JP5355260B2 - Hybrid work machine and method for calculating efficiency factor thereof - Google Patents

Description

  The present invention relates to a hybrid work machine including an assist motor that assists an engine or converts engine power into electric power, and a method for calculating an efficiency coefficient thereof.

  In recent years, power generation machines such as construction work machines have been required to have performance such as fuel saving, low pollution, and low noise in consideration of the global environment. In order to satisfy these demands, work machines such as hydraulic excavators that use an electric motor instead of a hydraulic pump or as an auxiliary to an engine such as an internal combustion engine have appeared. In a work machine incorporating an electric motor, surplus kinetic energy generated from the electric motor is converted into electric energy and stored in a capacitor or the like.

  A power supply source required for a mechanical load such as a hydraulic motor is efficiently distributed to an engine serving as a power source and a capacitor serving as a power source.

JP 2008-49761 A

  Power loss occurs during conversion from power to power and from power to power. In order to efficiently distribute the desired power to the power source and the power source, it is desired to accurately calculate the efficiency at the time of conversion from power to power and from power to power.

According to one aspect of the invention,
An engine that generates torque by burning fuel,
An assist motor capable of selectively performing power generation operation and assist operation;
A torque transmission machine for mutually transmitting and receiving torque of the engine and torque of the assist motor;
A power storage circuit that is charged by the power generated by the assist motor and supplies the assist motor by discharging the stored power; and
A first external load that is a mechanical load of the engine;
A second external load which is a mechanical load;
A regenerative motor that applies braking force to the second external load by regenerating power from the second external load;
A control device,
The torque transmission mechanism transmits torque generated by the engine and torque generated by the assist motor to the first external load,
Regenerative power generated by the regenerative motor is supplied to the power storage circuit,
The control device causes the assist motor to perform an assist operation, and measures the charge / discharge power of the power storage circuit, the drive current of the assist motor, and the rotation speed when the assist motor is in an assist operation.
Based on the measured charge / discharge power, the drive current, and the rotational speed, a hybrid type that calculates a first efficiency coefficient indicating a relationship between the transmission / reception power, the drive current, and the rotational speed of the assist motor during the assist operation. A work machine is provided.

According to another aspect of the invention,
An engine that generates torque by burning fuel,
An assist motor capable of selectively performing power generation operation and assist operation;
A torque transmission machine for mutually transmitting and receiving torque of the engine and torque of the assist motor;
A power storage circuit that is charged by the power generated by the assist motor and discharges the stored power to supply power to the assist motor ;
A first external load that is a mechanical load of the engine;
A second external load which is a mechanical load;
Have a <br/> regenerative motor that gives a braking force to an external load of the second by regenerative power from said second external load,
The torque transmission mechanism transmits torque generated by the engine and torque generated by the assist motor to the first external load,
In hybrid working machine regenerative power generated by the regenerative motor Ru is supplied to the storage circuit,
A step of assisting the assist motor, and measuring the charge / discharge power of the power storage circuit, the drive current of the assist motor, and the rotation speed when the assist motor is being assisted.
Calculating a first efficiency coefficient indicating a relationship between the transmission / reception power of the assist motor, the rotation speed, and the drive current during the assist operation based on the measured charge / discharge power, the drive current, and the rotation speed; A method for calculating the efficiency coefficient of a hybrid work machine having the above is provided.

  The efficiency coefficient can be calculated by the above procedure. By using the calculated efficiency coefficient, it is possible to efficiently distribute power and electric power.

It is a side view of the hybrid type working machine by an Example. It is a block diagram of the hybrid type working machine by an Example. It is the equivalent circuit schematic of the electrical storage circuit of the hybrid type working machine by an Example. It is a block diagram for demonstrating the flow of motive power and electric power. It is a functional block diagram of a control device. It is a graph which shows the relationship between an electrical load output command value and an electrical load output request value. It is a graph which shows the relationship between a hydraulic load output command value and a hydraulic load output request value. (8A) and (8B) are graphs showing the relationship between the storage circuit output command value and the storage circuit output target value. It is a flowchart which shows the calculation method of the efficiency coefficient by an Example. (10A) and (10B) are flowcharts of steps SA1 and SA3 in FIG. 9, respectively. It is a flowchart which shows the other calculation method of the efficiency coefficient by an Example.

  FIG. 1 shows a side view of a hybrid work machine according to an embodiment. An upper swing body 3 is mounted on the lower traveling body (base body) 1 via a swing mechanism 2. The turning mechanism 2 includes an electric motor (motor), and turns the upper turning body 3 clockwise or counterclockwise. A boom 4 is attached to the upper swing body 3. The boom 4 swings up and down with respect to the upper swing body 3 by a hydraulically driven boom cylinder 7. An arm 5 is attached to the tip of the boom 4. The arm 5 swings in the front-rear direction with respect to the boom 4 by an arm cylinder 8 that is hydraulically driven. A bucket 6 is attached to the tip of the arm 5. The bucket 6 swings up and down with respect to the arm 5 by a hydraulically driven bucket cylinder 9. The upper swing body 3 further includes a cabin 10 that accommodates a driver.

  FIG. 2 shows a block diagram of the hybrid work machine. In FIG. 2, the mechanical power system is represented by a double line, the high-pressure hydraulic line is represented by a thick solid line, the electric system is represented by a thin solid line, and the pilot line is represented by a broken line.

  The drive shaft of the engine 11 is connected to one rotating shaft of the torque transmitter 13. The engine 11 is an engine that generates a driving force by burning fuel, for example, an internal combustion engine such as a diesel engine. The engine 11 is always driven during operation of the work machine.

  A drive shaft of the assist motor 12 is connected to another rotating shaft of the torque transmitter 13. The assist motor 12 can perform both driving operations of assist (power running) operation and power generation (regeneration) operation. As the assist motor 12, for example, an internal magnet embedded (IPM) motor in which a magnet is embedded in the rotor is used.

  The drive shaft of the main pump 14 is connected to another rotating shaft of the torque transmitter 13. The main pump 14 becomes an external load of the engine 11.

