JP2010178446A - Hybrid working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress an excessive rise in temperature of a capacitor since the deterioration of the capacitor accelerates if charge and discharge is performed while the capacitor is overheated. <P>SOLUTION: A motor (21) performs power-run operation and regenerative operation. An electrical circuit (20) controls the output of the motor. A capacitor (19) supplies the power with power, and accumulates the regenerative power from the motor. A capacitor charge and discharge circuit (100) controls the charge and discharge current of the capacitor. A temperature detector (36) detects the temperature of the capacitor. Temperature data detected with a temperature detector are input into a controller (30). The capacitor charge and discharge circuit is controlled so that the charge current and discharge current of the capacitor may not surpass second limit values (I<SB>DF</SB>, I<SB>CF</SB>) smaller than first limit values (I<SB>DN</SB>and I<SB>CN</SB>) being usual limit values, when the temperature detected with the temperature detector is a reference temperature (T<SB>1</SB>) or over. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a hybrid work machine that converts kinetic energy or potential energy into electrical energy, stores the electrical energy in a power storage device, and drives a drive system using the stored electrical energy.

  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 the hydraulic pump or as an auxiliary to the hydraulic pump 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. For example, an electric double layer capacitor is used as the capacitor.

  Capacitors deteriorate due to long-term repeated charge / discharge or overcharge, overdischarge, heat generation, or the like. The deterioration state can be determined by measuring the internal resistance of the capacitor (Patent Document 1).

JP 2007-155586 A

  If charging / discharging is performed in a state where the capacitor is overheated, deterioration of the capacitor is accelerated. Further, since the internal resistance of the capacitor becomes high at a low temperature, it is not preferable to perform normal charging / discharging at a low temperature.

According to one aspect of the invention,
A first electric motor that performs a power running operation driven by the supply of electric power and a regenerative operation that generates electric power;
A first electric circuit for controlling the output of the first electric motor;
A capacitor for supplying electric power to the first electric motor and storing regenerative electric power from the first electric motor;
A capacitor charge / discharge circuit for controlling a charge / discharge current of the capacitor;
A temperature detector for detecting the temperature of the capacitor;
When the temperature data detected by the temperature detector is input and the temperature detected by the temperature detector is equal to or higher than a first reference temperature, the charging current and discharging current of the capacitor are limited to normal values. There is provided a hybrid work machine having a control device for controlling the capacitor charge / discharge circuit so as not to exceed a second limit value smaller than the first limit value.

  Further temperature rise of the capacitor can be suppressed. Thereby, deterioration of the capacitor is suppressed.

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 converter used for the hybrid type working machine by an Example. It is a state transition diagram of the driving | running state of the hybrid type working machine by an Example. It is a timing chart which shows the example which will be in the 1st high temperature abnormal state. It is a timing chart which shows the example which becomes the 2nd high temperature abnormal state. It is a timing chart which shows the example which will be in a low temperature abnormal state.

  FIG. 1 is 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 the input shaft of the speed reducer 13. As the engine 11, an engine that generates a driving force by a fuel other than electricity, for example, an internal combustion engine such as a diesel engine is used. The engine 11 is always driven during operation of the work machine.

  The drive shaft of the motor generator 12 is connected to the other input shaft of the speed reducer 13. The motor generator 12 can perform both the electric (assist) operation and the power generation operation. As the motor generator 12, for example, an internal magnet embedded (IMP) motor in which magnets are embedded in the rotor is used.

  The speed reducer 13 has two input shafts and one output shaft. A drive shaft of the main pump 14 is connected to the output shaft.

  When the load applied to the engine 11 is large, the motor generator 12 performs an assist operation, and the driving force of the motor generator 12 is transmitted to the main pump 14 via the speed reducer 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 driving force of the engine 11 is transmitted to the motor generator 12 via the speed reducer 13 so that the motor generator 12 is in a power generation operation. Switching between the assist operation and the power generation operation of the motor generator 12 is performed by an inverter 18 connected to the motor generator 12. The inverter 18 is controlled by the control device 30.

  The control device 30 includes a central processing unit (CPU) 30A and an internal memory 30B. The CPU 30A executes a drive control program stored in the internal memory 30B. 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 1A, 1B, the boom cylinder 7, the arm cylinder 8, and the packet cylinder 9 in accordance with 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 motor generator 12 is connected to the storage circuit 90 via the inverter 18. The inverter 18 controls the operation of the motor generator 12 based on a command from the control device 30. Further, a turning electric motor 21 is connected to the storage circuit 90 via another inverter 20. The storage circuit 90 and the inverter 20 are controlled by the control device 30.

