JP2013163946A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine capable of discharging a power conversion device when a casing is opened by a simple configuration.SOLUTION: An inverter 18, a chopper 20, and a power conversion device 17 provided with a smoothing capacitor 21 and a discharge resistor 22 are provided between a battery 16 and an electric motor 15. A relay 23 is provided between the power conversion device 17 and the battery 16. A casing 27 accommodates the power conversion device 17 and is covered by a cover body 31. The cover body 31 is attached to the casing 27 by bolts 33 and detachably fixed thereto. A connector 36 is attached to a fixed bracket 34 provided on the cover body 31, covering the bolts. When the connector 36 is removed from the fixed bracket 34, the relay 23 enters a cutoff state.

Description

  The present invention relates to a construction machine including a power conversion device that performs power conversion between an electric motor and a power storage device.

  Electric or hybrid hydraulic excavators are known as construction machines. Such a construction machine includes, for example, an electric motor for driving a hydraulic pump, turning operation, and traveling operation, and an electric power conversion device such as an inverter or chopper that performs electric power conversion between the electric motor and the power storage device. ing. Moreover, the structure which accommodated the power converter device in the casing is known (for example, refer patent document 1).

JP 2006-136097 A

  By the way, power converters, such as an inverter, are provided with the smoothing capacitor for smoothing DC power, for example. Since a high voltage of about several hundred volts, for example, is applied to the smoothing capacitor, the smoothing capacitor is charged by the high voltage. For this reason, when the casing is opened and the power converter is inspected and maintained, it is necessary to discharge the smoothing capacitor.

  In consideration of this point, Patent Document 1 discloses a configuration in which a hook portion that locks the casing and a safety plug that opens the hook portion are provided, and power supply from the battery is stopped by the safety plug. However, in the configuration of Patent Document 1, when the hook part is unlocked by the safety plug, the power supply from the battery is stopped, but the casing can be opened before the discharge of the smoothing capacitor of the power converter is completed. There's a problem.

  In addition, it is conceivable to provide a separate switch for discharging the smoothing capacitor. However, since construction machinery is subject to a greater vibration than passenger cars, special switches with excellent vibration resistance are required, which increases manufacturing costs. There is also the problem of doing.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a construction machine capable of discharging a power converter when a casing is opened with a simple configuration.

  In order to solve the above-described problems, the invention of claim 1 is directed to an electric motor as a drive source, a power storage device that can be electrically connected to the electric motor, and power between the electric motor and the power storage device. In a construction machine including a power conversion device that performs conversion and a switch that connects or disconnects the power conversion device and the power storage device, a casing that houses the power conversion device and an opening of the casing are provided. A lid for covering, a bolt for attaching and detaching the lid to the casing, a fixing bracket provided on the lid or the casing, and a fixing bracket for attaching to and removing from the fixing bracket; A connector that covers the bolt in an attached state, and when the connector is attached to the fixing bracket, the switch is in a connectable state. When removed the connector from the fixed bracket is characterized in that the switch becomes off.

  According to a second aspect of the present invention, the power conversion device includes a smoothing capacitor that smoothes DC power and a discharge resistor connected in parallel to the smoothing capacitor, and a screwing depth dimension of the bolt is the smoothing capacitor. Is set based on the time required to complete the discharge.

  According to a third aspect of the present invention, the switch includes an exciting coil that is connected to the power storage device via a power supply line and is excited by power feeding from the power storage device, and a contact that is switched between a connected state and a cut-off state by the exciting coil. The connector is provided with a connection line for connecting the power supply line, and when the connector is attached to the fixed bracket, the power supply line is connected by the connection line, and the connector is connected to the fixed bracket. When it is removed from the power supply line, the feed line is cut off.

  According to the first aspect of the present invention, since the bolt for fixing the lid of the casing is covered by the connector, when removing the bolt, it is necessary to remove the connector from the fixing bracket. At this time, when the connector is removed from the fixed bracket, the switch provided between the power conversion device and the power storage device is cut off, so that the discharge of the power conversion device can be started at this point. As a result, the discharge time of the power conversion device can be ensured by the time required for removing the bolts. Therefore, when removing the lid and opening the casing, the power conversion device should be in a sufficiently low voltage state. Can do.

