WO2016027463A1 - Hydraulic pump drive system - Google Patents

Hydraulic pump drive system Download PDF

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Publication number
WO2016027463A1
WO2016027463A1 PCT/JP2015/004127 JP2015004127W WO2016027463A1 WO 2016027463 A1 WO2016027463 A1 WO 2016027463A1 JP 2015004127 W JP2015004127 W JP 2015004127W WO 2016027463 A1 WO2016027463 A1 WO 2016027463A1
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WO
WIPO (PCT)
Prior art keywords
torque
injection amount
fuel injection
change
actual
Prior art date
Application number
PCT/JP2015/004127
Other languages
French (fr)
Japanese (ja)
Inventor
博英 松嶋
孝志 陵城
英泰 村岡
陽治 弓達
和也 岩邊
Original Assignee
川崎重工業株式会社
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Publication date
Application filed by 川崎重工業株式会社 filed Critical 川崎重工業株式会社
Publication of WO2016027463A1 publication Critical patent/WO2016027463A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K6/00—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00
    • B60K6/20—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs
    • B60K6/42—Arrangement or mounting of plural diverse prime-movers for mutual or common propulsion, e.g. hybrid propulsion systems comprising electric motors and internal combustion engines ; Control systems therefor, i.e. systems controlling two or more prime movers, or controlling one of these prime movers and any of the transmission, drive or drive units Informative references: mechanical gearings with secondary electric drive F16H3/72; arrangements for handling mechanical energy structurally associated with the dynamo-electric machine H02K7/00; machines comprising structurally interrelated motor and generator parts H02K51/00; dynamo-electric machines not otherwise provided for in H02K see H02K99/00 the prime-movers consisting of electric motors and internal combustion engines, e.g. HEVs characterised by the architecture of the hybrid electric vehicle
    • B60K6/48—Parallel type
    • B60K6/485—Motor-assist type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L50/00—Electric propulsion with power supplied within the vehicle
    • B60L50/10—Electric propulsion with power supplied within the vehicle using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines
    • B60L50/16—Electric propulsion with power supplied within the vehicle using propulsion power supplied by engine-driven generators, e.g. generators driven by combustion engines with provision for separate direct mechanical propulsion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/06—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of combustion engines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/04—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units
    • B60W10/08—Conjoint control of vehicle sub-units of different type or different function including control of propulsion units including control of electric propulsion units, e.g. motors or generators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W20/00—Control systems specially adapted for hybrid vehicles
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D29/00—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto
    • F02D29/04—Controlling engines, such controlling being peculiar to the devices driven thereby, the devices being other than parts or accessories essential to engine operation, e.g. controlling of engines by signals external thereto peculiar to engines driving pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/62—Hybrid vehicles
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

Definitions

  • the present invention relates to a drive system for a hydraulic pump that rotates a rotating shaft by an engine and an electric motor to drive the hydraulic pump.
  • Construction machines and the like are provided with a hydraulic pump, and a hydraulic actuator such as a hydraulic cylinder is operated by pressure oil discharged from the hydraulic pump to move an arm, a boom, and the like.
  • the hydraulic pump is connected to the engine and the electric motor via a rotating shaft, and is rotated by the engine and the electric motor.
  • a construction machine configured in this way, for example, a construction machine disclosed in Patent Document 1 is known.
  • the engine is controlled by a control device so that the engine speed becomes a rotation speed command.
  • the hydraulic pump such as when a hydraulic actuator is driven
  • the engine speed is increased.
  • the number drops.
  • the control device moves the electric motor to assist the engine power.
  • the engine speed is kept constant (specifically, the engine speed command).
  • the control device reduces the amount of charge of the power storage device that supplies electric power to the motor after the motor is operated, and increases the deviation between the charge amount and the charge amount command, while limiting the rate of time change and the target torque of the engine Is supposed to increase.
  • the torque adjustment by the electric motor is not performed until the deviation actually occurs (in other words, the torque adjustment by the electric motor is performed after the deviation is actually calculated).
  • the torque adjustment may not be performed immediately and the engine speed may decrease excessively.
  • the present invention provides a hydraulic pump operating system that can be assisted by an electric motor so that the rotational speed of the engine does not decrease excessively.
  • a hydraulic pump drive system includes an engine that rotationally drives a rotary shaft of a hydraulic pump, an electric motor that can assist in the rotational drive of the rotary shaft, and a rotational speed sensor that detects the rotational speed of the rotary shaft.
  • a control device for controlling the electric motor comprising: a target fuel injection amount calculation unit; an injection amount restriction unit; an actual torque calculation unit; a target torque calculation unit; a differential torque calculation unit; A control unit, wherein the target fuel injection amount calculation unit calculates a target fuel injection amount based on the actual rotational speed and the target rotational speed detected by the rotational speed sensor, and the injection amount restriction unit Has a function of increasing the actual fuel injection amount step by step up to the target fuel injection amount when calculating the actual fuel injection amount based on the target fuel injection amount.
  • a fuel injection amount is determined, and the actual torque calculation unit calculates an actual torque output from the engine based on the actual rotation speed and the actual fuel injection amount determined by the injection amount limiting unit;
  • the target torque calculation unit calculates a target torque to be applied to the rotating shaft based on the actual rotational speed and the target fuel injection amount, and the differential torque calculation unit calculates the actual torque with respect to the target torque.
  • the deficient differential torque is calculated, and the drive control unit controls the electric motor to output the differential torque.
  • the output torque of the engine becomes insufficient by limiting the time change rate of the actual fuel injection amount, but the insufficient output torque is calculated in advance as a differential torque.
  • the torque output from the entire hydraulic pump drive system can be brought close to the target torque even if the actual fuel injection amount is limited, and the torque output from the entire hydraulic pump drive system can be reduced.
  • the decrease can be suppressed.
  • the amount of change in output torque due to the time rate of change being limited is estimated in advance, and the shortage of torque is output to the motor to deal with it. It is possible to suppress an excessive decrease in the engine speed as compared with the case where the torque is adjusted according to the number deviation. Thereby, it is possible to suppress a decrease in fuel consumption of the engine due to an excessive decrease in the engine speed.
  • the injection amount limiting unit may set the target fuel injection amount as the actual fuel injection amount when the target fuel injection amount is decreased.
  • the actual fuel injection amount is calculated by the injection amount limiting unit, and when the target fuel injection amount is decreasing, the target fuel injection amount is set as the actual fuel injection amount.
  • the actual torque and the target torque calculated by each of the actual torque calculation unit and the target torque calculation unit are the same or substantially the same, and the differential torque calculated by the differential torque calculation unit is zero. Therefore, it is possible to eliminate regeneration of the electric motor using the output torque of the engine, and it is possible to improve the fuel consumption of the engine.
  • the injection amount limiting unit when the target fuel injection amount is increasing, changes the proportion in proportion to the elapsed time.
  • the actual fuel injection amount may be increased stepwise based on a change rule.
  • the injection amount limiting unit delays a primary delay with respect to an elapsed time.
  • the actual fuel injection amount may be changed stepwise based on a change rule.
  • the control device includes a torque change estimation unit and a change torque calculation unit, and the torque change estimation unit is configured to output the engine based on the actual fuel injection amount and the actual rotational speed. Estimating a change amount of torque, the change torque calculating unit calculates a change torque so as to assist the rotational drive of the rotary shaft based on the change amount of the output torque calculated by the torque change estimating unit; The drive control unit may control the electric motor to output a torque obtained by adding the change torque to the differential torque.
  • the change amount (decrease amount) of the output torque due to the change in the actual fuel injection amount is estimated in advance, and the change torque to be assisted is calculated based on the estimated change amount.
  • the calculated change torque is output from the electric motor with differential torque added.
  • the output torque of the engine can be assisted by the electric motor, and when the output torque changes, the change can be assisted by the electric motor.
  • the above configuration causes the output torque due to the change in the actual fuel injection amount. A decrease and an excessive decrease in the engine speed can be prevented. Thereby, the fall of operativity by the fall of the hydraulic pump discharge flow accompanying the engine speed falling too much can be suppressed.
  • the torque change estimation unit estimates a rate of change of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and the actual torque calculated by the actual torque calculation unit The amount of change in the output torque may be calculated based on the rate of change.
  • the change in the actual fuel injection amount affects the combustion state not only at the time of combustion immediately after the supply but also over several subsequent combustions. That is, the influence on the combustion state due to the change in the actual fuel injection amount is reduced by passing the number of combustions instead of the time, and the combustion state of the engine changes according to the number of combustions (that is, the number of revolutions) rather than the time. .
  • the rate of change of the output torque for each unit revolution of the engine with respect to the change of the actual fuel injection amount is calculated, and the amount of change of the output torque for each unit revolution is calculated based on this rate of change and the actual torque. It can be calculated.
  • the amount of change in output torque is calculated not in time units but in rotation speed units, it is possible to estimate the decrease in output torque more accurately than in the case of calculation in time units.
  • the engine can be assisted based on the amount of change in the output torque, so that the engine speed can be prevented from excessively decreasing.
  • the torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed.
  • the pseudo-differential calculation unit calculates a rate of change of the actual fuel injection amount per unit revolution of the engine by pseudo-differentiation using the time constant calculated by the time-constant calculation unit, and the real fuel injection
  • the torque change estimation unit may estimate the amount of change in the output torque per unit revolution of the engine based on the rate of change in the amount.
  • the change torque calculation unit may set the change torque to zero when the change rate of the actual fuel injection amount is less than zero.
  • the drive system for the hydraulic pump includes an engine that rotationally drives a rotary shaft of the hydraulic pump, an electric motor that can assist the rotational drive of the rotary shaft, and a rotational speed sensor that detects the actual rotational speed of the rotary shaft.
  • a control device for controlling the movement of the electric motor wherein the control device includes an actual fuel injection amount calculation unit, a torque change estimation unit, an assist torque calculation unit, and a drive control unit,
  • the actual fuel injection amount calculation unit calculates an actual fuel injection amount based on the actual rotational speed and the target rotational speed
  • the torque change estimation unit calculates the actual fuel injection amount based on the actual fuel injection amount and the actual rotational speed.
  • An amount of change in engine output torque is estimated, the change torque calculation unit calculates a change torque that assists the rotational drive of the rotating shaft based on the amount of change in the output torque, and the drive control unit Torque output And controls the electric motor so that.
  • the change amount (decrease amount) of the output torque due to deterioration of the combustion state of the engine due to the change in the actual fuel injection amount should be estimated in advance, and assisted based on the estimated change amount Calculate the change torque.
  • the calculated change torque is output from the electric motor.
  • the output torque of the engine can be assisted by the electric motor, and when the output torque changes, the change can be assisted by the electric motor.
  • the above configuration causes a decrease in output torque and excessive rotation speed. Can be prevented.
  • the fall of operativity by the fall of the discharge flow volume of the hydraulic pump accompanying rotation number falling too much can be suppressed.
  • the control device includes an actual torque calculation unit, and the actual torque calculation unit is output from the engine based on the actual rotation speed detected by the rotation speed sensor and the actual fuel injection amount.
  • the torque change estimating unit estimates a change rate of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and based on the actual torque and the change rate. Then, the amount of change in the output torque may be calculated.
  • the change rate of the output torque for each unit speed with respect to the change in the actual fuel injection amount is calculated, and the change amount of the output torque for each unit speed is calculated based on the change rate and the actual torque. can do.
  • the amount of change in the output torque is calculated not in time units but in rotation speed units, it is possible to estimate the torque drop more accurately than in the case of calculation in time units.
  • the engine can be assisted based on the amount of change in the output torque, so that the engine speed can be prevented from excessively decreasing.
  • the torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed. And the pseudo-differential calculation unit calculates the rate of change of the actual fuel injection amount per unit rotational speed of the engine using pseudo-differentiation by pseudo-differentiation using the time constant calculated by the time constant calculation unit.
  • the torque change estimation unit may estimate the change amount of the output torque per unit revolution of the engine based on the change rate of the actual fuel injection amount.
  • the motor when a load is applied to the hydraulic pump and the engine speed decreases, the motor can assist the engine speed so that the engine speed does not decrease excessively.
  • FIG. 1 is a block diagram showing a hydraulic pump drive system according to an embodiment of the present invention.
  • FIG. 2 is a functional block diagram illustrating functions of a control device provided in the hydraulic pump drive system of FIG. 1 as blocks.
  • FIG. 3 is a functional block diagram illustrating a part of the control device of FIG. 2 in more detail. It is a graph which shows the time-dependent change of various values when the hydraulic pump drive system of FIG. 1 is driven. It is a graph which shows the time-dependent change of various values when the hydraulic pump drive system of other embodiment is driven.
  • Construction machines are equipped with various attachments such as buckets, loaders, blades and hoisting machines, and are moved by hydraulic actuators such as hydraulic cylinders and hydraulic motors (electro-hydraulic motors).
  • a hydraulic excavator that is a kind of construction machine includes a bucket, an arm, and a boom, and can perform operations such as excavation while moving these three members.
  • Each of the bucket, arm, and boom is provided with hydraulic cylinders 11 to 13, and the bucket, arm, and boom are moved by supplying pressure oil to each cylinder 11-13.
  • the hydraulic excavator has a traveling device, and a revolving body is mounted on the traveling device so as to be capable of turning.
  • a boom is attached to the revolving structure so as to be swingable in the vertical direction.
  • a hydraulic turning motor 14 is attached to the turning body, and the turning body is turned by supplying pressure oil to the turning motor 14.
  • a hydraulic traveling motor 15 is attached to the traveling device, and the traveling device 15 moves forward or backward by supplying pressure oil to the traveling motor 15.
  • the hydraulic actuators 11 to 15 (that is, the hydraulic cylinders 11 to 13 and the hydraulic motors 14 and 15) are connected to the hydraulic supply device 16 and are operated by receiving the supply of pressure oil from the hydraulic supply device 16. Yes.
  • the hydraulic pressure supply device 16 has a hydraulic pump 17 and a control valve 18.
  • the hydraulic pump 17 is a swash plate pump, for example, and has a rotating shaft 17a, and discharges pressure oil by rotating the rotating shaft 17a.
  • the discharged pressure oil is guided to the control valve 18, and the control valve 18 controls the flow of the discharged pressure oil.
  • the hydraulic excavator is provided with a plurality of operating tools (for example, operating levers and operating buttons) in association with the hydraulic actuators 11 to 15, and the control valve 18 is operated when the operating tools are operated.
  • Pressure oil is allowed to flow through the hydraulic actuators 11 to 15 corresponding to the operation tools. By flowing the pressure oil in this manner, the hydraulic actuators 11 to 15 are operated according to the operation of the operation tool, and the bucket, arm, boom, and the like are moved.
  • the rotary shaft 17a of the hydraulic pump 17 is connected to the hydraulic pump drive system 1, and the rotary shaft 17a is driven to rotate by the hydraulic pump drive system 1.
  • the hydraulic pump drive system 1 is a hybrid drive system including an engine E and an electric motor 20, and both the engine E and the electric motor 20 are connected to a rotating shaft 17 a of the hydraulic pump 17.
  • the engine E is, for example, a diesel engine having a plurality of cylinders, and a fuel injection device 21 is provided in association with each cylinder.
  • the fuel injection device 21 includes, for example, a fuel pump and an electromagnetic control valve, and injects an amount of fuel corresponding to an input injection command into the combustion chamber of the corresponding cylinder.
  • the engine E burns the fuel injected from the fuel injection device 21 and reciprocates a piston (not shown) to rotate the rotating shaft 17a and discharge the hydraulic oil from the hydraulic pump 17.
  • the engine E is a diesel engine.
  • the engine E is not necessarily a diesel engine and may be a gasoline engine.
  • the rotating shaft 17a is provided with an electric motor 20 that assists in driving the engine E.
  • the electric motor 20 is an AC motor, for example, and is connected to the inverter 22.
  • the inverter 22 which is a driving device is connected to a battery (not shown), and converts a direct current supplied from the battery into an alternating current and supplies the alternating current to the electric motor 20. Further, the inverter 22 supplies an alternating current having a frequency and voltage according to the input torque command to the electric motor 20 so that the torque corresponding to the torque command (assist torque described later) is output from the electric motor 20 to the rotating shaft 17a. It has become.
  • a rotation speed sensor 23 is attached to the rotation shaft 17a.
  • the rotation speed sensor 23 outputs a signal corresponding to the rotation speed of the rotation shaft 17a.
  • the rotation speed sensor 23 is electrically connected to the control device 30 together with the inverter 22 and the electromagnetic control valve of the fuel injection device 21.
  • the control device 30 calculates the actual rotational speed of the rotating shaft 17a based on the signal input from the rotational speed sensor 23, and calculates the difference between the calculated actual rotational speed and the target rotational speed.
  • the target rotational speed is a rotational speed that is input from an input means (a dial, a button, a touch panel, or the like) or is set in advance.
  • the control device 30 calculates a target fuel injection amount to be injected from the fuel injection device 21 based on the difference between the actual rotational speed and the target rotational speed. Further, the control device 30 calculates an actual fuel injection amount by a method to be described later based on the target fuel injection amount, and causes the fuel injection device 21 to inject this actual fuel injection amount.
  • the control device 30 calculates the actual rotation speed and the target fuel injection amount at predetermined intervals. Further, the control device 30 assists the engine E by driving the electric motor 20 when only the torque from the engine E is insufficient.
  • the function of the control device 30 will be described in more detail with reference to FIGS. 2 and 3.
  • the control device 30 has a functional part that calculates various values (a first assist torque and a second assist torque described later). If the functional part that calculates various values is divided into blocks, the target fuel injection will be described.
  • An amount calculation unit 38, a target torque calculation unit 31, an injection amount restriction unit 32, an actual torque calculation unit 33, and a first assist torque calculation unit 34 are provided.
  • the target fuel injection amount calculation unit 38 calculates a target fuel injection amount to be injected from the fuel injection device 21 based on the difference between the actual rotational speed and the target rotational speed.
  • the target torque calculator 31 calculates the target torque using the target torque map.
  • the target torque map is a map in which the target torque to be output by the entire hydraulic pump drive system 1 is associated with the target fuel injection amount and the actual rotational speed.
  • the target torque calculation unit 31 calculates the target torque from the target torque map based on the calculated target fuel injection amount and actual rotation speed.
  • the target fuel injection amount calculated by the target fuel injection amount calculation unit 38 is used for the injection amount restriction unit 32 to calculate the actual fuel injection amount to be actually injected by the fuel injection device 21.
  • the injection amount limiting unit 32 (actual fuel injection amount calculation unit) has a rate limit function with an increase rate limitation and without a decrease rate limitation, and the actual fuel injection amount based on the target fuel injection amount by this rate limit function. Is calculated. More specifically, when the target fuel injection amount increases and the increase rate of the target fuel injection amount exceeds a predetermined value, the injection amount limiting unit 32 sets the change rate or the change amount based on a predetermined change rule. The actual fuel injection amount is changed stepwise up to the target fuel injection amount while limiting. On the other hand, when the target fuel injection amount decreases, the injection amount limiting unit 32 sets the target fuel injection amount as the actual fuel injection amount without limiting the reduction rate.
  • the injection amount restriction unit 32 internally holds (that is, stores) the target fuel injection amount calculated by the target fuel injection amount calculation unit 38, and calculates immediately after the held target fuel injection amount. The target fuel injection amount thus made is compared.
  • the target fuel injection amount immediately after the held target fuel injection amount is small, that is, when the target fuel injection amount is decreasing, the target fuel injection amount is calculated as the actual fuel injection amount.
  • the rate of increase is It is determined whether or not a predetermined value is exceeded. If it is less than the predetermined value, the target fuel injection amount is calculated as the actual fuel injection amount.
  • the actual fuel injection amount is gradually increased to the target fuel injection amount while limiting the increase rate based on a change rule that sets the increase rate to a predetermined value or less. That is, when it exceeds the predetermined value, the actual fuel injection amount is increased stepwise to the target fuel injection amount in proportion to the time based on a proportional constant equal to or less than the predetermined value.
  • the injection amount limiting unit 32 may be a filter, and may increase the target fuel injection amount based on, for example, a transfer function having a first-order lag element (that is, a lag element). The actual fuel injection amount calculated in this way is used together with the actual rotational speed in order to calculate the actual torque by the actual torque calculation unit 33.
  • the actual torque calculator 33 calculates the actual torque using the actual torque map.
  • the actual torque is an output torque output from the engine E when the fuel injection device 21 injects the actual fuel injection amount into the engine E.
  • the actual torque map is a map in which the actual torque is associated with the actual fuel injection amount and the actual rotational speed.
  • the actual torque calculation unit 33 calculates actual torque from the actual torque map based on the calculated actual fuel injection amount and actual rotation speed. In the present embodiment, the same map is used as the actual torque map and the target torque map. The calculated actual torque is used together with the target torque so that the first assist torque calculator 34 calculates the first assist torque to be output by the electric motor 20.
