JP5166806B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device used when a hydraulic pump is driven by an engine.

  Conventionally, diesel engines are mounted on construction machines such as hydraulic excavators, bulldozers, dump trucks, and wheel loaders.

  A schematic configuration of a conventional construction machine 100 will be described with reference to FIG. As shown in FIG. 26, the construction machine 100 drives the hydraulic pump 3 using the engine 2 which is a diesel engine as a drive source. As the hydraulic pump 3, a variable displacement hydraulic pump is used, and the capacity q (cc / rev) is changed by changing the tilt angle of the swash plate 3a. Pressure oil discharged from the hydraulic pump 3 at the discharge pressure PRP and the flow rate Q (cc / min) is supplied to the hydraulic actuators 31 to 36 such as the boom cylinder 31 via the operation valves 21 to 26. The operation valves 21 to 26 are actuated by operating the operation levers 41 and 42. By supplying pressure oil to each hydraulic actuator 31-36, each hydraulic actuator 31-36 is driven, and a working machine including a boom, an arm, and a bucket connected to each hydraulic actuator 31-36, a lower traveling body, The upper swing body is activated. While the construction machine 100 is in operation, the load applied to the work machine, the lower traveling body, and the upper turning body constantly changes according to the excavated soil quality, the traveling path gradient, and the like. In accordance with this, the load on the hydraulic equipment (hydraulic pump 3) (hereinafter referred to as oil machine load), that is, the load applied to the engine 2 changes.

  The output P (horsepower; kw) of the engine 2 is controlled by adjusting the amount of fuel injected into the cylinder. This adjustment is performed by controlling the governor 4 attached to the fuel injection pump of the engine 1. As the governor 4, an all-speed control type governor is generally used, and the engine speed n and the fuel injection amount (torque T) according to the load so that the target engine speed set by the fuel dial is maintained. ) And are adjusted. That is, the governor 4 increases or decreases the fuel injection amount so that the difference between the target rotation speed and the engine rotation speed is eliminated.

  FIG. 27 shows a torque diagram of the engine 2. The horizontal axis represents the engine speed n (rpm; rev / min), and the vertical axis represents the torque T (N · m). In FIG. 27, the region defined by the maximum torque line R indicates the performance that the engine 2 can produce. The governor 4 controls the engine 2 so that the torque T does not exceed the maximum torque line R and does not reach the exhaust smoke limit, and the engine speed n does not exceed the high idle speed nH and overspeed. At the rated point V on the maximum torque line R, the output (horsepower) P of the engine 2 becomes maximum. J indicates an equal horsepower curve in which the horsepower absorbed by the hydraulic pump 3 is equal horsepower.

  When the maximum target rotational speed is set by the fuel dial, the governor 4 adjusts the speed on the maximum speed regulation line Fe connecting the rated point V and the high idle point nH.

  As the load on the hydraulic pump 3 increases, the matching point at which the output of the engine 2 and the pump absorption horsepower balance moves to the rated point V side on the highest speed regulation line Fe. When the matching point moves to the rated point V side, the engine speed n is gradually reduced, and at the rated point V, the engine speed n becomes the rated speed.

  If the engine speed n is fixed at a substantially constant high speed in this way, there is a problem that the fuel consumption rate is large (poor) and the pump efficiency is low. The fuel consumption rate (hereinafter referred to as fuel consumption) refers to the amount of fuel consumed per hour and output of 1 kW, and is an index of the efficiency of the engine 2. The pump efficiency is the efficiency of the hydraulic pump 3 defined by volumetric efficiency and torque efficiency.

  In FIG. 27, M indicates an equal fuel consumption curve. The fuel consumption is minimized at M1 that is the valley of the equal fuel consumption curve M, and the fuel consumption increases toward the outside from the fuel consumption minimum point M1.

  As is clear from FIG. 27, the regulation line Fe corresponds to a region where the fuel consumption is relatively high on the equal fuel consumption curve M. For this reason, according to the conventional control method, fuel consumption is large (poor), which is not desirable in terms of engine efficiency.

  On the other hand, in the case of the variable displacement hydraulic pump 3, in general, when the discharge pressure PRP is the same, the larger the pump capacity q (swash plate tilt angle), the higher the volume efficiency and torque efficiency, and the higher the pump efficiency. Are known.

  As is clear from the following equation (1), if the flow rate Q of the pressure oil discharged from the hydraulic pump 3 is the same, the pump capacity q is increased as the rotational speed n of the engine 2 is decreased. Can do. For this reason, if the engine 2 is slowed down, the pump efficiency can be increased.

Q = n · q (1)
Therefore, in order to increase the pump efficiency of the hydraulic pump 3, the engine 2 may be operated in a low speed region where the rotational speed n is low.

  However, as is clear from FIG. 27, the regulation line Fe corresponds to a high speed region of the engine 2. For this reason, according to the conventional control method, there exists a problem that pump efficiency is low.

  In addition, when the engine 2 is operated on the regulation line Fe, the engine speed decreases when the load is high, which may lead to engine stall.

  Patent Document 1 discloses a control method in which the engine speed is changed according to the lever operation amount and the load, in contrast to the control method in which the engine speed is substantially fixed regardless of the load.

  In Patent Document 1, as shown in FIG. 27, a target engine operating line L0 passing through the minimum fuel consumption point M1 is set.

  Then, based on the operation amount of each operation lever 41, 42, 43, 44, etc., the required rotational speed of the hydraulic pump 3 is calculated, and the first engine required rotational speed corresponding to this pump required rotational speed is calculated. . Further, the required engine horsepower is calculated based on the operation amount of each operation lever 41, 42, 43, 44, etc., and the second required engine speed corresponding to this required engine horsepower is calculated. Here, the second required engine speed is calculated as the engine speed on the target engine operating line L0 in FIG. Then, the engine speed and the engine torque are controlled so that the larger engine target speed of the first and second engine required speeds can be obtained.

  As shown in FIG. 27, when the rotational speed of the engine 2 is controlled along the target engine operating line L0, fuel efficiency, engine efficiency, and pump efficiency are improved. This means that even when the same horsepower is output and the same required flow rate is obtained, the point pt2 on the target engine operating line L0 is the same point on the equal horsepower line J rather than matching at the point pt1 on the regulation line Fe. This is because the matching is performed at a point close to the minimum fuel consumption point M1 on the equal fuel consumption curve M because the pump displacement q is increased from high rotation and low torque to low rotation and high torque. . Further, when the engine 2 is operated in the low rotation region, noise is improved, and engine friction, pump unload loss, and the like are improved.

  In the field of construction machinery, a hybrid construction machine that assists the driving force of an engine with a generator motor is being developed, and many patent applications have already been filed.

  For example, in Patent Document 2, using FIG. 27, the engine 2 is controlled along the regulation line Fe0 corresponding to the set rotational speed set by the fuel dial. When the target rotational speed nr corresponding to the point A where the regulation line Fe0 and the target engine operating line L0 intersect is obtained, and the deviation between the engine target rotational speed nr and the current engine rotational speed n is positive, the generator motor , And the driving force of the engine 2 is assisted by the torque generated by the generator motor. When the deviation is negative, the generator motor is caused to generate power and the electric power is accumulated in the capacitor.

JP-A-11-2144 JP 2003-28071 A

  Incidentally, the invention described in Patent Document 1 estimates and calculates how much the rotational speed and horsepower the hydraulic pump 3 currently requires based on the amount of operation of each operation lever 41, 42 and the like. The target engine speed is calculated.

  However, in practice, the actual engine output corresponding to the current engine speed may not have a margin for the actual absorption horsepower of the current hydraulic pump. For this reason, even when trying to increase the engine speed to the target engine speed, the engine output has no margin for the power of the hydraulic pump's absorption horsepower, and there is insufficient power to increase the engine speed. In addition, the engine speed cannot be increased to the target engine speed, or the engine speed may increase only very slowly. As a result, there may be a problem that the work machine or the like (the lower traveling body, the upper turning body) of the construction machine 1 does not operate as intended by the operator or the operation is delayed.

  Furthermore, in the invention described in Patent Document 1, the target engine speed is determined according to the load of the hydraulic pump 3. In FIG. 27, the higher the load on the hydraulic pump 3, the more the matching point moves from B to A on the high load side on the target engine operating line L0.

  However, as described above, even if the engine speed is increased from the state where the engine 2 is matched at the point B of the low revolution to the target point A of the high revolution, at the matching point B of the low revolution, Since the absorption torque of the hydraulic pump 3 is small, even when the operation levers 41 to 44 are moved greatly at the beginning of the rise of the engine rotation, the work implements (lower traveling body, upper turning body) operate only very slowly. Sometimes. For this reason, the work implement or the like does not operate with good responsiveness to the operation levers 41 to 44, giving the operator a sense of incongruity in operation and reducing work efficiency. In many cases, the load increases after the operating levers 41 to 44 are moved greatly. When such a load increases, the operating levers 41 to 44 are newly operated to request an increase in the engine speed. There is a problem that the operation load on the operator is large.

  On the other hand, in the invention described in Patent Document 2, the matching point moves from C to A along the regulation line Fe0. The higher the load on the hydraulic pump 3, the more the matching point moves to the high load side on the regulation line Fe0.

  When moving from the low load side matching point C on the regulation line Fe0 to the high load side matching point A, the engine speed n is gradually reduced. As the engine speed n decreases, the output accumulated on the flywheel of the engine 2 momentarily goes outside, and the apparent output becomes larger than the actual output of the engine 2. For this reason, it is said that the movement of the matching point along the regulation line is originally responsive.

  However, in Patent Document 2, the target engine speed nr is uniquely determined by the setting of the fuel dial, and the engine speed n varies only slightly along the regulation line Fe0. Like the movement from the point B to the point A on the target engine operation line L0, the engine speed does not vary greatly along the target engine operation line L0 according to the load of the hydraulic pump 3. For this reason, unless the fuel dial is set, there is a problem that the engine 2 does not operate in a low rotation region, and pump efficiency, fuel consumption, and noise are deteriorated.

  The present invention has been made in view of the above, and improves the engine efficiency, pump efficiency, etc., operates the work implement etc. with good responsiveness as the operator intends, and also increases the load of the operator when the load increases. An object of the present invention is to provide an engine control device capable of reducing the load and increasing / decreasing the output.

  In order to solve the above-described problems and achieve the object, an engine control apparatus according to the present invention includes a hydraulic pump driven by the engine, a hydraulic actuator to which pressure oil discharged from the hydraulic pump is supplied, Operating means for operating each hydraulic actuator, engine target speed setting means for setting the engine target speed of the engine, and current engine torque estimated from the current engine speed and the fuel injection amount for the current engine Engine output calculation means for calculating the current engine output, engine target output calculation means for determining a target horsepower line for the engine speed and calculating an engine target output on the target horsepower line for the engine target speed, and the engine output Engine output calculated by the calculation means and the engine target output calculation means The calculated engine target output is compared and calculated, a corrected engine target speed obtained by correcting the engine target speed is obtained based on the comparison calculation result, and the engine speed is set so as to coincide with the corrected engine target speed. Engine control means for controlling the motor.

  In the engine control device according to the present invention, in the above invention, the engine target output calculation means sequentially inputs the corrected engine target speed as the engine target speed, and the input engine target speed The engine target output on the target horsepower line for the engine is sequentially calculated, and the engine control means sequentially compares and calculates the engine output calculated by the engine output calculation means and the engine target output calculated by the engine target output calculation means, The correction engine target rotation speed is sequentially updated based on the comparison calculation result, and the engine rotation speed is controlled so as to coincide with the updated correction engine target rotation speed.

  In the engine control device according to the present invention, in the above invention, the engine control means may be configured such that the engine output calculated by the engine output calculation means exceeds the engine target output calculated by the engine target output calculation means. Further, a difference engine speed corresponding to a value obtained by subtracting the engine target output from the engine output is added to the engine target speed, and the added value is obtained as the corrected engine target speed, and the corrected engine target speed is obtained. The engine speed is controlled so as to match the number.

  In the engine control device according to the present invention, in the above invention, the engine control means may be configured such that the engine output calculated by the engine output calculation means is lower than the engine target output calculated by the engine target output calculation means. Then, a difference engine speed corresponding to a value obtained by subtracting the engine output from the engine target output is subtracted from the engine target speed, and the subtracted value is obtained as the corrected engine target speed. The engine speed is controlled so as to match the number.

  In the engine control device according to the present invention, in the above invention, the engine target speed setting means calculates and sets the engine target speed of the engine according to an operation amount of the operation means. It is characterized by.

  In the engine control apparatus according to the present invention as set forth in the invention described above, the engine control means performs control so as not to lower the corrected engine target speed to the engine target speed or less.

  In the engine control device according to the present invention, in the above invention, when the engine control means is in a state where the operation means is in a state of increasing from a neutral state to a full state or being stationary after the increase, Control that does not update the target rotational speed in a decreasing direction is performed.

  The engine control device according to the present invention is the engine control device according to the above invention, wherein the engine control means is configured to control the engine target rotational speed when the operation state of the operation means is in a neutral state or a fine operation state close to neutral. Control is performed without correction.

  The engine control apparatus according to the present invention includes, in the above invention, a generator motor connected to the output shaft of the engine, a capacitor that stores electric power generated by the generator motor and supplies electric power to the generator motor. Determining means for determining whether or not to cause the generator motor to perform an engine torque assist operation, and when the determination means performs the engine torque assist operation, the engine control means corrects the previous engine target rotational speed. It is characterized by performing control that is not performed.

  Further, the engine control apparatus according to the present invention is the operation state determination means according to the above invention, wherein the operation means is determined from the non-operation state to the operation state based on an operation amount of the operation means. A second target speed setting means for setting the target engine speed to a second engine target speed higher than the low idle speed when it is determined that the operation state determination means has been switched to the operation state; And the engine control means sets the higher engine target speed of the corrected engine target speed and the second engine target speed as the corrected engine target speed, and the corrected engine target speed The engine speed is controlled so as to match the number.

  The engine control apparatus according to the present invention is characterized in that, in the above-described invention, a determination means for determining a work pattern of a plurality of hydraulic actuators from an operation amount of each operation means and a load pressure of the hydraulic pump, and a work pattern according to each work pattern. A horsepower limit value setting means for setting a horsepower limit value of the hydraulic pump, and a third target speed setting means for setting a third engine target speed in accordance with the horsepower limit value of the hydraulic pump, The engine control means controls the engine speed so that the engine target speed matches the smaller one of the corrected engine target speed and the third engine target speed.

  In the engine control device according to the present invention, the engine output calculation means calculates the current engine output from the current engine speed estimated from the current engine speed and the fuel injection amount for the current engine, and calculates the engine target output. The means determines a target horsepower line for the engine speed, calculates an engine target output on the target horsepower line for the engine target speed, and an engine control means calculates the engine output calculated by the engine output calculation means and the engine target. The engine target output calculated by the output calculating means is compared and calculated, and a corrected engine target speed obtained by correcting the engine target speed set by the engine target speed setting means is obtained based on the comparison calculation result. The engine speed is controlled to match the target speed. , It can be performed to reduce to increase or decrease of the output load of the operator upon increase in load.

  Hereinafter, an engine control apparatus and an engine and hydraulic pump control apparatus according to embodiments of the present invention will be described with reference to the drawings. In this embodiment, a case where a diesel engine and a hydraulic pump mounted on a construction machine such as a hydraulic excavator are controlled will be described.

(Embodiment 1)
FIG. 1 is a diagram showing an overall configuration of a construction machine 1 according to Embodiment 1 of the present invention. The construction machine 1 is a hydraulic excavator.

  The construction machine 1 includes an upper swing body and a lower traveling body, and the lower traveling body includes left and right crawler tracks. A work machine including a boom, an arm, and a bucket is attached to the vehicle body. The boom is operated when the boom cylinder 31 is driven, the arm is operated when the arm cylinder 32 is driven, and the bucket is operated when the bucket cylinder 33 is driven. Further, the left crawler belt and the right crawler belt rotate by driving the travel motor 36 and the travel motor 35, respectively. Also, the swing machinery is driven by driving the swing motor 34, and the upper swing body swings via a swing pinion, swing circle, and the like.

