JP2005163605A - Drive controller of hybrid working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive controller of a hybrid working machine in which an operator can sense the variability in a working load, can obtain the working feeling to have priority over the great strong power for high load working, and over the speed for the light load working respectively, and stably can operate an engine even when the working load suddenly increases. <P>SOLUTION: Composite torque output characteristics to compose engine torque output characteristics of an engine 16 due to engine controllers (21 to 25), and powering/regenerating torque output characteristics of an electric motor/generator 20 due to electric motor/generator controllers(21, 38) increases the output torque with the increase in the working load, and is set to such characteristics that the real revolution speed of the engine 16. In the predetermined engine revolution speed, a matching point to balance the composite torque output characteristics with pump absorbing torque characteristics due to a pump absorbing torque controller 30 is set. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drive control device for a hybrid work machine that is suitable for application to a work machine such as a hydraulic excavator or a wheel loader.

  As this type of conventional drive control device, there are an electric motor / generator coupled to a hydraulic pump having an engine as a driving source, an electric storage means for transferring electric energy between the electric motor / generator, and a hydraulic operation unit. When the absorption torque detected by the absorption torque detection means is smaller than a predetermined torque set value, the absorption torque detection means for detecting the required absorption torque in the hydraulic pump required for driving the hydraulic pump is provided. It is known that the electric motor / generator is operated to generate electric power, and that the electric motor / generator is operated to perform power running (assist operation) when the absorption torque is larger than the torque setting value (for example, Patent Document 1).

  However, in this conventional apparatus, an absorption torque detecting means is required to detect the necessary absorption torque in the hydraulic pump that is necessary for driving the hydraulic operation unit, and the apparatus becomes complicated, and the hydraulic pressure from the engine is increased. There is a problem that it is not possible to accurately control the target optimum engine load characteristics because the influence of inertia load and frictional force in the power transmission path to the pump is not taken into consideration.

  Prior art that can solve such a problem is proposed in Patent Document 2. The drive control device according to this prior art connects an electric generator to an engine that is a driving source of a hydraulic pump that supplies pressure oil to a hydraulic operation unit so that torque can be transmitted, and the operation of the electric generator The motor / generator control means for controlling the engine speed is used, the engine speed corresponding to the target torque is used as the target value of the engine speed, and this target value is compared with the actual measured value of the engine speed. When the value becomes smaller than the value, the motor / generator control means causes the motor / generator to function as an electric motor, and when the measured value becomes larger than the target value, the electric motor / generator control means causes the electric motor / generator to function as a generator. It is configured as follows. According to this drive control device, the engine output can be controlled to maintain the target torque without directly detecting the engine shaft torque absorbed by the hydraulic pump. Since the actual measured value of the engine speed compared with the target value includes the influence of inertia load and frictional force in the power transmission path from the engine to the hydraulic pump, the engine output torque can be accurately controlled.

JP-A-9-224354 JP 2003-28071 A

  However, the prior art is a technique that compensates for the optimum engine load characteristic by powering / regenerative operation by an electric motor / generator. In the drive control device according to this prior art, even if the work load fluctuates, the actual rotation of the engine Since the engine speed is converged to the target engine speed and the fluctuation of the engine speed is not substantially allowed with respect to the fluctuation of the work load, the operator can change the work load based on the change in the engine speed. It is impossible to detect the degree of fluctuation of the movement, and there is a problem that it is not possible to accurately grasp the place of adjustment in proceeding with the work. Also, because the engine output torque point is kept at a single point, priority is given to strength for high-load work and speed for light-load work. There is a problem that it is not possible to realize a work feeling with a beam. In addition, there is a problem that the engine cannot be operated stably because the assist operation by the motor / generator cannot compensate for the sudden increase in work load.

  The present invention has been made in order to solve such problems. The operator can sense the degree of fluctuation of the work load, and can accurately grasp the place of adjustment in advancing the work. Work feeling that prioritizes strength for heavy work and speed for light work can be obtained, and the engine can be operated stably even if the work load increases rapidly. An object of the present invention is to provide a drive control device for a hybrid work machine.

