JP6077365B2 - Engine control device and hybrid construction machine equipped with the same - Google Patents

Description

  The present invention relates to an engine control apparatus for controlling an engine in a hybrid construction machine.

  The hybrid construction machine is an engine, a power storage device, a hydraulic pump that discharges hydraulic oil by power from the engine, and operates as a generator by power from the engine to charge the power storage device, while power from the power storage device is used. And a generator motor that operates as an electric motor and assists the engine.

  In this type of hybrid excavator, the discharge flow rate is controlled by adjusting the tilt of the hydraulic pump while the engine speed is kept constant, and the generator or motor is adjusted by adjusting the torque of the generator motor. It controls the operation of the generator motor as an electric motor.

  Here, the engine speed that is kept constant is set to a speed at which the fuel consumption rate becomes high when the engine load is relatively low, so that the fuel consumption rate is poor when the engine load is high. Become.

  Therefore, by reducing the engine speed when the engine load is lower than the normal load, while increasing the engine speed when the engine load is higher than the normal load, the fuel consumption rate is reduced. A technique for improving the performance is known (for example, Patent Document 1).

  Specifically, in the hybrid hydraulic excavator described in Patent Document 1, it is determined that the load is low during the boom lowering motion, and the engine speed is set to a predetermined low speed so that the engine can be operated under a high fuel consumption rate. Lower.

  It is also known to control the engine speed based on the state of charge (SOC) of the power storage device (for example, Patent Document 2).

  In the hybrid type work machine described in Patent Document 2, the engine required output for the (n + 1) period is calculated based on the load output of the work machine for the n period and the SOC of the power storage device at the end time of the n period. Based on this, a target value of the engine speed in the (n + 1) period is determined.

International Publication No. 2009/157511 JP 2011-47342 A

  However, in the technique described in Patent Document 1, although the engine speed is reduced to a predetermined low speed so that the engine can be operated under a high fuel consumption rate during the boom lowering operation, the predetermined low speed is determined. The method is not clear.

  Further, in the technique described in Patent Document 2, the engine speed is determined in anticipation of an engine demand output in the (n + 1) period in the future, but this speed is currently determined by a hydraulic pump, a generator motor, and an engine. The rotational speed is not set in consideration of the power required for the motor.

  Therefore, in each of Patent Documents 1 and 2, it is difficult to improve the fuel consumption rate while securing the required flow rate required for the hydraulic pump at the present time and the required driving horsepower required for the generator motor and the engine at the present time. is there.

  An object of the present invention is to provide an engine control device capable of improving a fuel consumption rate while securing a necessary flow rate and a required driving horsepower required at the present time, and a hybrid construction machine including the engine control device.

  In order to solve the above problems, the present invention provides an engine, a power storage device, at least one variable displacement hydraulic pump that discharges hydraulic oil by power from the engine, and a generator by power from the engine. A power generation motor that operates as an electric motor by the electric power from the power storage device to assist the engine, a hydraulic actuator that operates by discharge oil from the hydraulic pump, and the hydraulic actuator Operating means for operating the engine, operating amount detecting means for detecting the operating amount of the operating means, rotational speed setting means for setting the rotational speed of the engine, and the specified rotational speed set by the rotational speed setting means A controller for controlling the rotational speed of the engine so that the rotational speed of the engine is lower than Is defined by a rotational speed of the engine for obtaining a required flow rate of the hydraulic pump that is determined based on at least an operation amount of the operating means in a state where the rotational speed of the engine is the specified rotational speed. The engine capable of ensuring the minimum drive speed and the required drive horsepower determined by the operation amount of the operating means and the load state of the hydraulic pump in a state where the engine speed is the specified speed, and Among the second minimum rotation speeds defined by the engine rotation speed for obtaining the combined calculation force of the generator motor, the rotation speed is between the lower limit rotation speed selected higher and the specified rotation speed. Provided is an engine control device for a hybrid construction machine that outputs a command for controlling the engine speed.

  According to the present invention, between the first minimum rotation speed for obtaining the required flow rate of the hydraulic pump and the second minimum rotation speed for obtaining the required drive horsepower, the lower limit rotation speed selected at a higher level and the specified rotation speed The engine speed can be reduced so that the engine speed is between.

