the displacement of the hydraulic pump 3 in accordance with the control characteristic diagram shown in FIG. FIG. 3 is a control characteristic diagram of pump absorption torque by the regulator 14 according to the embodiment of the present invention. The broken line 31A shown in this figure shows the characteristic of the capacity of the hydraulic pump 3 set with respect to the discharge pressure of the hydraulic pump 3, and the maximum value of the total output of the engine 1 and the motor generator 2 (FIG. The torque (the product of the pump displacement and the pump discharge pressure) of the hydraulic pump 3 is set to be substantially constant within a range not exceeding the hyperbola (constant torque diagram) indicated by the broken line. That is, if the capacity of hydraulic pump 3 is set using polygonal line 31A according to the pump discharge pressure at that time, the torque of hydraulic pump 3 can be controlled so as not to exceed the maximum output by engine 1 and motor generator 2 . When the pump discharge pressure is P1 or less, the pump absorption torque control is not performed, and the pump displacement is determined by the operation amount of the operation lever for operating each control valve of the valve device 4 (for example, any operation lever Becomes q1 when the operation amount of is the maximum). On the other hand, when the pump discharge pressure becomes P1 to P2, the pump absorption torque control by the regulator 14 is executed, and the pump displacement angle by the regulator 14 decreases the pump displacement along the broken line 31A with the increase of the pump discharge pressure. Is operated. Thus, the pump absorption torque is controlled to be equal to or less than the torque specified by the broken line 31A. P2 is the maximum value of the pump discharge pressure, which is equal to the set pressure of the relief valve connected to the circuit on the hydraulic pump 3 side in the valve device 4, and the pump discharge pressure does not rise above this value. Here, a broken line 31A in which two straight lines are combined is used as a control characteristic diagram of absorption torque of the hydraulic pump, but if it is set in a range not exceeding the constant torque diagram (hyperbola) in FIG. A control characteristic chart may be used.

The control device 8 (capacity calculation unit 53 (FIG. 5)) outputs a control signal (electric signal) to the solenoid proportional valve 15, and the solenoid proportional valve 15 generates the control pressure according to the operation signal, thereby regulating the regulator 14. Drive. As a result, the displacement of the hydraulic pump 3 is changed by the regulator 14, and the absorption torque of the hydraulic pump 3 is appropriately adjusted in a range where engine stall does not occur.

In the power storage device 10 configured of a secondary battery (battery) or a capacitor, the current sensor 11, a voltage as a means (power storage information detection means) for detecting information necessary to calculate the storage amount of the power storage device 10. A sensor 12 and a temperature sensor 13 are attached. Control device 8 calculates the state of charge (SOC) of power storage device 10 in charge remaining amount calculation unit 54 (described later) based on information such as current, voltage and temperature detected by these

sensors

11, 12 and 13. The storage amount of the storage device 10 is managed.

The control device 8 has a hardware configuration, an arithmetic processing unit (for example, a CPU) as an arithmetic unit for executing various programs, and a storage device (for example, a storage unit for storing various data including the program). , Semiconductor memory such as ROM, RAM and flash memory, magnetic storage device such as hard disk drive), input / output operation processing to perform input / output control such as data and instruction to the operation processing device and the storage device etc The device is provided (none shown). FIGS. 4 and 5 are diagrams showing a part of the schematic configuration of the control device 8 according to the embodiment of the present invention, and even if the above hardware configuration is adopted for each part shown in FIGS. The above hardware configuration may be adopted as a combination of a plurality of parts.

First, as a circuit mainly for controlling the engine 1, the control device 8 is, as shown in FIG. 4, a pump required power calculation unit 41, an adder 42, a target rotation speed calculation unit 43, and an engine control unit (ECU) 44 is provided.

The pump required power calculation unit 41 executes a process of estimating the required power of the hydraulic pump 3 based on the product of the discharge pressure of the hydraulic pump 3 and the flow rate. In the present embodiment, the discharge pressure of the hydraulic pump 3 is determined using the detection value of the pressure sensor 22, and the lever operation amount of the control lever 16 is determined from the detection values of the

pressure sensors

18a and 18b. The flow rate of the hydraulic pump 3 is estimated from the amount.

