JP5340627B2 - Hybrid construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide hybrid type construction equipment which can optimize power distribution to each section, in such a manner that an engine and a battery as power sources can be used in proper output ranges. <P>SOLUTION: Hybrid construction equipment comprises an oil pressure generating machine 14, a motor generator 12 connected with an engine 11 and functions as both a motor and a generator, an energy storage device 19, an electric drive section 21 which can generate regenerative power, and a control section 30 for controlling operation of the motor generator 12. The control section 30 calculates a first amount of assist power requested from a hydraulic drive section, a second amount of assist power requested from an electric load, and a third amount of assist power request for maintaining the charging rate of the energy storage device 19; determines the priority of first, second and third amounts of assist power request; and then determines the output value of the motor generator 12, based on the determination results. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

    The present invention relates to a construction machine, and more particularly to a hybrid construction machine that performs work efficiently by using two power sources in combination.

  Hybrid work machines that operate efficiently by combining the power of an internal combustion engine and the power of an electric motor have been developed and used. 2. Description of the Related Art As a hybrid work machine, one that takes a so-called parallel drive form is known.

  In the parallel drive mode, a hydraulic pump and a power machine that performs a generator action and a motor action are connected in parallel to an internal combustion engine (engine) as a common power source. The hydraulic actuator is driven by the hydraulic pump, and the power storage device is charged by the generator action of the power machine. The power is operated from the power storage device as an electric motor to assist the engine. In addition, as a motive power machine, there are a case where a dual-purpose machine (generator / motor) that performs both a generator action and a motor action is used, and a case where a separate generator and motor are used together.

  According to such a hybrid work machine, energy saving can be realized by reducing the load on the engine and operating the engine in a high efficiency range. However, the conventional hybrid work machine has the following problems.

  The charge / discharge characteristics of power storage devices such as batteries (secondary batteries) such as lithium ion capacitors and capacitors (electric double layer capacitors) depend on the amount of charge, and the lower the amount of charge, the greater the maximum charging power. The discharge power is reduced. Therefore, since the power distribution between the engine and the power storage device is determined regardless of the charge amount of such a power storage device, the charge amount of the power storage device is too small or too large depending on the load condition. As a result, the capacity of the power storage device cannot be used effectively, and the power storage device may be deteriorated.

  Therefore, in order to solve such problems, a power source device for a work machine that can determine the power distribution between the engine and the power machine according to the charge amount of the power storage device and keep the charge amount of the power storage device within an appropriate range is proposed. In this power source device, a hydraulic pump and a generator / motor are connected in parallel to an engine as a common power source, and power is stored by the generator action of the generator / motor. Charge the battery as a device. Further, the generator / motor is driven by the discharging force of the battery to perform the motor operation. Based on the required power of the actuator, the charging power and discharging power of the battery set according to the battery charging amount so that the battery charging amount is kept within a certain range, and the engine power set, Determine the power distribution of the generator / motor.

In addition, a method of determining a specific operation mode based on the operation state of the hydraulic operation unit and controlling the output of a generator / motor (referred to as an assist motor) has been proposed (for example, see Patent Document 2). ). According to this method, the input maximum value of the hydraulic pump is set to a predetermined value according to a specific operation mode, and the assist motor regenerates torque according to the deviation between the output torque value of the engine and the input maximum value of the hydraulic pump. Is controlled to output.
JP 2005-237178 A JP 2005-81973 A

  In the technique disclosed in Patent Document 1 described above, since the electric load required by the components of the construction machine is not taken into consideration, the regenerative power that can be generated by the electric load cannot be generated effectively. In addition, when a part of the drive mechanism is electrified and driven by electric power from the battery, the output of the motor is not taken into account, so that the state of charge (SOC) of the battery can be maintained in an appropriate range. There is a risk that it will not be possible. Furthermore, since the engine output limit is not provided, the engine load cannot be properly controlled, and the engine may be overloaded, causing engine stall and continuous operation.

  Further, in the technique disclosed in Patent Document 2 described above, it is necessary to prepare in advance table information in which output value information is input for each of various operation modes. Therefore, in order to prepare the table information, it is necessary to determine the optimum power distribution while reflecting the output of each drive unit corresponding to various operation modes and reflect it in the table. Don't be.

  The present invention has been made in view of the above-described problems, and is a hybrid construction that can optimize power distribution to each part so that an engine and a battery that are power sources can be used in an appropriate output range. The purpose is to provide a machine.

According to the present invention, a hydraulic pressure generator that converts engine output into hydraulic pressure and supplies the hydraulic drive unit, a motor generator that is connected to the engine and functions as both a motor and a generator, and the motor generator An electric storage unit that supplies electric power to function as an electric motor, and an electric drive unit that is driven by electric power from the electric storage unit and the motor generator and generates regenerative power to supply to at least one of the electric storage unit and the motor generator A hybrid construction machine having a control unit for controlling the operation of the motor generator, wherein the control unit calculates a second requested amount of assist power required by the hydraulic drive unit, and an electric load is required. The first assist power request amount is calculated, the third assist power request amount for maintaining the charging rate of the battery is calculated, and the first, second, and third assist power request amounts are prioritized. A hybrid construction machine is provided, wherein the rank is determined and the output value of the motor generator is determined based on the determination result.

  According to the present invention, appropriate power distribution can be performed according to the characteristics of the hydraulic drive unit and the electric drive unit. Also, the driving priority of the hydraulic drive unit and the electric drive unit can be appropriately adjusted according to their functions.

  Next, embodiments of the present invention will be described with reference to the drawings.

  First, a hybrid excavator will be described as an example of a hybrid construction machine to which the present invention is applied.