  Therefore, according to the present invention, the fuel consumption rate can be improved while ensuring the required flow rate and the required driving horsepower required at the present time.

  The engine control device further includes a cooling fan driven by power from the engine, and a temperature detector capable of detecting a temperature of a cooling system cooled by the cooling fan, wherein the controller includes the first lowest Based on the engine speed for cooling the temperature of the cooling system to a preset specified temperature based on the engine speed, the second minimum engine speed, and the temperature of the cooling system detected by the temperature detector. Of the third minimum rotational speeds defined, it is preferable to set a higher selected one as the lower limit rotational speed.

  In this aspect, in addition to the first minimum rotation speed and the second minimum rotation speed, the third minimum rotation speed for cooling the temperature of the cooling system to a preset specified temperature is also considered as an element for determining the lower limit rotation speed. Has been.

  Therefore, fuel consumption can be improved while ensuring the cooling capacity required at the present time.

  In the engine control apparatus, the controller is configured to output an output of the hydraulic pump, which is obtained from a target flow rate of the hydraulic pump set based on an operation amount of the operation means and a discharge pressure of the hydraulic pump. Preferably, the required flow rate is set as a flow rate in which the target flow rate is limited so that the output of the hydraulic pump does not exceed the output of the engine.

  According to this aspect, the flow rate determined by so-called constant horsepower control, which controls the flow rate of the hydraulic pump so that the output of the hydraulic pump does not exceed the output of the engine, can be used as the required flow rate. Thereby, it can suppress that an overload arises in an engine.

  In the engine control apparatus, it is preferable that the controller sets the first minimum rotational speed as the rotational speed of the engine for the hydraulic pump set to the maximum tilt to discharge the necessary flow rate.

  According to this aspect, it is possible to set the minimum first minimum rotational speed at which the necessary flow rate can be obtained.

  In the engine control device, the controller can set the required drive horsepower based on the required flow rate, a discharge pressure of the hydraulic pump, and the specified rotational speed.

  In the engine control device, the controller includes: an output characteristic of the engine with respect to the engine speed; an output characteristic of the generator motor with respect to the engine speed; and a charge amount of the generator motor determined by a charge amount of the power storage device. It is preferable to set a combined calculation force of the engine and the generator motor based on the upper limit value of the output.

  The output of the generator motor has an upper limit value corresponding to the charge amount of the power storage device. Therefore, the total calculation force of the engine and the generator motor can be set more accurately by taking into account the upper limit value of the output of the generator motor based on the charge amount of the power storage device as in the above aspect.

  In the engine control device, the controller stores in advance a map in which the third minimum rotational speed with respect to the temperature of the cooling system is set, and based on the temperature detected by the temperature detector and the map It is preferable to set the third minimum rotation speed.

  According to this aspect, since the third minimum rotation speed can be set based on a map stored in advance, the processing is performed more than when the third minimum rotation speed is set for each temperature detected by the temperature detector. It can be simplified.

  In the engine control device, the first hydraulic pump and the second hydraulic pump as the hydraulic pump, a merging line for merging the discharge oil of each hydraulic pump, and a flow of hydraulic oil through the merging line are allowed. A merging valve that is switchable between a permissible position that regulates and a regulation position that regulates the flow, and the controller includes the required flow rate of the first hydraulic pump and the required flow rate of the second hydraulic pump. Are different from each other, it is preferable to reduce the first minimum rotational speed by switching the merging valve to an allowable position and bringing the necessary flow rates close to each other so that a combined value of the necessary flow rates can be obtained.

  When the required flow rate of the first hydraulic pump and the required flow rate of the second hydraulic pump are different, the engine speed for obtaining the larger required flow rate is set as the first minimum rotational speed, so the hydraulic pump with a small required flow rate Is driven at a rotational speed higher than necessary.

  Therefore, the required flow rate per hydraulic pump can be reduced by bringing the required flow rates of the first hydraulic pump and the second hydraulic pump close to each other as in the above aspect, thereby reducing the first minimum rotational speed. can do.

  Further, the present invention provides a hybrid construction machine comprising: a machine body; a work attachment provided to be displaceable with respect to the machine body; and the engine control device including a hydraulic actuator for driving the work attachment. provide.

  According to the present invention, the fuel consumption rate can be improved while ensuring the required flow rate and the required driving horsepower required at the present time.

