Patent Description:
A control system is known which includes a controller, a sensor, or the like that has a self-diagnosing function of diagnosing the presence or absence of an own abnormality when power is turned on. Patent Document <NUM> discloses a control system for a vehicle, the control system including a sensor having a self-diagnosing function and a power interrupting unit that can interrupt supply of power to the sensor. In the control system described in Patent Document <NUM>, the power supply to the sensor is interrupted when a brake operation is performed and the vehicle is set in a stopped state, and the self-diagnosis of the sensor is performed by performing the power supply to the sensor afterward.

A work machine such as a hydraulic excavator or the like performs work such as excavation or the like by a work device when a machine body is in a stopped state in which travelling operation is stopped. Therefore, when power supply to the controller having a self-diagnosing function is interrupted while the machine body is in the stopped state in which travelling operation is stopped, work using the work device may be hindered, and work efficiency may be decreased.

It is an object of the present invention to provide a work machine in which self-diagnosis of a controller can be performed at an appropriate frequency without decreasing efficiency of work using a work device.

A work machine according to one aspect of the present invention includes: a work device; an operation device operating the work device; a first controller configured to control operation of the work device on the basis of operation of the operation device; and a second controller configured to determine that an auto idle condition is satisfied and perform auto idle control that decreases an engine revolution speed to an idle revolution speed in case the operation device is not operated for a predetermined time. The first controller is configured to diagnose presence or absence of a failure in the first controller when supply of power to the first controller is started. The second controller is configured to perform power interruption control that interrupts the supply of the power to the first controller in case the auto idle condition is satisfied, and perform power supply control that starts the supply of the power to the first controller afterward.

According to the present invention, it is possible to provide a work machine in which self-diagnosis of a first controller can be performed at an appropriate frequency without decreasing efficiency of work using a work device.

Work machines according to embodiments of the present invention will be described with reference to the drawings.

<FIG> is a side view showing a configuration of a hydraulic excavator <NUM> as an example of a work machine. In the hydraulic excavator <NUM>, various kinds of actuators are driven by a hydraulic operating fluid delivered from a hydraulic pump (not shown) to perform various work.

As shown in <FIG>, the hydraulic excavator <NUM> includes a track structure <NUM>, a swing structure <NUM> swingably provided on the track structure <NUM>, and a front work device <NUM> provided to the swing structure <NUM>. The track structure <NUM> travels with a pair of left and right crawlers driven by a travelling motor. The swing structure <NUM> is swung by a swing motor <NUM>.

A cab <NUM> is provided on the left side of a front portion of the swing structure <NUM>. An engine compartment is provided to a rear portion of the cab <NUM>. Provided within the cab <NUM> are a cab seat on which an operator is seated and an operation lever <NUM> as an operation device for operating the front work device <NUM>. The operation lever <NUM> is provided with an operation sensor 23a (see <FIG>) such as a potentiometer or the like that detects an operation (an operation direction and an operation amount) of the operation lever <NUM>. In addition, an engine control dial 20a (see <FIG>) for setting an engine revolution speed (revolution speed per minute) is provided within the cab <NUM>. The engine control dial 20a is an operation device that sets a target value (command value) of the revolution speed of an engine <NUM>. The engine control dial 20a is operated by the operator of the hydraulic excavator <NUM>.

The engine compartment houses the engine <NUM> as a power source, a battery <NUM> that supplies power to a machine body, hydraulic apparatuses, and the like. As the hydraulic apparatuses, there are hydraulic pumps (a main pump and a pilot pump) driven by the engine <NUM>, a control valve that controls a flow of hydraulic operating fluid delivered from the hydraulic pumps, a proportional valve unit <NUM> that outputs a pilot pressure to a pressure receiving chamber of the control valve (see <FIG>), and the like. A counterweight for balancing the machine body during work is attached to a rear portion of the engine compartment.

The front work device <NUM> is provided to the right side of a front portion of the swing structure <NUM>. The front work device <NUM> includes a plurality of front implement members, that is, a boom <NUM>, an arm <NUM>, and a bucket <NUM>. A proximal end of the boom <NUM> is rotatably attached to a front portion of the swing structure <NUM>. A proximal end of the arm <NUM> is rotatably attached to a distal end of the boom <NUM>. The boom <NUM> and the arm <NUM> rise and fall by being driven by a boom cylinder <NUM> and an arm cylinder <NUM>, respectively. The bucket <NUM> is attached to a distal end of the arm <NUM> so as to be vertically rotatable with respect to the arm <NUM>. The bucket <NUM> is driven by a bucket cylinder <NUM>.

<FIG> is a functional block diagram of assistance in explaining a configuration of a control system <NUM> of the hydraulic excavator <NUM>. The control system <NUM> of the hydraulic excavator <NUM> includes a plurality of controllers <NUM>, <NUM>, and <NUM> and the battery <NUM> that supplies power to each of the controllers <NUM>, <NUM>, and <NUM>. Each of the controllers <NUM>, <NUM>, and <NUM> is constituted by a microcomputer including a CPU (Central Processing Unit) as an operation circuit and a ROM (Read Only Memory) and a RAM (Random Access Memory) as a storage device as well as an input-output interface (I/O interface) and other peripheral circuits. The controllers <NUM>, <NUM>, and <NUM> control various parts of the hydraulic excavator <NUM>. The storage devices of the controllers <NUM>, <NUM>, and <NUM> store a program capable of performing various kinds of calculations. That is, the storage devices of the controllers <NUM>, <NUM>, and <NUM> are storage media from which programs implementing functions of the present embodiment are readable.

The main controller <NUM> controls operation of each hydraulic cylinder (<NUM>, <NUM>, <NUM>) of the front work device <NUM> or the like on the basis of operation of the operation lever <NUM>. The engine controller <NUM> sets a target engine revolution speed on the basis of a command value of the engine control dial 20a or the like, and controls the engine <NUM> such that an actual revolution speed of the engine <NUM> becomes the set target engine revolution speed. The sub-controller <NUM> outputs an auto idle activating command for performing auto idle control that controls the engine revolution speed to an idle revolution speed to the engine controller <NUM> when an auto idle condition to be described later is satisfied. When the auto idle activating command is input to the engine controller <NUM>, the engine controller <NUM> sets the idle revolution speed as the target engine revolution speed, and controls the engine <NUM> such that the actual revolution speed of the engine <NUM> becomes the idle revolution speed.

The proportional valve unit <NUM> is connected to the main controller <NUM>. The proportional valve unit <NUM> includes a plurality of solenoid proportional valves capable of adjusting the opening degree of a valve according to an operation command (control current) from the main controller <NUM>. The main controller <NUM> outputs, to the solenoid of a solenoid proportional valve corresponding to an operated operation lever <NUM> and the operation direction of the operation lever <NUM>, an operation command (control current) corresponding to the operation angle (operation amount) of the operation lever <NUM>.