  During the period in which the motor generator 12 is assisted, necessary electric power is supplied from the power storage circuit 90 to the motor generator 12. During the period in which the motor generator 12 is generating, the electric power generated by the motor generator 12 is supplied to the storage circuit 90.

  The turning electric motor 21 is AC driven by a pulse width modulation (PWM) control signal from the inverter 20 and can perform both a power running operation and a regenerative operation. For example, an IMP motor is used for the turning electric motor 21. The IMP motor generates a large induced electromotive force during regeneration.

  During the power running operation of the turning electric motor 21, the rotational force of the turning electric motor 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 rotational force generated by the turning electric motor 21 increases and is transmitted to the turning mechanism 2. Further, during regenerative operation, the rotational motion of the upper swing body 3 is transmitted to the turning electric motor 21 via the speed reducer 24, so that the turning electric motor 21 generates regenerative power. At this time, the speed reducer 24 increases the rotation speed, contrary to the power running operation. Thereby, the rotation speed of the electric motor 21 for rotation can be raised.

  The resolver 22 detects the position of the rotation shaft of the turning electric motor 21 in the rotation direction. 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 the operation of the turning electric motor 21, the turning angle and the turning direction are derived.

  A mechanical brake 23 is connected to the rotating shaft of the turning electric motor 21 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. In particular, in the hybrid work machine according to the embodiment, not only the hydraulic motors 1A and 1B but also the turning electric motor 21 drives the turning mechanism 2. For this reason, it is desirable to detect the operation amount of the lever for controlling the turning mechanism 2 with high accuracy. The control device 30 can detect the operation amount of the lever with high accuracy via the pressure sensor 29.

  Further, in the control device 30, none of the lower traveling body 1, the turning mechanism 2, the boom 4, the arm 5, and the bucket 6 is operated, and the power supply to the power storage circuit 90 and the power from the power storage circuit 90 are It is possible to detect a state where no forced removal is performed (non-operating state).

  FIG. 3 shows an equivalent circuit diagram of the power storage circuit 90. The storage circuit 90 includes a capacitor 19, a converter 200, 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 motor generator 12 and the turning electric motor 21 via inverters 18 and 20. 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 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. An 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 temperature detector 36 detects the temperature of the capacitor 19. The detected temperature data is input to the control device 30. The capacitor 19 includes, for example, 144 electric double layer capacitors connected in series. The temperature detector 36 includes, for example, four thermometers prepared corresponding to four capacitors selected from 144 electric double layer capacitors. For example, the control device 30 calculates an average of four temperature data acquired by four thermometers, and sets the average value as the temperature of the capacitor 19. When determining the overheating state of the capacitor, the highest temperature among the temperatures indicated by the four temperature data may be adopted as the capacitor temperature. On the other hand, the lowest temperature among the temperatures indicated by the four temperature data may be adopted as the capacitor temperature for determining the state in which the temperature of the capacitor is excessively lowered.

  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.

  The control device 30 includes an internal memory 30B. A charge / discharge current limit value storage unit 31 and a turning output limit value storage unit 32 are secured in the internal memory 30B. These roles will be described later with reference to FIGS.

  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.

In FIG. 4, an example of the transition diagram of the driving | running state controlled by the control apparatus 30 is shown. The operating state normally includes five states of low temperature abnormality, first high temperature abnormality, second high temperature abnormality, and waiting for recovery from high temperature abnormality. During operation in the normal state, when the capacitor temperature reaches the first reference temperature above T _1, the operating state transitions to the first high temperature abnormality condition. During operation in the first high temperature abnormality condition, if the capacitor temperature is lowered to lower high temperature abnormality recovery temperature T _HR than the first reference temperature T _1, the operating state returns to a normal state.

If the capacitor temperature becomes equal to or higher than the second reference temperature T ₂ higher than the first reference temperature T ₁ during operation in the first high temperature abnormal state, the operation state transitions to the second high temperature abnormal state. During operation in the second high temperature abnormality condition, if the capacitor temperature is lowered to a second reference temperature T _2, the operating state transitions to high temperature abnormality recovery waiting state. During operation at high temperature abnormality recovery waiting state, when the operator operates the recovery instruction, it compares the magnitude of the reference temperature T ₁ of the capacitor temperature and the first of the current. When the capacitor temperature is equal to or higher than the _first reference temperature T1, the operating state transitions to the first high temperature abnormal state. When the capacitor temperature is lower than the first reference temperature T ₁ of the operating state returns to the normal state. The operation of the recovery instruction is performed by the operation device 26 shown in FIG.