  FIG. 1 is a side view of a hybrid excavator. An upper swing body 3 is mounted on the lower traveling body 1 of the excavator via a swing mechanism 2. A boom 4 extends from the upper swing body 3, and an arm 5 is connected to the tip of the boom 4. Further, the bucket 6 is connected to the tip of the arm 5. The boom 4, the arm 5, and the bucket 6 are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, respectively. The upper swing body 3 is mounted with a cabin 10 and a power source (not shown).

  FIG. 2 is a block diagram showing the configuration of the drive system of the excavator shown in FIG. In FIG. 2, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a solid line, the pilot line is indicated by a broken line, and the electric drive / control system is indicated by a one-dot chain line.

  An engine 11 as a mechanical drive unit and a motor generator 12 as an assist drive unit are both connected to an input shaft of a speed reducer 13 as a booster. A main pump 14 and a pilot pump 15 are connected to the output shaft of the speed reducer 13. A control valve 17 is connected to the main pump 14 via a high pressure hydraulic line 16.

  The control valve 17 is a control device that controls the hydraulic system. Connected to the control valve 17 are hydraulic motors 1A (for right) and 1B (for left), a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9 for the lower traveling body 1 via a high-pressure hydraulic line.

  A battery 19 as a battery is connected to the motor generator 12 via an inverter 18. A turning motor 21 is connected to the battery 19 via an inverter 20. The turning electric motor 21 is an electric load in the excavator. A resolver 22, a mechanical brake 23, and a turning speed reducer 24 are connected to the rotating shaft 21 </ b> A of the turning electric motor 21. An operation device 26 is connected to the pilot pump 15 via a pilot line 25. A control valve 17 and a pressure sensor 29 as a lever operation detection unit are connected to the operating device 26 via hydraulic lines 27 and 28, respectively. The pressure sensor 29 is connected to a controller 30 that performs electric system drive control.

  The excavator having the above configuration is a hybrid construction machine that uses the engine 11, the motor generator 12, and the turning electric motor 21 as power sources. These power sources are mounted on the upper swing body 3 shown in FIG. Hereinafter, each part will be described.

  The engine 11 is an internal combustion engine composed of, for example, a diesel engine, and its output shaft is connected to one input shaft of the speed reducer 13. The engine 11 is always operated during the operation of the construction machine.

  The motor generator 12 may be an electric motor capable of both electric (assist) operation and power generation operation. Here, a motor generator that is AC driven by an inverter 20 is shown as the motor generator 12. The motor generator 12 can be constituted by, for example, an IPM (Interior Permanent Magnetic) motor in which a magnet is embedded in a rotor. The rotating shaft of the motor generator 12 is connected to the other input shaft of the speed reducer 13.

  The speed reducer 13 has two input shafts and one output shaft. The drive shaft of the engine 11 and the drive shaft of the motor generator 12 are connected to the two input shafts, respectively. Further, the drive shaft of the main pump 14 is connected to the output shaft. When the load on the engine 11 is large, the motor generator 12 performs an electric driving (assist) operation, and the driving force of the motor generator 12 is transmitted to the main pump 14 via the output shaft of the speed reducer 13. Thereby, driving of the engine 11 is assisted. On the other hand, when the load of the engine 11 is small, the driving force of the engine 11 is transmitted to the motor generator 12 through the speed reducer 13, so that the motor generator 12 generates power by the power generation operation. Switching between the electric (assist) operation and the power generation operation of the motor generator 12 is performed by the controller 30 according to the load of the engine 11 and the like.

  The main pump 14 is a hydraulic pump that generates hydraulic pressure to be supplied to the control valve 17. The hydraulic pressure generated by the main pump 14 is supplied to drive each of the hydraulic motors 1 </ b> A and 1 </ b> B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 that are hydraulic loads via the control valve 17. The pilot pump 15 is a pump that generates a pilot pressure necessary for the hydraulic operation system.

  The control valve 17 inputs the hydraulic pressure supplied to each of the hydraulic motors 1A, 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 for the lower traveling body 1 connected via a high-pressure hydraulic line. It is a hydraulic control device which controls these hydraulically by controlling according to the above.

  The inverter 18 is provided between the motor generator 12 and the battery 19 as described above, and controls the operation of the motor generator 12 based on a command from the controller 30. As a result, when the inverter 18 is operating and controlling the motor (assist) of the motor generator 12, necessary power is supplied from the battery 19 to the motor generator 12. Further, when the operation of the power generation of the motor generator 12 is controlled, the battery 19 is charged with the power generated by the motor generator 12.

  A battery 19, which is a storage battery, is disposed between the inverter 18 and the inverter 20. Thus, when at least one of the motor generator 12 and the turning electric motor 21 is performing an electric (assist) operation or a power running operation, the electric power necessary for the electric (assist) operation or the power running operation is supplied. In addition, when at least one of the power generation operation or the regenerative operation is performed, the power source is a power source for storing the electric power generated by the power generation operation or the regenerative operation as electric energy.

  The inverter 20 is provided between the turning electric motor 21 and the battery 19 as described above, and performs operation control on the turning electric motor 21 based on a command from the controller 30. Thus, when the turning electric motor 21 is in a power running operation, necessary electric power is supplied from the battery 19 to the turning electric motor 21. Further, when the turning electric motor 21 is performing a regenerative operation, the battery 19 is charged with the electric power generated by the turning electric motor 21.

