Patent Description:
Patent Document <NUM>, for example, describes a technology of performing, in a construction machine, power reduction control referred to as auto idle control, which reduces power output by an engine as a power source by reducing the rotation speed of the engine during non-operation of control levers in order to reduce an amount of fuel consumed by the engine and thereby save energy consumption.

The construction machine that performs the power reduction control (auto idle control) of reducing the power output by the engine as a power source during non-operation of the control levers as described in Patent Document <NUM> is generally allowed to return to a normal power state by canceling the power reduction control when a control lever is operated. However, in the case where the power reduction control is performed in such a manner, when a hand erroneously hits a control lever, for example, a return to the normal power state is made by canceling the control although there is no intention of canceling the power reduction control. That is, although there should be no need to return the engine from a state in which the power is reduced to the normal state, the power reduction control of the engine is canceled. Thus, an effect of saving the energy consumption of the engine is reduced.

The present invention has been made in view of the above-described problems. It is an object of the present invention to provide a construction machine that can perform power reduction control during non-operation of control levers, and suppress power consumption of a power source and thus reduce energy consumption of the power source when a control lever is moved by an erroneous operation.

In order to solve such problems, according to the present invention, there is provided a construction machine including: a power source; a plurality of actuators that operate by receiving power from the power source; a plurality of control levers that instruct amounts of the power to be distributed to the plurality of actuators; a plurality of operation state sensors that detect operation states of the plurality of control levers; and a controller that controls the power output by the power source, the controller being configured to perform power reduction control of the power source on a basis of the operation states of the plurality of control levers detected by the plurality of operation state sensors when a non-operation time of the plurality of control levers exceeds a set time after a transition is made from a state in which at least one of the plurality of control levers is operated to a non-operation state in which none of the plurality of control levers is operated, and to cancel the power reduction control when at least one of the plurality of control levers is operated in a state in which the power reduction control is performed. Further, in the construction machine, the controller is configured to set the set time as a first set time when an operation time until the at least one control lever makes a transition to the non-operation state is longer than a monitoring time set in advance, and set the set time as a second set time shorter than the first set time when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time set in advance.

In this way, the controller is configured to set the set time as the second set time shorter than the first set time when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time set in advance. Consequently, when a control lever is moved by an erroneous operation, the power reduction control is temporarily canceled to return to a normal power state, but a return is thereafter made to a power reduction state in a short time. It is therefore possible to suppress power consumption of the power source and thus reduce energy consumption of the power source when a control lever is moved by an erroneous operation.

According to the present invention, it is possible to perform power reduction control during non-operation of the control levers, and suppress power consumption of the power source when a control lever is moved by an erroneous operation, and thus reduce energy consumption of the power source.

Embodiments of the present invention will hereinafter be described according to the drawings.

A first embodiment of the present invention will be described with reference to <FIG>.

~ Description will first be made of a hydraulic excavator as a typical example of a construction machine in the first embodiment of the present invention.

<FIG> is a diagram showing an external appearance of a hydraulic excavator in the present embodiment.

The hydraulic excavator includes a lower track structure <NUM>, an upper swing structure <NUM> swingably mounted on the lower track structure, and a swing type front work implement <NUM> attached to a front portion of the upper swing structure so as to be rotatable in an upward-downward direction. The front work implement <NUM> includes a boom <NUM>, an arm <NUM>, and a bucket <NUM>. The upper swing structure <NUM> and the lower track structure <NUM> are rotatably connected to each other by a swing wheel <NUM>. The upper swing structure <NUM> is swingable with respect to the lower track structure <NUM> by rotation of a swing motor <NUM>. A swing post <NUM> is attached to a front portion of the upper swing structure <NUM>. The front work implement <NUM> is attached to the swing post <NUM> so as to be vertically movable. The swing post <NUM> is rotatable with respect to the upper swing structure <NUM> in a horizontal direction by expansion and contraction of a swing cylinder (not shown). The boom <NUM>, the arm <NUM>, and the bucket <NUM> of the front work implement <NUM> are rotatable in the upward-downward direction by expansion and contraction of a boom cylinder <NUM>, an arm cylinder <NUM>, and a bucket cylinder <NUM> as a first front implement actuator, a second front implement actuator, and a third front implement actuator. Attached to a central frame of the lower track structure <NUM> are a right and a left track device 105a and 105b and a blade <NUM> that moves up and down according to expansion and contraction of a blade cylinder <NUM>. The right and left track devices 105a and 105b include driving wheels 210a and 210b, idlers 211a and 211b, and crawlers 212a and 212b, respectively. The right and left track devices 105a and 105b travel by transmitting rotation of a right and a left travelling motor 3f and <NUM> to the driving wheels 210a and 210b, and thereby driving the crawlers 212a and 212b.

A cabin <NUM> in which a cab <NUM> is formed is installed on the upper swing structure <NUM>. The cab <NUM> is provided with a cab seat <NUM> and a right and a left control lever device <NUM> and <NUM> that instruct driving of the boom cylinder <NUM>, the arm cylinder <NUM>, the bucket cylinder <NUM>, and the swing motor <NUM>. In addition, similar control lever devices are provided also for the travelling motors 3f and <NUM>, the blade cylinder <NUM>, and the swing cylinder not shown. These control lever devices are also provided in the cab <NUM>.

Description will next be made of a driving system included in the construction machine (hydraulic excavator) according to the present embodiment. <FIG> is a diagram showing a configuration of the driving system according to the present embodiment.

In <FIG>, the driving system includes an engine <NUM> (diesel engine) as well as a main hydraulic pump <NUM> and a pilot pump <NUM>. The hydraulic pump <NUM> and the pilot pump <NUM> are driven by the engine <NUM>. The hydraulic pump <NUM> is connected to a line <NUM>. A relief valve <NUM> is attached to the line <NUM> via a relief line <NUM>. The downstream side of the relief valve <NUM> is connected to a tank <NUM>. A line <NUM> and a line <NUM> are connected downstream of the line <NUM>. Lines <NUM>, <NUM>, <NUM>, and <NUM> are connected in parallel to the line <NUM>. Check valves <NUM>, <NUM>, <NUM>, and <NUM> are arranged on the lines <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

A directional control valve <NUM> is connected downstream of the line <NUM> and the line <NUM>. The directional control valve <NUM> is also connected with a bottom line 13B connected to a bottom side chamber of the boom cylinder <NUM>, a rod line 13R connected to a rod side chamber of the boom cylinder <NUM>, a tank line 13T connected to the tank <NUM>, and a center bypass line 13C.

The directional control valve <NUM> is driven by the pressure of a pilot line 12b and the pressure of a pilot line 12r. When the pressures of both pilot lines are low, the directional control valve <NUM> is at a neutral position so that the line <NUM> is connected to the center bypass line 13C and the other lines are interrupted. When the pressure of the pilot line 12b is high, the directional control valve <NUM> is switched upward in the figure so that the line <NUM> is connected to the bottom line 13B, the tank line 13T is connected to the rod line 13R, and the line <NUM> and the center bypass line 13C are interrupted. When the pressure of the pilot line 12r is high, the directional control valve <NUM> is switched downward in the figure so that the line <NUM> is connected to the rod line 13R, the tank line 13T is connected to the bottom line 13B, and the line <NUM> and the center bypass line 13C are interrupted.

A directional control valve <NUM> is connected downstream of the line 13C and the line <NUM>. The directional control valve <NUM> is also connected with a bottom line 23B connected to a bottom side chamber of the arm cylinder <NUM>, a rod line 23R connected to a rod side chamber of the arm cylinder <NUM>, a tank line 23T connected to the tank <NUM>, and a center bypass line 23C.

The directional control valve <NUM> is driven by the pressure of a pilot line 22b and the pressure of a pilot, line 22r. When the pressures of both pilot lines are low, the directional control valve <NUM> is at a neutral position so that the center bypass line 13C is connected to the center bypass line 23C and the other lines are interrupted. When the pressure of the pilot line 22b is high, the directional control valve <NUM> is switched upward in the figure so that the line <NUM> is connected to the bottom line 23B, the tank line 23T is connected to the rod line 23R, and the center bypass line 13C and the center bypass line 23C are interrupted. When the pressure of the pilot line 22r is high, the directional control valve <NUM> is switched downward in the figure so that the line <NUM> is connected to the rod line 23R, the tank line 23T is connected to the bottom line 23B, and the center bypass line 13C and the center bypass line 23C are interrupted.

A directional control valve <NUM> is connected downstream of the line 23C and the line <NUM>. The directional control valve <NUM> is also connected with a bottom line 33B connected to a bottom side chamber of the bucket cylinder <NUM>, a rod line 33R connected to a rod side chamber of the bucket cylinder <NUM>, a tank line 33T connected to the tank <NUM>, and a center bypass line 33C.

The directional control valve <NUM> is driven by the pressure of a pilot line 32b and the pressure of a pilot line 32r. When the pressures of both of the pilot lines are low, the directional control valve <NUM> is at a neutral position so that the center bypass line 23C is connected to the center bypass line 33C and the other lines are interrupted. When the pressure of the pilot line 32b is high, the directional control valve <NUM> is switched upward in the figure so that the line <NUM> is connected to the bottom line 33B, the tank line 33T is connected to the rod line 33R, and the center bypass line 23C and the center bypass line 33C are interrupted. When the pressure of the pilot line 32r is high, the directional control valve <NUM> is switched downward in the figure so that the line <NUM> is connected to the rod line 33R, the tank line 33T is connected to the bottom line 33B, and the center bypass line 23C and the center bypass line 33C are interrupted.

A directional control valve <NUM> is connected downstream of the line 33C and the line <NUM>. The directional control valve <NUM> is also connected with a left rotation line <NUM> connected to a left rotation side chamber of the swing motor <NUM>, a right rotation line 43R connected to a right rotation side chamber of the swing motor <NUM>, a tank line 43T connected to the tank <NUM>, and a center bypass line 43C. The center bypass line 43C is connected to the tank <NUM>.

