JP5982317B2 - Charge control device and hybrid construction machine - Google Patents

Description

  The present invention relates to a charge control device that controls charging of a secondary battery and a hybrid construction machine.

  As a conventional charge control device, Patent Document 1 discloses a system in which a secondary battery is charged by heating with a heater when the temperature of the secondary battery is lower than a set temperature.

JP 2007-330008 A

  In a system as disclosed in Patent Document 1, when a secondary battery is charged at a low temperature lower than 0 ° C., the secondary battery may be deteriorated. Therefore, when charging the secondary battery at a low temperature, for example, when the temperature is lower than 0 ° C., the secondary battery is charged at a charge rate of 0.3 C rate or less. However, in this case, since the charging rate of the secondary battery is lowered, there is a problem that the time required for charging becomes long.

  The present invention has been made in view of the above problems, and an object thereof is to shorten the time required for charging a secondary battery at a low temperature.

  The present invention provides a determination unit that determines whether a temperature of the secondary battery is lower than a deterioration threshold value for preventing the deterioration of the secondary battery, and the determination unit determines that the temperature of the secondary battery is lower than the deterioration threshold value If it is determined that the charging rate is low, the secondary charging is intermittently performed so that the average value of the charging rate is larger than the upper limit value of the charging rate at which deterioration due to continuous charging can be avoided at a temperature lower than the deterioration threshold. And an intermittent charge control unit for charging the battery.

  In the present invention, the secondary battery is intermittently charged at a low temperature lower than the deterioration threshold, thereby charging the secondary battery at a higher charge rate than when continuously charging at a low temperature. Can be fully charged. Therefore, the time required for charging the secondary battery at a low temperature can be shortened.

It is a side view which shows the outline | summary of the excavation attachment of a hydraulic shovel. It is a block diagram which shows the outline | summary of the fluid pressure control apparatus which concerns on embodiment of this invention. It is a block diagram which shows the outline | summary of the assist regeneration mechanism connected to a fluid pressure control apparatus. It is a functional block diagram which shows the detailed structure of a controller. It is a flowchart which shows the charge control method of the battery by a controller. It is a figure which shows the waveform of the charging current by intermittent charge at the time of low temperature, and continuous charge. It is a figure which shows the deterioration characteristic of the intermittent charge at the time of low temperature, and continuous charge.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The charge control device is mounted on a hydraulic working device such as a hydraulic excavator, for example. In the present embodiment, the charge control device includes a fluid pressure control device that controls the operation of the hydraulic excavator.

  First, with reference to FIG. 1, the expansion / contraction operation | movement of the boom cylinder 104 which drives the boom 101 of the hydraulic shovel which concerns on this embodiment is demonstrated.

  The excavation attachment 100 drives a boom 101, an arm 102, and a bucket 103 provided to perform excavation work, a boom cylinder 104 that drives the boom 101, an arm cylinder 105 that drives the arm 102, and the bucket 103. A bucket cylinder 106.

  The boom cylinder 104 is an actuator that drives the boom 101, the arm 102, and the bucket 103. Each of the boom cylinder 104, the arm cylinder 105, and the bucket cylinder 106 is a hydraulic cylinder.

  FIG. 2 is a system diagram showing a main configuration of the fluid pressure control device 120 according to the present embodiment.

  The fluid pressure control device 120 includes a main pump 108, a pilot pump 109, a main control valve 110, a main passage 111, a first passage 112, a second passage 113, and a controller 114.

  The boom cylinder 104 is divided into a rod-side pressure chamber 104a and a bottom-side pressure chamber 104b by a piston rod 107 that slidably moves within the boom cylinder 104. The piston rod 107 is connected to the boom 101, and the boom 101 is driven when the piston rod 107 moves in the boom cylinder 104.

  The main pump 108 is a main fluid pressure pump that drives the boom cylinder 104, the arm cylinder 105, and the bucket cylinder 106.

  The pilot pump 109 is a hydraulic pump that supplies pilot pressure to the pilot chambers 110a and 110b.

  The main pump 108 and the pilot pump 109 are driven by an engine (not shown) mounted on a hydraulic excavator, and discharge hydraulic oil (working fluid). The main pump 108 and the pilot pump 109 are variable displacement hydraulic pumps capable of controlling the discharge amount of hydraulic oil by controlling the inclination angle of the swash plate. The engine is operated at a predetermined rotational speed and load with good operating efficiency.

  The hydraulic oil discharged from the main pump 108 is supplied to a main control valve 110 that switches between supplying and discharging hydraulic oil to and from the boom cylinder 104. The main pump 108 and the main control valve 110 are connected by a main passage 111. In addition to the hydraulic oil discharged from the main pump 108, the hydraulic oil discharged from the assist pump 3 of the assist regeneration mechanism 10 (see FIG. 3), which will be described later, is guided to the main passage 111 through the sub passage 31.

