Patent Description:
As the background art in regard to the technical field, there are techniques disclosed in Patent Document <NUM> and Patent Document <NUM>. Patent Document <NUM> discloses the technique on disconnection of a relay at the vehicle stop request in a motor/generator and a high voltage circuit of an electric vehicle. Patent Document <NUM> discloses the technique on disconnection of a relay at the system main relay disconnection request due to a hybrid system failure.

Recently, as measures of environment destruction prevention, the tightening of emission regulations of gases emitted due to combustion of fuel or low fuel consumption of a system with an internal combustion engine as a power source has been in progress by developed countries as leaders. As one of the measures, the approach of motorizing the power source mounted on the system has been made. The motorization of the power source can be achieved by using an electricity storage device storing power as the power source and driving an electric motor mechanically connected to a driven body with the power supplied from the electricity storage device. The electricity storage device is provided with a plurality of capacitors electrically connected in series, in parallel, or in series and in parallel. In many cases a secondary cell such as a lithium-ion cell, a lead cell or a nickel-hydrogen cell is used in the capacitor. Recently, among the secondary cells, adoption of the lithium-ion cell high in output of energy and in volumetric density in capacity has spread as the mainstream.

For continuing to safely use of the electricity storage device over a long period of time, the capacitor is required to be not used over the use range. That is, it is required to control charge/discharge of the capacitor in such a manner that a voltage, a charge/discharge current, a temperature, a charging state, a degradation state and the like of the capacitor are monitored to prevent the capacitor from leading to an abnormal state such as overcharge, over-discharge or an overtemperature. Therefore, the electricity storage device is provided with a controller configured to manage the aforementioned monitoring and control. In a case where the capacitor becomes in the abnormal state such as overcharge, over-discharge or an overtemperature, it is necessary to disconnect an electrical circuit between the electricity storage device and the electric motor and electrically disconnect the electricity storage device from the electric motor side. Therefore, a relay is provided in the electrical circuit between the electricity storage device and the electric motor, as described in Patent Document <NUM> for example. The relay can input or disconnect a contact point by controlling an operating current (an excitation current flowing in an excitation coil), as described in Patent Document <NUM>.

Patent Document <NUM> relates to a hybrid construction machine comprising an engine, a controller, a first power storage device, a second power storage device and an engine stop control section. The hybrid construction machine of Patent Document <NUM> further comprises an engine restart control section which restarts the engine by driving the assist power generation motor when a restarting device is operated after the engine is stopped.

Patent Document <NUM> relates to an electrical storage system. The electrical storage system of Patent Document <NUM> includes an electrical storage device, a relay, a controller and a current interruption circuit interrupting energization of the electrical storage device.

In the background art, however, the operating current of the relay is controlled by a single control system. Therefore, in a case where the control system controlling the operating current in the relay is in failure or erroneously operated, the relay is not normally operated and the electricity storage device is not disconnected electrically from the electric motor side, possibly leading the capacitor to the abnormal state such as overcharge, over-discharge or an overtemperature.

In view of the above-mentioned, one of the problems to be solved by the present invention is to improve certainty on the circuit disconnection by the relay.

One of the problems can be solved by means of a hydraulic excavator according to claim <NUM>, wherein a relay control section configured to control supply and stop of an operating current in a relay is provided in each of at least two controllers and the supply or stop of the operating current in the relay can be achieved by the relay control section in each of the controllers. In this case, it is preferable that the supply or the stop of the operating current in the relay by the relay control section in one of the controllers can be achieved without any relation to the supply or stop of the operating current in the relay by the relay control section in the other of the controllers. In addition, it is preferable that the supply or the stop of the operating current in the relay by the relay control section by the one of the controllers is achieved after a predetermined time has elapsed from a point when the supply or stop of the operating current in the relay is required, for example, a time until the current flowing between the electricity storage device and the electric motor becomes in a zero state by the disconnection of the relay or a time until the supply of the operating current in the relay by the relay control section in the other of the controllers is stopped has elapsed.

Here, according to one aspect of the present invention, a construction machine includes: an electric motor; a hydraulic pump driven by the electric motor; a hydraulic device driven by pressurized oil delivered from the hydraulic pump; an electricity storage device that supplies power to the electric motor; an inverter provided between the electricity storage device and the electric motor to convert the power; a main controller that controls the hydraulic pump and the hydraulic device; an electricity storage device controller that controls the electricity storage device; an equipment controller that controls the electric motor, the inverter and the electricity storage device controller; and a relay connecting or disconnecting an electrical circuit to which the inverter and the electricity storage device are connected, characterized in that: the equipment controller and the electricity storage device controller each include an excitation current control section that controls supply and stop of an excitation current in the relay.

According to another aspect of the present invention, an electric system includes: an electric motor driving a driven body; an electricity storage device that supplies power to the electric motor; an inverter provided between the electric motor and the electricity storage device to convert the power supplied from the electricity storage device and supply the converted power to the electric motor; a relay provided between the electricity storage device and the inverter to electrically connect or disconnect the electricity storage device and the inverter; an electricity storage device controller that manages a state of the electricity storage device; an upper controller that communicates with the electricity storage device controller, characterized in that: the electricity storage device controller and the upper controller each include a relay control section that controls supply and stop of an operating current in the relay.

Further, according to a further other aspect of the present invention, an electricity storage device controller in an electricity storage device that is connected electrically via a relay to an inverter and supplies power via the inverter to an electric motor driving a driven body, includes: an electricity storage device abnormal state notifying section configured to, when the electricity storage device becomes in an abnormal state of electrically disconnecting the electricity storage device and the inverter by the relay, notify an upper controller provided with a relay control section that controls supply and stop of an operating current in the relay of the abnormal state of the electricity storage device; and a relay control section configured to, when the electricity storage device becomes in the abnormal state of electrically disconnecting the electricity storage device and the inverter by the relay, stop the supply of the operating current in the relay with no relation to whether or not the supply of the operating current in the relay is stopped by the upper controller notifying the abnormal state of the electricity storage device.

According to the present invention, it is possible to improve certainty of the circuit disconnection by the relay.

That is, an explanation will be made of a construction machine as one aspect of the present invention, as an example, the equipment controller and the electricity storage device controller each include the excitation current control section (the relay control section). That is, the supply and the stop of the excitation current in the relay can be controlled by the excitation current control section in the equipment controller and also by the excitation current control section in the electricity storage device controller. Therefore, even when one controller of the equipment controller and the electricity storage device controller is in failure or is erroneously operated, it is possible to disconnect the relay by stopping the excitation current in the relay with the excitation current control section of the other controller. Accordingly, it is possible to improve the certainty of the stop of the excitation current in the relay, that is, the certainty of the disconnection of the relay. As a result, it is possible to improve the safety of the mounted equipment and the vehicle body in the construction machine.

Hereinafter, a hybrid hydraulic excavator as an embodiment in the present invention will be explained with reference to the accompanying drawings.

It should be noted that embodiments to be hereinafter described will be explained by taking a hybrid hydraulic excavator on which a lithium-ion cell is mounted, as an example, but the present invention is not limited thereto.

<FIG> show a first embodiment of the present invention. A hybrid hydraulic excavator <NUM> (hereinafter, that is, a traveling lever/pedal operation device, a working lever operation device (none of them is shown) and the like are provided on the periphery of the operator's seat.

The operation device outputs a pilot signal (a pilot pressure) in response to a lever operation or a pedal operation by an operator to a control valve <NUM> to be described later (see, <FIG>). As a result, the operator can operate (drive) hydraulic devices (hydraulic actuators) in the hydraulic excavator <NUM>, that is, a traveling hydraulic motor 2A, a bucket cylinder 8F, an arm cylinder 8E, a boom cylinder 8D, a revolving hydraulic motor 3A (see, <FIG>) and the like
An ignition key switch (not shown) is provided in the cab <NUM> for performing on and off operations of the power source (on and off operations of accessories) in the hydraulic excavator <NUM> and start or stop of the engine <NUM>. Further, a hybrid controller <NUM> and a main controller <NUM> to be described later (see, <FIG>) are provided in the cab <NUM> to be located in the lower side backward of the operator's seat. Meanwhile, the counterweight <NUM> is located in the rear end side of the revolving frame <NUM> to act as a weight balance to the working mechanism <NUM>.