It is a side view showing the whole hybrid excavator composition concerning a 1st embodiment of the present invention. It is a circuit diagram which shows the engine control apparatus of the hybrid shovel shown in FIG. It is a flowchart which shows the outline | summary of the process performed by the controller shown in FIG. It is a graph for demonstrating the 2nd minimum rotation speed set by the controller shown in FIG. It is an example of the map which shows the relationship between the 3rd minimum rotation speed and the temperature of a cooling system. It is another example of the map which shows the relationship between the 3rd minimum rotation speed and the temperature of a cooling system. It is another example of the map which shows the relationship between the 3rd minimum rotation speed and the temperature of a cooling system. It is a circuit diagram which expands and shows a part of engine control apparatus which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. The following embodiments are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

<First Embodiment>
Referring to FIG. 1, a hybrid excavator 1 as an example of a hybrid construction machine includes a self-propelled lower traveling body (airframe) 2 and an upper revolving body (airframe) provided on the lower traveling body 2 so as to be able to swivel. 3, a work attachment 4 attached to the upper swing body 3, and an engine control device 5 shown in FIG. 2.

  The work attachment 4 includes a boom 6 that can be raised and lowered with respect to the upper swing body 3, an arm 7 that is swingably attached to the distal end portion of the boom 6, and a swing that moves relative to the distal end portion of the arm 7. And a bucket 8 movably attached.

  The work attachment 4 swings the boom 6 relative to the upper swing body 3, the arm cylinder 10 swings the arm 7 relative to the boom 6, and the bucket 8 swings relative to the arm 7. And a bucket cylinder 11 to be operated.

  Referring to FIG. 2, engine control device 5 includes an engine 12, a power storage device 19, a first hydraulic pump 14, a second hydraulic pump 15, a generator motor 18, and a cooling fan connected to the output shaft of engine 12. 23, a hydraulic actuator that is operated by hydraulic oil from each of the hydraulic pumps 14 and 15 (in FIG. 2, only the boom cylinder 9 and the arm cylinder 10 are illustrated, but the bucket cylinder 11 is also included), and the hydraulic oil for the hydraulic actuator Control valve 16 for controlling the supply and discharge of the motor, a remote control valve 17 as an operating means for operating the hydraulic actuator, a first inverter 20 for controlling the drive of the generator motor 18, and an upper turn with respect to the lower traveling body 2 A turning motor 21 for turning the body 3, a second inverter 22 for controlling the driving of the turning motor 21, and a cooling fan 23, a cooler 24 cooled by the engine 23, an accelerator 25 and a mode selector 26 as engine speed setting means for setting the engine speed of the engine 12, an ECU (Engine Control Unit) 27, And a controller 28 for outputting a command for controlling the number of rotations.

  The first hydraulic pump 14 and the second hydraulic pump 15 are variable displacement hydraulic pumps that discharge hydraulic fluid from the engine 12 by power. The discharge pressures from the hydraulic pumps 14 and 15 are detected by pressure detectors D1 and D2, respectively.

  The generator motor 18 operates as a generator by the power from the engine 12 to charge the power storage device 19. On the other hand, the generator motor 18 operates as a motor with the electric power from the power storage device 19 to assist the engine 12.

  Specifically, the first inverter 20 switches between the operation of the generator motor 18 as the generator and the operation as the motor. The first inverter 20 controls the current to the generator motor 18 or the torque of the generator motor 18. The first inverter 20 controls charging and discharging of the power storage device 19 according to the operating state of the generator motor 18.

  The remote control valve 17 generates a pilot pressure for the control valve 16 in response to the lever operation. The operation amount of the remote control valve 17 is detected as a pilot pressure by a pressure detector (operation amount detection means) D3. Here, although only one remote control valve 17 and pressure detector D3 are shown in FIG. 2, they are provided for each hydraulic actuator (each cylinder 9 to 10).

  The power storage device 19 is electrically connected to the first inverter 20 and the second inverter 22. The temperature of the power storage device 19 is detected by the temperature detector D4. The state of charge (charge amount) of the power storage device 19 is detected by a power storage state detector (temperature detector) D5.

  The second inverter 22 is between the state in which the upper swing body 3 is driven to rotate using the electric power of the power storage device 19 and the state in which the inertia energy at the time of the turn deceleration of the upper swing body 3 is regenerated to charge the power storage device 19. Thus, the drive of the turning motor 21 is controlled.