The adder 42 adds the pump request power input from the pump request power calculation unit 41 and the power generation request power requested by the motor generator 2 and executes the processing to output to the target rotation speed calculation unit 43. is there. The power generation requirement motive power is motive power to be borne by the engine 1 and is set so that the amount of power generation increases according to the decrease in the remaining amount of charge when the amount of remaining charge (amount of charge) of the storage device 10 is small. It is done. The sum of the pump required power and the power generation required power is the power required for the engine 1 (required engine power). Note that the power generation request power may be calculated based on the remaining power amount of the power storage device 10 calculated by the remaining power amount calculation unit 54 in the maximum motor power calculation unit 55 in FIG. 5 described later.

The target rotation speed calculation unit 43 is a part that executes a process of calculating a target rotation speed of the engine 1 based on the required engine power input from the adder 42. By the way, from the viewpoint of fuel consumption, it is desirable that the engine 1 be operated at a rotation speed as small as possible, which is capable of driving the pump 3 and generating electric power. On the other hand, if the engine rotational speed is changed following a small variation in pump power, the engine rotational speed may become unstable in actual operation and operability may deteriorate. Therefore, in the present embodiment, the target rotational speed is set to discretely increase stepwise as the required engine power increases. That is, the target rotational speed is set to be constant for the required engine power in a predetermined range, and the target rotational speed is repeatedly increased by one step when the required engine power increases beyond the range. It is set. Further, since the heights of the respective steps are set to be equal, the increase amount (e1) of the target rotational speed corresponding to the height is set to be constant. Furthermore, in order to prevent hunting when switching the target rotational speed, a hysteresis is provided in the map of the target rotational speed. That is, the value of the required engine power at which the target rotational speed changes is different when the required engine power is increased and decreased.

The target rotation speed output from the target rotation speed calculation unit 43 is output to the engine control unit (ECU) 44. The engine control unit 44 controls the engine 1 so that the actual rotation speed approaches the target rotation speed by appropriately controlling the fuel injection amount with the governor 7. As an example of rotation speed control of the engine 1 by the engine control unit 44, feedback control based on the actual rotation speed input from the rotation speed sensor 6 and the value of the target rotation speed input from the target rotation speed calculation unit 43 is there.

Further, as a circuit for controlling the hydraulic pump 3 and the motor generator 2, as shown in FIG. 5, the control device 8 includes a subtractor (rotational speed deviation calculator) 51, an assist torque calculation unit 70, and storage of electricity. A remaining amount calculation unit 54, a maximum motor power calculation unit 55, a divider (torque calculator) 56, a minimum value selector 57, a first limit torque calculation unit 60, and a second limit torque calculation unit 80; An adder 52 and a capacity calculation unit 53 are provided.

The target rotational speed output from the target rotational speed calculation unit 43 and the actual rotational speed output from the rotational speed sensor 6 are input to the subtractor 51, and the actual rotational speed is subtracted from the target rotational speed By doing this, the rotational speed deviation e is calculated. Deviation e occurs (1) when the target rotational speed increases with respect to the actual rotational speed, and (2) when the actual rotational speed decreases with respect to the target rotational speed. When the target rotational speed is determined by the target rotational speed calculation unit 43 as shown in FIG. 4, for example, when the pump required power increases, the deviation e occurs due to the increase of the target rotational speed with respect to the actual rotational speed. (Case (1) above). Then, after the target rotational speed reaches the maximum value and the deviation e is eliminated, if the pump request power further increases, the actual rotational speed decreases with respect to the target rotational speed and the deviation e occurs again ( Case (2) above). Since the engine 1 generates torque so as to eliminate both deviations e, if the pump required power is smaller than the maximum torque of the engine 1, the deviation e becomes smaller gradually.