As shown in <FIG>, the working mechanism <NUM> is configured of, for example, a boom 8A, an arm 8B and a bucket 8C as a working tool, and a boom cylinder 8D, an arm cylinder 8E and a bucket cylinder 8F as a working tool cylinder, which drive which drive the boom 8A, the arm 8B and the bucket. The boom 8A, the arm 8B and the bucket 8C are joined to each other by pin.

The working mechanism <NUM> (the boom 8A thereof) is attached to the revolving frame <NUM> in the upper revolving structure <NUM>. The working mechanism <NUM> extends or contracts the cylinders 8D, 8E, 8F to perform a lifting and tilting operation. The hydraulic excavator <NUM> travels with rotation of the traveling hydraulic motor 2A (see, <FIG>) provided on the lower traveling structure <NUM>. The upper revolving structure <NUM> revolves with rotation of the revolving hydraulic motor 3A (see, <FIG>) configuring the revolving device <NUM> together with a revolving bearing (not shown).

Here, the hydraulic excavator <NUM> is provided thereon with an electric system that controls the electric motor <NUM> and the like, and a hydraulic system that controls operations of the working mechanism <NUM> and the like. Hereinafter, an explanation will be made of the system configuration in the hydraulic excavator <NUM> with reference to <FIG> and <FIG>.

The engine <NUM> is mounted on the revolving frame <NUM>. The engine <NUM> is configured of an internal combustion engine such as a diesel engine. As shown in <FIG>, the hydraulic pump <NUM> and the electric motor <NUM> are attached mechanically to the output side of the engine <NUM> for serial connection. The hydraulic pump <NUM> and the electric motor <NUM> are driven by the engine <NUM>.

Here, the engine <NUM> is configured of an electrically controlled engine, and an operation of the engine <NUM> is controlled by an engine control unit <NUM> (hereinafter, referred to as "ECU <NUM>"). Specifically, in the engine <NUM>, a supply quantity of fuel into cylinders (combustion chambers), that is, an injection quantity of a fuel injection device (an electrically controlled injection valve) for injecting fuel into the cylinders is variably controlled by the ECU <NUM> as a control section of the engine <NUM>. In this case, the ECU <NUM> includes a microcomputer, and is connected to a main controller <NUM> (hereinafter, referred to as "MC <NUM>") to be described later.

The ECU <NUM> variably controls a fuel injection quantity into the cylinders by the fuel injection device based upon a control signal (a command signal) from the MC <NUM> to control a rotational speed of the engine <NUM>. That is, the ECU <NUM> controls an output torque, the rotational speed (engine rotational number) and the like of the engine <NUM> based upon an engine output command from the MC <NUM>. It should be noted that the maximum output of the engine <NUM> is made smaller than the maximum power of the hydraulic pump <NUM>, for example.

The hydraulic pump <NUM> is connected mechanically to the engine <NUM>. The hydraulic pump <NUM> can be driven by the torque of the engine <NUM> alone. In addition, the hydraulic pump <NUM> can be driven by a compound torque (a total torque) acquired by adding an assist torque of the electric motor <NUM> to the torque of the engine <NUM>. That is, the hydraulic pump <NUM> is driven by the mechanical power of the engine <NUM> and the electric motor <NUM>. The hydraulic pump <NUM> pressurizes hydraulic oil reserved in a tank (not shown), which is delivered to the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, the cylinders 8D, 8E and 8F of the working mechanism <NUM> as pressurized oil.

The hydraulic pump <NUM> is connected through the control valve <NUM> to the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, and the cylinders 8D, 8E and 8F in the working mechanism <NUM> as the hydraulic devices (hydraulic actuators). The hydraulic pump <NUM> is configured of a variable displacement hydraulic pump of a swash plate type, a bent axis type or a radial piston type, for example. In this case, although the illustration is omitted, the hydraulic pump <NUM> has a regulator (a variable displacement part and a tilting actuator) for regulating a pump capacity. The hydraulic pump <NUM> (the regulator thereof) is variably controlled by a command from the MC <NUM> to be described later.

The control valve <NUM> is a control valve device formed of a plurality of directional control valves, a collector of a plurality of electromagnetic valves, and the like. The control valve <NUM> distributes hydraulic oil delivered from the hydraulic pump <NUM> to the hydraulic devices of the hydraulic motors 2A, 3A, the cylinders 8D, 8E, 8F and the like. That is, the control valve <NUM> controls a direction of the pressurized oil to be delivered to the hydraulic devices 2A, 3A, 8D, 8E, 8F from the hydraulic pump <NUM> in response to lever operations and pedal operations of the traveling lever/pedal operation device and the working lever operation device located in the cab <NUM>, a command from the MC <NUM>, and the like. Thereby, the hydraulic devices 2A, 3A, 8D, 8E, 8F are driven by the pressurized oil (the hydraulic oil) to be delivered from the hydraulic pump <NUM>.

The electric motor <NUM>, also called the motor or the motor generator, is connected mechanically to the engine <NUM>. The electric motor <NUM> is configured of, for example, a synchronous electric motor and the like. The electric motor <NUM> plays two roles of power generation of performing power supply to the electricity storage device <NUM> by acting as an electric generator using the engine <NUM> as a power source, and power running of assisting in driving the engine <NUM> and the hydraulic pump <NUM> as driven bodies by acting as a motor using power from the electricity storage device <NUM> as a power source. Accordingly, the assist torque of the electric motor <NUM> is added to the torque of the engine <NUM> according to the situation, and the hydraulic pump <NUM> is driven by these torques. The traveling operation and the revolving operation of the vehicle, the tilting or the lifting operation of the working mechanism <NUM> and the like are performed by the pressurized oil delivered from the hydraulic pump <NUM>.

As shown in <FIG>, the electric motor <NUM> is connected to a pair of DC buses 18A, 18B through the inverter <NUM>. That is, the inverter <NUM> is provided between the electric motor <NUM> and the electricity storage device <NUM>, and is connected electrically to the electric motor <NUM> and the electricity storage device <NUM>. The inverter <NUM> performs conversion of power (energy conversion), and for example, is configured using a plurality of switching elements such as a transistor and an insulating gate bipolar transistor (IGBT).

On and off operation of each of the switching elements in the inverter <NUM> are controlled by a power control unit <NUM> (hereinafter, referred to as "PCU <NUM>"). The PCU <NUM> includes a microcomputer, and is connected to the hybrid controller <NUM> to be described later (hereinafter, referred to as "HC <NUM>"). The DC buses 18A, 18B are paired at a positive electrode side and at a negative electrode side, and, for example, a DC voltage of approximately several hundreds V is applied thereto.

At the power generation of the electric motor <NUM>, the inverter <NUM> converts AC power from the electric motor <NUM> into DC power, which is supplied to the electricity storage device <NUM>. At the power running operation of the electric motor <NUM>, the inverter <NUM> converts the DC power of the DC buses 18A, 18B into AC power, which is supplied to the electric motor <NUM>. The PCU <NUM> controls the on and off operation of each of the switching elements in the inverter <NUM> based upon a power generation electric motor output command from the HC <NUM>, and the like. Thereby the PCU <NUM> controls power generation at the power generation time and drive power at the power running time of the electric motor <NUM>.

The electricity storage device <NUM> is connected electrically via the inverter <NUM> to the electric motor <NUM>. In this case, the electricity storage device <NUM> is connected via the DC buses 18A, 18B to a DC side positive electrode and a DC side negative electrode of the inverter <NUM>. The electricity storage device <NUM> supplies drive power toward the electric motor <NUM> at the power running time (at the assist drive time) of the electric motor <NUM>, and is charged with power supplied from the electric motor <NUM> at the power generation time of the electric motor <NUM>. That is, the electricity storage device <NUM> supplies the power to the electric motor <NUM>, or is charged with generation power supplied from the electric motor <NUM>. In other words, the electricity storage device <NUM> performs the supply of the energy for driving the electric motor <NUM> and regeneration of the energy generated by the electric motor <NUM>.