To achieve the above object, a drive control device for a hybrid work machine according to the present invention comprises:
An electric motor / generator provided so as to be able to transmit torque between the engine, a hydraulic pump driven by the engine, a hydraulic operation unit operated by pressure oil discharged from the hydraulic pump, and the engine And a drive control device for a hybrid work machine including a power storage means for transferring electric energy to and from the motor / generator,
Engine absorption means for controlling the engine; Electric motor / generator control means for controlling the electric motor / generator; Pump absorption torque such that the absorption torque of the hydraulic pump increases or decreases as the actual rotational speed of the engine increases or decreases A pump absorption torque control means for controlling the hydraulic pump so as to have characteristics,
An engine torque output characteristic obtained by controlling the engine by the engine control means in an engine speed region between one engine speed on the high speed side and one engine speed on the low speed side of the engine; The combined torque output characteristics obtained by combining the power running / regenerative torque output characteristics obtained by the control of the electric motor / generator by the electric motor / generator control means increases the output torque as the work load increases. And setting a matching point that balances the combined torque output characteristic and the pump absorption torque characteristic at a predetermined engine speed in the engine speed range, while setting so as to reduce the speed. It is characterized (first invention).

  In the first aspect of the invention, the engine speed region between the predetermined engine speed and the one engine speed on the high speed side includes an engine speed for obtaining a minimum fuel consumption rate of the engine. Preferred (second invention).

  In the first invention or the second invention, it is preferable that an inertia load means is provided in a drive path for the hydraulic pump (third invention).

  According to the first invention, the engine torque obtained by controlling the engine by the engine control means in the engine speed region between one engine speed on the high speed side and one engine speed on the low speed side in the engine. The combined torque output characteristics that combine the output characteristics and the power running / regenerative torque output characteristics obtained by the motor / generator control by the motor / generator control means increase the output torque as the work load increases. Since the engine speed is set to decrease, the operator can detect the degree of change in the work load based on the increase / decrease change in the engine speed and accurately determine the place to adjust the work. It is possible to obtain a work feeling that prioritizes strength for high-load work and speed for light-load work. It is possible. Further, there is a matching point that balances the combined torque output characteristic with the pump absorption torque characteristic that increases or decreases the absorption torque of the hydraulic pump with the increase or decrease of the actual rotation speed of the engine at a predetermined engine rotation speed in the engine rotation speed region. Therefore, even if the output torque required by the work load exceeds the output torque corresponding to the matching point, the actual engine speed is converged to the predetermined engine speed. Therefore, even if the work load suddenly increases, the decrease in engine speed can be kept within a certain range with the predetermined engine speed as the lower limit without significantly increasing the output of the engine or motor / generator. The engine can be operated stably. In addition, by setting the change region of the engine speed accompanying the fluctuation of the work load corresponding to the engine torque output characteristic portion where the output torque gradient in the vicinity including the rated torque point is relatively gentle, for example, Leveling can be achieved and the engine can be operated efficiently. In addition, because the maximum output torque required for the engine is reduced by the amount of assist (powering operation) by the motor / generator, it is possible to reduce the size of the engine, fuel consumption, exhaust gas, noise, etc. In addition, the installation space can be reduced and the weight can be reduced.

  According to the second aspect of the invention, since the engine speed range between the predetermined engine speed and the one engine speed on the high speed side includes the engine speed for obtaining the minimum fuel consumption rate, The fuel consumption can be reduced more effectively.

  In addition, according to the third invention, since the inertia load means is provided in the drive path for the hydraulic pump, a drastic drop in the engine speed due to a sudden work load is suppressed, and the engine can be operated more stably. Can do.

  Next, a specific embodiment of a drive control device for a hybrid work machine according to the present invention will be described with reference to the drawings. The present embodiment is an example in which the drive control device of the present invention is applied to a hydraulic excavator as a work machine.

  FIG. 1 is a side view of a hybrid excavator according to an embodiment of the present invention. FIG. 2 shows a schematic system configuration diagram of a drive control device in the hybrid excavator of the present embodiment.

  As shown in FIG. 1, the hybrid excavator 1 of the present embodiment includes a lower traveling body 2 including a traveling device 2b driven by a traveling hydraulic motor 2a, and a swing driven by a swing hydraulic motor 3a. An upper revolving unit 4 disposed on the lower traveling body 2 via the revolving device 3, a work machine 5 attached to the front center position of the upper revolving unit 4, and its upper revolving The cab 6 is provided at the front left position of the body 4. The working machine 5 includes a boom 7, an arm 8, and a bucket 9 that are rotatably connected in order from the upper swing body 4, and a hydraulic cylinder that corresponds to each of the boom 7, arm 8, and bucket 9. (Boom cylinder 10, arm cylinder 11 and bucket cylinder 12) are arranged.