  The main control valve 110 and the rod side pressure chamber 104a of the boom cylinder 104 are connected to the first passage 112, and the main control valve 110 and the bottom side pressure chamber 104b of the boom cylinder 104 are connected to the second passage 113. . The hydraulic oil discharged from the bottom pressure chamber 104b of the boom cylinder 104 flows through the second passage 113. Moreover, the 2nd channel | path 113 is connected with the return channel | path 21 through which the hydraulic fluid for driving the regeneration motor 2 of the assist regeneration mechanism 10 (refer FIG. 3) mentioned later flows.

  The main control valve 110 is operated by a pilot pressure supplied from the pilot pump 109 to the pilot chambers 110a and 110b. The pilot pressure supplied to the pilot chambers 110a and 110b is adjusted by the controller 114 controlling the pilot solenoid valve 115 based on the lever operation by the crew of the excavator.

  When the pilot pressure is supplied to the pilot chamber 110a, the main control valve 110 is switched to the position a. In this case, the hydraulic oil is supplied from the main pump 108 to the rod side pressure chamber 104a via the first passage 112, and the hydraulic oil in the bottom side pressure chamber 104b is supplied to the tank T via the second passage 113. Discharged. As a result, the piston rod 107 in the boom cylinder 104 moves downward in FIG. 2, that is, the boom cylinder 104 contracts, and the boom 101 descends in the direction of the arrow 121 shown in FIG.

  Further, when the pilot pressure is supplied to the pilot chamber 110b, the main control valve 110 is switched to the position b. In this case, the hydraulic oil is supplied from the main pump 108 to the bottom side pressure chamber 104b through the second passage 113, and the hydraulic oil in the rod side pressure chamber 104a is supplied to the tank T through the first passage 112. Discharged. As a result, the piston rod 107 in the boom cylinder 104 moves upward in FIG. 2, that is, the boom cylinder 104 extends, and the boom 101 rises in the direction of the arrow 122 shown in FIG.

  Further, when the pilot pressure is not supplied to the pilot chambers 110a and 110b, the main control valve 110 is switched to the position c. In this case, the supply and discharge of the hydraulic oil to and from the boom cylinder 104 is interrupted, and the hydraulic oil is supplied from the main pump 108 to the return passage 2 via the second passage 113 while the boom 101 is kept stopped. Thereby, hydraulic fluid flows into the regeneration motor 2 of the assist regeneration mechanism 10 (refer FIG. 3) mentioned later, and the regeneration motor 2 drives.

  In this way, the main control valve 110 is switched to three stages: a contracted position a for contracting the boom cylinder 104, an extended position b for extending the boom cylinder 104, and a holding position c for holding the load of the boom cylinder 104.

  In the present embodiment, the assist regeneration mechanism 10 is connected to the fluid pressure control device 120. The assist regenerative mechanism 10 applies a regenerative operation for recovering hydraulic energy of hydraulic oil discharged from the bottom-side pressure chamber 104b as electric energy when the boom cylinder 104 is contracted, and an auxiliary force when the boom cylinder 104 is extended. Assist operation to be performed as necessary. A hydraulic work device such as a hydraulic excavator in which the operation of the actuator is controlled by the assist regeneration mechanism 10 and the fluid pressure control device 120 is referred to as a hybrid construction machine.

  FIG. 3 is a schematic configuration diagram of the assist regeneration mechanism 10 connected to the fluid pressure control device 120.

  The assist regeneration mechanism 10 includes a motor generator 1, a regeneration motor 2, an assist pump 3, a return passage 21, a sub passage 31, a power storage device 40, a switch circuit 42, and an inverter 50. The power storage device 40 includes a battery 4 and a battery management unit 41.

  The motor generator 1 is a rotating electrical machine having a function as an electric motor driven by the battery 4 and driving the assist pump 3 and a function as a generator generating electric power by being driven by the regenerative motor 2. Motor generator 1 is connected to assist pump 3 via regenerative motor 2. The rotation shafts of the motor generator 1, the regenerative motor 2 and the assist pump 3 are arranged coaxially. When the rotation shaft of the motor generator 1 rotates, the rotation shafts of the regenerative motor 2 and the assist pump 3 rotate together. To do. Similarly, when the rotating shaft of the regenerative motor 2 rotates, the rotating shafts of the motor generator 1 and the assist pump 3 rotate together.

  The regenerative motor 2 is a variable displacement hydraulic motor capable of controlling the output torque by adjusting the inclination angle of the swash plate. The regenerative motor 2 is connected to the assist pump 3. The regenerative motor 2 is driven by the hydraulic oil discharged from the bottom pressure chamber 104b of the boom cylinder 104 and flowing through the return passage 21. Control of the tilt angle of the swash plate of the regenerative motor 2 is performed by the controller 114 controlling the tilt angle controller 24. The rotation of the regenerative motor 2 is controlled by controlling the inclination angle of the swash plate of the regenerative motor 2. Then, the capacity changes according to the rotation of the regenerative motor 2, and the maximum value of torque that can be generated by the regenerative motor 2 changes.