The directional control valve <NUM> is driven by the pressure of a pilot line <NUM> and the pressure of a pilot line 42r. When the pressures of both of the pilot lines are low, the directional control valve <NUM> is at a neutral position so that the center bypass line 33C is connected to the center bypass line 43C and the other lines are interrupted. When the pressure of the pilot line <NUM> is high, the directional control valve <NUM> is switched upward in the figure so that the line <NUM> is connected to the left rotation line <NUM>, the tank line 43T is connected to the right rotation line 43R, and the center bypass line 33C and the center bypass line 43C are interrupted. When the pressure of the pilot line 42r is high, the directional control valve <NUM> is switched downward in the figure so that the line <NUM> is connected to the right rotation line 43R, the tank line 43T is connected to the left rotation line <NUM>, and the center bypass line 33C and the center bypass line 43C are interrupted.

The pilot pump <NUM> is connected to a pilot line <NUM>. The downstream of the pilot line <NUM> will be described later with reference to <FIG>.

Incidentally, though not shown, the hydraulic drive system has similar directional control valves provided also for the travelling motors 3f and <NUM> and the blade cylinder <NUM> shown in <FIG> and the swing cylinder not shown in the figure so that the connection and interruption of lines can be performed.

Here, the engine <NUM> and the hydraulic pump <NUM> constitute a power source, and the boom cylinder <NUM>, the arm cylinder <NUM>, the bucket cylinder <NUM>, the swing motor <NUM>, the travelling motors 3f and <NUM>, the blade cylinder <NUM>, and the swing cylinder not shown constitute a plurality of actuators that are actuated by receiving power from the power source. A plurality of control levers of the control lever devices <NUM> and <NUM> shown in <FIG> and the other control lever devices not shown each instruct amounts of power to be distributed to the plurality of actuators. The directional control valves <NUM>, <NUM>, <NUM>, and <NUM> and the other directional control valves not shown distribute power to the plurality of actuators on the basis of the instructions of the plurality of control levers.

Configurations of control lever devices will next be described with reference to <FIG> and <FIG>. <FIG> is a diagram of assistance in explaining movable directions of the control levers of the control lever devices <NUM> and <NUM> in the first embodiment and definitions of the movable directions.

As described with reference to <FIG>, the right and left control lever devices <NUM> and <NUM> are installed in the cab <NUM> of the hydraulic excavator. An operator operates a control lever <NUM> (first control lever) of the control lever device <NUM> with a right hand, and operates a control lever <NUM> (second control lever) of the control lever device <NUM> with a left hand. The control lever devices <NUM> and <NUM> each allow two actuators to be operated by one control lever <NUM> or <NUM>. The control levers <NUM> and <NUM> can each be operated from a neutral position. Operations of the control lever <NUM> in a forward direction 14b and a rearward direction 14r correspond to operations of boom lowering and boom raising of the boom cylinder <NUM>. Operations of the control lever <NUM> in a right direction 24r and a left direction 24b correspond to operations of bucket dumping and bucket crowding of the bucket cylinder <NUM>. Operations of the control lever <NUM> in a right direction 34b and a left direction 34r correspond to operations of arm crowding and arm dumping of the arm cylinder <NUM>. Operations of the control lever <NUM> in a forward direction <NUM> and a rearward direction 44r correspond to operations of right swinging and left swinging of the swing motor <NUM>. Incidentally, the forward direction, the rearward direction, the right direction, and the left direction in the present specification refer to a front direction, a rear direction, a right direction, and a left direction of the upper swing structure <NUM> as a machine body.

Thus, the control levers <NUM> and <NUM> of the control lever devices <NUM> and <NUM> can be operated in the plurality of directions from the neutral position, and operate different actuators among the plurality of actuators (the boom cylinder <NUM>, the arm cylinder <NUM>, the bucket cylinder <NUM>, and the swing motor <NUM>).

<FIG> is a diagram showing a configuration of an operating system of the driving system.

In <FIG>, the control lever devices <NUM> and <NUM> are of a hydraulic pilot type, the control lever device <NUM> includes pilot valves 15b and 15r for the boom and pilot valves 25b and 25r for the bucket, the pilot valves 15b and 15r and the pilot valves 25b and 25r driven by the control lever <NUM> (first lever), and the control lever device <NUM> includes pilot valves 35b and 35r for the arm and pilot valves <NUM> and 45r for swinging, the pilot valves 35b and 35r and the pilot valves <NUM> and 45r driven by the control lever <NUM> (second lever). In the following description, the control levers may be referred to simply as "levers.

Lines <NUM>, <NUM>, <NUM>, and <NUM> and a relief valve <NUM> are connected in parallel with each other downstream of the pilot line <NUM>. The tank <NUM> is connected downstream of the relief valve <NUM>. The lines <NUM>, <NUM>, <NUM>, and <NUM> are provided with restricting sections <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

The pilot valve 15b of the control lever device <NUM> is connected to the line <NUM>, and is connected to a line <NUM> and a line 16b. The line 16b is connected to the pilot line 12b (see <FIG>). A pressure sensor 17b is attached onto the line 16b. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 15b connects the line <NUM> and the line 16b to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the forward direction 14b, the pilot valve 15b connects the line <NUM> and the line 16b to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 16b.

The pressure sensor 17b measures the pressure of the line 16b, and transmits a signal to a controller <NUM> electrically connected to the pressure sensor 17b.

The pilot valve 15r of the control lever device <NUM> is connected to the line <NUM>, and is connected to the line <NUM> and a line 16r. The line 16r is connected to the pilot line 12r (see <FIG>). A pressure sensor 17r is attached onto the line 16r. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 15r connects the line <NUM> and the line 16r to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the rearward direction 14r, the pilot valve 15r connects the line <NUM> and the line 16r to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 16r.

The pressure sensor 17r measures the pressure of the line 16r, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 17r.

The pilot valve 25b of the control lever device <NUM> is connected to the line <NUM>, and is connected to a line <NUM> and a line 26b. The line 26b is connected to the pilot line 32b (see <FIG>). A pressure sensor 27b is attached onto the line 26b. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 25b connects the line <NUM> and the line 26b to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the left direction 24b, the pilot valve 25b connects the line <NUM> and the line 26b to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 26b.

The pressure sensor 27b measures the pressure of the line 26b, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 27b.

The pilot valve 25r of the control lever device <NUM> is connected to the line <NUM>, and is connected to the line <NUM> and a line 26r. The line 26r is connected to the pilot line 32r (see <FIG>). A pressure sensor 27r is attached onto the line 26r. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 25r connects the line <NUM> and the line 26r to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the right direction 24r, the pilot valve 25r connects the line <NUM> and the line 26r to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 26r.

The pressure sensor 27r measures the pressure of the line 26r, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 27r.

The pilot valve 35b of the control lever device <NUM> is connected to the line <NUM>, and is connected to a line <NUM> and a line 36b. The line 36b is connected to the pilot line 22b (see <FIG>). A pressure sensor 37b is attached onto the line 36b. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 35b connects the line <NUM> and the line 36b to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the right direction 34b, the pilot valve 35b connects the line <NUM> and the line 36b to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 36b.

The pressure sensor 37b measures the pressure of the line 36b, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 37b.

The pilot valve 35r of the control lever device <NUM> is connected to the line <NUM>, and is connected to the line <NUM> and a line 36r. The line 36r is connected to the pilot line 22r (see <FIG>). A pressure sensor 37r is attached onto the line 36r. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 35r connects the line <NUM> and the line 36r to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the left direction 34r, the pilot valve 35r connects the line <NUM> and the line 36r to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 36r.

The pressure sensor 37r measures the pressure of the line 36r, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 37r.

The pilot valve <NUM> of the control lever device <NUM> is connected to the line <NUM>, and is connected to a line <NUM> and a line <NUM>. The line <NUM> is connected to the pilot line <NUM> (see <FIG>). A pressure sensor <NUM> is attached onto the line <NUM>. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve <NUM> connects the line <NUM> and the line <NUM> to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the forward direction <NUM>, the pilot valve <NUM> connects the line <NUM> and the line <NUM> to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line <NUM>.

The pressure sensor <NUM> measures the pressure of the line <NUM>, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor <NUM>.

The pilot valve 45r of the control lever device <NUM> is connected to the line <NUM>, and is connected to the line <NUM> and a line 46r. The line 46r is connected to the pilot line 42r (see <FIG>). A pressure sensor 47r is attached onto the line 46r. The line <NUM> is connected to the tank <NUM>.

When the lever <NUM> is at the neutral position, the pilot valve 45r connects the line <NUM> and the line 46r to each other, and interrupts the line <NUM>. When the lever <NUM> is operated in the rearward direction 44r, the pilot valve 45r connects the line <NUM> and the line 46r to each other, and interrupts the line <NUM>. At this time, a pressure (operation pressure) corresponding to an operation amount of the lever <NUM> is generated in the line 46r.

The pressure sensor 47r measures the pressure of the line 46r, and transmits a signal to the controller <NUM> electrically connected to the pressure sensor 47r.

The pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r constitute a plurality of operation state sensors that detect operation states of the control lever devices <NUM> and <NUM>. In addition, the pressure sensors 17b. and 17r constitute a first operation state sensor that detects the operation state in a forward-rearward direction of the control lever <NUM>. The pressure sensors 27b and 27r constitute a second operation state sensor that detects the operation state in a right-left direction of the control lever <NUM>. The pressure sensors 37b and 37r constitute a third operation state sensor that detects the operation state in the right-left direction of the control lever <NUM>. The pressure sensors <NUM> and 47r constitute a fourth operation state sensor that detects the operation state in the forward-rearward direction of the control lever <NUM>.

Incidentally, though not shown, the operating system has similar pressure sensors (operation state sensors) provided also for the control lever devices other than the control lever devices <NUM> and <NUM>, and power reduction control to be described later can be performed on the basis of the operation states of the control levers of these control lever devices.

Returning to <FIG>, the driving system according to the present embodiment further include the controller <NUM>, a switch <NUM>, and a target rotation speed indicating device <NUM>.

The controller <NUM> is electrically connected to the pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r, the switch <NUM>, and the target rotation speed indicating device <NUM>. The controller <NUM> receives signals of measured pressures from the pressure sensors 17b to 47r, a signal from the switch <NUM>, and a signal from the target rotation speed indicating device <NUM>, computes a target rotation speed for controlling the engine <NUM> on the basis of these signals, and transmits a command signal of the target rotation speed to a rotation speed controller <NUM> of the engine <NUM>, which is electrically connected to the controller <NUM>. The rotation speed controller <NUM> controls the engine <NUM> so as to achieve the target rotation speed.