Here, a state in which the target rotation speed increases with respect to the actual rotation speed and the generated deviation e is eliminated is referred to as “acceleration”, and when the target rotation speed is the maximum value, the target rotation is increased by the engine load. A state where the actual rotation speed decreases with respect to the number and the generated deviation e increases is referred to as “lag down (engine lag down)”. Then, in the present embodiment, the simplification is further advanced, and it is determined that "acceleration" is performed when the magnitude of the deviation e is equal to or larger than the set value N1, and when the magnitude of the deviation e is smaller than the set value N1. Shall be judged as "lag down". The determination result affects the magnitude relationship (ratio) between the magnitude of the absorption torque limit amount Tp1 calculated by the limit torque calculation unit 60 described later and the magnitude of the assist torque amount Tm calculated by the assist torque calculation unit 70. give. In this embodiment, as shown in FIG. 4, the target rotational speed is increased stepwise in proportion to the increase of the required engine power. If the height is set large, “acceleration” and “lag down” can be determined by setting the deviation corresponding to the height of the step as the set value N1. Therefore, in the following, using the rotational speed deviation e1 (see FIG. 4) corresponding to one step of the stairs of the target rotational speed calculation unit 43 of FIG. 4 as the setting value N1 (ie, “N1 = e1”) The explanation is based on

Of course, it is also possible to improve the determination accuracy of acceleration and lag-down by determining not only the deviation e but also the target rotation speed itself. In addition, even when the target rotation speed is not set stepwise as in FIG. 1 but continuously set, it is possible to determine “acceleration” and “lag down” based on the change in the target rotation speed and the deviation e.

The assist torque calculation unit 70 is a part that executes a process of calculating an assist torque amount Tm to the engine 1 by the motor generator 2 based on the rotational speed deviation e output from the subtractor 51. The first limit torque calculation unit 60 is a part that executes a process of calculating the absorption torque limit amount Tp1 of the hydraulic pump 3 based on the rotational speed deviation e output from the subtractor 51. The ratio of the magnitude of the assist torque amount Tm to the magnitude of the absorption torque limit amount Tp1 is set larger in the magnitude of the absorption torque limit amount Tp1 when it is determined that the deviation e is generated due to the lag-down. When it is determined that the deviation e has occurred, the magnitude of the assist torque amount Tm is set larger. Next, in order to realize the said function, the structure which the control apparatus 8 which concerns on this Embodiment comprised was demonstrated.

In order to realize the above function, the assist torque calculation unit 70 calculates the assist torque Tm based on the deviation e, and the assist torque Tm output from the PI control unit 71 is used as the motor generator 2 appropriately. And a correction unit 78 that corrects from the viewpoint of proper control. The PI control unit 71 includes a proportional gain (Kp) calculation unit 72, an integral gain (Ki) calculation unit 73, a multiplier 74, a multiplier 75, an integrator 76, and an adder 77.

The Kp calculation unit 72 is a part that executes a process of calculating the proportional gain Kp based on the deviation e. The Kp calculating unit 72 is set so that the proportional gain Kp output from the Kp calculating unit 72 monotonously increases as the deviation e increases. The Ki calculation unit 73 is a part that executes a process of calculating the integral gain Ki based on the deviation e. The Ki calculating unit 73 is set so that the integral gain Ki output from the Ki calculating unit 73 monotonously increases as the deviation e increases. Here, “monotonically increasing” includes (1) not only “monotonously increasing in a narrow sense” in which the integral gain Ki always increases with the increase of the deviation e but also (2) the integral gain Ki with the increase of the deviation e. "Monotonic increase in a broad sense" which increases stepwise (discretely) while holding constant at a predetermined interval is also included (note that "monotonic increase in a broad sense" is integrated with the increase of the deviation e The gain Ki may be referred to as “monotonous non-decreasing” because it increases without decreasing.) Hereinafter, the monotonous decrement is also included.

The multiplier 74 is a part that executes the process of multiplying the deviation e by the integral gain Ki, the multiplier 75 is a part that executes the process of multiplying the deviation e by the proportional gain Kp, and the integrator 76 is a multiplier 74. It is a part which performs processing which accumulates a time change of an operation result of. The adder 77 executes a process of adding the calculation result of the multiplier 75 and the calculation result of the integrator 76, and outputs the calculation result to the correction unit 78.

The correction unit 78 is a part that converts the assist torque to zero and outputs it when the value of the assist torque Tm output from the adder 77 is negative, and the adder 77 when the assist torque Tm is equal to or greater than zero. The value output from is output to the minimum value selector 57 as it is. The reason for converting negative values to zero is as follows. That is, when the actual rotational speed of the engine 1 overshoots, the assist torque amount Tm may be negative, but the calculation of the negative assist torque amount Tm is to drive the motor generator 2 as a generator. Means that the torque (power generation torque) was calculated. However, in the present embodiment, the power generation torque is calculated based on the remaining charge amount of the power storage device 10, and the calculation of the power generation torque based on the rotational speed deviation e is unnecessary as described later.