  When the load applied to the engine 11 is large, the assist motor 12 performs an assist operation, and the power generated by the assist motor 12 is transmitted to the main pump 14 via the torque transmitter 13. Thereby, the load applied to the engine 11 is reduced. On the other hand, when the load applied to the engine 11 is small, the power generated by the engine 11 is transmitted to the assist motor 12 via the torque transmitter 13, whereby the assist motor 12 is operated for power generation. Switching between the assist operation and the power generation operation of the assist motor 12 is performed by an inverter 18 connected to the assist motor 12. The inverter 18 is controlled by the control device 30.

  The control device 30 alerts the driver by displaying the deterioration state of various devices on the display device 35.

  The main pump 14 supplies hydraulic pressure to the control valve 17 via the high pressure hydraulic line 16. The control valve 17 distributes hydraulic pressure to the hydraulic motors 1 </ b> A and 1 </ b> B, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9 according to a command from the driver. The hydraulic motors 1A and 1B drive the two left and right crawlers provided in the lower traveling body 1 shown in FIG.

  An input / output terminal of the electric system of the assist motor 12 is connected to the power storage circuit 90 via the inverter 18. Further, a regenerative motor for turning 21 is connected to the storage circuit 90 via another inverter 20. Power storage circuit 90 includes a capacitor and a converter that controls charging and discharging of the capacitor. For example, an electric double layer capacitor is used as the capacitor. The detailed configuration of the storage circuit 90 will be described later with reference to FIG. The storage circuit 90 and the inverter 20 are controlled by the control device 30.

  During a period in which the assist motor 12 is being assisted, necessary power is supplied from the power storage circuit 90 to the assist motor 12, and the assist motor 12 outputs mechanical power (power). During the period in which the assist motor 12 is in the power generation operation, necessary power is supplied from the engine 11 and electric power (electric power) is output. The electric power generated by the assist motor 12 is supplied to the power storage circuit 90. The inverter 18 receives a command from the control device 30 and controls the operation of the assist motor 12 so as to output the commanded power or electric power.

  The regenerative motor for turning 21 is AC-driven by a pulse width modulation (PWM) control signal from the inverter 20, and a power running operation for generating power and a regenerative operation for generating electric power are selectively performed. The inverter 20 receives a command from the control device 30 and controls the operation of the regenerative motor 21 for turning so that the commanded power is generated or the commanded regenerative power is generated. For example, an IPM motor is used as the regenerative motor 21 for turning. An IPM motor generates a large induced electromotive force during regeneration.

  During the power running operation of the regenerative motor 21 for turning, electric power is supplied from the power storage circuit 90 to the regenerative motor 21 for turning. The power of the regenerative motor for turning 21 is transmitted to the turning mechanism 2 shown in FIG. At this time, the speed reducer 24 decreases the rotation speed. As a result, the torque generated by the regenerative motor for turning 21 is increased and transmitted to the turning mechanism 2. Further, during the regenerative operation, the rotational motion of the upper swing body 3 is transmitted to the regenerative motor 21 for rotation via the speed reducer 24, so that the regenerative motor 21 for revolving generates regenerative power. This regenerative electric power gives a braking force to the turning mechanism 2. At this time, the speed reducer 24 increases the rotation speed, contrary to the power running operation. Thereby, the rotation speed of the regenerative motor 21 for rotation can be raised. The regenerative power is supplied to the power storage circuit 90.

  The resolver 22 detects the position in the rotation direction of the rotation shaft of the regenerative motor 21 for turning. The detection result is input to the control device 30. By detecting the position of the rotating shaft in the rotational direction before and after operation of the regenerative motor 21 for turning, the turning angle and the turning direction are derived.

  A mechanical brake 23 is connected to the rotating shaft of the regenerative motor 21 for turning, and generates a mechanical braking force. The braking state and the released state of the mechanical brake 23 are controlled by the control device 30 and switched by an electromagnetic switch.

  The pilot pump 15 generates a pilot pressure necessary for the hydraulic operation system. The generated pilot pressure is supplied to the operating device 26 via the pilot line 25. The operating device 26 includes a lever and a pedal and is operated by a driver. The operating device 26 converts the primary side hydraulic pressure supplied from the pilot line 25 into a secondary side hydraulic pressure in accordance with the operation of the driver. The secondary side hydraulic pressure is transmitted to the control valve 17 via the hydraulic line 27 and to the pressure sensor 29 via the other hydraulic line 28.

  The detection result of the pressure detected by the pressure sensor 29 is input to the control device 30. Thereby, the control apparatus 30 can detect the operation state of the lower traveling body 1, the turning mechanism 2, the boom 4, the arm 5, and the bucket 6. The control device 30 can detect the operation amount of the lever with high accuracy via the pressure sensor 29.

  When the boom 4 is lowered, the pressure oil flowing through the hydraulic path of the boom cylinder 7 drives the boom regenerative hydraulic motor 42. The boom hydraulic motor 42 converts the flow of pressure oil into rotational force and supplies power to the boom regenerative motor 41. The boom regenerative motor 41 converts the power supplied from the boom regenerative hydraulic motor 42 into electric power. The electric power regenerated by the boom regenerative motor 41 is supplied to the power storage circuit 90 via the inverter 40.

  FIG. 3 shows an equivalent circuit diagram of the power storage circuit 90. The storage circuit 90 includes a capacitor 19, a converter 100, and a DC bus line 110. A capacitor 19 is connected to a pair of power supply connection terminals 103A and 103B of the converter 100, and a DC bus line 110 is connected to a pair of output terminals 104A and 104B. One power connection terminal 103B and one output terminal 104B are grounded.

  The DC bus line 110 is connected to the assist motor 12, the turning regenerative motor 21, and the boom regenerative motor 41 via inverters 18, 20, and 40. The voltage generated on the DC bus line 110 is measured by the voltmeter 111, and the measurement result is input to the control device 30.

  A series circuit in which the collector of the step-up insulated gate bipolar transistor (IGBT) 102A and the emitter of the step-down IGBT 102B are connected to each other is connected between the output terminals 104A and 104B. The emitter of the step-up IGBT 102A is grounded, and the collector of the step-down IGBT 102B is connected to the output terminal 104A on the high voltage side. An interconnection point between the step-up IGBT 102A and the step-down IGBT 102B is connected to the high-voltage side power supply connection terminal 103A via the reactor 101.

  Diodes 102a and 102b are connected in parallel to the step-up IGBT 102A and the step-down IGBT 102B, respectively, such that the direction from the emitter to the collector is the forward direction. A smoothing capacitor 105 is inserted between the output terminals 104A and 104B.