  The turning electric motor 21 may be an electric motor capable of both power running operation and regenerative operation, and is provided for driving the turning mechanism 2 of the upper turning body 3. In the power running operation, the rotational force of the rotational driving force of the turning electric motor 21 is amplified by the speed reducer 24, and the upper turning body 3 rotates while being controlled for acceleration and deceleration. Further, due to the inertial rotation of the upper swing body 3, the number of rotations is increased by the speed reducer 24 and transmitted to the turning electric motor 21, and regenerative power can be generated. Here, as the turning electric motor 21, an electric motor driven by an inverter 20 by a PWM (Pulse Width Modulation) control signal is shown. The turning electric motor 21 can be constituted by, for example, a magnet-embedded IPM motor. Thereby, since a larger induced electromotive force can be generated, the electric power generated by the turning electric motor 21 at the time of regeneration can be increased.

  The charge / discharge control of the battery 19 is based on the state of charge of the battery 19, the operation state of the motor generator 12 (electric (assist) operation or power generation operation), and the operation state of the turning motor 21 (power running operation or regenerative operation). Performed by the controller 30.

  The resolver 22 is a sensor that detects the rotation position and rotation angle of the rotation shaft 21 </ b> A of the turning electric motor 21. The resolver 22 is mechanically connected to the turning electric motor 21 to detect a difference between the rotation position of the rotation shaft 21A before the rotation of the turning electric motor 21 and the rotation position after the left rotation or the right rotation. The rotation angle and the rotation direction of the rotation shaft 21A are detected. By detecting the rotation angle of the rotation shaft 21A of the turning electric motor 21, the rotation angle and the rotation direction of the turning mechanism 2 are derived.

  The mechanical brake 23 is a braking device that generates a mechanical braking force, and mechanically stops the rotating shaft 21 </ b> A of the turning electric motor 21. This mechanical brake 23 is switched between braking and release by an electromagnetic switch. This switching is performed by the controller 30.

  The turning speed reducer 24 is a speed reducer that reduces the rotational speed of the rotating shaft 21 </ b> A of the turning electric motor 21 and mechanically transmits it to the turning mechanism 2. Thereby, in the power running operation, the rotational force of the turning electric motor 21 can be increased and transmitted to the turning body as a larger rotational force. On the contrary, during the regenerative operation, the number of rotations generated in the revolving structure can be increased, and more rotational motion can be generated in the turning electric motor 21.

  The turning mechanism 2 can turn in a state where the mechanical brake 23 of the turning electric motor 21 is released, whereby the upper turning body 3 is turned leftward or rightward.

  The operating device 26 is an input device for an excavator driver to operate the turning electric motor 21, the lower traveling body 1, the boom 4, the arm 5, and the bucket 6, and includes levers 26A and 26B and a pedal 26C. The lever 26 </ b> A is a lever for operating the turning electric motor 21 and the arm 5, and is provided in the vicinity of the driver seat of the upper turning body 3. The lever 26B is a lever for operating the boom 4 and the bucket 6, and is provided in the vicinity of the driver's seat. The pedals 26C are a pair of pedals for operating the lower traveling body 1, and are provided under the feet of the driver's seat.

  The operating device 26 converts the hydraulic pressure (primary hydraulic pressure) supplied through the pilot line 25 into a hydraulic pressure (secondary hydraulic pressure) corresponding to the operation amount of the driver and outputs the converted hydraulic pressure. The secondary hydraulic pressure output from the operating device 26 is supplied to the control valve 17 through the hydraulic line 27 and detected by the pressure sensor 29.

  When each of the levers 26A and 26B and the pedal 26C is operated, the control valve 17 is driven through the hydraulic line 27, whereby the hydraulic pressure in the hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 is increased. Is controlled, the lower traveling body 1, the boom 4, the arm 5, and the bucket 6 are driven.

  One hydraulic line 27 is used for operating the hydraulic motors 1A and 1B (i.e., two in total), and two hydraulic lines 27 are used for operating the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 respectively (i.e., two). In reality, there are eight in total, but for convenience of explanation, they are collectively shown as one.

  In the pressure sensor 29 as the lever operation detection unit, a change in the hydraulic pressure in the hydraulic line 28 due to the operation of the lever 26 </ b> A is detected by the pressure sensor 29. The pressure sensor 29 outputs an electrical signal indicating the hydraulic pressure in the hydraulic line 28. This electrical signal is input to the controller 30. Thereby, the operation amount of the lever 26A can be accurately grasped. In the present embodiment, the pressure sensor is used as the lever operation detection unit. However, a sensor that reads the operation amount of the lever 26A with an electric signal may be used as it is.

  The controller 30 is a control device that performs drive control of the excavator, and includes an arithmetic processing device that includes a CPU (Central Processing Unit) and an internal memory.

  Next, the drive control of the hybrid construction machine according to the embodiment of the present invention will be described by taking the drive control of the excavator as an example.

  FIG. 3 is a diagram showing a model of the above-described excavator power system. In the model diagram of FIG. 3, the engine 50 corresponds to the engine 11 described above, and the assist motor 52 corresponds to the motor generator 12 having both functions of the motor and the generator. The hydraulic load 54 corresponds to a component driven by hydraulic pressure, and includes the above-described boom cylinder 7, arm cylinder 8, packet cylinder 9, and hydraulic motors 1A and 1B. However, when considered as a load for generating hydraulic pressure, the hydraulic load 54 corresponds to the main pump 14 as a hydraulic pump for generating hydraulic pressure. The electric load 56 corresponds to a component driven by electric power such as an electric motor or an electric actuator, and includes the turning electric motor 21 described above. The battery 58 is a capacitor and corresponds to the battery 19 described above. In this embodiment, a capacitor (electric double layer capacitor) is used as the battery 58.

  The hydraulic load 54 is supplied with hydraulic pressure generated by a hydraulic pump that generates hydraulic pressure (the main pump 14 described above). The engine 50 is driven by supplying power to the hydraulic pump. That is, the power generated by the engine 50 is converted into hydraulic pressure by the hydraulic pump and supplied to the hydraulic load 54.