  According to the second aspect of the invention, since the power conversion device includes the smoothing capacitor and the discharge resistor, when the connector is detached from the fixed bracket, the electric charge accumulated in the smoothing capacitor can be discharged using the discharge resistor. In addition, since the threading depth dimension of the bolt is set based on the time required to complete the discharge of the smoothing capacitor, for example, even when the time constant due to the smoothing capacitor and the discharge resistance increases and the discharge time becomes long, The threading depth of the bolt can be increased. Thereby, it is possible to ensure a sufficient discharge time of the smoothing capacitor.

  According to the invention of claim 3, since the connector is provided with the connection line for connecting the power supply line, when the connector is removed from the fixed bracket, the power supply line is cut off and the power supply to the exciting coil can be stopped. As a result, the relay contacts are switched to the cut-off state, and the power converter can be started to discharge.

1 is a front view showing a hydraulic excavator according to an embodiment of the present invention. It is a circuit diagram which shows the structure of the electric system applied to the hydraulic shovel in FIG. It is a perspective view which shows the casing which accommodates the power converter device in FIG. It is sectional drawing which looked at the casing etc. from the arrow IV-IV direction in FIG. It is sectional drawing which looked at the connector, the fixing bracket, the volt | bolt, etc. from the arrow VV direction in FIG.

  Hereinafter, an electric hydraulic excavator will be described as an example of a construction machine according to an embodiment of the present invention, and will be described in detail with reference to the accompanying drawings.

  In the figure, reference numeral 1 denotes a lower traveling body of a hydraulic excavator, and an upper revolving body 2 is mounted on the lower traveling body 1 so as to be able to swivel. Further, the upper swing body 2 is provided with a cab 3 that defines an operator cab, and a building cover 4 that houses a hydraulic pump 12, an electric motor 15, and the like to be described later is provided behind the cab 3. Here, the lower traveling body 1 is provided with a traveling motor, and the upper revolving body 2 is provided with a turning motor (both not shown). The lower traveling body 1 performs traveling operations such as forward and backward movement by a traveling motor, and the upper revolving body 2 is swung by a swing motor.

  Reference numeral 5 denotes a working device (front) attached to the front portion of the upper swing body 2 so as to be able to move up and down. The working device 5 includes a boom 6, an arm 7, a bucket 8, and the like. A hydraulic cylinder such as a boom cylinder 9, an arm cylinder 10, and a bucket cylinder 11 is attached to the cylinder. And these cylinders 9-11 comprise the actuator driven with the hydraulic oil supplied from the hydraulic pump 12 with hydraulic motors, such as a travel motor and a turning motor.

  Reference numeral 12 denotes a hydraulic pump as a hydraulic source. The hydraulic pump 12 is disposed inside the building cover 4 of the upper swing body 2 together with an electric motor 15 and the like which will be described later. Then, as shown in FIG. 2, the hydraulic pump 12 is rotationally driven by the electric motor 15 to generate pressure oil. The hydraulic pump 12 is connected to the cylinders 9 to 11 and the like via a control valve device (C / V) 13 composed of a plurality of directional control valves, and sucks the hydraulic oil in the oil tank 14 to provide high pressure oil. And the pressure oil is supplied toward each of the cylinders 9 to 11 and the like.

  At this time, when the operator operates an operation lever (not shown) or the like in the cab 3, the control valve device 13 is switched. Thereby, for example, supply and discharge of pressure oil to each cylinder 9 to 11 are switched, and the expansion and contraction operation of each cylinder 9 to 11 is controlled using the control valve device 13.

  Reference numeral 15 denotes an electric motor as a drive source. Specifically, as shown in FIG. 2, the output shaft of the electric motor 15 is connected to the hydraulic pump 12 and functions as a drive source of the hydraulic pump 12. Further, the electric motor 15 is provided in the upper swing body 2 in the vicinity of the hydraulic pump 12, and is constituted by, for example, a three-phase induction motor, a three-phase synchronous motor, or the like. The electric motor 15 is rotationally driven by three-phase AC power supplied from an inverter 18 described later, and drives the hydraulic pump 12 through its output shaft.

  Reference numeral 16 denotes a battery as a power storage device that can be electrically connected to the electric motor 15. The battery 16 is provided on the rear side of the upper swing body 2 and is constituted by a secondary battery such as a lithium ion battery. Further, since the battery 16 itself is a heavy object, the battery 16 also functions as a counterweight for the heavy load applied to the work device 5. The battery 16 can be electrically connected to the electric motor 15 via an inverter 18 and a chopper 20 of the power converter 17 described later.