  The return passage 21 is provided with a return control valve 22 that switches between supply and discharge of hydraulic fluid to the regenerative motor 2. The return control valve 22 has a communication position d for supplying hydraulic oil to the regenerative motor 2 according to the pilot pressure supplied from the pilot pump 109 to the pilot chamber 22a, and a shut-off for stopping the supply of hydraulic oil to the regenerative motor 2. Switch to position e. Control of the pilot pressure supplied to the pilot chamber 22a is performed by the controller 114 controlling the pilot solenoid valve 23 based on a lever operation by a crew of the hydraulic excavator.

  The assist pump 3 is a sub-fluid pressure pump that assists driving of these actuators when the main pump 108 drives the boom cylinder 104, the arm cylinder 105, and the bucket cylinder 106. The assist pump 3 is realized by a variable displacement hydraulic pump capable of controlling the discharge amount by controlling the inclination angle of the swash plate.

  The assist pump 3 is driven by the motor generator 1 and supplies hydraulic oil to the main passage 111 via the sub passage 31. Control of the tilt angle of the swash plate of the assist pump 3 is performed by the controller 114 controlling the tilt angle controller 34. By controlling the inclination angle of the swash plate of the assist pump 3, the capacity of the assist pump 3 changes, and the maximum value of the flow rate of hydraulic oil that can be discharged by the assist pump 3 changes.

  The sub passage 31 is provided with a sub control valve 32 that switches supply and discharge of hydraulic oil to and from the main passage 111. The sub control valve 32 has a communication position f for supplying hydraulic oil to the main passage 111 according to the pilot pressure supplied from the pilot pump 109 to the pilot chamber 32a, and a cutoff for stopping the supply of hydraulic oil to the main passage 111. Switching to position g. Control of the pilot pressure supplied to the pilot chamber 32a is performed by the controller 114 controlling the pilot solenoid valve 33 based on a lever operation by the crew of the excavator.

  Motor generator 1 is connected to battery 4 via inverter 50. The motor generator 1 converts the rotational force of the regenerative motor 2 by the main pump 108 into electric power.

  Inverter 50 converts the electric power converted by motor generator 1 from alternating current to direct current, and charges battery 4. Inverter 50 converts the power of battery 4 from direct current to alternating current, and drives motor generator 1. The inverter 50 includes a semiconductor switch 511 such as an IGBT (Insulated Gate Bipolar Transistor) and a smoothing capacitor 52.

  The semiconductor switch 511 is controlled to be opened and closed by the controller 114, so that direct current is converted into alternating current or alternating current is converted into direct current. Specifically, when the motor generator 1 is caused to function as an electric motor, the DC voltage from the battery 4 is converted into a three-phase AC voltage having an arbitrary frequency by the semiconductor switch 511 and supplied to the motor generator 1. That is, the inverter 50 outputs a discharge current from the battery 4 to the motor generator 1.

  On the other hand, when the motor generator 1 functions as a generator, the three-phase AC voltage from the motor generator 1 is converted into a DC voltage by the semiconductor switch 511 and supplied to the battery 4. That is, charging current is supplied from the inverter 50 to the battery 4 by the motor generator 1.

  Smoothing capacitor 52 is provided in parallel with the current converter, and smoothes the current by repeating charge and discharge during operation of motor generator 1. A switch circuit 42 is provided between the smoothing capacitor 52 and the battery 4.

  The switch circuit 42 is a relay that brings the battery 4 and the inverter 50 into a connected state (ON) or a cut-off state (OFF). The switch circuit 42 is turned on and off by the controller 114. For example, the switch circuit 42 is set to ON when charging or discharging the battery 4, and is set to OFF when stopping charging or discharging of the battery 4.

  The battery 4 is a secondary battery configured by connecting a large number of chargeable / dischargeable battery cells in series. In the present embodiment, the battery 4 is a lithium battery having a rated capacity of 10 Ah (ampere hour). For example, the battery 4 outputs a DC voltage of 300 V by a battery cell group of 3.8 V (volt). The battery 4 is used as a power source for the motor generator 1.

  The battery management unit 41 manages the state of charging or discharging of the battery 4. The battery management unit 41 detects a charge / discharge state such as the temperature, voltage, current, and remaining battery capacity (SOC: State Of Charge) of the battery 4. For example, the battery management unit 41 acquires the battery temperature from a temperature sensor provided in the battery 4.

  The battery management unit 41 supplies a battery status signal indicating the battery temperature, voltage, current, remaining capacity, and the like to the controller 114. Further, when the remaining capacity of the battery 4 falls below the charging threshold, the battery management unit 41 supplies a charge request signal for requesting charging of the battery 4 to the controller 114.

  The controller 114 is a charge control device that controls the excavator 100. The controller 114 controls charging and discharging of the battery 4 based on a battery status signal, a charge request signal, and the like from the battery management unit 41.