When the high temperature abnormality recovery waiting state, when the capacitor temperature reaches the second reference temperature T ₂ higher again, it returns to the second high temperature abnormality condition.

During operation in the normal state, the capacitor temperature is, when the first reference temperature T ₁ of the third reference temperature T ₃ less since lower than, the operating state transitions to a low temperature abnormal state. If the capacitor temperature becomes _{equal to} or higher than the low temperature abnormality recovery temperature _TLR during operation in the low temperature abnormality state, the operation state returns to the normal state.

  FIG. 5 shows an example of a timing chart in the case where the operation state returns to the normal state after the normal state is changed to the first high temperature abnormal state.

In the top row, the temperature of the capacitor 19 detected by the temperature detector 19 is shown. The temperature of the capacitor 19 rises with time, the time t _1, more than a first reference temperature T _1. When the capacitor temperature exceeds the first reference temperature T _1, as shown in FIG. 4, the operating state is changed from the normal state to the first high temperature abnormality condition.

Capacitor temperature, without reaching the second reference temperature T _2, at time t _2, the drop to high temperature abnormality recovery temperature T _HR. In time t _2, the operating state returns to a normal state from the first high temperature abnormality condition. By setting the high temperature abnormal recovery temperature T _HR lower than the first reference temperature T _1, it is possible to prevent repeated short-cycle transitions between the first high temperature abnormal state and the normal state. Can do.

  In the second stage, the operation command state of converter 100 is shown. “ON” indicates that converter 100 is in an operating state, and “OFF” indicates that converter 100 is in a stopped state. In the operating state, a predetermined PWM voltage is applied to the gate electrodes of the step-up IGBT 102A and the step-down IGBT 102B shown in FIG. In the stop state, the step-up IGBT 102A and the step-down IGBT 102B shown in FIG. 3 are always non-conductive.

An example of the charge / discharge current measured by the ammeter 107 shown in FIG. I _DF and I _{CF on the} vertical axis indicate the limit values of the discharge current and the charge current at the time of abnormality, respectively, and I _DN and I _CN indicate the limit values of the discharge current and the charge current at the normal time, respectively. These limit values are stored in the charge / discharge current limit value storage unit 31 shown in FIG. Although the direction of the charging current is defined as negative, the charging current limit values I _CN and I _CF represent the magnitude of the current. For this reason, in the chart shown in FIG. 4, the charging current limit values I _CN and I _CF are assigned minus signs. The charging current limit value I _CF at the time of abnormality is smaller than the charging current limit value I _CN at the normal time. Limit value I _DF of abnormal discharge current is smaller than the limit value I _DN of discharge current in normal.

  Control device 30 controls converter 100 such that the charge / discharge current does not exceed the currently effective limit value.

When the operation state is the normal state, that is, between time 0 and t ₁ and after time t ₂ , the normal limit value I _DN is effective as the discharge current limit value of the capacitor 19, and the charge current limit value As a result, the normal limit value I _CN becomes valid. Which limit value is valid is determined by the control device 30. When the operation state is the first high-temperature abnormal state, that is, during the period from time t ₁ to t ₂ , the high-temperature abnormal limit value I _DF is made effective as the limit value of the discharge current of the capacitor 19 to limit the charging current As a value, the high temperature abnormal limit value _ICF is made effective.

  The charge / discharge current actually flows in a pulsed manner by the induced electromotive force generated in the reactor 101 shown in FIG. Strictly speaking, “the magnitude of the charge / discharge current” means the time average value of the current flowing in a pulse manner. The magnitude of the charge / discharge current is actually controlled by changing the frequency of the PWM voltage applied to the gate electrodes of the step-up IGBT 102A and the step-down IGBT 102B shown in FIG.

  By making the smaller limit value valid as the limit value of the charge / discharge current in the first high temperature abnormal state, heat generation from the capacitor 19 can be suppressed. Thereby, the further temperature rise of the capacitor 19 is suppressed.