  Reference numeral 17 denotes a power converter that performs power conversion between the electric motor 15 and the battery 16. The power converter 17 is disposed in the building cover 4. Specifically, the power conversion device 17 performs power conversion between AC power and DC power and power conversion that reduces or boosts a DC voltage. And the power converter device 17 is comprised by the inverter 18, the chopper 20, the smoothing capacitor 21, etc. which are mentioned later.

  Reference numeral 18 denotes an inverter electrically connected to the electric motor 15. The inverter 18 is configured by using a plurality of (for example, six) switching elements S composed of, for example, a transistor, a thyristor, an insulated gate bipolar transistor (IGBT), or the like. Here, the inverter 18 generates three-phase AC power from DC power, for example, by controlling on / off of the switching element S using the control unit 18A. The inverter 18 supplies three-phase AC power to the electric motor 15 and drives the electric motor 15. The inverter 18 is electrically connected to the chopper 20 via a pair of DC buses 19A and 19B on the plus side and the minus side.

  Reference numeral 20 denotes a chopper electrically connected between the battery 16 and the inverter 18. The chopper 20 is electrically connected to the output side of the battery 16 and the input side of the inverter 18. The chopper 20 includes a plurality of (for example, two) switch elements S and a reactor L made of, for example, IGBT. In the chopper 20, the on / off state of the switch element S is controlled by the control unit 20 </ b> A. Thus, when driving the electric motor 15 using the battery 16, the chopper 20 functions as a booster circuit (boost chopper), boosts the DC voltage output from the battery 16, and supplies the boosted voltage to the inverter 18.

  The DC buses 19A and 19B are connected to an external power source (not shown) such as a commercial power source via a rectifier circuit or the like, for example. For this reason, when charging the battery 16 using an external power source, the chopper 20 functions as a step-down circuit (step-down chopper), and steps down the DC voltage between the DC buses 19A and 19B and supplies it to the battery 16.

  A smoothing capacitor 21 is located between the inverter 18 and the chopper 20 and connected between the DC buses 19A and 19B. The smoothing capacitor 21 smoothes the DC power supplied between the DC buses 19A and 19B. . Further, a discharge resistor 22 is connected in parallel to the smoothing capacitor 21. Here, the time constant of the smoothing capacitor 21 and the discharge resistor 22 is set to about several tens of seconds, for example. For this reason, when the electric motor 15 is driven by the power supply from the battery 16, the discharge by the discharge resistor 22 hardly occurs. On the other hand, for example, when the chopper 20 and the battery 16 are disconnected by the relay 23 and the power supply between the DC buses 19A and 19B is lost, the electric charge accumulated in the smoothing capacitor 21 is discharged through the discharge resistor 22.

  Reference numeral 23 denotes a battery relay as a switch for connecting or disconnecting the power converter 17 and the battery 16. The relay 23 is provided between the chopper 20 and the battery 16 and includes contacts 24A and 24B and an excitation coil MC. The excitation coil MC is connected to the battery 16 via the power supply line 25 and is excited by power supply from the battery 16. The contacts 24A and 24B correspond to the positive side terminal and the negative side terminal of the battery 16, respectively, and the connection state (ON) and the cutoff state (OFF) are switched by the exciting coil MC.

  Further, a drive circuit 26 made of a switching element such as a transistor is provided in the middle of the feed line 25, and the drive circuit 26 is connected in series to the exciting coil MC. The drive circuit 26 is switched on / off in response to, for example, an ignition key (not shown) being turned on / off. For this reason, when the ignition key is on, the exciting coil MC is in an excited state, and the contacts 24A and 24B are in a connected state. On the other hand, when the ignition key is off, the exciting coil MC is in a non-excited state, and the contacts 24A and 24B are in a cut-off state. In this way, the relay 23 connects or disconnects between the chopper 20 and the battery 16.

  Reference numeral 27 denotes a casing for housing the power converter 17. As shown in FIGS. 3 and 4, the casing 27 is formed, for example, in a box shape having an open top, and includes two receiving spaces 28 and 29 on the bottom side and the opening side. Here, for example, the inverter 18, the chopper 20, the smoothing capacitor 21, and the like are disposed in the accommodation space 28 on the bottom side, and the control units 18 </ b> A and 20 </ b> A are disposed in the accommodation space 29 on the opening side. . Further, the casing 27 is provided with a control connector 30 for connecting between the control units 18A and 20A and an external control circuit (not shown).