  • the first assist torque calculation unit 34 (difference torque calculation unit) is a shortage torque obtained by subtracting the actual torque from the target torque based on the actual torque calculated from one target fuel injection amount and the target torque. One assist torque (difference torque) is calculated. More specifically, the first assist torque calculator 34 subtracts the actual torque from the target torque, and calculates the first assist torque that is insufficient to generate the target torque from the hydraulic pump drive system 1.
  • control device 30 is configured to limit the rate of increase of the actual fuel injection amount when the target fuel injection amount suddenly increases. By limiting the increase rate in this way, it is possible to prevent deterioration of the combustion state of the engine E due to a rapid increase in the target fuel injection amount, and to improve fuel efficiency.
  • the first assist torque corresponding to the shortage is calculated in order to cause the motor 20 to output the shortage. is doing.
  • the control device 30 has a function of estimating the reduced output torque and calculating the second assist torque (change torque) so as to supplement the reduced output torque with the electric motor 20.
  • the control device 30 includes a torque change estimation unit 35, a second assist torque calculation unit 36, and a drive control unit 37 in order to calculate the second assist torque.
  • the torque change estimator 35 estimates the amount of change in torque output from the engine E based on the calculated actual rotational speed and actual fuel injection amount.
  • the combustion state becomes unstable due to a change in the actual fuel injection amount, and a response delay occurs in the output torque.
  • the combustion state of the engine E changes every revolution (in the case of a 4-stroke engine, every cycle of intake-compression-expansion-exhaust), and the unstable state of the combustion state improves as the number of combustions increases. Is done. Accordingly, as the actual rotational speed is larger, the number of combustions per unit time is increased, so that the instability of the combustion state of the engine E is improved more quickly, and the decrease in the torque of the engine E is reduced.
  • the torque change estimation unit 35 calculates a decrease in the output torque at every unit rotation speed (preferably every rotation) of the engine E. It is supposed to be.
  • the torque change estimating unit 35 numerically models the engine E using a transfer function including a pseudo-derivative described later to estimate the change in the output torque of the engine E, and further includes a first-order lag element included in the pseudo-differential. The time constant is changed according to the actual rotational speed. Thereby, it is possible to artificially calculate the output torque drop for each unit rotation speed.
  • the output torque characteristic of the engine E in which the response delay of the torque changes according to the actual rotational speed can be estimated by the above-described transfer function.
  • the torque change estimator 35 that estimates the amount of change in the output torque will be described in more detail below with reference to FIG. 3 in addition to FIG.
  • the torque change estimator 35 includes a time constant calculator 41, a pseudo-differential calculator 42, a torque change coefficient calculator 44, a torque change rate calculator 45, and a correction coefficient as functional parts for estimating a change in output torque.
  • a calculation unit 46 and a torque change amount calculation unit 47 are provided.
  • the time constant calculation unit 41 calculates a time constant from the actual rotational speed calculated by the control device 30 using the time constant map.
  • the time constant map is a map in which the time constant is associated with the actual rotation.
  • the correspondence between the time constant of the time constant map and the actual rotation is set based on data obtained from experiments and the like.
  • the displacement of the engine E, accessories (supercharger, EGR, etc.), and structure It depends on the pipe diameter and length.
  • the correspondence is different for each model of the engine E, and is set for each model of the engine E with reference to the experimental result.
  • the correspondence relationship may be set not only for each model but also for each individual.
  • the time constant calculated by the time constant calculating unit 41 is used together with the actual fuel injection amount by the pseudo-differential calculating unit 42 in order to calculate a differential value of the actual fuel injection amount.
  • the pseudo-differential calculation unit 42 calculates a differential value of the actual fuel injection amount by a transfer function obtained by numerically modeling the engine E.
  • the fuel injection amount corresponds to the torque
  • the differential value of the actual fuel injection amount corresponds to the rate of change of the torque. ing.
  • the pseudo differential operation unit 42 will be described in more detail.
  • the transfer function of the pseudo differential operation unit 42 includes a pseudo differential (also referred to as incomplete differentiation) including a first-order lag element. A differential value of the actual fuel injection amount is calculated using this transfer function.
  • the pseudo-differentiation, the Laplace variable and s, the differential gain and T D, when the constant is T time represented by the following formula (1).
  • the differential value of the actual fuel injection amount by the pseudo differential including the first-order lag element a value corresponding to the rate of change of the output torque considering the response delay due to the deterioration of the combustion state (that is, the actual fuel injection)
  • the differential value of the quantity is calculated.
  • the time constant calculated by the time constant calculation unit 41 is used as the time constant T of the first-order lag element included in the pseudo differentiation. That is, the pseudo-differential calculation unit 42 calculates the differential value of the actual fuel injection amount by changing the time constant every time it is calculated.
  • the rate of change of the output torque for each unit rotation speed (preferably for each rotation speed) is simulated. Can be calculated.
  • the differential value of the actual fuel injection amount calculated in this way corresponds to the rate of change per unit rotational speed of the output torque of the engine E, and the torque change coefficient described later is calculated by the torque change coefficient calculating unit 44. Used for.
  • the torque change coefficient calculation unit 44 calculates a torque change coefficient based on the differential value of the actual fuel injection amount calculated by the pseudo-differential calculation unit 42.
  • the torque change coefficient is a coefficient indicating how much the torque changes with respect to the actual torque.
  • the torque change coefficient calculating unit 44 first calculates the absolute value of the differential value of the actual fuel injection amount, and then uses the torque change coefficient map 44a shown in FIG. 3 to change the torque change from the absolute value of the differential value of the actual fuel injection amount. Calculate the coefficient.
  • the torque change coefficient map 44a is a map in which the absolute value of the differential value of the actual fuel injection amount is associated with the torque change coefficient. For example, the torque change coefficient map 44a is set so that the torque change coefficient increases as the absolute value of the differential value increases. Has been.
  • the correspondence between the absolute value of the differential value of the actual fuel injection amount of the torque change coefficient map 44a and the torque change coefficient is set based on data obtained from experiments or the like, and the time constant map and Similarly, it is set for each model of the engine E.
  • the correspondence relationship between the absolute value of the differential value of the actual fuel injection amount and the torque change coefficient is not necessarily the correspondence relationship as shown in FIG.
  • the torque change coefficient calculation unit 44 calculates a torque change coefficient based on the torque change coefficient map 44a and the absolute value of the differential value of the actual fuel injection amount, and the calculated torque change coefficient indicates the torque change rate as the torque change rate. It is used for calculation by the calculation unit 45.
  • the rate of change in torque is the ratio of torque that changes (specifically decreases) as the combustion state deteriorates, etc., relative to the actual torque that is output when fuel of the actual fuel injection amount is injected into the engine E. This is the value shown.
  • the torque change coefficient and the torque change rate basically correspond to each other, but the torque change coefficient is a value set so as to be uniquely derived from the absolute value of the differential value of the actual fuel injection amount.
  • the torque change rate takes into account not only the absolute value of the differential value of the actual fuel injection amount (that is, the torque change coefficient) but also the effects of the actual rotational speed and the actual fuel injection amount.
  • the torque change rate is corrected by the torque change coefficient calculated by the torque change coefficient calculating unit 44, and the correction coefficient for correction is calculated by the correction coefficient calculating unit 46. is doing.
  • the correction coefficient calculation unit 46 calculates a correction coefficient based on the actual rotational speed calculated by the control device 30 and the actual fuel injection amount calculated by the injection amount limiting unit 32.
  • the correction coefficient is a coefficient for correcting the torque change coefficient calculated by the torque change coefficient calculating unit 44 according to the actual rotational speed and the actual fuel injection amount. More specifically, the correction coefficient calculator 46 calculates the first correction coefficient from the actual rotational speed using the first correction coefficient map 46a as shown in FIG. 3, and the second correction coefficient as shown in FIG. A second correction coefficient is calculated from the actual fuel injection amount using the map 46b.
  • the first correction coefficient map 46a is a map in which the actual rotational speed and the first correction coefficient are associated with each other, and the second correction coefficient map 46b is in association with the actual fuel injection amount and the second correction coefficient. It is a map. In each of the correction coefficient maps 46a and 46b, for example, the correction coefficient is set to be smaller as the actual rotational speed and the actual fuel injection amount are increased.
  • the two correction coefficient maps 46a and 46b are set based on data obtained from experiments or the like, and are different for each model of the engine E as in the other maps. Further, each of the correspondence relationship between the actual rotational speed and the first correction coefficient and the correspondence relationship between the actual fuel injection amount and the second correction coefficient is not necessarily the correspondence relationship as shown in FIG. Further, the correction coefficient calculator 46 multiplies the calculated first and second correction coefficients by the correction coefficient multiplier 46c to calculate a torque correction coefficient. The calculated torque correction coefficient is used together with the torque change coefficient in order to calculate the torque change rate by the torque change rate calculating unit 45.
  • the torque change rate calculator 45 calculates the torque change rate based on the torque change coefficient calculated by the torque change coefficient calculator 44 and the correction coefficient calculated by the correction coefficient calculator 46.
  • the torque change rate is a value indicating the ratio of torque that changes (increases or decreases) with respect to the actual torque as described above.
  • the torque change rate calculating unit 45 calculates the torque change rate by multiplying the calculated torque change coefficient and the correction coefficient. The calculated torque change coefficient is used together with the actual torque in order to calculate the torque change amount by the torque change amount calculation unit 47.
  • the torque change amount calculation unit 47 is based on the torque change rate calculated by the torque change rate calculation unit 45 and the actual torque calculated by the actual torque calculation unit 33, and the torque of the engine E caused by the change in the actual fuel injection amount.
  • the amount of change is calculated.
  • the amount of change in torque is the amount of change in torque that changes according to the combustion state of the engine E when the actual fuel injection amount calculated by the injection amount restriction unit 32 is injected into the engine E (that is, the amount of decrease or increase in torque). ).
  • the torque change amount calculation unit 47 multiplies the torque change rate and the actual torque calculation unit 33 to calculate the torque change amount.
  • the torque change estimation unit 35 estimates the torque change amount in this way.
  • the estimated torque change amount is used for calculating the second assist torque by the second assist torque calculator 36.
  • the second assist torque calculation unit 36 (change torque calculation unit) is a second torque corresponding to the shortage of torque to compensate for the shortage of torque that has decreased with the change in the actual fuel injection amount with the output torque of the electric motor 20. Assist torque (change torque) is calculated. The calculation method will be described in detail.
  • the second assist torque calculator 36 first determines whether or not the differential value of the actual fuel injection amount calculated by the pseudo-differential calculator 42 is less than 0 (zero). If it is determined that the differential value of the actual fuel injection amount is less than zero, the second assist torque calculator 36 selects zero as the multiplication coefficient.
  • predetermined value 1
  • the drive control unit 37 calculates an assist torque to be output from the electric motor 20 based on the first assist torque and the second assist torque. That is, the drive control unit 37 calculates the assist torque by adding the first assist torque and the second assist torque. Further, the drive control unit 37 controls the inverter 22 so that the electric motor 20 outputs an assist torque.
  • the control device 30 configured in this way causes the electric motor when the load on the hydraulic pump 17 increases and the rotational speed of the engine E decreases, and when the target fuel injection amount of the engine E increases to compensate for the decreased rotational speed. 20 is driven to assist the engine E.
  • the operation of the hydraulic pump drive system 1 when the load on the hydraulic pump 17 is increased by operating any of the hydraulic actuators 11 to 15 will be described with reference to the graph of FIG.
  • the pump load load of the hydraulic pump 17
  • engine speed actual speed
  • target fuel injection amount actual fuel injection amount
  • actual fuel injection amount actual fuel injection amount
  • first assist torque differential torque
  • change torque the change over time of the assist torque
  • the horizontal axis represents time
  • the vertical axis represents various values.
  • the hydraulic pump 17 When the operation tool is operated and the control valve 18 is activated, the hydraulic pump 17 is switched from the unload state to the on-load state, and a large load acts on the hydraulic pump 17 (see time t1 in the pump load graph of FIG. 4). ).
  • the load on the hydraulic pump 17 increases, the actual rotational speed of the engine E becomes lower than the target rotational speed, and a difference occurs between the actual rotational speed of the engine E and the target rotational speed.
  • the target fuel injection amount calculation unit 38 calculates the target fuel injection amount from the difference between the actual rotation speed and the target rotation speed, and the injection amount restriction unit 32 of the control device 30 sets the calculated target fuel injection amount. Based on this, the actual fuel injection amount is calculated.
  • the injection amount limiting unit 32 limits the actual fuel injection amount, and the actual fuel injection amount is proportional to the time until the target fuel injection amount. (See times t1 to t2 in the graph of actual fuel injection amount in FIG. 4).
  • the actual fuel injection amount calculated by the injection amount restriction unit 32 is used by the actual torque calculation unit 33, and the actual torque calculation unit 33 is based on the actual rotational speed and the actual fuel injection amount calculated by the control device 30.
  • the actual torque output from the engine E is calculated.
  • the target torque calculator 31 calculates the target torque based on the target fuel injection amount and the actual rotational speed.
  • the first assist torque calculator 34 calculates a shortage of torque obtained by subtracting the actual torque from the target torque, that is, the first assist torque, based on the calculated target torque and actual torque. Since the actual fuel injection amount is limited, as shown in the graph of the first assist torque in FIG.
  • the first assist torque becomes the largest when the load of the hydraulic pump 17 increases rapidly, It decreases as the actual fuel injection amount increases (see times t1 to t2 in the graph of the first assist torque in FIG. 4). When the actual fuel injection amount reaches the target fuel injection amount, the first assist torque becomes zero (see time t2 in the graph of the first assist torque in FIG. 4).
  • the control device 30 calculates in advance a first assist torque that is a torque that is insufficient by limiting the fuel injection amount. By outputting the first assist torque from the electric motor 20, the torque output from the entire hydraulic pump drive system 1 can be brought close to the target torque even if the actual fuel injection amount is limited. Thereby, it can suppress that the torque output as the hydraulic pump drive system 1 whole falls.
  • the amount of change in the output torque is estimated in advance and the torque is output to the electric motor 20, and the engine is compared with the case where the torque is adjusted according to the deviation in the rotational speed. It can suppress that the rotation speed of E falls too much.
  • the torque change estimation unit 35 of the control device 30 calculates a torque change coefficient based on the calculated actual rotational speed and the actual fuel injection amount, and further calculates a torque change amount (second assist torque). That is, in the torque change estimation unit 35, the time constant calculation unit 41 calculates a time constant from the actual rotational speed using the time constant map 41a, and the pseudo-differential calculation unit 42 uses the calculated time constant to calculate the actual fuel injection amount. The derivative value of is calculated. Next, the torque change coefficient calculation unit 44 calculates the absolute value of the differential value of the actual fuel injection amount, and the torque change coefficient calculation unit 44 further uses the torque change coefficient map 44a to calculate the absolute value of the differential value of the actual fuel injection amount.
  • the torque change coefficient is calculated from Since the calculated torque change coefficient is calculated based on the value including the element of the first-order lag calculated by the pseudo-differential calculation unit 42, the first-order lag as shown in the torque change coefficient graph of FIG. (See times t1 to t2 in the graph of the torque change coefficient in FIG. 4).
  • the calculated torque change coefficient is expressed as a positive value.
  • the torque change coefficient changes with a first-order lag response.
  • the pseudo differential calculation unit 42 calculates the rate of change of the actual fuel injection amount for each unit speed by changing the time constant for each calculation, and the torque change amount calculation unit 47 calculates the change rate and the actual torque. Based on the above, the amount of change in the output torque for each unit speed is calculated. This is because the change in the actual fuel injection amount affects the combustion state of the engine E not only at the time of combustion immediately after supply but also over several subsequent combustions. That is, the influence on the combustion state due to the change in the actual fuel injection amount is reduced by passing the number of combustions instead of the time.
  • the pseudo-differential calculation unit 42 calculates the rate of change of the actual fuel injection amount for each unit speed. In addition, by using a pseudo-differential when calculating the rate of change of the actual fuel injection amount, the rate of change of the actual fuel injection amount becomes zero from zero even after the actual fuel injection amount reaches the target fuel injection amount and becomes constant.
  • the torque change estimation unit 35 takes into account the torque change coefficient and the torque change amount after the actual fuel injection amount reaches the target fuel injection amount and becomes constant.
  • the change in the output torque is calculated not in time units but in rotation speed units, it is possible to estimate the decrease in output torque of the engine E more accurately than in the case of calculation in time units. As a result, it is possible to prevent the rotational speed from excessively decreasing due to a decrease in output torque due to deterioration in combustion, and to suppress a decrease in fuel consumption of the engine that accompanies it. Since the torque change coefficient is calculated not according to the time but according to the number of combustions in the engine E, the time interval between times t2 and t3 is based on the value of the actual rotational speed.
  • the torque change estimation unit 35 can estimate a more accurate torque change coefficient and torque change amount.
  • the correction coefficient calculation unit 46 calculates the correction coefficient in parallel with the calculation of the torque change coefficient. That is, the correction coefficient calculator 46 calculates the first correction coefficient and the second correction coefficient based on the calculated actual rotational speed and actual fuel injection amount, respectively, and further calculates the first correction coefficient and the second correction coefficient. Based on this, a correction coefficient is calculated.
  • the torque change rate calculation unit 45 calculates the torque change rate based on the calculated correction coefficient and torque change coefficient, and the torque change amount calculation unit 47 calculates the torque change amount based on the torque change rate and the actual torque. .
  • the torque change amount calculated in this way increases with time as shown in the torque change amount in FIG. 4 and peaks at time t2, and the combustion state in the engine E improves from time t2 to time t3.
  • the torque change amount of FIG. 4 represents the torque amount to reduce as positive.
  • the torque change estimation unit 35 estimates the torque change amount, and the estimated torque change amount is used by the second assist torque calculation unit 36.
  • the second assist torque calculator 36 calculates the second assist torque based on this torque change amount.
  • the second assist torque calculation unit 36 selects a first predetermined value (for example, 1) as a multiplication coefficient when the differential value of the actual fuel injection amount calculated by the pseudo-differential calculation unit 42 is zero or more. When the differential value of the fuel injection amount is less than zero, a second predetermined value (for example, 0) is selected as the multiplication coefficient.
  • the second assist torque calculator 36 calculates the second assist torque by multiplying the torque change amount by this multiplication coefficient.
  • the drive control unit 37 calculates the assist torque by adding the calculated first assist torque and second assist torque.
  • the calculated assist torque changes as shown in the assist torque graph of FIG. 4, and further compensates for the shortage of the target torque (difference torque corresponding to the shortage of the target torque minus the actual torque).
  • a torque change amount (a change torque corresponding to a shortage of torque that decreases with a change in the actual fuel injection amount) is also compensated. Therefore, it becomes the largest when the load of the hydraulic pump 17 suddenly increases, and decreases as the actual fuel injection amount increases (see the times t1 to t2 in the graph of the torque change amount in FIG. 4).
  • the change torque (second assist) from time t2 to time t3 in order to compensate for the change in output torque caused by the transition of the combustion state of the engine E. Torque) is calculated as the assist torque.
  • the control device 30 controls the inverter 22 based on the calculated assist torque so that the electric motor 20 outputs the assist torque.
  • the hydraulic pump drive system 1 preliminarily estimates the amount of change in the output torque due to the transition of the combustion state of the engine E caused by the change in the actual fuel injection amount by the torque change estimation unit 35, and the estimated change
  • the engine E can be assisted by outputting the second assist torque corresponding to the amount from the electric motor 20. That is, a decrease in the output torque of the engine E can be estimated in advance, and the decrease can be assisted by the electric motor.
  • the hydraulic pump 17 when the hydraulic pump 17 is loaded, it is possible to prevent the output torque from being reduced due to the transition of the combustion state and the rotational speed from being excessively decreased, and the hydraulic pump associated with the excessive decrease in the rotational speed can be prevented.
  • a decrease in operability due to a decrease in the discharge flow rate can be suppressed.
  • the injection amount limiting unit 32 determines that the increase rate of the target fuel injection amount is not equal to or greater than the predetermined value, and calculates the target fuel injection amount as the actual fuel injection amount (time t4 in the graph of the actual fuel injection amount in FIG. 4). To t5). Thereby, the target torque and the actual torque calculated by each of the target torque calculation unit 31 and the actual torque calculation unit 33 coincide with each other, and the first assist torque calculation unit 34 calculates the first assist torque to be zero. (See time t4 to t5 in the graph of the first assist torque in FIG. 4).
  • the torque change estimation unit 35 estimates the torque change coefficient and the torque change amount based on the calculated actual rotational speed and the actual fuel injection amount as in the case where the operation tool is operated (torque change in FIG. 4). (Refer to times t4 to t5 in the graph of coefficient and torque change amount).