The switch <NUM> is a switch that selects whether to set a power reduction control mode by transmitting an ON or OFF signal to the controller <NUM>. When the signal of the switch <NUM> is OFF, the power reduction control mode is canceled, and driving power of the engine <NUM> is not reduced even if all of the control levers are in a non-operation state.

Functions of the controller <NUM> in the first embodiment will next be described. <FIG> is a block diagram showing functions of the controller <NUM>.

A basic concept of control performed by the controller <NUM> will first be described.

The controller <NUM> performs power reduction control of the engine <NUM> and the hydraulic pump <NUM> (power source) on the basis of the operation states of the control levers <NUM> and <NUM> (plurality of control levers) detected by the pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r (plurality of operation state sensors) when a non-operation time of the control levers <NUM> and <NUM> exceeds a set time after a transition is made from a state in which at least one of the control levers <NUM> and <NUM> is operated to a non-operation state in which none of the control levers <NUM> and <NUM> is operated. The controller <NUM> cancels the power reduction control when at least one of the control levers <NUM> and <NUM> is operated in a state in which the power reduction control is performed.

In addition, as characteristic functions of the controller <NUM>, the controller <NUM> sets the above-described set time as a first set time Tth1 when an operation time until at least one control lever makes a transition to the non-operation state is longer than a monitoring time Tth0 set in advance, and sets the above-described set time as a second set time Tth2 shorter than the first set time Tth1 when the time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time Tth0 set in advance.

In addition, the controller <NUM> generates non-operation flags F14(t) and F34(t) (non-operation state information) indicating that the control levers <NUM> and <NUM> are in a non-operation state and a power reduction flag F50(t) (power reduction control state information) indicating that the power reduction control is performed on the basis of the operation states of the control levers <NUM> and <NUM> (plurality of control levers) detected by the pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r (plurality of operation state sensors), calculates a power non-reduction time during which the power reduction control is not performed on the basis of the non-operation flags F14(t) and F34(t) and the power reduction flag F50(t), and uses the power non-reduction time as the operation time of the control levers <NUM> and <NUM>.

Further, the controller <NUM> determines that the operation of the at least one control lever is an erroneous operation when the transition is made from the state in which the at least one control lever is operated to the non-operation state in which none of the control levers <NUM> and <NUM> is operated and when the at least one control lever becomes non-operated during the monitoring time Tth0.

Details of the above-described basic concept of the controller <NUM> will be described in the following. Incidentally, in the following, description of the power reduction control based on the operation states of the control levers other than the control levers <NUM> and <NUM> will be omitted, and the power reduction control will be described with the operation states of the control levers <NUM> and <NUM> as a representative.

In <FIG>, the controller <NUM> has respective functions of a sensor signal converting section 50a, a constant and table storage section 50b, and a power computing section 50c.

The sensor signal converting section 50a receives signals sent from the pressure sensors 17b to 47r and the switch <NUM>, and converts the signals into pressure information and switch flag information. The sensor signal converting section 50a transmits the converted pressure information and the converted switch flag information to the power computing section 50c. The pressure information converted by the sensor signal converting section 50a is pressures generated in the lines 16b to 46r by driving the pilot valves 15b to 45r, and is shown as sensor values P17b(t), P17r(t), P27b(t), P27r(t), P37b(t), P37r(t), P47l(t), and P47r(t) in <FIG>. The sensor values P17b(t), P17r(t), P27b(t), P27r(t), P37b(t), P37r(t), P47l(t), and P47r(t) may be referred to also as "operation pressures. " In addition, as for the switch information converted by the sensor signal converting section 50a, in <FIG>, the switch flag information is shown as a switch flag Fsw(t). The switch flag Fsw(t) is Fsw(t) = true (enabled) when the switch <NUM> is ON. The switch flag Fsw(t) is Fsw(t) = false (disabled) when the switch <NUM> is OFF.

The constant and table storage section 50b stores constants and tables necessary for calculation. The constant and table storage section 50b transmits these pieces of information to the power computing section 50c. The constants stored in the constant and table storage section 50b include the monitoring time Tth0, the first set time Tth1, and the second set time Tth2 described above.

The power computing section 50c receives the pressure information and the switch flag information transmitted from the sensor signal converting section 50a, target rotation speed information transmitted from the target rotation speed indicating device <NUM>, and constant information (the monitoring time Tth0, the first set time Tth1, and the second set time Tth2) and table information transmitted from the constant and table storage section 50b, and computes the target rotation speed of the engine <NUM>. Then, the power computing section 50c outputs the target rotation speed for control to the rotation speed controller <NUM>.

Functions of the power computing section 50c in the first embodiment will next be described. <FIG> is a block diagram showing functions of the power computing section 50c. Incidentally, suppose that a sampling time of the controller <NUM> is Δt.

In <FIG>, the power computing section 50c has respective functions of a lever <NUM> operation state determining section 50c-<NUM>, a lever <NUM> operation state determining section 50c-<NUM>, a lever <NUM> non-operation time measuring section 50c-<NUM>, a lever <NUM> non-operation time measuring section 50c-<NUM>, a power reduction determining section 50c-<NUM>, a delay element 50c-<NUM>, and a power non-reduction time measuring section 50c-<NUM>.

The lever <NUM> operation state determining section 50c-<NUM> determines whether the lever <NUM> is operated from the sensor values P17b(t), P17r(t), P27b(t), and P27r(t), and outputs the lever <NUM> non-operation flag F14(t). The lever <NUM> operation state determining section 50c-<NUM> sets the lever <NUM> non-operation flag F14(t) true when determining that the lever <NUM> is not operated. The lever <NUM> operation state determining section 50c-<NUM> sets the lever <NUM> non-operation flag F14(t) false when determining that the lever <NUM> is operated. This lever <NUM> non-operation flag F14(t) (which may hereinafter be referred to simply as flag information F14(t) is transmitted to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power non-reduction time measuring section 50c-<NUM>.

The lever <NUM> operation state determining section 50c-<NUM> determines whether the lever <NUM> is operated from the sensor values P37b(t), P37r(t), P47l(t), and P47r(t), and outputs the lever <NUM> non-operation flag F34(t). The lever <NUM> non-operation state determining section 50c-<NUM> sets the lever <NUM> non-operation flag F34(t) true when determining that the lever <NUM> is not operated. The lever <NUM> non-operation state determining section 50c-<NUM> sets the lever <NUM> non-operation flag F34(t) false when determining that the lever <NUM> is operated. This lever <NUM> non-operation flag F34(t) (which may hereinafter be referred to simply as flag information F34(t)) is transmitted to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power non-reduction time measuring section 50c-<NUM>.

The lever <NUM> non-operation time measuring section 50c-<NUM> measures a lever <NUM> non-operation time Tu14(t) on the basis of the flag information F14(t), and transmits the lever <NUM> non-operation time Tu14(t) (which may hereinafter be referred to simply as time information Tu14(t)) to the power reduction determining section 50c-<NUM>.

The lever <NUM> non-operation time measuring section 50c-<NUM> measures a lever <NUM> non-operation time Tu34(t) on the basis of the flag information F34(t), and transmits the lever <NUM> non-operation time Tu34(t) (which may hereinafter be referred to simply as time information Tu34(t)) to the power reduction determining section 50c-<NUM>.

The power non-reduction time measuring section 50c-<NUM> measures a power non-reduction time TF50(t) on the basis of the flag information F14(t) and the flag information F34(t) and a power reduction flag F50(t - Δt) preceding by one step, which is generated by the delay element 50c-<NUM>, and transmits the power non-reduction time TF50(t) (which may hereinafter be referred to simply as time information TF50(t)) to the power reduction determining section 50c-<NUM>.

The power reduction determining section 50c-<NUM> determines whether to reduce the target rotation speed for control on the basis of the time information Tu14(t) and Tu34(t) and the time information TF50(t), the switch flag Fsw(t), and the target rotation speed transmitted from the target rotation speed indicating device <NUM>, and outputs the target rotation speed for control and the power reduction flag F50(t) on the basis of a result of the determination. In addition, the power reduction determining section 50c-<NUM> sets the power reduction flag F50(t) true when determining that the target rotation speed is to be reduced, and the power reduction determining section 50c-<NUM> sets the power reduction flag F50(t) false when determining that the target rotation speed is not to be reduced.

Functions of the lever <NUM> operation state determining section 50c-<NUM> in the first embodiment will next be described. <FIG> is a flowchart showing a computation flow of the lever <NUM> operation state determining section 50c-<NUM>. This computation flow is processed repeatedly in each sampling time Δt while the controller <NUM> operates, for example.

The computation of the lever <NUM> operation state determining section 50c-<NUM> is started in step S101.

In step S102, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P17b(t) is equal to or smaller than a threshold value Pth. When the sensor value P17b(t) is equal to or less than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S103. When the sensor value P17b(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S107.

In step S103, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P17r(t) is equal to or smaller than the threshold value Pth. When the sensor value P17r(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S104. When the sensor value P17r(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S107.

In step S104, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P27b(t) is equal to or smaller than the threshold value Pth. When the sensor value P27b(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S105. When the sensor value P27b(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S107.

In step S105, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P27r(t) is equal to or smaller than the threshold value Pth. When the sensor value P27r(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S106. When the sensor value P27r(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S107.

In step S106, the lever <NUM> operation state determining section 50c-<NUM> determines that the lever <NUM> is not operated, and sets the lever <NUM> non-operation flag F14(t) true. Then, the lever <NUM> operation state determining section 50c-1transmits the flag information to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power reduction determining section 50c-<NUM>.

In step S107, the lever <NUM> operation state determining section 50c-<NUM> determines that the lever <NUM> is operated, and sets the lever <NUM> non-operation flag F14(t) false. Then, the lever <NUM> operation state determining section 50c-<NUM> transmits the flag information to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power reduction determining section 50c-<NUM>.

The computation of the lever <NUM> operation state determining section 50c-<NUM> is started in step S201.