  On the other hand, an assist motor 52 is also connected to the hydraulic pump, and power generated by the assist motor 52 can be supplied to the hydraulic pump for driving. That is, the electric power supplied to the assist motor 52 is converted into power by the assist motor 52, and the power is converted into hydraulic pressure by the hydraulic motor and supplied to the hydraulic load 54. At this time, the assist motor 52 operates as an electric motor.

  The electric load 56 is supplied with electric power from the battery 58 and driven. A case where the electric load 56 is driven is referred to as a power running operation. The electric load 56 can generate regenerative electric power, for example, like an electric motor / generator, and the generated regenerative electric power is supplied to the battery 58 and stored, or supplied to the assist motor 52 to assist the assist motor. It becomes the electric power which drives 52.

  The battery 58 is charged by the regenerative power from the electric load 56 as described above. Further, when the assist motor 52 receives power from the engine 50 and functions as a generator, the power generated by the assist motor 52 can be supplied to the battery 58 for charging. The electric power generated by the assist motor 52 can be directly supplied to the electric load 56 to drive the electric load 56.

  In the configuration as described above, it can be seen that the movement of electric power (power) has directionality when a portion related to electric power is viewed. If this directionality is taken as the output polarity, the polarity shown in FIG. 4 is obtained.

  Looking at the assist motor 52, when the engine 50 is assisted to generate hydraulic pressure and supply power to the hydraulic load 54, electric power is output as power. The output polarity of the assist motor 52 at this time is (+). On the other hand, when the assist motor 52 is driven by the driving force of the engine 50 to generate power, power is input to the assist motor 52. Accordingly, the output polarity of the assist motor 52 at this time is (−).

  As for the battery 58, when the electric load 56 or the assist motor 52 is driven by discharging, the output polarity is (+). On the other hand, regenerative power or power generated by the assist motor 52 may be supplied from the electric load 56 and charged. The output polarity of the battery 58 at this time is (-).

  Looking at the electrical load 56, if the output polarity when power is supplied and driven, that is, the power running operation is (+), the output polarity when regenerative power is generated is (−). It becomes.

  As described above, in the hybrid excavator, the output polarity is appropriately adjusted in consideration of the operation state of the assist motor 52 and the electric load 56 and the charging state of the battery 58, which are components related to electric power. It is necessary to determine the operating conditions. In particular, the distribution of the output to the hydraulic load 54 and the output to the electric load 56 can be controlled while adjusting the output polarity of the assist motor 52 so that the battery 58 is always properly charged. is important.

  Next, power distribution control performed in the above hybrid excavator will be described.

  FIG. 5 is a configuration diagram of a control system that performs power distribution control according to an embodiment of the present invention. The control system shown in FIG. 5 is a control system mounted on the hybrid excavator described above.

  The control system includes an engine 50, an assist motor 52, a hydraulic load 54 that is a hydraulic drive unit, an electric load 56 that is an electric drive unit, a battery 58 that is a capacitor, and a controller 30 that is a control unit that controls the operation and state of these. including.

  Engine speed information Ieng representing the engine speed is supplied from the engine 50 to the controller 30. From the hydraulic load 54, hydraulic system output information Ihyd that estimates the output state of the hydraulic pump is output and supplied to the controller 30. In addition, the electrical load 56 outputs electrical output information Ielc indicating an output state of an electrified actuator (for example, the turning electric motor 21) and the like, and is supplied to the controller 30. Further, from the battery 58, SOC information Ibts indicating the charging rate SOC at that time, and power storage input / output possible amount information Iioc obtained from the SOC and temperature are output and supplied to the controller 30. The controller 30 outputs the result calculated according to the algorithm described below based on the above information to the assist motor 52 as an assist command Casi.

  FIG. 6 is a functional block diagram of the controller 30. The storage input / output possible amount information Iioc and the electric system output information Ielc from the battery 58 are supplied to the first assist amount calculation unit 30a that performs electric load compensation. The first assist amount calculation unit 30a calculates a first assist request Rasi1 for requesting assistance by the assist motor 52 based on the storage input / output possible amount information Iioc and the electrical system output information Ielc, and sends it to the priority calculation unit 30d. Output.

  The engine speed information Ieng and the hydraulic system output information Ihyd from the engine 50 are supplied to the second assist amount calculation unit 30b that performs hydraulic assist. The second assist amount calculation unit 30b calculates a second assist request Rasi2 that requests assistance from the assist motor 52 based on the engine speed information Ieng and the hydraulic system output information Ihyd, and outputs the second assist request Rasi2 to the priority calculation unit 30d. .

  Further, the stored SOC information Ibts from the battery 58 is supplied to a third assist amount calculation unit 30c that performs storage amount control. The third assist amount calculation unit 30c calculates a third assist request Rasi3 for requesting assistance by the assist motor 52 based on the stored SOC information Ibts, and outputs the third assist request Rasi3 to the priority calculation unit 30d.

  The priority calculation unit 30d performs priority calculation on the input assist requests Rasi1 to Rasi3, and generates an assist command Casi based on the priorities of the first assist request Rasi1 to the third assist request Rasi3. This is output to the assist motor 52. Here, the priority calculation is performed by a pre-input determination index shown in FIGS. Which determination index is to be used is selected by the priority determination processing unit 30e, and the selected determination index is input to the priority calculation unit 30d as priority information Ipri.

  Here, the first to third assist amount calculation units 30a, 30b, and 30c will be described in more detail.