  A capacitor voltmeter 106 connected between the power supply connection terminals 103 </ b> A and 103 </ b> B measures a voltage between terminals of the capacitor 19. A capacitor ammeter 107 inserted in series with the reactor 101 measures the charge / discharge current of the capacitor 19. The measurement results of voltage and current are input to the control device 30.

  The control device 30 applies a pulse width modulation (PWM) voltage for control to the gate electrodes of the step-up IGBT 102A and the step-down IGBT 102B.

  Hereinafter, the boosting operation (discharging operation) will be described. A PWM voltage is applied to the gate electrode of the boosting IGBT 102A. When the boosting IGBT 102A is turned off, an induced electromotive force is generated in the reactor 101 in a direction in which a current flows from the high-voltage power supply connection terminal 103A toward the collector of the boosting IGBT 102A. This electromotive force is applied to the DC bus line 110 via the diode 102b. Thereby, the DC bus line 110 is boosted.

  Next, the step-down operation (charging operation) will be described. A PWM voltage is applied to the gate electrode of the step-down IGBT 102B. When the step-down IGBT 102B is turned off, an induced electromotive force is generated in the reactor 101 in a direction in which a current flows from the emitter of the step-down IGBT 102B toward the high-voltage side power supply connection terminal 103A. The capacitor 19 is charged by this induced electromotive force. Note that the current in the direction of discharging the capacitor 19 is positive, and the current in the direction of charging is negative.

  FIG. 4 shows the flow of power and electric power in the hybrid work machine according to the embodiment. The output power of the engine 11 is Pg, the output power of the assist motor 12 is PMa, and the power input to the main pump 14 is Ph. When the assist motor 12 is being assisted, the power Pg generated by the engine 11 and the power PMa generated by the assist motor 12 are supplied to the main pump 14. When the assist motor 12 is in a power generation operation, a part of the power Pg of the engine 11 is supplied to the assist motor 12. The power PMa generated by the assist motor 12 is positive, and the power PMa supplied to the assist motor 12 is negative.

  The charge / discharge power of the capacitor 19 of the storage circuit 90 is Ps. The discharge power Ps is positive and the charge power Ps is negative. The electric power transmitted / received between the storage circuit 90 and the inverters 18, 20, and 40 is assumed to be Psa, Psc, and Psb, respectively. The powers Psa, Psc, Psb supplied from the storage circuit 90 to the inverters 18, 20, 40 are positive, and the powers Psa, Psc, Psb supplied from the inverters 18, 20, 40 to the storage circuit 90 are negative.

  The power transmitted / received between the inverter 18 and the assist motor 12 is referred to as PCa (hereinafter referred to as “control output PCa”). The control output PCa is calculated by obtaining the torque by multiplying the drive current Ia flowing through the assist motor 12 by a torque constant, and further multiplying by the rotation speed Na of the assist motor 12. The rotation speed Na of the assist motor 12 is measured by the speed sensor 37, and the measurement result is input to the control device 30. The drive current Ia of the assist motor 12 is measured by the inverter 18, and the measurement result is input to the control device 30. A driving current (generated current) Ia and a control output PCa when the assist motor 12 is in a power generation operation are defined as negative.

The efficiency coefficient ηa ₁ when the assist motor 12 is in the assist operation and the efficiency coefficient ηa ₂ when the power generation operation is performed are defined as follows.

  The power transmitted and received between the inverter 20 and the regenerative motor 21 for rotation is PCc (hereinafter referred to as “control output PCc”). The control output PCc is calculated by obtaining the torque by multiplying the driving current Ic flowing through the regenerative motor 21 for rotation by a torque constant, and further multiplying the rotation speed Nc of the regenerative motor 21 for rotation. The rotation speed Nc of the regenerative motor 21 for rotation is measured by the speed sensor 38, and the measurement result is input to the control device 30. The drive current Ic of the regenerative motor for rotation 21 is measured by the inverter 20, and the measurement result is input to the control device 30. The drive current (current generated) Ic and the control output PCc when the regenerative motor 21 for revolving is in a regenerative operation are defined as negative.

The efficiency coefficient ηc ₁ when the turning regenerative motor 21 is in a power running operation and the efficiency coefficient ηc ₂ when the regenerative operation is in operation are defined as follows.

  The power transmitted and received between the inverter 40 and the boom regenerative motor 41 is referred to as PCb (hereinafter referred to as “control output PCb”). The control output PCb is calculated by obtaining a torque by multiplying the driving current Ib flowing through the boom regenerative motor 41 by a torque constant, and further multiplying the rotation number Nb of the boom regenerative motor 41. The rotation speed Nb of the boom regenerative motor 41 is measured by the speed sensor 39, and the measurement result is input to the control device 30. The boom regenerative motor 41 performs only the regenerative operation. The drive current (current generated) Ib and the control output PCb at this time are defined as negative.

The efficiency coefficient ηb ₂ when the boom regenerative motor 41 is in a regenerative operation is defined as follows.

  A method for obtaining these efficiency coefficients will be described later. The relationship between the machine output PMa defined by the product of the torque Ta generated on the rotation shaft of the assist motor 12 and the rotation speed Na and the control output PCa is determined in advance. Similarly, the relationship between the control output PCc of the turning regenerative motor 21 and the mechanical output PMc and the relationship between the control output PCb of the boom regenerative motor 41 and the mechanical output PMb are calculated in advance.

  By applying the efficiency coefficients shown in Equations 1 to 3, the machine outputs PMa, PMb, and PMc are converted into transmission / reception powers Psa, Psb, and Psc via the control outputs PCa, PCb, and PCc, respectively, and transmitted and received in reverse. The electric powers Psa, Psb, and Psc can be converted into mechanical outputs PMa, PMb, and PMc, respectively.

  Since the charging / discharging power Ps of the storage circuit 90 is the sum of transmission / reception power among the assist motor 12, the regenerative motor 21 for turning, and the regenerative motor 41 for boom, the following equation is established.

  FIG. 5 shows a block diagram of functions of the control device 30. Hydraulic load output request value Phr, boom load output request value PCbr, turning load output request value PCcr, engine speed Nact, and capacitor voltage Vm of power storage circuit 90 are input to control device 30.