As shown in <FIG>, the electricity storage device <NUM> is provided with a lithium-ion secondary cell <NUM> corresponding to a capacitor (including a storage cell), a current sensor <NUM>, a battery control unit <NUM> (hereinafter, referred to as "BCU <NUM>"), relays <NUM>, <NUM>, <NUM> and a resistance <NUM>, for example. The electricity storage device <NUM> is controlled by the BCU <NUM>. Specifically, a charging operation or a discharging operation of the lithium-ion secondary cell <NUM> in the electricity storage device <NUM> is controlled by the HC <NUM> based upon information from the BCU <NUM>.

Here, the lithium-ion secondary cell <NUM> is configured of an assembled battery by electrically connecting a plurality of battery cells in series or in parallel, or in series and in parallel. The current sensor <NUM> is connected to, for example, a terminal in the positive electrode side of the lithium-ion secondary cell <NUM> to detect (measure) the charging current or discharging current of the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>). An output side of the current sensor <NUM> is connected to the BCU <NUM>. The current sensor <NUM> outputs a signal in accordance with the detected current to the BCU <NUM>.

A current value detected by the current sensor <NUM> is inputted to the BCU <NUM>, and in addition thereto, a voltage and a temperature of the lithium-ion secondary cell <NUM> are inputted thereto. Therefore, for example, the lithium-ion secondary cell <NUM> is provided with a voltage sensor (not shown) detecting (measuring) a voltage of the lithium-ion secondary cell <NUM>, and a temperature sensor (not shown) detecting (measuring) a temperature of the lithium-ion secondary cell <NUM>. The output side of the voltage sensor and the output side of the temperature sensor are connected to the BCU <NUM>. The voltage sensor outputs a signal in accordance with the detected voltage to the BCU <NUM>, and the temperature sensor outputs a signal in accordance with the detected temperature to the BCU <NUM>.

The BCU <NUM> as the electricity storage device controller includes a microcomputer, and is connected to the HC <NUM> to be described later. The BCU <NUM> controls the electricity storage device <NUM>. That is, the BCU <NUM> executes predetermined calculation processing based upon a voltage and a temperature of the lithium-ion secondary cell <NUM>, and a current value measured by the current sensor <NUM>, thus carrying out the state determination, calculation and control of the lithium-ion secondary cell <NUM>.

For example, the BCU <NUM> calculates possible discharging power from the electricity storage device <NUM> as a battery discharging power, based upon the current, the voltage and the temperature. Likewise, the BCU <NUM> calculates possible charging power to the electricity storage device <NUM> as a battery charging power. The BCU <NUM> outputs a battery state of charge (SOC), a battery discharging power, a battery charging power and the like to the HC <NUM>.

In addition thereto, the BCU <NUM> monitors and estimates a state of the electricity storage device <NUM> based upon the voltage, the current, the temperature, the SOC (State of Charge), a SOH (State of Health) and the like. In a case where any index of the plurality of elements deviates or is likely to deviate from an appropriate use range, the BCU <NUM> transmits a signal to the HC <NUM> to issue abnormality alarm.

The relays <NUM>, <NUM>, <NUM> and the resistance <NUM> configure a contactor. The relays <NUM>, <NUM>, <NUM> connect or disconnect an electrical circuit (an electric equipment circuit) to which the inverter <NUM> and the electricity storage device <NUM> are connected. That is, the relays <NUM>, <NUM>, <NUM> establish the connection or disconnection between the electricity storage device <NUM> (a terminal of the lithium-ion secondary cell <NUM>) and the inverter <NUM> (a terminal in the DC side thereof). Therefore, the relays <NUM>, <NUM>, <NUM> are provided between the inverter <NUM> and the electricity storage device <NUM>. Specifically, the relays <NUM>, <NUM>, <NUM> are provided between the terminal of the lithium-ion secondary cell <NUM> and the terminal in the DC side of the inverter <NUM>.

In this case, the relays <NUM>, <NUM> are provided in parallel connection between a positive side terminal of the lithium-ion secondary cell <NUM> and a DC side positive electrode of the inverter <NUM>. The resistance <NUM> is provided in series with the relay <NUM> between the positive side terminal of the lithium-ion secondary cell <NUM> and the relay <NUM> to prevent incoming current at the relay operation. Thereby the relay <NUM> defines an incoming current preventive circuit together with the resistance <NUM>. The relay <NUM> and the relay <NUM> carry out the connection or disconnection between the positive electrode of the lithium-ion secondary cell <NUM> and the DC side positive electrode of the inverter <NUM>. Meanwhile, the relay <NUM> is provided between the negative side terminal of the lithium-ion secondary cell <NUM> and the DC side negative electrode of the inverter <NUM>. The relay <NUM> carries out the connection or disconnection between the negative electrode of the lithium-ion secondary cell <NUM> and the DC side negative electrode of the inverter <NUM>.

For example, when an unillustrated ignition key switch turns off, the relays <NUM>, <NUM>, <NUM> turn off (open), and the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are disconnected. Meanwhile, when the ignition key switch turns on by an operator, the relays <NUM>, <NUM>, <NUM> turn on (close) in response to a command from the HC <NUM>, for example, whereby the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are connected. At this time, in regard to the relays <NUM>, <NUM>, <NUM>, first, the relays <NUM>, <NUM> turn on, and then, the relay <NUM> turns on and the relay <NUM> turns off.

The HC <NUM> as the equipment controller is configured of a microcomputer, for example. The HC <NUM> is connected electrically (to be capable of communicating) to the ECU <NUM>, the PCU <NUM>, the BCU <NUM> and the MC <NUM> using a CAN (Controller Area Network) and the like. The HC <NUM> is a controller in the upper position (the upper controller) of the BCU <NUM>. Meanwhile, an operation amount sensor (not shown) is connected to the MC <NUM> to detect an operation amount of each of the traveling lever/pedal operation device and the working lever operation device that are operated by an operator, for example. The MC <NUM> also includes a microcomputer, for example.

The MC <NUM> is communicated with the ECU <NUM> and the HC <NUM>, and transmits various control signals to the ECU <NUM>, the PCU <NUM> and the HC <NUM> based upon, for example, the operation amount, the rotational speed of the engine <NUM>, the SOC of the electricity storage device <NUM>, and the like. Thereby, the ECU <NUM> controls the rotational speed of the engine <NUM> and the like based upon the control signal from the MC <NUM>. The HC <NUM> controls the hybrid equipment <NUM>, <NUM>, <NUM> based upon states of the electric motor <NUM>, the inverter <NUM> and the electricity storage device <NUM> as the hybrid equipment and information of the operation amount from the MC <NUM>. The MC <NUM> controls the hydraulic pump <NUM> (a capacity thereof) and the control valve <NUM> (a pilot pressure thereto) based upon the information of the operation amount.

That is, the MC <NUM> controls the engine <NUM> and the hydraulic pump <NUM>. In addition thereto, the MC <NUM> controls the control valve <NUM> to control the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, and the cylinders 8D, 8E, 8F in the working mechanism <NUM>, as the hydraulic devices. The HC <NUM> controls the electricity storage device <NUM> and the inverter <NUM> and performs coordination control with the MC <NUM>. The HC <NUM> performs the coordination control with the MC <NUM> and controls the electric motor <NUM>, the inverter <NUM> and the BCU <NUM>.

Incidentally according to the conventional technology as described before, the relay disconnecting the electrical circuit is controlled by the single controller. Therefore, for example, in a case where the controller dealing with the control of the relay is in failure or is erroneously operated, the excitation current in the relay cannot be stopped, creating a possibility of being incapable of disconnecting the relay. This is not preferable, for example, since in the lithium-ion secondary cell <NUM> requiring accurate control of the voltage, the current and the temperature, the abnormal state of the overcharge, the over-discharge, the overtemperature or the like is possibly in progress.