In step S202, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P37b(t) is equal to or smaller than the threshold value Pth. When the sensor value P37b(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S203. When the sensor value P37b(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S207.

In step S203, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P37r(t) is equal to or smaller than the threshold value Pth. When the sensor value P37r(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S204. When the sensor value P37r(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S207.

In step S204, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P47l(t) is equal to or smaller than the threshold value Pth. When the sensor value P47l(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S205. When the sensor value P471(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S207.

In step S205, the lever <NUM> operation state determining section 50c-<NUM> determines whether the sensor value P47r(t) is equal to or smaller than the threshold value Pth. When the sensor value P47r(t) is equal to or smaller than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S206. When the sensor value P47r(t) is larger than the threshold value Pth, the lever <NUM> operation state determining section 50c-<NUM> determines No, and proceeds to the processing of step S207.

In step S206, the lever <NUM> operation state determining section 50c-<NUM> determines that the lever <NUM> is not operated, and sets the lever <NUM> non-operation flag F34(t) true. Then, the lever <NUM> operation state determining section 50c-<NUM> transmits the flag information to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power reduction determining section 50c-<NUM>.

In step S207, the lever <NUM> operation state determining section 50c-<NUM> determines that the lever <NUM> is operated, and sets the lever <NUM> non-operation flag F34(t) false. Then, the lever <NUM> operation state determining section 50c-<NUM> transmits the flag information to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power reduction determining section 50c-<NUM>.

A definition of the threshold value Pth for the above-described sensor values will be described with reference to <FIG> shows relation between the sensor value P17b(t) or P17r(t) and the meter-in opening area of the directional control valve <NUM>. In addition, the sensor value P17b(t) or P17r(t) is represented as an "operation pressure.

In <FIG>, until the operation pressure P17b(t) or P17r(t) becomes the value of Pth, a meter-in opening does not open, and therefore the hydraulic cylinder (boom cylinder) <NUM> is not actuated. This relation is the same for the other directional control valves. The operation state determining sections 50c-<NUM> and 50c-<NUM> use the pressure value Pth at which the meter-in opening opens as a threshold value.

Functions of the lever <NUM> non-operation time measuring section 50c-<NUM> in the first embodiment will next be described. <FIG> is a flowchart showing a computation flow of the lever <NUM> non-operation time measuring section 50c-<NUM>. This computation flow is processed repeatedly in each sampling time Δt while the controller <NUM> operates, for example.

The computation of the lever <NUM> non-operation time measuring section 50c-<NUM> is started in step S301.

In step S302, the lever <NUM> non-operation time measuring section 50c-<NUM> determines whether the lever14 non-operation flag F14(t) is true. When the lever <NUM> non-operation flag F14(t) is true, the lever <NUM> non-operation time measuring section 50c-<NUM> determines Yes, and proceeds to the processing of step S303. When the lever <NUM> non-operation flag F14(t) is false, the lever <NUM> non-operation time measuring section 50c-<NUM> determines No, and proceeds to the processing of step S304.

In step S303, since the lever <NUM> is not operated, the lever <NUM> non-operation time measuring section 50c-<NUM> sets, as a new lever <NUM> non-operation time Tu14(t), a value obtained by adding a sampling time Δt to a retained lever <NUM> non-operation time Tu14(t - Δt) preceding by one step. Then, the lever <NUM> non-operation time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

In step S304, since the lever <NUM> is operated, the lever <NUM> non-operation time measuring section 50c-<NUM> sets the lever <NUM> non-operation time Tu14(t) to zero. Then, the lever <NUM> non-operation time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

The computation of the lever <NUM> non-operation time measuring section 50c-<NUM> is started in step S401.

In step S402, the lever <NUM> non-operation time measuring section 50c-<NUM> determines whether the lever <NUM> non-operation flag F34(t) is true. When the lever <NUM> non-operation flag F34(t) is true, the lever <NUM> non-operation time measuring section 50c-<NUM> determines Yes, and proceeds to the processing of step S403. When the lever <NUM> non-operation flag F34(t) is false, the lever <NUM> non-operation time measuring section 50c-<NUM> determines No, and proceeds to the processing of step S404.

In step S403, since the lever <NUM> is not operated, the lever <NUM> non-operation time measuring section 50c-<NUM> sets, as a new lever <NUM> non-operation time Tu34(t), a value obtained by adding a sampling time Δt to a retained lever <NUM> non-operation time Tu34(t - Δt) preceding by one step. Then, the lever <NUM> non-operation time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

In step S404, since the lever <NUM> is operated, the lever <NUM> non-operation time measuring section 50c-<NUM> sets the lever <NUM> non-operation time Tu34(t) to zero. Then, the lever <NUM> non-operation time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

Functions of the power non-reduction time measuring section 50c-<NUM> in the first embodiment will next be described. <FIG> is a flowchart showing a computation flow of the power non-reduction time measuring section 50c-<NUM>. This computation flow is processed repeatedly in each sampling time Δt while the controller <NUM> operates, for example.

The computation of the power non-reduction time measuring section 50c-<NUM> is started in step S1401.

In step S1402, the power non-reduction time measuring section 50c-<NUM> determines whether the power reduction flag F50(t - Δt) preceding by one step is false. When the power reduction flag F50(t - Δt) is false, the power non-reduction time measuring section 50c-<NUM> determines Yes, and proceeds to the processing of step S1403. When the power reduction flag F50(t - Δt) is true, the power non-reduction time measuring section 50c-<NUM> determines No, and proceeds to the processing of step S1407.

In step S1403, the power non-reduction time measuring section 50c-<NUM> determines whether the lever <NUM> non-operation flag F14(t) is true. When the lever <NUM> non-operation flag F14(t) is true, the power non-reduction time measuring section 50c-<NUM> determines Yes, and proceeds to the processing of step S1404. When the lever <NUM> non-operation flag F14(t) is false, the power non-reduction time measuring section 50c-<NUM> determines No, and proceeds to the processing of step S1406.

In step S1404, the power non-reduction time measuring section 50c-<NUM> determines whether the lever <NUM> non-operation flag F34(t) is true. When the lever <NUM> non-operation flag F34(t) is true, the power non-reduction time measuring section 50c-<NUM> determines Yes, and proceeds to the processing of step S1405. When the lever <NUM> non-operation flag F34(t) is false, the power non-reduction time measuring section 50c-<NUM> determines No, and proceeds to the processing of step S1406.

In step S1406, since the power reduction flag F50(t - Δt) is false and thus does not indicate a power reduction state, and at least one of the lever <NUM> non-operation flag F14(t) and the lever <NUM> non-operation flag F34(t) is not true (at least one of the levers <NUM> and <NUM> is operated), the power non-reduction time measuring section 50c-<NUM> sets, as a new power non-reduction time TF50(t), a value obtained by adding a sampling time Δt to the power non-reduction time TF50(t - Δt) preceding by one step. Then, the power non-reduction time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

In step S1405, when the power reduction flag F50(t - Δt) is false and thus does not indicate a power reduction state, and both the lever <NUM> non-operation flag F14(t) and the lever <NUM> non-operation flag F34(t) become true (both of the levers <NUM> and <NUM> become non-operated), the power non-reduction time measuring section 50c-<NUM> sets the power non-reduction time TF50(t - Δt) preceding by one step as a new power non-reduction time TF50(t), and retains the power non-reduction time TF50(t - Δt) preceding by one step as the power non-reduction time TF50(t). Then, the power non-reduction time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

Here, the power non-reduction time TF50(t) set in step S1405 (power non-reduction time TF50(t - Δt) preceding by one step) means an operation time from a time that at least one of the levers <NUM> and <NUM> is operated (power reduction control is canceled) to a time that both of the levers <NUM> and <NUM> become non-operated (power reduction control is performed again).

In step S1407, since the power reduction flag F50(t - Δt) is not false and thus indicates a power reduction state, the power non-reduction time measuring section 50c-<NUM> sets the power non-reduction time TF50(t) to zero. Then, the power non-reduction time measuring section 50c-<NUM> transmits the information to the power reduction determining section 50c-<NUM>.

Functions of the power reduction determining section 50c-<NUM> in the first embodiment will next be described. <FIG> is a flowchart showing a computation flow of the power reduction determining section 50c-<NUM>. This computation flow is processed repeatedly in each sampling time Δt while the controller <NUM> operates, for example.

The computation of the power reduction determining section 50c-<NUM> is started in step S501.

In step S502, the power reduction determining section 50c-<NUM> determines whether the switch flag Fsw(t) is true. When the switch flag Fsw(t) is true, the power reduction determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S503. When the switch flag Fsw(t) is false, the power reduction determining section 50c-<NUM> determines No, and proceeds to the processing of step S509.

In step S503, the power reduction determining section 50c-<NUM> determines whether the power non-reduction time TF50(t) is equal to or more than a preset monitoring time Tth0 for an erroneous operation of the lever <NUM> or <NUM>. When the power non-reduction time TF50(t) is equal to or more than the monitoring time Tth0, the power reduction determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S504. When the power non-reduction time TF50(t) is smaller than the monitoring time Tth0, the power reduction determining section 50c-<NUM> determines No, and proceeds to the processing of step S505. The power non-reduction time TF50(t) corresponds to an operation time from a time of a start of operation of the control lever <NUM> or <NUM>, as described above. Incidentally, instead of using the power non-reduction time TF50(t) as the operation time, the operation time of the levers <NUM> and <NUM> may be calculated by directly using the sensor values P17b(t), P17r(t), P27b(t), P27r(t), P37b(t), P37r(t), P47l(t), and P47r(t) (operation pressures) of the pressure sensors 17b to 47r, and the operation time may be used.

In step S504, the power reduction determining section 50c-<NUM> determines whether a smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is equal to or more than the first set time Tth1 as a normal power reduction control time. When the smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is equal to or more than the first set time Tth1, the power reduction determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S506. When the smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is smaller than the first set time Tth1, the power reduction determining section 50c-<NUM> determines No, and proceeds to the processing of step S507.