  The engine 2 is a diesel engine, and its output (horsepower; kw) is controlled by adjusting the amount of fuel injected into the cylinder. This adjustment is performed by controlling the governor attached to the fuel injection pump of the engine 2, and the engine controller 4 controls the engine including the control of the governor.

  The controller 6 outputs a rotation command value for setting the engine speed to the target speed ncom to the engine controller 4, and the engine controller 4 performs fuel so that the target speed n_com can be obtained by the target torque line L1. Increase or decrease the injection amount. Further, the engine controller 4 outputs engine data eng_data including the engine torque estimated from the engine speed of the engine 2 and the fuel injection amount to the controller 6.

  The output shaft of the engine 2 is connected to the drive shaft of the hydraulic pump 3, and the hydraulic pump 3 is driven by the rotation of the engine output shaft. The hydraulic pump 3 is a variable displacement hydraulic pump, and the capacity q (cc / rev) is changed by changing the tilt angle of the swash plate.

  Pressure oil discharged from the hydraulic pump 3 at a discharge pressure PRp and a flow rate Q (cc / min) is used for a boom operation valve 21, an arm operation valve 22, a bucket operation valve 23, and a turning operation valve 24. Are supplied to the operation valve 25 for right traveling and the operation valve 26 for left traveling, respectively. The pump discharge pressure PRp is detected by a hydraulic pressure sensor 7 and a hydraulic pressure detection signal is input to the controller 6.

  The pressure oil output from the operation valves 21 to 26 is supplied to the boom cylinder 31, the arm cylinder 32, the bucket cylinder 33, the turning motor 34, the right traveling motor 35, and the left traveling motor 36, respectively. Thereby, the boom cylinder 31, the arm cylinder 32, the bucket cylinder 33, the turning motor 34, the traveling motor 35, and the traveling motor 36 are driven, and the boom, arm, bucket, upper revolving body, and lower traveling body's right and left crawler belts. Operates.

  A right operation lever 41 for work / turning and a left operation lever 42 for work / turning are provided on the right side and the left side of the front side of the driver's seat of the construction machine 1, respectively, and the right operation lever 43 for traveling, A left operation lever 44 for traveling is provided.

  The right operation lever 41 for operation / turning is an operation lever for operating the boom and bucket. The boom and bucket are operated according to the operation direction, and the boom and bucket are operated at a speed corresponding to the operation amount. .

  The operation lever 41 is provided with a sensor 45 that detects an operation direction and an operation amount. The sensor 45 inputs a lever signal indicating the operation direction and the operation amount of the operation lever 41 to the controller 6. When the operation lever 41 is operated in the direction in which the boom is operated, the boom lever signal Lb0 indicating the boom raising operation amount and the boom lowering operation amount according to the tilt direction and the tilt amount with respect to the neutral position of the operation lever 41 is transmitted to the controller. 6 is input. When the operation lever 41 is operated in the direction in which the bucket is operated, the bucket lever signal Lbk indicating the bucket excavation operation amount and the bucket dump operation amount according to the tilt direction and the tilt amount with respect to the neutral position of the operation lever 41. Is input to the controller 6.

  When the operating lever 41 is operated in the direction in which the boom is operated, the pilot pressure (PPC pressure) PRbo corresponding to the tilting amount of the operating lever 41 is the lever tilting direction of each pilot port of the boom operating valve 21. It is added to the pilot port 21a corresponding to (the boom raising direction, the boom lowering direction).

  Similarly, when the operation lever 41 is operated in the direction in which the bucket is operated, the pilot pressure (PPC pressure) PRbk corresponding to the tilting amount of the operation lever 41 is out of the pilot ports of the bucket operation valve 23. It is added to the pilot port 23a corresponding to the lever tilting direction (bucket excavation direction, bucket dumping direction).

  The left operation lever 42 for operation / turning is an operation lever for operating the arm and the upper turning body, and operates the arm and the upper turning body according to the operation direction, and the arm at a speed according to the operation amount. Operate the upper revolving unit.

  The operation lever 42 is provided with a sensor 46 that detects an operation direction and an operation amount. The sensor 46 inputs a lever signal indicating the operation direction and the operation amount of the operation lever 42 to the controller 6. When the operation lever 42 is operated in the direction in which the arm is operated, the arm lever signal Lar indicating the arm excavation operation amount and the arm dump operation amount according to the tilt direction and the tilt amount with respect to the neutral position of the operation lever 42 is obtained from the controller. 6 is input. In addition, when the operation lever 42 is operated in a direction to operate the upper swing body, the turn lever indicating the right turn operation amount and the left turn operation amount according to the tilt direction and the tilt amount with respect to the neutral position of the operation lever 42. The signal Lsw is input to the controller 6.

  When the operation lever 42 is operated in the direction in which the arm is operated, the pilot pressure (PPC pressure) PRar corresponding to the amount of tilt of the operation lever 42 is the lever tilt direction of each pilot port of the arm operation valve 22. It is added to the pilot port 22a corresponding to (arm excavation direction, arm dump direction).

  Similarly, when the operation lever 42 is operated in the direction in which the upper swing body is operated, the pilot pressure (PPC pressure) PRsw corresponding to the tilting amount of the operation lever 42 is changed to each pilot port of the operation valve 24 for turning. Are added to the pilot port 24a corresponding to the lever tilting direction (right turning direction, left turning direction).

  The right traveling lever 43 and the left traveling lever 44 are operating levers for operating the right crawler track and the left crawler track, respectively, and operate the crawler belt according to the operation direction and at a speed corresponding to the operation amount. Activate the track.

  A pilot pressure (PPC pressure) PRtr corresponding to the tilting amount of the operation lever 43 is applied to the pilot port 25a of the right travel operation valve 25.

  The pilot pressure PRtr is detected by the hydraulic pressure sensor 9, and the right traveling pilot pressure PRcr indicating the right traveling amount is input to the controller 6. Similarly, a pilot pressure (PPC pressure) PRtl corresponding to the tilting amount of the operation lever 44 is applied to the pilot port 26 a of the left travel operation valve 26. The pilot pressure PRtl is detected by the oil pressure sensor 8, and the left traveling pilot pressure PRcl indicating the left traveling amount is input to the controller 6.

  Each of the operation valves 21 to 26 is a flow direction control valve, moves the spool in a direction corresponding to the operation direction of the corresponding operation lever 41 to 44, and oils by an opening area corresponding to the operation amount of the operation lever 41 to 44. Move the spool so that the path opens.

  The pump control valve 5 is operated by a control current pc-epc output from the controller 6 and changes the pump control valve 5 via a servo piston.

The pump control valve 5 prevents the product of the discharge pressure PRp (kg / cm ² ) of the hydraulic pump 3 and the capacity q (cc / rev) of the hydraulic pump 3 from exceeding the pump absorption torque Tpcom corresponding to the control current pc-epc. In addition, the tilt angle of the swash plate of the hydraulic pump 3 is controlled. This control is called PC control.

  The controller 6 outputs a rotation command value to the engine controller 4 including the governor, and increases or decreases the fuel injection amount so as to obtain the target rotation speed according to the current load of the hydraulic pump 3. The rotation speed n and torque T are adjusted.

  Next, control processing by the controller 6 will be described. FIG. 2 is a diagram showing a control flow by the controller 6. FIG. 3 is a diagram showing a processing flow of the target flow rate calculation unit shown in FIG. FIG. 4 is a flowchart showing processing of the engine target rotational speed addition value calculation unit shown in FIG. FIG. 5 is a diagram showing an example of processing of the target rotation speed addition value calculation unit shown in FIG. Further, FIG. 6 is a diagram showing a processing flow of the pump output restriction calculation unit shown in FIG.

  First, as shown in FIGS. 2 and 3, in the target flow rate calculation unit 50, the boom lever signal Lbo, the arm lever signal Lar, the bucket lever signal Lbk, the turning lever signal Lsw, the right traveling pilot pressure PRcr, and the left traveling pilot pressure PRcl. Is input, based on these values, the target flow rate Qbo of the corresponding boom cylinder 31, the target flow rate Qar of the arm cylinder 32, the target flow rate Qbk of the bucket cylinder 33, the target flow rate Qsw of the swing motor 34, and the travel for right travel The target flow rate Qcr of the motor 35 and the target flow rate Qcl for each left travel traveling motor 36 are calculated.

  In the storage device in the controller 6, functional relationships 51a, 52a, 53a, 54a, 55a, and 56a between the operation amount and the target flow rate are stored in a data table format for each hydraulic actuator.

  The boom target flow rate calculation unit 51 calculates the boom target flow rate Qbo corresponding to the current operation amount in the boom raising direction or the operation amount Lbo in the boom lowering direction according to the functional relationship 51a.

  The arm target flow rate calculation unit 52 calculates the arm target flow rate Qa corresponding to the current operation amount in the arm excavation direction or the operation amount La in the arm dump direction according to the functional relationship 52a.

  The bucket target flow rate calculation unit 53 calculates a bucket target flow rate Qbk corresponding to the current operation amount in the bucket excavation direction or the operation amount Lbk in the bucket dump direction according to the functional relationship 53a.

  The turning target flow rate calculation unit 54 calculates a turning target flow rate Qsw corresponding to the current operation amount in the right turn direction or the operation amount Lsw in the left turn direction according to the functional relationship 54a.

  The right travel target flow rate calculation unit 55 calculates the right travel target flow rate Qcr corresponding to the current right travel pilot pressure PRcr according to the functional relationship 55a.

  The left travel target flow rate calculation unit 56 calculates the left travel target flow rate Qcl corresponding to the current left travel pilot pressure PRcl according to the functional relationship 56a.

  For calculation processing, the boom up operation amount, arm excavation operation amount, bucket excavation operation amount, and right turn operation amount are treated as plus sign operation amounts, boom lowering operation amount, arm dump operation amount, bucket dump operation amount. The left turn operation amount is treated as a minus sign operation amount.

  The pump target discharge flow rate calculation unit 60 uses the sum of the hydraulic actuator target flow rates Qbo, Qar, Qbk, Qsw, Qcr, Qcl calculated by the hydraulic actuator target flow rate calculation unit 50 as the pump target discharge flow rate Qsum as follows. Execute the requested process.

Qsum = Qbo + Qar + Qbk + Qsw + Qcr + Qcl (2)
Here, the sum of the target flow rates of the hydraulic actuators is used as the pump target discharge flow rate. The maximum target flow rate among the hydraulic actuator target flow rates Qbo, Qar, Qbk, Qsw, Qcr, Qcl is set as the target of the hydraulic pump 3. The discharge flow rate may be used.

  The first engine target speed calculator 61 calculates a first engine target speed ncom1 corresponding to the pump target discharge flow rate Qsum calculated and output by the target flow rate calculator 50. Here, in the storage device of the controller 6, a functional relationship 61a in which the first engine target rotational speed ncom1 increases as the pump target discharge flow rate Qsum increases is stored in a data table format. As shown below, the first engine target speed ncom1 is the minimum engine that can discharge the pump target discharge flow rate Qsum when the hydraulic pump 3 is operated at the maximum capacity qmax, with the conversion constant α. It is given as the number of revolutions.

ncom1 = Qsum / qmax · α (3)
In the first engine speed calculation unit 61, the first engine target speed ncom1 corresponding to the current pump target discharge flow rate Qsum is calculated according to the functional relationship 61a, that is, the above equation (3).

  The determination unit 62 of the controller 6 determines whether or not the current pump target discharge flow rate Qsum is larger than a predetermined flow rate Qmin. Here, the predetermined flow rate serving as the threshold is set to a flow rate for determining whether or not each of the operation levers 41 to 44 has been operated from the neutral position.

  In the third engine target speed setting unit 68 in the controller 6, as a result of the determination by the determination unit 62, if the current pump target discharge flow rate Qsum is equal to or lower than the predetermined flow rate Qmin, that is, the determination result is NO, The engine target speed ncom3 of 3 is set to a speed nJ near the low idle speed nL of the engine 2. On the other hand, when the current pump target discharge flow rate Qsum is larger than the predetermined flow rate Qmin, that is, when the determination result is YES, the third engine target rotational speed ncom3 is larger than the low idle rotational speed nL of the engine 2. Is set to a large rotational speed nM.

  On the other hand, the engine controller 4 to the controller 6 are input with the current engine speed Ne of the engine 2 and the engine torque Te of the engine 2 estimated from the fuel injection amount. The filter 101 in the controller 6 is a filter having a time constant T1, and outputs an engine torque Te_f obtained by filtering the value of the input engine torque Te. The engine output calculation unit 102 in the controller 6 multiplies the engine speed Ne input from the engine controller 4 by the engine torque Te_f output from the filter 101, and further multiplies the conversion constant Const by the engine output (horsepower) Pe. Is calculated.

  A target engine output calculation unit 103 in the controller 6 calculates a target engine output (horsepower) Pe_aim for a second engine target rotation speed ncom2 to which an engine target rotation speed addition value ncom_add described later is added based on the functional relationship 103a. To do. Note that the initial value of the second engine target speed ncom2 is the first engine target speed ncom1. Here, the function relationship 103a is stored in the storage device in the controller 6, and the target engine output calculation unit 103 outputs the target engine output Pe_aim using the function relationship 103a.

  Here, the functional relationship 103a is the same as the target engine operating line L0 shown in FIG. 27, from the target horsepower line obtained by multiplying the target torque line L1 shown in FIG. , Lowered load sensing boundary.

  The engine target rotational speed addition value calculation unit 104 in the controller 6 outputs the engine target rotational speed addition value ncom_add according to the flowchart shown in FIG. In FIG. 4, the engine target rotational speed addition value calculation unit 104 first sets ncom_add “0” as an initial value (step S101). Thereafter, the engine output Pe is acquired from the engine output calculation unit 102, and the target engine output Pe_aim is acquired from the target engine output calculation unit 103 (step S102). Here, the target engine output calculation unit 103 outputs the target engine output Pe_aim using the first engine target speed ncom1 as an initial value, and in subsequent calculations, the second engine target speed ncom2 is sequentially used. The target engine output Pe_aim is output.

Further, the engine target rotational speed addition value calculation unit 104 calculates a value Iadd obtained by multiplying the value obtained by subtracting the target engine output Pe_aim from the engine output Pe by the conversion coefficient Ie (step S203). This value Iadd is a value converted into the engine speed.

  Thereafter, the engine target rotational speed addition value calculation unit 104 is in a state in which the value of the pump discharge flow rate target value Qsum output from the target flow rate calculation unit 50 is changing in the increasing direction or the value is fixed after the increase. Whether or not (step S104). If the value of the pump discharge flow rate target value Qsum changes in the increasing direction or is not fixed after the increase (No in step S104), a process of adding the value Iadd to the engine target rotational speed addition value ncom_add is performed ( Step S106).

  On the other hand, when the value of the pump discharge flow rate target value Qsum changes in the increasing direction or is fixed after being increased (step S104, Yes), it is further determined whether or not the value Iadd is negative. (Step S105). When the value Iadd is not negative (No at Step S105), the process proceeds to Step S106, and processing for adding the value Iadd to the engine target rotational speed addition value ncom_add is performed. On the other hand, if the value Iadd is negative (step S105, Yes), the process proceeds to step S107 without performing the addition process of the value Iadd.

  That is, in the processing of steps S104 to S106, the pump discharge flow rate target value Qsum output by the target flow rate calculation unit 50 is changing in the increasing direction, or the value is fixed after the increase. If the value Iadd is negative, the process of adding the value Iadd to the engine target rotational speed addition value ncom_add is not performed. Specifically, as shown in FIG. 5, when the increase ΔQsum of the pump discharge flow rate target value Qsum is 0 or more, even if the value Iadd becomes negative, the engine target rotation speed addition value ncom_add is changed to the value Iadd. The process of maintaining the current second engine target speed ncom2 is performed without performing the process of reducing the absolute value. If the pump discharge flow rate target value Qsum is 0 or more, even if the value Iadd becomes negative, control is performed so as not to decrease the target engine speed until the operator intends to reduce power by operating the lever. This is to stabilize the system.