  For example, when the ignition key 116 is turned on by the operation of the crew member and the main control valve 110 is set to the holding position c, the controller 114 charges the battery 4 when receiving a charge request signal from the battery management unit 41. Start-up charging operation is performed. Specifically, the controller 114 controls the pilot solenoid valve 23 to set the return control valve 22 to the communication position d, and controls the pilot solenoid valve 33 to set the sub control valve 32 to the shut-off position g. The circuit 42 is turned on.

  Alternatively, when the boom cylinder 104 is contracted by a crew member's lever operation, that is, when the main control valve 110 is set to the contracted position a, the controller 114 receives the charge request signal from the battery management unit 41 and receives the battery 4. Regenerative operation is performed. Specifically, the controller 114 controls the pilot solenoid valve 23 to set the return control valve 22 to the communication position d, and controls the pilot solenoid valve 33 to set the sub control valve 32 to the cutoff position g.

  Alternatively, when the boom cylinder 104 is extended by a crew member lever operation, that is, when the main control valve 110 is set to the extended position b, the controller 114 discharges the battery 4 to the motor generator 1 based on the battery state signal. And perform the assist operation.

  Specifically, when the battery state signal is higher than the charging threshold, the controller 114 turns on the switch circuit 42 to control the pilot solenoid valve 23 to set the return control valve 22 to the cutoff position e and The sub-control valve 32 is set to the communication position f by controlling the valve 33. Thereby, the motor generator 1 is driven by the power of the battery 4 to assist the main pump 8.

  On the other hand, when the battery state signal is below the charging threshold, the controller 114 controls the pilot solenoid valve 23 to set the return control valve 22 to the cutoff position e and controls the pilot solenoid valve 33 to turn the sub control valve 32 on. The battery 4 is stopped from being discharged and set at the cutoff position g.

  Next, the operation of the fluid pressure control device 120 according to the present embodiment will be described with reference to FIGS. 2 and 3.

  First, regeneration by the assist regeneration mechanism 10 performed as necessary when the load is lowered will be described.

  When a lever operation for contracting the boom cylinder 104 is performed by the crew of the hydraulic excavator, the main control valve 110 is switched to the contracted position a, and hydraulic oil is supplied to the rod side pressure chamber 104a and from the bottom side pressure chamber 104b. Hydraulic oil is discharged.

  At this time, when the return control valve 22 is switched to the communication position d as necessary, for example, when the battery charge amount of the battery 4 is relatively low, a part of the hydraulic oil discharged from the bottom side pressure chamber 104b is obtained. It is supplied to the regenerative motor 2 via the return passage 21. At the same time, the inclination angle of the swash plate is controlled so that the discharge amount from the assist pump 3 is minimized.

  Thereby, since the rotating shaft of the motor generator 1 rotates in synchronization with the rotating shaft of the regenerative motor 2, the motor generator 1 can generate electric power, and the battery 4 can be charged. That is, the hydraulic energy of the working fluid discharged from the boom cylinder 104 can be converted into electric energy.

  On the other hand, for example, when the battery charge amount of the battery 4 is relatively high, when the return control valve 22 is switched to the shut-off position e as necessary, all the hydraulic oil discharged from the bottom side pressure chamber 104b is second. It is discharged to the tank T through the passage 113, and regeneration is stopped.

  Next, assist by the assist regeneration mechanism 10 that is performed as necessary when the load increases will be described.

  When a lever operation for extending the boom cylinder 104 is performed by a crew member of the hydraulic excavator, the main control valve 110 is switched to the extended position b, the working oil is supplied to the bottom side pressure chamber 104b, and the rod side pressure chamber 104a The hydraulic oil is discharged to the tank T through the first passage 112.

  Here, the engine is operated at a predetermined rotational speed and load with good operating efficiency. Therefore, when it is desired to quickly extend the boom cylinder 104, the flow rate of hydraulic oil supplied to the bottom pressure chamber 104b may be insufficient with only the discharge amount by the driving force of the engine. In such a case, the assist regeneration mechanism 10 assists.

  Specifically, the battery generator 4 drives the motor generator 1 as an electric motor to drive the assist pump 3. Thereby, hydraulic fluid is discharged from the assist pump 3. As a result, the hydraulic oil discharged from the assist pump 3 can be joined to the main passage 111 via the sub passage 31 and an auxiliary force can be applied when the boom cylinder 104 is extended.

  Next, the case where the battery 4 is charged by the assist regeneration mechanism 10 will be described.

  When the controller 114 receives the charge request signal from the battery management unit 41, the controller 114 continuously charges the battery 4 at a charge rate determined by the battery capacity of the battery 4 or the like when the operation of the actuator is stopped. .

  For example, in the start-up charging operation, when the controller 114 receives a charge request signal from the battery management unit 41 when the main control valve 110 is set to the holding position c, the controller 114 switches the return control valve 22 to the communication position d, The circuit 42 is set to ON. Then, the controller 114 controls the inclination angle controller 24 to adjust the electromotive force of the motor generator 1 due to the rotation of the regenerative motor 2 so that the battery 4 has a charging current of 1.5 C rate, for example.