In step S505, the power reduction determining section 50c-<NUM> determines whether the smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is equal to or more than the second set time Tth2. When the smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is equal to or more than the second set time Tth2, the power reduction determining section 50c-<NUM> determines Yes, and proceeds to the processing of step S508. When the smaller value of the lever <NUM> non-operation time Tu14(t) and the lever <NUM> non-operation time Tu34(t) is smaller than the second set time Tth2, the power reduction determining section 50c-<NUM> determines No, and proceeds to the processing of step S509.

Incidentally, the second set time Tth2 is set shorter than the first set time Tth1 as a normal power reduction control time. The first set time Tth1 is for example <NUM> to <NUM> seconds. The second set time Tth2 is for example <NUM> to <NUM> seconds.

In addition, the monitoring time Tth0 is set at a maximum value of a time for which an erroneous operation of the lever <NUM> or <NUM> can be considered to be performed. It is thereby possible to monitor the operation time (power non-reduction time TF50(t)) of the lever <NUM> or <NUM> during the monitoring time Tth0, and determine that an erroneous operation is performed when the operation time is shorter than the monitoring time Tth0.

The maximum value of the operation time for which an erroneous operation of the lever <NUM> or <NUM> can be considered to be performed can be determined by collecting data on the operation time in advance. In a case where the first set time Tth1 is for example <NUM> to <NUM> seconds, and the second set time Tth2 is for example <NUM> to <NUM> seconds, the monitoring time Tth0 is for example <NUM> to <NUM> seconds.

The power reduction determining section 50c-<NUM> performs same processing in step S506 and step S508. Specifically, in step S506 and step S508, the power reduction determining section 50c-<NUM> sets the power reduction flag true, and at the same time, the power reduction determining section 50c-<NUM> sets the target rotation speed for controlling the engine <NUM> to a targetrotation speed for power reduction control, which is lower than a normal target rotation speed indicated by the target rotation speed indicating device <NUM>. Then, the power reduction determining section 50c-<NUM> transmits the target rotation speed to the rotation speed controller <NUM>. The rotation speed controller <NUM> decreases the rotation speed of the engine <NUM> by reducing an amount of fuel supplied to the engine <NUM>. The power reduction determining section 50c-<NUM> thus performs power reduction control in step S506 and step S508.

The power reduction determining section 50c-<NUM> performs same processing in step S507 and step S509. Specifically, in step S507 and step S509, the power reduction determining section 50c-<NUM> sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50c-<NUM> sets the target rotation speed for controlling the engine <NUM> to the normal target rotation speed indicated by the target rotation speed indicating device <NUM>. Then, the power reduction determining section 50c-<NUM> transmits the target rotation speed to the rotation speed controller <NUM>. The rotation speed controller <NUM> increases the rotation speed of the engine <NUM> by increasing the amount of fuel supplied to the engine <NUM>. The power reduction determining section 50c-<NUM> thus cancels the power reduction control in step S507 and step S509.

An example of changes in operation pressures and target rotation speed in the first embodiment will next be described with reference to <FIG> is a timing diagram showing an example of changes in operation pressures and target rotation speed when the levers <NUM> and <NUM> are operated. An upper graph in <FIG> indicates temporal changes in the operation pressure P17b(t) by the lever <NUM>. A central graph indicates temporal changes in the operation pressure P37b(t) by the lever <NUM>. A lower graph indicates temporal changes in target rotation speed. An axis of abscissas in all of the graphs indicates time (seconds). In addition, the operation pressure threshold value Pth is also provided in the upper graph and the central graph.

At time t0, the lever <NUM> is operated in the forward direction 14b, and the lever <NUM> is operated in the right direction 34b. Therefore, both the operation pressure P17b(t) and the operation pressure P37b(t) exceed the threshold value Pth. The other operation pressures not shown in the figure are zero. At this time, the processing of step S507 in <FIG> is performed (S502 → S503 → S504 → S507), and the target rotation speed for controlling the engine <NUM> is thereby set to a normal value Nh indicated by the target rotation speed indicating device <NUM>. That is, the power reduction control (auto idle control) is canceled.

From time t0 to time t1, the operation pressures P17b(t) and P37b(t) are both larger than the threshold value Pth. Also in this case, the processing of step S507 in <FIG> is performed (S502 → S503 → S504 → S507), and the target rotation speed is thereby set to the normal value Nh.

At time t1, both of the levers <NUM> and <NUM> are returned to neutral, and thus both of the operation pressures P17b(t) and P37b(t) are a value smaller than the threshold value Pth. Therefore, until the first set time Tth1 passes from time t1, the processing of step S507 is performed (S502 → S503 → S504 → S507), and the target rotation speed for controlling the engine <NUM> is thereby set to the normal value Nh so that normal power control is performed. When the first set time Tth1 thereafter passes from time t1, the processing of step S506 in <FIG> is performed (S502 → S503 → S504 → S506) at time t1a, and the target rotation speed for controlling the engine <NUM> is thereby set to a value Nl smaller than the normal value Nh in the power reduction control (auto idle control) so that a transition is made to the power reduction control. Thereafter, the power reduction control is performed, and the power non-reduction time TF50(t) becomes zero. Thus, the processing of step S508 in <FIG> is performed, and the power reduction control is thereby continued (S502 → S503 → S505 → S508).

At time t2, the operation pressure P37b(t) is larger than the threshold value Pth due to an erroneous operation of the lever <NUM>. At this time, the processing of step S509 in <FIG> is performed (S502 → S503 → S505 → S509), and the target rotation speed for controlling the engine <NUM> thereby returns to the normal value Nh so that the power reduction control is canceled.

Thereafter, at time t3, the lever <NUM> returns to neutral, and the operation pressure P37b(t) is thereby decreased, thus both of the operation pressures P17b(t) and P37b(t) become a value smaller than the threshold value Pth (non-operation state). Therefore, until the second set time Tth2 passes from time t3, the processing of step S509 is performed (S502 → S503 → S505 → S509), and the target rotation speed for controlling the engine <NUM> thereby continues to be set to the normal value Nh so that the normal power control is performed. When the seconds of the second set time Tth2 thereafter pass from time t3, the processing of step S508 in <FIG> is performed (S502 → S503 → S505 → S508) at time t3a. The target rotation speed for controlling the engine <NUM> is thereby set to the value Nl smaller than the normal value Nh in the power reduction control (auto idle control) so that a transition is made to the power reduction control.

Incidentally, a time from time t2 to time t3 is an erroneous operation time of the lever <NUM>. Since the erroneous operation monitoring time Tth0 is set to the maximum value of the time for which an erroneous operation can be considered to be performed, it is possible to reliably monitor the erroneous operation time in step <NUM>, proceed to step S508 in the second set time. Tth2 shorter than the first set time Tth1, and perform the power reduction control.

Thereafter, at time t4, the operation pressure P37b(t) becomes larger than the threshold value Pth again due to an erroneous operation of the lever <NUM>. Also in this case, the processing of step S509 in <FIG> is performed (S502 → S503 → S505 → S509) so that the power reduction control is canceled.

Thereafter, at time t5, the lever <NUM> returns to neutral, and the operation pressure P37b(t) is thereby decreased, thus both of the operation pressures P17b(t) and P37b(t) become a value smaller than the threshold value Pth (non-operation state). Therefore, also in this case, until the second set time Tth2 passes from time t5, the processing of step S509 is performed (S502 → S503 → S505 → S509), and the target rotation speed for controlling the engine <NUM> thereby continues to be set to the normal value Nh so that the normal power control is performed. When the second set time Tth2 thereafter passes from time t5, the processing of step S508 in <FIG> is performed (S502 → S503 → S505 → S508) at time t5a, and the target rotation speed for controlling the engine <NUM> is thereby set to the value N1 smaller than the normal value Nh in the power reduction control (auto idle control) so that a transition is made to the power reduction control.

Incidentally, an erroneous operation time t4 to t5 in this case is longer than the erroneous operation time t2 to t3. However, the erroneous operation monitoring time Tth0 is set to the maximum value of the time for which an erroneous operation can be considered to be performed. Thus, the determination in step S503 continues to be negative during the erroneous operation. It is therefore possible to reliably monitor an erroneous operation in step <NUM>, proceed to step S508 in the second set time Tth2 shorter than the first set time Tth1 also in this case, and perform the power reduction control.

Thereafter, at time t6, the lever <NUM> is operated by the operator intending to perform work. At time t7, the lever <NUM> is returned to neutral.

At time t6, the operation pressure P17b(t) is larger than the threshold value Pth. At this time, the processing of step S509 in <FIG> is performed (S502 → S503 → S505 → S509), and the target rotation speed for controlling the engine <NUM> is thereby set to the normal value Nh so that the power reduction control is canceled.

An operation time from time t6 to time t7 is an operation time in which work is intended, and is longer than the erroneous operation monitoring time Tth0. Therefore, until the monitoring time Tth0 passes from time t6, the processing of step S509 is performed (S502 → S503 → S505 → S509), and the target rotation speed for controlling the engine <NUM> thereby continues to be set to the normal value Nh so that the normal power control is performed. When the seconds of the monitoring time Tth0 pass from time t6, the processing of step S507 is performed (S502 → S503 → S504 → S507) until time t7. Also in this case, the target rotation speed for controlling the engine <NUM> continues to be set to the normal value Nh so that the normal power control is performed.

When the lever <NUM> is thereafter returned to neutral at time t7, the operation pressure P17b(t) decreases, thus both of the operation pressures P17b(t) and P37b(t) become a value smaller than the threshold value Pth (non-operation state). Therefore, until the first set time Tth1 passes from time t7, the processing of step S507 is performed (S502 → S503 → S504 → S507), and the target rotation speed for controlling the engine <NUM> thereby continues to be set to the normal value Nh so that the normal power control is performed. When the first set time Tth1 thereafter passes from time t7, the processing of step S506 in <FIG> is performed (S502 → S503 → S504 → S506) at time t7a, and the target rotation speed for controlling the engine <NUM> is thereby set to the value N1 smaller than the normal value Nh in the power reduction control (auto idle control) so that a transition is made to the power reduction control. Thereafter, the power reduction control is performed, and the power non-reduction time TF50(t) becomes zero. Thus, the processing of step S508 in <FIG> is performed, and the power reduction control is continued (S502 → S503 → S505 → S508).