  The cooler 24 includes an oil cooler 29 that cools the hydraulic oil, a first radiator 30 that cools the cooling water of the engine 12, a second radiator 31 that cools the cooling water of the power storage device 19, and a supercharger of the engine 12. And an intercooler 32 for cooling the air used in the above.

  The temperature of the hydraulic oil before being cooled in the oil cooler 29 is detected by a temperature detector (temperature detector) D6. The temperature of the cooling water before being cooled in the first radiator 30 is detected by a temperature detector (temperature detector) D7. The temperature of the cooling water before being cooled in the second radiator 31 is detected by a temperature detector (temperature detector) D8. The temperature of the air before being cooled in the intercooler 32 is detected by a temperature detector (temperature detector) D9.

  The controller 28 outputs a command related to the rotational speed to the ECU 27 based on a command for the rotational speed of the engine 12 (hereinafter referred to as a prescribed rotational speed) set by the accelerator 25 and the mode selection means 26.

  Further, the controller 28 gives a command for controlling the rotational speed of the engine 12 so that the rotational speed of the engine 12 is lower than the specified rotational speed based on the detection results by the detectors D1 to D9 described above. Output.

  Specifically, the controller 28 secures the first minimum rotational speed defined by the rotational speed of the engine 12 and the necessary driving horsepower for the engine 12 and the generator motor 18 to obtain the required flow rates of the hydraulic pumps 14 and 15. Among the second minimum rotational speed defined by the rotational speed of the engine 12 and the third minimum rotational speed defined by the rotational speed of the engine 12 for adjusting the cooling capacity by the cooling fan 23 to a predetermined cooling capacity. A command for controlling the rotational speed of the engine 12 is output so that the rotational speed is between the lower limit rotational speed selected at a higher level and the specified rotational speed.

  Hereinafter, the processing of the controller 28 will be described with reference to FIG.

  The controller 28 determines the specified rotational speed based on the accelerator command and the mode selection command from the accelerator 25 and the mode selection means 26 (step S1).

  In step S1, the controller 28 stores in advance a map indicating the relationship between the accelerator command and mode selection command and the specified rotational speed, and sets the specified rotational speed based on this map and the accelerator command and mode selection command. Set.

  Next, the controller 28 determines the hydraulic pressure based on the specified rotational speed set in step S1, the lever operation command from the remote control valve 17 (pressure detector D3), and the pump discharge pressure from the pressure detectors D1 and D2. The required flow rates of the pumps 14 and 15 are calculated (step S2).

  In step S2, the controller 28 first determines each hydraulic pressure based on a map indicating the relationship between the lever operation command stored in advance and the target flow rate of each hydraulic pump 14, 15 and the input lever operation command. The target flow rates of the pumps 14 and 15 are set respectively. Here, the map shows the relationship between the lever operation command and the target flow rate in a state where the rotational speed of the engine 12 is the specified rotational speed. A large flow rate among the target flow rates of the hydraulic pumps 14 and 15 set in this way is used for the next processing.

  Specifically, the controller 28 outputs the hydraulic pumps 14 and 15 when the output of the hydraulic pumps 14 and 15 determined by the target flow rate and the pump discharge pressure set as described above exceeds the output of the engine 12. Therefore, the required flow rate is calculated by adding a limit (a constant horsepower control) to the target flow rate so that the output of the engine 12 does not exceed the output.

  Next, the controller 28 calculates the rotation speed (first minimum rotation speed) of the engine 12 for the hydraulic pumps 14 and 15 set to the maximum inclination to discharge the necessary flow rate (step S3). Specifically, the first minimum rotation speed is calculated by dividing the required flow rate by the capacity of the hydraulic pumps 14 and 15 set to the maximum tilt.

  Further, the controller 28 calculates the second minimum rotation speed based on the specified rotation speed, the required flow rate, the pump discharge pressure, and the state of charge of the power storage device 19 (step S4).

  In step S4, as shown in FIG. 4, the required drive horsepower H4 required for the engine 12 and the generator motor 18 is calculated at the specified rotational speed N1. Specifically, the controller 28 calculates the required drive horsepower H4 by multiplying the specified rotational speed, the required flow rate, and the pump discharge pressure.