  In general, the battery 4 has a large internal resistance in a state where the battery temperature is lower than the freezing point temperature of 0 ° C., and is likely to deteriorate as compared with a normal temperature state higher than 0 ° C. Therefore, under a low temperature where the battery temperature is lower than the freezing point temperature, the upper limit (maximum value) of the charge rate that can avoid the deterioration of the battery 4 is lower than the normal charge rate (1.5 C rate) by 0.3 C rate. Become. For this reason, the battery is continuously charged (continuous charging) at a constant current of 0.3 C or less at low temperatures.

  As described above, in order to avoid the deterioration of the battery 4, it is necessary to set the charging rate at a low temperature lower than the normal charging rate. It was.

  Therefore, in the present invention, the secondary battery is intermittently charged at low temperatures (intermittent charging), whereby the battery is charged at a charge rate higher than the upper limit value of the charge rate at which continuous charging is possible at low temperatures.

  FIG. 4 is a functional block diagram showing the configuration of the controller 114 according to the embodiment of the present invention.

  The controller 114 includes a charge state determination unit 114a, a continuous charge control unit 114b, an intermittent charge control unit 114c, and a charge command unit 114d.

  The charging state determination unit 114 a determines the state of the battery 4 based on the battery state signal from the battery management unit 41. The charge state determination unit 114a determines whether or not the battery temperature indicated by the battery state signal is lower than the deterioration threshold. The deterioration threshold is a temperature threshold for preventing deterioration due to continuous charging of the battery 4, and is preferably set to the same value as the lower limit value of the operating temperature range of the battery 4. The deterioration threshold is set to 0 ° C., for example. The deterioration threshold value is stored in advance in, for example, the charging state determination unit 114a.

  When the charge state determination unit 114a receives the charge request signal from the battery management unit 41 and the battery temperature is lower than the deterioration threshold value, the charge state determination unit 114a intermittently controls the low temperature state information indicating that the battery 4 is in the low temperature state. 114c. On the other hand, when the battery temperature is equal to or higher than the deterioration threshold, the charging state determination unit 114a supplies normal state information indicating that the battery 4 is in a normal state to the continuous charging control unit 114b.

  When receiving the normal state information from the charge state determination unit 114a, the continuous charge control unit 114b continuously charges the battery 4 at a normal charge rate (for example, 1.5C rate) determined by the battery capacity of the battery 4.

  Specifically, the continuous charge control unit 114b supplies the charge command unit 114d with a current value of a charging current (hereinafter referred to as “normal charging current value”) when continuously charging at a 1.5 C rate.

  When the intermittent charge control unit 114c receives the low temperature state information from the charge state determination unit 114a, the intermittent charge control unit 114c intermittently charges the battery 4 so that the average value of the charge rate is larger than the maximum value of the charge rate that can be continuously charged at low temperature. To charge. The charge rate at which the battery 4 can be continuously charged at a low temperature is a charge rate at which the battery 4 can be prevented from deteriorating even if the battery 4 is continuously charged at a temperature lower than the deterioration threshold. The charge rate that can be continuously charged at a low temperature is a constant charge rate of 0.3 C or less.

  In the present embodiment, the intermittent charge control unit 114c intermittently charges the battery 4 with an average value of a 0.9C rate that is higher than the maximum value of the charge rate that can be continuously charged at a low temperature. Specifically, the intermittent charge control unit 114c includes a maximum current value (hereinafter, referred to as “low temperature charge current value”) higher than a constant current value by normal charging, and a charging current among predetermined intermittent periods. Is supplied to the charge command unit 114d.

  The current value of the low temperature charge is set higher than the current value of the normal charge in order to make the average charge rate in the low temperature charge close to a constant charge rate (1.5 C rate) in the normal charge. For example, the current value of the low-temperature charging is set to the current value of the charging current supplied to the battery 4 when continuously charging at the 3.2 C rate. That is, when the temperature of the secondary battery is lower than the deterioration threshold, the charging rate in the current supply period in which charging is performed in the intermittent cycle is greater than the charging rate at which the secondary battery is charged by the continuous charging control unit 114b. Charge the secondary battery.

  In addition, the stop period in which charging is stopped in the intermittent period is set longer than the current supply period in order to prevent deterioration due to charging of the battery 4. For example, the intermittent period is set to 7 seconds, the current supply period is set to 2 seconds, and the stop period is set to 5 seconds.

  Moreover, in order to reduce free discharge due to the internal resistance of the battery 4 during the stop period, a negative current on the discharge side corresponding to the internal resistance may be supplied to the battery 4. Thereby, in the battery 4 at a low temperature, it is possible to suppress deterioration due to free discharge accompanying an increase in internal resistance. As described above, when a negative current is supplied from the battery 4 during the stop period, the intermittent charge control unit 114c supplies the current value of the stop period to the charge command unit 114d together with the low-temperature charge current value and the intermittent information.