Each solenoid proportional valve provided in the proportional valve unit <NUM> reduces the delivery pressure of a pilot pump (not shown) driven by the engine <NUM>, and outputs the reduced pressure as a pilot pressure to the pressure receiving chamber of the control valve. The control valve is provided between a main pump (not shown) driven by the engine <NUM> and each hydraulic cylinder (<NUM>, <NUM>, <NUM>), and controls a flow of hydraulic operating fluid supplied from the main pump to each hydraulic cylinder (<NUM>, <NUM>, <NUM>). A spool of the control valve operates when the pilot pressure corresponding to the operation amount of the operation lever <NUM> is output from the proportional valve unit <NUM> and the pilot pressure acts on the pressure receiving chamber of the control valve. Consequently, the hydraulic operating fluid is introduced from the main pump into a bottom chamber or a rod chamber of the hydraulic cylinder (<NUM>, <NUM>, <NUM>), and the hydraulic cylinder expands or contracts. Hence, the hydraulic cylinder (<NUM>, <NUM>, <NUM>) performs operation (expansion/contraction) corresponding to the operation direction of the operation lever <NUM> at a speed corresponding to the operation angle (operation amount).

As shown in <FIG>, the operation sensor 23a of the operation lever <NUM> is connected to the main controller <NUM>, and an operation signal detected by the operation sensor 23a is input to the main controller <NUM>. The main controller <NUM> includes: an operation signal detecting section <NUM> that detects the operation signal (voltage value) indicating the operation direction and operation amount of the operation lever <NUM>; an operation command value calculating section <NUM> that calculates a current value (operation command value) of a control current to be output to the proportional valve unit <NUM> on the basis of the operation signal of the operation lever <NUM>, which is detected by the operation signal detecting section <NUM>; an operation command output section <NUM> that outputs the control current (operation command) having the current value (operation command value) calculated by the operation command value calculating section <NUM> to the proportional valve unit <NUM>; and a self-diagnosing section <NUM> that diagnoses the presence or absence of an own failure (abnormality). Details of the self-diagnosing section <NUM> will be described later.

<FIG> is a diagram showing a conversion table used when the operation command value calculating section <NUM> calculates the current value (operation command value). The storage device of the main controller <NUM> stores the conversion table shown in <FIG> in the form of a look-up table. The conversion table is a table in which the current value (axis of ordinates) is set according to the voltage value (axis of abscissas).

The operation signal detecting section <NUM> detects a voltage value of <NUM> [V] to <NUM> [V] as the operation signal indicating the operation direction and the operation amount from the operation sensor 23a of the operation lever <NUM>. The operation command value calculating section <NUM> refers to the conversion table shown in <FIG>, and calculates the current value corresponding to the voltage value detected by the operation signal detecting section <NUM>.

In the present embodiment, the operation sensor 23a outputs a voltage of <NUM> [V] when the operation lever <NUM> is in a neutral position. The operation sensor 23a outputs a voltage equal to or higher than V1 and lower than V2 (<NUM> < V1 < <NUM> and <NUM> < V2 < <NUM>) when the operation lever <NUM> is in a dead band. As the voltage value output from the operation sensor 23a, when the operation lever <NUM> is operated to one side beyond the dead band, the output voltage value increases according to an increase in the operation amount. When the operation lever <NUM> is operated to a maximum operation position on the one side (when the operation lever <NUM> is operated fully), the operation sensor 23a outputs a voltage of <NUM> [V]. In addition, as the voltage value output from the operation sensor 23a, when the operation lever <NUM> is operated to another side beyond the dead band, the output voltage value decreases according to an increase in the operation amount. When the operation lever <NUM> is operated to a maximum operation position on the other side (when the operation lever <NUM> is operated fully), the operation sensor 23a outputs a voltage of <NUM> [V].

When the operation lever <NUM> is in the dead band, the operation command output section <NUM> outputs a standby current (a current value of I0 [mA]). When the operation lever <NUM> is operated to the one side beyond the dead band, the current value (operation command value) of the control current output by the operation command output section <NUM> increases according to an increase in the operation amount (increase in the voltage value). Similarly, when the operation lever <NUM> is operated to the other side beyond the dead band, the current value (operation command value) of the control current output by the operation command output section <NUM> increases according to an increase in the operation amount (decrease in the voltage value).

When the control current (exciting current) output from the operation command output section <NUM> is input to the solenoid of the solenoid proportional valve of the proportional valve unit <NUM>, the opening degree of the valve is controlled according to the current value of the control current. The larger the current value of the control current, the larger the opening degree of the solenoid proportional valve. When the solenoid proportional valve is opened, a pilot pressure is introduced into the pressure receiving chamber of the control valve, the opening degree of the control valve is adjusted according to the pilot pressure, and thus the pressure of the hydraulic operating fluid actuating the hydraulic actuator (for example the boom cylinder <NUM>) is adjusted.

As shown in <FIG>, the operation sensor 23a of the operation lever <NUM> is connected to the sub-controller <NUM>, and an operation signal from the operation sensor 23a is input to the sub-controller <NUM>. The sub-controller <NUM> includes an operation determining section <NUM>, a first time measuring section <NUM>, an auto idle determining section <NUM>, and a relay control section <NUM>. Details of the relay control section <NUM> will be described later.

The operation determining section <NUM> determines whether or not the operation lever <NUM> is operated. The operation determining section <NUM> determines that the operation lever <NUM> is not operated when a signal indicating that the operation lever <NUM> is in the dead band (the voltage value shown in <FIG> is equal to or higher than V1 and lower than V2) is input. The operation determining section <NUM> determines that the operation lever <NUM> is operated when a signal indicating that the operation lever <NUM> is operated beyond the dead band (the voltage value shown in <FIG> is lower than V1 or equal to or higher than V2) is input.

The first time measuring section <NUM> measures time by a first timer (not shown) included in the sub-controller <NUM> when the operation determining section <NUM> determines that the operation lever <NUM> is not operated. The first time measuring section <NUM> resets the first timer and sets a measured time T1 to <NUM> (zero) when the operation determining section <NUM> determines that the operation lever <NUM> is operated. That is, the first time measuring section <NUM> measures the time (non-operation time) T1 for which the operation lever <NUM> is continuously not operated.

The auto idle determining section <NUM> determines whether or not the auto idle condition is satisfied on the basis of a result of determination of the operation determining section <NUM> and a result of measurement in the first time measuring section <NUM>. Specifically, when it is determined that the front work device <NUM> is operated, the auto idle determining section <NUM> determines that the auto idle condition is not satisfied, and outputs an auto idle clearing command. In addition, the auto idle determining section <NUM> determines whether or not the time T1 measured by the first time measuring section <NUM> has passed a predetermined time Tt1. When the time T1 measured by the first time measuring section <NUM> is less than the predetermined time Tt1, the auto idle determining section <NUM> determines that the auto idle condition is not satisfied, and outputs the auto idle clearing command. When the time T1 measured by the first time measuring section <NUM> is equal to or more than the predetermined time Tt1, the auto idle determining section <NUM> determines that the auto idle condition is satisfied, and outputs the auto idle activating command. The predetermined time Tt1 is a threshold value for determining that the auto idle condition is satisfied. The predetermined time Tt1 can be set optionally. The predetermined time Tt1 is stored in the storage device of the sub-controller <NUM> in advance.

