JP2005307785A - Drive control device for hybrid construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fuel economy and output performance of an engine. <P>SOLUTION: A drive control device for a hybrid construction machine has a controller 24. The controller 24 automatically shifts between the operation of an electric motor/generator 22 to function as a generator by excessive torque of the engine when absorption torque T1 detected by an absorption torque detection means 33 is smaller than a predetermined set value Ts, and the operation of the electric motor/generator 22 to function as an electric motor for torque assist when the absorption torque T1 is the predetermined set value Ts or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a drive control device for construction machines such as a hydraulic excavator, and in particular, can be driven by two drive systems: a drive using a hydraulic pump driven by an engine and a drive using a motor as a drive source. The present invention relates to a drive control device for a hybrid construction machine.

  In recent years, various construction machines having improved work environments such as exhaust gas and noise have been proposed. For example, a hybrid construction machine is known in which a generator is driven by an engine, an electric motor is driven by electric power generated by the generator, and a hydraulic pump is driven by the electric motor. There is known a hybrid construction machine that stores surplus power in a battery and drives an electric motor as necessary with the stored battery power (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-11888 (pages 2 to 5, FIGS. 2 and 3).

  In the invention described in Patent Document 1, since the hydraulic pump is not directly driven by the engine, the load associated with the work does not directly become the engine load, and the engine load can be kept constant. Although it can be operated with efficiency, there has been a problem that an electric motor for driving the hydraulic pump requires a large output and a generator needs a relatively large one.

  Therefore, there is a technical problem to be solved in order to make the structure capable of improving the fuel consumption and output performance of the engine without making the generator and the motor unnecessarily large. It aims at solving.

  The present invention has been proposed to achieve the above object, and the invention according to claim 1 is an engine, a hydraulic pump driven by the engine, a power storage device for storing power, and an operation as a generator. An electric motor / generator capable of selectively operating as an electric motor, a hydraulic actuator driven by the hydraulic pump to operate a hydraulic working unit, and an electric working unit driven by electric power of the power storage device In a drive control device for a hybrid construction machine having an electric working unit actuator that operates, an absorption torque detecting means for detecting an absorption torque of the hydraulic pump, and an absorption torque detected by the absorption torque detecting means are predetermined. When the set value is smaller than the set value, the motor / generator is operated as the generator with surplus torque of the engine, and the absorption torque is set to a predetermined value. When the above automatic switch control means to actuate the motor / generator as a motor for the torque assist to provide a drive control apparatus for a hybrid construction machine which includes a city.

  According to this configuration, when the absorption torque of the hydraulic pump detected by the absorption torque detection unit is smaller than a predetermined set value, the control unit automatically switches the electric / generator to the generator mode and automatically changes the engine. The electric / generator is rotated with the surplus torque, and the electric energy generated by the rotation is stored in the power storage device as electric power. On the contrary, when the absorption torque is larger than a predetermined set value, the motor / generator is automatically switched to the motor mode, and the motor / generator is driven to rotate as the motor with the electric power stored in the power storage device, The engine is assisted with this rotational driving force.

  According to the first aspect of the present invention, when the absorption torque of the hydraulic pump is larger than a preset value, the motor / generator is operated as a torque assisting motor to assist the engine, so that the engine load is reduced. This can improve fuel efficiency. Further, by assisting the engine, the engine can perform work exceeding the maximum output, so that the engine can be made smaller. Further, since the control means automatically performs the switching operation, the switching operation can be performed easily and appropriately.

  In order to achieve the purpose of improving the fuel consumption and output performance of the engine, the generator / generator is driven by the surplus torque of the engine when the absorption torque detected by the absorption torque detecting means is smaller than a preset value. And a drive control device for a hybrid construction machine provided with a controller that automatically switches the motor / generator to operate as a torque assisting motor when the absorption torque is greater than a predetermined set value.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a hydraulic excavator as a construction machine to which the present invention is applied. In the hydraulic excavator 10, an upper swing body 13 is rotatably mounted on a lower traveling body 11 via a swing mechanism 12. The upper swing body 13 is provided with a cab 14 on one front side thereof, and a boom 15 is attached to the front center portion so as to be able to be raised and lowered. An arm 16 is attached to the tip of the boom 15 so as to be rotatable up and down, and a bucket 17 is attached to the tip of the arm 16.

  FIG. 2 is a block circuit diagram showing a schematic configuration of a drive control apparatus related to the hydraulic excavator shown in FIG. In FIG. 2, the drive control apparatus according to the present embodiment includes an engine 21 for driving the hydraulic excavator 10, an electric / generator 22 and a hydraulic pump 23 connected to the power line of the engine 21, and control means. Controller 24, power storage device 25, electric motor 26 as an electric actuator that is driven by electric power stored in power storage device 25 and drives an electric working part of a hydraulic excavator, and electric power between electric motor 26 and power storage device 25 Discharged from an inverter 27 as an electric motor control unit that performs transfer control, an inverter 28 as an electric / generator control unit that controls electric power transfer between the electric / generator 22 and the power storage device 25, and the hydraulic pump 23. A control valve 30 for controlling the discharge flow rate of the pressure oil and a hydraulic working part of the excavator driven by the pressure oil from the hydraulic pump 23 are formed. An actuator 31 for hydraulic working portion which includes an absorption torque detection means 33 for detecting the absorption torque of the hydraulic pump 23.