On the other hand, the first embodiment is configured to be capable of controlling the supply and the stop of the excitation current in the relay <NUM> with the HC <NUM> as the equipment controller and further, to be capable of controlling the supply and the stop of the excitation current in the relay <NUM> with the BCU <NUM> also as the electricity storage device controller. Therefore, an explanation will be made of the control of the relay <NUM> in the first embodiment with reference to <FIG> in addition to <FIG>.

<FIG> shows a relay control circuit. The first embodiment will be explained by taking the relay control circuit for controlling the supply and the stop of the excitation current in the relay <NUM> in the negative electrode side in the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>), as an example. The relay control circuit is, however, not limited thereto, but may be configured to control the supply and the stop of the excitation current in the relay <NUM> (and the relay <NUM> as needed) in the positive electrode side in the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>). Further, the relay control circuit may be configured to control the supply and the stop of the excitation current in the relays <NUM>, <NUM> (and the relay <NUM> as needed) in both of the negative electrode side and the positive electrode side in the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>).

In <FIG>, a power source <NUM> is a power source as a supply source of the relay excitation current, and for example, can use an in-vehicle battery of 12V, 24V or the like for accessory drive, which is mounted in the hydraulic excavator <NUM>. The power source <NUM> is connected to an excitation circuit 25A in the relay <NUM>. The relay <NUM> is connected to the DC side negative electrode of the inverter <NUM> and the negative electrode of the lithium-ion secondary cell <NUM>. The relay <NUM> is connected or disconnected by the relay excitation current from the power source <NUM>.

That is, the relay <NUM> closes (turns on) when the relay excitation current is supplied to the excitation circuit 25A (an excitation coil) from the power source <NUM> (when the excitation circuit 25A is in power supply), and the negative side of the lithium-ion secondary cell <NUM> is connected to the DC side negative electrode of the inverter <NUM>. On the other hand, the relay <NUM> opens (turns off) when the supply of the relay excitation current to the excitation circuit 25A from the power source <NUM> is stopped (when the excitation circuit 25A is in non-power supply), and the negative side of the lithium-ion secondary cell <NUM> is disconnected to the DC side negative electrode of the inverter <NUM>.

An excitation current control section configured to control the supply and the stop of the excitation current in the relay <NUM> is provided in each of the HC <NUM> and the BCU <NUM>. That is, in the first embodiment, the HC <NUM> and the BCU <NUM> each have the excitation current control section configured to control the supply and the stop of the excitation current in the relay <NUM>. The excitation current control section is configured of switches, specifically FET switches <NUM>, <NUM> as field-effect transistor switches for switching the supply and the stop of the excitation current in the relay <NUM>. The BCU <NUM> is provided with the first FET switch <NUM> as the excitation current control section, and the HC <NUM> is provided with the second FET switch <NUM> as the excitation current control section. That is, the BCU <NUM> as the electricity storage device controller has the first FET switch <NUM> as the relay control section for controlling the supply and the stop of the operating current in the relay <NUM>. The HC <NUM> as the upper controller has the second FET switch <NUM> as the relay control section for controlling the supply and the stop of the operating current in the relay <NUM>.

The first FET switch <NUM> installed (mounted) in the BCU <NUM> and the second FET switch <NUM> installed (mounted) in the HC <NUM> are connected in series. That is, the first FET switch <NUM> is provided in the BCU <NUM> with a drain terminal connected to the excitation circuit 25A in the relay <NUM>. The second FET switch <NUM> is provided in the HC <NUM> with a drain terminal connected to the FET switch <NUM> in the BCU <NUM> and with a source terminal connected to a GND <NUM> (the vehicle body or the like) as the ground. A pair of diodes <NUM> are positioned between the first FET switch <NUM> and the second FET switch <NUM> and are provided in parallel connection in the HC <NUM> as a reverse flow preventive device for preventing a reverse flow of the current.

The first FET switch <NUM> switches in turning on or off by the BCU <NUM>. The second FET switch <NUM> switches in turning on or off by the HC <NUM>. When the first FET switch <NUM> and the second FET switch <NUM> both turn on (close), the relay excitation current is supplied via the power source <NUM> to the excitation circuit 25A, and the relay <NUM> turns on (closes). Meanwhile, when at least one of the first FET switch <NUM> and the second FET switch <NUM> turns off (opens), the relay excitation current to the excitation circuit 25A is stopped, and the relay <NUM> turns off (opens).

The first FET switch <NUM> and the second FET switch <NUM> each are provided in the controllers (the BCU <NUM> and the HC <NUM>), but may be provided outside of the controllers. The FET switch and the controller each configured to control the FET switch may comprise two or more ones. For example, a controller in addition to the BCU <NUM> and the HC <NUM>, that is, a third FET switch may be provided in the MC <NUM> (in serial connection to the first FET switch <NUM> and the second FET switch <NUM>). In addition, the PCU <NUM> as the controller of the inverter <NUM> may be provided with the third FET switch. Further, the third FET switch may be provided in a controller (not shown) specialized in control at the abnormal time of the relay disconnection, for example.

In the first embodiment, the first FET switch <NUM> and the second FET switch <NUM> both are located between the excitation circuit 25A in the relay <NUM> and the GND <NUM>, but, for example, may be located between the power source <NUM> and the excitation circuit 25A in the relay <NUM>. In addition, any of the first FET switch <NUM> and the second FET switch <NUM> may be located between the power source <NUM> and the excitation circuit 25A in the relay <NUM>, and the other may be located between the excitation circuit 25A in the relay <NUM> and the GND <NUM>. Further, in the first embodiment, the field-effect transistor switch is used as the switch, but for example, another switching device such as a bipolar transistor or the like may be used.

In any case, in the first embodiment, the two FET switches <NUM>, <NUM> each are provided in the BCU <NUM> and the HC <NUM>, and the two FET switches <NUM>, <NUM> are in series connected. In a case where the BCU <NUM> determines that a state of the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) is an abnormal state of requiring the stop of the excitation current in the relay <NUM>, the BCU <NUM> transmits an abnormal signal to the HC <NUM>. That is, the BCU <NUM> has an electricity storage device abnormal state notifying section <NUM> configured to notify (inform) the HC <NUM> of the abnormal state of the electricity storage device <NUM>. In addition thereto, the BCU <NUM>, when a predetermined time T has elapsed after transmitting the abnormal signal, turns off (opens) the first FET switch <NUM> of the BCU <NUM> regardless of the state of the relay <NUM>. That is, whether the second FET switch <NUM> in the HC <NUM> turns off (opens) or turns on (closes), the excitation current in the relay <NUM> is stopped by turning off (opens) the first FET switch <NUM> in the BCU <NUM>.

In this case, the predetermined time T can be in advance set as a time required for the HC <NUM> to make the current of the inverter <NUM>, finally the current of the electric motor <NUM> be zero. That is, the predetermined time T can be in advance set as a time slightly longer than a time required for the HC <NUM> to null output of the inverter <NUM> (a time required for turning off a gate of IGBT and nulling inverter output), such as approximately several hundred milliseconds to one second.

On the other hand, the HC <NUM> turns off (opens) the second FET switch <NUM> in the HC <NUM> after executing the stop processing based upon the abnormal signal from the BCU <NUM>, and thereby stops the excitation current in the relay <NUM> and transmits a signal of the state of the relay <NUM> (for example, the effect that the relay <NUM> opens) to the other controller (for example, the MC <NUM>, the BCU <NUM> or the like). In this case, the stop processing of the HC <NUM> is processing of cutting off the current in the electrical equipment circuit (the electric equipment circuit) to zero. For example, the stop processing of the HC <NUM> is the processing of outputting a stop command to the PCU <NUM>, nulling the output of the inverter <NUM> and cutting off the current of the electric motor <NUM> to zero. The control by the BCU <NUM> and the HC <NUM>, that is, the control processing of the HC <NUM> shown in <FIG> and the control processing of the BCU <NUM> shown in <FIG> will be in detail explained later.

The hydraulic excavator <NUM> according to the first embodiment has the configuration as described above, and next, an operation thereof will be explained.