  The hydraulic load output request value Phr is the total power required for the hydraulic mechanism driven by the hydraulic pressure such as the hydraulic motors 1A and 1B, the boom cylinder 7, the arm cylinder 8 and the bucket cylinder 9 shown in FIG. . For example, the hydraulic load output request value Phr is calculated from the operation amount of the operation lever operated by the operator.

  The boom load output request value PCbr is a request value for power transmitted and received between the inverter 40 and the boom regenerative motor 41 shown in FIG. Since the boom regenerative motor 41 does not perform the power running operation, the boom load output request value PCbr takes 0 or a negative value. The boom load output request value PCbr is calculated from the operation amount of the operation lever operated by the operator.

  The turning load output request value PCcr is a request value of power transmitted and received between the inverter 20 and the turning regenerative motor shown in FIG. The turning load output request value PCcr becomes positive when the regenerative motor 21 for turning is powered, and becomes negative when the regenerative operation is performed. For example, the turning load output request value PCcr is calculated from the operation amount of the operation lever operated by the operator.

  The engine speed Nact corresponds to the actual speed of the engine 11 shown in FIG. The engine 11 is always driven during operation of the work machine, and its rotation speed Nact is detected. The capacitor voltage Vm corresponds to the voltage between the terminals of the capacitor 19 shown in FIG.

  The engine speed Nact is input to the engine output range determination block 32. The engine output range determination block 32 stores a map or conversion table for obtaining the engine output upper limit value Pgomax and the engine output lower limit value Pgomin from the engine speed Nact. The engine output range determination block 32 calculates an engine output upper limit value Pgomax and an engine output lower limit value Pgomin from the input engine speed Nact, and gives them to the power distribution block 35.

  The capacitor voltage Vm is input to the SOC calculation block 33A. The SOC calculation block 33A calculates a charging rate (SOC) of the capacitor from the inputted capacitor voltage Vm. The calculated charging rate is given to the storage circuit output range determination block 33B and the storage circuit output target value determination block 33C.

  The storage circuit output range determination block 33B stores a map or conversion table for calculating the storage circuit output upper limit value Psomax and the storage circuit output lower limit value Psomin from the charging rate. The storage circuit output range determination block 33B determines a storage circuit output upper limit value Psomax and a storage circuit output lower limit value Psomin based on the charging rate. The storage circuit output upper limit value Psomax corresponds to the upper limit value of the power output from the storage circuit 90. The storage circuit output lower limit value Psomin is negative, and the absolute value thereof corresponds to the upper limit value of the power supplied to the storage circuit 90. An appropriate range of the input / output power of the storage circuit 90 is defined by the storage circuit output upper limit value Psomax and the storage circuit output lower limit value Psomin. The determined storage circuit output upper limit value Psomax and storage circuit output lower limit value Psomin are input to the power distribution block 35.

  Hereinafter, an example of a method for calculating the storage circuit output upper limit value Psomax and the storage circuit output lower limit value Psomin will be described. An appropriate range of charge / discharge current and an appropriate range of charge rate are determined for the capacitor 19 of the storage circuit 90. The storage circuit output upper limit value Psomax is set so that the discharge current of the capacitor does not exceed the upper limit value of the appropriate range, and the charging rate of the capacitor does not fall below the lower limit value of the appropriate range. The storage circuit output lower limit value Psomin is set so that the charging current of the capacitor does not exceed the upper limit value of the appropriate range, and the charging rate of the capacitor does not exceed the upper limit value of the appropriate range.

  The storage circuit output target value determination block 33C stores a map or conversion table for calculating the storage circuit output target value Psot from the charging rate. The storage circuit output target value determination block 33C determines a storage circuit output target value Psot based on the charging rate. The determined storage circuit output target value Psot is input to the power distribution block 35.

  Hereinafter, an example of a method for calculating the storage circuit output target value Psot will be described. A target value of the charging rate is determined for the capacitor 19 of the storage circuit 90. The storage circuit output target value Psot is determined so that the actual charging rate approaches the target value of the charging rate. For example, when the actual charging rate is higher than the target value of the charging rate, it is preferable to discharge the capacitor, and thus the storage circuit output target value Psot becomes positive. On the other hand, when the actual charging rate is lower than the target value of the charging rate, it is preferable to charge the capacitor, and thus the storage circuit output target value Psot becomes negative. The absolute value of the storage circuit output target value Psot is proportional to the deviation of the actual charging rate when the charging rate target value is used as a reference.

  The power distribution block 35 determines a hydraulic load output command value Pho, an assist motor power command value Psao, a regenerative motor power command value Psco for turning, a regenerative motor power command value for boom Psbo, and a storage circuit output command value Pso. A method for determining these command values will be described with reference to FIGS.

With reference to FIG. 6, a method of calculating the control output command value PCco of the regenerative motor 21 for turning and the control output command value PCbo of the regenerative motor 41 for boom will be described. First, the turning load output request value PCcr is converted into a turning load power request value Pscr. Specifically, the conversion is performed by the method described with reference to FIG. At this time, when the turning load output request value PCcr is positive, that is, when accelerating the turning, the efficiency coefficient ηc ₁ during the power running operation is applied. When the turning load output request value PCcr is negative, that is, when the turning is decelerated, the efficiency coefficient ηc ₂ during the regenerative operation is applied.

  Next, the boom load output request value PCbr is converted into a boom load power request value Psbr. The sum of the turning load power request value Pscr and the boom load power request value Psbr is defined as the electric load power request value Pser.

  The horizontal axis of FIG. 6 represents the power demand value Pser of the electric load. The vertical axis represents the power command value Pseo for the electrical load. The output power of the engine 11 as a power source and the output power of the power storage circuit 90 as a power source are distributed to the power command value Pseo of the electric load. When calculating the distribution method, the engine output upper limit value Pgomax, the engine output lower limit value Pgomin, and the hydraulic load output request value Phr are each converted into electric power. This conversion can be performed by the same method as the method of converting the machine output PMa shown in FIG. 4 into the electric power Psa.

When the engine output upper limit value Pgomax is converted into electric power, the conversion coefficient ηa ₂ during power generation is applied. When converting the engine output lower limit value Pgomin and the hydraulic load output request value Phr into electric power, the conversion factor to be applied differs depending on the magnitude relationship between the hydraulic load output request value Phr and the engine output lower limit value Pgomin. When Phr> Pgomin, applying a conversion factor .eta.a ₁ during assist operation, when the Phr <Pgomin, applying a conversion factor .eta.a ₂ at the time of power generation.