  • the second assist torque calculator 36 selects zero as the multiplication coefficient.
  • the second assist torque calculator 36 calculates the second assist torque by multiplying the torque change amount by this multiplication coefficient, so the second assist torque becomes zero.
  • the multiplication coefficient in the second assist torque calculator 36 is set to zero so that assist torque is not generated when the load is released. Thereby, when the output torque is reduced by the engine, it is possible to prevent wasteful consumption of energy by the electric motor.
  • the first assist torque calculating unit 34 sets the first assist torque to zero. Therefore, regenerative power is not generated in the electric motor, and the fuel efficiency of the engine E can be improved.
  • the injection amount limiting unit 32 has a rate limit function that does not limit the decrease rate, and the second assist torque is zero when the differential value of the actual fuel injection amount is less than zero.
  • the second assist torque calculator 36 has a function of Below, operation
  • the configuration of the hydraulic pump drive system 1A is the same as that of the hydraulic pump drive system 1 except for the functions described above, and therefore, FIG. 1 to FIG. 3 are referred to. In FIG. 5, similarly to FIG.
  • the pump load load of the hydraulic pump 17
  • the engine speed actual speed
  • the target fuel injection amount the actual fuel injection amount
  • the first assist torque the torque in order from the paper surface.
  • a change coefficient, a torque change amount, and an assist torque change with time are shown.
  • the horizontal axis represents time
  • the vertical axis represents various values.
  • the change of various values when the load is applied is the same as that of the hydraulic pump drive system 1, and the change of the various values when the load is removed is different from the hydraulic pump drive system 1.
  • the actual fuel injection amount and the first assist torque in the hydraulic pump drive system 1A change as shown in FIG. That is, when the load is lost, the actual fuel injection amount decreases stepwise in proportion to the time (see times t6 to t7 of the actual fuel injection amount in FIG. 5), and the first assist torque is calculated as the regenerative force. (Refer to times t6 to t7 of the first assist torque in FIG. 5).
  • the second assist torque calculator 36 calculates the second assist torque based on the torque change amount estimated by the torque change estimator 35 to compensate for this.
  • the first assist torque and the second assist torque calculated in this way are added by the drive control unit 37.
  • the second assist torque is output in order to compensate for the torque drop due to the transition of the fuel state of the engine E when the actual fuel injection amount is reduced when the load is released. Therefore, the output torque of the engine E is unnecessarily assisted although it is desired to quickly reduce the pump load.
  • the injection amount limiting unit 32 has a rate limiting function without limiting the reduction rate, and the second assist torque calculating unit 36 takes into account the differential value of the actual fuel injection amount.
  • the second assist torque is calculated.
  • the amount of change in torque per unit revolution (for example, torque per revolution) is simulated by changing the time constant of pseudo differentiation based on the actual revolution. Has been calculated.
  • a pseudo differential calculation may be actually performed for each unit rotation speed, and the amount of torque change for each unit rotation may be actually obtained. That is, as the actual rotational speed increases, the interval for calculating the torque change amount becomes shorter, and as the actual rotational speed decreases, the interval for calculating the torque change amount becomes longer. Thereby, the amount of change in torque per unit rotation speed can be estimated.
  • the first assist torque and the second assist torque are calculated and added to obtain the assist torque, but only one of the first assist torque and the second assist torque is used as the assist torque. It is good. That is, the hydraulic pump drive systems 1 and 1A do not necessarily have the function of calculating both the first assist torque and the second assist torque, and include the target torque calculation unit 31 and the first assist torque calculation unit 34. It does not have to be.
  • the target torque calculating unit 31, the injection amount limiting unit 32, and the first assist torque calculating unit 34 are not provided, the target fuel injection amount calculating unit 38 functions as an actual fuel injection amount calculating unit.
  • the torque change estimation unit 35 is not limited to the estimation method as described above, and any method that can estimate the change in the output torque of the engine E due to the change in the actual fuel injection amount may be used.
  • the construction machine on which the hydraulic pump drive systems 1 and 1A are mounted is not limited to a hydraulic excavator, and may be another construction machine such as a crane or a dozer, as long as it is a construction machine provided with a hydraulic actuator. Good.
  • the hydraulic pump is described as an example of the hydraulic pump.
  • the hydraulic pump is not limited to the hydraulic pump and may be a pump that discharges liquid such as water.

Abstract

This hydraulic pump drive system assists an engine by controlling an electric motor using a control device, and rotating and driving the rotating shaft of a hydraulic pump. The control device calculates a target fuel injection amount using a target fuel injection amount calculation unit, and determines an actual fuel injection amount in a manner such that the rate of change over time in the actual fuel injection amount when increasing using an injection amount restriction unit is at or below a prescribed value. In addition, the control device calculates the actual torque and the target torque using an actual torque calculation unit and a target torque calculation unit, and calculates a differential torque, which is the amount by which the actual torque is insufficient relative to the target torque, by using a first assist torque calculation unit. Furthermore, the control device controls the movement of the electric motor so as to output the differential torque, by using a drive control unit.

Description

液圧ポンプの駆動システムHydraulic pump drive system
　本発明は、エンジンと電動機とによって回転軸を回転して液圧ポンプを駆動する液圧ポンプの駆動システムに関する。 The present invention relates to a drive system for a hydraulic pump that rotates a rotating shaft by an engine and an electric motor to drive the hydraulic pump.
　建設機械等は、油圧ポンプを備えており、油圧ポンプから吐出される圧油によって油圧シリンダ等の油圧アクチュエータを作動させてアームやブーム等を動かすようになっている。油圧ポンプは、回転軸を介してエンジン及び電動機と連結されており、エンジン及び電動機によって回転駆動されるようになっている。このように構成されている建設機械として、例えば特許文献１の建設機械が知られている。 Construction machines and the like are provided with a hydraulic pump, and a hydraulic actuator such as a hydraulic cylinder is operated by pressure oil discharged from the hydraulic pump to move an arm, a boom, and the like. The hydraulic pump is connected to the engine and the electric motor via a rotating shaft, and is rotated by the engine and the electric motor. As a construction machine configured in this way, for example, a construction machine disclosed in Patent Document 1 is known.
　特許文献１の建設機械では、エンジンは、エンジンの回転数が回転数指令となるように制御装置によって制御されているが、油圧アクチュエータを駆動する場合など、油圧ポンプに負荷がかかるとエンジンの回転数が低下する。エンジンの回転数が減少して前記回転数と回転数指令との偏差が増加すると、制御装置が電動機を動かしてエンジンのパワーをアシストするようになっている。これにより、エンジンの回転数が一定（具体的には、回転数指令）に保たれる。また、制御装置は、電動機が作動した後に電動機に電力を供給する蓄電装置の充電量が減少し、前記充電量と充電量指令との偏差が増加すると時間変化率を制限しながらエンジンの目標トルクを増加させるようになっている。 In the construction machine disclosed in Patent Document 1, the engine is controlled by a control device so that the engine speed becomes a rotation speed command. However, when the hydraulic pump is loaded, such as when a hydraulic actuator is driven, the engine speed is increased. The number drops. When the rotational speed of the engine decreases and the deviation between the rotational speed and the rotational speed command increases, the control device moves the electric motor to assist the engine power. Thereby, the engine speed is kept constant (specifically, the engine speed command). Further, the control device reduces the amount of charge of the power storage device that supplies electric power to the motor after the motor is operated, and increases the deviation between the charge amount and the charge amount command, while limiting the rate of time change and the target torque of the engine Is supposed to increase.
国際公開２０１３／０３１５２５号International Publication No. 2013/031525
　特許文献１の建設機械では、エンジンと電動機とが結合されているので、エンジンの負荷トルクが増加し且つエンジンの回転数が減少すると、エンジンの回転数と回転数指令との偏差が増加する。そうすると、制御装置がエンジンの回転数と回転数指令との偏差に合せて電動機を制御し、エンジンの回転数を一定に保つように電動機によってエンジンをアシストするようになっている。 In the construction machine of Patent Document 1, since the engine and the electric motor are coupled, when the engine load torque increases and the engine speed decreases, the deviation between the engine speed and the engine speed command increases. Then, the control device controls the electric motor in accordance with the deviation between the engine speed and the engine speed command, and assists the engine with the motor so as to keep the engine speed constant.
　この場合、実際に偏差が出るまで電動機によるトルク調整が行われないので（換言すると、実際に偏差が算出された後に、電動機によるトルク調整を行うので）、油圧ポンプに負荷が掛かってエンジンの回転数が急激に低下する場合には、直ぐにトルク調整が行われずにエンジンの回転数が過度に低下することがある。 In this case, the torque adjustment by the electric motor is not performed until the deviation actually occurs (in other words, the torque adjustment by the electric motor is performed after the deviation is actually calculated). When the number decreases rapidly, the torque adjustment may not be performed immediately and the engine speed may decrease excessively.
　そこで本発明は、エンジンの回転数が過度に低下しないように電動機でアシストすることができる液圧ポンプの作動システムを提供する。 Therefore, the present invention provides a hydraulic pump operating system that can be assisted by an electric motor so that the rotational speed of the engine does not decrease excessively.
　本発明の液圧ポンプの駆動システムは、液圧ポンプの回転軸を回転駆動するエンジンと、前記回転軸の回転駆動をアシスト可能な電動機と、前記回転軸の回転数を検出する回転数センサと、前記電動機を制御する制御装置とを備え、前記制御装置は、目標燃料噴射量演算部と、噴射量制限部と、実トルク演算部と、目標トルク演算部と、差分トルク演算部と、駆動制御部と、を有し、前記目標燃料噴射量演算部は、前記回転数センサで検出される前記実回転数と目標回転数とに基づいて目標燃料噴射量を演算し、前記噴射量制限部は、前記目標燃料噴射量に基づいて実燃料噴射量を演算する際に、前記目標燃料噴射量まで段階的に実燃料噴射量を増加させる機能を有し、増加させる際の実燃料噴射量の時間変化率が所定値以下となるように実燃料噴射量を決定し、前記実トルク演算部は、前記実回転数と前記噴射量制限部で決定される前記実燃料噴射量とに基づいて前記エンジンで出力される実トルクを演算し、前記目標トルク演算部は、前記実回転数と前記目標燃料噴射量とに基づいて、前記回転軸に与えるべき目標トルクを演算し、前記差分トルク演算部は、前記目標トルクに対して前記実トルクで不足する差分トルクを演算し、前記駆動制御部は、前記差分トルクを出力させるように前記電動機を制御するものである。 A hydraulic pump drive system according to the present invention includes an engine that rotationally drives a rotary shaft of a hydraulic pump, an electric motor that can assist in the rotational drive of the rotary shaft, and a rotational speed sensor that detects the rotational speed of the rotary shaft. A control device for controlling the electric motor, the control device comprising: a target fuel injection amount calculation unit; an injection amount restriction unit; an actual torque calculation unit; a target torque calculation unit; a differential torque calculation unit; A control unit, wherein the target fuel injection amount calculation unit calculates a target fuel injection amount based on the actual rotational speed and the target rotational speed detected by the rotational speed sensor, and the injection amount restriction unit Has a function of increasing the actual fuel injection amount step by step up to the target fuel injection amount when calculating the actual fuel injection amount based on the target fuel injection amount. So that the rate of change over time is less than the specified value A fuel injection amount is determined, and the actual torque calculation unit calculates an actual torque output from the engine based on the actual rotation speed and the actual fuel injection amount determined by the injection amount limiting unit; The target torque calculation unit calculates a target torque to be applied to the rotating shaft based on the actual rotational speed and the target fuel injection amount, and the differential torque calculation unit calculates the actual torque with respect to the target torque. The deficient differential torque is calculated, and the drive control unit controls the electric motor to output the differential torque.
　本発明に従えば、実燃料噴射量の時間変化率を制限することによってエンジンの出力トルクが不足するが、その不足する出力トルクを差分トルクとして事前に演算する。この差分トルクを電動機から出力させることによって、実燃料噴射量を制限しても油圧ポンプ駆動システム全体から出力されるトルクを目標トルクに近づけることができ、油圧ポンプ駆動システム全体から出力されるトルクの低下を抑えることができる。このように、油圧ポンプ駆動システムでは、時間変化率が制限されることに起因する出力トルクの変化量を事前に推定して、その不足分のトルクを電動機に出力させて対処しており、回転数の偏差に応じてトルク調整する場合に比べてエンジンの回転数が過度に低下することを抑制することができる。これにより、エンジンの回転数が過度に低下することに伴うエンジンの燃費の低下を抑えることができる。 According to the present invention, the output torque of the engine becomes insufficient by limiting the time change rate of the actual fuel injection amount, but the insufficient output torque is calculated in advance as a differential torque. By outputting this differential torque from the electric motor, the torque output from the entire hydraulic pump drive system can be brought close to the target torque even if the actual fuel injection amount is limited, and the torque output from the entire hydraulic pump drive system can be reduced. The decrease can be suppressed. In this way, in the hydraulic pump drive system, the amount of change in output torque due to the time rate of change being limited is estimated in advance, and the shortage of torque is output to the motor to deal with it. It is possible to suppress an excessive decrease in the engine speed as compared with the case where the torque is adjusted according to the number deviation. Thereby, it is possible to suppress a decrease in fuel consumption of the engine due to an excessive decrease in the engine speed.
　上記発明において、前記噴射量制限部は、前記目標燃料噴射量が減少している場合、前記目標燃料噴射量を前記実燃料噴射量としてもよい。 In the above invention, the injection amount limiting unit may set the target fuel injection amount as the actual fuel injection amount when the target fuel injection amount is decreased.
　本発明に従えば、噴射量制限部によって実燃料噴射量が演算され、目標燃料噴射量が減少している際に目標燃料噴射量を実燃料噴射量とするようになっている。これにより、実トルク演算部及び目標トルク演算部の各々で演算される実トルク及び目標トルクが同一又は略同一となり、差分トルク演算部で演算される差分トルクがゼロとなる。それ故、エンジンの出力トルクを用いて電動機に回生させることをなくすことができ、エンジンの燃費を向上させることができる。 According to the present invention, the actual fuel injection amount is calculated by the injection amount limiting unit, and when the target fuel injection amount is decreasing, the target fuel injection amount is set as the actual fuel injection amount. As a result, the actual torque and the target torque calculated by each of the actual torque calculation unit and the target torque calculation unit are the same or substantially the same, and the differential torque calculated by the differential torque calculation unit is zero. Therefore, it is possible to eliminate regeneration of the electric motor using the output torque of the engine, and it is possible to improve the fuel consumption of the engine.
　上記発明において、前記噴射量制限部は、前記目標燃料噴射量に基づいて前記実燃料噴射量を演算する際に、前記目標燃料噴射量が増加している場合、経過時間に比例して変化させる変化規則に基づいて前記実燃料噴射量を段階的に増加させてもよい。 In the above invention, when calculating the actual fuel injection amount based on the target fuel injection amount, when the target fuel injection amount is increasing, the injection amount limiting unit changes the proportion in proportion to the elapsed time. The actual fuel injection amount may be increased stepwise based on a change rule.
　上記構成に従えば、実燃料噴射量が急激に増加することを抑制することができる。これにより、エンジンの燃焼状態が悪化することを抑制することができ、エンジンの出力トルクが低下することを抑え、且つエンジンの燃費を向上させることができる。 According to the above configuration, it is possible to suppress a sudden increase in the actual fuel injection amount. Thereby, it can suppress that the combustion state of an engine deteriorates, it can suppress that an engine output torque falls, and can improve the fuel consumption of an engine.
　上記発明において、前記噴射量制限部は、前記目標燃料噴射量に基づいて前記実燃料噴射量を演算する際に、前記目標燃料噴射量が増加している場合、経過時間に対して一次遅れさせる変化規則に基づいて前記実燃料噴射量を段階的に変化させてもよい。 In the above invention, when the target fuel injection amount is increased when the actual fuel injection amount is calculated on the basis of the target fuel injection amount, the injection amount limiting unit delays a primary delay with respect to an elapsed time. The actual fuel injection amount may be changed stepwise based on a change rule.
　上記構成に従えば、実燃料噴射量が急激に増加することを抑制することができる。これにより、エンジンの燃焼状態が悪化することを抑制することができ、エンジンの出力トルクが低下することを抑え、且つエンジンの燃費を向上させることができる。 According to the above configuration, it is possible to suppress a sudden increase in the actual fuel injection amount. Thereby, it can suppress that the combustion state of an engine deteriorates, it can suppress that an engine output torque falls, and can improve the fuel consumption of an engine.
　上記発明において、前記制御装置は、トルク変化推定部と、変化トルク演算部と、を有し、前記トルク変化推定部は、前記実燃料噴射量と前記実回転数とに基づいて前記エンジンの出力トルクの変化量を推定し、前記変化トルク演算部は、前記トルク変化推定部で演算される前記出力トルクの変化量に基づいて前記回転軸の回転駆動をアシストするように変化トルクを演算し、前記駆動制御部は、前記差分トルクに前記変化トルクを加えたトルクを出力させるように前記電動機を制御してもよい。 In the above invention, the control device includes a torque change estimation unit and a change torque calculation unit, and the torque change estimation unit is configured to output the engine based on the actual fuel injection amount and the actual rotational speed. Estimating a change amount of torque, the change torque calculating unit calculates a change torque so as to assist the rotational drive of the rotary shaft based on the change amount of the output torque calculated by the torque change estimating unit; The drive control unit may control the electric motor to output a torque obtained by adding the change torque to the differential torque.
　上記構成に従えば、実燃料噴射量の変化に起因する出力トルクの変化量（低下量）を事前に推定し、推定された変化量に基づいてアシストすべき変化トルクを演算する。演算された変化トルクは、差分トルクが加えられて電動機から出力される。このようにして、エンジンの出力トルクを電動機によってアシストすることができ、出力トルクに変化があった際にその変化分を電動機によってアシストすることができる。例えば、液圧ポンプの負荷入れ時において実燃料噴射量が急激に増加して燃焼状態が悪化するような場合であっても、上記構成においては、実燃料噴射量の変化に起因する出力トルクの低下及びエンジンの回転数の過度な低下を防ぐことができる。これにより、エンジンの回転数が過度に低下することに伴う油圧ポンプ吐出流量の低下による操作性の低下を抑えることができる。 According to the above configuration, the change amount (decrease amount) of the output torque due to the change in the actual fuel injection amount is estimated in advance, and the change torque to be assisted is calculated based on the estimated change amount. The calculated change torque is output from the electric motor with differential torque added. In this way, the output torque of the engine can be assisted by the electric motor, and when the output torque changes, the change can be assisted by the electric motor. For example, even when the actual fuel injection amount suddenly increases when the hydraulic pump is loaded and the combustion state deteriorates, the above configuration causes the output torque due to the change in the actual fuel injection amount. A decrease and an excessive decrease in the engine speed can be prevented. Thereby, the fall of operativity by the fall of the hydraulic pump discharge flow accompanying the engine speed falling too much can be suppressed.
　上記発明において、前記トルク変化推定部は、前記実燃料噴射量に基づいて前記エンジンの単位回転数当たりの前記出力トルクの変化率を推定し、前記実トルク演算部で演算される前記実トルクと前記変化率とに基づいて前記出力トルクの変化量を演算してもよい。 In the above invention, the torque change estimation unit estimates a rate of change of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and the actual torque calculated by the actual torque calculation unit The amount of change in the output torque may be calculated based on the rate of change.
　エンジンでは、実燃料噴射量の変化は、供給直後の燃焼時だけでなくその後の数回の燃焼にわたって燃焼状態へ影響を与える。即ち、時間ではなく燃焼回数を経ることによって実燃料噴射量の変化による燃焼状態への影響が小さくなってき、エンジンの燃焼状態は、時間よりも燃焼回数（即ち、回転数）に応じて変化する。 In the engine, the change in the actual fuel injection amount affects the combustion state not only at the time of combustion immediately after the supply but also over several subsequent combustions. That is, the influence on the combustion state due to the change in the actual fuel injection amount is reduced by passing the number of combustions instead of the time, and the combustion state of the engine changes according to the number of combustions (that is, the number of revolutions) rather than the time. .
　上記構成に従えば、実燃料噴射量の変化に対するエンジンの単位回転数毎の出力トルクの変化率を演算し、この変化率と実トルクとに基づいて単位回転数毎の出力トルクの変化量を演算することができる。このように時間単位ではなく回転数単位で出力トルクの変化量を演算するので、時間単位で演算する場合に比べて出力トルクの低下をより正確に推定することができる。これにより、出力トルクの変化量に基づいてエンジンをアシストすることができるようになるため、エンジンの回転数が過度に低下することを防ぐことができる。 According to the above configuration, the rate of change of the output torque for each unit revolution of the engine with respect to the change of the actual fuel injection amount is calculated, and the amount of change of the output torque for each unit revolution is calculated based on this rate of change and the actual torque. It can be calculated. Thus, since the amount of change in output torque is calculated not in time units but in rotation speed units, it is possible to estimate the decrease in output torque more accurately than in the case of calculation in time units. As a result, the engine can be assisted based on the amount of change in the output torque, so that the engine speed can be prevented from excessively decreasing.