When an operator who has got in the cab <NUM> activates the engine <NUM>, the hydraulic pump <NUM> and the electric motor <NUM> are driven by the engine <NUM>. Thereby, the hydraulic oil delivered by the hydraulic pump <NUM> is delivered to the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, and the boom cylinder 8D, the arm cylinder 8E and the bucket cylinder 8F in the working mechanism <NUM> in response to the lever operation and the pedal operation of the traveling lever/pedal operation device and the working lever operation device provided in the cab <NUM>. Thereby, the hydraulic excavator <NUM> can perform the traveling operation by the lower traveling structure <NUM>, the revolving operation of the upper revolving structure <NUM>, the excavating operation of the working mechanism <NUM>, and the like.

Here, when the output torque of the engine <NUM> is larger than the drive torque of the hydraulic pump <NUM> at the operating of the hydraulic excavator <NUM>, the electric motor <NUM> is driven as a power generator by the extra torque. Thereby, the electric motor <NUM> generates AC power, and the AC power is converted into DC power by the inverter <NUM>, which is stored in the electricity storage device <NUM>. Meanwhile, when the output torque of the engine <NUM> is smaller than the drive torque of the hydraulic pump <NUM>, the electric motor <NUM> is driven as an electric motor by the power from electricity storage device <NUM>, which assists in a drive of the engine <NUM>. At this time, the first FET switch <NUM> of the BCU <NUM> and the second FET switch <NUM> of the HC <NUM> both turn on (close), creating a state where the excitation current is supplied to the excitation circuit 25A in the relay <NUM>, that is, the relay <NUM> is in the connection state.

Next, an explanation will be made of the control processing of the relay <NUM> by the HC <NUM> and the BCU <NUM> with reference to <FIG> and <FIG>. Here, <FIG> shows the control processing of the HC <NUM>. <FIG> shows the control processing of the BCU <NUM>. Each step in the flow charts shown in <FIG> and <FIG> uses notation of "S" (for example, step <NUM> = "S1").

First, an explanation will be made of the control processing of the HC <NUM> as shown in <FIG>. The ignition key switch turns on and the activation processing in the hydraulic excavator <NUM> is executed. Thereby, when the control processing in <FIG> is started, the HC <NUM> executes regular control processing in S1. In the regular control processing, the HC <NUM> executes regular control of the electric equipment. That is, the HC <NUM> executes control (predetermine control) when the inverter <NUM> as the electric equipment and the electricity storage device <NUM> are normal. Along with it, the HC <NUM> executes processing of S2 to S4 as well. The processing of S2 to S4 is processing for observation and determination on whether an operation of various equipment is normal or abnormal.

That is, the HC <NUM> monitors all of the equipment (electric equipment) in an electric system including the electricity storage device <NUM>. In addition, in S2, soft abnormality is mainly detected. That is, in S2 it is determined whether or not the monitored items of the HC <NUM> are normal. For example, it is determined whether or not a calculation value of the HC <NUM> is within an allowable range (a control range). In other words, it is determined whether or not the control of the HC <NUM> itself is within a normal range.

In S3, it is determined whether or not a state of the electric equipment, that is, states of the electricity storage device <NUM> and the inverter <NUM> are normal. That is, in S3, the HC <NUM> determines whether or not the reports from the BCU <NUM> and the inverter <NUM> are normal. For example, the HC <NUM> determines whether or not a physical numerical value (a detection value) of the electricity storage device <NUM> obtained from the BCU <NUM> in the electricity storage device <NUM> and a physical numerical value (a detection value) of the inverter <NUM> obtained from the PCU <NUM> in the inverter <NUM> each are within an allowable range (a normal range and a control range). In S4, it is determined whether or not a communication connection state is normal. That is, the HC <NUM> determines whether or not the communication connection state between the BCU <NUM>, the PCU <NUM> and the MC <NUM> is normal.

In a case where "YES" is made in determination in S2 to S4, that is, each state is determined to be normal in the determination on whether to be normal, the process goes to S5. In S5, it is determined whether or not the ignition key switch is in an off state. In a case where in S5 "NO" is made, that is, in a case where it is determined that the ignition key switch is in an on state, the process goes back to S1, and the processing subsequent to S1 is repeated. Meanwhile, in a case where "YES" is made in determination in S5, that is, in a case where it is determined that the ignition key switch in the normal state (in a case where no abnormal determination is made) is in the off state, the process goes to S6.

In S6, electric equipment control stop processing is executed. That is, the HC <NUM> cuts off the current flowing in the electric equipment circuit to zero. For example, the HC <NUM> outputs a command of setting the output of the inverter <NUM> to an off state to the PCU <NUM> to cut off the current of the electric motor <NUM> to zero. When the current flowing in the electric equipment circuit is cut off to zero in S6, the relay is disconnected in S7. That is, the HC <NUM> turns off (opens) the second FET switch <NUM> in the HC <NUM> to disconnect the relay <NUM>. Thereby, in S8, the electric equipment stops, and then, the HC <NUM> becomes in the stop state.

On the other hand, in a case where "NO" is made in determination in S2 to S4, that is, each state is determined to be not normal (abnormal) in the determination on whether to be normal, the process goes to S11. In S11, abnormality alarm is issued. For example, the HC <NUM> transmits a signal (an abnormal signal) that the abnormality occurs, to the BCU <NUM>, the PCU <NUM> and the MC <NUM>. In subsequent S12, the electric equipment control stop processing is executed. That is, the HC <NUM>, as similar to the processing in S6, cuts off the current flowing in the electric equipment circuit to zero. For example, the HC <NUM> outputs a command of setting the output of the inverter <NUM> to the off state to the PCU <NUM> to cut off the current of the electric motor <NUM> to zero.

When the current flowing in the electric equipment circuit is cut off to zero in S12, the relay is disconnected in S13. That is, in S13, as similar to the processing in S7, the HC <NUM> turns off (opens) the second FET switch <NUM> in the HC <NUM> to disconnect the relay <NUM>. When the relay <NUM> is disconnected in S13, the relay state is transmitted in subsequent S14. That is, in S14 the HC <NUM> transmits the effect that the relay <NUM> is disconnected, to the BCU <NUM>, for example.

When the relay <NUM> is disconnected in S13, the electric equipment stops in S15 subsequent to S14. In this state, the electric equipment is stopped, but the hydraulic equipment control becomes in the continuing hydraulic mode. In this hydraulic mode, a vehicle body operation by the hydraulic power is made possible. That is, the hydraulic pump <NUM> is operating by the engine <NUM> alone, and the hydraulic excavator <NUM> is operable by the hydraulic oil to be delivered from the hydraulic pump <NUM>.

In S16 subsequent to S15, it is determined whether or not the ignition key switch is in the off state. In a case where in S16 "NO" is made, that is, the ignition key switch is determined to be in the on state, the process goes back to S15, and the processing subsequent to S15 is repeated. Meanwhile, in a case where "YES" is made in determination in S16, that is, the ignition key switch is determined to be in the off state, the HC <NUM> stops.

Next, an explanation will be made of the control processing of the BCU <NUM> as shown in <FIG>. The ignition key switch becomes in the on state and the activation processing in the hydraulic excavator <NUM> is executed. Thereby, when the control processing in <FIG> is started, the BCU <NUM> executes regular control processing in S21. In the regular control processing, the BCU <NUM> executes regular control of the electricity storage device <NUM>. That is, the BCU <NUM> executes the control (predetermined control) when the electricity storage device <NUM> is normal. Along with it, the BCU <NUM> executes processing of S22 to S24 as well. The processing of S22 to S24 is processing for observation and determination on whether the electricity storage device <NUM> is normal or abnormal.