  Next, the controller 28 calculates the second minimum rotational speed N2 for obtaining the combined calculation force H3 of the engine 12 and the generator motor 18 that can ensure the necessary drive horsepower H4.

  Specifically, the controller 28 calculates the combined calculation force of the engine 12 and the generator motor 18 based on the output characteristic H2 of the engine 12 with respect to the rotational speed of the engine 12 and the output characteristic H1 of the generator motor 18 with respect to the rotational speed of the engine 12. H3 is specified. Then, the controller 28 specifies the rotation speed of the engine 12, that is, the second minimum rotation speed N2 that can obtain the required driving horsepower H4 on the combined calculation force H3.

  The output of the generator motor 18 has an upper limit value corresponding to the amount of charge of the power storage device 19. Therefore, an upper limit value H1a is set in the output characteristic H1 of the generator motor 18 in accordance with the charge amount of the power storage device 19, and accordingly, the combined calculation force H3 also has a combined calculation force H3a in accordance with the charge amount of the power storage device 19. Is set. Thereby, the 2nd minimum rotation speed which can obtain required drive horsepower can be set correctly, without giving overload to power storage device 19.

  Next, the controller 28 calculates the third minimum rotational speed based on the cooling capacity based on the first cooling system temperature, the second cooling system temperature, the third cooling system temperature, and the temperature of the power storage device 19 (step S5). ).

  Here, the first cooling system temperature is the temperature of the hydraulic oil by the temperature detector D6, the second cooling system temperature is the temperature of the cooling water by the temperature detectors D7 and D8, and the third cooling system temperature is: It is the temperature of the air by the temperature detector D9. That is, a circuit through which hydraulic oil circulates, a circuit through which cooling water circulates (including power storage device 19 itself), and a circuit through which air circulates constitute a cooling system.

  As shown in FIG. 5, the controller 28 stores in advance a plurality of maps each indicating the relationship between the temperatures of the first to third cooling systems and the power storage device 19 and the third minimum rotation speed. In step S5, the controller 28 specifies a plurality of third minimum rotation speeds based on the maps and the detected temperatures of the detectors D6 to D9, and the largest of these third minimum rotation speeds. The rotation speed is set as the third minimum rotation speed used in the subsequent processing.

  In addition, in FIG. 5, the map which increases in steps according to the increase in detected temperature is illustrated, However, A map is not limited to this. For example, as shown in FIG. 6, it is possible to employ a map in which the third minimum rotation speed continuously increases as the temperature increases. Further, as shown in FIG. 7, it is possible to employ a map having hysteresis between when the temperature increases and when it decreases.

  Next, the controller 28 specifies the lower limit rotational speed that has been selected higher among the first to third minimum rotational speeds calculated in steps S3 to S5 (step S6).

  Then, the controller 28 determines the rotational speed to be commanded to the engine 12 (ECU 27) between the lower limit rotational speed and the specified rotational speed (step S7). In this step S7, it is possible to set the rotational speed having a margin with respect to the lower limit rotational speed in consideration of the response when returning to the specified rotational speed later. Further, the rotation speed can be set so as to avoid an area where the fuel efficiency characteristic is bad. Then, the controller 28 outputs the rotational speed command determined in step S <b> 7 to the ECU 27.

  Further, the controller 28 determines a tilt to be commanded to each of the hydraulic pumps 14 and 15 in order to obtain the necessary flow rate at the rotational speed determined in step S7 (step S8). Then, the controller 28 outputs the tilt command determined in step S8 to the regulators 14a and 15a (see FIG. 2) of the hydraulic pumps 14 and 15, respectively.

  Further, the controller 28 determines the distribution of the power of the power storage device 19 at the rotational speed determined in step S7, that is, the distribution of the operation of the generator motor 18 as the generator and the operation of the generator motor 18 as the motor. (Step S9). Then, based on the distribution determined in step S9, a torque command value to be commanded to the generator motor 18 (first inverter 20) is determined (step S10).

  Then, the controller 28 outputs the torque command value determined in each step S10 to the first inverter 20.

  As described above, according to the engine control device 5, the higher one of the first minimum rotational speed for obtaining the necessary flow rate of the hydraulic pumps 14, 15 and the second rotational speed for obtaining the required driving horsepower is selected. The engine 12 can be rotated so that the engine speed is between the lower limit engine speed and the specified engine speed.