When the electric load power requirement value Pser is larger than the total value Pmax ₁ of the power conversion value of the engine output upper limit value Pgomax and the storage circuit output upper limit value Psomax, the electric load power command value Pseo is set to the total value Pmax _1. Equal to That is,
Pseo = (power conversion value of Pgomax) + Psomax
And This means that the power command value Pseo of the electric load does not exceed the maximum power that can be extracted from the engine 11 and the power storage circuit 90.

When the power demand value Pser of the electric load is smaller than a value Pmin _{1 obtained} by subtracting the power conversion value of the hydraulic load output request value Phr and the absolute value of the storage circuit output lower limit value Psomin from the power conversion value of the engine output lower limit value Pgomin. Makes the electric power command value Pseo of the electric load equal to this value Pmin ₁ . That is,
Pseo = (Electric power conversion value of Pgomin) − (Electric power conversion value of Phr) + Psomin
And Since Psomin is a negative value, in the above formula, the operator added to Psomin is “+” (plus).

  This equation is applied, for example, when only a part of the regenerated power can be used as the charging power for the storage circuit 90. The engine 11 is operated so that the power extracted from the engine 11 is minimized, and the assist motor 12 is assisted by using excessive regenerative power. By supplying power for assist operation from the power storage circuit 90 to the assist motor 12, the total power supplied to the power storage circuit 90 is controlled so as not to exceed the allowable upper limit value of the charging power.

When the electric load power requirement value Pser is between Pmax ₁ and Pmin ₁ , the electric load electric power command value Pseo is made equal to the electric load electric power requirement value Pser. That is,
Pseo = Pser
And This equation means that the required output is secured for the electrical load. At this time, the required output is ensured for both the turning power command value Psao and the boom power command value Psbo.

When the power request value Pser exceeds Pmax ₁ or is lower than Pmin ₁ , as an example, the ratio between the power command value Psco for turning and the power command value Psbo for boom is the power request value Pscr and Psbr. The power command value Pseo is distributed to both so as to be equal to the ratio. In particular,
Psco = (Pscr / Pser) Pseo
Psbo = (Psbr / Pser) Pseo
And

A method for determining the hydraulic load output command value Pho will be described with reference to FIG. The horizontal axis represents the hydraulic load output request value Phr, and the vertical axis represents the hydraulic load output command value Pho. The hydraulic load output request value Phr exceeds a value Pmax ₂ obtained by subtracting the power conversion value of the electric load power command value Pseo from the total value of the engine output upper limit value Pgomax and the power conversion value of the storage circuit output upper limit value Pbomax. If the hydraulic load output command value Pho, equal to the value Pmax _2. That is,
Pho = Pgomax + (Psomax power conversion value) − (Pseo power conversion value)
And This means that the hydraulic load output command value Pho does not exceed the remaining power obtained by extracting the power corresponding to the power command value Pseo of the electric load that has already been determined from the maximum power that can be extracted from the engine 11 and the power storage circuit 90. To do.

When the hydraulic load output request value Phr is equal to or less than Pmax ₂ , the hydraulic load output command value Pho is made equal to the hydraulic load output request value Phr. That is,
Pho = Phr
And This means that the required output is secured for the hydraulic load.

When converting the storage circuit output upper limit value Psomax and the electric load power command value Pseo into power, when Psomax> Pseo, the efficiency factor ηa ₁ during assist operation of the assist motor is applied, and when Psomax <Pseo, power generation The hourly efficiency factor ηa ₂ is applied.

8A and 8B show the relationship between the storage circuit output target value Psot and the storage circuit output command value Pso. From the total value of the power command value Pseo of the electrical load determined based on the graph shown in FIG. 6 and the power conversion value of the hydraulic load output command value Pho determined based on the graph shown in FIG. the value obtained by subtracting the power conversion value of the output lower limit value Pgomin and Pmax _3. When converting the hydraulic load output command value Pho and the engine output lower limit value Pgomin into electric power, the efficiency coefficient ηa ₁ during assist operation is applied when Pho> Pgomin, and the efficiency coefficient ηa ₂ during power generation is calculated when Pho <Pgomin. Apply.

From the total value of the power command value Pseo and the hydraulic load output command value power conversion value Pho electrical load, a value obtained by subtracting the power conversion value of the engine output upper limit value Pgomax and Pmin _3. When converting the hydraulic load output command value Pho and the engine output upper limit value Pgomax into electric power, the efficiency coefficient ηa ₁ during assist operation is applied when Pho> Pgomax, and the efficiency coefficient ηa ₂ during power generation is applied when Pho <Pgomax. Apply.

FIG. 8A shows a case where Pmax ₃ is smaller than the storage circuit output upper limit value Psomax determined by the storage circuit output range determination block 33B of FIG. 5 and Pmin ₃ is larger than the storage circuit output lower limit value Psomin. When the storage circuit output target value Psot exceeds Pmax ₃ , the storage circuit output command value Pso is made equal to Pmax ₃ . This means that since the electric power that can be taken out from the storage circuit 90 is sufficiently large, the engine 11 is operated at the output lower limit value Pgomin and excessive electric power more than necessary is not taken out from the storage circuit 90. When the storage circuit output target value Psot falls below Pmin ₃ , the storage circuit output command value Pso is made equal to Pmin ₃ . This means that since the charging rate of the power storage circuit 90 is not sufficient, the engine 11 is operated at the output upper limit value Pgomax, and power is supplied to the power storage circuit 90.

When the storage circuit output target value Psot is between Pmax ₃ and Pmin ₃ , the storage circuit output command value Pso is made equal to the storage circuit output target value Psot. Thereby, the charge rate of the electrical storage circuit 90 can be brought close to the target value of the charge rate.

FIG. 8B shows a case where Pmax ₃ is larger than the storage circuit output upper limit value Psomax determined by the storage circuit output range determination block 33B of FIG. 5 and Pmin ₃ is smaller than the storage circuit output lower limit value Psomin. In this case, the upper and lower limits of the storage circuit output command value Pso are limited so that the storage circuit output command value Pso falls within the appropriate range determined by the storage circuit output range determination block 33B shown in FIG. .