  As shown in FIG. 2, the drive control device 15 in the hybrid hydraulic excavator 1 includes an engine 16, a variable displacement hydraulic pump (hereinafter simply referred to as “hydraulic pump”) 17 driven by the engine 16, and The motor / generator 20 connected to the output shaft 18 of the engine 16 with respect to the hydraulic pump 17 via a power transmission mechanism 19, the engine 16, the motor / generator 20, a pump absorption torque control device 30 described later, and the like are controlled. The controller 21 is provided.

  The engine 16 is provided with a fuel injection pump 22 and a governor 23, and a fuel control lever 23 a of the governor 23 is driven by a governor drive motor 24. Further, the drive position of the fuel control lever 23 a is detected by a potentiometer 25, and the detection signal is input to the controller 21. Further, a fuel dial 26 is provided for setting the throttle amount of the engine 16, and a throttle signal from a potentiometer 26 a attached to the fuel dial 26 is input to the controller 21. The actual rotational speed of the output shaft 18 of the engine 16 is detected by a rotational speed sensor 27, and the detection signal is also input to the controller 21. Here, an electronically controlled injection device in which the governor device including the governor 23, the governor drive motor 24, etc. is an electronic governor, or an electronically controlled injection system mainly composed of a common rail fuel injection device may be employed. This makes it possible to perform drive control with higher accuracy and greater freedom.

In the engine control apparatus including the fuel injection pump 22, the governor 23, the governor drive motor 24, the potentiometer 25, and the controller 21, the controller 21 rotates with the throttle signal (target rotational speed signal) input by the fuel dial 26. Based on the deviation signal from the actual rotational speed signal of the engine 16 detected by the number sensor 27, a voltage that satisfies a predetermined functional relationship is generated as a drive signal, and the governor drive motor 24 is driven based on this drive signal. . Further, the governor 23 controls the output torque of the engine 16 so as to have a characteristic indicated by a symbol T [E] in FIGS. In the present embodiment, the fuel consumption map is set so that the fuel consumption rate of the engine 16 is minimized at the rated torque point G indicated by the coordinates (N _B , T _E1 ) in FIGS.

Now, as an example, when the fuel dial 26 is assumed to be set to the maximum position, the output signal from the potentiometer 26a indicates the maximum target engine speed N _{S (see} FIGS. 5-7) sized to be shown in FIG. 2 is set to, from the controller 21 the motor driving signal corresponding to the maximum target engine speed N _S is applied to the governor drive motor 24. Thus, the governor drive motor 24 operates the fuel control lever 23a so that the highest speed regulation line L _S (see FIGS. 5 to 7) is set, and the output horsepower and the engine speed of the engine 16 are automatically set. The

  The output shaft 18 of the engine 16 is provided with a flywheel 28 that functions as an inertial load, and the flywheel 28 bears one blade for stabilizing the engine speed. Instead of the inertia load means by the flywheel 28, the rotor of the motor / generator 20 may have a flywheel function.

  The pressure oil discharged from the hydraulic pump 17 is a pilot pressure operation type provided corresponding to each hydraulic actuator (travel hydraulic motor 2a, turning hydraulic motor 3a, boom cylinder 10, arm cylinder 11, bucket cylinder 12). It is supplied to the traveling hydraulic motor 2a, the turning hydraulic motor 3a, and various hydraulic cylinders (the boom cylinder 10, the arm cylinder 11, and the bucket cylinder 12) via a control valve 29 that is an assembly of direction switching valves (not shown). It has become so.