The engine controller <NUM> includes a determination result receiving section <NUM>, an auto idle command section <NUM>, and an engine revolution speed adjusting section <NUM>. A signal indicating a result of determination by the auto idle determining section <NUM> (auto idle activating command/auto idle clearing command) is input to the determination result receiving section <NUM>. The auto idle command section <NUM> sets the target revolution speed of the engine <NUM> to an auto idle revolution speed, and outputs a signal indicating the target revolution speed (auto idle revolution speed) to the engine revolution speed adjusting section <NUM> when the auto idle activating command is input to the determination result receiving section <NUM>. The engine revolution speed adjusting section <NUM> outputs, to the engine <NUM>, a revolution speed command signal for making the actual revolution speed of the engine <NUM> the target revolution speed (auto idle revolution speed).

The auto idle command section <NUM> does not output the signal indicating the value of the target revolution speed (auto idle revolution speed) to the engine revolution speed adjusting section <NUM> when the auto idle clearing command is input to the determination result receiving section <NUM>. In this case, the engine revolution speed adjusting section <NUM> outputs a predetermined revolution speed command signal corresponding to a normal operation state to the engine <NUM> on the basis of the target revolution speed set by the engine control dial 20a or the like.

Thus, in the present embodiment, the main controller <NUM> functions as a first controller that controls the operation of the front work device <NUM> on the basis of an operation of the operation lever <NUM>. In addition, the sub-controller <NUM> and the engine controller <NUM> function as a second controller that performs auto idle control that, in case the operation lever <NUM> is not operated for the predetermined time Tt1, determines that the auto idle condition is satisfied, and decreases the engine revolution speed to the idle revolution speed lower than the target revolution speed set by the engine control dial 20a.

The battery <NUM> is connected to power supply circuits (not shown) of the main controller <NUM>, the sub-controller <NUM>, and the engine controller <NUM>. A lead storage battery, which is common as an electrical storage device that stores charge, for example, is used as the battery <NUM>. When the operator turns on an ignition switch, power is supplied from the battery <NUM> to each of the controllers <NUM>, <NUM>, and <NUM>.

Description will next be made of a self-diagnosing function possessed by the main controller <NUM> and control based on a diagnosis result of the self-diagnosing function. The main controller <NUM> has the self-diagnosing function of diagnosing the presence or absence of a failure in itself (the main controller <NUM>) when the supply of power to itself (the main controller <NUM>) is started.

When the operator turns on the ignition switch, and thereby turns on power, the self-diagnosing section <NUM> of the main controller <NUM> performs failure diagnosis (abnormality diagnosis) on electronic apparatuses (not shown) such as the CPU of the main controller <NUM> and various kinds of I/Os. When the self-diagnosis detects a failure (abnormality), the self-diagnosing section <NUM> outputs, to the operation command output section <NUM>, a command to inhibit the output of the operation command (control current) to the proportional valve unit <NUM>. Hence, in this case, the front work device <NUM> does not operate even when the operation lever <NUM> is operated beyond the dead band.

When the self-diagnosis does not detect any failure, the self-diagnosing section <NUM> does not output, to the operation command output section <NUM>, the command to inhibit the output of the operation command (control current) to the proportional valve unit <NUM>. That is, the self-diagnosing section <NUM> permits the output of the operation command (control current) from the operation command output section <NUM> to the proportional valve unit <NUM>. Hence, in this case, as described above, the operation command output section <NUM> outputs the operation command (control current) corresponding to the operation command value (control current value) calculated by the operation command value calculating section <NUM> to the proportional valve unit <NUM> on the basis of the operation signal of the operation lever <NUM>, which is detected by the operation signal detecting section <NUM>. Therefore, the front work device <NUM> operates according to the operation of the operation lever <NUM>.

Here, the following problems occur when the supply of power to the main controller <NUM> is interrupted on condition only that the track structure <NUM> is in a stop state, and thereafter the failure self-diagnosis of the main controller <NUM> is performed by supplying power to the main controller <NUM>. The work machine such as the hydraulic excavator <NUM> performs work such as excavation or the like by a work device such as the front work device <NUM> in a state in which the track structure <NUM> is stopped. Hence, in the work machine, if the supply of power to the main controller <NUM> is interrupted when the state in which the track structure <NUM> is stopped is detected, work using the front work device <NUM> may be hindered, and work efficiency may be decreased. For example, in the hydraulic excavator <NUM> according to the present embodiment, if the supply of power to the main controller <NUM> is interrupted when the state in which the track structure <NUM> is stopped is detected, the main controller <NUM> cannot detect the operation signal of the operation lever <NUM>, nor can output the operation command to the proportional valve unit <NUM>. That is, a quick transition to work using the front work device <NUM> cannot be made after the track structure <NUM> is stopped.

Accordingly, in the present embodiment, in a state in which there is no intention of work using the front work device <NUM>, that is, when the auto idle condition is satisfied, the power supplied to the main controller <NUM> is interrupted, and the self-diagnosis is performed afterward by supplying the power to the main controller <NUM>. Details will be described in the following.

The hydraulic excavator <NUM> according to the present embodiment has a relay <NUM> provided to a power line that connects the battery <NUM> and the power supply circuit of the main controller <NUM> to each other. The relay <NUM> functions as a power interrupting unit capable of interrupting the supply of power from the battery <NUM> to the main controller <NUM> on the basis of a command from the sub-controller <NUM>. When a conduction signal is input from the sub-controller <NUM> to the relay <NUM>, the relay <NUM> is set in a conduction state (closed state), and permits the supply of power from the battery <NUM> to the main controller <NUM>. When an interruption signal is input from the sub-controller <NUM> to the relay <NUM>, the relay <NUM> is set in an interrupting state (opened state), and interrupts the supply of power from the battery <NUM> to the main controller <NUM>.

The relay control section <NUM> of the sub-controller <NUM> controls the conduction/interruption of the relay <NUM> on the basis of a result of determination by the auto idle determining section <NUM>. The relay control section <NUM> outputs the conduction signal for setting the relay <NUM> in the conduction state to the relay <NUM> when the auto idle determining section <NUM> determines that the auto idle condition is not satisfied. The relay control section <NUM> outputs the interruption signal for setting the relay <NUM> in the interrupting state to the relay <NUM> when the auto idle determining section <NUM> determines that the auto idle condition is satisfied.

In addition, the relay control section <NUM> has a function as a second time measuring section that starts measuring time by a second timer (not shown) included in the sub-controller <NUM> when the auto idle determining section <NUM> determines that the auto idle condition is satisfied. The relay control section (second time measuring section) <NUM> resets the second timer and sets a measured time T2 to <NUM> (zero) when the auto idle determining section <NUM> determines that the auto idle condition is not satisfied. That is, the relay control section (second time measuring section) <NUM> measures a time for which the interruption signal is continuously output (power interruption time).

The relay control section <NUM> further determines whether or not the measured time T2 has passed a predetermined time Tt2. The relay control section <NUM> outputs the interruption signal for setting the relay <NUM> in the interrupting state to the relay <NUM> when the measured time T2 is less than the predetermined time Tt2. The relay control section <NUM> outputs the conduction signal for setting the relay <NUM> in the conduction state to the relay <NUM> when the measured time T2 is equal to or more than the predetermined time Tt2. The predetermined time Tt2 is a time for which the supply of power to the main controller <NUM> is interrupted (for example, about <NUM>). The predetermined time Tt2 can be set optionally. The predetermined time Tt2 is stored in the storage device of the sub-controller <NUM> in advance.