Thus, the upper limit of the storage circuit output command value Pso is limited by the smaller value of Psomax and Pmax _3, and the lower limit is limited by the larger value of Psomin and Pmin ₃ .

  The power command value Psco for turning and the power command value Psbo for boom are obtained from the graph shown in FIG. 6, and the output power command value Pso of the power storage circuit 90 is obtained from the graph shown in FIG. 8A or 8B. . Therefore, the power command value Psao of the assist motor can be calculated based on Equation 4.

The power command value Psao for the assist motor, the power command value Psco for turning, and the power command value Psbo for boom are respectively set to the control output PCa of the assist motor 12, the control output PCc of the turning regenerative motor 21, and the boom regenerative motor. 41 is converted into the control output PCb. When the power command value Psao of the assist motor 12 is positive, that is, when an assist operation is commanded, the efficiency factor ηa ₁ at the time of assist is applied at the time of conversion. When the power command value Psao of the assist motor 12 is negative, that is, when a power generation operation is commanded, the efficiency factor ηa ₂ during power generation is applied during conversion. When the power command value Psco for turning is positive, that is, when a power running operation is commanded, the efficiency factor ηc ₁ during power running is applied during conversion. When the power command value Psco for turning is negative, that is, when a regenerative operation is commanded, the efficiency factor ηc ₂ during regeneration is applied during conversion.

  Control device 30 controls inverters 18, 20, and 40 based on the determined command value.

  Note that the above-described command value determination method is merely an example, and the command value may be determined based on another algorithm. In determining the command value, the hydraulic load output request value Phr, the electric load output request value Peo, the engine speed Nact, and the capacitor voltage Vm are input parameters. When determining the distribution of power and power, it is preferable to convert power and power using the above-described efficiency coefficient. Thereby, the precision of conversion can be improved.

  FIG. 9 shows a flowchart of the efficiency coefficient calibration method. An initial value is set for each efficiency coefficient. For example, the initial value is 1. In step SA1, the assist motor 12 shown in FIG. 2 is assisted. FIG. 10A shows a detailed flowchart of step SA1. First, in step SA11, the engine output upper limit value Pgomax shown in FIG. 5 is set lower than the maximum value of the hydraulic load output request value Phr when the arm 5 is operated as a full stroke alone.

  In step SA12, the arm 5 (FIG. 1) is operated as a single full stroke, and during operation, the transmission / reception power Psa, the drive current Ia, and the rotation speed Na of the assist motor 12 are measured.

Since the arm 5 is operated alone, both the boom load output request value PCbr and the turning load output request value PCcr shown in FIG. For this reason, the power requirement value Pser of the electric load is also zero. In FIG. 6, since the power demand value Pser of the electrical load is 0, the power command value Pseo of the electrical load is also 0. In FIG. 7, since the hydraulic load output request value Phr is positive, the hydraulic load output command value Pho is also positive. 8A or 8B, the hydraulic load output command value Pho when operating the arm 5 alone is larger than the engine output upper limit value Pgomax (Pgomax <Pho), and the electric load power command value Pseo is zero. The power conversion value of the hydraulic load output command value Pho is positive. For this reason, Pmin ₃ in FIG. 8A becomes positive.

  The storage circuit output target value Pbot is determined based on the charging rate SOC. When the charge rate SOC of the power storage circuit 90 matches the target value of the charge rate at the time of starting the single operation of the arm 5, the power storage circuit output target value Pbot becomes zero. During the single operation of the arm 5, the hydraulic load output command value Pho is larger than the engine output upper limit value Pgomax (Pgomax <Pho), so the assist motor 12 is assisted to compensate for the shortage of engine output. .

Since the assist motor 12 is assisted, the charge rate SOC of the power storage circuit 90 decreases. The storage circuit output target value Pbot is set to be negative so that the reduced charging rate SOC is recovered to the target value of the charging rate. Since Pmin _{3 in} FIG. 8A is negative, the storage circuit output command value Pso is positive even if the storage circuit output target value Psot is negative.

  Since both the turning power command value Psco and the boom power command value Psbo are 0 and the storage circuit output command value Pso is positive, the power command value Psao of the assist motor becomes positive from Equation 4. That is, the assist motor 12 is assisted.

In step SA2, an efficiency coefficient ηa ₁ at the time of assist is calculated. Hereinafter, the calculation method will be described.

  In FIG. 4, since the transmission / reception power Psc between the storage circuit 90 and the regenerative motor 21 for turning and the transmission / reception power Psb between the storage circuit 90 and the boom regeneration motor 41 are both 0, the charging / discharging of the capacitor 19 is performed. The power Ps and the transmission / reception power Psa of the assist motor 12 are equal. The charge / discharge power Ps of the capacitor 19 can be calculated from the inter-terminal voltage and the discharge current measured by the capacitor voltmeter 106 and the capacitor ammeter 107 shown in FIG. The calculated output power is equal to the transmission / reception power Psa of the assist motor 12.

  The control output PCa of the assist motor 12 is calculated from the rotation speed Na and the drive current Ia of the assist motor 12. The torque of the assist motor 12 is obtained from the drive current of the assist motor 12 and the torque constant. The power PMa generated by the assist motor 12 is the product of the rotational speed Na of the rotating shaft and the measured value of the generated torque Ta. For calculation of the control output PCa, the drive current of the assist motor 12 is used instead of the actual value of the generated torque Ta.

Since the transmission / reception power Psa of the assist motor 12 and the control output PCa are measured, the efficiency coefficient ηa ₁ at the time of the assist operation is obtained based on Equation 1. Note that it is preferable to employ an average value for a certain period as the charge / discharge power Ps of the capacitor 19 and the control output PCa of the assist motor 12.

  In step SA3, the assist motor 12 is caused to perform a power generation operation, and the drive current Ia, generated power Psa, and rotation speed Na of the assist motor 12 are measured. FIG. 10B shows a detailed flowchart of step SA3.

  In step SA31, the arm 5 is operated by a full stroke alone. After the operation of the arm 5, the transmission / reception power Psa, the drive current Ia, and the rotation speed Na of the assist motor 12 are measured.

  In step SA32, the engine output upper limit value Pgomax is returned to a normal value.

In step SA4, an efficiency coefficient ηa ₂ during power generation is calculated. Hereinafter, a method for calculating the efficiency coefficient ηa ₂ will be described.