In the fourth row, an example of the output of the engine 11 is shown. Limit value P _E in normal time and the first high-temperature abnormality of the engine 11 are the same. Controller 30 controls the engine 11 so that the output of the engine 11 does not exceed the limit value P _E.

On the fifth level, an example of the output of the turning electric motor 21 is shown. P _CN and P _CF of ordinate indicate respectively the normal time limits and the high-temperature abnormality limit. The high temperature abnormal limit value _PCF is smaller than the normal limit value _PCN .

The control device 30 controls the inverter 20 so that the output of the turning electric motor 21 does not exceed the current effective limit value. When the operation state is the normal state, the normal limit value _PCN is validated, and when the operation state is the first high temperature abnormality state, the high temperature abnormality limit value _PCF is validated.

  The turning electric motor 21 is driven by electric power generated by the motor generator 12 and electric power discharged from the capacitor 19. Corresponding to the fact that the limit value of the discharge current of the capacitor 19 is small in the first high temperature abnormal state, the limit value of the output of the turning electric motor 21 is made low. This prevents an excessive electrical load from being applied during the power generation operation of the motor generator 12.

In the sixth stage, an example of hydraulic output is shown. Limit value P _P of the hydraulic output is constant irrespective of the normal state and the first high temperature abnormality condition. During the period of the first high temperature abnormal state, the output of the assist operation due to the discharge from the capacitor 19 is restricted, but by increasing the output of the engine 11, a necessary hydraulic output can be obtained. Therefore, even when the first high temperature abnormality condition, it is not necessary to reduce the limit value P _P of the hydraulic output.

  In the seventh row, the display state of the display device 35 is shown. “Normal” is displayed in the normal state, and “Abnormal 1” is displayed in the first high temperature abnormal state. The operator can recognize the current driving state by visually recognizing this display.

FIG. 6 shows an example of a timing chart when the second high temperature abnormal state is reached. Similarly to FIG. 6, the first to seventh charts are charts of capacitor temperature, converter operation command, charge / discharge current, engine output, turning motor output, hydraulic output, and display output, respectively. . At time t _1, capacitor temperature exceeds the first reference temperature T _1, the operating condition is changes to the first high temperature abnormality condition. Then, at time t _3, the capacitor temperature is greater than the second reference value T _2, the operating state transitions to the second high temperature abnormality condition.

  When the operation state becomes the second high temperature abnormality state, the converter operation command is “OFF”. That is, the step-up IGBT 102A and the step-down IGBT 102B shown in FIG. For this reason, forced charging and discharging based on the induced electromotive force of the reactor 101 are not performed. When the voltage between the output terminals 104A and 104B is lower than the voltage between the terminals of the capacitor 19, a discharge current of the capacitor 19 flows through the diode 102b.

As limit values of the charge / discharge current, effective limit values I _DF and I _{CF at} the time of the first high temperature abnormal state are maintained. However, since the converter operation command is “OFF”, almost no charge / discharge current flows.

The engine output and hydraulic output limit values _PE and _PP are the same as the limit values in the normal state. As the limit value of the output of the turning electric motor, limit value P _CF when the first high temperature abnormality state is maintained. Since the forced discharge from the capacitor 19 is not performed, the turning electric motor 21 is driven by the electric power generated by the electric power generation operation of the motor generator 12. Further, the assist operation of the motor generator 12 is not performed.

  When the second high temperature abnormality state is reached, “abnormality 2” is displayed on the display device.

  In the second abnormal state of high temperature, the capacitor 19 is hardly charged / discharged. Therefore, the increase in the temperature of the capacitor 19 is suppressed, and further the temperature starts to decrease.

At time t _4, when the temperature of the capacitor 19 becomes the second reference temperature T ₂ less, as shown in FIG. 4, a transition to a state of high temperature abnormality recovery waiting. In addition, “waiting for recovery” is displayed on the display device.

At time t _5, when the operator operates the recovery instructions, along with converter operation command is "ON", the operating state transitions. In Figure 6, for the capacitor temperature during operation of the recovery instruction is first standard temperature above T _1, the operating state transitions to the first high temperature abnormality condition. Incidentally, the capacitor temperature during operation of the recovery instruction if less than a first reference temperature T ₁ of the operating state as shown in FIG. 4 transitions to the normal state. At time t _6, when the capacitor temperature is below high temperature abnormality recovery temperature T _HR, the operating condition is restored to the normal state.