Thus, the sub-controller <NUM> performs power interruption control that interrupts the supply of power from the battery <NUM> to the main controller <NUM> when the auto idle condition is satisfied, and performs power supply control that starts the supply of power from the battery <NUM> to the main controller <NUM> afterward.

<FIG> is a flowchart illustrating an example of processing contents of auto idle determination control by the sub-controller <NUM> in the hydraulic excavator <NUM> according to the first embodiment. The processing shown in this flowchart is, for example, started by turning on the ignition switch not shown, and is repeatedly performed in a predetermined control cycle after an initial setting not shown is made.

In step S110, the sub-controller <NUM> determines whether or not an operation for operating front implement members (the boom <NUM>, the arm <NUM>, and the bucket <NUM>) of the front work device <NUM> is performed on the basis of a result detected by the operation sensor 23a. Operations for operating the front implement members of the front work device <NUM> are boom raising, boom lowering, arm crowding, arm dumping, bucket crowding, and bucket dumping operations.

In step S110, when all of operation levers <NUM> of the front implement members constituting the front work device <NUM> are in the dead band, the sub-controller <NUM> determines that no operation for operating the front work device <NUM> is performed. The sub-controller <NUM> then proceeds to step S123. In step S110, when one of the operation levers <NUM> of the front implement members constituting the front work device <NUM> is operated beyond the dead band, the sub-controller <NUM> determines that an operation for operating the front work device <NUM> is performed. The sub-controller <NUM> then proceeds to step S135.

In step S123, the sub-controller <NUM> performs processing of measuring time by the first timer, that is, timer count-up processing of adding a time Δt corresponding to the control cycle to the measured time T1 (T1 = T1 + ΔT). The sub-controller <NUM> then proceeds to S125.

In step S125, the sub-controller <NUM> determines whether or not the time T1 measured by the first timer is equal to or more than the predetermined time Tt1. When the measured time T1 is less than the predetermined time Tt1 in step S125, the processing proceeds to step S127. In step S127, the sub-controller <NUM> determines that the auto idle condition is not satisfied, and outputs the auto idle clearing command. The sub-controller <NUM> then returns to step S110. When the measured time T1 is equal to or more than the predetermined time Tt1 in step S125, the processing proceeds to step S130.

In step S130, the sub-controller <NUM> determines that the auto idle condition is satisfied, and outputs the auto idle activating command. The sub-controller <NUM> then ends the processing shown in the flowchart of <FIG>. Incidentally, when the auto idle condition is satisfied, and the auto idle activating command is output, the engine controller <NUM> performs auto idle control that adjusts the engine revolution speed to a predetermined idle revolution speed.

When it is determined in step S110 that there is an operation of the front implement members, the processing proceeds to step S135. In step S135, the sub-controller <NUM> determines that the auto idle condition is not satisfied, and outputs the auto idle clearing command and resets the first timer (T1 = <NUM>). The sub-controller <NUM> then ends the processing shown in the flowchart of <FIG>.

<FIG> is a flowchart illustrating an example of processing contents of control of the relay by the sub-controller <NUM> in the hydraulic excavator <NUM> according to the first embodiment. The processing shown in this flowchart is, for example, started by turning on the ignition switch not shown, and is repeatedly performed in a predetermined control cycle after an initial setting not shown is made.

In step S160, the sub-controller <NUM> determines whether or not the auto idle activating command is output. When it is determined in step S160 that the auto idle activating command is output, the processing proceeds to step S173. When it is determined in step S160 that the auto idle activating command is not output, the processing proceeds to step S190.

In step S173, the sub-controller <NUM> performs processing of measuring time by the second timer, that is, timer count-up processing of adding a time Δt corresponding to the control cycle to the measured time T2 (T2 = T2 + Δt). The sub-controller <NUM> then proceeds to step S175.

In step S175, the sub-controller <NUM> determines whether or not the time T2 measured by the second timer is less than the predetermined time Tt2. When the measured time T2 is less than the predetermined time Tt2 in step S175, the processing proceeds to step S180. In step S180, the sub-controller <NUM> outputs a relay interrupting command. The sub-controller <NUM> then returns to step S160.

When the measured time T2 is equal to or more than the predetermined time Tt2 in step S175, the processing proceeds to step S185. In step S185, the sub-controller <NUM> outputs a relay connecting command. The sub-controller <NUM> then ends the processing shown in the flowchart of <FIG>. Incidentally, when it is determined in step S160 that the auto idle activating command is not output, the processing proceeds to step S190. In step S190, the sub-controller <NUM> outputs the relay connecting command, and resets the second timer (T2 = <NUM>). The sub-controller <NUM> then ends the processing shown in the flowchart of <FIG>.

As described above, in the present embodiment, when the auto idle condition is satisfied, the auto idle activating command is output from the sub-controller <NUM>, the engine controller <NUM> performs the auto idle control, and the relay interrupting command is output from the sub-controller <NUM> and the relay <NUM> is thereby set in the interrupting state until the predetermined time Tt2 passes after the auto idle activating command is output. Thus, the supply of power from the battery <NUM> to the main controller <NUM> is interrupted, so that all of the functions of the main controller <NUM> are stopped.

Then, when the predetermined time Tt2 passes after the auto idle activating command is output, the relay connecting command is output from the sub-controller <NUM>, and the relay <NUM> is thereby set in a connecting state. Consequently, power is supplied from the battery <NUM> to the main controller <NUM>. Therefore, the main controller <NUM> performs self-diagnosis, and thereafter makes a transition to a normal control state.

A period from activation of the engine <NUM> by the ignition switch to stopping of the engine <NUM> (that is, a period from power-on to power-off) in the work machine such as the hydraulic excavator <NUM> is longer than that of a vehicle intended to transport humans and freight, such as an automobile. With the work machine, there are often situations in which, for example, operators are changed while the engine <NUM> is kept running, and work is resumed, or a break is taken while the engine <NUM> is kept running in order to maintain air conditioning or the temperature of the hydraulic operating fluid and work is resumed directly on a site in a harsh environment such as a cold region. In addition, in a case in which an unmanned operation technology is applied to the work machine, a situation is expected in which work is continued for hours until a fuel is replenished.

Hence, there is a problem of fewer opportunities for self-diagnosis when the work machine is configured to perform the self-diagnosing function of the main controller <NUM> only at a time of turning on power. According to the present embodiment, when operators are changed while the engine <NUM> is kept running and when an operator takes a break while the engine <NUM> is kept running, the auto idle condition is satisfied, and therefore opportunities for self-diagnosis of the main controller <NUM> can be increased. In addition, the auto idle condition is not satisfied when work using the front work device <NUM> is performed in a state in which the track structure <NUM> is stopped. That is, the main controller <NUM> is not restarted at a time of a stop of the track structure <NUM>, and therefore the work of the front work device <NUM> is not hindered. That is, according to the present embodiment, it is possible to provide the hydraulic excavator <NUM> in which self-diagnosis of the main controller <NUM> can be performed at an appropriate frequency without decreasing efficiency of work using the front work device <NUM>.