　上記発明において、前記トルク変化推定部は、時定数を変えられる一次遅れ要素を含む疑似微分演算部と、前記実回転数に応じて前記一次遅れ要素の時定数を演算する時定数演算部とを有し、前記時定数演算部によって演算された時定数を用いた疑似微分によって前記エンジンの単位回転数当たりにおける前記実燃料噴射量の変化率を前記擬似微分演算部が算出し、前記実燃料噴射量の変化率に基づいて前記エンジンの単位回転数当たりにおける前記出力トルクの変化量を前記トルク変化推定部が推定してもよい。 In the above invention, the torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed. The pseudo-differential calculation unit calculates a rate of change of the actual fuel injection amount per unit revolution of the engine by pseudo-differentiation using the time constant calculated by the time-constant calculation unit, and the real fuel injection The torque change estimation unit may estimate the amount of change in the output torque per unit revolution of the engine based on the rate of change in the amount.
　上記構成に従えば、一次遅れ要素を含む疑似微分を用い、且つその一次遅れ要素を実回転数に応じて変えることにより、単位回転数毎の出力トルクの変化率を実用的に演算することができる。 According to the above configuration, it is possible to practically calculate the rate of change of the output torque per unit rotational speed by using a pseudo-derivative including a first-order lag element and changing the first-order lag element according to the actual rotational speed. it can.
　上記発明において、前記変化トルク演算部は、前記実燃料噴射量の変化率がゼロ未満であると、前記変化トルクをゼロとしてもよい。 In the above invention, the change torque calculation unit may set the change torque to zero when the change rate of the actual fuel injection amount is less than zero.
　上記構成に従えば、実燃料噴射量を減少させて出力トルクを低下させる際に変化トルク（アシストトルク）を電動機から発生させることを防ぐことができる。これにより、意図的にエンジンの出力トルクを低下させる際に、電動機によって無駄にエネルギーが消費されることを防ぐことができる。 According to the above configuration, it is possible to prevent the change torque (assist torque) from being generated from the electric motor when the actual fuel injection amount is decreased to reduce the output torque. As a result, when the output torque of the engine is intentionally reduced, it is possible to prevent wasteful consumption of energy by the electric motor.
　本件発明の液圧ポンプの駆動システムは、液圧ポンプの回転軸を回転駆動するエンジンと、前記回転軸の回転駆動をアシスト可能な電動機と、前記回転軸の実回転数を検出する回転数センサと、前記電動機の動きを制御する制御装置とを備え、前記制御装置は、実燃料噴射量演算部と、トルク変化推定部と、アシストトルク演算部と、駆動制御部と、を有し、前記実燃料噴射量演算部は、前記実回転数と目標回転数とに基づいて実燃料噴射量を演算し、前記トルク変化推定部は、前記実燃料噴射量と前記実回転数とに基づいて前記エンジンの出力トルクの変化量を推定し、前記変化トルク演算部は、前記出力トルクの変化量に基づいて前記回転軸の回転駆動をアシストする変化トルクを演算し、前記駆動制御部は、前記変化トルクを出力させるように前記電動機を制御するものである。 The drive system for the hydraulic pump according to the present invention includes an engine that rotationally drives a rotary shaft of the hydraulic pump, an electric motor that can assist the rotational drive of the rotary shaft, and a rotational speed sensor that detects the actual rotational speed of the rotary shaft. And a control device for controlling the movement of the electric motor, wherein the control device includes an actual fuel injection amount calculation unit, a torque change estimation unit, an assist torque calculation unit, and a drive control unit, The actual fuel injection amount calculation unit calculates an actual fuel injection amount based on the actual rotational speed and the target rotational speed, and the torque change estimation unit calculates the actual fuel injection amount based on the actual fuel injection amount and the actual rotational speed. An amount of change in engine output torque is estimated, the change torque calculation unit calculates a change torque that assists the rotational drive of the rotating shaft based on the amount of change in the output torque, and the drive control unit Torque output And controls the electric motor so that.
　上記構成に従えば、実燃燃料噴射量の変化に起因するエンジンの燃焼状態の悪化等による出力トルクの変化量（低下量）を事前に推定し、推定された変化量に基づいてアシストすべき変化トルクを演算する。演算された変化トルクは電動機から出力される。これにより、エンジンの出力トルクを電動機によってアシストすることができ、出力トルクに変化があった際にその変化分を電動機によってアシストすることができる。例えば、液圧ポンプの負荷入れ時において目標燃料噴射量が急激に増加して燃焼状態が不安定となる場合であっても、上記構成においては、それに起因する出力トルクの低下及び回転数の過度な低下を防ぐことができる。これにより、回転数が過度に低下することに伴う油圧ポンプの吐出流量の低下による操作性の低下を抑えることができる。 According to the above configuration, the change amount (decrease amount) of the output torque due to deterioration of the combustion state of the engine due to the change in the actual fuel injection amount should be estimated in advance, and assisted based on the estimated change amount Calculate the change torque. The calculated change torque is output from the electric motor. Thereby, the output torque of the engine can be assisted by the electric motor, and when the output torque changes, the change can be assisted by the electric motor. For example, even when the target fuel injection amount suddenly increases when the hydraulic pump is loaded and the combustion state becomes unstable, the above configuration causes a decrease in output torque and excessive rotation speed. Can be prevented. Thereby, the fall of operativity by the fall of the discharge flow volume of the hydraulic pump accompanying rotation number falling too much can be suppressed.
　上記発明において、前記制御装置は、実トルク演算部を有し、前記実トルク演算部は、前記回転数センサで検出される実回転数と前記実燃料噴射量とに基づいて前記エンジンで出力される実トルクを演算し、前記トルク変化推定部は、前記実燃料噴射量に基づいて前記エンジンの単位回転数当たりの前記出力トルクの変化率を推定し、前記実トルクと前記変化率とに基づいて前記出力トルクの変化量を演算してもよい。 In the above invention, the control device includes an actual torque calculation unit, and the actual torque calculation unit is output from the engine based on the actual rotation speed detected by the rotation speed sensor and the actual fuel injection amount. The torque change estimating unit estimates a change rate of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and based on the actual torque and the change rate. Then, the amount of change in the output torque may be calculated.
　上記構成に従えば、前記実燃料噴射量の変化に対する単位回転数毎の出力トルクの変化率を演算し、この変化率と実トルクとに基づいて単位回転数毎の出力トルクの変化量を演算することができる。このように時間単位ではなく回転数単位で出力トルクの変化量を演算するので、時間単位で演算する場合に比べてトルク低下をより正確に推定することができる。これにより、出力トルクの変化量に基づいてエンジンをアシストすることができるようになるため、エンジンの回転数が過度に低下することを防ぐことができる。 According to the above configuration, the change rate of the output torque for each unit speed with respect to the change in the actual fuel injection amount is calculated, and the change amount of the output torque for each unit speed is calculated based on the change rate and the actual torque. can do. As described above, since the amount of change in the output torque is calculated not in time units but in rotation speed units, it is possible to estimate the torque drop more accurately than in the case of calculation in time units. As a result, the engine can be assisted based on the amount of change in the output torque, so that the engine speed can be prevented from excessively decreasing.
　上記発明において、前記トルク変化推定部は、時定数を変えられる一次遅れ要素を含む疑似微分演算部と、前記実回転数に応じて前記一次遅れ要素の時定数を演算する時定数演算部とを有し、前記時定数演算部によって演算された時定数を用いた疑似微分によって疑似微分を用いて前記エンジンの単位回転数当たりにおける前記実燃料噴射量の変化率を前記擬似微分演算部が算出し、前記実燃料噴射量の変化率に基づいて前記エンジンの単位回転数当たりにおける前記出力トルクの変化量を前記トルク変化推定部が推定してもよい。 In the above invention, the torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed. And the pseudo-differential calculation unit calculates the rate of change of the actual fuel injection amount per unit rotational speed of the engine using pseudo-differentiation by pseudo-differentiation using the time constant calculated by the time constant calculation unit. The torque change estimation unit may estimate the change amount of the output torque per unit revolution of the engine based on the change rate of the actual fuel injection amount.
　上記構成に従えば、一次遅れ要素を含む疑似微分を用い、且つその一次遅れ要素を実回転数に応じて変えることにより、単位回転数毎の出力トルクの変化率を実用的に演算することができる。 According to the above configuration, it is possible to practically calculate the rate of change of the output torque per unit rotational speed by using a pseudo-derivative including a first-order lag element and changing the first-order lag element according to the actual rotational speed. it can.
　本発明によれば、液圧ポンプに負荷が掛かってエンジンの回転数が低下した際に、エンジンの回転数が過度に低下しないように電動機でアシストすることができる。 According to the present invention, when a load is applied to the hydraulic pump and the engine speed decreases, the motor can assist the engine speed so that the engine speed does not decrease excessively.
　本発明の上記目的、他の目的、特徴、及び利点は、添付図面参照の下、以下の好適な実施態様の詳細な説明から明らかにされる。 The above object, other objects, features, and advantages of the present invention will become apparent from the following detailed description of preferred embodiments with reference to the accompanying drawings.
本件発明の実施形態に係る油圧ポンプ駆動システムを示すブロック図である。1 is a block diagram showing a hydraulic pump drive system according to an embodiment of the present invention. 図１の油圧ポンプ駆動システムに備わる制御装置が有する機能をブロックにして示した機能ブロック図である。FIG. 2 is a functional block diagram illustrating functions of a control device provided in the hydraulic pump drive system of FIG. 1 as blocks. 図２の制御装置の一部分を更に詳細に説明すべく示した機能ブロック図である。FIG. 3 is a functional block diagram illustrating a part of the control device of FIG. 2 in more detail. 図１の油圧ポンプ駆動システムを駆動したときの各種値の経時変化を示すグラフである。It is a graph which shows the time-dependent change of various values when the hydraulic pump drive system of FIG. 1 is driven. 他の実施形態の油圧ポンプ駆動システムを駆動したときの各種値の経時変化を示すグラフである。It is a graph which shows the time-dependent change of various values when the hydraulic pump drive system of other embodiment is driven.
　以下、本発明に係る実施形態の油圧ポンプ駆動システム１について図面を参照して説明する。なお、以下の説明で用いる方向の概念は、説明する上で便宜上使用するものであって、発明の構成の向き等をその方向に限定するものではない。また、以下に説明する油圧ポンプ駆動システム１は、本発明の一実施形態に過ぎない。従って、本発明は実施形態に限定されず、発明の趣旨を逸脱しない範囲で追加、削除、変更が可能である。 Hereinafter, a hydraulic pump drive system 1 according to an embodiment of the present invention will be described with reference to the drawings. In addition, the concept of the direction used in the following description is used for convenience in description, and does not limit the direction of the configuration of the invention in that direction. Moreover, the hydraulic pump drive system 1 described below is only one embodiment of the present invention. Therefore, the present invention is not limited to the embodiments, and additions, deletions, and changes can be made without departing from the spirit of the invention.
　建設機械は、バケット、ローダ、ブレード、巻上機等の種々のアタッチメントを備え、油圧シリンダや油圧モータ（電油モータ）等の油圧アクチュエータによって動かすようになっている。例えば、建設機械の１種である油圧ショベルは、バケット、アーム及びブームを備えており、これら３つの部材を動かしながら掘削等の作業を行うことができるようになっている。バケット、アーム、及びブームの各々には油圧シリンダ１１～１３が設けられており、各シリンダ１１～１３に圧油を供給することでバケット、アーム、及びブームが動くようになっている。 Construction machines are equipped with various attachments such as buckets, loaders, blades and hoisting machines, and are moved by hydraulic actuators such as hydraulic cylinders and hydraulic motors (electro-hydraulic motors). For example, a hydraulic excavator that is a kind of construction machine includes a bucket, an arm, and a boom, and can perform operations such as excavation while moving these three members. Each of the bucket, arm, and boom is provided with hydraulic cylinders 11 to 13, and the bucket, arm, and boom are moved by supplying pressure oil to each cylinder 11-13.
　また、油圧ショベルは、走行装置を有しており、更に走行装置の上には、旋回体が旋回可能に取り付けられている。旋回体には、ブームが上下方向に揺動可能に取り付けられている。旋回体には、油圧式の旋回用モータ１４が取り付けられており、旋回用モータ１４に圧油を供給することで旋回体が旋回するようになっている。また、走行装置には、油圧式の走行用モータ１５が取り付けられており、走行用モータ１５に圧油を供給することで前進又は後退するようになっている。油圧アクチュエータ１１～１５（即ち、油圧シリンダ１１～１３及び油圧モータ１４，１５）は、油圧供給装置１６に接続されており、油圧供給装置１６から圧油の供給を受けて作動するようになっている。 Further, the hydraulic excavator has a traveling device, and a revolving body is mounted on the traveling device so as to be capable of turning. A boom is attached to the revolving structure so as to be swingable in the vertical direction. A hydraulic turning motor 14 is attached to the turning body, and the turning body is turned by supplying pressure oil to the turning motor 14. In addition, a hydraulic traveling motor 15 is attached to the traveling device, and the traveling device 15 moves forward or backward by supplying pressure oil to the traveling motor 15. The hydraulic actuators 11 to 15 (that is, the hydraulic cylinders 11 to 13 and the hydraulic motors 14 and 15) are connected to the hydraulic supply device 16 and are operated by receiving the supply of pressure oil from the hydraulic supply device 16. Yes.
　油圧供給装置１６は、油圧ポンプ１７と、コントロールバルブ１８とを有している。油圧ポンプ１７は、例えば斜板ポンプであって回転軸１７ａを有しており、回転軸１７ａを回転させることで圧油を吐出するようになっている。吐出された圧油は、コントロールバルブ１８に導かれるようになっており、コントロールバルブ１８は、吐出された圧油の流れを制御するようになっている。 The hydraulic pressure supply device 16 has a hydraulic pump 17 and a control valve 18. The hydraulic pump 17 is a swash plate pump, for example, and has a rotating shaft 17a, and discharges pressure oil by rotating the rotating shaft 17a. The discharged pressure oil is guided to the control valve 18, and the control valve 18 controls the flow of the discharged pressure oil.
　また、油圧ショベルには、複数の操作具（例えば、操作レバーや操作ボタン等）が油圧アクチュエータ１１～１５の各々に対応付けて設けられており、コントロールバルブ１８は、操作具が操作されると操作具に対応する油圧アクチュエータ１１～１５に圧油を流すようになっている。このようにして圧油を流すことで、操作具の操作に応じて油圧アクチュエータ１１～１５が作動してバケット、アーム、及びブーム等が動くようになっている。また、油圧ポンプ１７の回転軸１７ａは、油圧ポンプ駆動システム１と連結されており、油圧ポンプ駆動システム１によって回転軸１７ａが回転駆動されるようになっている。 The hydraulic excavator is provided with a plurality of operating tools (for example, operating levers and operating buttons) in association with the hydraulic actuators 11 to 15, and the control valve 18 is operated when the operating tools are operated. Pressure oil is allowed to flow through the hydraulic actuators 11 to 15 corresponding to the operation tools. By flowing the pressure oil in this manner, the hydraulic actuators 11 to 15 are operated according to the operation of the operation tool, and the bucket, arm, boom, and the like are moved. The rotary shaft 17a of the hydraulic pump 17 is connected to the hydraulic pump drive system 1, and the rotary shaft 17a is driven to rotate by the hydraulic pump drive system 1.
　油圧ポンプ駆動システム１は、エンジンＥ及び電動機２０を備えるハイブリッド式の駆動システムであり、エンジンＥ及び電動機２０が共に油圧ポンプ１７の回転軸１７ａに連結されている。エンジンＥは、例えば複数の気筒を有するディーゼルエンジンであり、気筒毎に燃料噴射装置２１が対応付けて設けられている。燃料噴射装置２１は、例えば燃料ポンプと電磁制御弁とによって構成されており、入力される噴射指令に応じた量の燃料を対応する気筒の燃焼室に噴射するようになっている。エンジンＥは、燃料噴射装置２１から噴射された燃料を燃焼させて図示しないピストンを往復運動させることで回転軸１７ａを回転させ、油圧ポンプ１７から圧油を吐出させるようになっている。なお、本実施形態では、エンジンＥがディーゼルエンジンであるが、必ずしもディーゼルエンジンである必要はなくガソリンエンジンであってもよい。また、回転軸１７ａには、エンジンＥの駆動をアシストする電動機２０が設けられている。 The hydraulic pump drive system 1 is a hybrid drive system including an engine E and an electric motor 20, and both the engine E and the electric motor 20 are connected to a rotating shaft 17 a of the hydraulic pump 17. The engine E is, for example, a diesel engine having a plurality of cylinders, and a fuel injection device 21 is provided in association with each cylinder. The fuel injection device 21 includes, for example, a fuel pump and an electromagnetic control valve, and injects an amount of fuel corresponding to an input injection command into the combustion chamber of the corresponding cylinder. The engine E burns the fuel injected from the fuel injection device 21 and reciprocates a piston (not shown) to rotate the rotating shaft 17a and discharge the hydraulic oil from the hydraulic pump 17. In the present embodiment, the engine E is a diesel engine. However, the engine E is not necessarily a diesel engine and may be a gasoline engine. The rotating shaft 17a is provided with an electric motor 20 that assists in driving the engine E.
　電動機２０は、例えばＡＣモータであって、インバータ２２に接続されている。駆動装置であるインバータ２２は、図示しないバッテリと繋がっており、バッテリから供給される直流電流を交流に変換して電動機２０に供給するようになっている。また、インバータ２２は、入力されるトルク指令に応じた周波数及び電圧の交流電流を電動機２０に供給し、トルク指令（後述するアシストトルク）に応じたトルクを電動機２０から回転軸１７ａに出力させるようになっている。 The electric motor 20 is an AC motor, for example, and is connected to the inverter 22. The inverter 22 which is a driving device is connected to a battery (not shown), and converts a direct current supplied from the battery into an alternating current and supplies the alternating current to the electric motor 20. Further, the inverter 22 supplies an alternating current having a frequency and voltage according to the input torque command to the electric motor 20 so that the torque corresponding to the torque command (assist torque described later) is output from the electric motor 20 to the rotating shaft 17a. It has become.
　また、回転軸１７ａには、回転数センサ２３が取り付けられている。回転数センサ２３は、回転軸１７ａの回転数に応じた信号を出力するようになっている。回転数センサ２３は、インバータ２２及び燃料噴射装置２１の電磁制御弁と共に制御装置３０に電気的に接続されている。 Further, a rotation speed sensor 23 is attached to the rotation shaft 17a. The rotation speed sensor 23 outputs a signal corresponding to the rotation speed of the rotation shaft 17a. The rotation speed sensor 23 is electrically connected to the control device 30 together with the inverter 22 and the electromagnetic control valve of the fuel injection device 21.
　制御装置３０は、回転数センサ２３から入力される信号に基づいて回転軸１７ａの実回転数を算出し、算出された実回転数と目標回転数との差を演算する。なお、目標回転数は、入力手段（ダイヤル、ボタン、及びタッチパネル等）から入力された又は予め設定された回転数である。制御装置３０は、実回転数と目標回転数との差に基づいて燃料噴射装置２１から噴射すべき目標燃料噴射量を演算する。更に、制御装置３０は、目標燃料噴射量に基づいて後述の方法で実燃料噴射量を演算し、この実燃料噴射量を燃料噴射装置２１から噴射させるようになっている。なお、制御装置３０は、実回転数及び目標燃料噴射量を所定の間隔で演算するようになっている。また、制御装置３０は、エンジンＥからのトルクだけでは不足する場合に電動機２０を駆動してエンジンＥをアシストするようになっている。以下では、制御装置３０の機能について図２及び図３を参照しながら更に詳細に説明する。 The control device 30 calculates the actual rotational speed of the rotating shaft 17a based on the signal input from the rotational speed sensor 23, and calculates the difference between the calculated actual rotational speed and the target rotational speed. Note that the target rotational speed is a rotational speed that is input from an input means (a dial, a button, a touch panel, or the like) or is set in advance. The control device 30 calculates a target fuel injection amount to be injected from the fuel injection device 21 based on the difference between the actual rotational speed and the target rotational speed. Further, the control device 30 calculates an actual fuel injection amount by a method to be described later based on the target fuel injection amount, and causes the fuel injection device 21 to inject this actual fuel injection amount. The control device 30 calculates the actual rotation speed and the target fuel injection amount at predetermined intervals. Further, the control device 30 assists the engine E by driving the electric motor 20 when only the torque from the engine E is insufficient. Hereinafter, the function of the control device 30 will be described in more detail with reference to FIGS. 2 and 3.