As described above, in the assist torque calculation unit 70, when the assist torque Tm calculated by the PI control unit 71 is greater than or equal to zero, the gains (Kp, Ki) monotonously increase in accordance with the increase in the rotational speed deviation e. Due to the map setting of the Kp calculating unit 72 and the Ki calculating unit 73, the assist torque Tm is set so as to increase monotonously as the rotational speed deviation e increases.

In addition, the first limit torque calculation unit 60 calculates the absorption torque limit amount Tp1 based on the deviation e, and the absorption torque limit amount Tp1 output from the PI control unit 61 for the hydraulic pump 3 properly. And a correction unit 68 that corrects from the viewpoint of control. The PI control unit 61 includes a proportional gain (Kp) computing unit 62, an integral gain (Ki) computing unit 63, a multiplier 64, a multiplier 65, an integrator 66, and an adder 67.

The Kp calculating unit 62 is a part that executes a process of calculating the proportional gain Kp based on the deviation e. The Kp calculating unit 62 is set so that the proportional gain Kp output from the Kp calculating unit 62 monotonously decreases as the deviation e increases. The Ki calculation unit 63 is a part that executes a process of calculating the integral gain Ki based on the deviation e. The Ki calculating unit 63 is set so that the integral gain Ki output from the Ki calculating unit 63 monotonously decreases as the deviation e increases.

The multiplier 64 is a part that executes the process of multiplying the deviation e by the integral gain Ki, the multiplier 65 is a part that executes the process of multiplying the deviation e by the proportional gain Kp, and the integrator 66 is a multiplier 64. It is a part which performs processing which accumulates a time change of an operation result of. The adder 67 executes a process of adding the calculation result of the multiplier 65 and the calculation result of the integrator 66, and outputs the calculation result to the correction unit 68.

The correction unit 68 is a part that converts the absorption torque restriction amount Tp1 to zero and outputs the absorption torque restriction amount Tp1 when the value of the absorption torque restriction amount Tp1 output from the adder 67 is negative, and the absorption torque restriction amount Tp1 is zero or more. In this case, the value output from the adder 67 is output to the adder 52 as it is. The reason for converting negative values to zero is as follows. That is, when the actual rotational speed of the engine 1 overshoots, the absorption torque limit amount Tp1 may become negative, but in this case, the restriction of the absorption torque (pump power) of the hydraulic pump 3 is unnecessary. is there.

As described above, in the first limit torque calculation unit 60, when the absorption torque limit amount Tp1 calculated by the PI control unit 61 is greater than or equal to zero, the gains (Kp, Ki) are adjusted according to the increase in the rotational speed deviation e. Due to the map setting in the Kp computing unit 62 and the Ki computing unit 63 in which the 単調 decreases monotonically, the absorption torque limit amount Tp1 is set to decrease monotonically as the rotational speed deviation e increases.

FIG. 6 is a view schematically showing the magnitude relationship between the magnitude of the assist torque amount Tm and the magnitude of the absorption torque limit amount Tp1 in the present embodiment. According to the control device 8 according to the present embodiment having the above configuration, the ratio of the assist torque amount Tm to the absorption torque limit amount Tp1 changes according to the rotation speed deviation e. The assist torque amount Tm monotonously increases with the increase of the rotational speed deviation e, and the absorption torque limit amount Tp1 monotonously decreases with the increase of the rotational speed deviation e. Therefore, as shown in FIG. And the absorption torque limit amount Tp1 intersect at one point. The intersection point is configured to coincide with the set value N1 (N1 = e1) by the setting of the maps in the

Kp computing units

62 and 72 and the

Ki computing units

63 and 73. Thereby, the ratio of the magnitude of the assist torque amount Tm to the magnitude of the absorption torque limit amount Tp1 is set such that the magnitude of the absorption torque limit amount Tp1 is larger when e <N1 where it is determined that a lag-down has occurred. When it is determined that acceleration has occurred, e ≧ N1, the magnitude of the assist torque amount Tm is set larger. At this time, the

Kp computing units

62 and 72 and the

Ki computing units

63 and 73 function as a determination unit for determining whether the cause of the rotation speed deviation e is acceleration or lag-down.