That is, the BCU <NUM> monitors information in regard to the electricity storage device <NUM>. In this case, in S22 it is determined whether or not the monitored items of the BCU <NUM> are normal. For example, it is determined whether or not each of a voltage, a current, a temperature, an SOC and a SOH of the lithium-ion secondary cell <NUM> is within an allowable range (a normal range). In S23, it is determined whether or not a report from the HC <NUM> is normal. That is, the BCU <NUM> and the HC <NUM> notify abnormality to each other. In S23, it is determined whether or not the BCU <NUM> receives a normal signal from the HC <NUM> (in other words, whether to receive an abnormal signal). In S24, it is determined whether or not the communication connection state is normal. That is, the BCU <NUM> determines whether or not the communication connection state to the HC <NUM> is normal.

In a case where "YES" is made in determination in S22 to S24, that is, each state is determined to be normal in the determination on whether to be normal, the process goes to S25. In S25, it is determined whether or not the ignition key switch is in an off state. In a case where in S25 "NO" is made, that is, the ignition key switch is determined to be in an on state, the process goes back to S21, and the processing subsequent to S21 is repeated. Meanwhile, in a case where "YES" is made in determination in S25, that is, in a case where it is determined that the ignition key switch in the normal state (in a case where no abnormal determination is made) is in the off state, the process goes to S26.

In S26, termination processing of the BCU <NUM> is executed. For example, in S26, the BCU <NUM> executes termination processing of storage (memory) of data in the lithium-ion secondary cell <NUM>, or the like. When the termination processing of the BCU <NUM> is executed in S26, the relay disconnection is made in S27. That is, in S27, the BCU <NUM> turns off (opens) the first FET switch <NUM> in the BCU <NUM> to disconnect the relay <NUM>. When the relay <NUM> is disconnected in S27, the BCU <NUM> becomes in the stop state.

On the other hand, in a case where "NO" is made in determination in S22 to S24, that is, each state is determined to be not normal (abnormal) in the determination on whether to be normal, the process goes to S31. In S31, abnormality alarm is issued. For example, the BCU <NUM> transmits a signal (an abnormal signal) of the effect that the abnormality is present, to the HC <NUM> (the electricity storage device abnormal state notifying section <NUM>). In subsequent S32, timer processing is executed. That is, in S32, the BCU <NUM> determines whether or not a predetermined time T has elapsed after it is determined that the BCU <NUM> is not normal (abnormal) (in other words, after the abnormality alarm is issued). In this case, the predetermined time T can be set as a time required for the HC <NUM> to cut off the current of the electric motor <NUM> to zero.

When the process waits for the predetermined time T in S32 (when the predetermined time T has elapsed), the process goes to S33, wherein the relay disconnection is performed. That is, in S33, the BCU <NUM> disconnects the relay <NUM> by turning off (opening) the first FET switch <NUM> of the BCU <NUM>.

In S34 subsequent to S33, it is determined whether or not the ignition key switch is in the off state. In a case where in S34 "NO" is made, that is, the ignition key switch is determined to be in the on state, the process goes back before S34, and the processing subsequent to S34 is repeated. Meanwhile, in a case where "YES" is made in determination in S34, that is, the ignition key switch is determined to be in the off state, the process goes to S35, wherein the terminal processing of the BCU <NUM> is executed. For example, in S36, the BCU <NUM> executes the terminal processing of the storage (the memory) of the data in the lithium-ion secondary cell <NUM>, and the like. In S36, when the terminal processing of the BCU <NUM> is executed, the BCU <NUM> becomes in the stop state.

<FIG> shows regular abnormal processing in time series in a case where the HC <NUM> disconnects the relay <NUM>. For example, in the electric equipment state, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) rises in temperature to be in an overtemperature abnormal state (an electricity storage cell overtemperature abnormal state), the BCU <NUM> transitions to the abnormal state to issue the abnormality as communication information. At this time, the timer processing starts at the same time. That is, when "NO" is determined in S22 in <FIG>, the BCU <NUM> issues abnormality alarm in S31 and starts the timer processing in S32.

Meanwhile, the HC <NUM> transitions to the abnormal state by the communication information (abnormality alarm issue) of the BCU <NUM>, and executes the stop processing of the electric equipment control, and cuts off the current of the electric equipment circuit to zero. After that, the second FET switch <NUM> mounted in the HC <NUM> is made to turn off to disconnect the relay <NUM>. That is, when "NO" is determined in S3 in <FIG>, the HC <NUM> executes the stop processing in S12 to cut off the current of the electric equipment circuit to zero. After that, the second FET switch <NUM> mounted on the HC <NUM> is caused to turn off by the processing in S13 to disconnect the relay <NUM>.

When the timer processing is completed after the relay <NUM> is disconnected by the HC <NUM>, the BCU <NUM> turns off the first FET switch <NUM> mounted on the BCU <NUM>. That is, when the timer processing in S32 in <FIG> is completed (terminated), the BCU <NUM> turns off the first FET switch <NUM> in S33. In this case, since the relay <NUM> is already disconnected by the second FET switch <NUM> mounted in the HC <NUM>, the state of the relay <NUM> has no change.

In this way, the timer processing (S32 in <FIG>) is executed from the abnormal state of the BCU <NUM> to the relay disconnection in the regular abnormal processing. Accordingly, by stopping the electric equipment control in the meanwhile (in the middle of timer processing) by the HC <NUM>, the relay <NUM> can be disconnected after setting the current of the electrical equipment circuit to zero. Therefore, it is possible to suppress relay damages due to a back electromotive force or arc discharge at the time of disconnecting the relay <NUM>.

Meanwhile, <FIG> shows abnormal processing in an emergency in time series in a case where the BCU <NUM> disconnects the relay <NUM>. For example, in the electric equipment state, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) rises in temperature to be in an overtemperature abnormal state (an electricity storage cell overtemperature abnormal state), the BCU <NUM> transitions to the abnormal state to issue the abnormality alarm as communication information. At this time, the timer processing starts at the same time. That is, when "NO" is determined in S22 in <FIG>, the BCU <NUM> issues the abnormality alarm in S31 and starts the timer processing in S32.

At this time, in a case where the HC <NUM> cannot turn off the second FET switch <NUM> mounted on the HC <NUM> due to a failure, an erroneous operation or the like, for example, the BCU <NUM> in which the timer processing is completed turns off the first FET switch <NUM> mounted on the BCU <NUM> to disconnect the relay <NUM>. In this way, in an emergency in which the regular relay disconnection cannot be performed by the HC <NUM>, the BCU <NUM> performs the relay disconnection regardless of the presence or absence of the current in the electric equipment circuit to stop the operation of the electric equipment. Accordingly, it is possible to suppress the lithium-ion secondary cell <NUM> in the electricity storage device <NUM> from being in progress in the abnormal state such as overcharging, over-discharging, or overtemperature. As a result, it is possible to improve the safety.

In this way, in the first embodiment, the HC <NUM> as the equipment controller and the BCU <NUM> as the electricity storage device controller each include the first FET switch <NUM> and the second FET switch <NUM> that are the switches as the excitation current control section. That is, the supply and the stop of the excitation current of the relay <NUM> can be controlled by the second FET switch <NUM> of the HC <NUM> and also by the first FET switch <NUM> of the BCU <NUM>. Therefore, even when one controller of the HC <NUM> and the BCU <NUM> is in failure or is erroneously operated, it is possible to disconnect the relay <NUM> by stopping the excitation current in the relay <NUM> with the switch (the first FET switch <NUM> or the second FET switch <NUM>) of the other controller. Accordingly, it is possible to improve the certainty of the stop of the excitation current in the relay <NUM>, that is, the certainty of the disconnection of the relay <NUM>. As a result, it is possible to improve the safety of the mounted equipment (for example, the electricity storage device <NUM>, the electric motor <NUM>, and the inverter <NUM>) and the vehicle body in the hydraulic excavator <NUM> as the construction machine.