  Reference numeral 31 denotes a lid that covers the opening 27 </ b> A of the casing 27. The lid 31 is provided with a plurality of power connectors 32 for connection to the electric motor 15 and the battery 16. The outer edge portion of the lid body 31 is fixed to the casing 27 with screws by a plurality of bolts 33. That is, the bolt 33 attaches the lid body 31 to the casing 27 and fixes it so that it can be removed. For this reason, the lid body 31 can be removed from the casing 27 when all the bolts 33 are removed.

  Reference numeral 34 denotes a fixed bracket provided on the lid 31. As shown in FIGS. 3 to 5, the fixing bracket 34 is located on the outer edge side of the lid 31 and is attached to the upper portion of the lid 31 using, for example, an L-shaped stay 35. A pair of terminals 34 </ b> A and 34 </ b> B connected to the feeder line 25 are provided inside the fixed bracket 34.

  Reference numeral 36 denotes a connector that can be attached to and detached from the fixing bracket 34 and covers the bolt 33 in a state of being attached to the fixing bracket 34. Specifically, the connector 36 is attached to the fixed bracket 34 and covers, for example, one bolt 33 from above. For this reason, in the state where the connector 36 is attached to the fixed bracket 34, the bolt 33 cannot be removed and the lid 31 cannot be removed. In addition, a connection line 36 </ b> A made of, for example, a conductive metal is provided inside the connector 36. When the connector 36 is attached to the fixed bracket 34, the terminals 34A and 34B are electrically connected by the connection line 36A, and power can be supplied to the exciting coil MC. For this reason, when the connector 36 is attached to the fixed bracket 34, the relay 23 is in a connectable state.

  On the other hand, when the connector 36 is removed from the fixed bracket 34, the terminals 34A and 34B are electrically disconnected, and the power supply to the exciting coil MC is stopped. For this reason, when the connector 36 is removed from the fixed bracket 34, the relay 23 is cut off, and the electric charge of the smoothing capacitor 21 is discharged through the discharge resistor 22.

  The bolt 33 covered by the connector 36 has a screwing depth dimension D set based on the time required for the discharge of the smoothing capacitor 21 to be completed. That is, when the time constant of the smoothing capacitor 21 and the discharge resistor 22 is large, the screwing depth dimension D is long, and when the time constant is small, the screwing depth dimension D is short.

  In addition, the connector 36 includes a hook (not shown) for locking to the fixed bracket 34, and operation portions 37 for releasing the hook locking state are provided on both sides in the width direction of the connector 36. . In order to prevent the connector 36 from being lost, for example, the connector 36 and the fixed bracket 34 may be connected by a rope or the like.

  The hydraulic excavator according to the present embodiment has the above-described configuration, and the operation thereof will be described next.

  When the inverter 18 and the chopper 20 of the power converter 17 are operated with the relay 23 in the connected state, electric power is supplied from the battery 16 to the electric motor 15. Thereby, the electric motor 15 drives the hydraulic pump 12, and the hydraulic pump 12 generates pressure oil. As a result, by supplying this pressure oil to each of the cylinders 9 to 11 and the like, a traveling operation by the lower traveling body 1, a turning operation by the upper revolving body 2, an excavation work by the work device 5, and the like can be performed.

  Further, when the power converter 17 is inspected or maintained, the operator removes the connector 36 from the fixed portion racket 34. As a result, the feeding line 25 of the exciting coil MC is cut off, so that the exciting coil MC is in a non-excited state, and the contacts 24A and 24B of the relay 23 are cut off. Thereby, the electric charge accumulated in the smoothing capacitor 21 is discharged by the discharge resistor 22.

  Next, the operator removes all the bolts 33. At this time, since the discharge of the smoothing capacitor 21 proceeds while the bolt 33 is removed, the smoothing capacitor 21 is in a sufficiently low voltage state when all the bolts 33 are removed. As a result, the operator can remove the lid 31 from the casing 27 and inspect and maintain the power conversion device 17.