　制御装置３０は、各種値（後述する第１アシストトルク及び第２アシストトルク）を演算する機能部分を有しており、各種値を演算する機能部分毎にブロックに分けて説明すると、目標燃料噴射量演算部３８、目標トルク演算部３１、噴射量制限部３２、実トルク演算部３３、及び第１アシストトルク演算部３４を有している。目標燃料噴射量演算部３８は、実回転数と目標回転数との差に基づいて燃料噴射装置２１から噴射すべき目標燃料噴射量を演算するようになっている。目標トルク演算部３１は、目標トルクマップを用いて目標トルクを演算するようになっている。目標トルクマップは、油圧ポンプ駆動システム１全体で出力すべき目標トルクが目標燃料噴射量及び実回転数に対応付けられているマップである。目標トルク演算部３１は、演算された目標燃料噴射量及び実回転数に基づいて目標トルクマップから目標トルクを算出するようになっている。また、目標燃料噴射量演算部３８で演算される目標燃料噴射量は、燃料噴射装置２１にて実際に噴射させるべき実燃料噴射量を噴射量制限部３２で演算するために用いられる。 The control device 30 has a functional part that calculates various values (a first assist torque and a second assist torque described later). If the functional part that calculates various values is divided into blocks, the target fuel injection will be described. An amount calculation unit 38, a target torque calculation unit 31, an injection amount restriction unit 32, an actual torque calculation unit 33, and a first assist torque calculation unit 34 are provided. The target fuel injection amount calculation unit 38 calculates a target fuel injection amount to be injected from the fuel injection device 21 based on the difference between the actual rotational speed and the target rotational speed. The target torque calculator 31 calculates the target torque using the target torque map. The target torque map is a map in which the target torque to be output by the entire hydraulic pump drive system 1 is associated with the target fuel injection amount and the actual rotational speed. The target torque calculation unit 31 calculates the target torque from the target torque map based on the calculated target fuel injection amount and actual rotation speed. The target fuel injection amount calculated by the target fuel injection amount calculation unit 38 is used for the injection amount restriction unit 32 to calculate the actual fuel injection amount to be actually injected by the fuel injection device 21.
　噴射量制限部３２（実燃料噴射量演算部）は、増加率制限あり且つ減少率制限なしのレートリミット機能を有しており、このレートリミット機能により目標燃料噴射量に基づいて実燃料噴射量を演算するようになっている。更に詳細に説明すると、噴射量制限部３２は、目標燃料噴射量が増加する際に目標燃料噴射量の増加率が所定値を超えると、予め定められる変化規則に基づいて変化率又は変化量を制限しながら実燃料噴射量を前記目標燃料噴射量まで段階的に変化させるようになっている。他方、目標燃料噴射量が減少する場合、噴射量制限部３２は、減少率を制限せずに目標燃料噴射量を実燃料噴射量とするようになっている。 The injection amount limiting unit 32 (actual fuel injection amount calculation unit) has a rate limit function with an increase rate limitation and without a decrease rate limitation, and the actual fuel injection amount based on the target fuel injection amount by this rate limit function. Is calculated. More specifically, when the target fuel injection amount increases and the increase rate of the target fuel injection amount exceeds a predetermined value, the injection amount limiting unit 32 sets the change rate or the change amount based on a predetermined change rule. The actual fuel injection amount is changed stepwise up to the target fuel injection amount while limiting. On the other hand, when the target fuel injection amount decreases, the injection amount limiting unit 32 sets the target fuel injection amount as the actual fuel injection amount without limiting the reduction rate.
　本実施形態において、噴射量制限部３２は、目標燃料噴射量演算部３８で演算された目標燃料噴射量を内部に保持（即ち、記憶）し、保持している目標燃料噴射量と直後に演算された目標燃料噴射量とを比較するようになっている。保持している目標燃料噴射量より直後の目標燃料噴射量が小さい、即ち目標燃料噴射量が減少している場合、目標燃料噴射量を実燃料噴射量として算出する。他方、保持している目標燃料噴射量より直後の目標燃料噴射量が大きい、即ち目標燃料噴射量が増加している場合、増加率（本実施形態では、２つの目標燃料噴射量の差）が所定値を超えているか否かを判定する。所定値以下の場合は、標燃料噴射量を実燃料噴射量として算出する。他方、所定値を超えている場合、増加率を所定値又はそれ以下とする変化規則に基づいて増加率を制限しながら実燃料噴射量を目標燃料噴射量まで段階的に増加させる。即ち、所定値を超えている場合、所定値又はそれ以下の比例定数に基づいて時間に比例させて実燃料噴射量を目標燃料噴射量まで段階的に増加させる。なお、噴射量制限部３２は、フィルターであってもよく、例えば一次遅れ要素（即ち、遅れ要素）を有する伝達関数に基づいて目標燃料噴射量を増加させるようにしてもよい。このように演算された実燃料噴射量は、実トルクを実トルク演算部３３で演算するために実回転数と共に用いられる。 In the present embodiment, the injection amount restriction unit 32 internally holds (that is, stores) the target fuel injection amount calculated by the target fuel injection amount calculation unit 38, and calculates immediately after the held target fuel injection amount. The target fuel injection amount thus made is compared. When the target fuel injection amount immediately after the held target fuel injection amount is small, that is, when the target fuel injection amount is decreasing, the target fuel injection amount is calculated as the actual fuel injection amount. On the other hand, when the target fuel injection amount immediately after the held target fuel injection amount is large, that is, when the target fuel injection amount is increasing, the rate of increase (the difference between the two target fuel injection amounts in this embodiment) is It is determined whether or not a predetermined value is exceeded. If it is less than the predetermined value, the target fuel injection amount is calculated as the actual fuel injection amount. On the other hand, when it exceeds the predetermined value, the actual fuel injection amount is gradually increased to the target fuel injection amount while limiting the increase rate based on a change rule that sets the increase rate to a predetermined value or less. That is, when it exceeds the predetermined value, the actual fuel injection amount is increased stepwise to the target fuel injection amount in proportion to the time based on a proportional constant equal to or less than the predetermined value. The injection amount limiting unit 32 may be a filter, and may increase the target fuel injection amount based on, for example, a transfer function having a first-order lag element (that is, a lag element). The actual fuel injection amount calculated in this way is used together with the actual rotational speed in order to calculate the actual torque by the actual torque calculation unit 33.
　実トルク演算部３３は、実トルクマップを用いて実トルクを演算するようになっている。実トルクは、燃料噴射装置２１によってエンジンＥに実燃料噴射量を噴射した場合にエンジンＥが出力する出力トルクである。実トルクマップは、実トルクが実燃料噴射量及び実回転数に対応付けられているマップである。実トルク演算部３３は演算された実燃料噴射量及び実回転数に基づいて実トルクマップから実トルクを算出するようになっている。本実施形態では、実トルクマップと目標トルクマップとして同じマップが使用されている。算出された実トルクは、電動機２０で出力させたい第１アシストトルクを第１アシストトルク演算部３４で演算するために目標トルクと共に用いられる。 The actual torque calculator 33 calculates the actual torque using the actual torque map. The actual torque is an output torque output from the engine E when the fuel injection device 21 injects the actual fuel injection amount into the engine E. The actual torque map is a map in which the actual torque is associated with the actual fuel injection amount and the actual rotational speed. The actual torque calculation unit 33 calculates actual torque from the actual torque map based on the calculated actual fuel injection amount and actual rotation speed. In the present embodiment, the same map is used as the actual torque map and the target torque map. The calculated actual torque is used together with the target torque so that the first assist torque calculator 34 calculates the first assist torque to be output by the electric motor 20.
　第１アシストトルク演算部３４（差分トルク演算部）は、１つの目標燃料噴射量から演算される実トルクと目標トルクとに基づいて、目標トルクから実トルクを差し引いた不足分のトルクである第１アシストトルク（差分トルク）を演算するようになっている。更に詳細に説明すると、第１アシストトルク演算部３４は、目標トルクから実トルクを減算し、油圧ポンプ駆動システム１から目標トルクを発生させる上で不足する第１アシストトルクを演算する。 The first assist torque calculation unit 34 (difference torque calculation unit) is a shortage torque obtained by subtracting the actual torque from the target torque based on the actual torque calculated from one target fuel injection amount and the target torque. One assist torque (difference torque) is calculated. More specifically, the first assist torque calculator 34 subtracts the actual torque from the target torque, and calculates the first assist torque that is insufficient to generate the target torque from the hydraulic pump drive system 1.
　このように、制御装置３０では、目標燃料噴射量が急激に増加したときに実燃料噴射量の増加率を制限するようになっている。このように増加率を制限することによって、目標燃料噴射量の急激な増加に起因するエンジンＥの燃焼状態の悪化を防ぐことができ、燃費向上を図ることができる。他方、制限されることで実際に出力される実トルクが目標トルクより小さくなる、即ち不足するトルクが生じるので、不足分を電動機２０に出力させるべく、不足分に相当する第１アシストトルクを演算している。 As described above, the control device 30 is configured to limit the rate of increase of the actual fuel injection amount when the target fuel injection amount suddenly increases. By limiting the increase rate in this way, it is possible to prevent deterioration of the combustion state of the engine E due to a rapid increase in the target fuel injection amount, and to improve fuel efficiency. On the other hand, since the actual torque actually output becomes smaller than the target torque by being limited, that is, insufficient torque is generated, the first assist torque corresponding to the shortage is calculated in order to cause the motor 20 to output the shortage. is doing.
　また、油圧ポンプ駆動システム１では、実燃料噴射量の増加率が制限されることによって、エンジンＥの出力トルクが低下する。しかし、制御装置３０は、低下した出力トルクを推定し、更に低下した出力トルクを電動機２０で補うべく第２アシストトルク（変化トルク）を演算する機能を有している。制御装置３０は、第２アシストトルクを演算するために、トルク変化推定部３５と、第２アシストトルク演算部３６と、駆動制御部３７とを有している。 Further, in the hydraulic pump drive system 1, the output torque of the engine E is reduced by limiting the increase rate of the actual fuel injection amount. However, the control device 30 has a function of estimating the reduced output torque and calculating the second assist torque (change torque) so as to supplement the reduced output torque with the electric motor 20. The control device 30 includes a torque change estimation unit 35, a second assist torque calculation unit 36, and a drive control unit 37 in order to calculate the second assist torque.
　トルク変化推定部３５は、演算された実回転数及び実燃料噴射量に基づいて、エンジンＥから出力されるトルクの変化量を推定するようになっている。エンジンＥは、実燃料噴射量の変化により燃焼状態が不安定となり、出力トルクに応答遅れが生じる。また、エンジンＥの燃焼状態は、一回転数毎（４ストロークエンジンの場合、吸気－圧縮－膨張－排気の一サイクル毎）に変化し、燃焼状態の不安定状態は、燃焼回数を経るにつれて改善される。従って、実回転数が大きければ大きい程、単位時間当たりの燃焼回数が多くなるので、エンジンＥの燃焼状態の不安定化がより早く改善し、エンジンＥのトルクの低下が小さくなる。 The torque change estimator 35 estimates the amount of change in torque output from the engine E based on the calculated actual rotational speed and actual fuel injection amount. In the engine E, the combustion state becomes unstable due to a change in the actual fuel injection amount, and a response delay occurs in the output torque. In addition, the combustion state of the engine E changes every revolution (in the case of a 4-stroke engine, every cycle of intake-compression-expansion-exhaust), and the unstable state of the combustion state improves as the number of combustions increases. Is done. Accordingly, as the actual rotational speed is larger, the number of combustions per unit time is increased, so that the instability of the combustion state of the engine E is improved more quickly, and the decrease in the torque of the engine E is reduced.
　燃焼状態が一回転毎に変化するというエンジンＥの出力トルクの特性を鑑みて、トルク変化推定部３５は、エンジンＥの単位回転数毎（好ましくは、一回転毎）に出力トルクの低下を演算するようになっている。本実施形態において、トルク変化推定部３５では、後述する疑似微分を含む伝達関数によってエンジンＥを数値モデル化してエンジンＥの出力トルクの変化を推定するようにし、更に疑似微分に含まれる一次遅れ要素の時定数を実回転数に応じて変化させている。これにより、単位回転数毎の出力トルク低下を疑似的に演算することができる。そうすると、実回転数が大きい程エンジンＥの燃焼状態がより早く改善してトルク低下が抑えられ、且つ実回転数が小さい程エンジンＥの燃焼状態の改善が遅くなってトルク低下が大きくなることが考慮される。即ち、実回転数に応じてトルクの応答遅れが変化するエンジンＥの出力トルク特性が、前述する伝達関数によって推定できる。このように出力トルクの変化量を推定するトルク変化推定部３５について、図２に併せて図３も参照しながら以下に更に詳細に説明する。 In view of the characteristics of the output torque of the engine E that the combustion state changes every rotation, the torque change estimation unit 35 calculates a decrease in the output torque at every unit rotation speed (preferably every rotation) of the engine E. It is supposed to be. In the present embodiment, the torque change estimating unit 35 numerically models the engine E using a transfer function including a pseudo-derivative described later to estimate the change in the output torque of the engine E, and further includes a first-order lag element included in the pseudo-differential. The time constant is changed according to the actual rotational speed. Thereby, it is possible to artificially calculate the output torque drop for each unit rotation speed. As a result, the higher the actual rotational speed, the faster the combustion state of the engine E improves and the torque reduction is suppressed, and the smaller the actual rotational speed, the slower the improvement of the combustion state of the engine E and the greater the torque reduction. Be considered. That is, the output torque characteristic of the engine E in which the response delay of the torque changes according to the actual rotational speed can be estimated by the above-described transfer function. The torque change estimator 35 that estimates the amount of change in the output torque will be described in more detail below with reference to FIG. 3 in addition to FIG.
　トルク変化推定部３５は、出力トルクの変化を推定する機能部分として、時定数演算部４１と、疑似微分演算部４２と、トルク変化係数演算部４４と、トルク変化率演算部４５と、補正係数演算部４６と、トルク変化量演算部４７とを有している。時定数演算部４１は、時定数マップを用いて制御装置３０で演算された実回転数から時定数を算出する。本実施形態において、時定数マップは、時定数と実回転とが対応付けられているマップである。時定数マップの時定数と実回転との対応関係は、実験等から得られたデータに基づいて設定されており、エンジンＥの排気量、付属品（過給機やＥＧＲ等）、及び構造（配管の径や長さ等）等によって異なる。即ち、前記対応関係は、エンジンＥの機種毎に異なっており、エンジンＥの機種毎に実験結果を参考にして設定される。なお、前記対応関係は、機種毎だけでなく個体毎に設定されてもよい。時定数演算部４１で演算される時定数は、実燃料噴射量の微分値を演算するために疑似微分演算部４２で実燃料噴射量と共に用いられる。 The torque change estimator 35 includes a time constant calculator 41, a pseudo-differential calculator 42, a torque change coefficient calculator 44, a torque change rate calculator 45, and a correction coefficient as functional parts for estimating a change in output torque. A calculation unit 46 and a torque change amount calculation unit 47 are provided. The time constant calculation unit 41 calculates a time constant from the actual rotational speed calculated by the control device 30 using the time constant map. In the present embodiment, the time constant map is a map in which the time constant is associated with the actual rotation. The correspondence between the time constant of the time constant map and the actual rotation is set based on data obtained from experiments and the like. The displacement of the engine E, accessories (supercharger, EGR, etc.), and structure ( It depends on the pipe diameter and length. That is, the correspondence is different for each model of the engine E, and is set for each model of the engine E with reference to the experimental result. The correspondence relationship may be set not only for each model but also for each individual. The time constant calculated by the time constant calculating unit 41 is used together with the actual fuel injection amount by the pseudo-differential calculating unit 42 in order to calculate a differential value of the actual fuel injection amount.
　疑似微分演算部４２は、エンジンＥを数値モデル化した伝達関数によって実燃料噴射量の微分値を演算する。なお、エンジンＥでは、燃料噴射量とトルクとが対応しており、実燃料噴射量の微分値（実燃料噴射量の単位回転数当たりの変化率に相当）は、トルクの変化率に対応している。疑似微分演算部４２について更に詳細に説明すると、疑似微分演算部４２の伝達関数には、一次遅れ要素を含む疑似微分（不完全微分ともいう）が含まれており、疑似微分演算部４２は、この伝達関数を用いて実燃料噴射量の微分値を演算するようになっている。本実施形態において、疑似微分は、ラプラス変数をｓとし、微分ゲインをＴＤとし、時定数をＴとすると、下記の式（１）で表される。 The pseudo-differential calculation unit 42 calculates a differential value of the actual fuel injection amount by a transfer function obtained by numerically modeling the engine E. In the engine E, the fuel injection amount corresponds to the torque, and the differential value of the actual fuel injection amount (corresponding to the rate of change of the actual fuel injection amount per unit revolution) corresponds to the rate of change of the torque. ing. The pseudo differential operation unit 42 will be described in more detail. The transfer function of the pseudo differential operation unit 42 includes a pseudo differential (also referred to as incomplete differentiation) including a first-order lag element. A differential value of the actual fuel injection amount is calculated using this transfer function. In the present embodiment, the pseudo-differentiation, the Laplace variable and s, the differential gain and T D, when the constant is T time, represented by the following formula (1).
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
　このように一次遅れ要素を含む疑似微分によって実燃料噴射量の微分値を演算することで、燃焼状態の悪化による応答遅れが考慮された出力トルクの変化率に対応する値（即ち、実燃料噴射量の微分値）が演算される。また、疑似微分に含まれる一次遅れ要素の時定数Ｔは、時定数演算部４１で演算された時定数を用いる。即ち、疑似微分演算部４２は、演算する度に時定数を変化させて実燃料噴射量の微分値を演算する。このように時定数を実回転数に基づいて演算して、時定数を演算する度に変更することで、単位回転数毎（好ましくは、一回転数毎）の出力トルクの変化率を疑似的に演算することができる。このようにして演算される実燃料噴射量の微分値は、エンジンＥの出力トルクの単位回転数当たりの変化率に対応しており、後述するトルク変化係数をトルク変化係数演算部４４で演算するために用いられる。 Thus, by calculating the differential value of the actual fuel injection amount by the pseudo differential including the first-order lag element, a value corresponding to the rate of change of the output torque considering the response delay due to the deterioration of the combustion state (that is, the actual fuel injection) The differential value of the quantity is calculated. Further, the time constant calculated by the time constant calculation unit 41 is used as the time constant T of the first-order lag element included in the pseudo differentiation. That is, the pseudo-differential calculation unit 42 calculates the differential value of the actual fuel injection amount by changing the time constant every time it is calculated. Thus, by calculating the time constant based on the actual rotation speed and changing it every time the time constant is calculated, the rate of change of the output torque for each unit rotation speed (preferably for each rotation speed) is simulated. Can be calculated. The differential value of the actual fuel injection amount calculated in this way corresponds to the rate of change per unit rotational speed of the output torque of the engine E, and the torque change coefficient described later is calculated by the torque change coefficient calculating unit 44. Used for.
　トルク変化係数演算部４４は、疑似微分演算部４２で演算された実燃料噴射量の微分値に基づいてトルク変化係数を演算するようになっている。トルク変化係数は、実トルクに対してどの程度トルクが変化するかを示す係数である。トルク変化係数演算部４４は、まず実燃料噴射量の微分値の絶対値を演算し、次に図３に示すトルク変化係数マップ４４ａを用いて実燃料噴射量の微分値の絶対値からトルク変化係数を算出する。トルク変化係数マップ４４ａは、実燃料噴射量の微分値の絶対値とトルク変化係数とが対応付けられているマップであり、例えば微分値の絶対値が大きくなるとトルク変化係数が大きくなるように設定されている。本実施形態において、トルク変化係数マップ４４ａの実燃料噴射量の微分値の絶対値とトルク変化係数との対応関係は、実験等から得られたデータに基づいて設定されており、時定数マップと同様にエンジンＥの機種毎に設定されている。なお、実燃料噴射量の微分値の絶対値とトルク変化係数との対応関係は、必ずしも図３に示されるような対応関係である必要はない。トルク変化係数演算部４４は、トルク変化係数マップ４４ａと実燃料噴射量の微分値の絶対値とに基づいてトルク変化係数を演算し、演算されたトルク変化係数は、トルク変化率をトルク変化率演算部４５で演算するために用いられる。 The torque change coefficient calculation unit 44 calculates a torque change coefficient based on the differential value of the actual fuel injection amount calculated by the pseudo-differential calculation unit 42. The torque change coefficient is a coefficient indicating how much the torque changes with respect to the actual torque. The torque change coefficient calculating unit 44 first calculates the absolute value of the differential value of the actual fuel injection amount, and then uses the torque change coefficient map 44a shown in FIG. 3 to change the torque change from the absolute value of the differential value of the actual fuel injection amount. Calculate the coefficient. The torque change coefficient map 44a is a map in which the absolute value of the differential value of the actual fuel injection amount is associated with the torque change coefficient. For example, the torque change coefficient map 44a is set so that the torque change coefficient increases as the absolute value of the differential value increases. Has been. In the present embodiment, the correspondence between the absolute value of the differential value of the actual fuel injection amount of the torque change coefficient map 44a and the torque change coefficient is set based on data obtained from experiments or the like, and the time constant map and Similarly, it is set for each model of the engine E. The correspondence relationship between the absolute value of the differential value of the actual fuel injection amount and the torque change coefficient is not necessarily the correspondence relationship as shown in FIG. The torque change coefficient calculation unit 44 calculates a torque change coefficient based on the torque change coefficient map 44a and the absolute value of the differential value of the actual fuel injection amount, and the calculated torque change coefficient indicates the torque change rate as the torque change rate. It is used for calculation by the calculation unit 45.