  Thereafter, it is determined whether or not the engine target rotational speed addition value ncom_add is positive (step S107). If the engine target rotational speed addition value ncom_add is positive (step S107, Yes), it is further determined whether or not all lever inputs (lever potentiometer signals) are in the neutral state or in the vicinity thereof (step S108). If all lever inputs are not in the neutral state or the vicinity thereof (step S108, No), it is further determined whether or not an assist flag assist_flag described later is true (step S109).

  If the engine target rotational speed addition value ncom_add is positive (Yes at Step S107), all lever inputs are not in the neutral state or its vicinity (No at Step S108), and the assist flag assist_flag is not True (Step S109). , No), a process of adding the engine target rotational speed addition value ncom_add to the first engine target rotational speed ncom1 is performed (step S110), and the second engine target rotational speed ncom2 (corresponding to the corrected engine target rotational speed). Is generated, the process proceeds to step S102, and the above-described processing is repeated.

  On the other hand, when the engine target rotational speed addition value ncom_add is not positive (step S107, No), when all lever inputs are in the neutral state or in the vicinity thereof (step S108, Yes), or when the assist flag assist_flag is True (step) In S109, Yes), without adding the engine target rotational speed addition value ncom_add to the first engine target rotational speed ncom1, the current first engine target rotational speed ncom1 is directly used as the second engine target rotational speed. Is output as a number (corresponding to the corrected engine target speed), the process proceeds to step S102, and the above-described processing is repeated.

  This is because if the engine target rotational speed addition value ncom_add is not positive, it means that the load sensing boundary line is not approached and the load is not large, and it is not necessary to increase the engine rotational speed. In addition, when all lever inputs are in the neutral state or in the vicinity thereof, the operator's intention is given priority. Further, when the assist flag assist_flag is True, it is assisted by the electric motor without increasing the engine speed.

  The engine target rotational speed addition value ncom_add output in this way is added to the first engine target rotational speed ncom1 by the adding unit 105, and is output as the second engine target rotational speed ncom2. The second engine target speed ncom2 is output to the target engine output calculation unit 103 via the branching unit 106.

  The maximum value selection unit 64 in the controller 6 selects the higher engine target speed ncom23, which is the higher one of the second engine target speed ncom2 and the third engine target speed ncom3.

  On the other hand, the pump output restriction calculation unit 70 performs processing according to the flow shown in FIG. In the following, the determination result TRUE is abbreviated as T, and the determination result FALSE is abbreviated as F.

  It is determined that the work pattern of the plurality of hydraulic actuators 21 to 26 is the operation pattern (1) “traveling operation”, and the output limit value Pplimit of the hydraulic pump 3 is adapted to the work pattern “traveling operation”. Is set to Pplimit1.

  The pump output limit calculation unit 70 calculates the output (horsepower) limit value Pplimit of the hydraulic pump 3 according to the work pattern of the plurality of hydraulic actuators 21 to 26.

  As output limit values of the hydraulic pump 3, Pplimit1, Pplimit3, Pplimit4, Pplimit5, and Pplimit6 are calculated in advance. The size of the output limit value of the hydraulic pump 3 is set so as to decrease sequentially in the order of Pplimit1, Pplimit2, Pplimit3, Pplimit4, Pplimit5, and Pplimit6, as shown on the torque diagram shown in FIG. And

  That is, when the right traveling pilot pressure Prcr is larger than the predetermined pressure Kc or when the left traveling pilot pressure Prcl is larger than the predetermined pressure Kc (determination T in step 71), the plurality of hydraulic actuators 21 to 26 are operated. It is determined that the work pattern is the work pattern (1) “traveling operation”, and the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit1 so as to match the work pattern “traveling operation”.

  In the same manner, the following determinations are made in steps 72 to 79. That is, in step 72, it is determined whether or not the right turn operation amount Lsw is larger than the predetermined operation amount Ksw and the left turn operation amount Lsw is smaller than the predetermined operation amount −Ksw.

  In step 73, it is determined whether or not the boom lowering operation amount Lbo is smaller than a predetermined operation amount -Kbo.

  In step 74, whether or not the boom raising operation amount Lbo is larger than a predetermined operation amount Kbo, whether the arm excavation operation amount La is larger than the predetermined operation amount Ka, or whether the arm dump operation amount La is Whether or not the predetermined operation amount −Ka is smaller than that, or whether or not the bucket excavation operation amount Lbk is larger than the predetermined operation amount Kbk, or the bucket dump operation amount Lbk is smaller than the predetermined operation amount −Kbk. It is determined whether or not.

  In step 75, it is determined whether or not the arm excavation operation amount La is larger than a predetermined operation amount Ka.

  In step 76, it is determined whether or not the bucket excavation operation amount Lbk is larger than a predetermined operation amount Kbk.

  In step 77, it is determined whether or not the discharge pressure PRp of the hydraulic pump 3 is smaller than a predetermined pressure Kp1.

  In step 78, it is determined whether or not the arm dump operation amount La is smaller than a predetermined operation amount -Ka.

  In step 79, it is determined whether or not the bucket dump operation amount Lbk is smaller than a predetermined operation amount -Kbk.

  In step 80, it is determined whether or not the discharge pressure PRp of the hydraulic pump 3 is greater than a predetermined pressure Kp2.

  In step 81, it is determined whether or not the discharge pressure PRp of the hydraulic pump 3 is greater than a predetermined pressure Kp3.

  When the determination at step 71 is F, the determination at step 72 is T, and the determination at step 73 is T, the operation pattern of the hydraulic actuators 21 to 26 is an operation pattern of “turning operation and boom lowering operation” ( 2), the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit6 so as to conform to the work pattern.

  When the judgment of step 71 is F, the judgment of step 72 is T, the judgment of step 73 is F, and the judgment of step 74 is T, the work pattern of the hydraulic actuators 21 to 26 is “turn operation and boom”. It is determined that the work pattern (3) is “work machine operation other than lowering”, and the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit1 so as to match the work pattern.

  When the judgment at step 71 is F, the judgment at step 72 is T, the judgment at step 73 is F, and the judgment at step 74 is F, the work pattern of the plurality of hydraulic actuators 21 to 26 is “single operation of turning operation”. It is determined that the operation pattern is “operation” (4), and the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit6 so as to match the operation pattern.

  When the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is T, the judgment of step 76 is T, and the judgment of step 77 is T, the work patterns of the plurality of hydraulic actuators 21 to 26 Is determined to be a work pattern (5) of “when the load is small (for example, work for holding earth and sand) by arm excavation operation and bucket excavation operation”, and the output limit of the hydraulic pump 3 is limited so as to conform to the work pattern. The value Pplimit is set to Pplimit2.

  When the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is T, the judgment of step 76 is T, and the judgment of step 77 is F, the work patterns of the plurality of hydraulic actuators 21 to 26 Is determined to be the work pattern (6) “when the load is large in the arm excavation operation and the bucket excavation operation (for example, excavation work by simultaneous operation of the arm and bucket)”, and the hydraulic pressure is adjusted so as to conform to the work pattern The output limit value Pplimit of the pump 3 is set to Pplimit1.

  When the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is T, and the judgment of step 76 is F, the work pattern of the plurality of hydraulic actuators 21 to 26 is “arm excavation operation”. The output limit value Pplimit of the hydraulic pump 3 is set to Pplimit1 so as to match the work pattern (7).

  If the determination in step 71 is F, the determination in step 72 is F, the determination in step 75 is F, the determination in step 78 is T, the determination in step 79 is T, and the determination in step 80 is T, a plurality of hydraulic pressures The work pattern of the actuators 21 to 26 is determined to be a work pattern (8) of “when the load is large in the arm earthing operation and the bucket earthing operation (for example, earth and sand pushing work by simultaneous earth and bucket earthing operation)”. Then, the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit3 so as to conform to the work pattern.

  If the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is F, the judgment of step 78 is T, the judgment of step 79 is T, and the judgment of step 80 is F, a plurality of hydraulic pressures The work pattern of the actuators 21 to 26 is determined to be a work pattern (9) of “when the load is small in the arm earthing operation and the bucket earthing operation (for example, the work for returning the arm and the bucket simultaneously in the air)” The output limit value Pplimit of the hydraulic pump 3 is set to Pplimit5 so as to conform to the work pattern.

  If the determination in step 71 is F, the determination in step 72 is F, the determination in step 75 is F, the determination in step 78 is T, the determination in step 79 is F and the determination in step 81 is T, a plurality of hydraulic actuators The work patterns 21 to 26 are determined to be work patterns (10) of “when the load is large due to the single arm earth removal operation (for example, earth and sand pushing work by the arm earth removal work)”, and are adapted to the work pattern. In addition, the output limit value Pplimit of the hydraulic pump 3 is set to Pplimit3.

  If the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is F, the judgment of step 78 is T, the judgment F of step 79 is F and the judgment of step 81 is F, a plurality of hydraulic actuators The work patterns 21 to 26 are determined to be the work pattern (11) “when the load is small (for example, work to return the arm in the air) by the arm single earth removal operation”, and so as to conform to the work pattern. The output limit value Pplimit of the hydraulic pump 3 is set to Pplimit5.

  When the judgment of step 71 is F, the judgment of step 72 is F, the judgment of step 75 is F, and the judgment of step 78 is F, the work pattern of the plurality of hydraulic actuators 21 to 26 is “other work”. The output limit value Pplimit of the hydraulic pump 3 is set to Pplimit1 so as to match the work pattern (12).

  Next, the fourth engine target speed calculator 63 in the controller 6 is a fourth engine target speed corresponding to the output (horsepower) limit value Pplimit of the hydraulic pump 3 calculated by the pump output limit calculator 70. Calculate ncom4.

  The storage device in the controller 6 stores a functional relationship 63a in the form of a data table in which the fourth engine target speed ncom4 increases as the output limit value Pplimit of the hydraulic pump 3 increases.

  In the fourth engine speed calculation unit 63, the current working pattern of the plurality of hydraulic actuators 21 to 26, that is, the fourth engine target speed ncom4 corresponding to the output limit value Pplimit of the hydraulic pump 3 is determined according to the function relation 63a. Calculated.

  The minimum value selection unit 65 selects the engine target speed ncom which is lower of the engine target speed ncom23 selected by the maximum value selection part 64 and the fourth engine target speed ncom4.

  The controller 6 outputs a rotation command value for setting the engine speed n to the target speed ncom to the engine controller 4, and the controller 4 outputs the engine target speed ncom on the target torque line L1 shown in FIG. The fuel injection amount is increased or decreased so that

  The pump absorption torque calculation unit 66 calculates the target absorption torque Tpcom of the hydraulic pump 3 corresponding to the engine target rotation speed ncom.

  In the storage device in the controller 6, a functional relationship 66a in which the target absorption torque Tpcom of the hydraulic pump 3 increases as the engine target speed ncom increases is stored in a data table format. This function 66a is a curve corresponding to the target torque line L1 on the torque diagram shown in FIG.

  FIG. 7 shows a torque diagram of the engine 2 as in FIG. 27, where the horizontal axis represents the engine speed n (rpm; rev / min) and the vertical axis represents the torque T (N · m). Yes. The function 66a corresponds to the target torque line L1 on the torque diagram shown in FIG.

  In the pump absorption torque calculation unit 66, the target absorption torque Tpcom of the hydraulic pump 3 corresponding to the current engine target speed ncom is calculated according to the function 66a.

  In the control current calculator 67, a control current pc-epc corresponding to the pump target absorption torque Tpcom is calculated.

  In the storage device in the controller 6, a functional relationship 67a in which the control current pc-epc increases with an increase in the pump target absorption torque Tpcom is stored in a data table format.

  In the pump absorption torque calculation unit 66, the control current pc-epc corresponding to the current pump target absorption torque Tpcom is calculated according to the functional relationship 67a.

  A control current pc-epc is output from the controller 6 to the pump control valve 5 to change the pump control valve 5 via the servo piston. The pump control valve 5 prevents the product of the discharge pressure PRp (kg / cm 2) of the hydraulic pump 3 and the capacity q (cc / rev) of the hydraulic pump 3 from exceeding the pump absorption torque Tpcom corresponding to the control current pc-epc. The tilt angle of the swash plate of the hydraulic pump 3 is PC-controlled.

  Here, as shown in FIG. 7, when the engine 2 and the hydraulic pump 3 are controlled according to the target torque line L1 in which the pump absorption torque Tpcom decreases as the engine speed n decreases, the fuel efficiency, engine efficiency, and pump efficiency are improved. However, there is a problem that the responsiveness of the engine 2 is poor, although effects such as reduction of noise and prevention of engine stall are obtained. For example, even if the operation lever 41 is tilted from the neutral position to start excavation work and the engine 2 is raised from a low speed, the load of the hydraulic pump 3 suddenly increases at the initial stage (transient state) when the lever is started to fall. Therefore, the engine output has no margin for the power of the pump absorption horsepower, and the power for accelerating the engine 2 is insufficient. For this reason, the engine 2 may not be raised to the target rotational speed or may be raised only very slowly.

  In this regard, in the first embodiment, the second engine target speed ncom2 obtained by adding the engine target speed addition value ncom_add to the first engine target speed ncom1 that matches the current pump target discharge flow rate Qsum is set. On the other hand, when it is determined that the current pump target discharge flow rate Qsum is larger than the predetermined flow rate Qmin, the rotation speed nM larger than the engine low idle rotation speed nL is set as the third engine target rotation speed ncom3. Is set. If the third engine target speed ncom3 is equal to or higher than the second engine target speed ncom2, the engine speed is controlled so that the third engine target speed ncom3 is obtained. Further, the hydraulic pump 3 is controlled so that a pump absorption torque corresponding to the third engine target speed ncom3 is obtained.

  For this reason, for example, when the operation lever 41 is tilted from the neutral position in order to start excavation work, the engine speed increases in advance and the engine torque increases before the load of the hydraulic pump 3 suddenly increases. There is a margin in power for accelerating 2. For this reason, the engine 2 can be rapidly raised from the low speed range to the target speed, and the response of the engine 2 is improved.

  In the first embodiment, the engine target revolution speed addition value calculation unit 104 adds the engine target revolution speed addition value ncom_add to the first engine target revolution speed ncom1. When the current engine output Pe is larger than the target engine output Pe_aim corresponding to the second engine target speed ncom2, the engine target speed addition value calculation unit 104 determines the engine target speed according to the difference. The engine speed is increased by adding the number addition value ncom_add to the first engine target speed ncom1.

With reference to FIG. 7 and FIG. 8, the engine speed increasing process by the engine target speed addition value calculation unit 104 will be described. For convenience of explanation, description will be made using a torque diagram instead of horsepower. FIG. 7 is a torque diagram showing changes in engine torque with respect to engine speed. This torque diagram is the same as the torque diagram shown in FIG. 27, and the target engine operation line L0 corresponds to the target torque line L1. The load sensing torque boundary line L2 is a line that is lower than the target torque line L1 by a predetermined torque. A line obtained by multiplying the load sensing torque boundary line L1 by the engine speed becomes a load sensing boundary line, and the function relationship 103a of the target engine output calculation unit 103 is Become. The load sensing torque boundary line L2 indicates that a region surrounded by the target torque line L1 and the load sensing torque line L2 is a load sensing region E and is a boundary of the load sensing region E. That is, the load sensing area E is defined as an area that is close to the target torque line L1 to some extent. If the load sensing area E enters the load sensing area E, it is considered that the construction machine is requesting output and the engine speed is increased. I try to speed up.