  When the output (or regeneration) of the electric load 56 cannot be covered by the battery 58, the first assist amount calculation unit 30a calculates a first assist request Rasi1 that requests the assist motor 52 to generate power (or power running). And output. This function is an electric load compensation function. FIG. 7 is a diagram illustrating a concept of a method of calculating the first assist request Rasi1 in the first assist amount calculation unit 30a.

  The amount of electric power (input / output amount) that can be charged and discharged differs depending on the state (temperature, degree of deterioration, etc.) and specifications of the battery 58 at that time. When the amount requested by the electric load 56 exceeds the range of the chargeable / dischargeable amount, a request command is issued to the assist motor 52 so as to cover the shortage by the power generation by the assist motor 52. This request command is the first assist request Rasi1.

  Here, it is assumed that the rotational speed of the engine 50 is controlled to be constant. In this case, the fuel consumption of the engine 50 depends on the rotational speed and torque of the engine 50. In addition, the supply of electric power to the electric load 56 is basically provided by the electric power from the battery 58, and the power that cannot be supplied is assisted by the power generation of the assist motor 52.

  In FIG. 7, white circles indicated by arrows indicating the electrical system output from the electrical load 56 indicate the amount of power to be supplied to the electrical load 56. Here, white circles representing the amount of power to be supplied to the electrical load 56 are plotted on a line indicating the chargeable / dischargeable amount of the battery 58. On this line, the chargeable amount and the dischargeable amount are indicated by hatched areas. The maximum value of the chargeable amount is determined by the maximum input value of the battery 58 at that time. On the other hand, the maximum value of the dischargeable amount is determined by the maximum output value of the battery 58 at that time.

  In the example shown in FIG. 7, the white circle indicated by the arrow indicating the electrical system output from the electrical load 56 exceeds the range of dischargeable amount. Therefore, in order to request that the assist motor 52 be driven as a generator to supply power by the amount exceeding this, that is, the value of the battery maximum output minus the value of the electric load system output, Assist request Rasi1 is output.

  When the value of the electric load system output from the electric load 56 is smaller than the value of the battery maximum output, it is not necessary to generate power with the assist motor 52, and the first assist request Rasi1 is not output.

  On the other hand, although not shown, when the electrical load 56 generates regenerative power, the electrical load system output is regenerative power and is used for charging the battery 58. In this case, the value of the electric load system output (regenerative power) and the value of the maximum input of the battery 58 are compared. When the value of the electrical load system output (regenerative power) exceeds the maximum input value of the battery 58, the difference is supplied to the assist motor 52 to drive the assist motor 52 as an electric motor. 1 assist request Rasi1 is output.

  As described above, the electric load compensation control is performed in the first assist amount calculation unit 30a, and the first assist request Rasi1 is output when necessary.

  The second assist amount calculation unit 30b determines whether or not the output to the hydraulic load 54 can be achieved by the power generated by the engine 50. If the engine 50 cannot provide the output, the assist motor 52 is driven as an electric motor to be electrically operated. A second assist request Rasi2 for requesting (assist) is calculated and output. This function is a hydraulic assist function. FIG. 8 is a diagram illustrating a concept of a method for calculating the second assist request Rasi2 in the second assist amount calculation unit 30b.

  First, the second assist amount calculation unit 30b calculates an output that can be covered by the engine 50 from the engine speed at that time. The engine output can be easily calculated by preparing a map based on engine characteristics in which, for example, data of an iso-fuel consumption diagram is set as a parameter in advance. Then, the second assist amount calculation unit 30b compares the calculated engine output value with the hydraulic system output value required by the hydraulic load 54. The value of the hydraulic system output required by the hydraulic load 54 can be calculated from, for example, the flow rate and pressure of hydraulic oil supplied to the hydraulic load 54.

  When the value of the hydraulic system output requested by the hydraulic load 54 exceeds the calculated engine output value, the assist motor 52 functions as an electric motor because it cannot answer the request of the hydraulic load 54 only by the engine output. Then, a request command is issued to supply power to the engine 50 side. This request command is the second assist request Rasi2.

  The third assist amount calculation unit 30c calculates a difference between the target SOC of the battery 58 and the current SOC, and calculates and outputs a third assist request Rasi3 in order to control the stored amount of the battery 58. This function is a storage amount control function. FIG. 9 is a diagram illustrating a concept of a method of calculating the third assist request Rasi3 in the third assist amount calculation unit 30c.

  It is preferable to maintain the SOC of the battery 58 at a desired value as much as possible. Therefore, the third assist amount calculation unit 30c calculates the difference between the target SOC and the current SOC, and drives the assist motor 52 based on the difference, or conversely, issues a request command for requesting power from the assist motor 52. Output. As shown in the graph of FIG. 9, when the current SOC is higher than the target SOC, in order to lower the SOC as indicated by arrow A, the assist motor 52 is required to be electrically operated (assisted) with the electric power from the battery 58. To do. On the other hand, when the current SOC is lower than the target SOC, in order to increase the SOC as indicated by arrow B, the assist motor 52 is requested to generate power so as to charge the battery 58. The above control can be achieved by performing PID control based on the difference between the target SOC and the current SOC.

  The priority calculation unit 30d calculates an assist command Casi that is a final command from the three assist requests Rasi1, Rasi2, and Rasi3 generated as described above. Hereinafter, a method for calculating the assist command Casi will be described.

  FIG. 10 is a table showing an algorithm used when generating the assist command Casi from the assist requests Rasi1, Rasi2, and Rasi3. In order to select the optimum assist request, it is first necessary to decide what is to be prioritized. In other words, it is necessary to decide whether to give priority to satisfying the electric load requirement, to give priority to satisfying the hydraulic load requirement, or to give priority to maintaining the SOC of the battery at a desired value. is there.