　トルク変化率は、実燃料噴射量の燃料をエンジンＥに噴いたときに出力される実トルクに対して、燃焼状態の悪化等に伴って変化（具体的には、減少）するトルクの割合を示す値である。トルク変化係数とトルク変化率とは、基本的に対応しているが、トルク変化係数は、実燃料噴射量の微分値の絶対値から一義的に導かれるように設定された値である。これに対して、トルク変化率は、実燃料噴射量の微分値の絶対値（即ち、トルク変化係数）だけでなく、実回転数及び実燃料噴射量の影響が加味されている。例えば、エンジンＥに排気ターボ機能が備わっている場合、低回転域では、そのターボによって吸気遅れが増大して、出力トルクの低下が増大する。このような現象を加味すべく、トルク変化率は、トルク変化係数演算部４４で演算されるトルク変化係数を補正するようになっており、補正するための補正係数を補正係数演算部４６で演算している。 The rate of change in torque is the ratio of torque that changes (specifically decreases) as the combustion state deteriorates, etc., relative to the actual torque that is output when fuel of the actual fuel injection amount is injected into the engine E. This is the value shown. The torque change coefficient and the torque change rate basically correspond to each other, but the torque change coefficient is a value set so as to be uniquely derived from the absolute value of the differential value of the actual fuel injection amount. On the other hand, the torque change rate takes into account not only the absolute value of the differential value of the actual fuel injection amount (that is, the torque change coefficient) but also the effects of the actual rotational speed and the actual fuel injection amount. For example, when the engine E has an exhaust turbo function, in the low speed range, the intake air delay increases due to the turbo, and the output torque decreases. In consideration of such a phenomenon, the torque change rate is corrected by the torque change coefficient calculated by the torque change coefficient calculating unit 44, and the correction coefficient for correction is calculated by the correction coefficient calculating unit 46. is doing.
　補正係数演算部４６は、制御装置３０で演算される実回転数及び噴射量制限部３２で演算される実燃料噴射量に基づいて補正係数を演算するようになっている。補正係数は、トルク変化係数演算部４４で演算されたトルク変化係数を実回転数及び実燃料噴射量に応じて補正するための係数である。更に詳細に説明すると、補正係数演算部４６は、図３に示すような第１補正係数マップ４６ａを用いて実回転数から第１補正係数を演算し、図３に示すような第２補正係数マップ４６ｂを用いて実燃料噴射量から第２補正係数を演算する。第１補正係数マップ４６ａは、実回転数と第１補正係数とが対応付けられているマップであり、第２補正係数マップ４６ｂは、実燃料噴射量と第２補正係数とが対応付けられているマップである。各補正係数マップ４６ａ，４６ｂでは、例えば実回転数及び実燃料噴射量が大きくなると補正係数が小さくなるように設定されている。 The correction coefficient calculation unit 46 calculates a correction coefficient based on the actual rotational speed calculated by the control device 30 and the actual fuel injection amount calculated by the injection amount limiting unit 32. The correction coefficient is a coefficient for correcting the torque change coefficient calculated by the torque change coefficient calculating unit 44 according to the actual rotational speed and the actual fuel injection amount. More specifically, the correction coefficient calculator 46 calculates the first correction coefficient from the actual rotational speed using the first correction coefficient map 46a as shown in FIG. 3, and the second correction coefficient as shown in FIG. A second correction coefficient is calculated from the actual fuel injection amount using the map 46b. The first correction coefficient map 46a is a map in which the actual rotational speed and the first correction coefficient are associated with each other, and the second correction coefficient map 46b is in association with the actual fuel injection amount and the second correction coefficient. It is a map. In each of the correction coefficient maps 46a and 46b, for example, the correction coefficient is set to be smaller as the actual rotational speed and the actual fuel injection amount are increased.
　なお、２つの補正係数マップ４６ａ，４６ｂは、実験等から得られたデータに基づいて設定されており、他のマップと同様にエンジンＥの機種毎に異なっている。また、実回転数と第１補正係数との対応関係及び実燃料噴射量と第２補正係数との対応関係の各々は、必ずしも図３に示されるような対応関係である必要はない。更に、補正係数演算部４６は、演算された第１及び第２補正係数を補正係数乗算部４６ｃによって乗算してトルク補正係数を算出する。算出されたトルク補正係数は、トルク変化率をトルク変化率演算部４５で演算するためにトルク変化係数と共に用いられる。 The two correction coefficient maps 46a and 46b are set based on data obtained from experiments or the like, and are different for each model of the engine E as in the other maps. Further, each of the correspondence relationship between the actual rotational speed and the first correction coefficient and the correspondence relationship between the actual fuel injection amount and the second correction coefficient is not necessarily the correspondence relationship as shown in FIG. Further, the correction coefficient calculator 46 multiplies the calculated first and second correction coefficients by the correction coefficient multiplier 46c to calculate a torque correction coefficient. The calculated torque correction coefficient is used together with the torque change coefficient in order to calculate the torque change rate by the torque change rate calculating unit 45.
　トルク変化率演算部４５は、トルク変化係数演算部４４で演算されるトルク変化係数と補正係数演算部４６で演算される補正係数とに基づいてトルク変化率を演算するようになっている。トルク変化率は、前述の通り実トルクに対して変化（増加又は減少）するトルクの割合を示す値である。トルク変化率演算部４５は、演算されるトルク変化係数及び補正係数を乗算することによりトルク変化率を算出している。算出されたトルク変化係数は、トルク変化量をトルク変化量演算部４７で演算するために実トルクと共に用いられる。 The torque change rate calculator 45 calculates the torque change rate based on the torque change coefficient calculated by the torque change coefficient calculator 44 and the correction coefficient calculated by the correction coefficient calculator 46. The torque change rate is a value indicating the ratio of torque that changes (increases or decreases) with respect to the actual torque as described above. The torque change rate calculating unit 45 calculates the torque change rate by multiplying the calculated torque change coefficient and the correction coefficient. The calculated torque change coefficient is used together with the actual torque in order to calculate the torque change amount by the torque change amount calculation unit 47.
　トルク変化量演算部４７は、トルク変化率演算部４５で演算されるトルク変化率及び実トルク演算部３３で演算される実トルクに基づいて、実燃料噴射量の変化に起因するエンジンＥのトルク変化量を演算するようになっている。トルク変化量は、噴射量制限部３２で演算される実燃料噴射量をエンジンＥに噴射した際にエンジンＥの燃焼状態に応じて変化したトルクの変化量（即ち、トルクの低下量又は増加量）である。トルク変化量演算部４７は、トルク変化率及び実トルク演算部３３を乗算してトルク変化量を算出する。トルク変化推定部３５では、このようにしてトルク変化量が推定される。推定されたトルク変化量は、第２アシストトルクを第２アシストトルク演算部３６で演算するために用いられる。 The torque change amount calculation unit 47 is based on the torque change rate calculated by the torque change rate calculation unit 45 and the actual torque calculated by the actual torque calculation unit 33, and the torque of the engine E caused by the change in the actual fuel injection amount. The amount of change is calculated. The amount of change in torque is the amount of change in torque that changes according to the combustion state of the engine E when the actual fuel injection amount calculated by the injection amount restriction unit 32 is injected into the engine E (that is, the amount of decrease or increase in torque). ). The torque change amount calculation unit 47 multiplies the torque change rate and the actual torque calculation unit 33 to calculate the torque change amount. The torque change estimation unit 35 estimates the torque change amount in this way. The estimated torque change amount is used for calculating the second assist torque by the second assist torque calculator 36.
　第２アシストトルク演算部３６（変化トルク演算部）は、実燃料噴射量の変化に伴って低下したトルクの不足分を電動機２０の出力トルクで補うべく、その不足分のトルクに相当する第２アシストトルク（変化トルク）を演算するようになっている。演算方法について詳細に説明する。第２アシストトルク演算部３６は、まず疑似微分演算部４２で演算された実燃料噴射量の微分値が０（ゼロ）未満か否かを判定する。実燃料噴射量の微分値がゼロ未満であると判定すると、第２アシストトルク演算部３６は、乗算係数としてゼロを選択する。実燃料噴射量の微分値がゼロ以上と判定すると、第２アシストトルク演算部３６は、乗算係数として所定値（本実施形態では、所定値＝１）を選択する。更に、第２アシストトルク演算部３６は、乗算係数とトルク変化量とを乗算して乗算結果を第２アシストトルクとして算出する。従って、微分値がゼロ未満の場合、第２アシストトルクはゼロとなり、微分値がゼロ以上である場合、第２アシストトルクはトルク変化量となる。このようにして算出された第２アシストトルクは、電動機２０から出力すべきアシストトルクを駆動制御部３７で演算するために第１アシストトルクと共に用いられる。 The second assist torque calculation unit 36 (change torque calculation unit) is a second torque corresponding to the shortage of torque to compensate for the shortage of torque that has decreased with the change in the actual fuel injection amount with the output torque of the electric motor 20. Assist torque (change torque) is calculated. The calculation method will be described in detail. The second assist torque calculator 36 first determines whether or not the differential value of the actual fuel injection amount calculated by the pseudo-differential calculator 42 is less than 0 (zero). If it is determined that the differential value of the actual fuel injection amount is less than zero, the second assist torque calculator 36 selects zero as the multiplication coefficient. When it is determined that the differential value of the actual fuel injection amount is equal to or greater than zero, the second assist torque calculation unit 36 selects a predetermined value (in this embodiment, predetermined value = 1) as a multiplication coefficient. Further, the second assist torque calculator 36 multiplies the multiplication coefficient by the torque change amount and calculates the multiplication result as the second assist torque. Accordingly, when the differential value is less than zero, the second assist torque is zero, and when the differential value is greater than or equal to zero, the second assist torque is a torque change amount. The second assist torque calculated in this way is used together with the first assist torque so that the drive control unit 37 calculates the assist torque to be output from the electric motor 20.
　駆動制御部３７は、第１アシストトルク及び第２アシストトルクに基づいて電動機２０から出力すべきアシストトルクを演算する。即ち、駆動制御部３７は、第１アシストトルクと第２アシストトルクとを加算することによってアシストトルクを演算する。また、駆動制御部３７は、電動機２０にアシストトルクを出力させるべくインバータ２２を制御するようになっている。 The drive control unit 37 calculates an assist torque to be output from the electric motor 20 based on the first assist torque and the second assist torque. That is, the drive control unit 37 calculates the assist torque by adding the first assist torque and the second assist torque. Further, the drive control unit 37 controls the inverter 22 so that the electric motor 20 outputs an assist torque.
　このように構成されている制御装置３０は、油圧ポンプ１７の負荷が大きくなってエンジンＥの回転数が低下し、低下した回転数を補うべくエンジンＥの目標燃料噴射量が増加した際に電動機２０を駆動してエンジンＥをアシストするようになっている。以下では、油圧アクチュエータ１１～１５の何れかを作動させて油圧ポンプ１７の負荷が増大した際の油圧ポンプ駆動システム１の動きを図４のグラフを参照しながら説明する。なお、図４には、紙面の上から順にポンプ負荷（油圧ポンプ１７の負荷）、エンジン回転数（実回転数）、目標燃料噴射量、実燃料噴射量、第１アシストトルク（差分トルク）、トルク変化係数、第２アシストトルク（変化トルク）、及びアシストトルクの経時変化を示している。図４の横軸が時間であり、縦軸が各種値を示している。 The control device 30 configured in this way causes the electric motor when the load on the hydraulic pump 17 increases and the rotational speed of the engine E decreases, and when the target fuel injection amount of the engine E increases to compensate for the decreased rotational speed. 20 is driven to assist the engine E. Hereinafter, the operation of the hydraulic pump drive system 1 when the load on the hydraulic pump 17 is increased by operating any of the hydraulic actuators 11 to 15 will be described with reference to the graph of FIG. In FIG. 4, the pump load (load of the hydraulic pump 17), engine speed (actual speed), target fuel injection amount, actual fuel injection amount, first assist torque (differential torque), The torque change coefficient, the second assist torque (change torque), and the change over time of the assist torque are shown. In FIG. 4, the horizontal axis represents time, and the vertical axis represents various values.
　操作具が操作されてコントロールバルブ１８が作動すると、油圧ポンプ１７は、アンロード状態からオンロード状態に切替り、油圧ポンプ１７に大きな負荷が作用する（図４のポンプ負荷のグラフの時刻ｔ１参照）。油圧ポンプ１７の負荷が大きくなるとエンジンＥの実回転数が目標回転数より低くなり、エンジンＥの実回転数と目標回転数とに差が生じる。そうすると、目標燃料噴射量演算部３８は、実回転数と目標回転数との差から目標燃料噴射量を演算し、更に制御装置３０の噴射量制限部３２は、演算された目標燃料噴射量に基づいて実燃料噴射量を演算する。噴射量制限部３２は、目標燃料噴射量の増加率（又は増加量）が所定値以上であるので、実燃料噴射量を制限して、実燃料噴射量を目標燃料噴射量まで時間に比例して段階的に増加させる（図４の実燃料噴射量のグラフの時刻ｔ１～ｔ２参照）。 When the operation tool is operated and the control valve 18 is activated, the hydraulic pump 17 is switched from the unload state to the on-load state, and a large load acts on the hydraulic pump 17 (see time t1 in the pump load graph of FIG. 4). ). When the load on the hydraulic pump 17 increases, the actual rotational speed of the engine E becomes lower than the target rotational speed, and a difference occurs between the actual rotational speed of the engine E and the target rotational speed. Then, the target fuel injection amount calculation unit 38 calculates the target fuel injection amount from the difference between the actual rotation speed and the target rotation speed, and the injection amount restriction unit 32 of the control device 30 sets the calculated target fuel injection amount. Based on this, the actual fuel injection amount is calculated. Since the increase rate (or increase amount) of the target fuel injection amount is equal to or greater than a predetermined value, the injection amount limiting unit 32 limits the actual fuel injection amount, and the actual fuel injection amount is proportional to the time until the target fuel injection amount. (See times t1 to t2 in the graph of actual fuel injection amount in FIG. 4).
　噴射量制限部３２で演算された実燃料噴射量は、実トルク演算部３３で用いられ、実トルク演算部３３は、制御装置３０で演算される実回転数と実燃料噴射量とに基づいてエンジンＥで出力される実トルクを演算する。他方、目標トルク演算部３１は、目標燃料噴射量と実回転数とに基づいて目標トルクを演算する。次に、第１アシストトルク演算部３４は、演算された目標トルク及び実トルクに基づいて、目標トルクから実トルクを差し引いた不足分のトルク、即ち第１アシストトルクを演算する。実燃料噴射量が制限されているため、図４の第１アシストトルクのグラフに示されているように、第１アシストトルクは、油圧ポンプ１７の負荷が急激に増加した際に最も大きくなり、実燃料噴射量の増加と共に減少するようになっている（図４の第１アシストトルクのグラフの時刻ｔ１～ｔ２参照）。そして、実燃料噴射量が目標燃料噴射量に達すると、第１アシストトルクがゼロとなる（図４の第１アシストトルクのグラフの時刻ｔ２参照）。 The actual fuel injection amount calculated by the injection amount restriction unit 32 is used by the actual torque calculation unit 33, and the actual torque calculation unit 33 is based on the actual rotational speed and the actual fuel injection amount calculated by the control device 30. The actual torque output from the engine E is calculated. On the other hand, the target torque calculator 31 calculates the target torque based on the target fuel injection amount and the actual rotational speed. Next, the first assist torque calculator 34 calculates a shortage of torque obtained by subtracting the actual torque from the target torque, that is, the first assist torque, based on the calculated target torque and actual torque. Since the actual fuel injection amount is limited, as shown in the graph of the first assist torque in FIG. 4, the first assist torque becomes the largest when the load of the hydraulic pump 17 increases rapidly, It decreases as the actual fuel injection amount increases (see times t1 to t2 in the graph of the first assist torque in FIG. 4). When the actual fuel injection amount reaches the target fuel injection amount, the first assist torque becomes zero (see time t2 in the graph of the first assist torque in FIG. 4).
　このように、油圧ポンプ駆動システム１では、実燃料噴射量の増加率（又は増加量）を制限して実燃料噴射量が急激に変化することを抑制することができる。これにより、エンジンＥの燃焼状態が悪化することを抑制することができ、エンジンＥの燃費を向上させることができる。また、制御装置３０は、燃料噴射量を制限することによって不足するトルクである第１アシストトルクを予め演算している。この第１アシストトルクを電動機２０から出力させることによって、実燃料噴射量を制限しても油圧ポンプ駆動システム１全体から出力されるトルクを目標トルクに近づけることができる。これにより、油圧ポンプ駆動システム１全体として出力されるトルクが低下することを抑えることができる。このように、油圧ポンプ駆動システム１では、出力トルクの変化量を事前に推定して電動機２０にトルクを出力させて対処しており、回転数の偏差に応じてトルク調整する場合に比べてエンジンＥの回転数が過度に低下することを抑制することができる。 As described above, in the hydraulic pump drive system 1, it is possible to limit the increase rate (or increase amount) of the actual fuel injection amount and suppress the sudden change in the actual fuel injection amount. Thereby, it can suppress that the combustion state of the engine E deteriorates, and the fuel consumption of the engine E can be improved. In addition, the control device 30 calculates in advance a first assist torque that is a torque that is insufficient by limiting the fuel injection amount. By outputting the first assist torque from the electric motor 20, the torque output from the entire hydraulic pump drive system 1 can be brought close to the target torque even if the actual fuel injection amount is limited. Thereby, it can suppress that the torque output as the hydraulic pump drive system 1 whole falls. Thus, in the hydraulic pump drive system 1, the amount of change in the output torque is estimated in advance and the torque is output to the electric motor 20, and the engine is compared with the case where the torque is adjusted according to the deviation in the rotational speed. It can suppress that the rotation speed of E falls too much.
　また、制御装置３０のトルク変化推定部３５は、演算された実回転数及び実燃料噴射量に基づいてトルク変化係数を算出し、更にトルク変化量（第２アシストトルク）を算出する。即ち、トルク変化推定部３５では、時定数演算部４１が時定数マップ４１ａを用いて実回転数から時定数を算出し、算出された時定数を用いて疑似微分演算部４２が実燃料噴射量の微分値を演算する。次に、トルク変化係数演算部４４が実燃料噴射量の微分値の絶対値を演算し、更にトルク変化係数演算部４４がトルク変化係数マップ４４ａを用いて実燃料噴射量の微分値の絶対値からトルク変化係数を演算する。演算されたトルク変化係数は、疑似微分演算部４２によって演算された一次遅れの要素を含む値に基づいて演算されているため、図４のトルク変化係数のグラフに示されているように一次遅れの応答性をもって増加する（図４のトルク変化係数のグラフの時刻ｔ１～ｔ２参照）。なお、演算されたトルク変化係数は、正の値として表され、実燃料噴射量を時間と共に一定の増加率（即ち、比例定数）で増加させると一次遅れ応答で変化する。 Further, the torque change estimation unit 35 of the control device 30 calculates a torque change coefficient based on the calculated actual rotational speed and the actual fuel injection amount, and further calculates a torque change amount (second assist torque). That is, in the torque change estimation unit 35, the time constant calculation unit 41 calculates a time constant from the actual rotational speed using the time constant map 41a, and the pseudo-differential calculation unit 42 uses the calculated time constant to calculate the actual fuel injection amount. The derivative value of is calculated. Next, the torque change coefficient calculation unit 44 calculates the absolute value of the differential value of the actual fuel injection amount, and the torque change coefficient calculation unit 44 further uses the torque change coefficient map 44a to calculate the absolute value of the differential value of the actual fuel injection amount. The torque change coefficient is calculated from Since the calculated torque change coefficient is calculated based on the value including the element of the first-order lag calculated by the pseudo-differential calculation unit 42, the first-order lag as shown in the torque change coefficient graph of FIG. (See times t1 to t2 in the graph of the torque change coefficient in FIG. 4). The calculated torque change coefficient is expressed as a positive value. When the actual fuel injection amount is increased with time at a constant increase rate (that is, a proportional constant), the torque change coefficient changes with a first-order lag response.