  In FIG. 8A or 8B, the hydraulic load output command value Pho becomes the minimum value because the hydraulic pressure is not operated after the single operation of the arm 5 is completed. Therefore, the power conversion value of the engine output upper limit Pgomax is larger than the power conversion value of the hydraulic load output command value Pho. When the arm 5 is operated alone, electric power is supplied from the power storage circuit 90 to the assist motor 12 in order to assist the assist motor 12. For this reason, after completion | finish of single-piece | unit operation of the arm 5, charge rate SOC is falling.

The storage circuit output target value Psot is determined based on the charging rate SOC. That is, the storage circuit output target value Psot is set to be negative in order to recover the charging rate SOC to the target value. For this reason, the storage circuit output command value Pso is also negative. Thereby, the assist motor 12 performs a power generation operation. The power (transmission / reception power) Psa supplied from the assist motor 12 to the capacitor 19 can be measured by the capacitor voltmeter 106 and the capacitor ammeter 107 shown in FIG. The control output PCa of the assist motor 12 can be calculated from the rotation speed Na and the drive current Ia of the assist motor 12. Therefore, based on Formula 1, the efficiency coefficient ηa ₂ during the power generation operation can be calculated.

  In step SA5, the boom 4 is operated as a single full stroke. When the boom 4 is lowered, the boom regenerative motor 41 is regeneratively operated. During the regenerative operation of the boom regenerative motor 41, the charge / discharge power Ps, the drive current Ib, and the rotation speed Nb are measured.

In step SA6, calculates the efficiency factor? B ₂ during regeneration of the boom regenerative motor 41. Hereinafter, a method for calculating the efficiency coefficient ηb ₂ will be described.

  Since the turning operation is not performed, the electric power Psc supplied to the regenerative motor 21 for turning is zero. Therefore, the following formula is established.

The charge / discharge power Ps of the capacitor 19 can be measured by the capacitor voltmeter 106 and the capacitor ammeter 107 shown in FIG. The control output PCa of the assist motor 12 can be calculated from the rotation speed Na of the assist motor 12 and the drive current Ia. The control output PCa is converted into the transmission / reception power Psa of the assist motor 12. When the assist motor 12 is in the assist operation, the efficiency coefficient ηa ₁ at the time of assist is applied, and when the assist motor 12 is in the power generation operation, the efficiency coefficient ηa ₂ at the time of power generation is applied. From these calculated values and Equation 5, the transmission / reception power Psb of the boom regenerative motor 41 is obtained.

Further, the control output PCb of the boom regenerative motor 41 is calculated from the drive current Ib of the boom regenerative motor 41 and the rotation speed Nb. Therefore, the efficiency coefficient ηb ₂ during regeneration of the boom regenerative motor 41 is calculated from Equation 3.

  In step SA7, for example, a reciprocating turning operation of 90 ° is performed. During the turning operation, the turning regenerative motor 21 is powered and regenerated. At this time, the drive current Ic, the rotational speed Nc, and the charge / discharge power Ps of the regenerative motor 21 for turning are measured.

In step SA8, the efficiency coefficient ηc ₁ during power running of the regenerative motor 21 for rotation and the efficiency coefficient ηc ₂ during regeneration are calculated. Hereinafter, a method for calculating the efficiency coefficient ηc ₁ and the efficiency coefficient ηc ₂ will be described.

  Since the boom 4 is not driven, the electric power Psb supplied to the boom regenerative motor 41 is 0 in FIG. Therefore, the following mathematical formula holds.

The charge / discharge power Ps of the capacitor 19 and the transmission / reception power Psc of the assist motor 12 can be calculated as described in step SA6. Therefore, the transmission / reception power Psc of the regenerative motor 21 for rotation can be calculated from Equation 6. The control output PCc of the regenerative motor 21 for rotation can be calculated from the drive current Ic of the regenerative motor 21 for rotation and the rotational speed Nc. The control output PCc and the supplied power Psc are calculated for each of the power running operation and the regenerative operation. The efficiency coefficients ηc ₁ and ηc ₂ can be calculated from these calculated values and Equation 2.

  FIG. 11 shows a flowchart of another method for obtaining efficiency coefficients of the boom regenerative motor 41 and the turning regenerative motor 21.

  In step SB1, the assist motor 12 is turned off. For example, in FIG. 2, the inverter 18 and the power storage circuit 90 are electrically disconnected. For this reason, the transmission / reception power Psa between the assist motor 12 and the storage circuit 90 becomes zero.

In step SB2, the boom 4 is operated as a single full stroke. During operation, transmission / reception power Psb, drive current Ib, and rotation speed Nb of boom regenerative motor 41 are measured. Since the transmission / reception power Psb is equal to the charge / discharge power Ps, the transmission / reception power Psb is determined by measuring the charge / discharge power Ps. In step SB3, the efficiency coefficient ηb ₂ of the boom regenerative motor 41 is calculated. In Equation 5 used in Step SA6 of the method shown in FIG. 9, by setting the transmission / reception power Psa of the assist motor 12 to 0, the efficiency coefficient ηb ₂ can be calculated.

  In step SB4, for example, a reciprocating turning operation of 90 ° is performed. During the turning operation, the turning regenerative motor 21 is powered and regenerated. At this time, the drive current Ic, the rotation speed Nc, and the transmission / reception power Psc of the regenerative motor 21 for turning are measured. The transmission / reception power Psc is equal to the charge / discharge power Ps. Therefore, the transmission / reception power Psc is determined by measuring the charge / discharge power Ps.

In step SB5, the efficiency coefficient ηc ₁ during power running of the regenerative motor 21 for rotation and the efficiency coefficient ηc ₂ during regeneration are calculated. In Equation 6 used in step SA8 of the method shown in FIG. 9, by setting the transmission / reception power Psa of the assist motor 12 to 0, the efficiency coefficients ηc ₁ and ηc ₂ can be calculated.

  In step SB6, the assist motor 12 is returned to the original energized state.