  Therefore, the fuel consumption rate can be improved while ensuring the required flow rate and the required driving horsepower required at the present time.

  Moreover, according to 1st Embodiment, there exists the following effect.

  In the first embodiment, in addition to the first minimum rotational speed and the second minimum rotational speed, the third rotational speed for cooling the temperature of the cooling system to a preset specified temperature is also an element that determines the lower limit rotational speed. Has been taken into account.

  Therefore, fuel consumption can be improved while ensuring the cooling capacity required at the present time.

  According to the first embodiment, a flow rate determined by so-called constant horsepower control that controls the flow rate of the hydraulic pumps 14 and 15 so that the output of the hydraulic pumps 14 and 15 does not exceed the output of the engine 12 is used as the required flow rate. be able to. Thereby, it is possible to suppress the engine 12 from being overloaded.

  As in the first embodiment, the required flow rate is obtained by setting the first minimum rotational speed as the rotational speed of the engine 12 for the hydraulic pumps 14 and 15 set to the maximum tilt to discharge the required flow rate. It is possible to set a minimum first minimum rotation speed capable of

  According to the first embodiment, as shown in FIG. 4, the total calculation force of the engine 12 and the generator motor 18 is more accurately calculated by considering the upper limit value H1a of the output of the generator motor 18 based on the amount of power stored in the power storage device 19. Can be set.

  According to the first embodiment, since the third minimum rotation speed can be set based on the maps shown in FIGS. 5 to 7, the third minimum rotation speed for each temperature detected by the temperature detectors D <b> 6 to D <b> 9. The processing can be simplified as compared with the case of setting.

  However, based on the deviation between the temperature detected by the temperature detectors D6 to D9 and the upper limit temperature set for the cooler 24, the number of revolutions for making the temperature of the cooler 24 close to the upper limit temperature is calculated. Can be set to the third minimum rotational speed.

Second Embodiment
In the first embodiment, the first minimum number of revolutions is calculated based on the higher required flow rate of the required flow rates for the two hydraulic pumps 14 and 15, but the discharge oil of each hydraulic pump 14 and 15 is merged. Thus, the first minimum rotation speed can be reduced by lowering the required flow rate per hydraulic pump.

  Hereinafter, with reference to FIG. 8, the engine control apparatus 5 which concerns on 2nd Embodiment of this invention is demonstrated. In addition, illustration is abbreviate | omitted about one part of the structure similar to 1st Embodiment, the same code | symbol is attached | subjected about another part, and the description is abbreviate | omitted.

  The engine control apparatus 5 according to the second embodiment includes a merging line L1 for merging the discharge oils of the hydraulic pumps 14 and 15, a permissible position that allows the flow of hydraulic oil via the merging line L1, and the flow. An electromagnetic valve (junction valve) 33 that can be switched between a restriction position to be restricted is provided.

  The electromagnetic valve 33 is normally biased to the restriction position and is switched to the allowable position in response to a command from the controller 28.

  The controller 28 according to the second embodiment switches the solenoid valve 33 to an allowable position when the required flow rate of the first hydraulic pump 14 and the required flow rate of the second hydraulic pump 15 are different in step S2 shown in FIG. At the same time, the respective required flow rates are brought close to each other so that a total value of the required flow rates of the respective hydraulic pumps 14, 15 is obtained.

  As a result, the value of the maximum required flow rate (required flow rate per hydraulic pump) among the respective required flow rates can be reduced, thereby reducing the first minimum rotational speed calculated in step S2. Can do.

D3 Pressure detector (an example of operation amount detection means)
D4, D6 to D9 Temperature detector H1 Output motor output characteristics H1a Generator motor output upper limit value H2 Engine output characteristics H3, H3a Combined calculation force H4 Required drive horsepower L1 Junction line N1 Specified speed N2 Second minimum speed 1 Hybrid excavator (an example of construction machinery)
2 Lower traveling body (an example of the aircraft)
3 Upper revolving structure (an example of the aircraft)
4 Work attachment 5 Engine control device 9 Boom cylinder (an example of hydraulic actuator)
10 Arm cylinder (example of hydraulic actuator)
11 Bucket cylinder (example of hydraulic actuator)
12 Engine 14 First hydraulic pump 15 Second hydraulic pump 17 Remote control valve (operating means)
18 generator motor 19 power storage device 23 cooling fan 24 cooler (part of cooling system)
25 Accelerator (speed setting means)
26 Mode selection means (rotation speed setting means)
28 Controller 33 Solenoid valve (joint valve)