  In the example shown in FIG. 10, the value of the first assist request Rasi1 related to the electric load 56 is set to a, the value of the second assist request Rasi2 related to the hydraulic load 54 is set to b, and the third assist request related to the battery 58 is set. The value of Rasi3 is set to c. Satisfying the demand of the electrical load 56 is set as the highest priority with the priority 1, and then satisfying the demand of the hydraulic load 54 is set as the priority 2 with the next highest priority. The maintenance of 58 SOC is set as the priority 3, and the lowest priority is set.

  In the example shown in FIG. 10, assist requests a to c are arranged on the left side, upper side, and right side of the table, respectively, and the states are divided according to the possible values. And the optimal arithmetic expression is described in the column corresponding to each state. The embedding of the arithmetic expression in this table represents the priority.

  In the example shown in FIG. 10, the determination index is set as a → b → c in order from the highest priority as described above. When priority does not need to be considered, three assist requests a to c can be added, or a larger value can be selected by comparing the respective values. Here, the process of selecting the larger absolute value of the values to be compared is performed. In the present embodiment, the condition that the priority need not be considered is satisfied when the signs of the three assist requests a to c are the same (when all of the assist requests require “electric driving”). ) Only. In addition, when the codes of the three assist requests a to c are different, the code of the higher priority among them is adopted. That is, the algorithm is set such that the assist request a is added to the assist request a only when the assist request b or c has the same sign. Here, in this embodiment, since the hydraulic load 54 does not generate power, the assist request b related to the hydraulic load 54 does not take a negative value (b <0). Therefore, it is not necessary to calculate the assist command Casi for the column b in the table of FIG.

  For example, when a drive command for the turning electric motor 21 is issued by operating the lever 26, the controller 30 requests the controller 30 for power required for the power running operation of the turning electric motor 21, and generates an assist request Rasi1 in the electric load compensator 30a. To do. On the other hand, when a boom driving command is issued by operating the lever 26, the controller 30 requests an output required for driving the boom, and generates an assist request Rasi2 in the hydraulic assist unit 30b. Further, in the charged amount control unit 30c, an assist request Rasi3 is generated based on the stored SOC information in the battery 58 at that time. Here, since the assist request Rasi1 requests the assist motor to generate power by the power running operation of the turning electric motor 21, it is determined that a <0. Next, since the assist request Rasi2 to the assist motor requests assist by driving the boom, 0 <bt is determined. In this state, the request command is inconsistent between the power generation request to the assist motor by the turning electric motor 21 and the assist request to the assist motor by driving the boom.

  However, in the priority calculation unit 30d, the electric load assist request Rasi1 determined as the priority order 1, the hydraulic load assist request Rasi2 determined as the priority order 2, and the battery power generation request Rasi3 determined as the priority order 3 Therefore, even if the request commands from the driving units to the assist motor are inconsistent, it is possible to make a determination based on the priority order. Thereby, even if an assist request is issued from the boom, the power generation request from the turning electric motor 21 is given priority because the power generation request of the electric turning motor 21 is higher in the priority order.

  Then, from the battery storage state, it is determined that c <0 because the assist request Rasi3 to the assist motor requests power generation. The request from the battery storage state is inconsistent with the assistance request of the hydraulic assist having higher priority, but the power generation request of the electric load request is given priority, so the assist request Rasi3 from the battery storage state is reflected as it is. . As a result, a + c is determined based on the determination index, and an assist output command Casi is calculated based on the assist request Rasi1 and the assist request Rasi3.

  FIG. 11 is a diagram showing the flow of power relating to the assist motor 52 when the assist command Casi = a + c is set in FIG. The power generation amount of the assist motor 52 is determined by adding the assist request a from the electric load 56 and the assist request c from the battery 58. Based on the assist command Casi = a + c, the assist motor 52 is controlled so as to generate power by the amount of power based on the calculated value from a + c. Then, the electric power of the assist request a requested by the electric load 56 is supplied to the electric load 56, and the electric power of the assist request c requested by the battery 58 is supplied to the battery 58. The hydraulic load 54 requires an assist (that is, an electric driving (assist) operation of the assist motor 52), but since the highest priority is given to the request of the electric load 56 here, the assist request of the hydraulic load 54 is requested. b is not acceptable. Therefore, based on the determination of a + c based on the determination index, the controller 30 increases the engine torque of the engine that is rotating at a constant rotation so as to generate an electric energy corresponding to the assist output command Casi calculated from the assist request Rasi3. Let

  FIG. 12 is a diagram showing the flow of power related to the assist motor 52 when the assist command Casi = Max (a, b) is set in (ii) of FIG. The larger one of the assist request a from the electrical load 56 and the assist request b from the hydraulic load 54 is adopted to determine the engine assist power amount of the assist motor 52. Based on the assist command Casi = Max (a, b), the assist motor 52 is controlled to output the larger power of a and b. This is because, if the direction of the request is the same, if the larger request is satisfied, the other requests work simultaneously, and both requests can be satisfied at the same time. Then, the electric power of the assist request “a” that the electric load 56 desires to output is supplied to the assist motor 52, and the power of the assist request “b” required by the hydraulic load 54 is supplied from the assist motor 52 to the hydraulic load 54. The battery 58 is requesting power generation by the assist motor 52. However, since the highest priority is given to the request of the electric load 56 here, the assist request c of the battery 58 is not accepted.