　疑似微分演算部４２は、演算の度に時定数を変更することによって、単位回転数毎の実燃料噴射量の変化率を演算し、トルク変化量演算部４７は、この変化率と実トルクとに基づいて単位回転数毎の出力トルクの変化量を演算している。というのも、実燃料噴射量の変化は、供給直後の燃焼時だけでなくその後の数回の燃焼にわたってエンジンＥの燃焼状態に影響を与える。即ち、時間ではなく燃焼回数を経ることによって、実燃料噴射量の変化による燃焼状態への影響が小さくなる。従って、実燃料噴射量が目標燃料噴射量に達した後も燃焼状態の悪化が止まらずにトルクが低下し、エンジンＥにて所定回数の燃焼（即ち、所定回数の回転）が行われた後、燃焼状態が改善される。このように、エンジンＥの燃焼状態は、時間よりも燃焼回数（即ち、回転数）に応じて変化している。これを鑑みて、疑似微分演算部４２は、単位回転数毎の実燃料噴射量の変化率を演算している。また、実燃料噴射量の変化率を演算する際に疑似微分が用いられることによって、実燃料噴射量が目標燃料噴射量に達して一定となった後も実燃料噴射量の変化率としてゼロより大きい値が算出され、その結果、トルク変化係数もゼロより大きい値となる。その後トルク変化係数がゼロに向かって減少している（図４のトルク変化係数のグラフの時刻ｔ２～ｔ３参照）。つまり、トルク変化推定部３５は、実燃料噴射量が目標燃料噴射量に達して一定となった後のトルク変化係数及びトルク変化量までをも考慮している。 The pseudo differential calculation unit 42 calculates the rate of change of the actual fuel injection amount for each unit speed by changing the time constant for each calculation, and the torque change amount calculation unit 47 calculates the change rate and the actual torque. Based on the above, the amount of change in the output torque for each unit speed is calculated. This is because the change in the actual fuel injection amount affects the combustion state of the engine E not only at the time of combustion immediately after supply but also over several subsequent combustions. That is, the influence on the combustion state due to the change in the actual fuel injection amount is reduced by passing the number of combustions instead of the time. Therefore, after the actual fuel injection amount reaches the target fuel injection amount, the deterioration of the combustion state does not stop and the torque decreases, and after the engine E performs a predetermined number of combustions (that is, a predetermined number of rotations). , The combustion state is improved. Thus, the combustion state of the engine E changes according to the number of combustions (that is, the number of revolutions) rather than the time. In view of this, the pseudo-differential calculation unit 42 calculates the rate of change of the actual fuel injection amount for each unit speed. In addition, by using a pseudo-differential when calculating the rate of change of the actual fuel injection amount, the rate of change of the actual fuel injection amount becomes zero from zero even after the actual fuel injection amount reaches the target fuel injection amount and becomes constant. A large value is calculated, and as a result, the torque change coefficient becomes a value larger than zero. Thereafter, the torque change coefficient decreases toward zero (see times t2 to t3 in the torque change coefficient graph of FIG. 4). That is, the torque change estimation unit 35 takes into account the torque change coefficient and the torque change amount after the actual fuel injection amount reaches the target fuel injection amount and becomes constant.
　このように時間単位ではなく回転数単位で出力トルクの変化を演算するので、時間単位で演算する場合に比べてエンジンＥの出力トルクの低下をより正確に推定することができる。これにより、燃焼悪化による出力トルクの低下により回転数が過度に低下することを防ぐことができ、それに伴うエンジンの燃費の低下を抑えることができる。なお、トルク変化係数は、時間ではなくエンジンＥでの燃焼回数に応じて演算されるので、時刻ｔ２～ｔ３の時間間隔は実回転数の値に基づいている。疑似微分演算部４２は、時定数を実回転数に応じて変更するので、時刻ｔ２～ｔ３におけるトルク低下係数も詳細に演算することができる。これによりトルク変化推定部３５では、より正確なトルク変化係数及びトルク変化量を推定することができる。 As described above, since the change in the output torque is calculated not in time units but in rotation speed units, it is possible to estimate the decrease in output torque of the engine E more accurately than in the case of calculation in time units. As a result, it is possible to prevent the rotational speed from excessively decreasing due to a decrease in output torque due to deterioration in combustion, and to suppress a decrease in fuel consumption of the engine that accompanies it. Since the torque change coefficient is calculated not according to the time but according to the number of combustions in the engine E, the time interval between times t2 and t3 is based on the value of the actual rotational speed. Since the pseudo-differential calculation unit 42 changes the time constant according to the actual rotational speed, the torque reduction coefficient at times t2 to t3 can be calculated in detail. As a result, the torque change estimation unit 35 can estimate a more accurate torque change coefficient and torque change amount.
　補正係数演算部４６では、トルク変化係数の演算に並行して補正係数を演算する。即ち、補正係数演算部４６は、演算された実回転数及び実燃料噴射量の各々に基づいて第１補正係数及び第２補正係数を夫々算出し、更に第１補正係数及び第２補正係数に基づいて補正係数を算出する。トルク変化率演算部４５は、演算された補正係数及びトルク変化係数に基づいてトルク変化率を演算し、更にトルク変化量演算部４７がトルク変化率及び実トルクに基づいてトルク変化量を演算する。このようにして演算されるトルク変化量は、図４のトルク変化量に示すように時間経過と共に増加して時刻ｔ２でピークとなって、時刻ｔ２から時刻ｔ３にかけてエンジンＥでの燃焼状態が改善するに伴い急激に減少するようになっている。なお、図４のトルク変化量は、低下するトルク量を正として表している。このようにトルク変化推定部３５は、トルク変化量を推定し、推定されたトルク変化量は、第２アシストトルク演算部３６で用いられる。第２アシストトルク演算部３６は、このトルク変化量によって第２アシストトルクを演算する。 The correction coefficient calculation unit 46 calculates the correction coefficient in parallel with the calculation of the torque change coefficient. That is, the correction coefficient calculator 46 calculates the first correction coefficient and the second correction coefficient based on the calculated actual rotational speed and actual fuel injection amount, respectively, and further calculates the first correction coefficient and the second correction coefficient. Based on this, a correction coefficient is calculated. The torque change rate calculation unit 45 calculates the torque change rate based on the calculated correction coefficient and torque change coefficient, and the torque change amount calculation unit 47 calculates the torque change amount based on the torque change rate and the actual torque. . The torque change amount calculated in this way increases with time as shown in the torque change amount in FIG. 4 and peaks at time t2, and the combustion state in the engine E improves from time t2 to time t3. As it happens, it decreases rapidly. In addition, the torque change amount of FIG. 4 represents the torque amount to reduce as positive. Thus, the torque change estimation unit 35 estimates the torque change amount, and the estimated torque change amount is used by the second assist torque calculation unit 36. The second assist torque calculator 36 calculates the second assist torque based on this torque change amount.
　第２アシストトルク演算部３６は、疑似微分演算部４２で演算された実燃料噴射量の微分値がゼロ以上となる場合は、乗算係数として第１所定値（例えば、１）を選択し、実燃料噴射量の微分値がゼロ未満となる場合は、乗算係数として第２所定値（例えば、０）を選択する。第２アシストトルク演算部３６は、この乗算係数をトルク変化量に乗算して第２アシストトルクを演算する。駆動制御部３７は、演算された第１アシストトルク及び第２アシストトルクを加算してアシストトルクを算出する。算出されたアシストトルクは、図４のアシストトルクのグラフに示すように変化し、目標トルクの不足分（目標トルクから実トルクを差し引いた不足分のトルクに相当する差分トルク）を補いつつ、更にトルク変化量（実燃料噴射量の変化に伴って低下したトルクの不足分に相当する変化トルク）も補うようになっている。それ故、油圧ポンプ１７の負荷が急激に増加した際に最も大きくなり、実燃料噴射量の増加と共に減少するようになっている（図４のトルク変化量のグラフの時刻ｔ１～ｔ２参照）。また、差分トルク（第１アシストトルク）がゼロとなった後もエンジンＥの燃焼状態の遷移に起因する出力トルクの変化を補うべく、時刻ｔ２～時刻ｔ３までの間、変化トルク（第２アシストトルク）がアシストトルクとして算出される。制御装置３０は、演算されたアシストトルクに基づいてインバータ２２を制御して電動機２０にアシストトルクを出力させるようになっている。 The second assist torque calculation unit 36 selects a first predetermined value (for example, 1) as a multiplication coefficient when the differential value of the actual fuel injection amount calculated by the pseudo-differential calculation unit 42 is zero or more. When the differential value of the fuel injection amount is less than zero, a second predetermined value (for example, 0) is selected as the multiplication coefficient. The second assist torque calculator 36 calculates the second assist torque by multiplying the torque change amount by this multiplication coefficient. The drive control unit 37 calculates the assist torque by adding the calculated first assist torque and second assist torque. The calculated assist torque changes as shown in the assist torque graph of FIG. 4, and further compensates for the shortage of the target torque (difference torque corresponding to the shortage of the target torque minus the actual torque). A torque change amount (a change torque corresponding to a shortage of torque that decreases with a change in the actual fuel injection amount) is also compensated. Therefore, it becomes the largest when the load of the hydraulic pump 17 suddenly increases, and decreases as the actual fuel injection amount increases (see the times t1 to t2 in the graph of the torque change amount in FIG. 4). In addition, even after the differential torque (first assist torque) becomes zero, the change torque (second assist) from time t2 to time t3 in order to compensate for the change in output torque caused by the transition of the combustion state of the engine E. Torque) is calculated as the assist torque. The control device 30 controls the inverter 22 based on the calculated assist torque so that the electric motor 20 outputs the assist torque.
　このように、油圧ポンプ駆動システム１は、トルク変化推定部３５によって実燃燃料噴射量の変化に起因するエンジンＥの燃焼状態の遷移による出力トルクの変化量を事前に推定し、推定された変化量に相当する第２アシストトルクを電動機２０から出力してエンジンＥをアシストすることができる。即ち、エンジンＥの出力トルクの低下を事前に推定し、その低下分を電動機によってアシストすることができる。これにより、油圧ポンプ１７の負荷入れ時において、燃焼状態の遷移によって出力トルクが低下して回転数が過度に低下することを防ぐことができ、回転数が過度に低下することに伴う油圧ポンプの吐出流量の低下による操作性の低下を抑えることができる。 Thus, the hydraulic pump drive system 1 preliminarily estimates the amount of change in the output torque due to the transition of the combustion state of the engine E caused by the change in the actual fuel injection amount by the torque change estimation unit 35, and the estimated change The engine E can be assisted by outputting the second assist torque corresponding to the amount from the electric motor 20. That is, a decrease in the output torque of the engine E can be estimated in advance, and the decrease can be assisted by the electric motor. As a result, when the hydraulic pump 17 is loaded, it is possible to prevent the output torque from being reduced due to the transition of the combustion state and the rotational speed from being excessively decreased, and the hydraulic pump associated with the excessive decrease in the rotational speed can be prevented. A decrease in operability due to a decrease in the discharge flow rate can be suppressed.
　その後、実燃料噴射量が目標燃料噴射量まで達してエンジンＥが所定回数回転すると、エンジンＥの燃焼状態が安定し、その結果トルク変化係数が略ゼロとなる、即ちトルク変化量がゼロとなる（図４のトルク変化係数及びトルク変化量のグラフの時刻ｔ３～ｔ４参照）。そうすると、油圧ポンプ駆動システム１では、エンジンＥだけでポンプが駆動され、電動機２０からのアシストがなくなる（図４の時刻ｔ３～ｔ４参照）。 Thereafter, when the actual fuel injection amount reaches the target fuel injection amount and the engine E rotates a predetermined number of times, the combustion state of the engine E becomes stable, and as a result, the torque change coefficient becomes substantially zero, that is, the torque change amount becomes zero. (See times t3 to t4 in the graph of the torque change coefficient and torque change amount in FIG. 4). Then, in the hydraulic pump drive system 1, the pump is driven only by the engine E, and the assist from the electric motor 20 is lost (see times t3 to t4 in FIG. 4).
　次に、操作具の操作が止まって（即ち、操作具が中立位置まで戻されて）油圧ポンプ１７は、オンロード状態からアンロード状態に切替わると、油圧ポンプ１７の負荷が小さくなる。油圧ポンプ１７では、いわゆる負荷抜けが生じる（図４のポンプ負荷のグラフの時刻ｔ４参照）。負荷抜けが生じた際、エンジンＥの実回転数が目標回転数より大きくなり、制御装置３０は、実回転数と目標回転数との差から目標燃料噴射量を演算する。エンジンＥの実回転数が目標回転数より大きいので、制御装置３０は、目標燃料噴射量を演算する際、実回転数を目標回転数にするべく目標燃料噴射量を減少させる。そのため、噴射量制限部３２は、目標燃料噴射量の増加率が所定値以上でないと判定し、目標燃料噴射量を実燃料噴射量として算出する（図４の実燃料噴射量のグラフの時刻ｔ４～ｔ５参照）。これにより、目標トルク演算部３１及び実トルク演算部３３の各々で演算される目標トルク及び実トルクが一致するようになり、第１アシストトルク演算部３４によって第１アシストトルクがゼロと算出される（図４の第１アシストトルクのグラフの時刻ｔ４～ｔ５参照）。また、トルク変化推定部３５では、操作具が操作された場合と同様に、演算された実回転数及び実燃料噴射量に基づいてトルク変化係数及びトルク変化量を推定する（図４のトルク変化係数及びトルク変化量のグラフの時刻ｔ４～ｔ５参照）。他方、実燃料噴射量の微分値がゼロ未満となるので、第２アシストトルク演算部３６は、乗算係数としてゼロを選択する。第２アシストトルク演算部３６は、この乗算係数をトルク変化量に乗算して第２アシストトルクを算出するので、第２アシストトルクはゼロとなる。 Next, when the operation of the operation tool is stopped (that is, the operation tool is returned to the neutral position) and the hydraulic pump 17 is switched from the on-load state to the unload state, the load on the hydraulic pump 17 is reduced. In the hydraulic pump 17, so-called load loss occurs (see time t4 in the pump load graph of FIG. 4). When the load loss occurs, the actual rotational speed of the engine E becomes larger than the target rotational speed, and the control device 30 calculates the target fuel injection amount from the difference between the actual rotational speed and the target rotational speed. Since the actual rotational speed of the engine E is larger than the target rotational speed, the control device 30 decreases the target fuel injection amount so that the actual rotational speed becomes the target rotational speed when calculating the target fuel injection amount. Therefore, the injection amount limiting unit 32 determines that the increase rate of the target fuel injection amount is not equal to or greater than the predetermined value, and calculates the target fuel injection amount as the actual fuel injection amount (time t4 in the graph of the actual fuel injection amount in FIG. 4). To t5). Thereby, the target torque and the actual torque calculated by each of the target torque calculation unit 31 and the actual torque calculation unit 33 coincide with each other, and the first assist torque calculation unit 34 calculates the first assist torque to be zero. (See time t4 to t5 in the graph of the first assist torque in FIG. 4). Further, the torque change estimation unit 35 estimates the torque change coefficient and the torque change amount based on the calculated actual rotational speed and the actual fuel injection amount as in the case where the operation tool is operated (torque change in FIG. 4). (Refer to times t4 to t5 in the graph of coefficient and torque change amount). On the other hand, since the differential value of the actual fuel injection amount is less than zero, the second assist torque calculator 36 selects zero as the multiplication coefficient. The second assist torque calculator 36 calculates the second assist torque by multiplying the torque change amount by this multiplication coefficient, so the second assist torque becomes zero.
　このように油圧ポンプ１７の負荷抜け時は、エンジンＥの実回転数が急激に上昇し（図４のエンジン回転数のグラフの時刻ｔ４～ｔ５参照）、それを低下させるべく急激に目標燃料噴射量が低下する。その場合でも、実回転数が急激に低下する場合と同様にエンジンＥの燃焼状態の遷移が生じてトルク変化（具体的にはトルク低下）が生じる。しかし、負荷抜け時は、油圧ポンプ１７の出力トルクを下げる必要がある。そのため、エンジンＥの実回転数が下げることを妨げるようなアシストトルクが電動機２０から発生することを防ぐのがよい。そのため、油圧ポンプ駆動システム１では、実燃料噴射量の微分値がゼロ未満となる場合に第２アシストトルク演算部３６における乗算係数をゼロとして負荷抜け時にアシストトルクが発生しないようになっている。これにより、エンジンで出力トルクを低下させている際に電動機によって無駄にエネルギーが消費されることを防ぐことができる。 As described above, when the load of the hydraulic pump 17 is released, the actual rotational speed of the engine E rapidly increases (see times t4 to t5 in the graph of the engine rotational speed in FIG. 4), and the target fuel injection is rapidly performed to decrease it. The amount is reduced. Even in such a case, the transition of the combustion state of the engine E occurs as in the case where the actual rotational speed sharply decreases, resulting in a torque change (specifically, a torque decrease). However, when the load is lost, it is necessary to reduce the output torque of the hydraulic pump 17. Therefore, it is preferable to prevent the assist torque from being generated from the electric motor 20 so as to prevent the actual rotational speed of the engine E from being lowered. Therefore, in the hydraulic pump drive system 1, when the differential value of the actual fuel injection amount is less than zero, the multiplication coefficient in the second assist torque calculator 36 is set to zero so that assist torque is not generated when the load is released. Thereby, when the output torque is reduced by the engine, it is possible to prevent wasteful consumption of energy by the electric motor.
　また、後述するように、噴射量制限部３２では、減少率制限を行わないレートリミット機能を有しているので、第１アシストトルク演算部３４で第１アシストトルクがゼロとなっている。それ故、電動機で回生力が発生することがなく、エンジンＥの燃費を向上させることができる。 As will be described later, since the injection amount limiting unit 32 has a rate limiting function that does not limit the decrease rate, the first assist torque calculating unit 34 sets the first assist torque to zero. Therefore, regenerative power is not generated in the electric motor, and the fuel efficiency of the engine E can be improved.
　［その他の実施形態について］
　本実施形態の油圧ポンプ駆動システム１では、減少率制限を行わないレートリミット機能を噴射量制限部３２が有し、且つ実燃料噴射量の微分値がゼロ未満の際に第２アシストトルクをゼロとする機能を第２アシストトルク演算部３６が有している。以下では、これらの機能を有しない他の実施形態の油圧ポンプ駆動システム１Ａの動作について、図５を参照しながら説明する。なお、油圧ポンプ駆動システム１Ａの構成は、前述の機能以外は油圧ポンプ駆動システム１と同じであるので、図１乃至図３を参照する。図５には、図４と同様に、紙面上から順にポンプ負荷（油圧ポンプ１７の負荷）、エンジン回転数（実回転数）、目標燃料噴射量、実燃料噴射量、第１アシストトルク、トルク変化係数、トルク変化量、及びアシストトルクの経時変化を示している。なお、図５の横軸が時間であり、縦軸が各種値を示している。 [Other embodiments]
In the hydraulic pump drive system 1 of this embodiment, the injection amount limiting unit 32 has a rate limit function that does not limit the decrease rate, and the second assist torque is zero when the differential value of the actual fuel injection amount is less than zero. The second assist torque calculator 36 has a function of Below, operation | movement of 1 A of hydraulic pump drive systems of 1st Embodiment which does not have these functions is demonstrated, referring FIG. The configuration of the hydraulic pump drive system 1A is the same as that of the hydraulic pump drive system 1 except for the functions described above, and therefore, FIG. 1 to FIG. 3 are referred to. In FIG. 5, similarly to FIG. 4, the pump load (load of the hydraulic pump 17), the engine speed (actual speed), the target fuel injection amount, the actual fuel injection amount, the first assist torque, and the torque in order from the paper surface. A change coefficient, a torque change amount, and an assist torque change with time are shown. In FIG. 5, the horizontal axis represents time, and the vertical axis represents various values.