  Since the capacitor 19 is not forcibly charged and discharged in the second high temperature abnormal state, further temperature rise of the capacitor 19 can be suppressed. Thereby, deterioration of the capacitor 19 can be suppressed.

  FIG. 7 shows an example of a timing chart when a low temperature abnormality state is reached. A chart of capacitor temperature, converter operation command, charge / discharge current, engine output, turning motor output, hydraulic output, motor generator output, and display device output is shown in order from the top.

Capacitor temperature at the start of operation is to be a third reference temperature T ₃ below. At this time, the operating state is a low temperature abnormal state. The converter operation command is “ON”. I _CFL and I _DFL on the vertical axis of the charge / discharge current chart indicate a charge current limit value at a low temperature and a discharge current limit value at a low temperature, respectively. The charging current limit value I _CFL at low temperature is smaller than the charging current limit value I _CN at normal time, and the discharging current limiting value I _DFL at low temperature is smaller than the limiting value I _DN at normal temperature. In the case of a low tone abnormal state, limit values I _CFL and I _DFL at the time of low temperature abnormality are made valid.

P _CFL of the vertical axis of the turning electric motor output chart indicates the output limit value at the low temperature abnormality. When the temperature is abnormal, the output limit value _PCFL at the time of low temperature is made effective. “Low temperature abnormality” is displayed on the display device.

_PAF and _PGF on the vertical axis of the chart indicating the motor generator output indicate an assist operation output limit value and a power generation operation output limit value when the temperature is abnormal. _PAN and _{PGN on the} vertical axis indicate the assist operation output limit value and the power generation operation output limit value in normal times, respectively. The control device 30 controls the inverter 18 so that the assist operation and the power generation operation are performed within a range not exceeding the currently effective limit value.

When it is in the low temperature abnormality state and the turning electric motor 21 is not driven, the low temperature abnormality limit values _PAF and _PGF are validated, and the assist operation and the power generation operation are repeated alternately. Controls the inverter 18. Since no electric power is supplied to the turning motor 21 and no regenerative power is extracted from the turning motor 21, a discharge current flows through the capacitor 19 during the assist operation of the motor generator 12, and a charging current flows during the power generation operation. The charging current and the discharging current generate heat in the capacitor 19. Thereby, the temperature of the capacitor 19 can be raised.

At time t _10, the capacitor temperature is equal to or higher than the low temperature abnormality recovery temperature T _LR than the third reference temperature, the operating state transitions to the normal state. The normal limit values I _DN and I _CN are validated as limit values for the charge / discharge current, the normal limit value P _CN is validated as the limit value for the turning motor output, and the motor generator output assist operation output In addition, the normal limit values _PAN and _PGN are validated as the limit values of the power generation operation output. The operation of the motor generator 12 also returns to the normal operation. That is, the assist operation or the power generation operation is switched according to the load.

For some reason, when the capacitor temperature at time t ₁₂ is the third reference temperature T ₃ below, the operating state transitions to a low temperature abnormal state. As each limit value, the limit value at low temperature abnormality is made effective. The assist operation and the power generation operation of the motor generator 12 are switched according to the operation of the turning electric motor 21 and the charge / discharge operation of the capacitor 19. By reducing the limit value of the charge / discharge current, it is possible to prevent a large current from flowing while the internal resistance of the capacitor 19 is high.

At time t _12, when the capacitor temperature becomes higher cold abnormality recovery temperature T _LR, the operating condition is restored to the normal state.

  In the above embodiment, the case where the operation command of the converter 100 is “ON” in the normal state has been described, but the operation command of the converter 100 may be “OFF”. Also in this case, each limit value becomes effective according to the operating state, as in the case of the above embodiment.

  When the operation command of the converter 100 is “OFF”, a discharge current may flow from the capacitor 19 via the diode 102b shown in FIG. The control for limiting the magnitude of the discharge current is performed by limiting the total value of the outputs of the motor generator 12 and the turning electric motor 21 shown in FIG. Specifically, the upper limit of the total output of the motor generator 12 and the turning electric motor 21 is set so that the magnitude of the discharge current flowing through the converter 100 falls within the range of the limit value currently effective. Calculate the value. The inverters 18 and 20 are controlled so that the total output of the motor generator 12 and the turning electric motor 21 does not exceed this upper limit value.