  FIG. 13 is a diagram showing the flow of power related to the assist motor 52 when the assist command Casi = Max (a + c, b) is set in (iii) of FIG. The engine assist power amount of the assist motor 52 is determined by adopting the value calculated by adding the assist request a from the electric load 56 and the assist request c from the battery 58 and the assist request b from the hydraulic load 54 which is larger. It has been decided. Based on the assist command Casi = Max (a + c, b), the assist motor 52 is controlled to output the power of a + c or b. When the calculated value from a + c is larger than the value b, the power of the assist request a that the electric load 56 wants to output is supplied to the assist motor 52, and the power of the assist request c that the battery 58 wants to discharge is assisted from the battery 58. It is supplied to the motor 52. On the other hand, when the value of b is larger than the value calculated from a + c, the power of the assist request b requested by the hydraulic load 54 is supplied from the assist motor 52 to the hydraulic load 54.

  In the table shown in FIG. 10, the highest priority of the electric load request is set highest, the priority of the hydraulic assist (hydraulic load) request is set second highest, and the priority of the request by the storage amount control is set. It is the third. In this case, the request for the electric load is always accepted, and the electric load can be maintained as much as possible so as to be in the most appropriate operating state. For example, when a lift magnet is used as an electrical load, the power supply to the lift magnet can be given top priority to prevent the amount of power supplied to the lift magnet from being unexpectedly reduced. Drive control in consideration of safety can be performed. Further, in the case of a hybrid excavator, it is common to electrically drive a turning motor, and it is desired to preferentially drive turning. Therefore, in such a hybrid excavator, it is possible to satisfy the requirement of preferentially driving the turning by setting the highest priority of the electric load requirement.

  Further, by setting the priority of the request for the hydraulic load to the second, the output of the battery can be maximized without being influenced by the state of the battery. For this reason, the power supplied to the hydraulic load can be increased, and the hydraulic drive unit can be operated strongly. However, since there is a possibility that the storage rate of the battery may deteriorate, it is not preferable for continuous operation. In order to give priority to stable continuous operation, it is preferable to set the priority of the request by the storage amount control second and set the priority of the request of hydraulic assist (hydraulic load) third.

  In FIG. 14, in the algorithm shown in FIG. 10, the highest priority is set to satisfy the request of the hydraulic load 54 as the priority 1, and the second priority is set to satisfy the request for the storage amount control next. The priority is set to the highest and the priority is set to the lowest as the priority 3 to satisfy the request of the electric load 56.

  In the example shown in FIG. 14, as with the example shown in FIG. 10, assist requests a to c are arranged on the left side, upper side, and right side of the table, and the states are divided according to the possible values. And the optimal arithmetic expression is described in the column corresponding to each state. The embedding of the arithmetic expression in this table represents the priority. In the example shown in FIG. 14, the priority is set as b → c → a in order from the highest as described above.

  For example, in the table of FIG. 14, the sign of the assist request b is plus (0 <b), the sign of the assist request a is minus (0 <b), and the sign of the assist request c is also minus (c <0). In this case, the value of the assist command Casi is calculated as b as shown in (iv) of FIG. That is, since the signs of the three assist requests are not all the same (only b is positive and a and c are negative), the sign of the assist request b having the highest priority is adopted, and the sign of the assist request b (minus) Since there is no assist request having the same sign as), nothing is added to b, and the assist command Casi is set to b (Casi = b).

  FIG. 15 is a diagram showing the flow of power relating to the assist motor 52 when the assist command Casi = b is set in (iv) of FIG. The amount of power to be output from the assist motor 52 is determined only by the assist request b from the hydraulic load 54. Based on the assist command Casi = b, the assist motor 52 is controlled so as to output only the power amount b. The battery 58 requires power generation (that is, power generation operation of the assist motor 52). However, since the highest priority is given to the request of the hydraulic load 54 here, the assist request c of the battery 58 is not accepted. . The electric load 56 also requests power generation (that is, power generation operation of the assist motor 52), but since the highest priority is given to the request of the hydraulic load 54 here, the assist request a for the electric load 56 is a. Is not acceptable.

  FIG. 16 is a diagram showing the flow of power relating to the assist motor 52 when the assist command Casi = Max (a, b) is set in FIG. The larger one of the assist request a from the electric load 56 and the assist request b from the hydraulic load 54 is adopted to determine the engine assist power amount of the assist motor 52. Based on the assist command Casi = Max (a, b), the assist motor 52 is controlled so as to output the larger power of the assist request a from the electric load 56 and the assist request b from the hydraulic load 54. Then, the electric power of the assist request “a” that the electric load 56 desires to output is supplied to the assist motor 52, and the power of the assist request “b” required by the hydraulic load 54 is supplied from the assist motor 52 to the hydraulic load 54. The battery 58 requires power generation by the assist motor 52. However, since the highest priority is given to the request of the hydraulic load 54 here, the assist request c of the battery 58 is not accepted.

  FIG. 17 is a diagram showing the flow of power related to the assist motor 52 when the assist command Casi = Max (a + c, b) is set in (vi) of FIG. The calculated value obtained by adding the assist request “a” from the electric load 56 and the assist request “c” from the battery 58 and the value of the assist request “b” from the hydraulic load 54 which is larger are adopted, and the engine assist power amount of the assist motor 52 is increased. It has been decided. Based on the assist command Casi = Max (a + c, b), the assist motor 52 is controlled to output a calculated value from a + c or power of b. Then, the electric power of the assist request a that the electric load 56 wants to output is supplied to the assist motor 52, the power of the assist request b that the hydraulic load 54 requires is supplied from the assist motor 52 to the hydraulic load 54, and the assist request that the battery 58 wants to discharge. The electric power of c is supplied from the battery 58 to the assist motor 52. In this case, the assist request a for the electric load 56, the assist request b for the hydraulic load 54, and the assist request c for the battery 58 all have the same sign, and the assist motor 52 operates the same (power generation or electric (assist) operation). Therefore, all of the three assist requests a, b, and c are accepted.