  FIG. 8 is a diagram showing temporal changes in engine speed and torque when there is a lever input. 7 and 8, the state “1” is an idle state, and the engine speed is GOV_1. When lever input starts at time T1, the engine speed increases in accordance with the lever operation and becomes the state “2”. At time T2 when the lever is fixed, the engine speed becomes GOV_2. In this state “2”, the torque gradually increases as time passes, and at the time T3 at the end of the state “2”, the engine speed and the torque exceed the load sensing torque boundary line L2. That is, the engine speed is equal to or less than the engine speed of the load sensing torque boundary line L2, and the torque is equal to or greater than the torque of the load sensing torque boundary line L2. The state of entering the load sensing region E beyond the load sensing torque boundary line L2 is the state “3”, and in this state “3”, the engine target revolution speed addition value calculation unit 104 performs the engine target revolution speed operation. The added value ncom_add is added to the first engine target speed ncom1 to increase the speed. As a result, in the second half of the state “3”, the engine speed is increased and the torque is also decreased. At the time T4 at the end of the state “3”, the engine speed and the torque are set at the load sensing torque boundary line L2. The engine speed increase process by the engine target rotation speed addition value calculation unit 104 is not performed.

  As described above, in the first embodiment, when the engine speed and the torque state enter the load sensing region E, the engine speed is increased assuming that an increase in output is required. In particular, since the engine speed is automatically increased to increase the output without performing the lever operation again for the load applied after the lever operation, the operability for the operator can be improved. That is, the output is automatically increased when a large load is applied.

  In the first embodiment, the second engine target speed ncom2 is set by adding the engine target speed addition value ncom_add to the first engine target speed ncom1 that matches the current pump target discharge flow rate Qsum. On the other hand, the output limit value Pplimit of the hydraulic pump 3 is set according to the work pattern of the plurality of hydraulic actuators 21 to 26, and the fourth engine target speed ncom4 corresponding to this is set. If the fourth engine target speed ncom4 is equal to or lower than the engine target speed ncom23, the engine speed is controlled so that the fourth engine target speed ncom4 is obtained, and the pump corresponding to the fourth engine target speed ncom4 is obtained. The hydraulic pump 3 is controlled so that the absorption torque can be obtained. For this reason, the pump absorption torque can be set to an appropriate value, and unnecessary energy consumption can be suppressed.

  In the first embodiment described above, the determination that the operation means 41 to 44 is switched from the non-operation state to the operation state is not limited to this, and the operation amount of the operation means 41 to 44 is predetermined. If the threshold value is larger than the threshold value, it may be determined that the operating means 41 to 44 are switched from the non-operating state to the operating state.

  The method for setting the first target engine speed is arbitrary. For example, as described in the prior art, the rotation speed of the engine 2 is set by the fuel dial, and the first target engine rotation speed ncom1 of the engine 2 is set according to the setting value of the fuel dial. it can.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. The construction machine 201 according to the second embodiment of the present invention is based on the construction machine 1 shown in FIG. 1, and the PTO shaft 10, the generator motor 11, the battery 12, the inverter 13, the construction machine 1 shown in FIG. A rotation sensor 14 and a voltage sensor 15 are added, and an electric action and a power generation action by the generator motor 11 are performed.

  That is, as shown in FIG. 10, the output shaft of the engine 2 is connected to the drive shaft of the hydraulic pump 3 and the drive shaft of the generator motor 11 via the PTO shaft 10. The generator motor 11 performs a power generation operation and an electric operation. That is, the generator motor 11 operates as an electric motor (motor) and also operates as a generator. The generator motor 11 also functions as a starter that starts the engine 2. When the starter switch is turned on, the generator motor 11 is electrically operated to rotate the output shaft of the engine 2 at a low speed (for example, 400 to 500 rpm) to start the engine 2.

  The generator motor 11 is torque-controlled by an inverter 13. As will be described later, the inverter 13 controls the torque of the generator motor 11 according to the generator motor command value GEN_com output from the controller 6.

  The inverter 13 is electrically connected to the battery 12 via a DC power line. The controller 6 operates using the battery 12 as a power source.

  The battery 12 is configured by a capacitor, a storage battery, or the like, and stores (charges) the power generated when the generator motor 11 generates power. In addition, the battery 12 supplies the electric power stored in the battery 12 to the inverter 13. In this specification, a capacitor that accumulates electric power as static electricity and a storage battery such as a lead battery, a nickel metal hydride battery, or a lithium ion battery are also referred to as a “capacitor”.

  The generator motor 11 is provided with a rotation sensor 14 that detects the current actual rotational speed GEN_spd (rpm) of the generator motor 11, that is, the actual rotational speed of the engine 2. A signal indicating the actual rotation speed GEN_spd detected by the rotation sensor 14 is input to the controller 6.

  In addition, the livestock battery 12 is provided with a voltage sensor 15 that detects the voltage BATT_volt of the livestock battery 12. A signal indicating the voltage BATT_volt detected by the voltage sensor 15 is input to the controller 6.

  In addition, the controller 6 outputs the generator motor command value GEN_com to the inverter 13 to cause the generator motor 11 to perform a power generation operation or an electric operation. When a command value GEN_com for operating the generator motor 11 as a generator is output from the controller 6 to the inverter 13, a part of the output torque generated by the engine 2 is generated via the engine output shaft. Is generated by absorbing the torque of the engine 2. The AC power generated by the generator motor 11 is converted into DC power by the inverter 13 and is stored (charged) in the battery 12 via the DC power line.

  Further, when a command value GEN_com for operating the generator motor 11 as an electric motor is output from the controller 6 to the inverter 13, the inverter 13 controls the generator motor 11 to operate as an electric motor. That is, electric power is output (discharged) from the battery 12 and the DC power stored in the battery 12 is converted into AC power by the inverter 13 and supplied to the generator motor 11 to rotate the drive shaft of the generator motor 11. As a result, torque is generated in the generator motor 11, and this torque is transmitted to the engine output shaft via the drive shaft of the generator motor 11 and added to the output torque of the engine 2 (the output of the engine 2 is assisted). ). This added output torque is absorbed by the hydraulic pump 3.

  The power generation amount (absorption torque amount) and the motor drive amount (assist amount; generated torque amount) of the generator motor 11 change according to the contents of the generator motor command value GENcom.

  Here, the control process by the controller 6 of the construction machine 201 will be described with reference to FIGS.

  The process shown in FIG. 11 is the same as the process shown in FIG. 2. When the engine target speed ncom is selected by the minimum value selection unit 65, the control flow shown in FIG. Then, the control process shown in FIG. 12 is performed.

  In the following, calculation processing is performed after converting the engine speed and the engine target speed to the generator motor speed and the generator motor target speed, respectively. However, in the following explanation, the generator motor speed and power generation It is also possible to perform the same calculation process by replacing the motor target rotational speed with the engine rotational speed and the engine target rotational speed, respectively.

  In the generator motor target rotational speed calculation unit 96, the target rotational speed Ngen_com of the generator motor 11 corresponding to the current engine target rotational speed ncom is calculated by the following equation.

Ngen_com = ncom × K2 (4)
Here, K2 is a reduction ratio of the PTO shaft 10.

  In the assist presence / absence determination unit 90, the target rotation speed Ngen_com of the generator motor 11, the current actual rotation speed GEN_spd of the generator motor 11 detected by the rotation sensor 14, and the current voltage BATT_volt of the livestock generator 12 detected by the voltage sensor 15. Based on the above, it is determined whether or not the generator motor 11 assists the engine 2 (assist presence / absence).

  As shown in FIG. 13, in the assist presence / absence determination unit 90, first, a deviation calculation unit 91 calculates a deviation Δgen_spd between the generator motor target rotation speed Ngen_com and the generator motor actual rotation speed GEN_spd.

  Next, in the first determination unit 92, when the deviation Δgen_spd between the generator motor target rotation speed Ngen_com and the generator motor actual rotation speed GEN_spd is equal to or greater than the first threshold value ΔGC1, the generator motor 11 is electrically operated. When the assist flag assist_flag is set to T and the deviation Δgen_spd between the generator motor target speed Ngen_com and the generator motor actual speed GEN_spd is equal to or smaller than the second threshold value ΔGC2 smaller than the first threshold value ΔGC1 Then, it is determined that the generator motor 11 is not electrically operated (however, if necessary, the power is generated and the electric power is stored in the battery 12), and the assist flag is set to F.

  Further, when the deviation Δgen_spd between the generator motor target rotation speed Ngen_com and the generator motor actual rotation speed GEN_spd is equal to or less than the third threshold value ΔGC3, it is determined that the generator motor 11 generates power, and the assist flag assist_flag is set to T. When the deviation Δgen_spd between the generator motor target rotation speed Ngen_com and the generator motor actual rotation speed GEN_spd is equal to or larger than a fourth threshold value ΔGC4 that is larger than the third threshold value ΔGC3, the generator motor 11 is not generated. (However, it is determined that the electric power is generated as necessary and the electric power is stored in the battery 12), and the assist flag is set to F.

  As described above, when the rotational speed deviation Δgen_spd is a plus sign and becomes larger than a certain level, the generator motor 11 is electrically operated to assist the engine 2 because the current engine rotational speed and the target rotational speed are separated. This is to quickly increase the engine speed toward the target engine speed.

  Further, when the rotational speed deviation Δgen_spd is a sign minus and increases to a certain degree or more, the generator motor 11 is caused to generate power and the engine 2 is reversely assisted. This is because the energy of the engine 2 is regenerated.

  Further, by providing hysteresis between the first threshold value ΔGC1 and the second threshold value ΔGC2, and by providing hysteresis between the third threshold value ΔGC3 and the fourth threshold value ΔGC4, Control hunting is prevented.

  In the second determination unit 93, when the voltage BATT_volt of the battery 12 is within the predetermined range BC1 to BC4 (BC2 to BC3), the assist flag assist_flag is set to T, and when the voltage is outside the predetermined range, Set assist flag assist_flag to F.

  The first threshold value BC1, the second threshold value BC2, the third threshold value BC3, and the fourth threshold value BC4 are set to the voltage value BATT_volt. It is assumed that the first threshold value BC1, the second threshold value BC2, the third threshold value BC3, and the fourth threshold value BC4 increase in this order.

  When the voltage value BATT_volt of the battery 12 becomes equal to or lower than the third threshold value BC3, the assist flag assist_flag is set to T, and when the voltage value BATT_volt of the battery 12 becomes equal to or higher than the fourth threshold value BC4, the assist flag assist_flag is set to F. When the voltage value BATT_volt of the battery 12 becomes equal to or higher than the second threshold value BC2, the assist flag assist_flag is set to T, and when the voltage value BATT_volt of the battery 12 becomes equal to or lower than the first threshold value BC1, the assist flag assist_flag is set to F. .

  As described above, only when the voltage BATT_volt of the battery 12 is within the predetermined range BC1 to BC4 (BC2 to BC3), the assist is made when the voltage is low or high outside the predetermined range. This is to avoid adverse effects such as overcharge and complete discharge applied to the battery 12 by preventing the assist.

  Further, by providing a hysteresis between the first threshold value BC1 and the second threshold value BC2, and providing a hysteresis between the third threshold value BC3 and the fourth threshold value BC4, Control hunting is prevented.

  In the AND circuit 94, when the assist flag assist_flag obtained by the first determination unit 92 and the assist flag assist_flag obtained by the second determination unit 93 are both T, the content of the assist flag assist_flag is finally set to T Otherwise, the content of the assist flag assist_flag is finally set to F.

  The assist flag assist_flag output from the assist presence / absence determination unit 90 is output to the engine target rotation speed addition value calculation unit 104. When the assist flag assist_flag is True, the engine target rotation speed addition value calculation unit 104 An additional output of the rotational speed addition value ncom_add is not performed.

  The assist flag determination unit 95 determines whether or not the content of the assist flag assist_flag output from the assist presence determination unit 90 is T.

  In the generator motor command value switching unit 87, the content of the generator motor command value GEN_com to be given to the inverter 13 is set to the target rotational speed, depending on whether or not the determination result of the assist flag determination unit 95 is T (F). Switch to target torque.

  The generator motor 11 is controlled by rotation speed control or torque control via the inverter 13.

  Here, the rotation speed control is control for adjusting the rotation speed of the generator motor 11 so that the target rotation speed can be obtained by giving the target rotation speed as the generator motor command value GEN_com. The torque control is control for adjusting the torque of the generator motor 11 so that the target torque is obtained by giving the target torque as the generator motor command value GEN_com.

  In the modulation processing unit 97, the target rotational speed of the generator motor 11 is calculated and output. The generator motor torque calculation unit 68 calculates and outputs the target torque of the generator motor 11.

  That is, the modulation processing unit 97 outputs the rotation speed Ngen_com that has been subjected to the modulation process according to the characteristic 97 a with respect to the generator motor target rotation speed Ngen_com obtained by the generator motor target rotation speed calculation unit 96. Instead of outputting the generator motor target rotation speed Ngen_com inputted from the generator motor target rotation speed calculation unit 96 as it is, the rotation speed is gradually increased over time t and from the generator motor target rotation speed calculation unit 96. The input generator motor target rotational speed Ngen_com is reached.

  With reference to the torque diagrams shown in FIGS. 14 to 17, effects when the modulation process is performed with respect to the case where the modulation process is not performed will be described.

  FIG. 14 is a diagram for explaining the movement of the governor when there is no modulation processing during engine acceleration, and FIG. 15 is a diagram for explaining the motion of the governor when there is modulation processing during engine acceleration. FIG. 16 is a diagram for explaining the movement of the governor when the modulation process is not performed when the engine is decelerated, and FIG. 17 is a diagram for explaining the movement of the governor when the modulation process is performed when the engine is decelerated. When a mechanical governor is used as the governor, there is a problem that the speed specified by the governor is delayed from the actual engine speed.

  As shown in FIGS. 14 and 15, consider a case where the engine 2 is accelerated from the low rotation matching point P 0 to the high rotation side when the load of the hydraulic pump 3 is large. 14 and 15, P2 corresponds to the engine torque, and the total torque P3 of the engine 2 and the generator motor 11 is obtained by adding the assist torque to the engine torque. P1 corresponds to the pump absorption torque, and the sum of the pump absorption torque and the acceleration torque corresponds to the total torque P3.

  As shown in FIG. 14, when there is no modulation processing, an assist torque is generated according to the deviation between the target engine speed and the actual engine speed. When the deviation is large, the assist torque by the generator motor 11 increases corresponding to the large deviation. For this reason, the engine 2 accelerates faster than the movement of the governor, and the actual rotational speed becomes larger than the rotational speed specified by the governor. When the engine 2 accelerates quickly, the fuel injection amount is reduced by adjusting the governor, and the engine torque is reduced. For this reason, although the engine 2 is assisted by the generator motor 11, the engine 2 becomes friction, and the acceleration of the engine 2 does not increase. For this reason, while reducing the fuel injection amount and reducing the engine torque, the engine 2 is lost and the engine 2 is accelerated, resulting in energy loss and the result that the engine 2 is not sufficiently accelerated.

  On the other hand, as shown in FIG. 15, when the modulation process is performed, the modulation process is performed on the target engine speed, and the deviation between the target engine speed and the actual engine speed becomes small. A small assist torque is generated in the generator motor 11. For this reason, the movement of the governor follows the acceleration of the engine 2, and the rotational speed designated by the governor matches the actual rotational speed. For this reason, energy loss is reduced and the engine 2 is sufficiently accelerated.

  Next, a case where the engine 2 is decelerated will be described. As shown in FIGS. 16 and 17, consider a case where the engine 2 is decelerated from the high rotation matching point P0 to the low rotation side when the load of the hydraulic pump 3 is large.

  16 and 17, P2 corresponds to the engine torque, and the total torque P3 of the engine 2 and the generator motor 11 is obtained by adding the regenerative torque to the engine torque. P1 corresponds to the pump absorption torque, and the sum of the pump absorption torque and the deceleration torque corresponds to the total torque P3.

  As shown in FIG. 16, when there is no modulation process, regenerative torque is generated according to the deviation between the target engine speed and the actual engine speed. When the deviation is large, the regenerative torque by the generator motor 11 is increased corresponding to the large deviation. For this reason, the engine 2 decelerates faster than the movement of the governor, and the actual rotational speed becomes smaller than the rotational speed specified by the governor. When the engine 2 decelerates quickly, the fuel injection amount increases due to the adjustment of the governor, and the engine torque increases. Therefore, the engine 2 decelerates while generating power with the generator motor 11 while increasing the torque. As a result, while the engine 2 increases the torque and the generator motor 11 collects the increased engine energy, the engine 2 is decelerated, and wasteful power generation is performed and fuel is wasted. .