As described above, according to the present embodiment, the controller <NUM> performs the power reduction control that reduces the power output by the engine <NUM> and the hydraulic pump <NUM> (power source) when a transition is made from a state in which at least one of the control levers <NUM> and <NUM> (plurality of control levers) is operated to a non-operation state in which none of the control levers <NUM> and <NUM> is operated and a non-operation time after the transition to the non-operation state exceeds the set time Tth1 or Tth2. When at least one of the control levers <NUM> and <NUM> is operated in a state in which the power reduction control is performed, the controller <NUM> cancels the power reduction control, and restores the power output by the engine <NUM> and the hydraulic pump <NUM> to the power before the reduction.

It is thereby possible to perform the power reduction control during non-operation of the control levers, and make a smooth transition to an operation desired to be performed at a time of a return to a normal power state.

In addition, the controller <NUM> sets the set time as the first set time Tth1 when an operation time until at least one control lever makes a transition to the non-operation state is longer than the monitoring time Tth0 set in advance, and the controller <NUM> sets the set time as the second set time Tth2 shorter than the first set time Tth1 when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time Tth0 set in advance. Therefore, when the control lever(s) <NUM> and/or <NUM> is moved by an erroneous operation, the power reduction control is temporarily canceled, and a return is made to a normal power state. However, a return is thereafter made to a power reduction state in a short time.

It is thereby possible to suppress power consumption of the engine <NUM> (power source) and thus reduce an amount of fuel consumed by the engine <NUM> (energy consumption) when the control lever(s) <NUM> and/or <NUM> is moved by an erroneous operation.

In addition, the controller <NUM> generates the non-operation flags F14(t) and F34(t) (non-operation state information) and the power reduction flag F50(t) (power reduction control state information) on the basis of the operation states of the control levers <NUM> and <NUM>, which are detected by the pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r (plurality of operation state sensors), calculates the power non-reduction time TF50(t) on the basis of the non-operation flags F14(t) and F34(t) and the power reduction flag F50, and uses this power non-reduction time TF50(t) as the operation time of the control levers <NUM> and <NUM>. It is thereby possible to simplify the control computation of the controller <NUM>.

A second embodiment of the present invention will be described with reference to <FIG>. Incidentally, description of the present embodiment will be made centering on parts different from those of the first embodiment and a second modification, and description of parts similar to those of the first embodiment will be omitted.

A configuration of a driving system in the second embodiment will first be described. <FIG> is a diagram showing a configuration of a driving system in the present embodiment.

In <FIG>, the driving system in the second embodiment and the second modification is different from that in the first embodiment in that the hydraulic pump <NUM> is driven by a direct-current electric motor 60A. The electric motor 60A is electrically connected to a battery <NUM>, and is driven by electric power supplied from the battery <NUM>. The electric power output from the battery <NUM> is controlled by a battery output power control panel <NUM>. The battery output power control panel <NUM> is electrically connected to a controller 50A. The battery output power control panel <NUM> controls the electric power output by the battery <NUM> on the basis of target battery output power information transmitted from the controller 50A. The target rotation speed indicating device <NUM> is replaced with a target electric power indicating device 77A.

Here, the battery <NUM> constitutes an electric power supply device, and this electric power supply device, the electric motor 60A, and the hydraulic pump <NUM> constitute a power source. In addition, the power source drives the electric motor 60A by electric power supply from the electric power supply device (battery <NUM>), and generates power by driving the hydraulic pump <NUM> by the electric motor 60A.

Functions of the controller 50A in the second embodiment will next be described. <FIG> is a block diagram showing functions of the controller 50A.

The controller 50A performs power reduction control by reducing the electric power supplied to the electric motor 60A and thus reducing the rotation speed of the electric motor 60A.

Details of the above-described functions of the controller 50A will be described in the following. <FIG> is a block diagram showing functions of the controller 50A.

In <FIG>, the controller 50A in the second embodiment is different from that in the first embodiment in that the controller 50A includes a power computing section 50cA in place of the power computing section 50c, and the power computing section 50cA receives the pressure information and the switch flag transmitted from the sensor signal converting section 50a, the constant information and the table information transmitted from the constant and table storage section 50b, and a target voltage transmitted from the target voltage indicating device 77A, and computes a target current upper limit value as an output power target value of the battery <NUM>. The target current upper limit value computed by the power computing section 50cA is transmitted to the battery output power control panel <NUM>. The battery output power control panel <NUM> controls an upper limit value of output current of the battery <NUM> on the basis of the target current upper limit value.

Functions of the power computing section 50cA in the second embodiment will next be described. <FIG> is a block diagram showing functions of the power computing section 50cA.

In <FIG>, the power computing section 50cA in the second embodiment is different from that in the first embodiment in that the power computing section 50cA includes a power reduction determining section 50c-5A in place of the power reduction determining section 50c-<NUM>, and the power reduction determining section 50c-5A outputs the target current upper limit value. Inputs of the power reduction determining section 50c-5A are the same as those of the power reduction determining section 50c-<NUM> except that the target rotation speed indicating device <NUM> is replaced with the target electric power indicating device 77A.

A computation flow of the power reduction determining section 50c-5A in the second embodiment will next be described. <FIG> is a flowchart showing the computation flow of the power reduction determining section 50c-5A.

In <FIG>, the computation flow of the power reduction determining section 50c-5A in the second embodiment is different from the computation flow of the power reduction determining section 50c-<NUM> in the first embodiment, which is shown in <FIG>, in that the processing of step S510 is performed in place of step S506, the processing of step S511 is performed in place of step S507, the processing of step S512 is performed in place of step S508, and the processing of step S513 is performed in place of step S509.

In step S510, the power reduction determining section 50c-5A sets the power reduction flag F50(t) true, and at the same time, the power reduction determining section 50c-5A sets a target current upper limit value for control to a target current upper limit value for power reduction control, which is lower than a normal target current upper limit value. The normal target current upper limit value is a value obtained by dividing a target electric power indicated by the target electric power indicating device 77A by a rated voltage of the battery <NUM>. Then, the power reduction determining section 50c-5A transmits the target current upper limit value for power reduction control to the battery output power control panel <NUM>. The same processing as in step S510 is performed also in step S512.

In step S511, the power reduction determining section 50c-5A sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50c-5A sets the target current upper limit value for control to the normal target current upper limit value calculated from the target electric power indicated by the target electric power indicating device 77A. Then, the power reduction determining section 50c-5A transmits the normal target current upper limit value to the battery output power control panel <NUM>. The same processing as in step S511 is performed also in step S513.

The second embodiment configured as described above, in which the power source is constituted by the battery <NUM> (electric power supply device), the electric motor 60A, and the hydraulic pump <NUM>, provides effects similar to those of the first embodiment. Specifically, it is possible to perform power reduction control during non-operation of the control levers and make a smooth transition to an operation desired to be performed at a time of a return to a normal power state, and suppress electric power consumption of the electric motor 60A and thus reduce an amount of electric power consumed by the electric motor 60A (energy consumption) when the control lever(s) <NUM> and/or <NUM> is moved by an erroneous operation.

A third embodiment of the present invention will be described with reference to <FIG>. A power reduction in the present embodiment is performed by lowering the voltage of a driving system.

A configuration of a driving system in the third embodiment will first be described. <FIG> is a diagram showing a configuration of a driving system in the present embodiment.

In <FIG>, a controller 50B is electrically connected to an angle sensor <NUM>, an angle sensor <NUM>, an angle sensor <NUM>, and an angle sensor <NUM> shown in <FIG>, a switch <NUM>, and a target voltage indicating device 77B. The controller 50B receives signals of angle information, switch information, and target voltage information from these angle sensors <NUM> to <NUM>, the switch <NUM>, and the target voltage indicating device 77B. The controller 50B computes a target voltage for control as an output power target value for a battery <NUM> on the basis of these signals, and transmits the target voltage to a battery output power control panel <NUM> electrically connected to the controller 50B. The battery output power control panel <NUM> controls the voltage of the battery <NUM> so as to achieve the target voltage.

The battery <NUM> is connected to a positive electrode side wire <NUM> and a negative electrode side wire <NUM>. Inverters <NUM>, <NUM>, <NUM>, and <NUM> are connected in parallel to the positive electrode side wire <NUM> and the negative electrode side wire <NUM>.

The inverter <NUM> drives an electric motor <NUM>. The electric motor <NUM> further drives a cylinder <NUM> (boom cylinder). The cylinder <NUM> performs expansion and contraction by converting a rotary motion of the electric motor <NUM> into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter <NUM> receives a signal transmitted from the angle sensor <NUM>, and controls the electric motor <NUM> so as to achieve a rotation speed corresponding to the information of the signal.

The inverter <NUM> drives an electric motor <NUM>. The electric motor <NUM> further drives a cylinder <NUM> (arm cylinder). The cylinder <NUM> performs expansion and contraction by converting a rotary motion of the electric motor <NUM> into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter <NUM> receives a signal transmitted from the angle sensor <NUM>, and controls the electric motor <NUM> so as to achieve a rotation speed corresponding to the information of the signal.

The inverter <NUM> drives an electric motor <NUM>. The electric motor <NUM> further drives a cylinder <NUM> (bucket cylinder). The cylinder <NUM> performs expansion and contraction by converting a rotary motion of the electric motor <NUM> into a rectilinear motion by a rack-and-pinion mechanism or the like. The inverter <NUM> receives a signal transmitted from the angle sensor <NUM>, and controls the electric motor <NUM> so as to achieve a rotation speed corresponding to the information of the signal.

The inverter <NUM> drives an electric motor <NUM> (swing motor). The inverter <NUM> receives a signal transmitted from the angle sensor <NUM>, and controls the electric motor <NUM> so as to achieve a rotation speed corresponding to the information of the signal.

Here, the battery <NUM> is an electric power supply device, and this electric power supply device constitutes a power source. In addition, the electric motor <NUM> and the cylinder <NUM>, the electric motor <NUM> and the cylinder <NUM>, the electric motor <NUM> and the cylinder <NUM>, and the electric motor <NUM> are each an electric actuator, and constitute a plurality of actuators that are actuated by receiving power from the power source. The inverters <NUM>, <NUM>, <NUM>, and <NUM> constitute a power distributing device that distributes the power to the plurality of actuators (the electric motor <NUM> and the cylinder <NUM>, the electric motor <NUM> and the cylinder <NUM>, the electric motor <NUM> and the cylinder <NUM>, and the electric motor <NUM>).