  In the table shown in FIG. 14, the highest priority of the hydraulic load request is set to the highest, the priority of the request by the storage amount control is second, and the priority of the request of hydraulic assist (hydraulic load) is third. Yes. In this case, the request for the hydraulic load is always accepted, and the operation state that satisfies the request for the hydraulic load as much as possible can be maintained. For example, when there are many excavation works depending on the work content, the work of moving hydraulic drive units such as buckets, arms, and booms increases. In such a case, by setting the highest degree of demand for the hydraulic load to the highest level, it is possible to sufficiently supply the hydraulic pressure for performing the excavation work required by the operator. In addition, by setting the battery request priority to the second priority, the assist motor 52 can be electrically operated (assist) to supply power to the hydraulic load side, and the operation of the hydraulic drive unit is powerful. Can be given to a person.

  Although the case where the priority of the request based on the storage amount control (request of the battery 58) is set to the highest is not shown, for example, when working in an environment where the outside air temperature is high, the request of the battery 58 It is preferable to give the highest priority. Since the deterioration of the battery 58 is promoted when the outside air temperature is high, the deterioration of the battery 58 can be suppressed by maintaining the charging rate SOC as close to the target charging rate as possible.

  As described above, according to the present embodiment, for example, energy management can be performed in accordance with the characteristics of the device to be controlled, such as preferentially driving a motorized turning shaft. Further, in the parameter adjustment of the hybrid control, the adjustment in consideration of the operator's feeling can be realized by adjusting for each function or adjusting the priority.

It is a side view of a hybrid type shovel. It is a block diagram showing the structure of the drive system of the shovel shown in FIG. FIG. 2 is a diagram showing a model of a power system of the excavator shown in FIG. 1. It is a figure which shows the polarity which caught the directionality of the movement of electric power (power) as an output polarity. It is a block diagram of the control system which performs power distribution control by one Embodiment of this invention. It is a functional block diagram of the control part contained in the controller for performing control by one Embodiment of this invention. It is a figure which shows the concept of the method of calculating a 1st assistance request | requirement in a 1st assistance amount calculating part. It is a figure which shows the concept of the method of calculating a 2nd assistance request | requirement in a 2nd assistance amount calculating part. It is a figure which shows the concept of the method of calculating a 3rd assistance request | requirement in a 3rd assistance amount calculating part. It is a table | surface which shows the algorithm used when producing | generating an assist instruction | command from three assist requests | requirements. It is a figure which shows the flow of the motive power regarding the operation | movement of the assist motor performed by the assist command set in (i) of FIG. It is a figure which shows the flow of the motive power regarding operation | movement of the assist motor performed by the assist instruction | command set in (ii) of FIG. It is a figure which shows the flow of the power regarding the operation | movement of the assist motor performed by the assist instruction | command set in (iii) of FIG. It is a table | surface which shows an example of the algorithm used when producing | generating an assist instruction | command from three assist requests | requirements. It is a figure which shows the flow of the power regarding the operation | movement of the assist motor performed by the assist command set in (iv) of FIG. It is a figure which shows the flow of the motive power regarding operation | movement of the assist motor performed by the assist command set in (v) of FIG. It is a figure which shows the flow of the motive power regarding operation | movement of the assist motor performed by the assist instruction | command set in (vi) of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Traveling mechanism 2 Turning mechanism 3 Upper turning body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Motor generator 13 Reducer 14 Main pump 15 Pilot pump 16 High pressure Hydraulic line 17 Control valve 18 Inverter 19 Battery 20 Inverter 21 Electric motor for turning 23 Mechanical brake 24 Turning speed reducer 25 Pilot line 26 Operating device 26A, 26B Lever 26C Pedal 27 Hydraulic line 28 Hydraulic line 29 Pressure sensor 30 Controller 31 Speed command converter 32 Drive control device 40 Turning drive control device 50 Engine 52 Assist motor 54 Hydraulic load 56 Electric load 58 Battery

Claims (6)

A hydraulic generator that converts the output of the engine into hydraulic pressure and supplies it to a hydraulic drive unit; a motor generator that is connected to the engine and functions as both a motor and a generator;
A capacitor that supplies electric power to the motor generator to function as an electric motor;
An electric drive unit that is driven by electric power from the electric storage device and the motor generator, and generates regenerative electric power to supply to at least one of the electric storage device and the motor generator;
A hybrid construction machine having a controller for controlling the operation of the motor generator,
The control unit calculates a second assist power request amount required by the hydraulic drive unit, calculates a first assist power request amount required by the electric load, and maintains a charge rate of the battery. And calculating a priority order of the first, second, and third assist power request amounts, and determining an output value of the motor generator based on the determination result. Hybrid construction machine. The hybrid construction machine according to claim 1,
The hybrid construction machine, wherein the control unit calculates the second assist power requirement amount based on an operating state of the engine and a load of the hydraulic drive unit. The hybrid construction machine according to claim 1,
The hybrid construction machine, wherein the control unit calculates the first assist power request amount based on an amount of electric power that can be input to and output from the capacitor and a load of the electric drive unit. The hybrid construction machine according to claim 1,
The hybrid construction machine, wherein the control unit calculates the first assist power request amount based on a usage range of the battery and a load of the electric drive unit. A hybrid construction machine according to claim 4,
Wherein, when the load of the electric drive unit is in the range of use of the capacitor, the hybrid construction machine, which comprises setting the first assist power demand from the capacitor to zero. The hybrid construction machine according to claim 1,
The hybrid construction machine, wherein the control unit calculates the third assist power request amount based on a difference between a target charging rate and a current charging rate.

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