  On the other hand, as shown in FIG. 17, in the case where there is a modulation process, the modulation process is performed on the target engine speed, and the deviation between the target engine speed and the actual engine speed becomes small. A small regenerative torque is generated in the generator motor 11. For this reason, the movement of the governor follows the deceleration of the engine 2, and the rotational speed designated by the governor matches the actual rotational speed. For this reason, the torque of the engine 2 becomes negative, and the engine 2 decelerates while recovering the speed energy of the engine 2 by the generator motor 11. For this reason, the engine 2 can be decelerated efficiently without causing unnecessary energy consumption.

  In the generator motor torque calculation unit 68, the target torque Tgen_com corresponding to the voltage BATT_volt is calculated based on the current voltage BATT_volt of the livestock generator 12 detected by the voltage sensor 15.

  The storage device has a functional relationship 68a with hysteresis that the target torque Tgen_com decreases according to the increase 68b of the voltage BATT_volt of the battery 12 and increases according to the decrease 68c of the voltage BATT_volt of the battery 12. Stored in table format. This functional relationship 68a is set in order to maintain the voltage value of the battery 12 within a desired range by adjusting the power generation amount of the generator motor 11.

  In the generator motor torque calculation unit 68, the target torque Tgencom corresponding to the current voltage BATT_volt of the battery 12 is output according to the functional relationship 68a.

  When the assist flag determination unit 95 determines that the content of the assist flag assert_flag is T, the generator motor command value switching unit 87 is switched to the modulation processing unit 97 side, and the generator motor target output from the modulation processing unit 97 is output. The rotational speed Ngen_com is output to the inverter 13 as a generator motor command value GEN_com, the rotational speed of the generator motor 11 is controlled, and the generator motor 11 performs an electric action or a power generation action.

  When the assist flag determination unit 95 determines that the content of the assist flag assert_flag is F, the generator motor command value switching unit 87 is switched to the generator motor torque calculation unit 68 side, and the generator motor torque calculation unit 68 The output generator motor target torque Tgen_com is output to the inverter 13 as a generator motor command value GEN_com, the torque of the generator motor 11 is controlled, and the generator motor 11 generates power.

  The pump absorption torque command value switching unit 88 determines the content of the pump target absorption torque T to be given to the control current calculation unit 67 according to whether or not the determination result of the assist flag determination unit 95 is T (F). The first pump target absorption torque Tp_com1 is switched to the second pump target absorption torque Tp_com2.

  The first pump target absorption torque Tp_com1 is calculated by the first pump target absorption torque calculation unit 66 (the same configuration as the pump absorption torque calculation unit 66 shown in FIG. 2).

  That is, the first pump target absorption torque Tpcom1 is given as a torque value on the first target torque line L1 in the torque diagram of FIG. The first target torque line L1 is set as a target torque line such that the target absorption torque Tp_com1 of the hydraulic pump 3 decreases as the engine target speed n decreases.

  The second pump target absorption torque Tpcom2 is calculated by the second pump target absorption torque calculation unit 85. That is, the second pump target absorption torque Tp_com2 is on the second target torque line L12 where the pump target absorption torque becomes larger in the low rotation region than the first target torque line L1 in the torque diagram of FIG. It is given as a torque value.

  The first pump target absorption torque calculator 66 calculates the first pump target absorption torque Tpcom1 of the hydraulic pump 3 corresponding to the engine target speed ncom.

  In the storage device, a functional relationship 66a in which the first target absorption torque Tp_com1 of the hydraulic pump 3 increases as the engine target speed ncom increases is stored in a data table format. This function 66a is a curve corresponding to the first target torque line L1 on the torque diagram shown in FIG.

  FIG. 18 shows a torque diagram of the engine 2. The horizontal axis represents the engine speed n (rpm; rev / min), and the vertical axis represents the torque T (N · m). The function 66a corresponds to the target torque line L1 on the torque diagram shown in FIG.

  In the first pump target absorption torque calculating unit 66, the first pump target absorption torque Tp_com1 corresponding to the current engine target rotational speed ncom is calculated according to the functional relationship 66a.

  In the second pump target absorption torque calculation unit 85, the second pump target absorption torque Tp_com2 of the hydraulic pump 3 corresponding to the generator motor rotation speed GEN_spd (engine actual rotation speed) is calculated.

  In the storage device, a functional relationship 85a in which the second target absorption torque Tp_com2 of the hydraulic pump 3 changes according to the generator motor speed GEN_spd (actual engine speed) is stored in a data table format. This function 85a is a curve corresponding to the second target torque line L12 on the torque diagram shown in FIG. 18, and the pump target absorption torque increases in the low rotation region with respect to the first target torque line L1. It has the following characteristics. For example, the second target torque line L12 is a curve corresponding to an equal horsepower line, and the characteristic can be adopted so that the torque decreases as the engine speed increases.

  In the second pump target absorption torque calculating unit 85, the second pump target absorption torque Tp_com2 corresponding to the current generator motor rotation speed GEN_spd (engine actual rotation speed) is calculated according to the functional relationship 85a.

  When the assist flag determination unit 95 determines that the content of the assist flag assist_flag is T, the pump absorption torque command value switching unit 88 is switched to the second pump target absorption torque calculation unit 85 side, and the second pump The second pump target absorption torque Tp_com2 output from the target absorption torque calculation unit 85 is output to the subsequent filter processing unit 89 as the pump target absorption torque Tp_com.

  When the assist flag determination unit 95 determines that the content of the assist flag assist_flag is F, the pump absorption torque command value switching unit 88 is switched to the first pump target absorption torque calculation unit 66 side, and the first The first pump target absorption torque Tp_com1 output from the pump target absorption torque calculator 66 is output to the subsequent filter processing unit 89 as the pump target absorption torque Tp_com.

  As described above, the pump absorption torque command value switching unit 88 switches the selection of the target absorption torques Tp_com1 and Tp_com2 of the hydraulic pump 3, that is, the target torque lines L1 and L12 in FIG.

  In the filter processing unit 89, when the selection of the target torque lines L1 and L12 is switched, the pump target absorption torque (second pump target absorption) on the target torque line before switching (for example, the second target torque line L12) is switched. A filter process for gradually changing from the torque Tp_com2) to the pump target absorption torque (first pump target absorption torque Tp_com1) on the target torque line after switching (first target torque line L1) is performed.

  That is, when the selection of the target torque lines L1 and L12 is switched, the filter processing unit 89 outputs the target torque value Tp_com that has been subjected to the filter processing according to the characteristic 89a. When the selection of the target torque lines L1 and L12 is switched, switching is performed from the pump target absorption torque (second pump target absorption torque Tp_com2) on the target torque line (for example, the second target torque line L12) before switching. Instead of switching to the pump target absorption torque (first pump target absorption torque Tp_com1) on the subsequent target torque line (first target torque line L1) as it is, before gradually switching over time t Pump target absorption line (second target torque line L12) on the target torque line (first target torque line L1) after switching from the pump target absorption torque (second pump target absorption torque Tp_com2) Smoothly reach the absorption torque (first pump target absorption torque Tp_com1).

  Referring to FIG. 18, from the second pump target absorption torque Tp_com2 at the point G on the second target torque line L12, the first pump target absorption torque Tp_com1 at the point H on the first target torque line L1. It gradually changes over time.

As a result, it is possible to suppress a shock applied to the operator and the vehicle body due to a sudden change in torque, and to eliminate a sense of incongruity in the operational feeling.

  The filter process may be performed in both cases where the determination result of the assist flag determination unit 95 is switched from T to F and when the determination result is switched from F to T. Filter processing may be performed only when it is performed. In particular, when the determination result of the assist flag determination unit 95 is switched from T to F and switched from the second target torque line L12 to the first target torque line L1, if the filter process is not performed, the torque decreases rapidly. In many cases, the operator feels uncomfortable. For this reason, when the determination result is switched from T to F and the second target torque line L12 is switched to the first target torque line L1, it is desirable to perform a filtering process.

  The pump target absorption torque Tp_com output from the filter processing unit 89 is given to the control current calculation unit 67 having the same configuration as that shown in FIG. In the control current calculator 67, a control current pc-epc corresponding to the pump target absorption torque Tp_com is calculated.

  In the storage device, a functional relationship 67a in which the control current pc-epc increases as the pump target absorption torque Tp_com increases is stored in a data table format.

  In the control current calculator 67, the control current pc-epc corresponding to the current pump target absorption torque Tp_com is calculated according to the functional relationship 67a.

  A control current pc-epc is output from the controller 6 to the pump control valve 5 to change the pump control valve 5 via the servo piston. The pump control valve 5 prevents the product of the discharge pressure PRp (kg / cm 2) of the hydraulic pump 3 and the capacity q (cc / rev) of the hydraulic pump 3 from exceeding the pump absorption torque Tp_com corresponding to the control current pc-epc. The tilt angle of the swash plate of the hydraulic pump 3 is PC-controlled.

  According to the second embodiment, as shown in FIG. 18, the first target torque line L1 is set, in which the target absorption torque of the hydraulic pump 3 decreases as the engine target rotational speed decreases. In addition, a second target torque line L12 is set with respect to the first target torque line L1, which increases the pump target absorption torque in the low rotation range.

  Then, the engine speed is controlled so as to coincide with the engine target speed. For example, when it is determined that the load of the hydraulic pump 3 is small from the operation amount of each operation lever 41 to 44, the engine target rotation speed is set to a low rotation speed nD, and the hydraulic pump 3 is determined from the operation amount of each operation lever 41 to 44. When it is determined that the engine load is large, the engine target speed is set to a high speed nE.

  Then, it is determined whether or not the deviation between the target engine speed and the actual engine speed is equal to or greater than a predetermined threshold value, that is, whether or not the generator motor 11 should assist the engine 2.

  When the deviation between the engine target speed and the actual engine speed is not equal to or greater than a predetermined threshold value, the first target torque line L1 is selected, and the first target speed corresponding to the engine target speed is selected. The capacity of the hydraulic pump 3 is controlled so that the pump target absorption torque on the target torque line L1 is obtained.

  For this reason, when the engine target speed is set to the low speed nD, the governor sets the upper limit torque value at a point D that intersects the first target torque line L1 on the regulation line FeD corresponding to the engine target speed nD. The fuel injection amount is increased or decreased so that the engine 2 and the hydraulic pump absorption torque are balanced. Statically, matching is performed at a point D on the first target torque line L1.

  When the target engine speed is set to the high engine speed nE, the governor sets a point E that intersects the first target torque line L1 on the regulation line FeE corresponding to the engine target engine speed nE as the upper limit torque value. The fuel injection amount is increased or decreased so that the engine 2 and the hydraulic pump absorption torque are balanced. Statically, matching is performed at a point E on the first target torque line L1.

  Therefore, when the assist by the generator motor 11 is not performed, the engine 2 is controlled along the target torque line L1 as in the comparative example, so that the fuel efficiency is improved, the pump efficiency and the engine efficiency are improved, the noise is reduced, and the engine stall is increased. Effects such as prevention can be obtained.

  When the deviation between the target engine speed and the actual engine speed is equal to or greater than a predetermined threshold value, the generator motor 11 is electrically operated. As a result of the generator motor 11 being electrically operated, the torque indicated by the broken line in FIG. 18 is added to the engine torque.

  When the threshold value is equal to or greater than the threshold value, the second target torque line L12 is selected so that the pump target absorption torque on the second target torque line L12 corresponding to the engine speed can be obtained. The capacity of the hydraulic pump 3 is controlled.

  The control of the second embodiment will be described in comparison with the first embodiment. Here, for example, consider a case where the operation lever 41 or the like is tilted from the neutral position in order to start excavation work. In this case, it is necessary to increase the engine speed from a low rotation to a high load matching point E of high rotation.

  In the case of Embodiment 1, the engine 2 accelerates along the path LN1 of FIG. In the initial stage of starting the excavation work, it is necessary to operate the work implement or the like while increasing the engine rotation (at the time of transition). In the case of the first embodiment, although the responsiveness of the engine 2 is good, there is no assist by the generator motor 2 and no shift to the second target torque line L12. No. 3 absorption torque will be small. For this reason, the start of movement of the work implement is delayed with respect to the movement of the operation lever, causing a reduction in work efficiency and giving the operator a sense of discomfort.

  When the assist by the generator motor 11 is added to the first embodiment described above, the engine 2 is accelerated along the path LN2. In this case, since there is assistance by the generator motor 2, the absorption torque of the hydraulic pump 3 becomes larger at the initial stage when the engine speed is increased than in the first embodiment. For this reason, the work machine starts to move faster than the operation lever, so that a reduction in work efficiency can be suppressed, and an uncomfortable feeling of operation given to the operator can be reduced. Therefore, as a modification of the second embodiment, it is possible to add only the assist by the generator motor 11 to the first embodiment.

  In the case of Embodiment 2, the engine 2 accelerates along the path LN3 in FIG. According to the second embodiment, the point E is reached from the low rotation speed via the point F on the second target torque line L12. That is, immediately after the operation lever 41 is tilted, the hydraulic pump absorption torque immediately reaches a point F where the torque becomes high, so that the working machine starts to move faster than the operation lever moves. For this reason, the work implement can be instantaneously and powerfully moved without lagging the movement of the operation lever while accelerating the engine 2. This improves work efficiency and does not give the operator a sense of incongruity. If there is no assistance by the generator motor 11 (without the hatched portion shown in FIG. 20) and the transition to the second target torque line L12 is attempted, there is a risk that the engine 2 will be overloaded. In the second embodiment, the transition to the second target torque line L12 is guaranteed on the premise of the assist by the generator motor 11.

  As described above, according to the second embodiment, it is possible to operate a work machine or the like with high responsiveness as intended by the operator while improving engine efficiency, pump efficiency, and the like.

(Embodiment 3)
In the second embodiment described above, the explanation has been made on the assumption that the upper turning body of the construction machine 201 is turned by a hydraulic actuator (hydraulic motor). However, in the third embodiment, the upper turning body of the construction machine 301 is operated. It is equipped with an electric swivel system that swivels with an electric actuator.

  FIG. 21 is a block diagram showing a schematic configuration of a construction machine according to Embodiment 3 of the present invention, and this construction machine 301 is equipped with an electric turning system. As shown in FIG. 21, the construction machine 301 has a PTO shaft 10, a generator motor 11, a capacitor 12, an inverter 13, a rotation sensor 14, and a voltage sensor 15 added to the configuration shown in FIG. Although the electric action and the electric power generation action by the generator motor 11 are performed in the same manner as in the second embodiment, the constituent elements for turning the upper swing body by the electric actuator (the swing motor 103), that is, the generator motor controller 310, a current sensor 311, a turning controller 312, a turning motor 313, and a turning speed sensor 315 are added.

  22 to 25 are control flows showing the contents of control processing performed by the controller 6 of the construction machine 301. The control flow of FIG. 22 corresponds to the control flow of FIG. 12, and the engine target speed ncom shown in FIG. 11 is input.

  As shown in FIG. 22, in the third embodiment, an assist torque limit calculation unit 110, a third pump maximum absorption torque calculation unit 106, and a minimum value selection unit 107 are added to the second embodiment. Instead of the generator motor command value switching unit 87 of the second embodiment, generator motor command value switching units 187 and 287 are provided, and instead of the generator motor torque calculating unit 68 of the second embodiment, a required power generation amount calculation unit 120 is provided. Is provided.

  FIG. 23 is a block diagram illustrating an internal configuration of the assist presence / absence determination unit 90 corresponding to FIG. 13 of the second embodiment, and a description of the same parts as those in FIG. FIG. 24 is a block diagram showing a detailed internal configuration of the assist torque limit calculation unit 110. FIG. 25 is a block diagram illustrating a detailed internal configuration of the required power generation amount calculation unit 120.