A pump absorption torque control device 30 is attached to the hydraulic pump 17. The pump absorption torque control device 30 includes a hydraulic circuit (not shown in detail) 32 that supplies pressure oil to a servo valve 31 that adjusts the tilt angle of the swash plate 17 a of the hydraulic pump 17. A pressure / flow compensator valve 33 for sensing the pressure and flow rate required by the motor, an electromagnetic proportional flow control valve 34 for determining the magnitude of the flow rate, and an electromagnetic proportional pressure control valve 35 for controlling the maximum pressure of the hydraulic pump 17 are provided. The following controls (A) to (C) are performed by command signals from the controller 21 to the control valves 34 and 35, respectively.
(A) The input torque to the hydraulic pump 17 is controlled to be constant and the maximum value of the input torque is adjusted.
(B) The hydraulic pump 17 discharges the pressure and flow rate required by the load [the load W related to the hydraulic operation unit (travel device 2b, turning device 3, work implement 5)].
(C) The hydraulic pump 17 is controlled such that the absorption torque of the hydraulic pump 17 (the input torque to the hydraulic pump 17) has a pump absorption torque characteristic that increases / decreases as the actual rotational speed of the engine 16 increases / decreases. . In other words, the maximum target engine speed of the engine 16: hydraulic pump in accordance with an increase / decrease of the deviation (speed setting this embodiment by the engine speed represented by the symbol N _S in Fig. 7) and the actual rotational speed 17 The hydraulic pump 17 is controlled so as to decrease / increase the absorption torque (refer to the pump absorption torque characteristic line indicated by the symbol PL ₁ in FIG. 6 and the pump absorption torque characteristic line indicated by the symbol PL ₂ in FIG. 7). .

  The motor / generator 20 serves as both a motor and a generator, and switches between a power running operation that assists the drive of the hydraulic pump 17 by the engine 16 and a regenerative operation that generates power using the engine 16 as a drive source. It is configured to be possible. The motor / generator 20 is connected to a power storage device 39 via an inverter 38, and the inverter 38 controls the power running operation and the regenerative operation of the motor / generator 20 in accordance with a command from the controller 21. doing. The motor / generator control device including the controller 21 and the inverter 38 corresponds to the “motor / generator control means” of the present invention.

  The power storage device (power storage means) 39 includes a power storage unit 40 including a secondary battery such as a nickel cadmium battery, a nickel metal hydride battery, or a lithium ion battery, or a capacitor. The power storage device 39 is provided with a voltage sensor 41, a current sensor 42, a temperature sensor 43, and the like, and detection signals from the sensors 41, 42, 43 are input to the controller 21. Based on information such as voltage, current, and temperature detected by the sensors 41, 42, and 43, the controller 21 manages the amount of stored electricity and controls charge and discharge.

In the cab 6, a work machine operation lever 44 for operating the turning operation of the upper turning body 4 and the bending and undulating operation of the work machine 5, and the running operation of the lower traveling body 2 arranged in the cab 6. A travel operation lever 45 to be operated is provided. The work machine operation lever 44 and the travel operation lever 45 are provided with pressure reducing valves 46 and 47, respectively, and pilot pressure oil corresponding to the operation of the operation levers 44 and 45 is discharged from the pressure reducing valves 46 and 47, respectively. It has come to be. The pilot pressure oil discharged from the pressure reducing valves 46 and 47 is input to a predetermined pilot pressure oil input port in the control valve 29 to perform a predetermined oil path switching operation. In this way, the turning operation of the upper swing body 4 and the bending and raising / lowering operation of the work machine 5 are performed by a predetermined operation of the work machine operation lever 44, and the lower travel is performed by a predetermined operation of the travel operation lever 45. The traveling operation of the body 2 is performed. In addition, operation signals indicating the operation states of the work machine operation lever 44 and the travel operation lever 45 are input to the controller 21 via hydraulic switches 48 and 49 attached to the pressure reducing valves 46 and 47, respectively. ing. In the present embodiment, there are eight types of operation signals to be input to the controller 21 by predetermined operations of the operation levers 44 and 45 as described below.
(1) Turning operation signal corresponding to the turning operation of the upper turning body 4 (2) Boom raising operation signal corresponding to the raising operation of the boom 7 (3) Boom lowering operation signal corresponding to the lowering operation of the boom 7 (4) Arm Arm dump operation signal corresponding to the operation of sending 8 forward (5) Arm excavation operation signal corresponding to the operation of pulling arm 8 forward (6) Bucket dump operation signal (7) corresponding to the operation of sending bucket 9 forward Bucket excavation operation signal corresponding to the operation of pulling the bucket 9 forward (8) Traveling operation signal corresponding to the traveling operation of the lower traveling body 2

  In place of the device configuration shown in FIG. 2 in which the hydraulic switches 48 and 49 are attached to the pressure reducing valves 46 and 47, as shown in FIG. 3 is a device configuration in which hydraulic switches 54 and 55 (or pressure sensors) are attached to the pilot pressure operating sections 52 and 53 provided corresponding to 51, respectively, or as shown in FIG. Even in an apparatus configuration in which potentiometers 56 and 57 for detecting the operation positions of the operation levers 44 and 45 are attached to the respective 46 and 47, the operation mode can be determined in the same manner as the operation mode determination means described later. is there.