　他の実施形態の油圧ポンプ駆動システム１Ａでは、負荷入り時の各種値の変化が油圧ポンプ駆動システム１と同じであり、負荷抜け時の各種値の変化が油圧ポンプ駆動システム１と異なる。例えば、油圧ポンプ駆動システム１Ａにおける実燃料噴射量及び第１アシストトルクは図５に示すように変化する。即ち、負荷抜け時において、実燃料噴射量は、時間に比例して段階的に減少し（図５の実燃料噴射量の時刻ｔ６～ｔ７参照）、第１アシストトルクは、回生力として演算される（図５の第１アシストトルクの時刻ｔ６～ｔ７参照）。他方、エンジンＥでは、実燃料噴射量の減少に伴ってトルク低下が生じる。そのため、第２アシストトルク演算部３６は、これを補うべくトルク変化推定部３５によって推定されるトルク変化量に基づいて第２アシストトルクを演算する。このようにして演算された第１アシストトルク及び第２アシストトルクは、駆動制御部３７にて加算される。 In the hydraulic pump drive system 1A according to another embodiment, the change of various values when the load is applied is the same as that of the hydraulic pump drive system 1, and the change of the various values when the load is removed is different from the hydraulic pump drive system 1. For example, the actual fuel injection amount and the first assist torque in the hydraulic pump drive system 1A change as shown in FIG. That is, when the load is lost, the actual fuel injection amount decreases stepwise in proportion to the time (see times t6 to t7 of the actual fuel injection amount in FIG. 5), and the first assist torque is calculated as the regenerative force. (Refer to times t6 to t7 of the first assist torque in FIG. 5). On the other hand, in the engine E, the torque is reduced as the actual fuel injection amount is reduced. Therefore, the second assist torque calculator 36 calculates the second assist torque based on the torque change amount estimated by the torque change estimator 35 to compensate for this. The first assist torque and the second assist torque calculated in this way are added by the drive control unit 37.
　このように、油圧ポンプ駆動システム１Ａでは、負荷抜け時においてエンジンＥをアシストしながら第１アシストトルクによる無駄な回生が行われる。それ故、システムとしての効率が低下する。また、油圧ポンプ駆動システム１Ａでは、負荷抜け時において、実燃料噴射量を減少させる際のエンジンＥの燃料状態の遷移によるトルク低下を補うべく、第２アシストトルクが出力される。そのため、ポンプ負荷を速やかに低下させたいにもかかわらず、エンジンＥの出力トルクが無駄にアシストされることになる。これらを避けるべく、油圧ポンプ駆動システム１では、噴射量制限部３２は減少率制限なしのレートリミット機能を有し、また第２アシストトルク演算部３６は、実燃料噴射量の微分値を考慮して第２アシストトルクを演算するようになっている。即ち、噴射量制限部３２の減少率制限なしのレートリミット機能は、負荷抜け時の第１アシストトルクによる無駄な回生が行われることを防ぎ、第２アシストトルク演算部３６は、実燃料噴射量の微分値を考慮して第２アシストトルクを演算することで、負荷抜け時にエンジンＥの出力トルクを速やかに低下させることを可能にしている。ここで、油圧ポンプ駆動システム１の説明は、減少率制限なしのレートリミット機能及び実燃料噴射量の微分値を考慮して第２アシストトルクを演算することが好ましい機能であることを示すものであって、必ずしもこれらの機能を備えるものを除外するものではない。即ち、油圧ポンプ駆動システム１Ａもまた本件発明に係る一実施形態である。 Thus, in the hydraulic pump drive system 1A, useless regeneration by the first assist torque is performed while assisting the engine E when the load is released. Therefore, the efficiency of the system is lowered. In the hydraulic pump drive system 1A, the second assist torque is output in order to compensate for the torque drop due to the transition of the fuel state of the engine E when the actual fuel injection amount is reduced when the load is released. Therefore, the output torque of the engine E is unnecessarily assisted although it is desired to quickly reduce the pump load. In order to avoid these, in the hydraulic pump drive system 1, the injection amount limiting unit 32 has a rate limiting function without limiting the reduction rate, and the second assist torque calculating unit 36 takes into account the differential value of the actual fuel injection amount. Thus, the second assist torque is calculated. That is, the rate limit function without the reduction rate limitation of the injection amount limiting unit 32 prevents unnecessary regeneration due to the first assist torque when the load is lost, and the second assist torque calculating unit 36 determines the actual fuel injection amount. By calculating the second assist torque in consideration of the differential value, it is possible to quickly reduce the output torque of the engine E when the load is lost. Here, the description of the hydraulic pump drive system 1 shows that it is a preferable function to calculate the second assist torque in consideration of the rate limit function without the reduction rate limit and the differential value of the actual fuel injection amount. Thus, it does not necessarily exclude those having these functions. That is, the hydraulic pump drive system 1A is also an embodiment according to the present invention.
　［その他の構成について］
　本実施形態の油圧ポンプ駆動システム1、１Ａでは、実回転数に基づいて疑似微分の時定数を変化させることで単位回転数当たりのトルク（例えば、１回転数当たりのトルク）変化量を疑似的に演算している。この方法以外に、実際に単位回転数毎に疑似微分の演算を行って、実際に単位回転毎のトルクの変化量を求めるようにしてもよい。即ち、実回転数が大きくなればなるほどトルクの変化量を演算する間隔が短くなり、実回転数が小さくなればなるほどトルクの変化量を演算する間隔が長くなる。これにより、単位回転数当たりのトルクの変化量を推定することができる。 [Other configuration]
In the hydraulic pump drive systems 1 and 1A of the present embodiment, the amount of change in torque per unit revolution (for example, torque per revolution) is simulated by changing the time constant of pseudo differentiation based on the actual revolution. Has been calculated. In addition to this method, a pseudo differential calculation may be actually performed for each unit rotation speed, and the amount of torque change for each unit rotation may be actually obtained. That is, as the actual rotational speed increases, the interval for calculating the torque change amount becomes shorter, and as the actual rotational speed decreases, the interval for calculating the torque change amount becomes longer. Thereby, the amount of change in torque per unit rotation speed can be estimated.
　油圧ポンプ駆動システム１，１Ａでは、第１アシストトルクと第２アシストトルクとを演算してそれらを加えてアシストトルクとしているが、第１アシストトルクと第２アシストトルクの何れか一方だけをアシストトルクとしてもよい。即ち、油圧ポンプ駆動システム１，１Ａでは、１アシストトルク及び第２アシストトルクの両方を演算する機能を必ずしも備えている必要はなく、目標トルク演算部３１及び第１アシストトルク演算部３４を備えていなくてもよい。目標トルク演算部３１、噴射量制限部３２及び第１アシストトルク演算部３４を備えていない場合は、目標燃料噴射量演算部３８が実燃料噴射量演算部として機能する。また、トルク変化推定部３５は、前述のような推定方法に限らず、実燃料噴射量の変化によるエンジンＥの出力トルクの変化を推定できる方法であればよい。 In the hydraulic pump drive systems 1 and 1A, the first assist torque and the second assist torque are calculated and added to obtain the assist torque, but only one of the first assist torque and the second assist torque is used as the assist torque. It is good. That is, the hydraulic pump drive systems 1 and 1A do not necessarily have the function of calculating both the first assist torque and the second assist torque, and include the target torque calculation unit 31 and the first assist torque calculation unit 34. It does not have to be. When the target torque calculating unit 31, the injection amount limiting unit 32, and the first assist torque calculating unit 34 are not provided, the target fuel injection amount calculating unit 38 functions as an actual fuel injection amount calculating unit. The torque change estimation unit 35 is not limited to the estimation method as described above, and any method that can estimate the change in the output torque of the engine E due to the change in the actual fuel injection amount may be used.
　また、油圧ポンプ駆動システム１，１Ａが実装される建設機械は、油圧ショベルに限定されず、クレーンやドーザ等の他の建設機械であってもよく、油圧アクチュエータを備えている建設機械であればよい。また、油圧ポンプ駆動システム１，１Ａでは、液圧ポンプの例として油圧ポンプを挙げたが、液圧ポンプは、油圧ポンプに限定されず水等の液体を吐出するポンプであればよい。 The construction machine on which the hydraulic pump drive systems 1 and 1A are mounted is not limited to a hydraulic excavator, and may be another construction machine such as a crane or a dozer, as long as it is a construction machine provided with a hydraulic actuator. Good. In the hydraulic pump drive systems 1 and 1A, the hydraulic pump is described as an example of the hydraulic pump. However, the hydraulic pump is not limited to the hydraulic pump and may be a pump that discharges liquid such as water.
　上記説明から、当業者にとっては、本発明の多くの改良や他の実施形態が明らかである。従って、上記説明は、例示としてのみ解釈されるべきであり、本発明を実行する最良の態様を当業者に教示する目的で提供されたものである。本発明の精神を逸脱することなく、その構造及び／又は機能の詳細を実質的に変更できる。 From the above description, many modifications and other embodiments of the present invention are apparent to persons skilled in the art. Accordingly, the foregoing description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of the structure and / or function may be substantially changed without departing from the spirit of the invention.
　１，１Ａ　油圧ポンプ駆動システム
　１７　油圧ポンプ
　１７ａ　回転軸
　２０　電動機
　２３　回転数センサ
　３０　制御装置
　３１　目標トルク演算部
　３２　噴射量制限部（実燃料噴射量演算部）
　３３　実トルク演算部
　３４　第１アシストトルク演算部（差分トルク演算部）
　３５　トルク変化推定部
　３６　第２アシストトルク演算部（変化トルク演算部）
　３８　目標燃料噴射量演算部
　３７　駆動制御部
　４１　時定数演算部
　４２　疑似微分演算部
　４４　トルク変化係数演算部
　４５　トルク変化率演算部
　４６　補正係数演算部
　４７　トルク変化量演算部 DESCRIPTION OF SYMBOLS 1,1A Hydraulic pump drive system 17 Hydraulic pump 17a Rotating shaft 20 Electric motor 23 Rotation speed sensor 30 Control apparatus 31 Target torque calculating part 32 Injection amount restriction | limiting part (actual fuel injection amount calculating part)
33 Actual torque calculator 34 First assist torque calculator (difference torque calculator)
35 Torque change estimation unit 36 Second assist torque calculation unit (change torque calculation unit)
38 Target fuel injection amount calculation section 37 Drive control section 41 Time constant calculation section 42 Pseudo-differential calculation section 44 Torque change coefficient calculation section 45 Torque change rate calculation section 46 Correction coefficient calculation section 47 Torque change amount calculation section

Claims (11)

  1. 　液圧ポンプの回転軸を回転駆動するエンジンと、
    　前記回転軸の回転駆動をアシスト可能な電動機と、
    　前記回転軸の実回転数を検出する回転数センサと、
    　前記電動機を制御する制御装置とを備え、
    　前記制御装置は、目標燃料噴射量演算部と、噴射量制限部と、実トルク演算部と、目標トルク演算部と、差分トルク演算部と、駆動制御部と、を有し、
    　前記目標燃料噴射量演算部は、前記回転数センサで検出される前記実回転数と目標回転数とに基づいて目標燃料噴射量を演算し、
    　前記噴射量制限部は、前記目標燃料噴射量に基づいて実燃料噴射量を演算する際に、前記目標燃料噴射量まで段階的に実燃料噴射量を増加させる機能を有し、増加させる際の実燃料噴射量の時間変化率が所定値以下となるように実燃料噴射量を決定し、
    　前記実トルク演算部は、前記実回転数と前記噴射量制限部で決定される実燃料噴射量とに基づいて前記エンジンで出力される実トルクを演算し、
    　前記目標トルク演算部は、前記実回転数と前記目標燃料噴射量とに基づいて、前記回転軸に与えるべき目標トルクを演算し、
    　前記差分トルク演算部は、前記目標トルクに対して前記実トルクで不足する差分トルクを演算し、
    　前記駆動制御部は、前記差分トルクを出力させるように前記電動機を制御する、液圧ポンプ駆動システム。     An engine that rotationally drives the rotary shaft of the hydraulic pump;
    An electric motor capable of assisting rotation driving of the rotating shaft;
    A rotational speed sensor for detecting an actual rotational speed of the rotational shaft;
    A control device for controlling the electric motor,
    The control device includes a target fuel injection amount calculation unit, an injection amount restriction unit, an actual torque calculation unit, a target torque calculation unit, a differential torque calculation unit, and a drive control unit,
    The target fuel injection amount calculation unit calculates a target fuel injection amount based on the actual rotation speed and the target rotation speed detected by the rotation speed sensor,
    The injection amount limiting unit has a function of increasing the actual fuel injection amount step by step up to the target fuel injection amount when calculating the actual fuel injection amount based on the target fuel injection amount. The actual fuel injection amount is determined so that the rate of change over time of the actual fuel injection amount is a predetermined value or less,
    The actual torque calculation unit calculates an actual torque output from the engine based on the actual rotation speed and the actual fuel injection amount determined by the injection amount limiting unit,
    The target torque calculator calculates a target torque to be applied to the rotary shaft based on the actual rotational speed and the target fuel injection amount,
    The differential torque calculator calculates a differential torque that is insufficient with the actual torque with respect to the target torque,
    The drive control unit is a hydraulic pump drive system that controls the electric motor to output the differential torque.
  2. 　前記噴射量制限部は、前記目標燃料噴射量が減少している場合、前記目標燃料噴射量を前記実燃料噴射量とする、請求項１に記載の液圧ポンプの駆動システム。 2. The hydraulic pump drive system according to claim 1, wherein when the target fuel injection amount is decreased, the injection amount limiting unit sets the target fuel injection amount as the actual fuel injection amount.
  3. 　前記噴射量制限部は、前記目標燃料噴射量に基づいて前記実燃料噴射量を演算する際に、前記目標燃料噴射量が増加している場合、経過時間に比例して変化させる変化規則に基づいて前記実燃料噴射量を段階的に増加させる、請求項1又は２に記載の液圧ポンプの駆動システム。 When the target fuel injection amount is increased when the actual fuel injection amount is calculated based on the target fuel injection amount, the injection amount limiting unit is based on a change rule that changes in proportion to the elapsed time. The hydraulic pump drive system according to claim 1, wherein the actual fuel injection amount is increased stepwise.
  4. 　前記噴射量制限部は、前記目標燃料噴射量に基づいて前記実燃料噴射量を演算する際に、前記目標燃料噴射量が増加している場合、経過時間に対して一次遅れさせる変化規則に基づいて前記実燃料噴射量を段階的に増加させる、請求項1又は２に記載の液圧ポンプの駆動システム。 When the target fuel injection amount is increased when calculating the actual fuel injection amount based on the target fuel injection amount, the injection amount limiting unit is based on a change rule that causes a primary delay with respect to the elapsed time. The hydraulic pump drive system according to claim 1, wherein the actual fuel injection amount is increased stepwise.
  5. 　前記制御装置は、トルク変化推定部と、変化トルク演算部と、を有し、
    　前記トルク変化推定部は、前記実燃料噴射量と前記実回転数とに基づいて前記エンジンの出力トルクの変化量を推定し、
    　前記変化トルク演算部は、前記トルク変化推定部で演算される前記出力トルクの変化量に基づいて前記回転軸の回転駆動をアシストするように変化トルクを演算し、
    　前記駆動制御部は、前記差分トルクに前記変化トルクを加えたトルクを出力させるように前記電動機を制御する、請求項１乃至４の何れか１つに記載の液圧ポンプの駆動システム。     The control device includes a torque change estimation unit and a change torque calculation unit,
    The torque change estimation unit estimates a change amount of the output torque of the engine based on the actual fuel injection amount and the actual rotational speed,
    The change torque calculation unit calculates a change torque so as to assist rotation driving of the rotary shaft based on a change amount of the output torque calculated by the torque change estimation unit,
    5. The hydraulic pump drive system according to claim 1, wherein the drive control unit controls the electric motor to output a torque obtained by adding the change torque to the differential torque. 6.
  6. 　前記トルク変化推定部は、前記実燃料噴射量に基づいて前記エンジンの単位回転数当たりの前記出力トルクの変化率を推定し、前記実トルクと前記変化率とに基づいて前記出力トルクの変化量を演算する、請求項５に記載の液圧ポンプの駆動システム。 The torque change estimation unit estimates a change rate of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and changes the output torque based on the actual torque and the change rate. The hydraulic pump drive system according to claim 5, wherein
  7. 　前記トルク変化推定部は、時定数を変えられる一次遅れ要素を含む疑似微分演算部と、前記実回転数に応じて前記一次遅れ要素の時定数を演算する時定数演算部とを有し、
    　前記時定数演算部によって演算された時定数を用いた疑似微分によって前記エンジンの単位回転数当たりにおける前記実燃料噴射量の変化率を前記擬似微分演算部が算出し、前記実燃料噴射量の変化率に基づいて前記エンジンの単位回転数当たりにおける前記出力トルクの変化量を前記トルク変化推定部が推定する請求項５又は６に記載の液圧ポンプの駆動システム。     The torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed,
    The pseudo-differential calculation unit calculates the rate of change of the actual fuel injection amount per unit rotational speed of the engine by pseudo-differentiation using the time constant calculated by the time constant calculation unit, and the change of the actual fuel injection amount The hydraulic pump drive system according to claim 5 or 6, wherein the torque change estimation unit estimates a change amount of the output torque per unit revolution number of the engine based on a rate.
  8. 　前記変化トルク演算部は、前記実燃料噴射量の変化率がゼロ未満であると、前記変化トルクをゼロとする、請求項７に記載の液圧ポンプの駆動システム。 The hydraulic pump drive system according to claim 7, wherein the change torque calculation unit sets the change torque to zero when the change rate of the actual fuel injection amount is less than zero.
  9. 　液圧ポンプの回転軸を回転駆動するエンジンと、
    　前記回転軸の回転駆動をアシスト可能な電動機と、
    　前記回転軸の実回転数を検出する回転数センサと、
    　前記電動機の動きを制御する制御装置とを備え、
    　前記制御装置は、実燃料噴射量演算部と、トルク変化推定部と、変化トルク演算部と、駆動制御部と、を有し、
    　前記実燃料噴射量演算部は、前記実回転数と目標回転数とに基づいて実燃料噴射量を演算し、
    　前記トルク変化推定部は、前記実燃料噴射量と前記実回転数とに基づいて前記エンジンの出力トルクの変化量を推定し、
    　前記変化トルク演算部は、前記出力トルクの変化量に基づいて前記回転軸の回転駆動をアシストする変化トルクを演算し、
    　前記駆動制御部は、前記変化トルクを出力させるように前記電動機を制御する、液圧ポンプの駆動システム。     An engine that rotationally drives the rotary shaft of the hydraulic pump;
    An electric motor capable of assisting rotation driving of the rotating shaft;
    A rotational speed sensor for detecting an actual rotational speed of the rotational shaft;
    A control device for controlling the movement of the electric motor,
    The control device includes an actual fuel injection amount calculation unit, a torque change estimation unit, a change torque calculation unit, and a drive control unit,
    The actual fuel injection amount calculation unit calculates an actual fuel injection amount based on the actual rotation speed and the target rotation speed,
    The torque change estimation unit estimates a change amount of the output torque of the engine based on the actual fuel injection amount and the actual rotational speed,
    The change torque calculator calculates a change torque that assists the rotational drive of the rotary shaft based on the change amount of the output torque,
    The drive control unit is a hydraulic pump drive system that controls the electric motor to output the change torque.
  10. 　前記制御装置は、実トルク演算部を有し、
    　前記実トルク演算部は、前記回転数センサで検出される実回転数と前記実燃料噴射量とに基づいて前記エンジンで出力される実トルクを演算し、
    　前記トルク変化推定部は、前記実燃料噴射量に基づいて前記エンジンの単位回転数当たりの前記出力トルクの変化率を推定し、前記実トルクと前記変化率とに基づいて前記出力トルクの変化量を演算する、請求項９に記載の液圧ポンプの駆動システム。     The control device has an actual torque calculation unit,
    The actual torque calculation unit calculates an actual torque output from the engine based on an actual rotation speed detected by the rotation speed sensor and the actual fuel injection amount,
    The torque change estimation unit estimates a change rate of the output torque per unit revolution number of the engine based on the actual fuel injection amount, and changes the output torque based on the actual torque and the change rate. The hydraulic pump drive system according to claim 9, wherein:
  11. 　前記トルク変化推定部は、時定数を変えられる一次遅れ要素を含む疑似微分演算部と、前記実回転数に応じて前記一次遅れ要素の時定数を演算する時定数演算部とを有し、
    　前記時定数演算部によって演算された時定数を用いた疑似微分によって前記エンジンの単位回転数当たりの前記実燃料噴射量の変化率を前記擬似微分演算部が算出し、前記実燃料噴射量の変化率に基づいて前記出力トルクの前記エンジンの単位回転数当たりの変化量を前記トルク変化推定部が推定する請求項９又は１０に記載の液圧ポンプの駆動システム。
          The torque change estimation unit includes a pseudo-differential calculation unit including a first-order lag element whose time constant can be changed, and a time constant calculation unit that calculates a time constant of the first-order lag element according to the actual rotational speed,
    The pseudo-differential calculation unit calculates a change rate of the actual fuel injection amount per unit revolution of the engine by pseudo-differentiation using the time constant calculated by the time constant calculation unit, and the change of the actual fuel injection amount The hydraulic pump drive system according to claim 9 or 10, wherein the torque change estimation unit estimates a change amount of the output torque per unit revolution of the engine based on a rate.
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