  As described above, by performing efficiency coefficient calibration, power distribution during operation can be performed appropriately.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Hydraulic motor 2 Turning mechanism 3 Upper turning body (2nd external load)
4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 12 Assist motor 13 Torque transmitter 14 Main pump (first external load)
DESCRIPTION OF SYMBOLS 15 Pilot pump 16 High pressure hydraulic line 17 Control valve 18 Inverter 19 Capacitor 21 Revolving motor 22 Resolver 23 Mechanical brake 24 Reduction gear 25 Pilot line 26 Operating device 27, 28 Hydraulic line 29 Pressure sensor 30 Controller 32 Engine output range determination block 33A SOC calculation block 33B Power storage circuit output range determination block 33C Power storage circuit output target value determination block 35 Power distribution block 40 Inverter 41 Boom regenerative motor 42 Boom regenerative hydraulic motor 90 Power storage circuit 100 Converter 101 Reactor 102A Boost IGBT
102B IGBT for step-down
102a, 102b Diodes 103A, 103B Power supply connection terminals 104A, 104B Output terminal 105 Smoothing capacitor 106 Capacitor voltmeter 107 Capacitor ammeter 110 DC bus line 111 DC bus voltmeter

Claims (11)

An engine that generates torque by burning fuel,
An assist motor capable of selectively performing power generation operation and assist operation;
A torque transmission machine for mutually transmitting and receiving torque of the engine and torque of the assist motor;
A power storage circuit that is charged by the power generated by the assist motor and supplies the assist motor by discharging the stored power; and
A first external load that is a mechanical load of the engine;
A second external load which is a mechanical load;
A regenerative motor that applies braking force to the second external load by regenerating power from the second external load;
A control device,
The torque transmission mechanism transmits torque generated by the engine and torque generated by the assist motor to the first external load,
Regenerative power generated by the regenerative motor is supplied to the power storage circuit,
The control device causes the assist motor to perform an assist operation, and measures the charge / discharge power of the power storage circuit, the drive current of the assist motor, and the rotation speed when the assist motor is in an assist operation.
Based on the measured charge / discharge power, the drive current, and the rotational speed, a hybrid type that calculates a first efficiency coefficient indicating a relationship between the transmission / reception power, the drive current, and the rotational speed of the assist motor during the assist operation. Work machine. The control device causes the assist motor to perform a power generation operation, and when the assist motor is in a power generation operation, measures the drive current and rotation speed of the assist motor, and the charge / discharge power of the power storage circuit,
The second efficiency coefficient indicating the relationship between the drive current, rotation speed, and transmission / reception power of the assist motor during power generation operation is calculated based on the measured drive current, rotation speed, and charge / discharge power. 2. A hybrid work machine according to 1. The second external load is a mechanical load driven by the regenerative motor,
The control device includes:
Regenerative operation of the regenerative motor, during regenerative operation, measuring the charge and discharge power of the power storage circuit, measuring the drive current and rotation speed of the regenerative motor,
A third efficiency coefficient indicating a relationship between transmission / reception power, drive current, and rotation speed during the regenerative operation of the regenerative motor is calculated based on the measured charge / discharge power, the drive current, and the rotation speed. Item 3. The hybrid work machine according to Item 2.   When calculating the third efficiency coefficient during the regenerative operation of the regenerative motor, the control device takes into account the first efficiency coefficient or the second efficiency coefficient of the assist motor and regenerates the regenerative motor. The hybrid work machine according to claim 3, wherein the third efficiency coefficient during operation is calculated.   The said control apparatus is a state which does not transmit / receive electric power between the said assist motor and the said electrical storage circuit at the time of the regenerative operation of the said regenerative motor at the time of calculating a said 3rd efficiency coefficient. Hybrid work machine. Furthermore, it has an operating device operated by an operator,
The controller is
Based on the operation amount of the controller device, an output request value for the first external load is calculated,
A command value for power to be output to the first external load is calculated based on the required output value, the output upper limit value of the engine, the output upper limit value of the power storage circuit, and the first efficiency coefficient. Item 6. The hybrid work machine according to any one of Items 1 to 5. An engine that generates torque by burning fuel,
An assist motor capable of selectively performing power generation operation and assist operation;
A torque transmission machine for mutually transmitting and receiving torque of the engine and torque of the assist motor;
A power storage circuit that is charged by the power generated by the assist motor and discharges the stored power to supply power to the assist motor ;
A first external load that is a mechanical load of the engine;
A second external load which is a mechanical load;
Have a <br/> regenerative motor that gives a braking force to an external load of the second by regenerative power from said second external load,
The torque transmission mechanism transmits torque generated by the engine and torque generated by the assist motor to the first external load,
In hybrid working machine regenerative power generated by the regenerative motor Ru is supplied to the storage circuit,
A step of assisting the assist motor, and measuring the charge / discharge power of the power storage circuit, the drive current of the assist motor, and the rotation speed when the assist motor is being assisted.
Calculating a first efficiency coefficient indicating a relationship between the transmission / reception power of the assist motor, the rotation speed, and the drive current during the assist operation based on the measured charge / discharge power, the drive current, and the rotation speed; Of calculating efficiency factor of hybrid work machine having further,
The power generation operation of the assist motor, and when the assist motor is in a power generation operation, measuring the drive current of the assist motor, the rotation speed, and the charge / discharge power of the power storage circuit;
A step of calculating a second efficiency coefficient indicating a relationship between the driving current, the rotational speed, and the transmission / reception power of the assist motor during the power generation operation based on the measured driving current, the rotational speed, and the charge / discharge power. The calculation method of the efficiency coefficient of the hybrid type work machine of Claim 7 which has these. The second external load is a mechanical load driven by the regenerative motor,
The calculation method of the efficiency coefficient further includes:
Regenerating the regenerative motor, and measuring the charge / discharge power of the power storage circuit, the drive current of the regenerative motor, and the number of rotations during the regenerative operation;
A step of calculating a third efficiency coefficient indicating a relationship among transmission / reception power, rotation speed, and drive current during the regenerative operation of the regenerative motor based on the measured charge / discharge power, drive current, and rotation speed. The calculation method of the efficiency coefficient of the hybrid type work machine of Claim 8 which has these. When calculating the third efficiency factor, the driving current of the assist motor, rotational speed, and in consideration of the first or second efficiency factor, to claim 9 configured to calculate the third efficiency factor The calculation method of the efficiency coefficient of the described hybrid type work machine. The hybrid work machine according to claim 9 , wherein power is not transmitted and received between the assist motor and the power storage circuit during the regenerative operation of the regenerative motor when calculating the third efficiency coefficient. Method of calculating the efficiency factor.