  The charge command unit 114d includes the pilot solenoid valve 23, the tilt angle controller 24, the pilot solenoid valve 33, the tilt angle controller 34, the switch circuit 42, the pilot solenoid valve in the start-up charging operation or the regenerative operation. 115 to charge the battery 4.

  For example, in the start-up charging operation, when the charge command unit 114d receives a normal charge current value from the continuous charge control unit 114b or a low-temperature charge current value from the intermittent charge control unit 114c, the operation of the actuator stops at the start-up. That is, it is confirmed that the main control valve 110 is in the holding position c.

  When the main control valve 110 is in the holding position c, the charge command unit 114d sets the switch circuit 42 to ON when receiving the low temperature charge current value and the intermittent information from the intermittent charge control unit 114c, and sets the switch circuit 42 to ON. The tilt angle controller 24 is controlled based on the value and the intermittent information. Specifically, the charging command unit 114d sets an inclination angle (charging inclination angle) corresponding to the current value of the low-temperature charging in the current supply period with respect to the inclination angle controller 24 at the intermittent period indicated by the intermittent information. In the stop period, an inclination angle (stop inclination angle) corresponding to a zero current value is set. Thereby, the battery 4 is intermittently charged at a charging rate (for example, 0.9 C rate) whose average value is higher than a constant charging rate (for example, 0.3 C rate) when continuously charging at a low temperature.

  In addition, when the charging command unit 114d receives the normal charging current value from the continuous charging control unit 114b, the charging command unit 114d turns on the switch circuit 42 and sets the inclination angle controller 24 to the inclination angle (normal inclination angle) corresponding to the normal charging current value. ). Then, the charging command unit 114d maintains the normal inclination angle setting until the battery 4 is fully charged. Thereby, the battery 4 is continuously charged at a normal charging rate (for example, 1.5 C rate).

  In this manner, the controller 114 continuously charges the battery 4 by the continuous charge control unit 114b at a normal temperature higher than 0 ° C., and intermittently charges the battery 4 by the intermittent charge control unit 114c at a low temperature lower than 0 ° C. Recharge. As a result, at a low temperature, it becomes possible to intermittently supply the charging current to the battery 4 at a higher charging rate than when the battery 4 is continuously charged, and the time required for charging the battery 4 can be shortened.

  FIG. 5 is a flowchart illustrating an example of a charging control method performed by the controller 114. In FIG. 5, the charging state determination unit 114 a acquires the battery temperature and the remaining battery capacity indicated by the battery state signal from the battery management unit 41.

  First, in step S910, the charge state determination unit 114a determines whether or not a charge request signal has been received from the battery management unit 41.

  In step S920, when the charge state determination unit 114a receives the charge request signal from the battery management unit 41, the charge state determination unit 114a determines whether the battery temperature is equal to or higher than the deterioration threshold value in order to determine the charge state of the battery 4. When the battery temperature is equal to or higher than the deterioration threshold, the charging state determination unit 114a supplies the normal state information to the continuous charging control unit 114b.

  In step S930, when the charge command unit 114d receives the normal state information from the charge state determination unit 114a, the charge command unit 114d controls the tilt angle controller 24 so that the battery 4 is continuously charged at the normal charge rate. In the present embodiment, the continuous charge control unit 114b sets the inclination angle controller 24 to the normal inclination angle corresponding to the current value of the 1.5C rate charging current, and continues the setting until the battery 4 reaches full charge. To do.

  On the other hand, when the battery temperature is lower than the deterioration threshold value in step S920, the low temperature state information is output to the intermittent charge control unit 114c by the charge state determination unit 114a. When the intermittent charge control unit 114c receives the low temperature state information from the charge state determination unit 114a, the intermittent charge control unit 114c intermittently charges the battery 4 at a 0.9C rate higher than a charge rate (less than 0.3C rate) when continuously charging at a low temperature. To charge.

  In the present embodiment, the intermittent charge control unit 114c calculates the current value of the charging current when continuously charging at the 3.2C rate, the current supply period of 2 seconds and the stop period of 5 seconds in the intermittent period of 7 seconds. The intermittent information shown is supplied to the charge command unit 114d.

  In step S951, the charging command unit 114d receives the current value of the charging current at the 3.2C rate and the intermittent information from the intermittent charging control unit 114c, and sets the inclination angle controller to the charging inclination angle corresponding to the current value of the charging current. 24 is adjusted.

  In step S952, the charging command unit 114d determines whether or not 2 seconds of the current supply period have elapsed since the inclination angle controller 24 was adjusted to the charging inclination angle in the intermittent period of 7 seconds.

  In step S953, the charging command unit 114d changes the inclination angle controller 24 to the stop inclination angle after 2 seconds have elapsed after adjusting the inclination angle controller 24 to the charging inclination angle, and sets the charging current to zero.

  In step S954, the charging command unit 114d determines whether or not 5 seconds of the stop period has elapsed since the inclination angle controller 24 was changed to the stop inclination angle.