  Here, in describing the third embodiment, the engine torque assist action is defined. The engine assist action means that when the governor or fuel injection pump is adjusted to control the engine 2 so that the engine speed reaches a certain target engine speed, the actual engine engine speed quickly reaches the target engine speed. It means that torque is applied to the engine output shaft by the generator motor 11. Here, “adding torque” is not only to add shaft torque to quickly increase the engine speed when accelerating engine rotation, but also to quickly decrease engine speed when decelerating engine rotation. It is also used to include the case where the shaft torque is absorbed.

  That is, in the second embodiment, the engine torque assist operation corresponds to the operation of the generator motor 11 to assist the engine 2 and the generator motor 11 to generate the power to reverse assist the engine 2 in the second embodiment.

  As described in the second embodiment, the effect of the engine torque assist function is that when the engine speed is accelerated, the response of the engine acceleration is improved and the workability is improved. Absorption reduces the engine speed quickly and improves noise and vibration during deceleration of the engine speed. In addition, since the engine shaft torque is absorbed when the engine speed is reduced, the rotational kinetic energy that the inertia around the engine output shaft has can be recovered, resulting in an improvement in energy efficiency. It is done.

  On the other hand, “no engine torque assist operation” means that the generator motor 11 generates electric power and supplies its energy (electric power) to the battery 12 or directly to the swing motor 103 to drive the electric motor. It means that the revolving body is operated.

  As described later, the generator motor controller 310 and the turning controller 312 execute the control to cause the engine torque assist action or not to cause the engine torque assist action as described later, based on a command from the controller 6.

  As shown in FIG. 21, in the third embodiment, a turning motor 313 as an electric motor is connected to the drive shaft of the turning machinery 314, and the turning machinery 314 is driven to drive the turning machinery 314. The upper revolving body is driven and driven to swing through a swing pinion, a swing circle, and the like.

  The turning motor 313 performs a power generation action and an electric action. That is, the turning motor 313 operates as an electric motor and also operates as a generator. When the swing motor 313 operates as an electric motor, the upper swing body performs a swing operation, and when the upper swing body stops swinging, the torque of the upper swing body is absorbed and the swing motor 313 operates as a generator.

  The turning motor 313 is driven and controlled by the turning controller 312. The turning controller 312 is electrically connected to the battery 12 through a DC power supply line and is also electrically connected to the generator motor 310. The generator motor controller 310 is configured to include the function of the inverter 13 of the second embodiment. The turning controller 312 and the generator motor controller 310 are controlled in accordance with a command output from the controller 6.

  The current supplied to the swing motor 313, that is, the swing load current SWG_curr indicating the load of the upper swing body is detected by the current sensor 311. The turning load current SWG_curr detected by the current sensor 311 is input to the controller 6.

  In the third embodiment, when the engine target speed ncom is selected by the minimum value selection unit 65 as in the second embodiment, the process proceeds to the control flow shown in FIG. Executed. Hereinafter, each control example will be described.

(Control example 1)
In this control example 1, the required power generation amount calculation unit 120 calculates the required power generation amount Tgen_com of the generator motor 11 according to the storage state of the battery 12.

  Then, in the assist presence / absence determination unit 90, it is determined whether the generator motor 11 is to perform the engine torque assist operation (determination result T) or whether the engine torque assist operation is not performed (determination result F).

  When the assist presence / absence determination unit 90 determines that the generator motor 11 is to be subjected to engine torque assist (determination result T), the generator motor command value switching unit 187 is switched to the T side, that is, the modulation processing unit 97 side. Then, the generator motor 11 is caused to act as an engine torque assist. In this case, the generator motor speed command value (generator motor target rotation speed) Ngen_com is output from the modulation processing unit 97 to the generator motor controller 310. In response to this, the generator controller 310 controls the rotational speed of the generator motor 11 so that the generator motor target rotational speed Ngen_com is obtained, and causes the generator motor 11 to perform an electric torque action or an engine power assist action. On the other hand, when the assist presence / absence determination unit 90 determines that the generator motor 11 is not to perform the engine torque assist operation (determination result F), the generator motor command value switching unit 187 is switched to the F side to generate the generator motor. 11 is turned off so that the engine torque assist operation is not performed, and the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side. Power generation is performed so that a power generation amount corresponding to the required power generation amount Tgen_com calculated by the required power generation amount calculation unit 120 is obtained. In this case, the required power generation amount Tgen_com is output from the required power generation amount calculation unit 120 to the generator motor controller 310 as a generator motor torque command value (generator motor target torque). In response to this, the generator motor controller 310 controls the torque of the generator motor 11 so that the generator motor target torque Tgen_com is obtained, and causes the generator motor 11 to generate power. In this case, the turning controller 312 performs control to supply the electric power generated by the generator motor 11 to the battery 12 or directly to the turning motor 313 to operate the electric upper turning body.

  As described above, in this control example 1, depending on the necessity of the engine torque assist operation, the generator motor 11 performs the power generation according to the required power generation amount without performing the engine torque assist operation or without performing the engine torque assist operation. Since it did in this way, while being able to maintain stably the amount of electrical storage of the electrical storage device 12 always at the target state, the operativity of a working machine, especially an upper turning body can always be maintained at a high level.

(Control example 2)
In this control example 2, the required power generation amount calculation unit 120 calculates the required power generation amount Tgen_com of the generator motor 11 according to the storage state of the battery 12.

  In the first pump target absorption torque calculation unit 66, a first maximum torque line 66a indicating the maximum absorption torque that can be absorbed by the hydraulic pump 3 is set according to the engine target rotational speed.

  In the second pump target absorption torque calculation unit 85, a second maximum torque line 85a that increases the maximum absorption torque in the engine low rotation region is set with respect to the first maximum torque line 66a.

  Then, in the assist presence / absence determination unit 90, it is determined whether the generator motor 11 is to perform the engine torque assist operation (determination result T) or whether the engine torque assist operation is not performed (determination result F).

  When the assist presence / absence determining unit 90 determines that the generator motor 11 is to be subjected to engine torque assist (determination result T), the pump absorption torque command value switching unit 88 is on the T side, that is, the second pump target absorption torque. The pump is switched to the calculation unit 85 side, the second maximum torque line 85a is selected as the maximum torque line, and the pump absorption torque on the second maximum torque line 85a corresponding to the current engine target rotational speed is the upper limit. The capacity of the hydraulic pump 3 is controlled so that the absorption torque can be obtained. On the other hand, when the assist presence / absence determination unit 90 determines that the generator motor 11 does not perform the engine torque assist operation (determination result F), the pump absorption torque command value switching unit 88 is on the F side, that is, the first pump target. Switching to the absorption torque calculation unit 66 side, the first maximum torque line 66a is selected as the maximum torque line, and the pump absorption torque on the first maximum torque line 66a corresponding to the current engine target speed is set as the upper limit. The capacity of the hydraulic pump 3 is controlled so as to obtain the pump absorption torque. The pump capacity is controlled by outputting a control current pc-epc from the controller 6 to the pump control valve 5 and changing the swash plate of the hydraulic pump 3 via the servo piston, as in the first embodiment.

  When the assist presence / absence determination unit 90 determines that the generator motor 11 is to be subjected to engine torque assist (determination result T), the generator motor command value switching unit 187 is switched to the T side, that is, the modulation processing unit 97 side. Then, the generator motor 11 is caused to act as an engine torque assist. In this case, the generator motor speed command value (generator motor target rotation speed) Ngen_com is output from the modulation processing unit 97 to the generator motor controller 310. In response to this, the generator controller 310 controls the rotational speed of the generator motor 11 so that the generator motor target rotational speed Ngen_com is obtained, and causes the generator motor 11 to perform an electric torque action or an engine power assist action. On the other hand, when the assist presence / absence determination unit 90 determines that the engine motor 11 does not perform the engine torque assist operation (determination result F), the generator motor command value switching unit 187 is switched to the F side, and the generator motor is 11 is turned off so that the engine torque assist operation is not performed, and the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, and the required power generation amount calculation unit The generator motor 11 is caused to generate power so that a power generation amount corresponding to the required power generation amount Tgen_com calculated in 120 is obtained. In this case, the required power generation amount Tgen_com is output from the required power generation amount calculation unit 120 to the generator motor controller 310 as a generator motor torque command value (generator motor target torque). In response to this, the generator motor controller 310 controls the torque of the generator motor 11 so that the generator motor target torque Tgen_com is obtained, and causes the generator motor 11 to generate power. In this case, the turning controller 312 performs control to supply the electric power generated by the generator motor 11 to the battery 12 or directly to the turning motor 313 to operate the electric upper turning body.

  As described above, in this control example 2, as in the control example 1, depending on the necessity of the engine torque assist operation, the engine torque assist operation is performed, or the power generation corresponding to the required power generation amount is performed without performing the engine torque assist operation. Is generated by the generator motor 11, so that the amount of electricity stored in the battery 12 can be stably maintained in a target state at all times, and the operability of the working machine, particularly the upper-part turning body, can always be maintained at a high level. .

  Moreover, in the control example 2, the pump on the second maximum torque line 85a in which the maximum absorption torque is increased in the engine low rotation region with respect to the first maximum torque line 66a while the engine torque assisting action is performed by the generator motor 11. Since the capacity of the hydraulic pump 3 is controlled so as to obtain the pump absorption torque whose upper limit is the absorption torque, the absorption torque of the hydraulic pump 3 at the initial stage when the engine speed is increased can be increased. For this reason, the working machine starts to move quickly with respect to the movement of the operation lever, and it is possible to suppress a decrease in work efficiency and to reduce the uncomfortable feeling of operation given to the operator. As described in the second embodiment, if an attempt is made to perform control according to the second maximum torque line L12 without causing the generator motor 11 to perform the engine torque assist operation, the engine 2 may be overloaded. That is, if the capacity of the hydraulic pump 3 is controlled according to the second maximum torque line 85a without the engine torque assisting action, the hydraulic pump 3 absorbs torque exceeding the output of the engine alone, and the engine Not only can the engine speed not be increased, but the engine speed may decrease due to a high load, leading to an engine stall in the worst case. As described above, in the control example 2, the control according to the second maximum torque line 85a is guaranteed on the premise of the engine torque assist action by the generator motor 11.

(Control example 3)
In the control example 1 and the control example 2 described above, the assist presence / absence determination unit 90 specifically performs the determination as shown in FIG. That is, in the first determination unit 92, when the absolute value of the deviation Δgen_spd between the generator motor target rotational speed Ngen_com and the generator motor actual rotational speed GEN_spd exceeds a predetermined threshold, that is, the engine target rotational speed and the engine 2 When the absolute value of the deviation from the actual rotational speed is equal to or greater than a predetermined threshold value, it is determined that the generator motor 11 is to perform the engine torque assist operation, and the assist flag assist_flag is set to T. On the other hand, when the absolute value of the deviation Δgen_spd between the generator motor target rotational speed Ngen_com and the generator motor actual rotational speed GEN_spd falls below a predetermined threshold, that is, the engine target rotational speed and the actual rotational speed of the engine 2 Is smaller than a predetermined threshold value, it is determined that the generator motor 11 is not subjected to engine torque assist, and the assist flag is set to F.

  When the rotational speed deviation Δgen_spd becomes greater than a certain value with a sign plus, the generator motor 11 is electrically operated to assist the engine 2. As a result, when the current engine speed is different from the target speed, the engine speed rapidly increases toward the engine target speed. When the rotational speed deviation Δgen_spd is a sign minus and increases to a certain degree or more, the generator motor 11 is caused to generate power and the engine 2 is reversely assisted. As a result, power is generated when the engine speed is decelerated, the engine speed is rapidly reduced, and the energy of the engine 2 is regenerated.

  As described above, in this control example 3, since the threshold value is provided for the deviation and it is determined whether or not the engine torque assist operation is performed, the control is stabilized. In other words, if the engine torque assist action is performed immediately when there is a deviation without setting a threshold for the deviation, the engine torque assist action is continued at an engine speed near the engine target speed. , Leading to energy loss. This is because the energy source for the engine torque assisting action is originally the energy of the engine 2, so that the engine torque assisting action always increases the energy loss by the efficiency of the generator motor 11. Generally, when the generator motor 11 is driven and generated with a small torque, the efficiency decreases.

(Control example 4)
In the control example 1 and the control example 2 described above, the assist presence / absence determination unit 90 specifically performs the determination as shown in FIG. That is, in the second determination unit 93, when the voltage value BATT_volt of the battery 12, that is, when the stored amount is equal to or less than the predetermined threshold value BC1, it is determined that the generator motor motivation 11 does not act on the engine torque, and the assist flag assist_flag To F. As described above, by preventing the engine torque assist operation when the storage amount of the storage battery 12 is low, overdischarge of the storage battery 12 can be avoided, and a decrease in the life of the storage battery 12 can be avoided. In particular, Embodiment 3 is based on the assumption that the electric swing system is used, and therefore, energy storage energy is required to rotate the upper swing body. If the amount of stored energy is excessively reduced, the turning performance is adversely affected. By preventing the engine torque assist operation when the amount of electricity stored in the battery 12 is low, it is possible to avoid deterioration in turning performance due to a reduction in the amount of electricity stored.

(Control example 5)
In the control example 1 and the control example 2 described above, the assist presence / absence determination unit 90 specifically performs the determination as shown in FIG. That is, in the turning output calculation unit 95, the current output SWG_pow of the turning motor 313 is calculated using the turning load current SWG_curr and the voltage value BATT_volt of the battery 12 according to the following equation (5).

SWGpow = SWGcurr × BATT_volt × Kswg (5)
Kswg is a constant.

  Then, in the third determination unit 96, when the current output SWG_pow of the turning motor 103 is equal to or greater than the predetermined threshold value SC1, it is determined that the generator motor 11 is not operated with the engine torque assist, and the assist flag assist_flag is set to F. To. In addition, when the current output SWG_pow of the swing motor 313 is equal to or less than the threshold value SC2 that is smaller than the threshold value SC1, it is determined that the generator motor 11 is to perform the engine torque assist operation, and the assist flag assist_flag is set to T. . Thus, by providing hysteresis between the threshold value SC1 and the threshold value SC2, control hunting is prevented.

  In the AND circuit 94, the assist flag assist_flag obtained by the first determination unit 92, the assist flag assist_flag obtained by the second determination unit 93, and the assist flag assist_flag obtained by the third determination unit 96 are both included. In the case of T, the content of the assist flag assist_flag is finally set to T, and when either is F, the content of the assist flag assist_flag is finally set to F.

  On the other hand, as shown in FIG. 25, the required power generation amount calculation unit 120 generates power according to the voltage value BATT_volt of the battery 12, that is, the storage state of the battery 12, and the swing load current SWG_curr, that is, the drive state of the swing motor 313. The required power generation amount Tgen_com of the electric motor 11 is calculated.

  In the case of the electric turning system, electric energy is required to turn the upper turning body. In order to turn the upper swing body at a high output, the stored energy of the battery 12 is not sufficient, but the generator motor 11 must be operated to supply electric power to the swing motor 313. This means that the required power generation amount calculation unit 120 considers not only the storage state (voltage value BATT_volt) of the battery 12 but also the drive state (turning load current SWG_curr) of the swing motor 11.

  According to this control example 5, when the current output SWG_pow of the turning motor 313 is equal to or greater than the predetermined threshold value SC1, it is determined that the generator motor 11 is not to perform the engine torque assist operation, and the engine torque assist operation is prohibited. On the other hand, the required power generation amount Tgen_com of the generator motor 11 is calculated in consideration of not only the power storage state (voltage value BATTvolt) of the battery 12 but also the driving state (swing load current SWG_curr) of the swing motor 313, and this required power generation amount Tgen_com The generator motor 11 generates power in accordance with the power, and the generated power is supplied to the turning motor 313. For this reason, it is possible to turn the upper turning body without lowering the turning performance.