In the first embodiment, in a case where the BCU <NUM> determines that the electricity storage device <NUM> is in the abnormal state, when the predetermined time T has elapsed, the excitation current in the relay <NUM> is stopped by the first FET switch <NUM> of the BCU <NUM> regardless of the state of the relay <NUM>. Therefore, when the predetermined time T has elapsed after the BCU <NUM> determines that the electricity storage device <NUM> is in the abnormal state, the excitation current in the relay <NUM> can be stopped by the first FET switch <NUM> in the BCU <NUM> regardless of the failure or the erroneous operation of the HC <NUM>. That is, even when the HC <NUM> cannot stop the excitation current in the relay <NUM> by the second FET switch <NUM> due to the failure or the erroneous operation of the HC <NUM>, it is possible to stop the excitation current in the relay <NUM> by the first FET switch <NUM> in the BCU <NUM> when the predetermined time T has elapsed. Thereby, it is possible to improve the certainty of the stop of the excitation current in the relay <NUM>. Even when the second FET switch <NUM> is in failure or is erroneously operated, it is possible to stop the excitation current in the relay <NUM> by the first FET switch <NUM> in the BCU <NUM>.

In the first embodiment, the field-effect transistors of N channels are used as the first FET switch <NUM> and the second FET switch <NUM>. In this case, although the illustration is omitted, it is preferable to provide the configuration of the following (<NUM>) to (<NUM>) in a circuit in <FIG>.

In the first embodiment, the HC <NUM> executes the stop processing based upon the abnormal signal from the BCU <NUM>, and thereafter, stops the excitation current in the relay <NUM> by the second FET switch <NUM> of the HC <NUM>. That is, the HC <NUM> executes the stop processing, and thereafter, stops the excitation current in the relay <NUM>. Therefore, by the stop processing of the HC <NUM> the current of the electrical equipment circuit is made to zero, and after that, the excitation current in the relay <NUM> is stopped, thus making it possible to disconnect the relay <NUM>. Thereby, it is possible to suppress the relay damage due to the back electromotive force or the arc discharge at the relay disconnection. Further, the HC <NUM> transmits a signal of the relay state. Therefore, it is possible to notify the other controller (for example, the BCU <NUM>) that the relay <NUM> is disconnected by the second FET switch <NUM> of the HC <NUM>.

In the first embodiment, the relay <NUM> the connection and the disconnection of which are controlled by both of the HC <NUM> and the BCU <NUM> is provided between the electricity storage device <NUM> (the lithium-ion secondary cell <NUM> thereof) and the inverter <NUM>. That is, the relay <NUM> is provided in the electrical circuit including the electricity storage device <NUM> (the lithium-ion secondary cell <NUM> thereof) as the power source and the inverter <NUM>, and the relay <NUM> disconnects the electricity storage device <NUM> and the inverter <NUM>. Therefore, the relay <NUM> can stop the power supply to the inverter <NUM> by disconnecting the electricity storage device <NUM> and the inverter <NUM>.

In the first embodiment, the hydraulic excavator <NUM> is composed of the hybrid construction machine provided with the engine <NUM> connected mechanically to the electric motor <NUM>. That is, the hydraulic pump <NUM> is driven by the engine <NUM> and the electric motor <NUM>. The electricity storage device <NUM> supplies the power to the electric motor <NUM>, and is charged with the generated power by the electric motor <NUM>. The MC <NUM> controls the engine <NUM>, the hydraulic pump <NUM>, and the control valve <NUM> (via the control valve <NUM> the MC <NUM> controls the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, and the cylinders 8D, 8E, 8F of the working mechanism <NUM> as the hydraulic devices). Therefore, it is possible to improve the safety of the mount equipment and the vehicle body in the hybrid hydraulic excavator <NUM>.

Next, <FIG> shows a second embodiment. The second embodiment is characterized in that an excitation current control section in an equipment controller and an excitation current control section in an electricity storage device controller change switches through an AND circuit. It should be noted that in the second embodiment, components identical to those in the first embodiment are referred to as identical reference numerals, and the explanation is omitted.

A single FET switch <NUM> is provided between the excitation circuit 25A in the relay <NUM> and the GND <NUM>. The FET switch <NUM> has a drain terminal connected to the excitation circuit 25A in the relay <NUM> and a source terminal connected to the GND <NUM>. The FET switch <NUM> is a switch for switching the supply and the stop of the excitation current in the relay <NUM>.

An HC <NUM> and a BCU <NUM> are connected via an AND circuit <NUM> to the FET switch <NUM>. As similar to the HC <NUM> in the first embodiment, the HC <NUM> controls the electric motor <NUM>, the inverter <NUM>, and the BCU <NUM>. As similar to the BCU <NUM> in the first embodiment, the BCU <NUM> also controls the electricity storage device <NUM>.

Here, an excitation current control section 42A in the HC <NUM> outputs <NUM> (high) to the AND circuit <NUM> when the relay <NUM> is caused to turn on (close), that is, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are connected. On the other hand, for example, when the relay <NUM> is caused to turn off (open) by the processing in S7 or in S13 in <FIG>, that is, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are disconnected, the excitation current control section 42A in the HC <NUM> outputs <NUM> (low) to the AND circuit <NUM>.

Here, an excitation current control section 43A in the BCU <NUM> outputs <NUM> (high) to the AND circuit <NUM> when the relay <NUM> is caused to turn on (close), that is, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are connected. On the other hand, for example, when the relay <NUM> is caused to turn off (open) by the processing in S27 or in S33 in <FIG>, that is, when the electricity storage device <NUM> (the lithium-ion secondary cell <NUM>) and the inverter <NUM> are disconnected, <NUM> (low) is outputted to the AND circuit <NUM>.

When <NUM> is outputted to the AND circuit <NUM> from both of the excitation current control section 42A in the HC <NUM> and the excitation current control section 43A in the BCU <NUM>, <NUM> is outputted to the FET switch <NUM>. Meanwhile, when <NUM> is outputted from at least one excitation current control section 42A or 43A of the excitation current control section 42A in the HC <NUM> and the excitation current control section 43A in the BCU <NUM>, <NUM> is outputted to the FET switch <NUM>. When <NUM> is inputted to the FET switch <NUM> from the AND circuit <NUM>, the FET switch <NUM> turns on (closes), and When <NUM> is inputted to the FET switch <NUM> from the AND circuit <NUM>, the FET switch <NUM> turns off (opens).

In this way, in the second embodiment also, as similar to the first embodiment, the HC <NUM> and the BCU <NUM> each have the excitation current control sections 42A, 43A configured to control the supply and the stop of the excitation current in the relay <NUM>. In this case, in the second embodiment, the excitation current control section 42A in the HC <NUM> is configured as a command output section that outputs a command signal for turning on or off (closing or opening) the relay <NUM> to the FET switch <NUM> via the AND circuit <NUM>. In addition, the excitation current control section 43A in the BCU <NUM> also is configured as a command output section that outputs a command signal for turning on or off (closing or opening) the relay <NUM> to the FET switch <NUM> via the AND circuit <NUM>.

The second embodiment is configured to switch the FET switch <NUM> via the AND circuit <NUM> by the excitation current control section 42A in the HC <NUM> and the excitation current control section 43A in the BCU <NUM> as described above, and does not differ particularly in the basic function from the first embodiment as described before.

That is, in the second embodiment also, the supply and the stop of the excitation current in the relay <NUM> can be controlled by the excitation current control section (the command output section) 42A in the HC <NUM> and also by the excitation current control section (the command output section) 43A in the BCU <NUM>. Therefore, even when one controller of the HC <NUM> and the BCU <NUM> is in failure or is erroneously operated, it is possible to disconnect the relay <NUM> by stopping the excitation current in the relay <NUM> with the excitation current control section (the command output section) 42A or 43A of the other controller. Accordingly, it is possible to improve the certainty of the stop of the excitation current in the relay <NUM>, that is, the certainty of the disconnection of the relay <NUM>.

It should be noted that in <FIG>, the FET switch <NUM> and the AND circuit <NUM> are provided to be separate from the HC <NUM> and the BCU <NUM>. However, not limited thereto, the FET switch <NUM> and the AND circuit <NUM> may be provided within the HC <NUM> or the BCU <NUM>, for example.

Next, <FIG> shows a third embodiment. The third embodiment is characterized in that a hydraulic excavator as a construction machine is an electric hydraulic excavator. It should be noted that in the third embodiment, components identical to those in the first embodiment are referred to as identical reference numerals, and the explanation is omitted.