  In step S940, the charging command unit 114d confirms the remaining capacity of the battery 4 after 5 seconds from the change of the tilt angle controller 24 to the stop tilt angle, and determines whether or not the battery 4 has reached full charge.

  If the charging of the battery 4 has not been completed, the charging command unit 114d returns to step S910, and until the battery temperature becomes equal to or higher than the deterioration threshold or until charging is completed, A charging current of 3.2 C rate is supplied to the battery 4 for 2 seconds. On the other hand, when the charging of the battery 4 is completed, a series of processing steps for the charge control method at a low temperature is completed.

  FIG. 6 is a diagram illustrating a waveform of the charging current supplied to the battery 4 at a low temperature. FIG. 6A is a diagram illustrating a waveform of a charging current to the battery 4 by the intermittent charging control unit 114c. FIG. 6B is a diagram illustrating a waveform of a charging current to the battery 4 by continuous charging at a low temperature.

  As shown in FIG. 6A, the charging current to the battery 4 is adjusted to a current value of 3.2 C rate for 2 seconds in the current supply period in the intermittent period 7 seconds by the intermittent charge control unit 114c. Is adjusted to zero for 5 seconds. As a result, the battery 4 is charged at a 0.9 C rate {(5 s × 0 C + 2 s × 3.2 C) ÷ 7 s}.

  As shown in FIG. 6B, generally, in order to avoid deterioration due to continuous charging of the battery 4 at a low temperature, the battery 4 is continuously charged at a charge rate of 0.3 C rate.

  As described above, in this embodiment, the battery 4 is intermittently supplied with a charging current, so that the battery can be charged at a charging rate (0.9 C rate) larger than a charging rate (0.3 C rate) that can be continuously charged at a low temperature. 4 can be charged. Thereby, the charge time of the battery 4 can be shortened.

  FIG. 7 is a diagram illustrating deterioration characteristics of the battery 4 due to intermittent charging and continuous charging at low temperatures.

  In FIG. 7, the deterioration characteristics when the battery 4 is intermittently charged by the intermittent charge control unit 114c as shown in FIG. 6A are indicated by broken lines, and the battery 4 is charged at the same charge rate as the intermittent charge control unit 114c. The deterioration characteristics when the battery is continuously charged are indicated by a solid line. In FIG. 7, the horizontal axis indicates the number of charge / discharge cycles of the battery 4, and the vertical axis indicates the battery capacity (full charge capacity) of the battery 4.

  As shown in FIG. 7, when the battery 4 is continuously charged at a low temperature of 0 ° C. or lower, the battery capacity gradually decreases each time charging / discharging is repeated. On the other hand, when intermittent charging is performed by the intermittent charging control unit 114c, it is understood that the battery 4 is not deteriorated even if charging / discharging is repeated.

  In this way, by intermittently charging the battery 4 at a low temperature, it is possible to increase the charging rate of the battery 4 compared to the continuous charging at a low temperature while suppressing deterioration of the battery 4.

  According to the above embodiment, there exist the effects shown below.

  When it is determined by the charging state determination unit 114a that the battery temperature is lower than the deterioration threshold, the controller 114 has a charging rate higher than a charging rate at which deterioration due to continuous charging can be avoided at a temperature lower than the deterioration threshold. The battery 4 is intermittently charged.

  Thus, by intermittently charging the battery 4 at a low temperature, the battery 4 can be fully charged at a charge rate higher than a charge rate (0.3C rate or less) that can be continuously charged at a low temperature. Become. Therefore, the charging time required for charging the battery 4 at a low temperature can be shortened.

  Further, in the present embodiment, the intermittent charge control unit 114c stops the charging of the battery 4 more than the current supply period in which the charging current is supplied to the battery 4 in the intermittent period for intermittently charging the battery 4. Set a longer period.

  For example, by setting the current supply period to 2 seconds and setting the stop period to 5 seconds in the intermittent period as shown in FIG. 6A, the battery 4 is deteriorated as shown by the solid line in FIG. Can be suppressed, and the battery 4 can be charged early at a low temperature.

  Further, in the present embodiment, the intermittent charge control unit 114c intermittently charges the battery 4 with a current larger than the charge current supplied to the battery 4 by the continuous charge control unit 114b.

  As a result, the charge rate of the battery 4 at a low temperature can be brought close to the charge rate by continuous charging at a normal temperature equal to or higher than the deterioration threshold. For this reason, even at a low temperature, the charging time until the battery 4 is fully charged can be close to the charging time by continuous charging at the normal temperature.

  Moreover, the hybrid construction machine is generally provided with a heater for heating the battery 4. According to the present invention, since the battery 4 can be charged in a short time while suppressing deterioration of the battery 4 even at low temperatures, it is not always necessary to warm the battery 4 with a heater when charging at low temperatures. Alternatively, the warm-up time by the heater can be shortened. Therefore, the power consumption of the heater can be suppressed and the battery 4 can be charged efficiently.