Configurations of control lever devices in the third embodiment will next be described with reference to <FIG> and <FIG>.

<FIG> is a diagram showing configurations of control lever devices of the driving system in the third embodiment.

In <FIG>, the control lever devices in the third embodiment are different from the control lever devices in the first embodiment, which are shown in <FIG>, in that the control lever devices in the third embodiment include a control lever device <NUM> in place of the control lever device <NUM>, and include a control lever device <NUM> in place of the control lever device <NUM>. The control lever devices <NUM> and <NUM> are of an electric lever type. The control lever device <NUM> includes a lever <NUM>, an angle sensor <NUM> that detects angles in the forward direction 14b and the rearward direction 14r of the lever <NUM>, and an angle sensor <NUM> that detects angles in the left direction 24b and the right direction 24r of the lever <NUM>. The control lever device <NUM> includes a lever <NUM>, an angle sensor <NUM> that detects angles in the right direction 34b and the left direction 34r of the lever <NUM>, and an angle sensor <NUM> that detects angles in the forward direction <NUM> and the rearward direction 44r of the lever <NUM>.

The angle sensors <NUM>, <NUM>, <NUM>, and <NUM> constitute a plurality of operation state sensors that detect the operation states of the control lever devices <NUM> and <NUM>.

The angle sensors <NUM>, <NUM>, <NUM>, and <NUM> are electrically connected to the controller 50B, and transmit angle information to the controller 50B.

In addition, the angle sensor <NUM> is electrically connected to the inverter <NUM>, the angle sensor <NUM> is electrically connected to the inverter <NUM>, the angle sensor <NUM> is electrically connected to the inverter <NUM>, and the angle sensor <NUM> is electrically connected to the inverter <NUM>. The angle sensors <NUM>, <NUM>, <NUM>, and <NUM> transmit the angle information to the inverters <NUM>, <NUM>, <NUM>, and <NUM>, respectively.

<FIG> is a diagram showing relation between inclinations (angles) in the forward and rearward directions 14b and 14r of the lever <NUM> and the target rotation speed of the electric motor <NUM>. As shown in <FIG>, as the lever <NUM> is inclined in the forward direction 14b, the target rotation speed of the electric motor <NUM> is increased in a clockwise direction. In addition, the target rotation speed of the electric motor <NUM> is zero at a time of non-operation. As the lever <NUM> is inclined in the rearward direction 14r, the target rotation speed of the electric motor <NUM> is increased in a counterclockwise direction.

Also when the lever <NUM> is inclined in the right direction 24r or the left direction 24b, and the lever <NUM> is inclined in the right direction 34b or the left direction 34r and in the forward direction <NUM> or the rearward direction 44r, the target rotation speeds of the electric motors <NUM>, <NUM>, and <NUM> similarly change.

The control lever devices <NUM> and <NUM> instruct amounts of power to be distributed to the plurality of actuators (the electric motor <NUM> and the cylinder <NUM>, the electric motor <NUM> and the cylinder <NUM>, and the electric motor <NUM>) to the power distributing device (inverters <NUM>, <NUM>, <NUM>, and <NUM>) on the basis of the angle information detected by the angle sensors <NUM>, <NUM>, <NUM>, and <NUM> as described above.

Functions of the controller 50B in the third embodiment will next be described. <FIG> is a block diagram showing functions of the controller 50B.

In <FIG>, the controller 50B in the third embodiment is different from that in the second embodiment in that the controller 50B in the third embodiment includes a sensor signal converting section 50aB in place of the sensor signal converting section 50a, and includes a power computing section 50cB in place of the power computing section 50cA.

The sensor signal converting section 50aB receives signals sent from the angle sensors <NUM> to <NUM> and the switch <NUM>, and converts the signals into angle information and switch flag information. The sensor signal converting section 50aB transmits the converted angle information and the converted switch flag information to the power computing section 50cB.

The constant and table storage section 50b stores constants and tables necessary for calculation. The constant and table storage section 50b transmits the constants and the tables to the power computing section 50cB.

The power computing section 50cB receives the angle information and the switch flag information transmitted from the sensor signal converting section 50aB, the constant information and the table information transmitted from the constant and table storage section 50b, and the target voltage information transmitted from the target voltage indicating device 77B, and computes a target voltage for control of the battery <NUM>. Then, the power computing section 50cB outputs a command signal of the target voltage for control to the battery output power control panel <NUM>. The battery output power control panel <NUM> controls the voltage of the battery <NUM> on the basis of the value.

Sensor signal conversion processing in the sensor signal converting section 50aB will next be described. <FIG> is a diagram of assistance in explaining the conversion processing performed by the sensor signal converting section 50aB when the lever <NUM> is inclined in the forward direction 14b or the rearward direction 14r.

As shown in <FIG>, the sensor signal converting section 50aB performs conversion so that a sensor value A72(t) is increased as the lever <NUM> is inclined in the forward direction 14b. In addition, the sensor signal converting section 50aB performs conversion so that the sensor value A72(t) is zero at a time of non-operation. The sensor value A72(t) becomes a negative value when the lever <NUM> is inclined in the rearward direction 14r. The same is true when the lever <NUM> is inclined in the right direction 24r or the left direction 24b, and when the lever <NUM> is inclined in the right direction 34b or the left direction 34r and in the forward direction <NUM> or the rearward direction 44r. The sensor value A72(t) is a value corresponding to the target rotation speed of the electric motor <NUM> in <FIG>.

Functions of the power computing section 50cB in the third embodiment will next be described. <FIG> is a block diagram showing functions of the power computing section 50cB. Suppose that the sampling time of the controller 50B is Δt.

In <FIG>, the power computing section 50cB in the third embodiment is different from that in the second embodiment in that the power computing section 50cB in the third embodiment includes a lever <NUM> operation state determining section 50c-1B in place of the lever <NUM> operation state determining section 50c-<NUM>, includes a lever <NUM> operation state determining section 50c-2B in place of the lever <NUM> operation state determining section 50c-<NUM>, and includes a power reduction determining section 50c-5B in place of the power reduction determining section 50c-5A.

Functions of the lever <NUM> operation state determining section 50c-1B in the third embodiment will next be described. <FIG> is a flowchart showing a computation flow of the lever <NUM> operation state determining section 50c-1B. This computation flow is processed repeatedly in each sampling time Δt while the controller 50B operates, for example.

The computation flow of the lever <NUM> operation state determining section 50c-1B is different from the computation flow of the lever <NUM> operation state determining section 50c-<NUM> in the first embodiment, which is shown in <FIG>, in that the processing from step S102 to step S105 is eliminated, and the computation flow of the lever <NUM> operation state determining section 50c-1B proceeds from step S101 to the processing of step S110 and step S111.

In step S110, the lever <NUM> operation state determining section 50c-1B determines whether the absolute value of the sensor value A72(t) is smaller than a threshold value Ath. When the absolute value of the sensor value A72(t) is smaller than the threshold value Ath, the lever <NUM> operation state determining section 50c-1B determines Yes, and proceeds to the processing of step S111. When the absolute value of the sensor value A72(t) is equal to or larger than the threshold value Ath, the lever <NUM> operation state determining section 50c-1B determines No, and proceeds to the processing of step S107.

In step S111, the lever <NUM> operation state determining section 50c-1B determines whether the absolute value of a sensor value A73(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A73(t) is smaller than the threshold value Ath, the lever <NUM> operation state determining section 50c-1B determines Yes, and proceeds to the processing of step S106. When the absolute value of the sensor value A73(t) is equal to or larger than the threshold value Ath, the lever <NUM> operation state determining section 50c-1B determines No, and proceeds to the processing of step S107.

In step S106, the lever <NUM> operation state determining section 50c-1B sets the lever <NUM> non-operation flag F14(t) true. In step S107, the lever <NUM> operation state determining section 50c-1B sets the lever <NUM> non-operation flag F14(t) false. These pieces of flag information are transmitted to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power non-reduction time measuring section 50c-<NUM>.

Functions of the lever <NUM> operation state determining section 50c-2B in the third embodiment will next be described. <FIG> is a flowchart showing a computation flow of the lever <NUM> operation state determining section 50c-2B. This computation flow is processed repeatedly in each sampling time Δt while the controller 50B operates, for example.

The computation flow of the lever <NUM> operation state determining section 50c-2B is different from the computation flow of the lever <NUM> operation state determining section 50c-<NUM> in the first embodiment, which is shown in <FIG>, in that the processing from step S202 to step S205 is eliminated, and the computation flow of the lever <NUM> operation state determining section 50c-2B proceeds from step S201 to the processing of step S210 and step S211.

In step S210, the lever <NUM> operation state determining section 50c-2B determines whether the absolute value of a sensor value A74(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A74(t) is smaller than the threshold value Ath, the lever <NUM> operation state determining section 50c-2B determines Yes, and proceeds to the processing of step S211. When the absolute value of the sensor value A74(t) is equal to or larger than the threshold value Ath, the lever <NUM> operation state determining section 50c-2B determines No, and proceeds to the processing of step S207.

In step S211, the lever <NUM> operation state determining section 50c-2B determines whether the absolute value of a sensor value A75(t) is smaller than the threshold value Ath. When the absolute value of the sensor value A75(t) is smaller than the threshold value Ath, the lever <NUM> operation state determining section 50c-2B determines Yes, and proceeds to the processing of step S206. When the absolute value of the sensor value A75(t) is equal to or larger than the threshold value Ath, the lever <NUM> operation state determining section 50c-2B determines No, and proceeds to the processing of step S207.

In step S206, the lever <NUM> operation state determining section 50c-2B sets the lever <NUM> non-operation flag F34(t) true. In step S207, the lever <NUM> operation state determining section 50c-2B sets the lever <NUM> non-operation flag F34(t) false. These pieces of flag information are transmitted to the lever <NUM> non-operation time measuring section 50c-<NUM> and the power non-reduction time measuring section 50c-<NUM>.