The electric motor <NUM> drives the hydraulic pump <NUM> as a driven body. The electricity storage device <NUM>, as similar to the first embodiment, supplies power via the inverter <NUM> to the electric motor <NUM>. In this case, as shown in <FIG> and <FIG> in the first embodiment, in the third embodiment also, the electricity storage device <NUM> is electrically connected via the relay <NUM> to the inverter <NUM>. The inverter <NUM> converts the power supplied from the electricity storage device <NUM> to be supplied to the electric motor <NUM>. The relay <NUM> is provided between the electricity storage device <NUM> and the inverter <NUM> to electrically connect or disconnect the electricity storage device <NUM> and the inverter <NUM>.

The MC <NUM> controls the hydraulic pump <NUM>. In addition thereto, the MC <NUM> controls the control valve <NUM> to control the traveling hydraulic motor 2A, the revolving hydraulic motor 3A, and the cylinders 8D, 8E, 8F of the working mechanism <NUM> as the hydraulic devices. An electric equipment controller <NUM> (hereinafter, referred to as "EC <NUM>") as the equipment controller performs coordination control with the MC <NUM> and controls the electric motor <NUM>, the inverter <NUM> and the BCU <NUM>. The EC <NUM>, as similar to the equipment controller (the HC <NUM>) in the first embodiment, responds to the upper controller provided with the relay control section (the second FET switch <NUM>) for controlling the supply and the stop of the operating current in the relay <NUM>. The upper controller (the EC <NUM> in <FIG>, and the HC <NUM> in <FIG> as described before) communicates with the BCU <NUM>.

The BCU <NUM> is the controller of the electricity storage device <NUM>, that is, the electricity storage device controller that manages the state of the electricity storage device <NUM>. In the third embodiment also, as similar to the first embodiment, the BCU <NUM> and the upper controller (the EC <NUM>) each have the relay control sections (the first FET switch <NUM> and the second FET switch <NUM>) for controlling the supply and the stop of the operating current in the relay <NUM>. That is, the BCU <NUM> includes the electricity storage device abnormal state notifying section <NUM> configured to, when the electricity storage device <NUM> becomes in the abnormal state of electrically disconnecting the electricity storage device <NUM> and the inverter <NUM> by the relay <NUM>, notify the upper controller (the EC <NUM>) of the abnormal state of the electricity storage device <NUM>. In addition thereto, the BCU <NUM> includes the relay control section (the first FET switch <NUM>) configured to, when the electricity storage device <NUM> becomes in the abnormal state, stop the supply of the operating current in the relay <NUM> regardless of the supply of the operating current of the relay <NUM> is stopped by the upper controller (the EC <NUM>) notifying the abnormal state of the electricity storage device <NUM>.

The relay control section (the first FET switch <NUM>) of
the BCU <NUM>, as similar to the first embodiment, stops the supply of the operating current in the relay <NUM> after the predetermined time T has elapsed after notifying the upper controller (the EC <NUM>) of the abnormal state of the electricity storage device <NUM>. In this case, the predetermined time T is set to be longer than a time from a point where the abnormal state of the electricity storage device <NUM> is notified until a point where the current flowing between the electricity storage device <NUM> and the electric motor <NUM> becomes zero by the disconnection of the relay <NUM>, or a time until a point where the supply of the operating current in the relay <NUM> is stopped by the relay control section (the second FET switch <NUM>) of the upper controller (the EC <NUM>).

Therefore, in the third embodiment also, as similar to the first embodiment, the EC <NUM> and the BCU <NUM> each have the excitation current control sections (the first FET switch <NUM> and the second FET switch <NUM>) configured to control the supply and the stop of the excitation current in the relay <NUM>. That is, in the third embodiment, the EC <NUM> has the second FET switch <NUM> as the excitation current control as similar to the HC <NUM> in the first embodiment.

The third embodiment is configured to control the supply and the stop of the excitation current in the relay <NUM> with the second FET switch <NUM> of the EC <NUM> and the first FET switch <NUM> of the BCU <NUM> as described above, and does not differ particularly in the basic function from the first embodiment as described above. That is, the third embodiment also, as similar to the first embodiment, even when one controller of the EC <NUM> and the BCU <NUM> is in failure or is erroneously operated, can disconnect the relay <NUM> by stopping the excitation current in the relay <NUM> with the switches (the first FET switch <NUM> and the second FET switch <NUM>) of the other controller.

The first embodiment is explained by taking a case where the relay <NUM> provided between the negative side terminal of the lithium-ion secondary cell <NUM> and the DC side negative electrode of the inverter <NUM> can be disconnected by both of the HC <NUM> and the BCU <NUM>, as an example. However, not limited thereto, the relay <NUM> (and the relay <NUM> as needed) provided between the positive side terminal of the lithium-ion secondary cell <NUM> and the DC side positive electrode of the inverter <NUM> may be disconnected by both of the HC <NUM> and the BCU <NUM>. In addition, the relays <NUM>, <NUM> (and the relay <NUM> as needed) may be disconnected by both of the HC <NUM> and the BCU <NUM>. This configuration can be likewise applied to the second embodiment and the third embodiment.

The first embodiment is explained by taking a case of using the lithium-ion secondary cell <NUM> in the electricity storage device <NUM>, as an example, but another secondary cell (for example, a nickel cadmium battery or nickel hydrogen battery) or a capacitor that can supply necessary power may be used. A step-up and-down device such as a DC-DC converter may be provided between an electricity storage device and a DC bus. This configuration can be likewise applied to the second embodiment and the third embodiment.

The first embodiment is explained by taking the hybrid hydraulic excavator <NUM> of a crawler type as a construction.

The third embodiment is explained by taking the electric hydraulic excavator of a crawler type as a construction machine,.

Further, each of the embodiments is described as an example, and partial replacement and combination of the components shown in the different embodiments are made possible without mentioning.

Claim 1:
A hydraulic excavator comprising:
an electric motor (<NUM>);
a hydraulic pump (<NUM>) driven by the electric motor (<NUM>);
a hydraulic device (2A, 3A, 8D, 8E, 8F) driven by pressurized oil delivered from the hydraulic pump (<NUM>);
an electricity storage device (<NUM>) that supplies power to the electric motor (<NUM>);
an inverter (<NUM>) provided between the electricity storage device (<NUM>) and the electric motor (<NUM>) to convert the power;
a main controller (<NUM>) that controls the hydraulic pump (<NUM>) and the hydraulic device (2A, 3A, 8D, 8E, 8F);
an electricity storage device controller (<NUM>, <NUM>) that controls the electricity storage device (<NUM>);
an equipment controller (<NUM>, <NUM>, <NUM>) that controls the electric motor (<NUM>), the inverter (<NUM>) and the electricity storage device controller (<NUM>, <NUM>); and
a relay (<NUM>, <NUM>, <NUM>) connecting or disconnecting an electrical circuit to which the inverter (<NUM>) and the electricity storage device (<NUM>) are connected,
characterized in that:
the equipment controller (<NUM>, <NUM>, <NUM>) and the electricity storage device controller (<NUM>, <NUM>) each include an excitation current control section (<NUM>, <NUM>, 42A, 43A) that controls supply and stop of an excitation current in the relay (<NUM>),
when a state of the electricity storage device (<NUM>) is determined to be an abnormal state requiring the stop of the excitation current in the relay (<NUM>), the electricity storage device controller (<NUM>, <NUM>) transmits an abnormal signal to the equipment controller (<NUM>, <NUM>, <NUM>), and
the equipment controller (<NUM>, <NUM>, <NUM>) executes stop processing of the electric motor (<NUM>) and the inverter (<NUM>) based upon the abnormal signal from the electricity storage device controller (<NUM>, <NUM>), then stops the excitation current in the relay (<NUM>) by the excitation current control section (<NUM>, 42A) of the equipment controller (<NUM>, <NUM>, <NUM>), and transmits a signal of a state of the relay (<NUM>) to the electricity storage device controller (<NUM>, <NUM>).