  In this embodiment, the hybrid construction machine is connected to the main pump 108 that drives the boom cylinder 4, the assist pump 3 that assists the driving of the boom cylinder 4 by the main pump 8, and the fluid pressure is connected to the assist pump 3. Regenerative motor 2 that receives and rotates, motor generator 1 that converts the rotational force of regenerative motor 2 into electric power, and inverter 50 that charges battery 4 with the electric power converted by motor generator 1 are provided.

  When the battery temperature is equal to or higher than the deterioration threshold, the continuous charge control unit 114b controls the rotation of the regenerative motor 2 so as to continuously charge the battery 4 via the inverter 50, and charges the battery 4. Adjust the current. In addition, the intermittent charge control unit 114c controls the rotation of the regenerative motor 2 with the swash plate angle controller 24 when the battery temperature is lower than the deterioration threshold, and the charge current is controlled by the continuous charge control unit 114b. A large charging current is intermittently supplied from the inverter 50 to the battery 4.

  Thus, even when a hybrid construction machine such as a hydraulic excavator is started at a low temperature, even when the regenerative motor 2 is driven by the main pump 108 and the battery 4 is charged from the motor generator 1, the intermittent charge control unit 114c. Can be charged early.

  Moreover, in this embodiment, the intermittent charge control part 114c controls rotation of the regenerative motor 2 intermittently by changing the swash plate angle of the regenerative motor 2 intermittently. Thereby, the charging current can be intermittently supplied to the battery 4.

  In the above-described embodiment, when the charging current is intermittently supplied to the battery 4, the swash plate angle of the regenerative motor 2 is intermittently changed. However, other methods may be used. For example, a clutch may be provided between the motor generator 1 and the regenerative motor 2, and the clutch may be disengaged when it is desired to cut off the charging current of the battery 4. On the other hand, when it is desired to supply the charging current of the battery 4, a clutch may be connected.

  The present invention may be applied not only to a hybrid construction machine but also to an idling stop mixer vehicle. In the idling stop mixer vehicle, a hydraulic motor for rotating the mixer drum is provided instead of the boom cylinder 104. When performing the regenerative operation, the hydraulic motor is driven by the hydraulic pressure of the main pump 108 to rotate the mixer drum, and the main control valve 110 and the return control valve 22 are driven so that the excess hydraulic pressure drives the regenerative motor 2. Provide an alternative valve. The regenerative motor 2 and the assist pump 3 may be combined to form a single hydraulic pump motor.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

100 Hydraulic excavator (hybrid construction machine)
114 controller (charge control device)
114a Charge state determination unit 114b Continuous charge control unit 114c Intermittent charge control unit 1 Motor generator (rotary electric machine)
2 Regenerative motor 3 Assist pump (sub fluid pressure pump)
50 Inverter 104 Boom cylinder (actuator)
108 Main pump (Main fluid pressure pump)

Claims (5)

A determination unit that determines whether the temperature of the secondary battery is lower than a deterioration threshold for preventing deterioration due to charging of the secondary battery;
When the determination unit determines that the temperature of the secondary battery is lower than the deterioration threshold, the charge rate is higher than the upper limit of the charge rate that can avoid deterioration due to continuous charging at a temperature lower than the deterioration threshold. An intermittent charge control unit that intermittently charges the secondary battery so as to increase the average value;
A charge control device comprising: The intermittent charge control unit sets a period for stopping charging longer than a period for supplying a charging current to the secondary battery in the intermittent period for intermittently charging the secondary battery.
The charge control device according to claim 1. When the determination unit determines that the temperature of the secondary battery is equal to or higher than the deterioration threshold, the battery further includes a continuous charge control unit that continuously charges the secondary battery,
When the determination unit determines that the temperature of the secondary battery is lower than a deterioration threshold, the intermittent charge control unit charges the secondary battery with a charge rate during a current supply period by the continuous charge control unit. Intermittently charging the secondary battery so that the charging rate is greater than
The charge control device according to claim 1 or 2. The charge control device according to any one of claims 1 to 3,
A main fluid pressure pump that drives the actuator;
A sub-fluid pressure pump that assists in driving the actuator by the main fluid pressure pump;
A regenerative motor connected to the sub-fluid pressure pump and rotating by receiving fluid pressure;
A rotating electrical machine that converts the rotational force of the regenerative motor into electric power;
An inverter that charges the secondary battery with the electric power converted by the rotating electrical machine,
When the determination unit determines that the temperature of the secondary battery is lower than a deterioration threshold, the intermittent charge control unit is configured to intermittently charge the secondary battery via the inverter. A hybrid construction machine that controls the rotation of the motor intermittently. The regenerative motor is a swash plate type motor that can change the output by adjusting the inclination angle of the swash plate,
The intermittent charge control unit controls rotation of the regenerative motor by changing a swash plate angle of the regenerative motor;
The hybrid construction machine according to claim 4.

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