The foregoing first embodiment has the following actions and effects.

According to such a present embodiment, it is possible to provide the hydraulic excavator <NUM> in which self-diagnosis of the main controller <NUM> can be performed at an appropriate frequency without decreasing the efficiency of work using the front work device <NUM>. As a result, reliability of the hydraulic excavator <NUM> can be maintained for a long period.

A control system <NUM> of a hydraulic excavator <NUM> according to a second embodiment will be described with reference to <FIG> and <FIG>. Incidentally, in the figures, parts identical to or corresponding to those of the first embodiment are identified by the same reference numerals, and differences will be mainly described. <FIG> is a diagram similar to <FIG>, and is a functional block diagram of assistance in explaining a configuration of the control system <NUM> of the hydraulic excavator <NUM> according to the second embodiment.

As shown in <FIG>, the hydraulic excavator <NUM> according to the second embodiment has a configuration similar to that of the first embodiment, and further includes a shutoff lever (referred to also as a gate lock lever) <NUM>. The shutoff lever <NUM> is provided within the cab <NUM> of the hydraulic excavator <NUM>. The shutoff lever <NUM> is selectively operable to a lowered position that limits an entrance to the cab <NUM> (lock release position) and a raised position that opens the entrance to the cab <NUM> (lock position).

When the shutoff lever <NUM> is operated to the lock position (raised position), a locked state is set in which a hydraulic circuit between the proportional valve unit <NUM> and the pilot pump is interrupted, and the driving of each hydraulic actuator of the front work device <NUM> is prohibited. Hence, during the locked state, the hydraulic actuator is not actuated even when the operation lever <NUM> is operated. When the shutoff lever <NUM> is operated to the lock release position (lowered position), an unlocked state is set in which the interruption of the hydraulic circuit between the proportional valve unit <NUM> and the pilot pump is cleared, and the driving of each actuator of the front work device <NUM> is permitted. Hence, during the unlocked state, the hydraulic actuator is actuated on the basis of an operation of the operation lever <NUM>. That is, the shutoff lever <NUM> functions as a lock operation device selectively operated to the lock release position in which operation of the operation lever <NUM> is enabled and the lock position in which operation of the operation lever <NUM> is disabled. The shutoff lever <NUM> is provided with an operation position sensor 260a that detects the operation position (lock position/lock release position) of the shutoff lever <NUM>, and outputs a detection signal to the sub-controller <NUM>.

The sub-controller <NUM> includes a locked state determining section <NUM> that determines whether or not the hydraulic excavator <NUM> is in the locked state on the basis of the detection signal from the operation position sensor 260a. In other words, the locked state determining section <NUM> is an operation position determining section that detects whether or not the shutoff lever <NUM> is operated to the lock position. When a signal indicating that the shutoff lever <NUM> is operated to the lock position is input from the operation position sensor 260a to the sub-controller <NUM>, the locked state determining section <NUM> determines that the hydraulic excavator <NUM> is in the locked state. When a signal indicating that the shutoff lever <NUM> is operated to the lock release position is input from the operation position sensor 260a to the sub-controller <NUM>, the locked state determining section <NUM> determines that the hydraulic excavator <NUM> is not in the locked state, that is, is in the unlocked state.

A relay control section <NUM> has the following function in addition to the functions of the above-described relay control section <NUM>. The relay control section <NUM> does not perform the above-described power interruption control when the locked state determining section <NUM> determines that the hydraulic excavator <NUM> is in the unlocked state, that is, when the shutoff lever <NUM> is operated to the lock release position, even when the auto idle condition is satisfied and the auto idle activating command is output.

<FIG> is a flowchart illustrating an example of processing contents of relay control by a sub-controller <NUM> in the hydraulic excavator <NUM> according to the second embodiment. In <FIG>, the processing of step S263 is added between the processing of step S160 and the processing of step S173 in the flowchart of <FIG>. Incidentally, in <FIG>, the same processing as the processing of <FIG> is identified by the same reference numerals, and parts different from the processing of <FIG> will be mainly described. The processing shown in this flowchart is started by turning on the ignition switch not shown, and is repeatedly performed in a predetermined control cycle after an initial setting not shown is made.

When it is determined in step S160 that the auto idle activating command is output, the processing proceeds to step S263. In step S263, the sub-controller <NUM> determines whether or not the hydraulic excavator <NUM> is in the locked state. When it is determined that the hydraulic excavator <NUM> is in the locked state, the processing proceeds to step S173. When it is determined that the hydraulic excavator <NUM> is not in the locked state (that is, the hydraulic excavator <NUM> is in the unlocked state), the processing proceeds to step S190.

Hence, in the present second embodiment, when the auto idle condition is satisfied and the hydraulic excavator <NUM> is in the locked state, the relay interrupting command is output from the sub-controller <NUM> and thus the relay <NUM> is set in the interrupting state until the predetermined time Tt2 passes. Consequently, the supply of power from the battery <NUM> to the main controller <NUM> is interrupted, so that all of the functions of the main controller <NUM> are stopped.

Then, when the predetermined time Tt2 passes, the relay connecting command is output from the sub-controller <NUM>, and thus the relay <NUM> is set in the connecting state. Consequently, power is supplied from the battery <NUM> to the main controller <NUM>. Therefore, the main controller <NUM> performs self-diagnosis, and thereafter makes a transition to a normal control state.

Such a second embodiment has the following actions and effects in addition to actions and effects similar to those of the foregoing first embodiment.

(<NUM>) The hydraulic excavator <NUM> further includes the shutoff lever (lock operation device) <NUM> that is selectively operated to the lock release position in which operation of the operation lever (operation device) <NUM> is enabled and the lock position in which operation of the operation lever (operation device) <NUM> is disabled. The sub-controller (second controller) <NUM> does not perform the power interruption control in case the shutoff lever (lock operation device) <NUM> is operated to the lock release position, even when the auto idle condition is satisfied.

According to such a configuration, the main controller <NUM> is restarted when the shutoff lever <NUM> is operated to the lock position (raised position) and the hydraulic excavator <NUM> is thereby set in the locked state, that is, when the operator explicitly sets a stopped state. It is therefore possible to prevent the main controller <NUM> from being restarted unintentionally in such a state that the operator temporarily discontinues operating the operation lever <NUM> although the operator does not have an intention of stopping.

Here, the following problems occur when a configuration is assumed in which the main controller <NUM> is restarted by temporarily discontinuing operating the operation lever <NUM> during the unlocked state. With this configuration, even when an operation of the operation lever <NUM> is performed immediately after interruption of power supply, the front work device <NUM> may not be able to be operated immediately because the main controller <NUM> is stopped or being started. That is, since the main controller <NUM> is restarted after an operation of the operation lever <NUM> is discontinued temporarily, work cannot be resumed immediately, and thus work efficiency may be degraded. On the other hand, the present second embodiment can prevent the main controller <NUM> from being restarted unintentionally when an operation of the operation lever <NUM> is temporarily discontinued. The present second embodiment can therefore improve work efficiency.