  In the present embodiment, the controller 21 determines the operating state of the hydraulic operation unit (the traveling device 2b, the turning device 3, and the work implement 5) by turning ON / OFF the input of each operation signal to the controller 21. Based on the determination, an operation mode determination unit is configured to determine which operation mode is an idle mode, a travel mode, or a work mode, which will be described later.

  Further, in the present embodiment, as shown in Table 1, power running / regenerative torque output characteristics of the motor / generator 20 corresponding to each operation mode are set in advance, and each power running / regenerative torque output characteristic is set as follows. Power running / regenerative torque output value information (data tables A and B) obtained by relating to the rotational speed of the engine 16 is stored in the storage area of the controller 21.

  Then, the controller 21 selects a data table corresponding to the operation mode determined by the operation mode determination means, and the power running / regenerative torque value corresponding to the actual rotational speed of the engine 16 based on the selected data table. And the operation of the motor / generator 20 is controlled via the inverter 38 so that the motor / generator 20 outputs the calculated power running / regenerative torque value.

  Next, the procedure of operation mode discrimination by the operation mode discrimination means will be described below with reference to the flowchart shown in FIG. In the figure, symbols Q and R each represent a step. In addition, in the following description, the “work machine operation signal” is an operation that collectively refers to the above-described boom raising operation signal, boom lowering operation signal, arm dump operation signal, arm excavation operation signal, bucket dump operation signal, and bucket excavation operation signal. It is a signal.

  Q1: This is a step of determining whether or not the traveling operation of the lower traveling body 2 is performed. When a travel operation signal is input to the controller 21, it is determined in the next step Q2 that the travel mode is set. On the other hand, when the traveling operation signal is not input to the controller 21, the process proceeds to step R1 of another flow.

  R1: A step of determining whether or not the operation of the work implement 5 and / or the swing operation of the upper swing body 4 is performed. When a turning operation signal and / or a work implement operation signal is input to the controller 21, it is determined in the next step R2 that the operation mode is set. On the other hand, when neither the turning operation signal nor the work implement operation signal is input to the controller 21, it is determined in step R3 that the idling mode is set.

  Next, the operation of the drive control device 15 in each operation mode determined by the operation mode determination means will be described below with reference to Table 1 and FIGS.

(In idling mode: see Fig. 5)
When the operation mode determined by the operation mode determination unit is the idling mode, the controller 21 selects the data table A shown in Table 1 and based on the actual engine speed detected by the engine speed sensor 27. Then, the selected data table A is searched. Now, as an example, when the actual rotational speed of the engine 16 detected by the rotational speed sensor 27 is assumed to be N _B, the controller 21, the table search, the regeneration torque as regeneration torque value to be output to the motor-generator 20 A value T _G1 is calculated, and a drive signal based on the calculated regenerative torque value T _G1 is output to the inverter 38. As a result, the motor / generator 20 performs a power generation operation using the regenerative torque value _TG1 . Here, the regenerative torque value T _G1 is set to the regenerative torque value corresponding to the power generation operation to compensate for self-consumption amount of the electric-generator 20 with co-rotation of the engine 16 in the actual rotational speed N _B . Thus, the remaining charge in the power storage unit 40 is kept more stable. Here, the self-consumption power consumption is the power consumption generated according to the rotational speed due to rolling friction, copper loss, iron loss, circuit loss, etc. due to the motor / generator 20 traveling with the engine 16. That is.