Returning to FIG. 5, the remaining charge calculation unit 54 is a part that executes a process of calculating the remaining charge (SOC) of the power storage device 10. As a method of calculating the remaining charge amount, there is a method of calculating the remaining charge amount based on information such as current, voltage and temperature detected by the current sensor 11, the voltage sensor 12, and the temperature sensor 13.

Maximum motor power calculation unit 55 is a part that executes processing for calculating the maximum assist power (maximum motor power) of motor generator 2 according to the remaining amount of power storage device 10 output from power storage amount calculation unit 54. is there. In the present embodiment, as shown in FIG. 5, the maximum power of motor generator 2 is set to zero or more when the remaining amount of power is equal to or greater than predetermined value S1, and assist is provided according to the increase in remaining amount of power. The power is set to increase. On the other hand, when the remaining charge amount is less than S1, it is set negative. The power of the motor generator 2 "negative" indicates that the motor generator 2 is driven as a generator, and the power storage device 10 is charged by the power generation of the motor generator 2 when the storage amount is less than S1. The power value calculated by the maximum motor power calculation 55 is output to the divider 56 and the limit torque calculation unit 80. When the remaining charge amount is less than S1 (during power generation), the value calculated by maximum motor power calculation unit 55 may be used as power generation request power, and the adder 42 shown the value in FIG. It may be output to In the graph in FIG. 5 relating to the maximum motor power calculation unit 55, the maximum motor power monotonously increases when the storage residual amount is S1 or more, but the storage residual amount has a predetermined value S2 (S2> S1 The above setting may be used to keep the maximum motor power constant.

The divider 56 divides the power value output from the maximum motor power calculation unit 55 by the actual number of revolutions of the engine 1 (which can be calculated from the output value of the number-of-rotations sensor), thereby dividing the maximum value of the torque of the motor generator 2 It is a part to calculate. That is, the divider 56 functions as a torque calculator. The torque calculated by the divider 56 is output to the minimum value selector 57.

The minimum value selector 57 compares the assist torque amount Tm output from the assist torque calculation unit 70 with the torque maximum value output from the divider 56, and uses the smaller one as the torque command value of the motor generator 2 as an inverter. Output to 9A (motor control unit). Thus, the inverter 9A controls the motor generator 2 based on the torque command. When the remaining charge amount of power storage device 10 is less than S1, the output of power calculation unit 55 has a negative value, and the output of divider 56 also has a negative value. Therefore, in the present embodiment, even if a positive assist torque amount Tm is output by the assist torque calculation unit 70 due to the presence of the deviation e, the minimum value selector 57 always selects the negative value output from the divider 56. Power generation is to be prioritized over engine assist.

By the way, when the pump power exceeding the sum of the power calculated by the maximum motor power calculation unit 55 and the maximum power of the engine 1 is required, the power supplied to the hydraulic pump 3 is insufficient. It is predicted that the actual rotational speed will decrease. Therefore, in order to prevent such a lag-down, in the present embodiment, the control for reducing the torque corresponding to the insufficient power (the absorption torque limit amount Tp2 of the hydraulic pump 3) from the absorption torque of the hydraulic pump 3 is limited torque calculation unit 80 It is going on. When the storage amount of power storage device 10 is equal to or greater than the set value S1, the absorption torque limit amount Tp2 of hydraulic pump 3 is increased as the storage amount of charge decreases. By this processing, without waiting for the decrease in the actual rotational speed of the engine 1 (that is, without waiting for the occurrence of a lag-down), the storage torque of the hydraulic pump 3 is limited by referring to the remaining charge amount of the power storage device 10 (Tp2) can be increased or decreased. In order to realize the function, the limit torque calculation unit 80 is a part that calculates the absorption torque limit amount Tp2 according to the remaining charge amount, and the adder 81, the subtractor 82, the correction unit 83, and the divider It has 84.

The adder 81 is a part that calculates the sum of the power of the motor generator 2 output from the maximum motor power calculation unit 55 and the maximum power of the engine 1, and outputs the calculation result to the subtractor 82.