  In the above-described embodiment, the excavator that performs the regenerative operation of the turning electric motor 21 has been described as the hybrid work machine. The method for controlling the power storage circuit 90 described in the above embodiment can also be applied to a crane provided with a winding drive device. In this case, the potential energy of the winding symmetrical object is converted into electric energy. The generated electrical energy is stored in the capacitor 19. During the winding operation, the hoisting motor is driven by the discharge current from the capacitor 19 and the generated power from the motor generator 12.

  In addition, the method for controlling the storage circuit 90 described in the above embodiment can also be applied to a lifting magnet type work machine. In this case, the lifting magnet is attracted by the discharge current from the capacitor 19.

  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.

1 Lower traveling body (base)
1A, 1B Hydraulic motor 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 (second motor)
13 Reducer 14 Main pump 15 Pilot pump 16 High pressure hydraulic line 17 Control valve 18 Inverter (second electric circuit)
19 Capacitor 20 Inverter (first electric circuit)
21 Electric motor for turning (first electric motor)
22 resolver 23 mechanical brake 24 speed reducer 25 pilot line 26 operation device 27, 28 hydraulic line 29 pressure sensor 30 control device 35 display device 36 temperature detector 100 converter (capacitor charge / discharge circuit)
101 Reactor 102A Boost IGBT
102B IGBT for step-down
102a, 102b Diodes 103A, 103B Power connection terminals 104A, 104B Output terminal 105 Smoothing capacitor 106 Voltmeter 107 Ammeter 111 Voltmeter

Claims (7)

A first electric motor that performs a power running operation driven by the supply of electric power and a regenerative operation that generates electric power;
A first electric circuit for controlling the output of the first electric motor;
A capacitor for supplying electric power to the first electric motor and storing regenerative electric power from the first electric motor;
A capacitor charge / discharge circuit for controlling a charge / discharge current of the capacitor;
A temperature detector for detecting the temperature of the capacitor;
When the temperature data detected by the temperature detector is input and the temperature detected by the temperature detector is equal to or higher than a first reference temperature, the charging current and discharging current of the capacitor are limited to normal values. And a control device that controls the capacitor charge / discharge circuit so as not to exceed a second limit value smaller than the first limit value.   When the temperature detected by the temperature detector becomes equal to or higher than the first reference temperature, the control device further outputs the output of the first electric motor from a third limit value that is a limit value at normal time. 2. The hybrid work machine according to claim 1, wherein the first electric circuit is controlled so as not to exceed a smaller fourth limit value. further,
A substrate;
A swivel body pivotably attached to the base body,
3. The hybrid work machine according to claim 1, wherein the first electric motor generates a rotational driving force for turning the turning body. 4.   When the temperature detected by the temperature detector is equal to or lower than a first recovery temperature lower than the first reference temperature, the control device sets the limit values of the charging current and discharging current of the capacitor at a normal time. The hybrid work machine according to any one of claims 1 to 3, wherein the capacitor charge / discharge circuit is controlled by returning to a value of.   When the temperature detected by the temperature detector is equal to or higher than a second reference temperature higher than the first reference temperature, the control device charges the capacitor and forcibly discharges the capacitor. The hybrid type work machine according to any one of claims 1 to 4, wherein the capacitor charge / discharge circuit is controlled so as to stop the operation.   When the control device detects that the temperature detected by the temperature detector is equal to or lower than a third reference temperature lower than the first reference temperature, the charging current and discharging current of the capacitor are normally The capacitor charge / discharge circuit is controlled so that the sixth limit value smaller than the fifth limit value, which is the limit value at the time, is not exceeded, and the output of the first electric motor is the normal limit value. The hybrid work machine according to any one of claims 1 to 5, wherein the first electric circuit is controlled so as not to exceed an eighth limit value smaller than a seventh limit value. further,
An engine that generates driving force using fuel other than electricity;
A power generation operation that is mechanically connected to the drive shaft of the engine and is electrically connected to the capacitor and is driven by the engine to generate electric power, and mechanical driving force by being supplied with electric power from the capacitor A second electric motor for performing an assist operation for assisting the driving force of the engine by generating
A second electric circuit that switches between a state in which electric power is supplied to the second electric motor and a state in which generated electric power is taken out from the second electric motor;
When the temperature detected by the temperature detector becomes equal to or lower than the third reference temperature, the control device causes the second motor to alternately repeat a power generation operation and an assist operation. The hybrid type work machine according to claim 6 which controls an electric circuit.

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