(Driving mode: see Fig. 6)
When the operation mode determined by the operation mode determination means is the travel mode, the controller 21 selects the data table A shown in Table 1 and based on the actual engine speed detected by the engine speed sensor 27. Then, the selected data table A is searched. That is, in the traveling mode, as in the idling mode described above, a power generation operation that compensates for the self-power consumption of the motor / generator 20 accompanying the rotation with the engine 16 is performed. On the other hand, the pump absorption torque control unit 30, the maximum value of the input torque to the hydraulic pump 17, the maximum output point of the engine 16 to the target rotation speed N _S of the engine 16 is set by being set (actual rotational speed N _B ) is set to a value commensurate with the output torque value T _E1 (rated torque point G), and the pump absorption torque characteristic line indicated by symbol PL ₁ in the figure is set so that the maximum value of the input torque is T _E1 . Control its input torque along. In this way, by increasing the output (so-called “pump absorption horsepower”) that the hydraulic pump 17 absorbs from the engine 16, the intended operation of the traveling device 2 b can be achieved without the power running operation (assist operation) by the motor / generator 20. The output of the hydraulic pump 17 required to exhibit the operational performance is ensured. Here, even if a value corresponding to the output torque value near the output torque value T _E1 is adopted as the maximum value of the input torque, substantially the same effect can be obtained.

(In work mode: see Fig. 7)
When the operation mode determined by the operation mode determination means is the work mode, the controller 21 selects the data table B shown in Table 1 and based on the actual engine speed detected by the engine speed sensor 27. Then, the selected data table B is searched. Thereby, the power running / regenerative torque output characteristic Tb [M / G] as shown in FIG. 7 is set. As shown in the figure, an engine speed region (N _{H to} N _L) between one engine speed N _H on the high speed side and one engine speed N _L on the low speed side in the engine 16. ), An engine torque output characteristic T [E] obtained by controlling the engine 16 by the engine control device, and a power running / regenerative torque output characteristic Tb obtained by controlling the motor / generator 20 by the motor / generator control device. The combined torque output characteristic (Tb [M / G] + T [E]) combined with [M / G] reduces the actual engine speed of the engine 16 while increasing the output torque as the work load increases. while being set to a characteristic, the engine speed range _(N H ~N _L) combined torque output characteristic at a predetermined engine speed _{N M} of (Tb [M / G] + T E]) and the pump absorption torque control unit 30 matching point M to balance the pump absorption torque characteristic PL ₂ obtained by control of is set. In this embodiment, the one engine speed N _L on the low speed side is set to the engine speed corresponding to the maximum torque point of the engine 16. The predetermined engine rotational speed N _M is set to the engine speed corresponding to the maximum power (horsepower) points obtained by combining the torque output characteristic (Tb [M / G] + T [E]).

Now, as an example, when the actual rotational speed of the engine 16 detected by the rotational speed sensor 27 is assumed to be N _M, the controller 21, the table search, power torque value as the torque value to be output to the motor-generator 20 T _M1 is calculated, and a drive signal based on the calculated power running torque value T _M1 is output to the inverter 38. Thereby, the motor / generator 20 performs a power running operation that outputs a power running torque value T _M1 . For example, if the actual rotational speed of the engine 16 detected by the rotational speed sensor 27 is _NH , the controller 21 searches the table 21 for a regenerative torque value T as a torque value to be output to the motor / generator 20. _G2 is calculated, and a drive signal based on the calculated regenerative torque value _TG2 is output to the inverter 38. As a result, the motor / generator 20 performs a power generation operation using the regenerative torque value _TG2 . Further, the actual rotational speed _{N M} of the engine 16, the pump absorption torque control unit 30, the input torque to the hydraulic pump 17, a power running torque value _{T M1} of the output torque _{T E2} and the electric-power generator 20 of the engine 16 Control is performed so as to keep the input torque constant along the pump absorption torque characteristic PL ₂ so that the combined output torque value becomes (T _E2 + T _M1 ).