The subtractor 82 is a part that executes a process of subtracting the power output from the adder 81 from the pump power requirement output from the pump power requirement calculator 41 (FIG. 4). Output. The fact that the calculated value of the subtractor 82 is positive indicates that the pump request power is excessive with respect to the power of the engine 1 and the motor generator 2. In this case, the actual rotational speed of the engine 1 decreases due to lag-down. Indicates to do. When the power of the motor generator 2 output from the maximum motor power calculation unit 55 is negative, the power (power required to generate power) is treated as a load on the engine 1 together with the power required for the pump in the subtractor 82. .

If the output from the subtractor 82 is greater than or equal to zero, the correction unit 83 outputs the value as it is to the divider 84. The output to the divider 84 at this time corresponds to the insufficient power. When the storage amount of the storage device 10 is equal to or greater than the set value S1, the insufficient power (the absorption torque limitation amount of the hydraulic pump 3) increases as the storage amount decreases. On the other hand, if the output from the subtractor 82 is negative, it indicates that the power is not insufficient, so zero is output to the divider 84. In the latter case, the absorption torque limitation of the hydraulic pump 3 by the limitation torque calculation unit 80 is not finally executed.

The divider 84 divides the power value output from the correction unit 83 by the actual number of revolutions of the engine 1 (which can be calculated from the output value of the number-of-rotations sensor) to calculate the absorption torque limit amount Tp2 (amount of torque shortage). Part of the That is, the divider 84 functions as a torque calculator. The absorption torque limit amount Tp2 calculated by the divider 84 is output to the adder 52.

The adder 52 executes a process of adding the absorption torque limit amount Tp1 output from the limit torque calculation unit 60 and the absorption torque limit amount Tp2 output from the limit torque calculation unit 80, and calculates the calculation result as a capacity calculation. Output to the part 53. Therefore, the value (Tp1 + Tp2) calculated by the adder 52 becomes the final absorption torque limit amount of the hydraulic pump 3.

The displacement calculation unit 53 calculates the target displacement of the hydraulic pump 3 based on the total value (Tp1 + Tp2) of the torque limitation amount output from the adder 52 and the discharge pressure of the hydraulic pump 3 obtained from the output of the pressure sensor 22. It is a part which performs the process to be performed and outputs the capacity | capacitance instruction | command based on the calculated target capacity | capacitance to the regulator 14 (electromagnetic proportional valve 15). Thus, the displacement of the hydraulic pump 3 is controlled based on the calculation results of the limit torque calculation units 60 and 80.

According to the working machine according to the present embodiment configured as described above, when a deviation e between the target number of revolutions of the engine 1 and the actual number of revolutions occurs, the magnitude of the deviation e is the set value e1 (N1) If it is less than this, it is determined that the cause of occurrence of the deviation is "lag down (engine lag down)", and the hydraulic pressure pump is larger than the assist torque amount Tm of the motor generator 2 by the limit torque calculation unit 60 and the assist torque calculation unit 70. The magnitude of the absorption torque limit amount Tp1 of 3 is set large (| Tm | <| Tp1 |), and the power of the hydraulic pump 3 is mainly limited.

In general, the engine is operating at maximum power at the time of lag-down, and if the assist power by the motor generator is mainly used to recover from the lag-down, energy required to assist the motor generator increases and power consumption is consumed. The amount tends to increase. For this reason, when a battery (power storage device) is provided as a power source to the motor generator, the necessity of driving the motor generator as an electric generator as an engine increases, and the fuel consumption may increase. On the other hand, when the generation and charge by the generator motor are not performed, the time during which the motor generator can assist the engine decreases. On the other hand, if control is performed as in the present embodiment, the power of the hydraulic pump 3 is mainly limited at the time of lag-down, so that it is possible to promptly return to the target rotation speed while suppressing excessive power consumption.

Also, there is a method of determining the assist power of the motor generator according to the magnitude of the rotational speed deviation of the engine, but in this method, power generation is performed while the engine is operating at or near maximum power. The amount of work of the work machine is extremely dependent on the amount of charge of the storage device. However, according to the present embodiment, at the time of lag-down, since the power of hydraulic pump 3 is mainly limited to cope with this, the opportunity to assist with large power continuously by motor generator 2 is limited. It is suppressed that the charge amount of the battery decreases in a short time. Therefore, it can be avoided that the amount of work of the work machine is extremely dependent on the charge amount of power storage device 10, and stable operation can be continued.