  The engine 21 is a diesel engine in this embodiment. The electric / generator 22 receives a function as a generator that converts mechanical energy rotated by the engine 21 into electric energy and stores the electric energy in the power storage device 25, and the electric energy from the power storage device 25. It has a function as an electric motor that rotates by energy and converts to mechanical energy and assists the engine 21 by this rotation, and the electric motor and the generator are housed in one housing.

  The controller 24 is a microcomputer (commonly referred to as “microcomputer”), and controls the operation of the entire apparatus according to a predetermined procedure. For example, depending on the absorption torque state of the hydraulic pump 23 detected by the absorption torque detection means 33, It is determined whether to operate the motor / generator 22 as an electric motor mode that functions as an assisting motor or as a generator mode that functions as a generator, and outputs a switching command to the inverter 28.

  The drive control apparatus configured as described above is controlled by the controller 24 as a whole. The hydraulic actuator 31 is driven by the pressure oil from the hydraulic pump 23 to operate the hydraulic working unit. On the other hand, the electric motor 26 that is an actuator for the electric working unit is driven by electric power (electric energy) stored in the power storage device 25 to operate the electric working unit.

  FIG. 3 is a flowchart showing an example of a control procedure programmed in the controller 24. Next, the operation of the drive control apparatus shown in FIG. 2 will be described using the flowchart of FIG.

  Information about the absorption torque T1 of the hydraulic pump 23 is sequentially input from the absorption torque detection means 33 to the controller 24. In step S1, when the absorption torque T1 is smaller than a predetermined set value Ts, the process proceeds to step S2. In step S <b> 2, the electric / generator 22 is switched to the generator mode via the inverter 28, the electric / generator 22 is rotationally driven by the surplus torque of the engine 21, and the electric energy generated here is transferred to the power storage device 25. Store as electricity.

  On the other hand, when the absorption torque T1 is equal to or greater than the predetermined set value Ts, the process proceeds to step S3, and the motor / generator 22 is switched to the motor mode via the inverter 28. Then, the electric motor / generator 22 is rotationally driven by the electric power stored in the power storage device 25 as an electric motor, and the engine 21 is assisted by the rotational driving force of the electric motor / generator 22. Further, from step S2 and step S3, the process returns to step S1 to repeat the same processing operation.

  Therefore, according to the drive control apparatus in the present embodiment, when the absorption torque T1 of the hydraulic pump 23 is smaller than the predetermined set value Ts and a large load is not applied to the engine 21, the electric / generator When the motor / generator 22 is rotated by the surplus torque of the engine 21 to cause the power storage device 25 to be charged and the absorption torque T1 is equal to or greater than a predetermined set value Ts, the motor / generator 22 is set. Since the motor / generator 22 is rotationally driven by the electric power stored in the power storage device 25 and the engine 21 is assisted by this rotational drive, the load on the engine 21 is reduced. This can improve fuel efficiency. Further, by assisting the engine 21, the engine 21 can perform a work exceeding the maximum output, so that the engine can be made small. Further, since the controller 24 automatically performs the switching operation according to a preset procedure, the switching operation can be performed easily and appropriately.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is an overall configuration diagram of a hydraulic excavator to which a drive control device for a construction machine according to the present invention is applied. The block circuit diagram which shows schematic structure of the drive control apparatus in a hydraulic excavator same as the above. The flowchart which shows an example of the control procedure in the control means of a drive control apparatus same as the above.

Explanation of symbols

21 Engine 22 Electric motor / generator 23 Hydraulic pump 24 Controller (control means)
25 Power Storage Device 26 Electric Motor (Electric Actuator)
27 Inverter (motor controller)
28 Inverter (motor / generator controller)
30 Control valve 31 Actuator (hydraulic actuator)
33 Absorption torque detection means

Claims (1)

An engine, a hydraulic pump driven by the engine, a power storage device for storing power, an electric / generator capable of selectively performing an operation as a generator and an operation as an electric motor, and driving by the hydraulic pump In a drive control device for a hybrid construction machine, comprising: a hydraulic actuator that operates the hydraulic working unit; and an electric actuator that operates with the electric power of the power storage device to operate the electric working unit.
Absorption torque detecting means for detecting absorption torque of the hydraulic pump;
When the absorption torque detected by the absorption torque detecting means is smaller than a predetermined set value, the motor / generator is operated as the generator with surplus torque of the engine, and the absorption torque is set to a predetermined set value. Control means for automatically switching the motor / generator to operate as the torque assist motor at the above time,
And a drive control apparatus for a hybrid construction machine.

Images