A control system <NUM> of a hydraulic excavator <NUM> according to a third embodiment will be described with reference to <FIG>. Incidentally, in the figures, parts identical to or corresponding to those of the first embodiment are identified by the same reference numerals, and differences will be mainly described. <FIG> is a diagram similar to <FIG>, and is a functional block diagram of assistance in explaining a configuration of the control system <NUM> of the hydraulic excavator <NUM> according to the third embodiment.

The hydraulic excavator <NUM> according to the third embodiment has a configuration similar to that of the first embodiment. In the third embodiment, a main controller <NUM> performs ending processing when the auto idle condition is satisfied, and a sub-controller <NUM> performs the power interruption control that interrupts the supply of power to the main controller <NUM> when the auto idle condition is satisfied and it is determined that the ending processing by the main controller <NUM> is completed. Details will be described in the following.

As shown in <FIG>, the main controller <NUM> includes an internal memory <NUM> as a storage device and an ending processing section <NUM> that performs the ending processing of storing various kinds of currently set setting values in the internal memory <NUM>. Incidentally, the various kinds of setting values include various setting values such as setting values set by the operator according to own preferences of the operator, for example, setting values for associating the operation levers <NUM> with the solenoid proportional valves of the proportional valve unit <NUM> (setting values for associating kinds of hydraulic actuators driven by the operation lever <NUM> on the right side of the cab seat and kinds of hydraulic actuators driven by the operation lever <NUM> on the left side of the cab seat), setting values for enabling/disabling various kinds of functions such as an assist function of assisting the operator in operation, and a setting value for correcting the current value obtained from the conversion table used for control of the proportional valve unit <NUM> or the like.

The ending processing section <NUM> performs the ending processing when the auto idle determining section <NUM> determines that the auto idle condition is satisfied and the auto idle activating command is input to the main controller <NUM>. Incidentally, the ending processing section <NUM> discontinues the ending processing and returns to a normal control state, when the operation lever <NUM> is operated and the auto idle clearing command is output from the auto idle determining section <NUM> during a period from a start of the ending processing by the main controller <NUM> to completion of the ending processing.

The sub-controller <NUM> includes a third time measuring section <NUM> that measures a time T3 after the auto idle condition is satisfied and an ending processing completion determining section <NUM> that determines whether or not the ending processing by the main controller <NUM> is completed on the basis of a result of determination in the auto idle determining section <NUM> and a result of measurement in the third time measuring section <NUM>.

The third time measuring section <NUM> starts measuring time by a third timer included in the sub-controller <NUM> when the auto idle activating command indicating a result of determining that the auto idle condition is satisfied is output from the auto idle determining section <NUM>. The third time measuring section <NUM> resets the third timer and sets the measured time T3 to <NUM> (zero) when the auto idle clearing command indicating a result of determining that the auto idle condition is not satisfied is output from the auto idle determining section <NUM>. That is, the third time measuring section <NUM> measures a time for which the auto idle condition continues to hold, that is, a time for which the auto idle activating command is continuously output.

The ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is not completed when the auto idle clearing command is output from the auto idle determining section <NUM>. In addition, the ending processing completion determining section <NUM> determines whether or not the time T3 measured by the third time measuring section <NUM> has passed a predetermined time Tt3. The ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is not completed when the time T3 measured by the third time measuring section <NUM> is less than the predetermined time Tt3. The ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is completed when the time T3 measured by the third time measuring section <NUM> is equal to or more than the predetermined time Tt3. The predetermined time Tt3 is a time obtained by adding a margin time to a time (for example <NUM> to <NUM>) taken from a start of the ending processing by the main controller <NUM> to completion of the ending processing. The predetermined time Tt3 is a threshold value set by experiment or the like. The predetermined time Tt3 is stored in the storage device of the sub-controller <NUM> in advance.

A relay control section <NUM> has the following functions in addition to the functions of the above-described relay control section <NUM>. The relay control section <NUM> outputs the interruption signal to the relay <NUM> when the ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is completed. The relay <NUM> is thereby set in the interrupting state. The relay control section <NUM> outputs a connection signal to the relay <NUM> after the passage of the predetermined time Tt2 from the output of the interruption signal. The relay <NUM> is thereby set in the connecting state. Incidentally, the relay control section <NUM> outputs the connection signal to the relay <NUM> when the ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is not completed.

<FIG> is a flowchart illustrating an example of processing contents of relay control by the sub-controller <NUM> in the hydraulic excavator <NUM> according to the third embodiment. In <FIG>, the processing of step S361 is performed in place of the processing of step S160 in the flowchart of <FIG>. Incidentally, in <FIG>, the same processing as the processing of <FIG> is identified by the same reference numerals, and parts different from the processing of <FIG> will be mainly described. The processing shown in this flowchart is started by turning on the ignition switch not shown, and is repeatedly performed in a predetermined control cycle after an initial setting not shown is made.

In step S361, the sub-controller <NUM> determines whether or not the ending processing by the main controller <NUM> is completed. When it is determined in step S361 that the ending processing is completed, the processing proceeds to step S173. When it is determined in step S361 that the ending processing is not completed, the processing proceeds to step S190.

Incidentally, whether or not the ending processing is completed is made according to the flowchart of ending processing completion determination processing shown in <FIG> is a flowchart illustrating an example of processing contents for determining whether or not the ending processing by the main controller <NUM> is completed. The ending processing completion determination processing by the sub-controller <NUM> will be described with reference to <FIG>. In step S340, the sub-controller <NUM> determines whether or not the auto idle activating command is output. When the sub-controller <NUM> determines in step S340 that the auto idle activating command is output, the sub-controller <NUM> proceeds to step S348. When the sub-controller <NUM> determines in step S340 that the auto idle activating command is not output, the sub-controller <NUM> proceeds to step S356.

In step S348, the sub-controller <NUM> performs processing of measuring time by the third timer, that is, timer count-up processing of adding a time Δt corresponding to the control cycle to the measured time T3 (T3 = T3 + ΔT). The sub-controller <NUM> then proceeds to step S349.

In step S349, the sub-controller <NUM> determines whether or not the time T3 measured by the third timer is equal to or more than the predetermined time Tt3. When the measured time T3 is less than the predetermined time Tt3 in step S349, the processing proceeds to step S351, where it is determined that the ending processing is not completed. The processing then returns to step S340.

When the measured time T3 is equal to or more than the predetermined time Tt3 in step S349, the processing proceeds to step S353, where it is determined that the ending processing is completed. The processing shown in the flowchart of <FIG> is then ended. Incidentally, when it is determined in step S340 that the auto idle activating command is not output, the processing proceeds to step S356. In step S356, the sub-controller <NUM> determines that the ending processing by the main controller <NUM> is not completed, and resets the third timer (T3 = <NUM>). The sub-controller <NUM> then ends the processing shown in the flowchart of <FIG>.

As described above, in the present third embodiment, when the auto idle condition is satisfied and the auto idle activating command is input to the main controller <NUM>, the main controller <NUM> performs the ending processing. The sub-controller <NUM> determines whether or not the ending processing by the main controller <NUM> is completed according to the processing of the flowchart of <FIG>, and controls the relay <NUM> according to the processing of the flowchart of <FIG> on the basis of a result of the determination.