(Control example 6)
As described above, when the rotational speed deviation Δgen_spd is larger than a certain value with a sign plus, the generator motor speed command value (generator motor target rotational speed) Ngen_com is output from the modulation processing unit 97 to the generator motor controller 310, In response to this, the generator controller 310 controls the number of revolutions of the generator motor 11 so that the generator motor target revolution number Ngen_com is obtained, and causes the generator motor 11 to be electrically operated. That is, when the current engine speed is smaller than the engine target speed, the generator motor 11 is electrically operated, and the shaft torque of the engine 2 is added on the torque diagram of the engine 2 to increase the engine speed. The output torque of the generator motor 11 is controlled so that the engine speed is equal to the target engine speed.

  In addition, when the rotation speed deviation Δgen_spd is minus with a sign minus, the generator motor speed command value (generator motor target rotation speed) Ngen_com is output from the modulation processing unit 97 to the generator motor controller 310, and the generator In response to this, the controller 310 controls the rotational speed of the generator motor 11 so that the generator motor target rotational speed Ngen_com is obtained, and causes the generator motor 11 to generate power. That is, when the current engine speed is greater than the engine target speed, the generator motor 11 is caused to generate power, absorb the shaft torque of the engine 2 on the engine torque diagram, and decrease the engine speed. The output torque of the generator motor 11 is controlled so that the rotation speed is equal to the engine target rotation speed.

(Control example 7)
As described above, when the assist presence / absence determination unit 90 determines that the voltage value BATT_volt of the battery 12, that is, the stored amount is equal to or less than the predetermined threshold value BC <b> 1, the generator motor 11 does not perform the engine torque assist operation (determination result). F), the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, and the power generation amount corresponding to the required power generation amount Tgen_com calculated by the required power generation amount calculation unit 120 is obtained. The generator motor 11 generates power so as to be obtained.

  However, if the amount of electricity stored in the battery 12 reaches a threshold value or less, the engine torque assist operation is immediately prohibited, and the power generation operation corresponding to the required power generation amount is performed from the state where the engine torque assist operation is being performed. If it is suddenly switched to a state where the engine 2 is running, a sudden load may be applied to the output shaft of the engine 2. For this reason, the engine 2 cannot cope with the sudden load, the output of torque cannot catch up, and the engine speed may suddenly decrease. A sudden decrease in the engine speed leads to a decrease in the output of the work machine, which is undesirable in terms of work efficiency.

  Therefore, in this control example 7, before switching from the state in which the engine torque assist operation is performed to the state in which the power generation operation according to the required power generation amount is performed, the upper limit value (torque limit) of the torque that can be generated by the generator motor 11 is set. Then, the value is gradually decreased according to the decrease in the charged amount (voltage value BATT_volt) of the battery 12. Specifically, as shown in FIG. 24, in the calculation unit 111 of the assist torque limit calculation unit 110, the voltage value BATT_volt of the battery 12 is a second value that is smaller than the first predetermined value BD1 from the first predetermined value BD1. As the value decreases to the predetermined value BD2, the torque upper limit value (generator motor torque limit) GEN_trq_limit of the generator motor 11 is obtained as a value that is gradually reduced and output.

  When it is determined that the generator motor 11 is to be subjected to engine torque assist (determination result T) and the generator motor command value switching unit 287 is switched to the T side, that is, the assist torque limit calculation unit 110 side, the assist torque limit calculation is performed. The generator motor torque limit GEN_trq_limit is output from the unit 110 to the generator motor controller 310 as a limit value of the generator motor torque command value (generator motor target torque) Tgen_com.

  When it is determined that the engine torque assist operation is to be performed, the generator motor 11 operates by speed control so as to obtain the target rotational speed. The generator motor torque command value (generator motor target torque) Tgen_com of the generator motor 11 is calculated as a result of the speed control loop.

  The generator motor controller 310 prevents the generator motor torque command value (generator motor target torque) Tgen_com calculated from the speed control loop from exceeding the generator motor torque limit GEN_trq_limit calculated by the assist torque limit calculator 110. 11 to control the generator motor 11 to assist. That is, the torque of the generator motor 11 is controlled within the range of the torque upper limit value GEN_trq_limit or less. Then, when the voltage value BATT_volt of the battery 12 becomes equal to or less than the predetermined threshold value BC1, and the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, the required power generation amount calculation unit 120. The generator motor 11 is caused to generate power so as to obtain a power generation amount corresponding to the required power generation amount Tgencom calculated in (1). In this case, the required power generation amount Tgen_com is output from the required power generation amount calculation unit 120 to the generator motor controller 310 as a generator motor torque command value (generator motor target torque). In response to this, the generator motor controller 100 controls the torque of the generator motor 11 so that the generator motor target torque Tgen_com is obtained, and causes the generator motor 11 to generate power. Thus, in this control example 7, before switching from the state in which the engine torque assist operation is performed to the state in which the power generation operation according to the required power generation amount is performed, the upper limit value of the torque that can be generated by the generator motor 11 (torque limit) ) Since GEN_trq_limit is gradually decreased according to the decrease in the storage amount (voltage value BATT_volt) of the capacitor 12, the power generation operation according to the required power generation amount is performed from the state where the engine torque assist operation is performed The change in the power generation torque of the generator motor 11 at the time of switching to becomes smooth, and it can be avoided that the engine speed decreases during this switching.

(Control example 8)
In this control example 8, the following control is performed by the calculation unit 111 of the assist torque limit calculation unit 110 in the control example 7 described above. That is, as the voltage value BATT_volt of the battery 12 decreases from the first predetermined value BD1 to the second predetermined value BD2 smaller than the first predetermined value BD1, the torque upper limit value (generator motor torque limit) of the generator motor 11 While GEN_trq_limit is obtained and output as a value that is gradually reduced, when the torque upper limit value GEN_trq_limit once reduced is increased, the voltage value BATT_volt of the battery 12 is changed from the third predetermined value BD3 to the third predetermined value BD3. The torque upper limit value (generator motor torque limit) GEN_trq_limit of the generator motor 11 is obtained as a value that is gradually increased as it increases to a fourth predetermined value BD4 that is larger than the predetermined value BD3, and is output.

  As described above, by giving hysteresis to the method of changing the generator motor torque limit GEN_trq_limit, the control can be stably performed.

(Control example 9)
As described above, when the assist presence / absence determination unit 90 determines that the current output SWG_pow of the turning motor 103 is equal to or greater than the predetermined threshold value SC1, the generator motor 11 is not allowed to act on the engine torque (determination result F). The generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, and a power generation amount corresponding to the required power generation amount Tgen_com calculated by the required power generation amount calculation unit 120 is obtained. Thus, the generator motor 11 generates power.

  Here, as in Control Example 7, when the current output SWG_pow of the turning motor 313 reaches a predetermined threshold value SC1 or more, the engine torque assist operation is immediately prohibited and requested from the state where the engine torque assist operation is being performed. If the power generation action corresponding to the amount of power generation is suddenly switched, a sudden load may be applied to the output shaft of the engine 2. For this reason, the engine 2 cannot cope with the sudden load, the output of torque cannot catch up, and the engine speed may suddenly decrease. A sudden decrease in the engine speed leads to a decrease in the output of the work machine, which is undesirable in terms of work efficiency.

  In Control Example 9, as in Control Example 7, the upper limit value of the torque that can be generated by the generator motor 11 before switching from the state in which the engine torque assist operation is performed to the state in which the power generation operation according to the required power generation amount is performed. (Torque limit) is gradually made smaller as the current output SWG_pow of the swing electric motor 11 increases.

  Specifically, as shown in FIG. 24, in the turning output calculation unit 112 of the assist torque limit calculation unit 110, the current output SWG_pow of the turning motor 313 is the above-described equation (5) (SWG_pow = SWG_curr × BATT_volt × Kswg). Next, in the calculation unit 113, as the current output SWG_pow of the swing motor 313 increases from the first predetermined value SD1 to the second predetermined value SD2 that is larger than the first predetermined value SD1, the generator motor The torque upper limit value (generator motor torque limit) GEN_trq_limit of 11 is obtained as a value that is gradually reduced and output.

  The smaller value of the torque upper limit value GEN_trq_limit determined by the calculation unit 111 and the torque upper limit value GEN_trq_limit determined by the calculation unit 113 is selected by the minimum value selection unit 114 to obtain the final torque upper limit value (generator motor Torque limit GEN_trq_limit) is output from the assist torque limit calculation unit 110.

  When it is determined that the generator motor 11 is to be subjected to engine torque assist (determination result T) and the generator motor command value switching unit 287 is switched to the T side, that is, the assist torque limit calculation unit 110 side, the assist torque limit calculation is performed. The generator motor torque limit GEN_trq_limit is output from the unit 110 to the generator motor controller 310 as a limit value of the generator motor torque command value (generator motor target torque) Tgen_com.

  When it is determined that the engine torque assist operation is to be performed, the generator motor 11 operates by speed control so as to obtain the target rotational speed. The generator motor torque command value (generator motor target torque) Tgen_com of the generator motor 11 is calculated as a result of the speed control loop.

  The generator motor controller 310 prevents the generator motor torque command value (generator motor target torque) Tgen_com calculated from the speed control loop from exceeding the generator motor torque limit GEN_trq_limit calculated by the assist torque limit calculator 110. 11 to control the generator motor 11 to assist. That is, the torque of the generator motor 11 is controlled within the range of the torque upper limit value GEN_trq_limit or less.

  When the current output SWG_pow of the swing motor 313 becomes equal to or greater than the predetermined threshold value SC1 and the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, the required power generation amount calculation is performed. The generator motor 11 generates power so that a power generation amount corresponding to the required power generation amount Tgen_com calculated by the unit 120 is obtained. In this case, the required power generation amount Tgen_com is output from the required power generation amount calculation unit 120 to the generator motor controller 310 as a generator motor torque command value (generator motor target torque). In response to this, the generator motor controller 310 controls the torque of the generator motor 11 so that the generator motor target torque Tgen_com is obtained, and causes the generator motor 11 to generate power. Thus, in this control example 9, before switching from the state in which the engine torque assist operation is performed to the state in which the power generation operation according to the required power generation amount is performed, the upper limit value of the torque that can be generated by the generator motor 11 (torque limit) ) Since GEN_trq_limit is gradually decreased as the current output SWG_pow of the swing motor 313 increases, the engine torque assist operation is switched to the power generation operation corresponding to the required power generation amount. It is possible to avoid a change in the power generation torque of the generator motor 11 at the time and a decrease in the engine speed during the switching.

(Control example 10)
In this control example 10, the following control is performed by the calculation unit 113 of the assist torque limit calculation unit 110 in the control example 9 described above. That is, as the current output SWG_pow of the swing motor 313 increases from the first predetermined value SD1 to the second predetermined value SD2 that is larger than the first predetermined value SD1, the torque upper limit value (generator motor torque) of the generator motor 11 is increased. Limit) GEN_trq_limit is obtained and outputted as a value that is gradually reduced, while when the torque upper limit value GEN_trq_limit once reduced is increased, the current output SWG_pow of the swing motor 313 is the third predetermined value SD3 To the fourth predetermined value SD4 smaller than the third predetermined value SD3, the torque upper limit value (generator motor torque limit) GEN_trq_limit of the generator motor 11 is obtained as a value that is gradually increased and output. The

  As described above, by giving hysteresis to the method of changing the generator motor torque limit GEN_trq_limit, the control can be stably performed.

(Control Example 11)
As described above, when the assist presence / absence determination unit 90 determines that the voltage value BATT_volt of the battery 12 is equal to or lower than the predetermined threshold value BC1, or the current output SWG_pow of the swing motor 313 is equal to or higher than the predetermined threshold value SC1. When it is determined, it is determined that the generator motor 11 is not allowed to act on the engine torque (determination result F), and the generator motor command value switching unit 287 is switched to the F side, that is, the required power generation amount calculation unit 120 side, and the request is made. The generator motor 11 generates power so that a power generation amount corresponding to the required power generation amount Tgen_com calculated by the power generation amount calculation unit 120 is obtained.

  Here, when the voltage value BATT_volt of the battery 12 reaches a predetermined threshold value BC1 or less, or the current output SWG_pow of the swing motor 313 reaches a predetermined threshold value SC1 or more, the engine torque assist operation is immediately prohibited. If the engine torque assist operation is suddenly switched to the power generation operation corresponding to the required power generation amount, a sudden load may be applied to the output shaft of the engine 2. For this reason, the engine 2 cannot cope with the sudden load, the output of torque cannot catch up, and the engine speed may suddenly decrease. A sudden decrease in the engine speed leads to a decrease in the output of the work machine, which is undesirable in terms of work efficiency.

  In this control example 11, instead of implementing the control example 7, the control example 8, the control example 9 and the control example 10, or together with the implementation of each of these control examples, the required power generation amount from the state where the engine torque assist action is being performed. Immediately after switching to the state in which the power generation action according to the operation is performed, control is performed to gradually change the power generation torque of the generator motor 11 from the torque at the end of the assist to the power generation torque corresponding to the required power generation amount of the generator motor 11. This avoids a sudden drop in engine speed during the switching.

  Specifically, as shown in FIG. 25, in the calculation unit 121 of the required power generation amount calculation unit 120, the voltage value BATT_volt of the battery 12 is a second value that is smaller than the first predetermined value BE1 from the first predetermined value BE1. As the predetermined power value BE2 decreases, the required power generation output P is obtained and output as a value that gradually increases from zero output to the power generation output Pmax corresponding to the required power generation amount of the generator motor 11. Here, when the required power generation output P once increased is decreased, the voltage value BATTvolt of the battery 12 is increased from the third predetermined value BE3 to the fourth predetermined value BE4 which is larger than the third predetermined value BE3. Accordingly, the required power generation output P is obtained as a value that gradually decreases and is output.

  Thus, by giving hysteresis to the way of changing the required power generation output P, the control is stably performed.

  On the other hand, in the turning output calculation unit 122, the current output SWG_pow of the turning motor 313 is calculated by using the turning load current SWG_curr and the voltage value BATT_volt of the battery 12 (5) (SWG_pow = SWG_curr × BATT_volt × Kswg). Is required. Next, in the calculation unit 123, as the current output SWG_pow of the swing motor 313 increases from the first predetermined value SE1 to the second predetermined value SE2 that is larger than the first predetermined value SE1, the required power generation output P is increased. It is obtained and output as a value that is gradually increased from zero output to the power generation output Pmax corresponding to the required power generation amount of the generator motor 11. Here, when the required power generation output P once increased is decreased, the current output SWG_pow of the swing motor 103 is from the third predetermined value SE3 to the fourth predetermined value SE4 smaller than the third predetermined value SE3. The required power generation output P is obtained as a value that gradually decreases as the power decreases, and is output.

  Thus, by giving hysteresis to the way of changing the required power generation output P, the control is stably performed.

  The larger value of the required power generation output P obtained by the calculation unit 121 and the required power generation output P obtained by the calculation unit 123 is selected by the maximum value selection unit 124, and as the final required power generation output Pgen_com, It is added to the generator motor required power generation torque calculator 125. The generator motor required power generation torque calculation unit 125 calculates the generator motor required power generation torque Tgen_com by the following equation (6) using the generator motor rotation speed GEN_spd and the required power generation output Pgen_com.

Tgen_com = Pgen_com ÷ GEN_spd × Kgen (6)
Kgen is a constant.

  From the required power generation amount calculation unit 120, the generator motor required power generation torque Tgen_com finally obtained by the above equation (6), that is, the power generation torque of the generator motor 11 is gradually generated from zero torque according to the required power generation amount of the generator motor. The required power generation torque Tgen_com that increases the torque is output.

  When the voltage value BATT_volt of the battery 12 reaches a predetermined threshold value BC1 or less, or when the current output SWG_pow of the swing motor 103 reaches a predetermined threshold value SC1 or more, the generator motor command value switching unit 287 is switched to the F side. That is, it is switched to the required power generation amount calculation unit 120 side.