Claims (9)

Engine,
A power storage device;
At least one variable displacement hydraulic pump that discharges hydraulic oil by power from the engine;
A generator motor that operates as a generator by power from the engine to charge the power storage device, and operates as a motor by power from the power storage device to assist the engine;
A hydraulic actuator that operates by oil discharged from the hydraulic pump;
Operating means for operating the hydraulic actuator;
An operation amount detection means for detecting an operation amount of the operation means;
A rotation speed setting means for setting the rotation speed of the engine;
A controller for controlling the rotational speed of the engine so that the rotational speed of the engine is lower than a specified rotational speed set by the rotational speed setting means;
The controller is defined by the engine speed for obtaining a required flow rate of the hydraulic pump that is determined based on at least an operation amount of the operation means in a state where the engine speed is the specified rotation speed. And the required driving horsepower determined by the operation amount of the operating means and the load state of the hydraulic pump in a state where the engine speed is the specified engine speed. Among the second minimum rotation speeds defined by the engine rotation speed for obtaining the combined calculation force of the engine and the generator motor, the rotation speed is between the lower limit rotation speed selected at a higher level and the specified rotation speed. An engine control device for a hybrid construction machine that outputs a command for controlling the engine speed as described above. A cooling fan driven by power from the engine;
A temperature detector capable of detecting the temperature of the cooling system cooled by the cooling fan,
The controller cools the temperature of the cooling system to a preset specified temperature based on the first minimum speed, the second minimum speed, and the temperature of the cooling system detected by the temperature detector. 2. The engine control device for a hybrid construction machine according to claim 1, wherein, among the third lowest rotation speeds defined by the rotation speed of the engine for performing, the one selected higher is set as the lower limit rotation speed.   When the output of the hydraulic pump obtained by the target flow rate of the hydraulic pump and the discharge pressure of the hydraulic pump set based on the operation amount of the operation means exceeds the output of the engine, the controller The engine control device for a hybrid construction machine according to claim 1 or 2, wherein the required flow rate is set as a flow rate in which the target flow rate is limited so that the output of the hydraulic pump does not exceed the output of the engine.   4. The controller according to claim 1, wherein the controller sets the first minimum rotational speed as a rotational speed of the engine for discharging the necessary flow rate by the hydraulic pump set to maximum tilt. 5. The engine control device of the hybrid construction machine described in 1.   5. The hybrid construction machine according to claim 1, wherein the controller sets the required driving horsepower based on the required flow rate, a discharge pressure of the hydraulic pump, and the specified rotational speed. Engine control device.   The controller includes an output characteristic of the engine with respect to the rotational speed of the engine, an output characteristic of the generator motor with respect to the rotational speed of the engine, and an upper limit value of the output of the generator motor determined by a charge amount of the power storage device. The engine control apparatus for a hybrid construction machine according to any one of claims 1 to 5, wherein a combined calculation force of the engine and the generator motor is set based on the engine.   The controller stores in advance a map in which the third minimum rotation speed with respect to the temperature of the cooling system is set, and the third minimum rotation speed based on the temperature detected by the temperature detector and the map. The engine control device for a hybrid construction machine according to claim 2, wherein: A first hydraulic pump and a second hydraulic pump as the hydraulic pump;
A merging line for merging the oil discharged from each of the hydraulic pumps;
A merging valve that is switchable between a permissible position that allows the flow of hydraulic oil through the merging line and a regulating position that regulates the flow;
When the required flow rate of the first hydraulic pump and the required flow rate of the second hydraulic pump are different, the controller switches the merging valve to an allowable position and obtains a total value of the required flow rates. The engine control device for a hybrid construction machine according to any one of claims 1 to 7, wherein the first minimum rotational speed is reduced by bringing the necessary flow rates closer to each other. The aircraft,
A work attachment provided to be displaceable with respect to the airframe;
A hybrid construction machine comprising: the engine control device according to any one of claims 1 to 8 including a hydraulic actuator for driving the work attachment.

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