Such a third embodiment has the following actions and effects in addition to actions and effects similar to those of the foregoing first embodiment.

(<NUM>) The main controller (first controller) <NUM> performs the ending processing when the auto idle condition is satisfied, and the sub-controller (second controller) <NUM> determines whether or not the ending processing by the main controller <NUM> (first controller) is completed, and performs the power interruption control in case the auto idle condition is satisfied and it is determined that the ending processing by the main controller (first controller) <NUM> is completed. Incidentally, in the present third embodiment, the sub-controller (second controller) <NUM> determines that the ending processing by the main controller (first controller) <NUM> is completed when the time T3 after the auto idle condition is satisfied has passed the predetermined time Tt3, and performs the power interruption control.

Thus, the main controller <NUM> can store various kinds of setting values in the internal memory <NUM> before the supply of power to the main controller <NUM> is interrupted. Therefore, the setting values can be prevented from being initialized after a restart due to the interruption of the power supply before completion of the ending processing in the main controller <NUM>. According to the present embodiment, the settings before the supply of power to the main controller <NUM> is interrupted can be taken over even after a restart. As a result, operation characteristics of the hydraulic excavator <NUM> according to operation of the operator can be prevented from changing between before and after a restart of the main controller <NUM>.

A control system <NUM> of a hydraulic excavator <NUM> according to a fourth embodiment will be described with reference to <FIG>. Incidentally, in the figures, parts identical to or corresponding to those of the third embodiment are identified by the same reference numerals, and differences will be mainly described. <FIG> is a diagram similar to <FIG>, and is a functional block diagram of assistance in explaining a configuration of the control system <NUM> of the hydraulic excavator <NUM> according to the fourth embodiment.

In the third embodiment, description has been made of an example in which the sub-controller <NUM> determines that the ending processing by the main controller <NUM> is completed when the time T3 from a start of output of the auto idle activating command (that is, a time after the auto idle condition is satisfied) has passed the predetermined time Tt3, and sets the relay <NUM> in the interrupting state. In the present fourth embodiment, on the other hand, a sub-controller <NUM> determines that the ending processing by a main controller <NUM> is completed when a signal indicating that the ending processing is completed is input from the main controller <NUM>, and sets the relay <NUM> in the interrupting state. Details will be described in the following.

An ending processing section <NUM> of the main controller <NUM> performs ending processing similar to that of the ending processing section <NUM> according to the foregoing third embodiment. In addition, the ending processing section <NUM> outputs a signal indicating that the ending processing is not completed (ending processing noncompletion notification) to the sub-controller <NUM> when the ending processing is not completed. The ending processing section <NUM> outputs a signal indicating that the ending processing is completed (ending processing completion notification) to the sub-controller <NUM> when the ending processing is completed. Incidentally, when the operation lever <NUM> is operated and the auto idle clearing command is output from the auto idle determining section <NUM> during a period from a start of the ending processing by the main controller <NUM> to completion of the ending processing, the ending processing section <NUM> discontinues the ending processing, returns to a normal control state, and outputs the ending processing noncompletion notification to the sub-controller <NUM>.

An ending processing completion determining section <NUM> of the sub-controller <NUM> determines whether or not the ending processing by the main controller <NUM> is completed on the basis of a signal (ending processing completion notification/ending processing noncompletion notification) from the main controller <NUM>. The ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is completed when a signal indicating that the ending processing is completed (ending processing completion notification) is input from the ending processing section <NUM> of the main controller <NUM>. The ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is not completed when a signal indicating that the ending processing is not completed (ending processing noncompletion notification) is input from the ending processing section <NUM>.

As in the foregoing third embodiment, the relay control section <NUM> outputs the interruption signal to the relay <NUM> when the ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is completed. The relay <NUM> is thereby set in the interrupting state. The relay control section <NUM> outputs the connection signal to the relay <NUM> after the predetermined time Tt2 has passed from the output of the interruption signal. The relay <NUM> is thereby set in the connecting state. Incidentally, the relay control section <NUM> outputs the connection signal to the relay <NUM> when the ending processing completion determining section <NUM> determines that the ending processing by the main controller <NUM> is not completed.

In the present fourth embodiment, the sub-controller <NUM> determines in step S361 shown in <FIG> that the ending processing by the main controller <NUM> is completed when the ending processing completion notification is output from the main controller <NUM>. The sub-controller <NUM> then proceeds to step S173. In step S361, the sub-controller <NUM> determines that the ending processing by the main controller <NUM> is not completed when the ending processing completion notification is not output from the main controller <NUM> (that is, when the ending processing noncompletion notification is output from the main controller <NUM>). The sub-controller <NUM> then proceeds to step S190.

As described above, in the present fourth embodiment, when the auto idle condition is satisfied and the auto idle activating command is input to the main controller <NUM>, the main controller <NUM> performs the ending processing. Then, when the ending processing is completed, the ending processing completion notification is output from the main controller <NUM> to the sub-controller <NUM>, and the relay <NUM> is controlled according to the processing of the flowchart of <FIG>.

Such a fourth embodiment has the following actions and effects in addition to actions and effects similar to those of the foregoing third embodiment.

(<NUM>) The sub-controller (second controller) <NUM>, when a signal indicating that the ending processing is completed (ending processing completion notification) is input from the main controller (first controller) <NUM>, determines that the ending processing by the main controller <NUM> is completed, and performs the power interruption control. Thus, the interruption of the supply of power to the main controller <NUM> before completion of the ending processing can be prevented more reliably. That is, the fourth embodiment can more effectively avoid a problem that appropriate setting values are not stored in the internal memory <NUM> and an unexpected operation occurs at a time of a restart.

The following modifications are also within the scope of the present invention. It is possible to combine a configuration illustrated in a modification and a configuration described in a foregoing embodiment with each other, combine configurations described in foregoing different embodiments with each other, or combine configurations described in following different modifications with each other.

Each of the controllers <NUM>, <NUM>, and <NUM> can be constituted by a plurality of microcomputers. In addition, instead of providing the sub-controller <NUM> and the engine controller <NUM> separately from each other, one controller having the functions of the sub-controller <NUM> and the engine controller <NUM> may be provided.

In the foregoing embodiments, description has been made of an example in which the front work device <NUM> is constituted by the boom <NUM>, the arm <NUM>, and the bucket <NUM>. However, the present invention is not limited to this. The structure, the number of joints, and the like of the work device can be configured arbitrarily. For example, a grapple that holds an object by being hydraulically opened and closed may be provided in place of the bucket <NUM>.

The main controller <NUM>, <NUM>, or <NUM> may not only control each of the hydraulic cylinders <NUM>, <NUM>, and <NUM> of the front work device <NUM> but also control an on-off control valve that interrupts and opens a hydraulic circuit by using an I/O digital output port included in the main controller <NUM>, <NUM>, or <NUM>.