According to the present embodiment, in the work mode, the combined torque output characteristic (Tb [M / G] + T [T] obtained by combining the engine torque output characteristic T [E] and the power running / regenerative torque output characteristic Tb [M / G]. E]) is set so as to reduce the actual engine speed while increasing the output torque as the work load increases, so that the engine speed decreases as the work load increases or decreases. Will be. Therefore, the operator can sense the degree of fluctuation of the work load based on the increase / decrease change in the engine speed, and can accurately grasp the place to adjust the work, and is powerful for high load work. Furthermore, it is possible to obtain a work feeling in which speed is prioritized for light load work. Also, to balance the said engine speed range _(N L to N _H) Synthesis torque output characteristics at a predetermined engine speed _{N M} of (Tb [M / G] + T [E]) and a pump absorption torque characteristic PL ₂ Since the matching point M is set, even if the output torque required by the work load exceeds the output torque (T _E2 + T _M1 ) corresponding to the matching point M, the actual rotational speed of the engine 16 is the predetermined engine rotational speed. It will be converged to N _M. Therefore, even if the work load suddenly increases, fluctuations in the engine speed are kept within a certain range with the predetermined engine speed _NM as the lower limit without significantly increasing the output of the engine 16 or the motor / generator 20 ( N _M -N _H ), and the engine 16 can be operated stably. Further, the engine rotation speed change region (N _{H to} N _M ) with respect to the output torque fluctuation [0 to (T _E2 + T _M1 )] required by the work load is the output in the vicinity including the rated torque point G of the engine 16. Since the torque gradient is set corresponding to a relatively gentle engine torque output characteristic part (part surrounded by a broken line indicated by symbol Q in FIG. 7), the engine load can be leveled, The engine 16 can be operated efficiently. Further, a minimum fuel consumption rate of the engine 16 is obtained in an engine speed region (N _{M to} N _H ) between the predetermined engine speed N _M and the one engine speed N _H on the high speed side. because it contains the engine speed N _B, it is possible to reduce the fuel consumption of the engine 16 more effectively. In addition, since the maximum output torque required for the engine 16 is reduced by the assist (powering operation) by the motor / generator 20, the engine 16 can be reduced in size, and the fuel consumption and fuel consumption can be reduced. Exhaust gas, noise, and the like can be improved, and installation space can be reduced and weight can be reduced.

1 is a side view of a hybrid excavator according to an embodiment of the present invention. Schematic system configuration diagram of the drive control device in the hybrid excavator of this embodiment The figure showing the other example of an apparatus structure concerning an operation mode discrimination | determination means Flowchart explaining operation mode discrimination process Output torque characteristics diagram of engine and motor / generator in idling mode Output torque characteristics of engine and motor / generator in driving mode Output torque characteristics of engine and motor / generator in work mode

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hybrid hydraulic excavator 2a Traveling hydraulic motor 2b Traveling device 3 Turning device 3a Turning hydraulic motor 7 Boom 8 Arm 9 Bucket 10 Boom cylinder 11 Arm cylinder 12 Bucket cylinder 15 Drive control device 16 Engine 17 Hydraulic pump 20 Electric motor / generator 21 Controller 23 Governor 27 Speed sensor 28 Flywheel (Inertial load means)
30 Pump Absorption Torque Control Device 38 Inverter 39 Power Storage Device

Claims (3)

An electric motor / generator provided so as to be able to transmit torque between the engine, a hydraulic pump driven by the engine, a hydraulic operation unit operated by pressure oil discharged from the hydraulic pump, and the engine And a drive control device for a hybrid work machine including a power storage means for transferring electric energy to and from the motor / generator,
Engine absorption means for controlling the engine; Electric motor / generator control means for controlling the electric motor / generator; Pump absorption torque such that the absorption torque of the hydraulic pump increases or decreases as the actual rotational speed of the engine increases or decreases A pump absorption torque control means for controlling the hydraulic pump so as to have characteristics,
An engine torque output characteristic obtained by controlling the engine by the engine control means in an engine speed region between one engine speed on the high speed side and one engine speed on the low speed side of the engine; The combined torque output characteristics obtained by combining the power running / regenerative torque output characteristics obtained by the control of the electric motor / generator by the electric motor / generator control means increases the output torque as the work load increases. And setting a matching point that balances the combined torque output characteristic and the pump absorption torque characteristic at a predetermined engine speed in the engine speed range, while setting so as to reduce the speed. A drive control device for a hybrid work machine.   2. The hybrid according to claim 1, wherein an engine speed region between the predetermined engine speed and the one engine speed side on the high speed side includes an engine speed at which a minimum fuel consumption rate of the engine is obtained. Drive control device for work machines.   The drive control apparatus for a hybrid work machine according to claim 1, wherein an inertia load means is provided in a drive path for the hydraulic pump.

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