On the other hand, according to the work machine according to the present embodiment configured as described above, when a deviation e between the target speed of the engine 1 and the actual speed occurs, the magnitude of the deviation e is the set value e1 ( If it is N1) or more, the cause of the deviation is determined to be "acceleration" of the engine 1, and the motor generator is more than the size of the absorption torque limit amount Tp1 of the hydraulic pump 3 by the limit torque calculation unit 60 and the assist torque calculation unit 70. The magnitude of the assist torque amount Tm of 2 is set to be large (| Tm |> | Tp1 |), and the engine assist by the motor generator 2 is mainly executed.

Generally, at the time of engine acceleration, the engine power is often increased by increasing the engine speed and the like because the required power of the hydraulic pump is increased. Although there is a method of limiting the pump power according to the magnitude of the rotational speed deviation of the engine, in this method, the pump power is excessively limited due to the rotational speed deviation generated at the time of acceleration, and the operability may be deteriorated. On the other hand, in the present embodiment, the engine 1 is mainly accelerated by the assist power of the motor generator 2, and the power limitation of the hydraulic pump 3 is suppressed. Can be reached.

Therefore, according to the present embodiment, it is possible to quickly reach the target rotation speed without losing operability when the engine accelerates, and to quickly return to the target rotation speed while suppressing excessive power consumption at the time of lag-down.

Further, in the present embodiment, the control of absorption torque limit amount Tp2 according to the state of charge (charge amount) of power storage device 10 along with the change of the ratio of assist torque amount Tm and absorption torque limit amount Tp1 according to acceleration and lagdown. Is performed by the limit torque calculation unit 80.

In general, when the amount of charge of the power storage device is small, the motor generator can not assist, and thus if the pump request power exceeds the engine power, the engine rotational speed is lowered to cause an engine stall. For this type of problem, as in the conventional speed sensing, even if the pump power is limited when a decrease in engine rotational speed is detected, it is possible to avoid a reduction in engine rotational speed and engine stall.

On the other hand, when the absorption torque limit amount Tp2 is controlled based on the charge amount of the power storage device 10 as in the present embodiment, the pump power is limited before the reduction of the engine speed actually appears. Not only can the engine rotational speed decrease and engine stall be prevented, but also the deterioration of the operability due to the power reduction and the rotational speed fluctuation accompanying the engine rotational speed decrease can be suppressed. In particular, when the amount of charge of a secondary battery (power storage device) is very small and it is necessary to generate electric power by a motor generator to protect the secondary battery, it is compared with a conventional hydraulic working machine equipped with only a hydraulic actuator. Although the load on the engine is increased, according to the present embodiment, since the pump power can be rapidly limited, the above effect is remarkable.

In the above embodiment, “change of the ratio of the assist torque amount Tm to the absorption torque limit amount Tp1 by the limit torque calculation unit 60 and the assist torque calculation unit 70” and “the absorption torque limit amount by the limit torque calculation unit 80” Although the case of performing both of Tp2 has been described, each effect can also be obtained by including one of both of the “limiting torque computing unit 60 and the assist torque computing unit 70” and the “limiting torque computing unit 80”. In order to be demonstrated, either one of the two can be omitted appropriately.

Further, in the present embodiment, it is determined whether lagdown or acceleration is based on only the rotational speed deviation e. However, the rotational speed deviation e may be monitored by monitoring the target rotational speed of the engine 1 and changes in the actual rotational speed, etc. It may be determined with high accuracy whether the cause of the occurrence of the delay is lag down or acceleration, and the above control may be performed based on the determination result.

In the above embodiment, although the case of the hybrid hydraulic shovel was described as the working machine, except for the hydraulic shovel, as long as it is provided with a variable displacement hydraulic pump and a motor generator mechanically connected to the engine. It is applicable also to the work machine of.