Thus, the lever <NUM> operation state determining section 50c-1B determines whether the lever <NUM> is operated from the sensor value A72(t) and the sensor value A73(t), and outputs the lever <NUM> non-operation flag F14(t). The lever <NUM> operation state determining section 50c-2B determines whether the lever <NUM> is operated from the sensor value A74(t) and the sensor value A75(t), and outputs the lever <NUM> non-operation flag F34(t).

The lever <NUM> non-operation time measuring section 50c-<NUM> measures a lever <NUM> non-operation time Tu14(t) and the time information is transmitted to the power reduction determining section 50c-5B. The lever <NUM> non-operation time measuring section 50c-<NUM> measures a lever <NUM> non-operation time Tu34(t) and the time information is transmitted to the power reduction determining section 50c-5B.

A computation flow of the power reduction determining section 50c-5B in the third embodiment will next be described. <FIG> is a flowchart showing the computation flow of the power reduction determining section 50c-5B.

In <FIG>, the computation flow of the power reduction determining section 50c-5B in the third embodiment is different from the computation flow of the power reduction determining section 50c-5A in the second embodiment, which is shown in <FIG>, in that the processing of step S520 is performed in place of step S510, the processing of step S521 is performed in place of step S511, the processing of step S522 is performed in place of step S512, and the processing of step S523 is performed in place of step S513.

In step S520, the power reduction determining section 50c-5B sets the power reduction flag F50(t) true, and at the same time, the power reduction determining section 50c-5B sets the target voltage for control to a target voltage for power reduction control, which is lower than a normal target voltage. The target voltage is a target voltage indicated by the target voltage indicating device 77B. Then, the power reduction determining section 50c-5B transmits the target voltage for power reduction control to the battery output power control panel <NUM>. The same processing as in step S520 is performed also in step S522.

In step S521, the power reduction determining section 50c-5B sets the power reduction flag F50(t) false, and at the same time, the power reduction determining section 50c-5B sets the target voltage for control to the normal target voltage indicated by the target voltage indicating device 77B. Then, the power reduction determining section 50c-5B transmits the normal target voltage to the battery output power control panel <NUM>. The same processing as in step S521 is performed also in step S523.

The third embodiment configured as described above, in which the power source is constituted by the battery <NUM> (electric power supply device) and the actuators are constituted by electric actuators including the electric motors <NUM> to <NUM>, provides effects similar to those of the first embodiment. Specifically, it is possible to perform power reduction control during non-operation of the control levers and make a smooth transition to an operation desired to be performed at a time of a return to a normal power state, and reduce electric power consumption of the battery <NUM> and thus reduce an amount of electric power consumed by the battery <NUM> (energy consumption) when the control lever(s) <NUM> and/or <NUM> is moved by an erroneous operation.

In the first embodiment, description has been made of a case where the control lever devices <NUM> and <NUM> are of a hydraulic pilot type including pilot valves, and the operation state sensors are the pressure sensors 17b, 17r, 27b, 27r, 37b, 37r, <NUM>, and 47r that detect the operation pressures generated by the pilot valves. However, the operation states sensors may be of other configurations.

For example, the operation states of the control lever devices may be detected by providing one or a plurality of signal pressure generating lines that introduce the delivery oil of the pilot pump <NUM> shown in <FIG> to the tank <NUM>, arranging a plurality of signal pressure generating valves on the one or plurality of signal pressure generating lines, switching the signal pressure generating valves by the operation pressures generated by the pilot valves, and detecting the pressure of the signal pressure generating line(s), which is changed by opening or closing the signal pressure generating valves.

<FIG> is a diagram showing an example of an operation state sensor provided with such signal pressure generating valves.

In <FIG>, reference numeral 52a denotes a pilot line branched from the pilot line <NUM> (see <FIG> and <FIG>) connected to the pilot pump <NUM>. A signal pressure generating line 52b is connected to the pilot line 52a via a restricting section <NUM> and a check valve <NUM>. The downstream of the signal pressure generating line 52b is connected to the tank <NUM>. Normally open signal pressure generating valves 78a, 78b, 78c, and 78d are connected in series with each other on the signal pressure generating line 52b. A pressure sensor <NUM> is connected upstream of the signal pressure generating valves 78a, 78b, 78c, and 78d of the signal pressure generating line 52b.

The signal pressure generating valve 78a can be switched by operation pressure generated in the lines 16b and 16r shown in <FIG> and introduced to lines 16b-<NUM> and 16r-<NUM>. When the lever <NUM> is operated and thereby an operation pressure is generated in one of the lines 16b and 16r, the signal pressure generating valve 78a is closed, and a signal pressure is generated in the signal pressure generating line 52b. The pressure sensor <NUM> measures the pressure, and transmits a signal to the controller <NUM>.

The same is true for the signal pressure generating valves 78b, 78c, and 78d. When the lever <NUM> shown in <FIG> is operated, and thereby an operation pressure is generated in one of the lines 26b and 26r, the lines 36b and 36r, and the lines 46b and 46r, the signal pressure generating valve 78b, 78c, or 78d is closed, and a signal pressure is generated in the signal pressure generating line 52b. The pressure sensor <NUM> measures the pressure, and transmits a signal to the controller <NUM>.

The controller <NUM> determines whether at least one of the lever <NUM> and the lever <NUM> is operated on the basis of the signals transmitted from the pressure sensor <NUM>.

<FIG> is a diagram showing another example of an operation state sensor provided with signal pressure generating valves.

In <FIG>, normally closed signal pressure generating valves 79a, 79b, 79c, and 79d are connected in parallel to the signal pressure generating line 52b. downstream of the check valve <NUM>, and the downstreams of the signal pressure generating valves 79a, 79b, 79c, and 79d are each connected to the tank <NUM>.

When the lever <NUM> is operated and thereby an operation pressure is generated in one of the lines 16b and 16r, and the operation pressure is introduced to one of the lines 16b-<NUM> and 16r-<NUM>, the signal pressure generating valve 79a is opened, and the signal pressure generating line 52b is set to a tank pressure. The pressure sensor <NUM> measures the pressure as a signal pressure, and transmits a signal to the controller <NUM>.

The same is true for the signal pressure generating valves 79b, 79c, and 79d. When the lever <NUM> is operated and thereby an operation pressure is generated in one of the lines 26b and 26r, the lines 36b and 36r, and the lines 46b and 46r, the signal pressure generating valve 79b, 79c, or 79d is opened, and the signal pressure generating line 52b is set at the tank pressure. The pressure sensor <NUM> measures the pressure as a signal pressure, and transmits a signal to the controller <NUM>.

The controller, <NUM> determines whether at least one of the lever <NUM> and the lever <NUM> is operated on the basis of the signals transmitted from the pressure sensor <NUM>.

When the operation state sensor is configured as described above, one pressure sensor <NUM> suffices, and the configuration of the operation state sensor and the signal processing of the controller <NUM> can be simplified.

In addition, as another modification of the operation state sensor, even in a case where the control lever devices <NUM> and <NUM> are of a hydraulic pilot type as shown in <FIG>, the operation states of the control lever devices <NUM> and <NUM> may be detected by providing the angle sensors <NUM>, <NUM>, <NUM>, and <NUM> to the control levers <NUM> and <NUM> as in the third embodiment shown in <FIG>, and detecting the angles of the control levers <NUM> and <NUM>.

In the first embodiment, the power source of the driving system has a configuration including the engine <NUM>. In the second embodiment, the power source of the driving system has a configuration including the direct-current electric motor 60A. However, a configuration including an alternating-current electric motor may be adopted in place of the engine <NUM> or the direct-current electric motor 60A. <FIG> is a diagram showing a modification of such a driving system.

A driving system according to the present modification in <FIG> is different from that of the first embodiment in that the hydraulic pump <NUM> is driven by an alternating-current electric motor 60B, the hydraulic pump <NUM>, the alternating-current electric motor 60B, and the battery <NUM> constitute a power source of the driving system, and the electric motor 60B is controlled by an inverter <NUM>. The inverter <NUM> is electrically connected to the controller <NUM>.

The controller <NUM> calculates a target rotation speed for control by performing processing similar to that of the controller <NUM> shown in <FIG>. In addition, the inverter <NUM> is also electrically connected to the battery <NUM>. The inverter <NUM> converts the direct current of the battery <NUM> into a three-phase alternating current on the basis of the target rotation speed from the controller <NUM>. The electric motor 60B is driven by the alternating current.

Claim 1:
A construction machine comprising:
a power source (<NUM>, <NUM>);
a plurality of actuators (<NUM>, <NUM>, <NUM>, <NUM>) that operate by receiving a power from the power source (<NUM>, <NUM>);
a plurality of control levers (<NUM>, <NUM>) that instruct amounts of the power to be distributed to the plurality of actuators (<NUM>, <NUM>, <NUM>, <NUM>);
a plurality of operation state sensors (17r, 17b, <NUM>, 27b, 37r, 37b, 47r, <NUM>) that detect operation states of the plurality of control levers (<NUM>, <NUM>); and
a controller (<NUM>) that controls the power output by the power source (<NUM>, <NUM>),
the controller (<NUM>) being configured to perform power reduction control of the power source (<NUM>, <NUM>) on a basis of the operation states of the plurality of control levers (<NUM>, <NUM>) detected by the plurality of operation state sensors (17r, 17b, <NUM>, 27b, 37r, 37b, 47r, <NUM>) when a non-operation time of the plurality of control levers (<NUM>, <NUM>) exceeds a set time after a transition is made from a state in which at least one of the plurality of control levers (<NUM>, <NUM>) is operated to a non-operation state in which none of the plurality of control levers (<NUM>, <NUM>) is operated, and to cancel the power reduction control when at least one of the plurality of control levers (<NUM>, <NUM>) is operated in a state in which the power reduction control is performed,
characterised in that
the controller (<NUM>) is further configured to set the set time as a first set time (Tth1) when an operation time until the at least one control lever makes a transition to the non-operation state is longer than a monitoring time (Tth0) set in advance, and
set the set time as a second set time (Tth2) shorter than the first set time (Tth1) when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time (Tth0) set in advance.