  Immediately after this switching, as described above, the required power generation torque for gradually increasing the power generation torque of the generator motor 11 from zero torque to the power generation torque corresponding to the required power generation amount of the generator motor 11, that is, the required power generation amount Tgen_com is the generator motor torque. The command value (generator motor target torque) is output to the generator motor controller 310. In response to this, the generator motor controller 310 controls the torque of the generator motor 11 so that the generator motor target torque Tgen_com is obtained, and causes the generator motor 11 to generate power.

  Thus, in this control example 11, immediately after switching from the state in which the engine torque assist operation is performed to the state in which the power generation operation according to the required power generation amount is performed, the power generation torque of the generator motor 11 is gradually generated from zero torque. Since the control to increase the power generation torque according to the required power generation amount of the electric motor 11 is performed, the power generation at the time of switching from the state where the engine torque assist operation is performed to the state where the power generation operation according to the required power generation amount is performed The change in the power generation torque of the electric motor 11 becomes smooth, and it can be avoided that the engine speed decreases at the time of switching.

(Control example 12)
In the control examples 7, 8, 9, and 10, the control for gradually decreasing the torque limit value of the generator motor 11 during the engine torque assist operation has been described.

  However, if the control for gradually decreasing the torque upper limit value (torque limit value) of the generator motor 11 during the engine torque assist operation is performed, the force for assisting the engine 2 gradually decreases. The acceleration of the engine 2 is deteriorated when switching from the operated state to the state where the power generation operation corresponding to the required power generation amount is performed.

  Therefore, in this control example 12, the assist force of the engine 2 is controlled by controlling the capacity of the hydraulic pump 3 so that the maximum absorption torque of the hydraulic pump 3 is gradually reduced as the torque upper limit value of the generator motor 11 decreases. The absorption torque of the hydraulic pump 3 is reduced in accordance with the decrease of the engine speed, and the deterioration of the engine speed acceleration accompanying the decrease of the assist force of the engine 2 is avoided.

  That is, as shown in FIG. 22, the assist torque limit calculation unit 110 outputs the generator motor torque limit GEN_trq_limit to the third pump maximum absorption torque calculation unit 106 as the torque upper limit value Tgen_com2 of the generator motor 11. . The third pump maximum absorption torque calculator 106 gradually decreases the maximum absorption torque (third pump maximum absorption torque) Tp_commax of the hydraulic pump 3 as the generator generator torque limit GEN_trq_limit of the generator motor 11 decreases. The third maximum torque line L3 is stored in a data table format as a functional relationship 106a between the generator / generator torque limit GEN_trq_limit and the third pump maximum absorption torque Tp_commax. In the third pump maximum absorption torque calculator 106, the third pump maximum absorption torque Tp_commax corresponding to the current generator generator torque limit GEN_trq_limit of the generator motor 11 is calculated according to the functional relationship 106a.

  On the other hand, the first pump maximum absorption torque (first pump target absorption torque) Tp_com1 is calculated by the first pump target absorption torque calculator 66 on the first maximum torque line (first target torque line) L1. The value is calculated according to the function relation 66a.

  The second pump maximum absorption torque (second pump target absorption torque) Tp_com2 is calculated by the second pump target absorption torque calculation unit 85 on the second maximum torque line (second target torque line) L12. The value is calculated according to the functional relationship 85a.

  The minimum value selection unit 107 selects a pump maximum absorption torque value which is smaller between the current third pump maximum absorption torque Tp_commax and the current second pump maximum absorption torque Tp_com2, and receives a pump absorption torque command value. It is output to the T side terminal of the switching unit 88.

  The current first pump maximum absorption torque Tp_com is applied to the F-side terminal of the pump absorption torque command value switching unit 88.

  When the assist flag determination unit 95 determines that the content of the assist flag assist_flag is T, the pump absorption torque command value switching unit 88 is switched to the minimum value selection unit 107 side, and the second pump target absorption torque calculation unit Of the current second pump maximum absorption torque Tpcom2 output from 85 and the current third pump maximum absorption torque Tp_commax output from the third pump maximum absorption torque calculator 106, the smaller value is the pump. The maximum absorption torque Tp_com is output to the subsequent filter processing unit 89.

  When the assist flag determination unit 95 determines that the content of the assist flag assist_flag is F, the pump absorption torque command value switching unit 88 is switched to the first pump target absorption torque calculation unit 66 side, and the first The current first pump maximum absorption torque Tpcom1 output from the pump target absorption torque calculating unit 66 is output to the subsequent filter processing unit 89 as the pump maximum absorption torque Tp_com. Thereafter, the filter processing unit 89 performs the above-described filter processing, the control current calculation unit 67 outputs the control current pc-epc to the pump control valve 5, and the swash plate 3a of the hydraulic pump 3 is adjusted. That is, when the power generation operation is performed, the first pump maximum absorption torque Tp_com1 determined from the first maximum torque line L1 regardless of the magnitude of the third pump maximum absorption torque Tp_commax determined from the third maximum torque line L3. Is selected, and the capacity of the hydraulic pump 3 is controlled using the first pump maximum absorption torque Tp_com1 as the upper limit Tp_com of the pump absorption torque. On the other hand, when the engine torque assist operation is performed, the second pump maximum absorption torque Tp_com2 determined from the second maximum torque line L12 and the third pump maximum absorption torque Tp_commax determined from the third maximum torque line L3 are smaller. Is selected, and the capacity of the hydraulic pump 3 is controlled using the smaller pump maximum absorption torque as the upper limit Tp_com of the pump absorption torque.

  Thus, according to this control example, the capacity of the hydraulic pump 3 is controlled so that the maximum absorption torque of the hydraulic pump 3 is gradually reduced as the torque upper limit value of the generator motor 11 decreases. When the engine torque assist operation is switched to the power generation operation corresponding to the required power generation amount, the absorption torque of the hydraulic pump 3 decreases in accordance with the decrease in the assist force of the engine 2 and the shaft of the engine 2 The change in torque becomes smooth, and it is possible to avoid deterioration in acceleration of the engine speed associated with a decrease in the assist force of the engine 2.

(Control Example 13)
As described above, at the time of switching between the state in which the engine torque assist operation is performed and the state in which the power generation operation according to the required power generation amount is performed, the selection of the maximum absorption torque of the hydraulic pump 3 is the second pump maximum The absorption torque Tp_com2 or the third pump maximum absorption torque Tp_commax is switched between the first pump maximum absorption torque Tp_com1. For this reason, at the time of switching, an abrupt change in the pump absorption torque may give the operator a sense of incongruity in operation, such as a rattling of the work implement speed due to a change in pump discharge flow rate.

  Therefore, in this control example, when the selection of the maximum absorption torque of the hydraulic pump 3 is switched, control is performed to gradually change from the pump maximum absorption torque before switching to the pump maximum absorption torque after switching. Thus, it is intended to prevent a sudden change in the pump discharge flow rate at the time of switching, and to avoid an uncomfortable feeling in operation for the operator, such as a rattling of the work machine speed.

  That is, as shown in FIG. 22, when the selection of the maximum torque line is switched between the second maximum torque line L12 or the third maximum torque line L3 and the first maximum torque line L1, the filter processing unit In 89, the maximum torque value Tpcom is gradually changed according to the characteristic 89a in which the maximum torque value Tp_com changes with the passage of time t. The characteristic 89a has a curve corresponding to the time constant τ. Accordingly, the maximum torque line after switching (first maximum torque line) from the pump maximum absorption torque (third pump maximum absorption torque Tp_commax) on the maximum torque line before switching (for example, the third target torque line L3). L1) The pump maximum absorption torque (first pump maximum absorption torque Tp_com1) on the maximum torque line (for example, the third target torque line L3) before switching is not directly switched to the pump maximum absorption torque (first pump maximum absorption torque Tp_com1). 3 gradually from the pump maximum absorption torque Tp_commax (3) to the pump maximum absorption torque (first pump maximum absorption torque Tpcom1) on the maximum torque line (first maximum torque line L1) after switching. It will change smoothly. The movement on the torque diagram is the same as described above with reference to FIG.

  As a result, a sudden change in the pump absorption torque at the time of switching between the state where the engine torque assisting action is being performed and the state where the power generation action is being performed according to the required power generation amount causes a change in the work machine speed due to the change in pump discharge flow rate. It is possible to avoid a sense of incongruity in operation for the operator, such as a backlash.

  The filter processing described above may be performed in both cases where the determination result of the assist flag determination unit 95 is switched from T to F, and when the determination result is switched from F to T. Filter processing may be performed only when switching is performed.

(Control example 14)
In the above control example 13, the time constant τ when changing from the pump maximum absorption torque before switching to the pump maximum absorption torque after switching is such that the pump maximum absorption torque before switching is higher than the pump maximum absorption torque after switching. It is desirable to set a larger value when the pump maximum absorption torque before switching is larger than the pump maximum absorption torque after switching, rather than when it is small.

  This is because when the time constant τ is uniformly set to a large value, when the pump maximum absorption torque is switched from a small state to a large state, the time constant of the change in the pump maximum absorption torque is large. Because it becomes dull.

  Also in the third embodiment, when assist_flag is true, the engine target rotation speed addition value calculation unit 104 is notified, and the engine target rotation speed addition value calculation unit 104 determines the engine target rotation speed addition value ncom_add. No additional output is performed.

It is a block diagram which shows schematic structure of the construction machine concerning Embodiment 1 of this invention. It is a figure which shows the control flow of the controller shown in FIG. It is a figure which shows the control flow of the target flow volume calculating part shown in FIG. It is a flowchart which shows the process sequence of the engine target rotational speed addition value calculating part shown in FIG. FIG. 3 is a diagram illustrating an example of processing of a target rotation speed addition value calculation unit illustrated in FIG. 2. It is a figure which shows the processing flow of the pump output restriction | limiting calculating part shown in FIG. It is a torque diagram for demonstrating the process by an engine target rotation speed addition value calculating part. It is a figure which shows the time change of an engine speed and engine torque for demonstrating the process by an engine target speed addition value calculating part. It is a figure explaining the pump output limit value corresponding to each work pattern. It is a block diagram which shows schematic structure of the construction machine concerning Embodiment 2 of this invention. FIG. 11 is a diagram showing a control flow of the controller shown in FIG. 10 (No. 1). FIG. 11 is a diagram showing a control flow of the controller shown in FIG. 10 (part 2). It is a figure which shows the processing flow of an assist presence determination part. It is a figure explaining operation | movement when there is no modulation process at the time of engine acceleration. It is a figure explaining operation | movement in case there exists a modulation process at the time of engine acceleration. It is a figure explaining operation | movement when there is no modulation process at the time of engine deceleration. It is a figure explaining operation | movement in case there exists a modulation process at the time of engine deceleration. It is a torque diagram used in order to explain Embodiment 2 of this invention. It is a torque diagram used in order to explain Embodiment 2 of this invention. It is a torque diagram used in order to explain Embodiment 2 of this invention. It is a block diagram which shows schematic structure of the construction machine concerning Embodiment 3 of this invention. It is a figure which shows a part of control flow of the controller shown in FIG. It is a figure which shows the processing flow of the assistance presence determination part shown in FIG. It is a figure which shows the processing flow of an assist torque limit calculating part. It is a figure which shows the processing flow of a request | requirement electric power generation amount calculating part. It is a block diagram which shows the schematic structure of the conventional construction machine. It is the torque diagram used in order to demonstrate a prior art.

Explanation of symbols

1, 201, 301 Construction machine 2 Engine 3 Hydraulic pump 4 Engine controller 5 Pump control valve 6 Controller 7-9 Hydraulic sensor 41, 42 Operation lever 43, 44 Travel lever 10 PTO shaft 11 Generator motor 12 Accumulator 31-36 Hydraulic actuator 101 Filter 102 Engine output calculation unit 103 Target engine output calculation unit 104 Engine target rotation speed addition value calculation unit 105 Addition unit 106 Branch unit 310 Generator controller 312 Turning controller 313 Turning motor 314 Turning machinery

Claims (10)

A hydraulic pump driven by an engine;
A hydraulic actuator to which pressure oil discharged from the hydraulic pump is supplied;
Operating means for operating each hydraulic actuator;
Engine target speed setting means for setting an engine target speed of the engine in accordance with an operation amount of the operating means or a setting value of a fuel dial;
Engine output calculation means for calculating the current engine output from the current engine torque estimated from the current engine speed and the fuel injection amount for the current engine;
Based on the relationship between the engine speed and a load-sensing horsepower line that is lower by a predetermined horsepower than the target horsepower line determined in advance for the engine speed, the engine target on the load-sensing horsepower line with respect to the engine target speed Engine target output calculating means for calculating output;
The engine output calculated by the engine output calculation means is compared with the engine target output calculated by the engine target output calculation means, an engine target rotation speed addition value is obtained based on the comparison calculation result, and the engine target rotation An engine control means for obtaining a corrected engine target rotational speed obtained by adding the engine target rotational speed addition value to the number and controlling the engine rotational speed so as to coincide with the corrected engine target rotational speed;
An engine control device comprising: The engine target output calculation means sequentially inputs the corrected engine target rotation speed as the engine target rotation speed, sequentially calculates the engine target output on the load sensing horsepower line with respect to the input engine target rotation speed,
The engine control means sequentially compares and calculates the engine output calculated by the engine output calculation means and the engine target output calculated by the engine target output calculation means, and based on the comparison calculation result, the corrected engine target speed The engine control device according to claim 1, wherein the engine speed is controlled so that the engine speed is matched with the updated corrected engine target speed. When the engine output calculated by the engine output calculation means exceeds the engine target output calculated by the engine target output calculation means, the engine control means adds the previous engine target rotational speed addition value from the engine output to the engine output. The difference engine speed corresponding to the value obtained by subtracting the engine target output is cumulatively added, and this cumulatively added engine target speed addition value is added to the engine target speed, and this added value is used as the corrected engine target speed. 3. The engine control device according to claim 1, wherein the engine speed is controlled so as to coincide with the corrected engine target speed. When the engine output calculated by the engine output calculation means is lower than the engine target output calculated by the engine target output calculation means, the engine control means calculates the previous engine target rotation speed addition value from the engine target output. The difference engine speed corresponding to the value obtained by subtracting the engine output is cumulatively subtracted, and the cumulative engine subtracted engine target speed addition value is subtracted from the engine target speed, and the subtracted value is used as the corrected engine target speed. The engine control device according to any one of claims 1 to 3, wherein the engine speed is controlled so as to match the corrected engine target speed.   The engine control device according to any one of claims 1 to 4, wherein the engine control means performs control so that the corrected engine target speed is not reduced below the engine target speed.   The engine control means performs control not to update the target engine speed in a decreasing direction when the operation means is in a state of being increased from a neutral state toward a full state or being stationary after the increase. The engine control device according to any one of claims 1 to 5.   The engine control means performs control without correcting the target engine speed when the operation state of the operation means is in a neutral state or a fine operation state close to neutral. The engine control device according to any one of the above. A generator motor coupled to the output shaft of the engine;
A capacitor that accumulates the power generated by the generator motor and supplies the power to the generator motor;
Determining means for determining whether or not to cause the generator motor to perform engine torque assist;
With
The said engine control means performs control which does not correct | amend the said engine target rotation speed before, when the said determination means performs an engine torque assist effect | action. Engine control device. An operation state determination unit that determines that the operation unit is switched from a non-operation state to an operation state based on an operation amount of the operation unit;
A second target engine speed setting unit that sets the target engine speed of the engine to a second engine target engine speed that is higher than the low idle engine speed when it is determined that the operation state determination unit has switched to the operation state;
The engine control means controls the engine speed so that it matches the higher engine target speed of the corrected engine target speed and the second engine target speed. The engine control device according to any one of claims 1 to 8. Discriminating means for discriminating work patterns of a plurality of hydraulic actuators from the operation amount of each operating means and the load pressure of the hydraulic pump;
Horsepower limit value setting means for setting the horsepower limit value of the hydraulic pump according to each work pattern;
Third target speed setting means for setting a third engine target speed in accordance with the horsepower limit value of the hydraulic pump;
And the engine control means controls the engine speed so as to coincide with the smaller engine target speed among the corrected engine target speed and the third engine target speed. The engine control device according to any one of claims 1 to 9.

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