The present invention is not limited to the above-described embodiment, and includes various modifications within the scope of the present invention. For example, the present invention is not limited to the one provided with all the configurations described in the above embodiment, but also includes one in which a part of the configuration is deleted. In addition, a part of the configuration according to an embodiment can be added to or replaced with the configuration according to another embodiment.

The configuration according to the control device 8 may be a program (software) in which each function according to the configuration of the control device is realized by being read and executed by an arithmetic processing unit (for example, a CPU). The information related to the program can be stored, for example, in a semiconductor memory (flash memory, SSD, etc.), a magnetic storage device (hard disk drive, etc.), a recording medium (magnetic disk, optical disc, etc.), and the like.

Moreover, although the control line and the information line showed what was understood to be required for description of the said embodiment in the description of each said embodiment, all the control lines and information lines which concern on a product are not necessarily shown. Does not necessarily indicate. In practice, it can be considered that almost all configurations are mutually connected.

DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Motor generator, 3 ... Variable displacement hydraulic pump, 5 ... Hydraulic actuator, 8 ... Control apparatus, 9A, 9B ... Inverter, 14 ... Regulator, 16 ... Operation lever, 18a, 18b ... Pressure sensor, 19: motor (swing motor), 22: pressure sensor, 32: pilot pump, 41: pump request power operation unit, 43: target rotational speed operation unit, 53: capacity operation unit, 54: remaining charge operation unit, 55: Maximum motor power operation unit 57: minimum value selector 60: first limit torque operation unit 70: assist torque operation unit 80: second limit

torque operation unit

91, 92, 93 hydraulic cylinder 95, 96 ... hydraulic motor, 100a ... boom, 100b ... arm, 100c ... bucket (attachment), 100d ... upper revolving unit, 100e ... lower traveling unit

Claims

With the engine,
A motor generator for transmitting torque between the engine and the engine;
A variable displacement hydraulic pump driven by at least one of the engine and the motor generator;
A hydraulic actuator driven by pressure oil discharged from the hydraulic pump;
A motor control unit configured to control an assist torque amount applied to the engine by the motor generator based on the target rotation speed and the actual rotation speed of the engine;
And a pump control unit configured to control an absorption torque limit amount of the hydraulic pump based on the target rotation speed and the actual rotation speed of the engine.
When it is determined that the engine is in a lag-down state based on the target engine speed and the actual engine speed, the absorption torque limit amount is set larger than the assist torque amount.
A working machine characterized in that the assist torque amount is set larger than the absorption torque limit amount when it is determined that the engine is accelerated based on the target engine speed and the actual engine speed.
In the work machine according to claim 1,
When the magnitude of the deviation between the target rotational speed of the engine and the actual rotational speed is greater than or equal to the set value N1 is determined as acceleration of the engine, and when the magnitude of the deviation is less than the set value N1 is lagdown of the engine and The apparatus further comprises a determination unit for determining
A working machine, wherein the motor control unit and the pump control unit limit the assist torque amount and the absorption torque limit amount based on the determination result of the determination unit.
In the working machine according to claim 2,
It further comprises a power storage device in which the power supplied to the motor generator is stored,
The working machine, wherein the pump control unit increases the absorption torque limitation amount of the hydraulic pump as the remaining charge amount decreases when the remaining charge amount of the power storage device is equal to or greater than a set value S1.
In the working machine according to claim 2 or 3,
The target rotational speed is set to discretely increase stepwise as the sum of the required power of the pump and the required power of generation of the motor generator increases.
The amount of increase in the target speed corresponding to the height of each step of the step is a constant value,
A working machine characterized in that the constant value and the set value N1 coincide with each other.
With the engine,
A motor generator for transmitting torque between the engine and the engine;
A variable displacement hydraulic pump driven by at least one of the engine and the motor generator;
A hydraulic actuator driven by pressure oil discharged from the hydraulic pump;
A motor control unit configured to control an assist torque amount applied to the engine by the motor generator based on the target rotation speed and the actual rotation speed of the engine;
A pump control unit configured to control an absorption torque limit amount of the hydraulic pump based on values of the target rotation speed and the actual rotation speed of the engine;
And a power storage device for storing power supplied to the motor generator.
The working machine, wherein the pump control unit increases the absorption torque limitation amount of the hydraulic pump as the storage amount decreases when the storage amount of the storage device is equal to or greater than a set value S1.