In the foregoing embodiments, description has been made of an example in which the operation signal detected by the operation sensor 23a is voltage. However, the present invention is not limited to this. It suffices for the operation sensor 23a and the operation determining section <NUM> to be of a configuration in which the operation determining section <NUM> can determine the presence or absence of operation of the operation lever <NUM> on the basis of a result of detection in the operation sensor 23a. For example, the operation signal output from the operation sensor 23a may be a digital signal or a PWM signal, and the operation determining section <NUM> may determine the presence or absence of operation of the operation lever <NUM> on the basis of these operation signals. In addition, the type of the operation lever <NUM> is not limited to an electric lever type, but a hydraulic lever type may be used. In this case, it suffices to provide a pressure sensor to a pilot circuit that hydraulically transmits the operation signal, and use a detected pressure as the operation signal.

The conversion table (see <FIG>) between the voltage value and the current value as described in the foregoing embodiments is a mere example. The table may be changed optionally according to operation characteristics of the hydraulic actuator.

The configuration of the control system <NUM>, <NUM>, <NUM>, or <NUM> described in the foregoing embodiments is a mere example. Various configurations can be adopted as the configuration as long as the configurations enable a device (not shown) independent from the main controller <NUM>, <NUM>, or <NUM> to receive a command from the sub-controller <NUM>, <NUM>, <NUM>, or <NUM>, and control the supply of power to the main controller <NUM>, <NUM>, or <NUM>. For example, in the first embodiment, the battery <NUM> that supplies power to each of the controllers <NUM>, <NUM>, and <NUM> may be separately provided to each of the controllers <NUM>, <NUM>, and <NUM>.

In the foregoing embodiments, description has been made of an example in which the relay <NUM> is provided as a power interrupting unit that can interrupt the supply of power from the battery <NUM> to the main controller <NUM>, <NUM>, or <NUM>, and the supply of power to the main controller <NUM>, <NUM>, or <NUM> is controlled by controlling the opening and closing of the relay <NUM>. However, the present invention is not limited to this. For example, a configuration may be adopted in which power is supplied from the battery <NUM> to the main controller <NUM>, <NUM>, or <NUM> via the sub-controller <NUM>, <NUM>, <NUM>, or <NUM>, a power interrupting unit such as a switch circuit may be provided within the sub-controller <NUM>, <NUM>, <NUM>, or <NUM> in place of the relay <NUM>, and the supply of power from the battery <NUM> to the main controller <NUM>, <NUM>, or <NUM> may be interrupted by controlling the power interrupting unit. In addition, another controller (not shown) than the main controller <NUM>, <NUM>, or <NUM> may be provided in place of the relay <NUM>, and the other controller may directly supply power to the main controller <NUM>, <NUM>, or <NUM> or interrupt the power to the main controller <NUM>, <NUM>, or <NUM>.

In the foregoing embodiments, description has been made of an example in which the auto idle condition is satisfied when the operation lever <NUM> is not operated for a predetermined time. However, the present invention is not limited to this. For example, a configuration may be adopted in which operation signals of not only the operation lever <NUM> for operating the front work device <NUM> but also a travelling pedal (not shown) for operating the travelling of the track structure <NUM> are detected, and when neither of the operation signals of the operation lever <NUM> and the travelling pedal is detected for a predetermined time, it is determined that the auto idle condition is satisfied, and the auto idle control is performed.

In the foregoing embodiments, description has been made of an example in which when the auto idle condition is satisfied, auto idling control of the engine controller <NUM> is performed, and the main controller <NUM>, <NUM>, or <NUM> is restarted. However, the present invention is not limited to this. The auto idle control may not be performed when a predetermined condition is satisfied even when the above-described auto idle condition is satisfied and the auto idle activating command is output from the sub-controller <NUM>, <NUM>, <NUM>, or <NUM> to the engine controller <NUM>. For example, the engine controller <NUM>, even when the auto idle activating command is input to the engine controller <NUM>, may warm up the engine <NUM> by exceptionally performing control that maintains the engine revolution speed at a revolution speed higher than the idle revolution speed when a cooling water temperature is lower than a predetermined threshold value. Even in such a case, the sub-controller <NUM>, <NUM>, <NUM>, or <NUM> performs the power interruption control that interrupts the supply of power to the main controller <NUM>, <NUM>, or <NUM> when the auto idle condition is satisfied.

The foregoing embodiments have been described by taking the crawler type track structure (track device) <NUM> as an example. However, the present invention is not limited to this. The present invention can also be applied to a work machine having a wheeled track structure (track device) such as a wheeled hydraulic excavator or a wheel loader.

In the foregoing second embodiment, the shutoff lever <NUM> is used as a lock operation device. However, the present invention is not limited to this. It suffices for the lock device to be a device that can select enabling/disabling of operation of the operation lever <NUM>, such as a device that can interrupt a signal from the main controller <NUM>, <NUM>, or <NUM> to the proportional valve unit <NUM>, a device that can interrupt a signal (pilot pressure) from the proportional valve unit <NUM> to the control valve, or a device that can interrupt the hydraulic circuit between the proportional valve unit <NUM> and the pilot pump. For example, a pilot cut switch provided within the cab of a wheeled hydraulic excavator that can travel on a public road also has functions equivalent to those of the shutoff lever, and therefore the pilot cut switch may be used as the lock device.

In the foregoing third and fourth embodiments, description has been made of an example in which the ending processing performed by the main controller <NUM> or <NUM> stores various kinds of setting values in the internal memory <NUM>. However, the present invention is not limited to this. It suffices for the ending processing performed by the main controller <NUM> or <NUM> to be special processing performed only at an ending time (when the power to the main controller <NUM> or <NUM> is turned off). The ending processing may, for example, be processing of storing various kinds of setting values and a result of failure diagnosis (failure information or the like) in the sub-controller <NUM> or <NUM> outside the main controller <NUM> or <NUM> or an external apparatus such as an external server at an ending time.

In addition, as described above, configurations described in different embodiments may be combined with each other. For example, the shutoff lever <NUM> and the locked state determining section <NUM> in the second embodiment may be incorporated into the control system <NUM> or <NUM> in the third embodiment or the fourth embodiment, the ending processing by the main controller <NUM> or <NUM> may be performed only when the hydraulic excavator <NUM> is in the locked state, and the power interruption control that interrupts the supply of power to the main controller <NUM> or <NUM> may be performed when it is determined that the ending processing is completed in the locked state.

Description has been made of an example in which the battery <NUM> is provided as a power supply source. However, the present invention is not limited to this. The power supply source that supplies power to the main controller <NUM>, <NUM>, or <NUM> may be an electrical storage device such as a capacitor, or may be a generator.

Claim 1:
A work machine (<NUM>) comprising:
a work device (<NUM>); an operation device (<NUM>) operating the work device (<NUM>); a first controller (<NUM>) configured to control operation of the work device (<NUM>) on a basis of operation of the operation device (<NUM>); and a second controller (<NUM>, <NUM>) configured to determine that an auto idle condition is satisfied and perform auto idle control that decreases an engine revolution speed to an idle revolution speed in case the operation device (<NUM>) is not operated for a predetermined time, wherein
the first controller (<NUM>) is configured to diagnose presence or absence of a failure in the first controller (<NUM>) when supply of power to the first controller (<NUM>) is started, and
the second controller (<NUM>) is configured to perform power interruption control that interrupts the supply of the power to the first controller (<NUM>) in case the auto idle condition is satisfied, and perform power supply control that starts the supply of the power to the first controller (<NUM>) afterward.