  Thus, according to the present embodiment, the connector 36 covers the bolt 33 that fixes the lid 31 of the casing 27, and therefore, when removing the bolt 33, it is necessary to remove the connector 36 from the fixing bracket 34. At this time, when the connector 36 is removed from the fixed bracket 34, the relay 23 provided between the power conversion device 17 and the battery 16 is in a cut-off state, so that the discharge of the power conversion device 17 is started at this point. Can do. As a result, the discharge time of the power conversion device 17 can be ensured by the time required to remove the bolts 33. Therefore, when the cover 31 is removed and the casing 27 is opened, the power conversion device 17 is sufficiently low in voltage. It can be in a state.

  Further, since the power conversion device 16 includes the smoothing capacitor 21 and the discharge resistor 22, when the connector 36 is detached from the fixed bracket 34, the electric charge accumulated in the smoothing capacitor 21 can be discharged using the discharge resistor 22. In addition, since the threading depth of the bolt 33 is set based on the time required to complete the discharge of the smoothing capacitor 21, for example, the time constant due to the smoothing capacitor 21 and the discharge resistor 22 becomes large and the discharge time is long. Even if it becomes, the screwing depth dimension D of the volt | bolt 33 can be lengthened. Thereby, the discharge time of the smoothing capacitor 21 can be sufficiently secured.

  Further, since the connector 36 is provided with a connection line 36A for connecting the power supply line 25, when the connector 36 is detached from the fixed bracket 34, the power supply line 25 is cut off and power supply to the exciting coil MC can be stopped. As a result, the contacts 24A and 24B of the relay 23 are switched to the cut-off state, and the electric power converter 17 can start discharging.

  In the above embodiment, the connector 36 covers one bolt 33, but may cover a plurality of bolts 33. A longer discharge time can be secured by increasing the number of bolts covered by the connector.

  In the embodiment, the fixing bracket 34 is provided on the lid 31. However, since the connector only needs to cover the bolt, the fixing bracket may be provided on the casing.

  Moreover, in the said embodiment, although the battery 16 was used for the said electrical storage apparatus, the other apparatus which stores electric power like a capacitor etc. may be sufficient.

  In the above embodiment, the electric hydraulic excavator that drives the hydraulic pump 12 by the electric motor 15 has been described as an example. However, the present invention is not limited to this, and may be applied to, for example, a hybrid construction machine including an electric motor used for power generation and driving in addition to an engine. The electric motor is not limited to driving a hydraulic pump, for example, You may use for a turning motor, a traveling motor, etc.

  In the above embodiment, a tracked hydraulic excavator has been described as an example of the construction machine. However, the present invention is not limited to this, and for example, other types such as a wheeled hydraulic excavator and a wheel loader can be used. It can be widely applied to electric and hybrid construction machines.

15 Electric motor 16 Battery (power storage device)
17 Power Converter 18 Inverter 20 Chopper 21 Smoothing Capacitor 22 Discharge Resistance 23 Relay (Switch)
24A, 24B Contact 25 Feed line 27 Casing 27A Opening 31 Lid 33 Bolt 34 Fixed bracket 36 Connector 36A Connection line S Switching element MC Excitation coil

Claims (3)

An electric motor as a drive source, a power storage device that can be electrically connected to the electric motor, a power conversion device that performs power conversion between the electric motor and the power storage device, the power conversion device, and the power storage device Construction machine with a switch for connecting or disconnecting between
A casing for housing the power conversion device, a lid for covering the opening of the casing, a bolt for attaching the lid to the casing and detachably fixing the lid, or the lid or the casing. A fixing bracket, and a connector that is attached to and can be removed from the fixing bracket and covers the bolt in a state of being attached to the fixing bracket;
The construction machine is characterized in that when the connector is attached to the fixed bracket, the switch is in a connectable state, and when the connector is removed from the fixed bracket, the switch is in a cut-off state. The power converter includes a smoothing capacitor that smoothes DC power, and a discharge resistor connected in parallel to the smoothing capacitor,
The construction machine according to claim 1, wherein a screwing depth dimension of the bolt is set based on a time required for completing discharge of the smoothing capacitor. The switch is configured by a relay including an excitation coil that is connected to the power storage device via a power supply line and is excited by power feeding from the power storage device, and a contact that is switched between a connection state and a cutoff state by the excitation coil.
The connector is provided with a connection line for connecting the feed line,
The power supply line is connected by the connection line when the connector is attached to the fixed bracket, and the power supply line is blocked when the connector is removed from the fixed bracket. Construction machinery.

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